U.S. patent application number 16/946622 was filed with the patent office on 2021-03-11 for thermoplastic polymer particles and methods of production and uses thereof.
This patent application is currently assigned to Xerox Corporation. The applicant listed for this patent is Xerox Corporation. Invention is credited to Robert Claridge, Valerie M. Farrugia, Michael S. Hawkins, Carolyn Patricia Moorlag, Cristina Resetco, Shivanthi Easwari Sriskandha.
Application Number | 20210070993 16/946622 |
Document ID | / |
Family ID | 1000005133966 |
Filed Date | 2021-03-11 |
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United States Patent
Application |
20210070993 |
Kind Code |
A1 |
Farrugia; Valerie M. ; et
al. |
March 11, 2021 |
Thermoplastic Polymer Particles and Methods of Production and Uses
Thereof
Abstract
Thermoplastic polymer particles can be produced that comprise a
thermoplastic polymer and an emulsion stabilizer (e.g.,
nanoparticles and/or surfactant) associated with an outer surface
of the particles. The nanoparticles may be embedded in the outer
surface of the particles. Melt emulsification can be used to
produce said particles. For example, a method may include: mixing a
mixture comprising a thermoplastic polymer, an carrier fluid that
is immiscible with the thermoplastic polymer, and the emulsion
stabilizer at a temperature greater than a melting point or
softening temperature of the thermoplastic polymer and at a shear
rate sufficiently high to disperse the thermoplastic polymer in the
carrier fluid; cooling the mixture to below the melting point or
softening temperature of the thermoplastic polymer to form the
thermoplastic polymer particles; and separating the thermoplastic
polymer particles from the carrier fluid.
Inventors: |
Farrugia; Valerie M.;
(Oakville, CA) ; Resetco; Cristina; (Toronto,
CA) ; Hawkins; Michael S.; (Cambridge, CA) ;
Sriskandha; Shivanthi Easwari; (Mississauga, CA) ;
Claridge; Robert; (Kitchener, CA) ; Moorlag; Carolyn
Patricia; (Mississauga, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Xerox Corporation |
Norwalk |
CT |
US |
|
|
Assignee: |
Xerox Corporation
Norwalk
CT
|
Family ID: |
1000005133966 |
Appl. No.: |
16/946622 |
Filed: |
June 30, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62897534 |
Sep 9, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 2205/14 20130101;
C08L 83/04 20130101; C08L 75/08 20130101; C08L 77/06 20130101; C08L
67/03 20130101; C08L 23/12 20130101; C08L 2207/02 20130101; C08L
2207/04 20130101 |
International
Class: |
C08L 77/06 20060101
C08L077/06; C08L 83/04 20060101 C08L083/04; C08L 75/08 20060101
C08L075/08; C08L 67/03 20060101 C08L067/03; C08L 23/12 20060101
C08L023/12 |
Claims
1. A composition comprising: particles comprising a thermoplastic
polymer and an emulsion stabilizer associated with an outer surface
of the particles, wherein the particles have a circularity of about
0.90 to about 1.0.
2. The composition of claim 1, wherein the emulsion stabilizer
comprises nanoparticles and at least some of the nanoparticles are
embedded in the outer surface of the particles.
3. The composition of claim 1, wherein at least some of the
particles have a void therein comprising the emulsion stabilizer at
a void/thermoplastic polymer interface.
4. The composition of claim 3, wherein the void contains a carrier
fluid having a viscosity at 25.degree. C. of 1,000 cSt to 150,000
cSt.
5. The composition of claim 4, wherein the carrier fluid is
selected from the group consisting of: silicone oil, fluorinated
silicone oils, perfluorinated silicone oils, polyethylene glycols,
alkyl-terminal polyethylene glycols, paraffins, liquid petroleum
jelly, vison oils, turtle oils, soya bean oils, perhydrosqualene,
sweet almond oils, calophyllum oils, palm oils, parleam oils,
grapeseed oils, sesame oils, maize oils, rapeseed oils, sunflower
oils, cottonseed oils, apricot oils, castor oils, avocado oils,
jojoba oils, olive oils, cereal germ oils, esters of lanolic acid,
esters of oleic acid, esters of lauric acid, esters of stearic
acid, fatty esters, higher fatty acids, fatty alcohols,
polysiloxanes modified with fatty acids, polysiloxanes modified
with fatty alcohols, polysiloxanes modified with polyoxy alkylenes,
and any combination thereof
6. The composition of claim 1 further comprising: elongated
structures on the surface of the particles, wherein the elongated
structures comprises the thermoplastic polymer with the emulsion
stabilizer associated with an outer surface of the elongated
structures.
7. The composition of claim 1, wherein the emulsion stabilizer
forms a coating that covers at least 25% of the surface of the
particles.
8. The composition of claim 1, wherein the thermoplastic polymer is
selected from the group consisting of: polyamides, polyurethanes,
polyethylenes, polypropylenes, polyacetals, polycarbonates,
polybutylene terephthalate (PBT), polyethylene terephthalate (PET),
polyethylene naphthalate (PEN), polytrimethylene terephthalate
(PTT), polyhexamethylene terephthalate, polystyrenes, polyvinyl
chlorides, polytetrafluoroethenes, polyesters (e.g., polylactic
acid), polyethers, polyether sulfones, polyetherether ketones,
polyacrylates, polymethacrylates, polyimides, acrylonitrile
butadiene styrene (ABS), polyphenylene sulfides, vinyl polymers,
polyarylene ethers, polyarylene sulfides, polysulfones, polyether
ketones, polyamide-imides, polyetherimides, polyetheresters,
copolymers comprising a polyether block and a polyamide block (PEBA
or polyether block amide), grafted or ungrafted thermoplastic
polyolefins, functionalized or nonfunctionalized ethylene/vinyl
monomer polymer, functionalized or nonfunctionalized ethylene/alkyl
(meth)acrylates, functionalized or nonfunctionalized (meth)acrylic
acid polymers, functionalized or nonfunctionalized ethylene/vinyl
monomer/alkyl (meth)acrylate terpolymers, ethylene/vinyl
monomer/carbonyl terpolymers, ethylene/alkyl
(meth)acrylate/carbonyl terpolymers,
methylmethacrylate-butadiene-styrene (MBS)-type core-shell
polymers, polystyrene-block-polybutadiene-block-poly(methyl
methacrylate) (SBM) block terpolymers, chlorinated or
chlorosulphonated polyethylenes, polyvinylidene fluoride (PVDF),
phenolic resins, poly(ethylene/vinyl acetate)s, polybutadienes,
polyisoprenes, styrenic block copolymers, polyacrylonitriles,
silicones, and any combination thereof.
9. The composition of claim 1, wherein the thermoplastic polymer is
a first thermoplastic polymer, and wherein the particles further
comprise a second thermoplastic polymer and a compatibilizer.
10. The composition of claim 1, wherein the particles have a D10 of
about 0.5 .mu.m to about 125 .mu.m, a D50 of about 1 .mu.m to about
200 .mu.m, and a D90 of about 70 .mu.m to about 300 .mu.m, wherein
D10<D50<D90.
11. The composition of claim 1, wherein the particles have a
diameter span of about 0.2 to about 10.
12. The composition of claim 1, wherein the particles have a
Hausner ratio of about 1.0 to about 1.5.
13. The composition of claim 1, wherein the nanoparticles comprise
particles selected from the group consisting of: oxide
nanoparticles, carbon black, polymer nanoparticles, and any
combination thereof.
14. A composition comprising: particles comprising a thermoplastic
polymer and an emulsion stabilizer embedded in an outer surface of
the particles, wherein the particles have a circularity of about
0.90 to about 1.0, wherein at least some of the particles have a
void therein comprising the emulsion stabilizer at a
void/thermoplastic polymer interface.
15. A method comprising: mixing a mixture comprising a
thermoplastic polymer, an carrier fluid that is immiscible with the
thermoplastic polymer, and an emulsion stabilizer at a temperature
greater than a melting point or softening temperature of the
thermoplastic polymer and at a shear rate sufficiently high to
disperse the thermoplastic polymer in the carrier fluid; cooling
the mixture to below the melting point or softening temperature of
the thermoplastic polymer to form solidified particles comprising
the thermoplastic polymer and the emulsion stabilizer associated
with an outer surface of the solidified particles; and separating
the solidified particles from the carrier fluid.
16. The method of claim 15, wherein the emulsion stabilizer
comprises nanoparticles at least some of the nanoparticles are
embedded in the outer surface of the solidified particles.
17. The method of claim 15, wherein the emulsion stabilizer
comprises nanoparticles selected from the group consisting of:
oxide nanoparticles, carbon black, polymer nanoparticles, and any
combination thereof.
18. The method of claim 15, wherein the solidified particles
further comprises elongated structures on the surface of the
solidified particles, wherein the elongated structures comprises
the thermoplastic polymer with the emulsion stabilizer associated
with an outer surface of the elongated structures.
19. The method of claim 15, wherein the emulsion stabilizer is
present in the mixture at 0.01 wt % to 10 wt % by weight of the
thermoplastic polymer.
20. The method of claim 15, wherein the thermoplastic polymer is
present the mixture at 5 wt % to 60 wt % of the mixture.
Description
PRIORITY CLAIM
[0001] The present application claims priority to U.S. Provisional
Patent Application No. 62/897,534.
TECHNICAL FIELD
[0002] The present disclosure relates to thermoplastic polymer
particles and methods of making such particles. Such particles,
especially the highly spherical thermoplastic polymer particles,
may be useful, among other things, as starting material for
additive manufacturing.
BACKGROUND
[0003] Three-dimensional (3-D) printing, also known as additive
manufacturing, is a rapidly growing technology area. Although 3-D
printing has traditionally been used for rapid prototyping
activities, this technique is being increasingly employed for
producing commercial and industrial objects, which may have
entirely different structural and mechanical tolerances than do
rapid prototypes.
[0004] 3-D printing operates by depositing either (a) small
droplets or streams of a melted or solidifiable material or (b)
powder particulates in precise deposition locations for subsequent
consolidation into a larger object, which may have any number of
complex shapes. Such deposition and consolidation processes
typically occur under the control of a computer to afford
layer-by-layer buildup of the larger object. In a particular
example, consolidation of powder particulates may take place in a
3-D printing system using a laser to promote selective laser
sintering (SLS). Incomplete interlayer fusion may result in
structural weak points, which may be problematic for printing
objects having exacting structural and mechanical tolerances.
[0005] Powder particulates usable in 3-D printing include
thermoplastic polymers, including thermoplastic elastomers, metals
and other solidifiable substances. Although a wide array of
thermoplastic polymers are known, there are relatively few having
properties suitable for use in 3-D printing, particularly when
using powder bed fusion (PBF). Additive manufacturing methods using
powdered materials include PBF, selective laser sintering (SLS),
selective heat sintering (SHM), selective laser melting (SLM),
electron beam melting (EBM), binder jetting, and multi jet fusion
(MJF). In the SLS printing method, the particles are fused together
by the energy from a high-powered laser. Typical thermoplastic
polymers suitable for use in 3-D printing include those having
sharp melting points and recrystallization points about 20.degree.
C. to 50.degree. C. below the melting point. This difference may
allow more effective coalescence between adjacent polymer layers to
take place, thereby promoting improved structural and mechanical
integrity.
[0006] For good printing performance to be realized using powder
particulates, particularly polymer powder particulates, the powder
particulates need to maintain good flow properties in the solid
state. Flow properties may be evaluated, for example, by measuring
the fraction of powder particulates from a sample that are able to
pass through a standard sieve of a specified size and/or measuring
of the angle of repose. High fractions of sievable powder
particulates may be indicative of the particulates existing as
non-agglomerated, substantially individual particulates, which may
be characteristic of ready powder flow. Lower values of the angle
of repose, in contrast, may be characteristic of ready powder flow.
A relatively narrow particle size distribution and regularity of
the particulate shape in a sample may also aid in promoting good
powder flow performance.
[0007] Commercial powder particulates are oftentimes obtained by
cryogenic grinding or precipitation processes, which may result in
irregular particulate shapes and wide particle size distributions.
Irregular particulate shapes may result in poor powder flow
performance during 3-D printing processes. In addition, powder
particulates having shape irregularity, especially those obtained
from current commercial processes, may afford poor packing
efficiency following deposition and consolidation, thereby
resulting in extensive void formation in a printed object due to
the powder particulates not packing closely together during
deposition. Wide particle size distributions may be similarly
problematic in this regard. Although poor powder flow performance
may be addressed to some degree through dry blending with fillers
and flow aids, these techniques may have limited effectiveness with
softer polymer materials, such as elastomers, due to particulate
aggregation.
SUMMARY OF THE INVENTION
[0008] The present disclosure relates to thermoplastic polymer
particles and methods of making such particles. Such particles,
especially the highly spherical thermoplastic polymer particles,
may be useful, among other things, as starting material for
additive manufacturing.
[0009] Described herein is a composition comprising: particles
comprising a thermoplastic polymer and an emulsion stabilizer
(e.g., nanoparticles and/or surfactant) associated with an outer
surface of the particles.
[0010] Described herein is a method comprising: mixing a mixture
comprising a thermoplastic polymer, an carrier fluid that is
immiscible with the thermoplastic polymer, and emulsion stabilizer
(e.g., nanoparticles and/or surfactant) at a temperature greater
than a melting point or softening temperature of the thermoplastic
polymer and at a shear rate sufficiently high to disperse the
thermoplastic polymer in the carrier fluid; cooling the mixture to
below the melting point or softening temperature of the
thermoplastic polymer to form solidified particles comprising the
thermoplastic polymer and the emulsion stabilizer associated with
an outer surface of the solidified particles; and separating the
solidified particles from the carrier fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The following figures are included to illustrate certain
aspects of the embodiments, and should not be viewed as exclusive
embodiments. The subject matter disclosed is capable of
considerable modifications, alterations, combinations, and
equivalents in form and function, as will occur to those skilled in
the art and having the benefit of this disclosure.
[0012] FIG. 1 is a flow chart of a nonlimiting example method 100
of the present disclosure.
[0013] FIG. 2 is a scanning electron micrograph of polyamide
particles.
[0014] FIG. 3 is a scanning electron micrograph of polyamide
particles.
[0015] FIG. 4 is a scanning electron micrograph of polyamide
particles.
[0016] FIG. 5 is a scanning electron micrograph of polyamide
particles.
[0017] FIG. 6 is a scanning electron micrograph of polyamide
particles.
[0018] FIG. 7 is a scanning electron micrograph of polyamide
particles.
[0019] FIG. 8 is a scanning electron micrograph of polyamide
particles.
[0020] FIG. 9 is a scanning electron micrograph of polyamide
particles.
[0021] FIG. 10 is a scanning electron micrograph of polyamide
particles.
[0022] FIG. 11 is a scanning electron micrograph of polyamide
particles.
[0023] FIG. 12 is a scanning electron micrograph of polyamide
particles.
[0024] FIG. 13 is a scanning electron micrograph of polyamide
particles.
[0025] FIG. 14 is a scanning electron micrograph of polyamide
particles.
[0026] FIG. 15 is a scanning electron micrograph of polyamide
particles.
[0027] FIG. 16 is a scanning electron micrograph of polyamide
particles.
[0028] FIG. 17 is a scanning electron micrograph of polyamide
particles.
[0029] FIG. 18 is a scanning electron micrograph of polyamide
particles.
[0030] FIG. 19 is a scanning electron micrograph of polyamide
particles.
[0031] FIG. 20 is a scanning electron micrograph of polyamide
particles.
[0032] FIG. 21 is a scanning electron micrograph of polyamide
particles.
[0033] FIG. 22 is a scanning electron micrograph of polyamide
particles.
[0034] FIGS. 23A and 23B are scanning electron micrographs of
polyamide particles.
[0035] FIG. 24 is a scanning electron micrograph of polyamide
particles.
[0036] FIGS. 25 and 26 are the volume density particle size
distribution for the particles screened and not screened,
respectively.
[0037] FIG. 27 shows an illustrative optical microscopy image at
150.times. magnification of thermoplastic polyurethane
particulates.
[0038] FIG. 28 shows an illustrative optical microscopy image of
thermoplastic polyurethane particulates.
[0039] FIGS. 29A and 29B show illustrative SEM images of
thermoplastic polyurethane particulates obtained in Comparative
Example 2 at various magnifications.
[0040] FIG. 30 shows an illustrative optical microscopy image of
thermoplastic polyurethane particulates.
[0041] FIG. 31 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0042] FIG. 32 shows an illustrative optical microscopy image of
thermoplastic polyurethane particulates.
[0043] FIG. 33 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0044] FIG. 34 shows an illustrative optical microscopy image of
thermoplastic polyurethane particulates.
[0045] FIGS. 35A and 35B show illustrative SEM images of
thermoplastic polyurethane particulates at various
magnifications.
[0046] FIG. 36 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0047] FIG. 37 shows an illustrative optical microscopy image of
thermoplastic polyurethane particulates.
[0048] FIGS. 38A-38D show illustrative SEM images of thermoplastic
polyurethane particulates at various magnifications.
[0049] FIG. 39 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0050] FIG. 40 shows an illustrative optical microscopy image of
thermoplastic polyurethane particulates.
[0051] FIGS. 41A-41C show illustrative SEM images of thermoplastic
polyurethane particulates at various magnifications.
[0052] FIG. 42 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0053] FIGS. 43A-43E show illustrative SEM images of TPU 90A NAT
thermoplastic polyurethane particulates (ADVANC3D).
[0054] FIG. 44 shows an optical image of the printed product
obtained from the thermoplastic polyurethane particulates.
[0055] FIG. 45 shows an illustrative optical microscopy image at
150.times. magnification of thermoplastic polyurethane
particulates.
[0056] FIG. 46 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0057] FIG. 47 shows an illustrative optical microscopy image at
150.times. magnification of thermoplastic polyurethane
particulates.
[0058] FIGS. 48A and 48B show illustrative SEM images of
thermoplastic polyurethane particulates obtained in at various
magnifications.
[0059] FIG. 49 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0060] FIG. 50 shows an illustrative optical microscopy image at
100.times. magnification of thermoplastic polyurethane particulates
obtained in.
[0061] FIG. 51 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0062] FIG. 52 shows an illustrative optical microscopy image at
100.times. magnification of thermoplastic polyurethane
particulates.
[0063] FIG. 53 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0064] FIG. 54 shows an illustrative optical microscopy image at
300.times. magnification of thermoplastic polyurethane
particulates.
[0065] FIG. 55 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0066] FIG. 56 shows an illustrative optical microscopy image at
150.times. magnification of thermoplastic polyurethane
particulates.
[0067] FIG. 57 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0068] FIG. 58 shows an illustrative optical microscopy image at
150.times. magnification of thermoplastic polyurethane
particulates.
[0069] FIG. 59 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0070] FIG. 60 shows an illustrative optical microscopy image at
150.times. magnification of thermoplastic polyurethane
particulates.
[0071] FIGS. 61A and 61B show illustrative SEM images of
thermoplastic polyurethane particulates at various
magnifications.
[0072] FIG. 62 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0073] FIG. 63 shows an illustrative optical microscopy image at
150.times. magnification of thermoplastic polyurethane
particulates.
[0074] FIG. 64 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates.
[0075] FIG. 65 shows an illustrative particle size distribution
plot for thermoplastic polyurethane particulates.
[0076] FIG. 66 shows an optical image of the printed product.
DETAILED DESCRIPTION
[0077] The present disclosure relates to thermoplastic polymer
particles and methods of making such particles. Such particles,
especially the highly spherical thermoplastic polymer particles,
may be useful, among other things, as starting material for
additive manufacturing.
[0078] More specifically, the thermoplastic polymer particles
described herein are produced by melt emulsification methods where
a thermoplastic polymer is dispersed as a melt in a carrier fluid
that is immiscible with the thermoplastic polymer. A sufficient
amount of shear is used to cause the thermoplastic polymer melt to
form droplets in the carrier fluid. Emulsion stabilizers (e.g.,
nanoparticles and/or surfactants, including one or more members of
each type in some cases) effect the surface tension at the phase
interface between the carrier fluid and the thermoplastic polymer
melt. Once the melt emulsification process is complete, the
dispersion is cooled, which solidifies the polymer into
thermoplastic polymer particles.
[0079] Without being limited by theory, during the melt
emulsification process, the emulsion stabilizers primarily reside
at the interface between the polymer melt and the carrier fluid. As
a result, when the mixture is cooled, the emulsion stabilizers
remain at said interface. Advantageously, the emulsion stabilizers
at a surface of the resultant particles may assist with the flow
properties of the resultant particles.
[0080] As described previously, traditional methods of forming
thermoplastic polymer particles with good flowability include at
least two steps including first forming (e.g., by cryogenic
grinding or precipitation processes) and purifying the particles
and second coating the particles to some degree with a flow
enhancing agent like nanoparticle silica, carbon black, or PTFE
particles. The methods described herein advantageously produce
thermoplastic polymer particles with a coating that enhances
flowability of the particles in one process.
[0081] Further, without limitation by theory, the methods of the
present disclosure appear to produce particles with a more
homogeneous coverage of emulsion stabilizers, which may further
improve flowability. Enhanced flowability is especially
advantageous in additive manufacturing applications like 3-D
printing.
Definitions and Test Methods
[0082] As used herein, the term "immiscible" refers to a mixture of
components that, when combined, form two or more phases that have
less than 5 wt % solubility in each other at ambient pressure and
at room temperature or the melting point of the component if it is
solid at room temperature. For example, polyethylene oxide having
10,000 g/mol molecular weight is a solid at room temperature and
has a melting point of 65.degree. C. Therefore, said polyethylene
oxide is immiscible with a material that is liquid at room
temperature if said material and said polyethylene oxide have less
than 5 wt % solubility in each other at 65.degree. C.
[0083] As used herein, the term "thermoplastic polymer" refers to a
plastic polymer material that softens and hardens reversibly on
heating and cooling. Thermoplastic polymers encompass thermoplastic
elastomers.
[0084] As used herein, the term "elastomer" refers to a copolymer
comprising a crystalline "hard" section and an amorphous "soft"
section. In the case of a polyurethane, the crystalline section may
include a portion of the polyurethane comprising the urethane
functionality and optional chain extender group, and the soft
section may include the polyol, for instance.
[0085] As used herein, the term "polyurethane" refers to a
polymeric reaction product between a diisocyanate, a polyol, and an
optional chain extender.
[0086] As used herein, the term "oxide" refers to both metal oxides
and non-metal oxides. For purposes of the present disclosure,
silicon is considered to be a metal.
[0087] As used herein, the terms "associated," "association," and
grammatical variations thereof between emulsion stabilizers and a
surface refers to chemical bonding and/or physical adherence of the
emulsion stabilizers to the surface. Without being limited by
theory, it is believed that the associations described herein
between polymers and emulsion stabilizers are primarily physical
adherences via hydrogen bonding and/or other mechanisms. However,
chemical bonding may be occurring to some degree.
[0088] As used herein, the term "embed" relative to nanoparticles
and a surface of a polymer particle refers to the nanoparticle
being at least partially extending into the surface such that
polymer is in contact with the nanoparticle to a greater degree
than would be if the nanoparticle were simply laid on the surface
of the polymer particle.
[0089] Herein, D10, D50, D90, and diameter span are primarily used
herein to describe particle sizes. As used herein, the term "D10"
refers to a diameter at with 10% of the sample (on a volume basis
unless otherwise specified) is comprised of particles having a
diameter less than said diameter value. As used herein, the term
"D50" refers to a diameter at with 50% of the sample (on a volume
basis unless otherwise specified) is comprised of particles having
a diameter less than said diameter value. As used herein, the term
"D90" refers to a diameter at with 90% of the sample (on a volume
basis unless otherwise specified) is comprised of particles having
a diameter less than said diameter value.
[0090] As used herein, the terms "diameter span" and "span" and
"span size" when referring to diameter provides an indication of
the breadth of the particle size distribution and is calculated as
(D90-D10)/D50 (again each D-value is based on volume, unless
otherwise specified).
[0091] Particle size can be determined by light scattering
techniques using a Malvern MASTERSIZER.TM. 3000 or analysis of
optical digital micrographs. Unless otherwise specified, light
scattering techniques are used for analyzing particle size.
[0092] For light scattering techniques, the control samples were
glass beads with a diameter within the range of 15 .mu.m to 150
.mu.m under the tradename Quality Audit Standards QAS4002.TM.
obtained from Malvern Analytical Ltd. Samples were analyzed as dry
powders, unless otherwise indicated. The particles analyzed were
dispersed in air and analyzed using the AERO S dry powder
dispersion module with the MASTERSIZER.TM. 3000. The particle sizes
were derived using instruments software from a plot of volume
density as a function of size.
[0093] Particle size measurement and diameter span can also be
determined by optical digital microscopy. The optical images are
obtained using a Keyence VHX-2000 digital microscope using version
2.3.5.1 software for particle size analysis (system version
1.93).
[0094] As used herein, when referring to sieving, pore/screen sizes
are described per U.S.A. Standard Sieve (ASTM E11-17).
[0095] As used herein, the terms "circularity" and "sphericity"
relative to the particles refer to how close the particle is to a
perfect sphere. To determine circularity, optical microscopy images
are taken of the particles. The perimeter (P) and area (A) of the
particle in the plane of the microscopy image is calculated (e.g.,
using a SYSMEX FPIA 3000 particle shape and particle size analyzer,
available from Malvern Instruments). The circularity of the
particle is C.sub.EA/P, where C.sub.EA is the circumference of a
circle having the area equivalent to the area (A) of the actual
particle.
[0096] As used herein, the term "sintering window" refers to the
difference between the melting temperature (Tm) onset and the
crystallization temperature (Tc) onset, or (Tm-Tc) onset. Tm, Tm
(onset), Tc, and Tc (onset) are determined by differential scanning
calorimetry per ASTM E794-06(2018) with a 10.degree. C./min ramp
rate and a 10.degree. C./min cool rate.
[0097] As used herein, the term "shear" refers to stirring or a
similar process that induces mechanical agitation in a fluid.
[0098] As used herein, the term "aspect ratio" refers to length
divided by width, wherein the length is greater than the width.
[0099] The melting point of a polymer, unless otherwise specified,
is determined by ASTM E794-06(2018) with 10.degree. C./min ramping
and cooling rates.
[0100] The softening temperature or softening point of a polymer,
unless otherwise specified, is determined by ASTM D6090-17. The
softening temperature can be measured by using a cup and ball
apparatus available from Mettler-Toledo using a 0.50 gram sample
with a heating rate of 1.degree. C./min.
[0101] Angle of repose is a measure of the flowability of a powder.
Angle of repose measurements were determined using a Hosokawa
Micron Powder Characteristics Tester PT-R using ASTM D6393-14
"Standard Test Method for Bulk Solids" Characterized by Carr
Indices."
[0102] Hausner ratio (H.sub.r) is a measure of the flowability of a
powder and is calculated by H.sub.r=.rho..sub.tap/.rho..sub.bulk,
where .rho..sub.bulk is the bulk density per ASTM D6393-14 and
.rho..sub.tap is the tapped density per ASTM D6393-14.
[0103] As used herein, the term "embed" relative to nanoparticles
and a surface of a polymer particle refers to the nanoparticle
being at least partially extending into the surface such that
polymer is in contact with the nanoparticle to a greater degree
than would be if the nanoparticle were simply laid on the surface
of the polymer particle.
[0104] As used herein, viscosity of carrier fluids are the
kinematic viscosity at 25.degree. C., unless otherwise specified,
measured per ASTM D445-19. For commercially procured carrier fluids
(e.g., PDMS oil), the kinematic viscosity data cited herein was
provided by the manufacturer, whether measured according to the
foregoing ASTM or another standard measurement technique.
Thermoplastic Polymer Particles and Methods of Making
[0105] FIG. 1 is a flow chart of a nonlimiting example method 100
of the present disclosure. The thermoplastic polymer 102, carrier
fluid 104, and emulsion stabilizer 106 are combined 108 to produce
a mixture 110. The components 102, 104, and 106 can be added in any
order and include mixing and/or heating during the process of
combining 108 the components 102, 104, and 106.
[0106] The mixture 110 is then processed 112 by applying
sufficiently high shear to the mixture 110 at a temperature greater
than the melting point or softening temperature of the
thermoplastic polymer 102 to form a melt emulsion 114. Because the
temperature is above the melting point or softening temperature of
the thermoplastic polymer 102, the thermoplastic polymer 102
becomes a polymer melt. The shear rate should be sufficient enough
to disperse the polymer melt in the carrier fluid 104 as droplets
(i.e., the polymer emulsion 114). Without being limited by theory,
it is believed that, all other factors being the same, increasing
shear should decrease the size of the droplets of the polymer melt
in the carrier fluid 104. However, at some point there may be
diminishing returns on increasing shear and decreasing droplet size
or may be disruptions to the droplet contents that decrease the
quality of particles produced therefrom.
[0107] The melt emulsion 114 inside and/or outside the mixing
vessel is then cooled 116 to solidify the polymer droplets into
thermoplastic polymer particles (also referred to as solidified
thermoplastic polymer particles). The cooled mixture 118 can then
be treated 120 to isolate the thermoplastic polymer particles 122
from other components 124 (e.g., the carrier fluid 104, excess
emulsion stabilizer 106, and the like) and wash or otherwise purify
the thermoplastic polymer particles 122. The thermoplastic polymer
particles 122 comprise the thermoplastic polymer 102 and at least a
portion of the emulsion stabilizer 106 coating the outer surface of
the thermoplastic polymer particles 122. Emulsion stabilizers 106,
or a portion thereof, may be deposited as a uniform coating on the
thermoplastic polymer particles 122. In some instances, which may
be dependent upon non-limiting factors such as the temperature
(including cooling rate), the type of thermoplastic polymer 102,
and the types and sizes of emulsion stabilizers 106, the
nanoparticles of emulsion stabilizers 106 may become at least
partially embedded within the outer surface of thermoplastic
polymer particles 122 in the course of becoming associated
therewith. Even without embedment taking place, at least the
nanoparticles within emulsion stabilizers 106 may remain robustly
associated with thermoplastic polymer particles 122 to facilitate
their further use. In contrast, dry blending already formed
thermoplastic polymer particulates (e.g., formed by cryogenic
grinding or precipitation processes) with a flow aid like silica
nanoparticles does not result in a robust, uniform coating of the
flow aid upon the thermoplastic polymer particulates.
[0108] Advantageously, carrier fluids and washing solvents of the
systems and methods described herein (e.g., method 101) can be
recycled and reused. One skilled in the art will recognize any
necessary cleaning of used carrier fluid and solvent necessary in
the recycling process.
[0109] The thermoplastic polymer 102 and carrier fluid 104 should
be chosen such that at the various processing temperatures (e.g.,
from room temperature to process temperature) the thermoplastic
polymer 102 and carrier fluid 104 are immiscible. An additional
factor that may be considered is the differences in (e.g., a
difference or a ratio of) viscosity at process temperature between
the molten polyamide 102 and the carrier fluid 104. The differences
in viscosity may affect droplet breakup and particle size
distribution. Without being limited by theory, it is believed that
when the viscosities of the molten polyamide 102 and the carrier
fluid 104 are too similar, the circularity of the product as a
whole may be reduced where the particles are more ovular and more
elongated structures are observed.
[0110] Examples of thermoplastic polymers 102 include, but are not
limited to, polyamides, polyurethanes, polyethylenes,
polypropylenes, polyacetals, polycarbonates, polybutylene
terephthalate (PBT), polyethylene terephthalate (PET), polyethylene
naphthalate (PEN), polytrimethylene terephthalate (PTT),
polyhexamethylene terephthalate, polystyrenes, polyvinyl chlorides,
polytetrafluoroethenes, polyesters (e.g., polylactic acid),
polyethers, polyether sulfones, polyetherether ketones,
polyacrylates, polymethacrylates, polyimides, acrylonitrile
butadiene styrene (ABS), polyphenylene sulfides, vinyl polymers,
polyarylene ethers, polyarylene sulfides, polysulfones, polyether
ketones, polyamide-imides, polyetherimides, polyetheresters,
copolymers comprising a polyether block and a polyamide block (PEBA
or polyether block amide), grafted or ungrafted thermoplastic
polyolefins, functionalized or nonfunctionalized ethylene/vinyl
monomer polymer, functionalized or nonfunctionalized ethylene/alkyl
(meth)acrylates, functionalized or nonfunctionalized (meth)acrylic
acid polymers, functionalized or nonfunctionalized ethylene/vinyl
monomer/alkyl (meth)acrylate terpolymers, ethylene/vinyl
monomer/carbonyl terpolymers, ethylene/alkyl
(meth)acrylate/carbonyl terpolymers,
methylmethacrylate-butadiene-styrene (MBS)-type core-shell
polymers, polystyrene-block-polybutadiene-block-poly(methyl
methacrylate) (SBM) block terpolymers, chlorinated or
chlorosulphonated polyethylenes, polyvinylidene fluoride (PVDF),
phenolic resins, poly(ethylene/vinyl acetate)s, polybutadienes,
polyisoprenes, styrenic block copolymers, polyacrylonitriles,
silicones, and the like, and any combination thereof. Copolymers
comprising one or more of the foregoing may also be used in the
methods and systems of the present disclosure.
[0111] The thermoplastic polymers 102 in the compositions and
methods of the present disclosure may be elastomeric or
non-elastomeric. Some of the foregoing examples of thermoplastic
polymers 102 may be elastomeric or non-elastomeric depending on the
exact composition of the polymer. For example, polyethylene that is
a copolymer of ethylene and propylene may be elastomeric or not
depending on the amount of propylene in the polymer.
[0112] Thermoplastic elastomers generally fall within one of six
classes: styrenic block copolymers, thermoplastic polyolefin
elastomers, thermoplastic vulcanizates (also referred to as
elastomeric alloys), thermoplastic polyurethanes, thermoplastic
copolyesters, and thermoplastic polyamides (typically block
copolymers comprising polyamide). Examples of thermoplastic
elastomers can be found in Handbook of Thermoplastic Elastomers,
2nd ed., B. M. Walker and C. P. Rader, eds., Van Nostrand Reinhold,
N.Y., 1988. Examples of thermoplastic elastomers include, but are
not limited to, elastomeric polyamides, polyurethanes, copolymers
comprising a polyether block and a polyamide block (PEBA or
polyether block amide), methyl methacrylate-butadiene-styrene
(MBS)-type core-shell polymers,
polystyrene-block-polybutadiene-block-poly(methyl methacrylate)
(SBM) block terpolymers, polybutadienes, polyisoprenes, styrenic
block copolymers, and polyacrylonitriles), silicones, and the like.
Elastomeric styrenic block copolymers may include at least one
block selected from the group of: isoprene, isobutylene, butylene,
ethylene/butylene, ethylene-propylene, and
ethylene-ethylene/propylene. More specific elastomeric styrenic
block copolymer examples include, but are not limited to,
poly(styrene-ethylene/butylene),
poly(styrene-ethylene/butylene-styrene),
poly(styrene-ethylene/propylene),
styrene-ethylene/propylene-styrene),
poly(styrene-ethylene/propylene-styrene-ethylene-propylene),
poly(styrene-butadiene-styrene),
poly(styrene-butylene-butadiene-styrene), and the like, and any
combination thereof.
[0113] Examples of polyamides include, but are not limited to,
polycaproamide (nylon 6, polyamide 6, or PA6), poly(hexamethylene
succinamide) (nylon 4,6, polyamide 4,6, or PA4,6),
polyhexamethylene adipamide (nylon 6,6, polyamide 6,6, or PA6,6),
polypentamethylene adipamide (nylon 5,6, polyamide 5,6, or PA5,6),
polyhexamethylene sebacamide (nylon 6,10, polyamide 6,10, or
PA6,10), polyundecaamide (nylon 11, polyamide 11, or PA11),
polydodecaamide (nylon 12, polyamide 12, or PA12), and
polyhexamethylene terephthalamide (nylon 6T, polyamide 6T, or
PA6T), nylon 10,10 (polyamide 10,10 or PA10,10), nylon 10,12
(polyamide 10,12 or PA10,12), nylon 10,14 (polyamide 10,14 or
PA10,14), nylon 10,18 (polyamide 10,18 or PA10,18), nylon 6,18
(polyamide 6,18 or PA6,18), nylon 6,12 (polyamide 6,12 or PA6,12),
nylon 6,14 (polyamide 6,14 or PA6,14), nylon 12,12 (polyamide 12,12
or PA12,12), and the like, and any combination thereof.
Copolyamides may also be used.
[0114] Examples of copolyamides include, but are not limited to, PA
11/10,10, PA 6/11, PA 6,6/6, PA 11/12, PA 10,10/10,12, PA
10,10/10,14, PA 11/10,36, PA 11/6,36, PA 10,10/10,36, PA 6T/6,6,
and the like, and any combination thereof. A polyamide followed by
a first number comma second number is a polyamide having the first
number of backbone carbons between the nitrogens for the section
having no pendent .dbd.O and the second number of backbone carbons
being between the two nitrogens for the section having the pendent
.dbd.O. By way of nonlimiting example, nylon 6,10 is
[NH--(CH.sub.2).sub.6--NH--CO--(CH.sub.2).sub.8--CO].sub.n. A
polyamide followed by number(s) backslash number(s) are a copolymer
of the polyamides indicated by the numbers before and after the
backslash.
[0115] Examples of polyurethanes include, but are not limited to,
polyether polyurethanes, polyester polyurethanes, mixed polyether
and polyester polyurethanes, and the like, and any combination
thereof. Examples of thermoplastic polyurethanes include, but are
not limited to,
poly[4,4'-methylenebis(phenylisocyanate)-alt-1,4-butanediol/di(propylene
glycol)/polycaprolactone], ELASTOLLAN.RTM. 1190A (a polyether
polyurethane elastomer, available from BASF), ELASTOLLAN.RTM.
1190A10 (a polyether polyurethane elastomer, available from BASF),
and the like, and any combination thereof.
[0116] Compatibilizers may optionally be used to improve the
blending efficiency and efficacy thermoplastic polyester with one
or more thermoplastic polymers. Examples of polymer compatibilizers
include, but not limited to, PROPOLDER.TM. MPP2020 20
(polypropylene, available from Polygroup Inc.), PROPOLDER.TM.
MPP2040 40 (polypropylene, available from Polygroup Inc.),
NOVACOM.TM. HFS2100 (maleic anhydride functionalized high density
polyethylene polymer, available from Polygroup Inc.), KEN-REACT.TM.
CAPS.TM. L.TM. 12/L (organometallic coupling agent, available from
Kenrich Petrochemicals), KEN-REACT.TM. CAPOW.TM. L.TM. 12/H
(organometallic coupling agent, available from Kenrich
Petrochemicals), KEN-REACT.TM. LICA.TM. 12 (organometallic coupling
agent, available from Kenrich Petrochemicals), KEN-REACT.TM.
CAPS.TM. KPR.TM. 12/LV (organometallic coupling agent, available
from Kenrich Petrochemicals), KEN-REACT.TM. CAPOW.TM. KPR.TM. 12/H
(organometallic coupling agent, available from Kenrich
Petrochemicals), KEN-REACT.TM. titanates & zirconates
(organometallic coupling agent, available from Kenrich
Petrochemicals), VISTAMAXX.TM. (ethylene-propylene copolymers,
available from ExxonMobil), SANTOPRENE.TM. (thermoplastic
vulcanizate of ethylene-propylene-diene rubber and polypropylene,
available from ExxonMobil), VISTALON.TM. (ethylene-propylene-diene
rubber, available from ExxonMobil), EXACT.TM. (plastomers,
available from ExxonMobil) EXXELOR.TM. (polymer resin, available
from ExxonMobil), FUSABOND.TM. M603 (random ethylene copolymer,
available from Dow), FUSABOND.TM. E226 (anhydride modified
polyethylene, available from Dow), BYNEL.TM. 41E710 (coextrudable
adhesive resin, available from Dow), SURLYN.TM. 1650 (ionomer
resin, available from Dow), FUSABOND.TM. P353 (a chemically
modified polypropylene copolymer, available from Dow), ELVALOY.TM.
PTW (ethylene terpolymer, available from Dow), ELVALOY.TM. 3427AC
(a copolymer of ethylene and butyl acrylate, available from Dow),
LOTADER.TM. AX8840 (ethylene acrylate-based terpolymer, available
from Arkema), LOTADER.TM. 3210 (ethylene acrylate-based terpolymer,
available from Arkema), LOTADER.TM. 3410 (ethylene acrylate-based
terpolymer, available from Arkema), LOTADER.TM. 3430 (ethylene
acrylate-based terpolymer, available from Arkema), LOTADER.TM. 4700
(ethylene acrylate-based terpolymer, available from Arkema),
LOTADER.TM. AX8900 (ethylene acrylate-based terpolymer, available
from Arkema), LOTADER.TM. 4720 (ethylene acrylate-based terpolymer,
available from Arkema), BAXXODUR.TM. EC 301 (amine for epoxy,
available from BASF), BAXXODUR.TM. EC 311 (amine for epoxy,
available from BASF), BAXXODUR.TM. EC 303 (amine for epoxy,
available from BASF), BAXXODUR.TM. EC 280 (amine for epoxy,
available from BASF), BAXXODUR.TM. EC 201 (amine for epoxy,
available from BASF), BAXXODUR.TM. EC 130 (amine for epoxy,
available from BASF), BAXXODUR.TM. EC 110 (amine for epoxy,
available from BASF), styrenics, polypropylene, polyamides,
polycarbonate, EASTMAN.TM. G-3003 (a maleic anhydride grafted
polypropylene, available from Eastman), RETAIN.TM. (polymer
modifier available from Dow), AMPLIFY TY.TM. (maleic anhydride
grafted polymer, available from Dow), INTUNE.TM. (olefin block
copolymer, available from Dow), and the like and any combination
thereof.
[0117] The thermoplastic polymers 102 may have a melting point or
softening temperature of about 50.degree. C. to about 450.degree.
C. (or about 50.degree. C. to about 125.degree. C., or about
100.degree. C. to about 175.degree. C., or about 150.degree. C. to
about 280.degree. C., or about 200.degree. C. to about 350.degree.
C., or about 300.degree. C. to about 450.degree. C.).
[0118] The thermoplastic polymers 102 may have a glass transition
temperature (ASTM E1356-08(2014) with 10.degree. C./min ramping and
cooling rates) of about -50.degree. C. to about 400.degree. C. (or
about -50.degree. C. to about 0.degree. C., or about -25.degree. C.
to about 50.degree. C., or about 0.degree. C. to about 150.degree.
C., or about 100.degree. C. to about 250.degree. C., or about
150.degree. C. to about 300.degree. C., or about 200.degree. C. to
about 400.degree. C.).
[0119] The thermoplastic polymers 102 may optionally comprise an
additive. Typically, the additive would be present before addition
of the thermoplastic polymers 102 to the mixture 110. Therefore, in
the thermoplastic polymer melt droplets and resultant thermoplastic
polymer particles, the additive is dispersed throughout the
thermoplastic polymer. Accordingly, for clarity, this additive is
referred to herein as an "internal additive." The internal additive
may be blended with the thermoplastic polymer just prior to making
the mixture 110 or well in advance.
[0120] When describing component amounts in the compositions
described herein (e.g., the mixture 110 and thermoplastic polymer
particles 122), a weight percent based on the thermoplastic polymer
102 not inclusive of the internal additive. For example, a
composition comprising 1 wt % of emulsion stabilizer by weight of
100 g of a thermoplastic polymer 102 comprising 10 wt % internal
additive and 90 wt % thermoplastic polymer is a composition
comprising 0.9 g of emulsion stabilizer, 90 g of thermoplastic
polymer, and 10 g of internal additive.
[0121] The internal additive may be present in the thermoplastic
polymer 102 at about 0.1 wt % to about 60 wt % (or about 0.1 wt %
to about 5 wt %, or about 1 wt % to about 10 wt %, or about 5 wt %
to about 20 wt %, or about 10 wt % to about 30 wt %, or about 25 wt
% to about 50 wt %, or about 40 wt % to about 60 wt %) of the
thermoplastic polymer 102. For example, the thermoplastic polymer
102 may comprise about 70 wt % to about 85 wt % of a thermoplastic
polymer and about 15 wt % to about 30 wt % of an internal additive
like glass fiber or carbon fiber.
[0122] Examples of internal additives include, but are not limited
to, fillers, strengtheners, pigments, pH regulators, and the like,
and combinations thereof. Examples of fillers include, but are not
limited to, glass fibers, glass particles, mineral fibers, carbon
fiber, oxide particles (e.g., titanium dioxide and zirconium
dioxide), metal particles (e.g., aluminum powder), and the like,
and any combination thereof. Examples of pigments include, but are
not limited to, organic pigments, inorganic pigments, carbon black,
and the like, and any combination thereof.
[0123] The thermoplastic polymer 102 may be present in the mixture
110 at about 5 wt % to about 60 wt % (or about 5 wt % to about 25
wt %, or about 10 wt % to about 30 wt %, or about 20 wt % to about
45 wt %, or about 25 wt % to about 50 wt %, or about 40 wt % to
about 60 wt %) of the thermoplastic polymer 102 and carrier fluid
104 combined.
[0124] Suitable carrier fluids 104 have a viscosity at 25.degree.
C. of about 1,000 cSt to about 150,000 cSt (or about 1,000 cSt to
about 60,000 cSt, or about 40,000 cSt to about 100,000 cSt, or
about 75,000 cSt to about 150,000 cSt).
[0125] Examples of carrier fluids 104 include, but are not limited
to, silicone oil, fluorinated silicone oils, perfluorinated
silicone oils, polyethylene glycols, alkyl-terminal polyethylene
glycols (e.g., C1-C4 terminal alkyl groups like tetraethylene
glycol dimethyl ether (TDG)), paraffins, liquid petroleum jelly,
vison oils, turtle oils, soya bean oils, perhydrosqualene, sweet
almond oils, calophyllum oils, palm oils, parleam oils, grapeseed
oils, sesame oils, maize oils, rapeseed oils, sunflower oils,
cottonseed oils, apricot oils, castor oils, avocado oils, jojoba
oils, olive oils, cereal germ oils, esters of lanolic acid, esters
of oleic acid, esters of lauric acid, esters of stearic acid, fatty
esters, higher fatty acids, fatty alcohols, polysiloxanes modified
with fatty acids, polysiloxanes modified with fatty alcohols,
polysiloxanes modified with polyoxy alkylenes, and the like, and
any combination thereof. Examples of silicone oils include, but are
not limited to, polydimethylsiloxane, methylphenylpolysiloxane, an
alkyl modified polydimethylsiloxane, an alkyl modified
methylphenylpolysiloxane, an amino modified polydimethylsiloxane,
an amino modified methylphenylpolysiloxane, a fluorine modified
polydimethylsiloxane, a fluorine modified methylphenylpolysiloxane,
a polyether modified polydimethylsiloxane, a polyether modified
methylphenylpolysiloxane, and the like, and any combination
thereof. The carrier fluid 104 may have one or more phases. For
example, polysiloxanes modified with fatty acids and polysiloxanes
modified with fatty alcohols (preferably with similar chain lengths
for the fatty acids and fatty alcohols) may form a single-phase
carrier fluid 104. In another example, a carrier fluid 104
comprising a silicone oil and an alkyl-terminal polyethylene glycol
may form a two-phase carrier fluid 104.
[0126] The carrier fluid 104 may be present in the mixture 110 at
about 40 wt % to about 95 wt % (or about 75 wt % to about 95 wt %,
or about 70 wt % to about 90 wt %, or about 55 wt % to about 80 wt
%, or about 50 wt % to about 75 wt %, or about 40 wt % to about 60
wt %) of the thermoplastic polymer 102 and carrier fluid 104
combined.
[0127] In some instances, the carrier fluid 104 may have a density
of about 0.6 g/cm.sup.3 to about 1.5 g/cm.sup.3, and the
thermoplastic polymer 102 has a density of about 0.7 g/cm.sup.3 to
about 1.7 g/cm.sup.3, wherein the thermoplastic polymer has a
density similar, lower, or higher than the density of the carrier
fluid.
[0128] The emulsion stabilizers used in the methods and
compositions of the present disclosure may comprise nanoparticles
(e.g. oxide nanoparticles, carbon black, polymer nanoparticles, and
combinations thereof), surfactants, and the like, and any
combination thereof.
[0129] Oxide nanoparticles may be metal oxide nanoparticles,
non-metal oxide nanoparticles, or mixtures thereof. Examples of
oxide nanoparticles include, but are not limited to, silica,
titania, zirconia, alumina, iron oxide, copper oxide, tin oxide,
boron oxide, cerium oxide, thallium oxide, tungsten oxide, and the
like, and any combination thereof. Mixed metal oxides and/or
non-metal oxides, like aluminosilicates, borosilicates, and
aluminoborosilicates, are also inclusive in the term metal oxide.
The oxide nanoparticles may by hydrophilic or hydrophobic, which
may be native to the particle or a result of surface treatment of
the particle. For example, a silica nanoparticle having a
hydrophobic surface treatment, like dimethyl silyl, trimethyl
silyl, and the like, may be used in methods and compositions of the
present disclosure. Additionally, silica with functional surface
treatments like methacrylate functionalities may be used in methods
and compositions of the present disclosure. Unfunctionalized oxide
nanoparticles may also be suitable for use as well.
[0130] Commercially available examples of silica nanoparticles
include, but are not limited to, AEROSIL.RTM. particles available
from Evonik (e.g., AEROSIL.RTM. R812S (about 7 nm average diameter
silica nanoparticles having a hydrophobically modified surface and
a BET surface area of 260.+-.30 m.sup.2/g), AEROSIL.RTM. RX50
(about 40 nm average diameter silica nanoparticles having a
hydrophobically modified surface and a BET surface area of 35.+-.10
m.sup.2/g), AEROSIL.RTM. 380 (silica nanoparticles having a
hydrophilically modified surface and a BET surface area of
380.+-.30 m.sup.2/g)), and the like, and any combination
thereof.
[0131] Carbon black is another type of nanoparticle that may be
present as an emulsion stabilizer in the compositions and methods
disclosed herein. Various grades of carbon black will be familiar
to one having ordinary skill in the art, any of which may be used
herein. Other nanoparticles capable of absorbing infrared radiation
may be used similarly.
[0132] Polymer nanoparticles are another type of nanoparticle that
may be present as an emulsion stabilizer in the disclosure herein.
Suitable polymer nanoparticles may include one or more polymers
that are thermosetting and/or crosslinked, such that they do not
melt when processed by melt emulsification according to the
disclosure herein. High molecular weight thermoplastic polymers
having high melting or decomposition points may similarly comprise
suitable polymer nanoparticle emulsion stabilizers.
[0133] The nanoparticles may have an average diameter (D50 based on
volume) of about 1 nm to about 500 nm (or about 10 nm to about 150
nm, or about 25 nm to about 100 nm, or about 100 nm to about 250
nm, or about 250 nm to about 500 nm).
[0134] The nanoparticles may have a BET surface area of about 10
m.sup.2/g to about 500 m.sup.2/g (or about 10 m.sup.2/g to about
150 m.sup.2/g, or about 25 m.sup.2/g to about 100 m.sup.2/g, or
about 100 m.sup.2/g to about 250 m.sup.2/g, or about 250 m.sup.2/g
to about 500 m.sup.2/g).
[0135] Nanoparticles may be included in the mixture 110 at a
concentration of about 0.01 wt % to about 10 wt % (or about 0.01 wt
% to about 1 wt %, or about 0.1 wt % to about 3 wt %, or about 1 wt
% to about 5 wt %, or about 5 wt % to about 10 wt %) based on the
weight of the thermoplastic polymer 102.
[0136] Surfactants may be anionic, cationic, nonionic, or
zwitterionic. Examples of surfactants include, but are not limited
to, sodium dodecyl sulfate, sorbitan oleates,
poly[dimethylsiloxane-co-[3-(2-(2-hydroxyethoxy)ethoxy)propylmethylsiloxa-
ne], docusate sodium (sodium
1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate), and the like,
and any combination thereof. Commercially available examples of
surfactants include, but are not limited to, CALFAX.RTM. DB-45
(sodium dodecyl diphenyl oxide disulfonate, available from Pilot
Chemicals), SPAN.RTM. 80 (sorbitan maleate non-ionic surfactant),
MERPOL.RTM. surfactants (available from Stepan Company),
TERGITOL.TM. TMN-6 (a water-soluble, nonionic surfactant, available
from DOW), TRITON.TM. X-100 (octyl phenol ethoxylate, available
from SigmaAldrich), IGEPAL.RTM. CA-520 (polyoxyethylene (5)
isooctylphenyl ether, available from SigmaAldrich), BRIJ.RTM. S10
(polyethylene glycol octadecyl ether, available from SigmaAldrich),
and the like, and any combination thereof.
[0137] Surfactants may be included in the mixture 110 at a
concentration of about 0.01 wt % to about 10 wt % (or about 0.01 wt
% to about 1 wt %, or about 0.5 wt % to about 2 wt %, or about 1 wt
% to about 3 wt %, or about 2 wt % to about 5 wt %, or about 5 wt %
to about 10 wt %) based on the weight of the polyamide 102.
Alternatively, the mixture 110 may comprise no (or be absent of)
surfactant.
[0138] A weight ratio of nanoparticles to surfactant may be about
1:10 to about 10:1 (or about 1:10 to about 1:1, or about 1:5 to
about 5:1, or about 1:1 to about 10:1).
[0139] As described above, the components 102, 104, and 106 can be
added in any order and include mixing and/or heating during the
process of combining 108 the components 102, 104, and 106. For
example, the emulsion stabilizer 106 may first be dispersed in the
carrier fluid 104, optionally with heating said dispersion, before
adding the thermoplastic polymer 102. In another nonlimiting
example, the thermoplastic polymer 102 may be heated to produce a
polymer melt to which the carrier fluid 104 and emulsion stabilizer
106 are added together or in either order. In yet another
nonlimiting example, the thermoplastic polymer 102 and carrier
fluid 104 can be mixed at an a temperature greater than the melting
point or softening temperature of the thermoplastic polymer 102 and
at a shear rate sufficient enough to disperse the thermoplastic
polymer melt in the carrier fluid 104. Then, the emulsion
stabilizer 106 can be added to form the mixture 110 and maintained
at suitable process conditions for a set period of time.
[0140] Combining 108 the components 102, 104, and 106 in any
combination can occur in a mixing apparatus used for the processing
112 and/or another suitable vessel. By way of nonlimiting example,
the thermoplastic polymer 102 may be heated to a temperature
greater than the melting point or softening temperature of the
thermoplastic polymer 102 in the mixing apparatus used for the
processing 112, and the emulsion stabilizer 106 may be dispersed in
the carrier fluid 104 in another vessel. Then, said dispersion may
be added to the melt of the thermoplastic polymer 102 in the mixing
apparatus used for the processing 112.
[0141] The mixing apparatuses used for the processing 112 to
produce the melt emulsion 114 should be capable of maintaining the
melt emulsion 114 at a temperature greater than the melting point
or softening temperature of the thermoplastic polymer 102 and
applying a shear rate sufficient to disperse the polymer melt in
the carrier fluid 104 as droplets.
[0142] Examples of mixing apparatuses used for the processing 112
to produce the melt emulsion 114 include, but are not limited to,
extruders (e.g., continuous extruders, batch extruders, and the
like), stirred reactors, blenders, reactors with inline homogenizer
systems, and the like, and apparatuses derived therefrom.
[0143] Processing 112 and forming the melt emulsion 114 at suitable
process conditions (e.g., temperature, shear rate, and the like)
for a set period of time.
[0144] The temperature of processing 112 and forming the melt
emulsion 114 should be a temperature greater than the melting point
or softening temperature of the thermoplastic polymer 102 and less
than the decomposition temperature of any components 102, 104, and
106 in the mixture 110. For example, the temperature of processing
112 and forming the melt emulsion 114 may be about 1.degree. C. to
about 50.degree. C. (or about 1.degree. C. to about 25.degree. C.,
or about 5.degree. C. to about 30.degree. C., or about 20.degree.
C. to about 50.degree. C.) greater than the melting point or
softening temperature of the thermoplastic polymer 102 provided the
temperature of processing 112 and forming the melt emulsion 114 is
less than the decomposition temperature of any components 102, 104,
and 106 in the mixture 110.
[0145] The shear rate of processing 112 and forming the melt
emulsion 114 should be sufficiently high to disperse the polymer
melt in the carrier fluid 104 as droplets. Said droplets should
comprise droplets having a diameter of about 1000 .mu.m or less (or
about 1 .mu.m to about 1000 .mu.m, or about 1 .mu.m to about 50
.mu.m, or about 10 .mu.m to about 100 .mu.m, or about 10 .mu.m to
about 250 .mu.m, or about 50 .mu.m to about 500 .mu.m, or about 250
.mu.m to about 750 .mu.m, or about 500 .mu.m to about 1000
.mu.m).
[0146] The time for maintaining said temperature and shear rate for
processing 112 and forming the melt emulsion 114 may be 10 seconds
to 18 hours or longer (or 10 seconds to 30 minutes, or 5 minutes to
1 hour, or 15 minutes to 2 hours, or 1 hour to 6 hours, or 3 hours
to 18 hours). Without being limited by theory, it is believed that
a steady state of droplet sizes will be reached at which point
processing 112 can be stopped. That time may depend on, among other
things, the temperature, shear rate, thermoplastic polymer 102
composition, the carrier fluid 104 composition, and the emulsion
stabilizer 106 composition.
[0147] The melt emulsion 114 may then be cooled 116. Cooling 116
can be slow (e.g., allowing the melt emulsion to cool under ambient
conditions) to fast (e.g., quenching). For example, the rate of
cooling may range from about 10.degree. C./hour to about
100.degree. C./second to almost instantaneous with quenching (for
example in dry ice) (or about 10.degree. C./hour to about
60.degree. C./hour, or about 0.5.degree. C./minute to about
20.degree. C./minute, or about 1.degree. C./minute to about
5.degree. C./minute, or about 10.degree. C./minute to about
60.degree. C./minute, or about 0.5.degree. C./second to about
10.degree. C./second, or about 10.degree. C./second to about
100.degree. C./second).
[0148] During cooling, little to no shear may be applied to the
melt emulsion 114. In some instances, the shear applied during
heating may be applied during cooling.
[0149] The cooled mixture 118 resulting from cooling 116 the melt
emulsion 114 comprises solidified thermoplastic polymer particles
122 (or simply thermoplastic polymer particles) and other
components 124 (e.g., the carrier fluid 104, excess emulsion
stabilizer 106, and the like). The thermoplastic polymer particles
may be dispersed in the carrier fluid or settled in the carrier
fluid.
[0150] The cooled mixture 118 may then be treated 120 to the
separate thermoplastic polymer particles 122 (or simply
thermoplastic polymer particles 122) from the other components 124.
Suitable treatments include, but are not limited to, washing,
filtering, centrifuging, decanting, and the like, and any
combination thereof.
[0151] Solvents used for washing the thermoplastic polymer
particles 122 should generally be (a) miscible with the carrier
fluid 104 and (b) nonreactive (e.g., non-swelling and
non-dissolving) with the thermoplastic polymer 102. The choice of
solvent will depend on, among other things, the composition of the
carrier fluid and the composition of the thermoplastic polymer
102.
[0152] Examples of solvents include, but are not limited to,
hydrocarbon solvents (e.g., pentane, hexane, heptane, octane,
cyclohexane, cyclopentane, decane, dodecane, tridecane, and
tetradecane), aromatic hydrocarbon solvents (e.g., benzene,
toluene, xylene, 2-methyl naphthalene, and cresol), ether solvents
(e.g., diethyl ether, tetrahydrofuran, diisopropyl ether, and
dioxane), ketone solvents (e.g., acetone and methyl ethyl ketone),
alcohol solvents (e.g., methanol, ethanol, isopropanol, and
n-propanol), ester solvents (e.g., ethyl acetate, methyl acetate,
butyl acetate, butyl propionate, and butyl butyrate), halogenated
solvents (e.g., chloroform, bromoform, 1,2-dichloromethane,
1,2-dichloroethane, carbon tetrachloride, chlorobenzene, and
hexafluoroisopropanol), water, and the like, and any combination
thereof.
[0153] Solvent may be removed from the thermoplastic polymer
particles 122 by drying using an appropriate method such as
air-drying, heat-drying, reduced pressure drying, freeze drying, or
a hybrid thereof. The heating may be performed preferably at a
temperature lower than the glass transition point of the
thermoplastic polymer (e.g., about 50.degree. C. to about
150.degree. C.).
[0154] The thermoplastic polymer particles 122 after separation
from the other components 124 may optionally be further classified
to produce purified thermoplastic polymer particles 128. For
example, to narrow the particle size distribution (or reduce the
diameter span), the thermoplastic polymer particles 122 can be
passed through a sieve having a pore size of about 10 .mu.m to
about 250 .mu.m (or about 10 .mu.m to about 100 .mu.m, or about 50
.mu.m to about 200 .mu.m, or about 150 .mu.m to about 250
.mu.m).
[0155] In another example purification technique, the thermoplastic
polymer particles 122 may be washed with water to remove surfactant
while maintaining substantially all of the nanoparticles associated
with the surface of the thermoplastic polymer particles 122. In yet
another example purification technique, the thermoplastic polymer
particles 122 may be blended with additives to achieve a desired
final product. For clarity, because such additives are blended with
the thermoplastic particles 122 or other particles resultant from
the methods described herein after the particles are solidified,
such additives are referred to herein as "external additives."
Examples of external additives include flow aids, other polymer
particles, fillers, and the like, and any combination thereof.
[0156] In some instances, a surfactant used in making the
thermoplastic polymer particles 122 may be unwanted in downstream
applications. Accordingly, yet another example purification
technique may include at least substantial removal of the
surfactant from the thermoplastic polymer particles 122 (e.g., by
washing and/or pyrolysis).
[0157] The thermoplastic polymer particles 122 and/or purified
thermoplastic polymer particles 128 (referred to as particles
122/128) may be characterized by composition, physical structure,
and the like.
[0158] As described above, the emulsion stabilizers are at the
interface between the polymer melt and the carrier fluid. As a
result, when the mixture is cooled, the emulsion stabilizers remain
at, or in the vicinity of, said interface. Therefore, the structure
of the particles 122/128 is, in general, includes emulsion
stabilizers (a) dispersed on an outer surface of the particles
122/128 and/or (b) embedded in an outer portion (e.g., outer 1 vol
%) of the particles 122/128.
[0159] Further, where voids form inside the polymer melt droplets,
emulsion stabilizers 106 should generally be at (and/or embedded
in) the interface between the interior of the void and the
thermoplastic polymer. The voids generally do not contain the
thermoplastic polymer. Rather, the voids may contain, for example,
carrier fluid, air, or be void. The particles 122/128 may comprise
carrier fluid at about 5 wt % or less (or about 0.001 wt % to about
5 wt %, or about 0.001 wt % to about 0.1 wt %, or about 0.01 wt %
to about 0.5 wt %, or about 0.1 wt % to about 2 wt %, or about 1 wt
% to about 5 wt %) of the particles 122/128.
[0160] The thermoplastic polymer 102 may be present in the
particles 122/128 at about 90 wt % to about 99.5 wt % (or about 90
wt % to about 95 wt %, or about 92 wt % to about 97 wt %, or about
95 wt % to about 99.5 wt %) of the particles 122/128.
[0161] The emulsion stabilizers 106 may be present in the particles
122/128 at about 10 wt % or less (or about 0.01 wt % to about 10 wt
%, or about 0.01 wt % to about 1 wt %, or about 0.5 wt % to about 5
wt %, or about 3 wt % to about 7 wt %, or about 5 wt % to about 10
wt %) of the particles 122/128. When purified to at least
substantially remove surfactant or another emulsion stabilizer, the
emulsion stabilizers 106 may be present in the particles 128 at
less than 0.01 wt % (or 0 wt % to about 0.01 wt %, or 0 wt % to
0.001 wt %).
[0162] Upon forming thermoplastic particulates according to the
disclosure herein, at least a portion of the nanoparticles, such as
silica nanoparticles, may be disposed as a coating upon the outer
surface of the thermoplastic particulates. At least a portion of
the surfactant, if used, may be associated with the outer surface
as well. The coating may be disposed substantially uniformly upon
the outer surface. As used herein with respect to a coating, the
term "substantially uniform" refers to even coating thickness in
surface locations covered by the coating composition (e.g.,
nanoparticles and/or surfactant), particularly the entirety of the
outer surface. The emulsion stabilizers 106 may form a coating that
covers at least 5% (or about 5% to about 100%, or about 5% to about
25%, or about 20% to about 50%, or about 40% to about 70%, or about
50% to about 80%, or about 60% to about 90%, or about 70% to about
100%) of the surface area of the particles 122/128. When purified
to at least substantially remove surfactant or another emulsion
stabilizer, the emulsion stabilizers 106 may be present in the
particles 128 at less than 25% (or 0% to about 25%, or about 0.1%
to about 5%, or about 0.1% to about 1%, or about 1% to about 5%, or
about 1% to about 10%, or about 5% to about 15%, or about 10% to
about 25%) of the surface area of the particles 128. The coverage
of the emulsion stabilizers 106 on an outer surface of the
particles 122/128 may be determined using image analysis of the SEM
micrographs. The emulsion stabilizers 106 may form a coating that
covers at least 5% (or about 5% to about 100%, or about 5% to about
25%, or about 20% to about 50%, or about 40% to about 70%, or about
50% to about 80%, or about 60% to about 90%, or about 70% to about
100%) of the surface area of the particles 122/128. When purified
to at least substantially remove surfactant or another emulsion
stabilizer, the emulsion stabilizers 106 may be present in the
particles 128 at less than 25% (or 0% to about 25%, or about 0.1%
to about 5%, or about 0.1% to about 1%, or about 1% to about 5%, or
about 1% to about 10%, or about 5% to about 15%, or about 10% to
about 25%) of the surface area of the particles 128. The coverage
of the emulsion stabilizers 106 on an outer surface of the
particles 122/128 may be determined using image analysis of the SEM
micrographs
[0163] The particles 122/128 may have a D10 of about 0.1 .mu.m to
about 125 .mu.m (or about 0.1 .mu.m to about 5 .mu.m, about 1 .mu.m
to about 10 .mu.m, about 5 .mu.m to about 30 .mu.m, or about 1
.mu.m to about 25 .mu.m, or about 25 .mu.m to about 75 .mu.m, or
about 50 .mu.m to about 85 .mu.m, or about 75 .mu.m to about 125
.mu.m), a D50 of about 0.5 .mu.m to about 200 .mu.m (or about 0.5
.mu.m to about 10 .mu.m, or about 5 .mu.m to about 50 .mu.m, or
about 30 .mu.m to about 100 .mu.m, or about 30 .mu.m to about 70
.mu.m, or about 25 .mu.m to about 50 .mu.m, or about 50 .mu.m to
about 100 .mu.m, or about 75 .mu.m to about 150 .mu.m, or about 100
.mu.m to about 200 .mu.m), and a D90 of about 3 .mu.m to about 300
.mu.m (or about 3 .mu.m to about 15 .mu.m, or about 10 .mu.m to
about 50 .mu.m, or about 25 .mu.m to about 75 .mu.m, or about 70
.mu.m to about 200 .mu.m, or about 60 .mu.m to about 150 .mu.m, or
about 150 .mu.m to about 300 .mu.m), wherein D10<D50<D90. The
particles 122/128 may also have a diameter span of about 0.2 to
about 10 (or about 0.2 to about 0.5, or about 0.4 to about 0.8, or
about 0.5 to about 1.0, or about 1 to about 3, or about 2 to about
5, or about 5 to about 10). Without limitation, diameter span
values of 1.0 or greater are considered broad, and diameter spans
values of 0.75 or less are considered narrow. Without limitation,
diameter span values of 1.0 or greater are considered broad, and
diameter spans values of 0.75 or less are considered narrow.
[0164] In a first nonlimiting example, the particles 122/128 may
have a D10 of about 0.1 .mu.m to about 10 .mu.m, a D50 of about 0.5
.mu.m to about 25 .mu.m, and a D90 of about 3 .mu.m to about 50
.mu.m, wherein D10<D50<D90. Said particles 122/128 may have a
diameter span of about 0.2 to about 2.
[0165] In a second nonlimiting example, the particles 122/128 may
have a D10 of about 5 .mu.m to about 30 .mu.m, a D50 of about 30
.mu.m to about 70 .mu.m, and a D90 of about 70 .mu.m to about 120
.mu.m, wherein D10<D50<D90. Said particles 122/128 may have a
diameter span of about 1.0 to about 2.5.
[0166] In a third nonlimiting example, the particles 122/128 may
have a D10 of about 25 .mu.m to about 60 .mu.m, a D50 of about 60
.mu.m to about 110 .mu.m, and a D90 of about 110 .mu.m to about 175
.mu.m, wherein D10<D50<D90. Said particles 122/128 may have a
diameter span of about 0.6 to about 1.5.
[0167] In a fourth nonlimiting example, the particles 122/128 may
have a D10 of about 75 .mu.m to about 125 .mu.m, a D50 of about 100
.mu.m to about 200 .mu.m, and a D90 of about 125 .mu.m to about 300
.mu.m, wherein D10<D50<D90. Said particles 122/128 may have a
diameter span of about 0.2 to about 1.2.
[0168] In a fifth nonlimiting example, the particles 122/128 may
have a D10 of about 1 .mu.m to about 50 .mu.m (or about 5 .mu.m to
about 30 .mu.m, or about 1 .mu.m to about 25 .mu.m, or about 25
.mu.m to about 50 .mu.m), a D50 of about 25 .mu.m to about 100
.mu.m (or about 30 .mu.m to about 100 .mu.m, or about 30 .mu.m to
about 70 .mu.m, or about 25 .mu.m to about 50 .mu.m, or about 50
.mu.m to about 100 .mu.m), and a D90 of about 60 .mu.m to about 300
.mu.m (or about 70 .mu.m to about 200 .mu.m, or about 60 .mu.m to
about 150 .mu.m, or about 150 .mu.m to about 300 .mu.m), wherein
D10<D50<D90. The particles 122/128 may also have a diameter
span of about 0.4 to about 3 (or about 0.6 to about 2, or about 0.4
to about 1.5, or about 1 to about 3).
[0169] The particles 122/128 may have a circularity of about 0.7 or
greater (or about 0.7 to about 0.95, or about 0.9 to about 1.0, or
about 0.93 to about 0.99, or about 0.95 to about 0.99, or about
0.97 to about 0.99, or about 0.98 to 1.0).
[0170] The particles 122/128 may have an angle of repose of about
20.degree. to about 45.degree. (or about 25.degree. to about
35.degree., or about 30.degree. to about 40.degree., or about
35.degree. to about 45.degree.).
[0171] The particles 122/128 may have a Hausner ratio of about 1.0
to about 1.5 (or about 1.0 to about 1.2, or about 1.1 to about 1.3,
or about 1.2 to about 1.35, or about 1.3 to about 1.5).
[0172] The particles 122/128 may have a bulk density of about 0.3
g/cm.sup.3 to about 0.8 g/cm.sup.3 (or about 0.3 g/cm.sup.3 to
about 0.6 g/cm.sup.3, or about 0.4 g/cm.sup.3 to about 0.7
g/cm.sup.3, or about 0.5 g/cm.sup.3 to about 0.6 g/cm.sup.3, or
about 0.5 g/cm.sup.3 to about 0.8 g/cm.sup.3).
[0173] Depending on the temperature and shear rate of processing
112 and the composition and relative concentrations of the
components 102, 104, and 106, different shapes of the structures
that compose the particles 122/128 have been observed. Typically,
the particles 122/128 comprise substantially spherical particles
(having a circularity of about 0.97 or greater). However, other
structures included disc and elongated structures have been
observed in the particles 122/128. Therefore, the particles 122/128
may comprise one or more of: (a) substantially spherical particles
having a circularity of 0.97 or greater, (b) disc structures having
an aspect ratio of about 2 to about 10, and (c) elongated
structures having an aspect ratio of 10 or greater. Each of the
(a), (b), and (c) structures have emulsion stabilizers dispersed on
an outer surface of the (a), (b), and (c) structures and/or
embedded in an outer portion of the (a), (b), and (c) structures.
At least some of the (a), (b), and (c) structures may be
agglomerated. For example, the (c) elongated structures may be
laying on the surface of the (a) substantially spherical
particles.
[0174] The particles 122/128 may have a sintering window that is
within 10.degree. C., preferably within 5.degree. C., of the
sintering window of the thermoplastic polymer 102 (comprising one
or more PP-polyamides and optionally one or more other
thermoplastic polymers).
Applications of Thermoplastic Polymer Particles
[0175] The thermoplastic polymer particles described herein may be
utilized in 3-D print processes, particularly those employing
selective laser sintering to promote particulate consolidation. The
thermoplastic polymer particles of the present disclosure may
exhibit advantageous properties over polymer particulates having
irregular shapes or wider particulate distributions, such as those
available commercially. In nonlimiting examples, the thermoplastic
polymer particles of the present disclosure may undergo
consolidation at lower laser powers and afford a decreased extent
of void formation in an object produced by 3-D printing.
[0176] 3-D printing processes of the present disclosure may
comprise: depositing thermoplastic polymer particles of the present
disclosure upon a surface in a specified shape, and once deposited,
heating at least a portion of the thermoplastic polymer particles
to promote consolidation thereof and form a consolidated body
(object), such that the consolidated body has a void percentage of
about 1% or less after being consolidated. For example, heating and
consolidation of the thermoplastic polymer particles may take place
in a 3-D printing apparatus employing a laser, such that heating
and consolidation take place by selective laser sintering.
[0177] Any of the thermoplastic polymer particles disclosed herein
may be formulated in a composition suitable for 3-D printing.
Choice of the composition and type of elastomeric particulate may
be based upon various factors such as, but not limited to, the
laser power used for selective laser sinter, the type of object
being produced, and the intended use conditions for the object.
[0178] Examples of objects that may be 3-D printed using the
thermoplastic polymer particles of the present disclosure include,
but are not limited to, containers (e.g., for food, beverages,
cosmetics, personal care compositions, medicine, and the like),
shoe soles, toys, furniture parts and decorative home goods,
plastic gears, screws, nuts, bolts, cable ties, automotive parts,
medical items, prosthetics, orthopedic implants,
aerospace/aircraft-related parts, production of artifacts that aid
learning in education, 3D anatomy models to aid in surgeries,
robotics, biomedical devices (orthotics), home appliances,
dentistry, electronics, sporting goods, and the like.
[0179] Other applications for the thermoplastic particulates of the
present disclosure may include, but are not limited to, use as a
filler in paints and powder coatings, inkjet materials and
electrophotographic toners, and the like. In some instances, the
thermoplastic particulates may have other preferred characteristics
like diameter and span to be useful in said other applications.
Nonlimiting Example Embodiments
[0180] A first nonlimiting embodiment of the present disclosure is
a composition comprising: particles comprising a thermoplastic
polymer (e.g., thermoplastic elastomer) and an emulsion stabilizer
(e.g., nanoparticles and/or surfactant) associated with an outer
surface of the particles. The first nonlimiting embodiment may
include one or more of the following: Element 1: wherein the
emulsion stabilizer comprises nanoparticles and at least some of
the nanoparticles are embedded in the outer surface of the
particles; Element 2: wherein the thermoplastic polymer is present
at 90 wt % to 99.5 wt % of the particle; Element 3: wherein at
least some of the particles have a void comprising the emulsion
stabilizer at a void/thermoplastic polymer interface; Element 4:
Element 3 and wherein the emulsion stabilizer comprises
nanoparticles and the nanoparticles are embedded in the
void/thermoplastic polymer interface; Element 5: Element 3 and
wherein the void contains a carrier fluid having a viscosity at
25.degree. C. of 1,000 cSt to 150,000 cSt; Element 6: wherein the
particles further comprises elongated structures on the surface of
the particles, wherein the elongated structures comprises the
thermoplastic polymer with the emulsion stabilizer associated with
an outer surface of the elongated structures; Element 7: wherein
the emulsion stabilizer forms a coating that covers less than 5% of
the surface of the particles; Element 8: wherein the emulsion
stabilizer forms a coating that covers at least 5% of the surface
of the particles; Element 9: wherein the emulsion stabilizer forms
a coating that covers at least 25% of the surface of the particles;
Element 10: wherein the emulsion stabilizer forms a coating that
covers at least 50% of the surface of the particles; Element 11:
wherein the particles further comprise a carrier fluid having a
viscosity at 25.degree. C. of 1,000 cSt to 150,000 cSt; Element 12:
wherein the carrier fluid is present at about 5 wt % or less of the
particles; Element 13: wherein the nanoparticles have an average
diameter of 1 nm to 500 nm; Element 14: wherein the nanoparticles
have a BET surface area of 10 m.sup.2/g to 500 m.sup.2/g; Element
15: wherein the thermoplastic polymer is selected from the group
consisting of: polyamides, polyurethanes, polyethylenes,
polypropylenes, polyacetals, polycarbonates, polybutylene
terephthalate (PBT), polyethylene terephthalate (PET), polyethylene
naphthalate (PEN), polytrimethylene terephthalate (PTT),
polyhexamethylene terephthalate, polystyrenes, polyvinyl chlorides,
polytetrafluoroethenes, polyesters (e.g., polylactic acid),
polyethers, polyether sulfones, polyetherether ketones,
polyacrylates, polymethacrylates, polyimides, acrylonitrile
butadiene styrene (ABS), polyphenylene sulfides, vinyl polymers,
polyarylene ethers, polyarylene sulfides, polysulfones, polyether
ketones, polyamide-imides, polyetherimides, polyetheresters,
copolymers comprising a polyether block and a polyamide block (PEBA
or polyether block amide), grafted or ungrafted thermoplastic
polyolefins, functionalized or nonfunctionalized ethylene/vinyl
monomer polymer, functionalized or nonfunctionalized ethylene/alkyl
(meth)acrylates, functionalized or nonfunctionalized (meth)acrylic
acid polymers, functionalized or nonfunctionalized ethylene/vinyl
monomer/alkyl (meth)acrylate terpolymers, ethylene/vinyl
monomer/carbonyl terpolymers, ethylene/alkyl
(meth)acrylate/carbonyl terpolymers,
methylmethacrylate-butadiene-styrene (MBS)-type core-shell
polymers, polystyrene-block-polybutadiene-block-poly(methyl
methacrylate) (SBM) block terpolymers, chlorinated or
chlorosulphonated polyethylenes, polyvinylidene fluoride (PVDF),
phenolic resins, poly(ethylene/vinyl acetate)s, polybutadienes,
polyisoprenes, styrenic block copolymers, polyacrylonitriles,
silicones, and any combination thereof; Element 16: wherein a
melting point or softening temperature of the thermoplastic polymer
is 50.degree. C. to 450.degree. C.; Element 17: wherein the
particles have a D10 of about 0.5 .mu.m to about 125 .mu.m, a D50
of about 1 .mu.m to about 200 .mu.m, and a D90 of about 70 .mu.m to
about 300 .mu.m, wherein D10<D50<D90; Element 18: wherein the
particles have a diameter span of about 0.2 to about 10; Element
19: wherein the particles have a D10 of about 5 .mu.m to about 30
.mu.m, a D50 of about 30 .mu.m to about 70 .mu.m, and a D90 of
about 70 .mu.m to about 120 .mu.m, wherein D10<D50<D90;
Element 20: Element 19 and wherein the particles have a diameter
span of about 1.0 to about 2.5; Element 21: wherein the particles
have a D10 of about 25 .mu.m to about 60 .mu.m, a D50 of about 60
.mu.m to about 110 .mu.m, and a D90 of about 110 .mu.m to about 175
.mu.m, wherein D10<D50<D90; Element 22: Element 21 and
wherein the particles have a diameter span of about 0.6 to about
1.5; Element 23: wherein the particles have a D10 of about 75 .mu.m
to about 125 .mu.m, a D50 of about 100 .mu.m to about 200 .mu.m,
and a D90 of about 125 .mu.m to about 300 .mu.m, wherein
D10<D50<D90; Element 24: Element 23 and wherein the
solidified particles have a diameter span of about 0.2 to about 1;
Element 25: wherein the particles have a circularity of about 0.90
to about 1.0; and Element 26: wherein the particles have a Hausner
ratio of about 1.0 to about 1.5. Examples of combinations include,
but are not limited to, Element 1 in combination with one or more
of Elements 2-26; Element 3 (optionally in combination with Element
4 and/or Element 5) in combination with one or more of Elements 2
and 4-26; and two or more of Elements 1-15 in combination.
[0181] A second nonlimiting embodiment of the present disclosure is
a method comprising: mixing a mixture comprising a thermoplastic
polymer, an carrier fluid that is immiscible with the thermoplastic
polymer (e.g., thermoplastic elastomer), and emulsion stabilizer
(e.g., nanoparticles and/or surfactant) at a temperature greater
than a melting point or softening temperature of the thermoplastic
polymer and at a shear rate sufficiently high to disperse the
thermoplastic polymer in the carrier fluid; cooling the mixture to
below the melting point or softening temperature of the
thermoplastic polymer to form solidified particles comprising the
thermoplastic polymer and the emulsion stabilizer associated with
an outer surface of the solidified particles; and separating the
solidified particles from the carrier fluid. The first nonlimiting
embodiment may include one or more of the following: Element 1;
Element 2; Element 3; Element 4; Element 5; Element 6; Element 7;
Element 8; Element 9; Element 10; Element 11; Element 12; Element
13; Element 14; Element 15; Element 16; Element 17; Element 18;
Element 19; Element 20; Element 21; Element 22; Element 23; Element
24; Element 25; Element 26; Element 27: wherein the thermoplastic
polymer is present in the mixture at 5 wt % to 60 wt % of the
mixture; Element 28: wherein the emulsion stabilizer is present in
the mixture at 0.05 wt % to 5 wt % by weight of the thermoplastic
polymer; Element 29: wherein the carrier fluid is selected from the
group consisting of: silicone oil, fluorinated silicone oils,
perfluorinated silicone oils, polyethylene glycols, alkyl-terminal
polyethylene glycols, paraffins, liquid petroleum jelly, vison
oils, turtle oils, soya bean oils, perhydrosqualene, sweet almond
oils, calophyllum oils, palm oils, parleam oils, grapeseed oils,
sesame oils, maize oils, rapeseed oils, sunflower oils, cottonseed
oils, apricot oils, castor oils, avocado oils, jojoba oils, olive
oils, cereal germ oils, esters of lanolic acid, esters of oleic
acid, esters of lauric acid, esters of stearic acid, fatty esters,
higher fatty acids, fatty alcohols, polysiloxanes modified with
fatty acids, polysiloxanes modified with fatty alcohols,
polysiloxanes modified with polyoxy alkylenes, and any combination
thereof; Element 30: Element 29 and wherein the silicone oil is
selected from the group consisting of: polydimethylsiloxane,
methylphenylpolysiloxane, an alkyl modified polydimethylsiloxane,
an alkyl modified methylphenylpolysiloxane, an amino modified
polydimethylsiloxane, an amino modified methylphenylpolysiloxane, a
fluorine modified polydimethylsiloxane, a fluorine modified
methylphenylpolysiloxane, a polyether modified
polydimethylsiloxane, a polyether modified
methylphenylpolysiloxane, and any combination thereof; Element 31:
wherein the carrier fluid has a density of 0.6 g/cm.sup.3 to 1.5
g/cm.sup.3, wherein the thermoplastic polymer has a density of 0.7
g/cm.sup.3 to 1.7 g/cm.sup.3; Element 32: wherein mixing occurs in
an extrude; Element 33: wherein mixing occurs in a stirred reactor;
and Element 33: wherein the mixture further comprises a surfactant.
Example of combinations include, but are not limited to: those
described relative to the first nonlimiting embodiment; Element 1
in combination with one or more of Elements 27-33; Element 3 (and
optionally Element 4 and/or Element 5) in combination with one or
more of Elements 27-33; two or more of Elements 27-33 in
combination; and one or more of Elements 27-33 in combination with
one or more of Elements 1-26.
Clauses
[0182] Clause 1. A composition comprising: particles comprising a
thermoplastic polymer (e.g., thermoplastic elastomer) and an
emulsion stabilizer (e.g., nanoparticles and/or surfactant)
associated with an outer surface of the particles.
[0183] Clause 2. The composition of Clause 1, wherein the emulsion
stabilizer comprises nanoparticles and at least some of the
nanoparticles are embedded in the outer surface of the
particles.
[0184] Clause 3. The composition of Clause 1, wherein the
thermoplastic polymer is present at 90 wt % to 99.5 wt % of the
particle.
[0185] Clause 4. The composition of Clause 1, wherein at least some
of the particles have a void comprising the emulsion stabilizer at
a void/thermoplastic polymer interface.
[0186] Clause 5. The composition of Clause 4, wherein the emulsion
stabilizer comprises nanoparticles and the nanoparticles are
embedded in the void/thermoplastic polymer interface.
[0187] Clause 6. The composition of Clause 4, wherein the void
contains a carrier fluid having a viscosity at 25.degree. C. of
1,000 cSt to 150,000 cSt
[0188] Clause 7. The composition of Clause 1, wherein the particles
further comprises elongated structures on the surface of the
particles, wherein the elongated structures comprises the
thermoplastic polymer with the emulsion stabilizer associated with
an outer surface of the elongated structures.
[0189] Clause 8. The composition of Clause 1, wherein the emulsion
stabilizer forms a coating that covers less than 5% of the surface
of the particles.
[0190] Clause 9. The composition of Clause 1, wherein the emulsion
stabilizer forms a coating that covers at least 5% of the surface
of the particles.
[0191] Clause 10. The composition of Clause 1, wherein the emulsion
stabilizer forms a coating that covers at least 25% of the surface
of the particles.
[0192] Clause 11. The composition of Clause 1, wherein the emulsion
stabilizer forms a coating that covers at least 50% of the surface
of the particles.
[0193] Clause 12. The composition of Clause 1, wherein the
particles further comprise a carrier fluid having a viscosity at
25.degree. C. of 1,000 cSt to 150,000 cSt.
[0194] Clause 13. The composition of Clause 12, wherein the carrier
fluid is present at about 5 wt % or less of the particles.
[0195] Clause 14. The composition of Clause 1, wherein the
nanoparticles have an average diameter of 1 nm to 500 nm.
[0196] Clause 15. The method of Clause 1, wherein the nanoparticles
have a BET surface area of 10 m.sup.2/g to 500 m.sup.2/g.
[0197] Clause 16. The composition of Clause 1, wherein the
thermoplastic polymer is selected from the group consisting of:
polyamides, polyurethanes, polyethylenes, polypropylenes,
polyacetals, polycarbonates, polybutylene terephthalate (PBT),
polyethylene terephthalate (PET), polyethylene naphthalate (PEN),
polytrimethylene terephthalate (PTT), polyhexamethylene
terephthalate, polystyrenes, polyvinyl chlorides,
polytetrafluoroethenes, polyesters (e.g., polylactic acid),
polyethers, polyether sulfones, polyetherether ketones,
polyacrylates, polymethacrylates, polyimides, acrylonitrile
butadiene styrene (ABS), polyphenylene sulfides, vinyl polymers,
polyarylene ethers, polyarylene sulfides, polysulfones, polyether
ketones, polyamide-imides, polyetherimides, polyetheresters,
copolymers comprising a polyether block and a polyamide block (PEBA
or polyether block amide), grafted or ungrafted thermoplastic
polyolefins, functionalized or nonfunctionalized ethylene/vinyl
monomer polymer, functionalized or nonfunctionalized ethylene/alkyl
(meth)acrylates, functionalized or nonfunctionalized (meth)acrylic
acid polymers, functionalized or nonfunctionalized ethylene/vinyl
monomer/alkyl (meth)acrylate terpolymers, ethylene/vinyl
monomer/carbonyl terpolymers, ethylene/alkyl
(meth)acrylate/carbonyl terpolymers,
methylmethacrylate-butadiene-styrene (MBS)-type core-shell
polymers, polystyrene-block-polybutadiene-block-poly(methyl
methacrylate) (SBM) block terpolymers, chlorinated or
chlorosulphonated polyethylenes, polyvinylidene fluoride (PVDF),
phenolic resins, poly(ethylene/vinyl acetate)s, polybutadienes,
polyisoprenes, styrenic block copolymers, polyacrylonitriles,
silicones, and any combination thereof.
[0198] Clause 17. The composition of Clause 1, wherein a melting
point or softening temperature of the thermoplastic polymer is
50.degree. C. to 450.degree. C.
[0199] Clause 18. The composition of Clause 1, wherein the
particles have a D10 of about 0.5 .mu.m to about 125 .mu.m, a D50
of about 1 .mu.m to about 200 .mu.m, and a D90 of about 70 .mu.m to
about 300 .mu.m, wherein D10<D50<D90.
[0200] Clause 19. The composition of Clause 1, wherein the
particles have a diameter span of about 0.2 to about 10.
[0201] Clause 20. The composition of Clause 1, wherein the
particles have a D10 of about 5 .mu.m to about 30 .mu.m, a D50 of
about 30 .mu.m to about 70 .mu.m, and a D90 of about 70 .mu.m to
about 120 .mu.m, wherein D10<D50<D90.
[0202] Clause 21. The composition of Clause 20, wherein the
particles have a diameter span of about 1.0 to about 2.5.
[0203] Clause 22. The composition of Clause 1, wherein the
particles have a D10 of about 25 .mu.m to about 60 .mu.m, a D50 of
about 60 .mu.m to about 110 .mu.m, and a D90 of about 110 .mu.m to
about 175 .mu.m, wherein D10<D50<D90.
[0204] Clause 23. The composition of Clause 22, wherein the
particles have a diameter span of about 0.6 to about 1.5.
[0205] Clause 24. The composition of Clause 1, wherein the
particles have a D10 of about 75 .mu.m to about 125 .mu.m, a D50 of
about 100 .mu.m to about 200 .mu.m, and a D90 of about 125 .mu.m to
about 300 .mu.m, wherein D10<D50<D90.
[0206] Clause 25. The composition of Clause 24, wherein the
solidified particles have a diameter span of about 0.2 to about
1.2.
[0207] Clause 26. The composition of Clause 1, wherein the
particles have a circularity of about 0.90 to about 1.0.
[0208] Clause 27. The composition of Clause 1, wherein the
particles have a Hausner ratio of about 1.0 to about 1.5.
[0209] Clause 28. The composition of Clause 1, wherein the
nanoparticles comprise oxide nanoparticles.
[0210] Clause 29. The composition of Clause 1, wherein the
nanoparticles comprise carbon black.
[0211] Clause 30. The composition of Clause 1, wherein the
nanoparticles comprise polymer nanoparticles.
[0212] Clause 31. The composition of Clause 1, wherein the
thermoplastic polymer comprises a thermoplastic elastomer.
[0213] Clause 32. The composition of Clause 1, wherein the
thermoplastic polymer is a thermoplastic elastomer.
[0214] Clause 33. A method comprising: mixing a mixture comprising
a thermoplastic polymer (e.g., thermoplastic elastomer), an carrier
fluid that is immiscible with the thermoplastic polymer, and an
emulsion stabilizer at a temperature greater than a melting point
or softening temperature of the thermoplastic polymer and at a
shear rate sufficiently high to disperse the thermoplastic polymer
in the carrier fluid; cooling the mixture to below the melting
point or softening temperature of the thermoplastic polymer to form
solidified particles comprising the thermoplastic polymer and the
emulsion stabilizer associated with an outer surface of the
solidified particles; and separating the solidified particles from
the carrier fluid.
[0215] Clause 34. The method of Clause 33, wherein the emulsion
stabilizer comprises nanoparticles at least some of the
nanoparticles are embedded in the outer surface of the solidified
particles.
[0216] Clause 35. The method of Clause 33, wherein at least some of
the solidified particles have a void comprising the emulsion
stabilizer at a void/thermoplastic polymer interface.
[0217] Clause 36. The method of Clause 35, wherein the emulsion
stabilizer comprises nanoparticles and the nanoparticles are
embedded in the void/thermoplastic polymer interface.
[0218] Clause 37. The method of claim Clause 35, wherein the void
contains the carrier fluid.
[0219] Clause 38. The composition of Clause 33, wherein the
solidified particles further comprises elongated structures on the
surface of the solidified particles, wherein the elongated
structures comprises the thermoplastic polymer with the emulsion
stabilizer associated with an outer surface of the elongated
structures.
[0220] Clause 39. The composition of Clause 33, wherein the
emulsion stabilizer forms a coating that covers less than 5% of the
surface of the solidified particles.
[0221] Clause 40. The composition of Clause 33, wherein the
emulsion stabilizer forms a coating that covers at least 5% of the
surface of the solidified particles.
[0222] Clause 41. The composition of Clause 33, wherein the
emulsion stabilizer forms a coating that covers at least 25% of the
surface of the solidified particles.
[0223] Clause 42. The composition of Clause 33, wherein the
emulsion stabilizer forms a coating that covers at least 50% of the
surface of the solidified particles.
[0224] Clause 43. The method of Clause 33, wherein the
thermoplastic polymer is present in the mixture at 5 wt % to 60 wt
% of the mixture.
[0225] Clause 44. The method of Clause 33, wherein the emulsion
stabilizer is present in the mixture at 0.05 wt % to 5 wt % by
weight of the thermoplastic polymer.
[0226] Clause 45. The method of Clause 33, wherein the
nanoparticles have an average diameter of 1 nm to 500 nm.
[0227] Clause 46. The method of Clause 33, wherein the
thermoplastic polymer is selected from the group consisting of:
polyamides, polyurethanes, polyethylenes, polypropylenes,
polyacetals, polycarbonates, polybutylene terephthalate (PBT),
polyethylene terephthalate (PET), polyethylene naphthalate (PEN),
polytrimethylene terephthalate (PTT), polyhexamethylene
terephthalate, polystyrenes, polyvinyl chlorides,
polytetrafluoroethenes, polyesters (e.g., polylactic acid),
polyethers, polyether sulfones, polyetherether ketones,
polyacrylates, polymethacrylates, polyimides, acrylonitrile
butadiene styrene (ABS), polyphenylene sulfides, vinyl polymers,
polyarylene ethers, polyarylene sulfides, polysulfones, polyether
ketones, polyamide-imides, polyetherimides, polyetheresters,
copolymers comprising a polyether block and a polyamide block (PEBA
or polyether block amide), grafted or ungrafted thermoplastic
polyolefins, functionalized or nonfunctionalized ethylene/vinyl
monomer polymer, functionalized or nonfunctionalized ethylene/alkyl
(meth)acrylates, functionalized or nonfunctionalized (meth)acrylic
acid polymers, functionalized or nonfunctionalized ethylene/vinyl
monomer/alkyl (meth)acrylate terpolymers, ethylene/vinyl
monomer/carbonyl terpolymers, ethylene/alkyl
(meth)acrylate/carbonyl terpolymers,
methylmethacrylate-butadiene-styrene (MBS)-type core-shell
polymers, polystyrene-block-polybutadiene-block-poly(methyl
methacrylate) (SBM) block terpolymers, chlorinated or
chlorosulphonated polyethylenes, polyvinylidene fluoride (PVDF),
phenolic resins, poly(ethylene/vinyl acetate)s, polybutadienes,
polyisoprenes, styrenic block copolymers, polyacrylonitriles,
silicones, and any combination thereof.
[0228] Clause 47. The method of Clause 33, wherein the melting
point or softening temperature of the thermoplastic polymer is
50.degree. C. to 450.degree. C.
[0229] Clause 48. The method of Clause 33, wherein the carrier
fluid is selected from the group consisting of: silicone oil,
fluorinated silicone oils, perfluorinated silicone oils,
polyethylene glycols, alkyl-terminal polyethylene glycols,
paraffins, liquid petroleum jelly, vison oils, turtle oils, soya
bean oils, perhydrosqualene, sweet almond oils, calophyllum oils,
palm oils, parleam oils, grapeseed oils, sesame oils, maize oils,
rapeseed oils, sunflower oils, cottonseed oils, apricot oils,
castor oils, avocado oils, jojoba oils, olive oils, cereal germ
oils, esters of lanolic acid, esters of oleic acid, esters of
lauric acid, esters of stearic acid, fatty esters, higher fatty
acids, fatty alcohols, polysiloxanes modified with fatty acids,
polysiloxanes modified with fatty alcohols, polysiloxanes modified
with polyoxy alkylenes, and any combination thereof.
[0230] Clause 49. The method of claim 48, wherein the silicone oil
is selected from the group consisting of: polydimethylsiloxane,
methylphenylpolysiloxane, an alkyl modified polydimethylsiloxane,
an alkyl modified methylphenylpolysiloxane, an amino modified
polydimethylsiloxane, an amino modified methylphenylpolysiloxane, a
fluorine modified polydimethylsiloxane, a fluorine modified
methylphenylpolysiloxane, a polyether modified
polydimethylsiloxane, a polyether modified
methylphenylpolysiloxane, and any combination thereof.
[0231] Clause 50. The method of Clause 33, wherein the carrier
fluid has a viscosity at 25.degree. C. of 1,000 cSt to 150,000
cSt.
[0232] Clause 51. The method of Clause 33, wherein the carrier
fluid has a density of 0.6 g/cm.sup.3 to 1.5 g/cm.sup.3, wherein
the thermoplastic polymer has a density of 0.7 g/cm.sup.3 to 1.7
g/cm.sup.3.
[0233] Clause 52. The method of Clause 33, wherein mixing occurs in
an extruder.
[0234] Clause 53. The method of Clause 33, wherein mixing occurs in
a stirred reactor.
[0235] Clause 54. The method of Clause 33, wherein the mixture
further comprises a surfactant.
[0236] Clause 55. The method of Clause 33, wherein the solidified
particles have a D10 of about 0.5 .mu.m to about 125 .mu.m, a D50
of about 1 .mu.m to about 200 .mu.m, and a D90 of about 70 .mu.m to
about 300 .mu.m, wherein D10<D50<D90.
[0237] Clause 56. The method of Clause 33, wherein the solidified
particles have a diameter span of about 0.2 to about 10.
[0238] Clause 57. The method of Clause 33, wherein the solidified
particles have a D10 of about 5 .mu.m to about 30 .mu.m, a D50 of
about 30 .mu.m to about 70 .mu.m, and a D90 of about 70 .mu.m to
about 120 .mu.m, wherein D10<D50<D90.
[0239] Clause 58. The method of Clause 57, wherein the solidified
particles have a diameter span of about 1.0 to about 2.5.
[0240] Clause 59. The method of Clause 33, wherein the solidified
particles have a D10 of about 25 .mu.m to about 60 .mu.m, a D50 of
about 60 .mu.m to about 110 .mu.m, and a D90 of about 110 .mu.m to
about 175 .mu.m, wherein D10<D50<D90.
[0241] Clause 60. The method of Clause 59, wherein the solidified
particles have a diameter span of about 0.6 to about 1.5.
[0242] Clause 61. The method of Clause 33, wherein the solidified
particles have a D10 of about 75 .mu.m to about 125 .mu.m, a D50 of
about 100 .mu.m to about 200 .mu.m, and a D90 of about 125 .mu.m to
about 300 .mu.m, wherein D10<D50<D90.
[0243] Clause 62. The method of Clause 61, wherein the solidified
particles have a diameter span of about 0.2 to about 1.2.
[0244] Clause 63. The method of Clause 33, wherein the solidified
particles have a circularity of about 0.90 to about 1.0.
[0245] Clause 74. The method of Clause 33, wherein the solidified
particles have a Hausner ratio of about 1.0 to about 1.5.
[0246] Clause 65. The method of Clause 33, wherein the
nanoparticles comprise oxide nanoparticles.
[0247] Clause 66. The method of Clause 33, wherein the
nanoparticles comprise carbon black.
[0248] Clause 67. The method of Clause 33, wherein the
nanoparticles comprise polymer nanoparticles.
[0249] Clause 68. The method of Clause 33, wherein the
thermoplastic polymer comprises a thermoplastic elastomer.
[0250] Clause 69. The method of Clause 33, wherein the
thermoplastic polymer is a thermoplastic elastomer.
[0251] Unless otherwise indicated, all numbers expressing
quantities of ingredients, properties such as molecular weight,
process conditions, and so forth used in the present specification
and associated claims are to be understood as being modified in all
instances by the term "about." Accordingly, unless indicated to the
contrary, the numerical parameters set forth in the following
specification and attached claims are approximations that may vary
depending upon the desired properties sought to be obtained by the
embodiments of the present invention. At the very least, and not as
an attempt to limit the application of the doctrine of equivalents
to the scope of the claim, each numerical parameter should at least
be construed in light of the number of reported significant digits
and by applying ordinary rounding techniques.
[0252] One or more illustrative embodiments incorporating the
invention embodiments disclosed herein are presented herein. Not
all features of a physical implementation are described or shown in
this application for the sake of clarity. It is understood that in
the development of a physical embodiment incorporating the
embodiments of the present invention, numerous
implementation-specific decisions must be made to achieve the
developer's goals, such as compliance with system-related,
business-related, government-related and other constraints, which
vary by implementation and from time to time. While a developer's
efforts might be time-consuming, such efforts would be,
nevertheless, a routine undertaking for those of ordinary skill in
the art and having benefit of this disclosure.
[0253] While compositions and methods are described herein in terms
of "comprising" various components or steps, the compositions and
methods can also "consist essentially of" or "consist of" the
various components and steps.
[0254] To facilitate a better understanding of the embodiments of
the present invention, the following examples of preferred or
representative embodiments are given. In no way should the
following examples be read to limit, or to define, the scope of the
invention.
EXAMPLES
Example 1
[0255] Polyamide 6 Microparticles were Produced in a Haake
Small-Scale double screw extruder with high shear rotors. The
carrier fluid was PDMS oil of either 30,000 cSt or 60,000 cSt
viscosity at room temperature. The concentrations of components in
the final mixture in the extruder are provided in Table 1. The
order of addition of components to the extruder were either (a) the
carrier fluid was added to the extruder, brought to temperature,
and then room temperature polymer pellets added to the heated
carrier fluid in the extruder or (b) where the polymer pellets were
added to the extruder, brought to temperature, and then room
temperature carrier fluid added to the molten polymer in the
extruder. At temperature (see Table 1), the extruder was operated
at 200 rpm for 30 minutes. Then, the mixture was discharged from
the extruder onto a cold surface to provide rapid quench cooling.
During heating, at temperature, and cooling, the torque of the
extruder system was measured with no significant torque
detected.
TABLE-US-00001 TABLE 1 Sample 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9
wt % polymer 20 20 20 20 35 35 35 35 50 carrier fluid 30,000 30,000
60,000 60,000 60,000 30,000 30,000 60,000 30,000 visc. (cSt) wt %
carrier fluid 80 80 80 80 65 65 65 65 50 set temp. (.degree. C.)
220 230 220 230 230 230 220 220 225 actual temp. (.degree. C.) 227
236 227 236 236 236 227 227 232 order of addition (a) (a) (a) (a)
(a) (a) (a) (a) (b)
[0256] The resultant mixture was then filtered through a 90 mm
WHATMAN.RTM. #1 paper filter (available from SigmaAldrich) to
separate the polyamide 6 particles from the carrier fluid. The
particles were washed three times with 300 mL of ethyl acetate. The
particles were then allowed to air dry overnight in an aluminum pan
in a fume hood.
[0257] The polyamide 6 particles were then characterized for size
with a Malvern MASTERSIZER.TM. 3000 and morphology with SEM
micrographs.
TABLE-US-00002 TABLE 2 Sample D50 (.mu.m) Diameter Span SEM
Micrograph 1-1 64 1.35 FIG. 2 1-2 35 1.33 FIG. 3 1-3 38 0.92 FIG. 4
1-4 43 0.82 FIG. 5 1-5 76 0.65 FIG. 6 1-6 98 0.79 FIG. 7 1-7 104
0.75 FIG. 8 1-8 96 0.83 FIG. 9 1-9 100 0.60 FIG. 10
[0258] This example illustrated general trends of (a) increasing
oil viscosity decreases the particle size and the diameter span
(e.g., comparing 1-1 to 1-3 and comparing 1-6 to 1-5), (b)
increasing polymer loading increases the particle size and
decreases the diameter span (e.g., comparing 1-4 to 1-5 and
comparing 1-1 to 1-7), and (c) increasing processing temperature
decreases the particle size and the diameter span (e.g., comparing
1-8 to 1-5 and comparing 1-1 to 1-2).
[0259] Additionally, inductively coupled plasma was performed on
the particles having been digested in HNO.sub.3/HF/H.sub.2O.sub.2
mixture using a closed-vessel microwave or oven for digestionto
determine the silica content, which relates to the residual PDMS.
The amount of silica found in the nine samples ranged from about
234 ppm to about 374 ppm. For the sample with about 234 ppm of
silica, it is estimated that there is only about 0.62 g of PDMS
present per 1000 g of particles. Without being limited by theory,
it is believed that said PDMS is present primarily on the surface
of the particles.
Example 2
[0260] Polyamide 12 microparticles were produced in a 25 mm
twin-screw extruder (Werner & Pfleiderer ZSK-25). The carrier
fluid was PDMS oil with 10,000 cSt viscosity at room temperature.
The concentrations of components in the final mixture in the
extruder are provided in Table 3. The polymer pellets were added to
the extruder, brought to temperature, and then preheated carrier
fluid having AEROSIL.RTM. R812S silica nanoparticles dispersed
therein added to the molten polymer in the extruder. Other
operational parameters are provided in Table 3. Then the mixture
was discharged into a container and allowed to cool to room
temperature over several hours. The light scattering particle size
data is also provided in Table 3.
TABLE-US-00003 TABLE 3 Sample 2-1 2-2 2-3 2-4 2-5 2-6 Screw RPM 900
1100 1100 900 900 1100 wt % polyamide 12* 47 47 47 47 38 38 wt %
silica** 1.1 1.1 1.1 1.1 1.1 1.1 Temp. (.degree. C.) 230 230 250
250 230 230 D10 (.mu.m) 30.5 31.2 26.2 25.4 35.6 54.2 D50 (.mu.m)
57.8 50.3 38.1 38.5 72.8 111 D90 (.mu.m) 101 80.1 55.3 57.9 131 220
*relative total combined weight of PDMS oil and polyamide
**relative to polyamide
Example 3
[0261] ELASTOLLAN.RTM. 1190A10 thermoplastic polyurethane (TPU)
added to the 25 mm twin-screw extruder (Werner & Pfleiderer
ZSK-25), brought to temperature, and then preheated 10,000 cSt PDSM
oil having AEROSIL.RTM. RX50 silica nanoparticles dispersed therein
added to the molten polymer in the extruder. The extruder
conditions and results are presented in Table 4.
TABLE-US-00004 TABLE 4 Ex- truder Screw Temp wt % wt % D10 D50 D90
Sample RPM (.degree. C.) TPU* silica** Silica (.mu.m) (.mu.m)
(.mu.m) 3-1 1100 240 53 1.3 RX50 54.2 69.0 86.6 3-2 900 240 53 1.3
RX50 59.2 74.5 94.8 3-3 1100 240 53 1.3 RX50 57.6 75.3 97.8 3-4
1100 240 53 1.3 RX50 49.5 65.1 85.0 3-5 1100 240 42 2.1 RX50 26.3
41.9 65.1 3-6 1100 240 42 2.1 RX50 28.9 42.0 60.2 3-7 1100 240 50
1.00 RX50 56.5 76.3 103.0 3-8 1100 240 46 1.17 RX50 44.6 61.7 84.7
3-9 1100 260 46 1.17 RX50 38.2 46.5 56.5 3-10 1100 260 51 0.96 RX50
53.5 64.0 75.7 3-11 1100 260 53 0.59 R812S 21.3 26.1 32.3 3-12 1100
260 51 0.64 R812S 19.5 24.0 29.7 3-13 1100 240 48 0.72 R812S 15.2
25.0 38.8 3-14 1100 240 52 0.62 R812S 20.8 35.1 57.5 3-15 1100 240
53 0.39 R812S 44.3 59.8 80.5 3-16 1100 240 47 0.50 R812S 21 34.8
54.8 3-17 1100 260 54 0.37 R812S 35.6 43.0 51.7 *relative to total
combined weight of PDMS oil and TPU **relative to TPU
Example 4
[0262] A 1 L stirred reactor from Parr Instruments was used to
prepare polyamide 6 particles by melt emulsification. The reactor
was loaded with 20 wt % polyamide 6 and 80 wt % 10,000 cSt PDMS
oil. The mixture was then heated to 225.degree. C. while stirring
at 1000 rpm using a dual 4-blade propeller. After about 60 minutes,
the mixture was discharged from the reactor onto dry ice to quench
the mixture. The mixture was then filtered and washed to recover
the polymer particles. The resultant polymer particles were passed
through a 150-.mu.m sieve. Approximately, 40 wt % of the polyamide
6 loaded into the reactor passed through the 150-.mu.m sieve. FIG.
11 is an SEM micrograph of the particles after sieving, which
illustrates the range of particle sizes as large.
Example 5
[0263] A 2 L glass reactor from Buchi AG was used to prepare
polyamide 12 particles by melt emulsification. The reactor was
loaded with 1 wt % AEROSIL.RTM. R812S silica nanoparticles (by
weight of the polyamide 12 in the final mixture) in 10,000 cSt PDMS
oil. The mixture was heated to 200.degree. C. before adding 23 wt %
polyamide 12 pellets relative to the combined weight of the PDMS
oil and polyamide 12. The reactor was mixed at 500 rpm for 30
minutes. The resultant mixture was discharged and cooled to ambient
temperate at a rate of about 1.degree. C. to about 3.degree. C. per
minute. The mixture was then washed with heptane and filtered
through a 90 mm WHATMAN.RTM. #1 paper filter to recover the polymer
particles. The resultant polymer particles were air dried overnight
in a fume hood. The dried particles have a D50 of about 227 .mu.m,
and the dried particles passed through a 150-.mu.m sieve have a D50
of about 124 .mu.m.
Example 6
[0264] Polyamide 12 particles (Examples 6-1 to 6-44) were prepared
by melt emulsification in a 1 L glass kettle reactor. 10,000 cSt
PDMS oil, 23% polyamide 12 (from RTP, EMX-Grivory, or from Arkema)
relative to the combined weight of the PDMS oil and polyamide 12,
and a desired amount of silica nanoparticles (AEROSIL.RTM. R812S or
AEROSIL.RTM. RX50) by weight of polyamide 12 were added to the
glass kettle. The order of addition was either (c) PDMS oil and
silica nanoparticles mixed to a good dispersion then polyamide
added or (d) PDMS oil, polyamide, and silica nanoparticles added
before mixing. The nitrogen headspace purge was then turned on, and
the mixture heated to a desired temperature (e.g., 200.degree. C.,
210.degree. C., or 220.degree. C.) over 90 minutes at 260 rpm. Once
at temperature, the rotor speed was increased to a desired rpm.
Samples were taken at various times. Once complete, heating and
stirring were turned off, and the reactor was allowed to cool to
room temperature before discharging the mixture. The resultant
mixture was filtered and washed with heptane. The resultant
particles were allowed to air dry overnight in a fume hood.
Optionally, the dried particles were screened (scr) through a
150-.mu.m sieve. Table 5 lists the experimental details and
resultant particle properties.
[0265] For Samples 6-45 to 6-47, a 2 L stainless reactor from Buchi
AG was used to prepare polyamide 12 particles by melt
emulsification. The reactor was loaded with 0.67 wt % AEROSIL.RTM.
R812S silica nanoparticles (by weight of the polyamide 12 in the
final mixture) in 60,000 cSt PDMS oil and was sealed without N2
purge. The mixture was heated to 250.degree. C. at ramping rate of
3.68.degree. C./min before adding 30 wt % polyamide 12 pellets
relative to the combined weight of the PDMS oil and polyamide 12.
When the reactor temperature reached 245.degree. C., slowly opened
vent valve and purged reactor with N2 at flow rate of 2-3 scfh. The
reactor was mixed at 650 rpm for 60 minutes. The resultant mixture
was cooled down with gentle stirring at 50 rpm to less than
60.degree. C. and discharged. The process samples taken 40 min, 60
min and final room temp. were then washed with heptane and filtered
through a 90 mm WHATMAN.RTM. #1 paper filter to recover the polymer
particles. The resultant polymer particles were air dried overnight
in a fume hood. The dried particles have a D50 of about 21.3 .mu.m,
and the final dried particles passed through a 150-.mu.m sieve have
a D50 of about 21.5 .mu.m.
[0266] For Samples 6-48 to 6-50, a 2 L stainless reactor from Buchi
AG was used to prepare polyamide 12 particles by melt
emulsification. The reactor was loaded with 0.67 wt % AEROSIL.RTM.
R812S silica nanoparticles (by weight of the polyamide 12 in the
final mixture) in 60,000 cSt PDMS oil and was purged with N2 at
flow rate of 2-3 scfh. The mixture was heated to 250.degree. C. at
ramping rate of 3.68.degree. C./min before adding 30 wt % polyamide
12 pellets relative to the combined weight of the PDMS oil and
polyamide 12. The reactor was mixed at 650 rpm for 60 minutes. The
resultant mixture was cooled down with gentle stirring at 50 rpm to
less than 60.degree. C. and discharged. The process samples taken
50 min, 60 min time point and at room temp. were then washed with
heptane and filtered through a 90 mm WHATMAN.RTM. #1 paper filter
to recover the polymer particles. The final room temp. sample was
aggregated and the particle size was not measured. The resultant
polymer particles taken at 60 min were air dried overnight in a
fume hood. The dried particles have a D50 of about 25.8 .mu.m, and
the dried particles passed through a 150-.mu.m sieve have a D50 of
about 26.4 .mu.m.
[0267] For Samples 6-51 to 6-53, a 2 L stainless reactor from Buchi
AG was used to prepare polyamide 12 particles by melt
emulsification. The reactor was loaded with 0.67 wt % AEROSIL.RTM.
R812S silica nanoparticles (by weight of the polyamide 12 in the
final mixture) in 60,000 cSt PDMS oil and was purged with N2 at 2-3
flow rate of scfh. The mixture was heated to 250.degree. C. at
ramping rate of 5.68.degree. C./min before adding 30 wt % polyamide
12 pellets relative to the combined weight of the PDMS oil and
polyamide 12. The reactor was mixed at 650 rpm for 60 minutes. The
resultant mixture was cooled down with gentle stirring at 50 rpm to
less than 60.degree. C. and discharged. The process samples taken
at 60 min time point and at room temp. were then washed with
heptane and filtered through a 90 mm WHATMAN.RTM. #1 paper filter
to recover the polymer particles. The final room temp. sample was
aggregated and the particle size was not measured. The resultant
polymer particles taken at 60 min were air dried overnight in a
fume hood. The dried particles have a D50 of about 33.8 .mu.m, and
the dried particles passed through a 150-.mu.m sieve have a D50 of
about 34.9 .mu.m.
TABLE-US-00005 TABLE 5 Set Order Silica Screened Particle Size Not
Screened Particle Size Yield (wt %) Temp Time of (wt % and (.mu.m
or unitless) (.mu.m or unitless) Not Sample (.degree. C.) RPM (min)
Add. PA-12 type) D10 D50 D90 Span D10 D50 D90 Span Scr Scr 6-1 220
600 10 (c) EMS-Griv. 1% R812S 46.5 87.1 146 1.14 77.5 72.7 6-2 26
57.2 90.6 137 0.89 83.8 68.8 6-3 30 48.4 78.7 124 0.96 92.0 67.7
6-4 50 53.4 84.7 128 0.89 93.9 57.6 6-5 220 600 15 (c) EMS-Griv. 1%
R812S 34.9 76.3 131 1.99 90.8 74.3 6-6 220 1250 10 (c) EMS-Griv. 1%
R812S 16.2 43.8 103 1.98 92.7 71.4 6-7 20 19.3 44 95.5 1.73 94.3
69.6 6-8 30 20 44.4 97.2 1.74 96.4 71.9 6-9 40 21 43.8 92.7 1.64
87.2 80 6-10 RT 21.1 44.4 91.7 1.59 99.2 72.1 6-11 220 1250 40 (c)
EMS-Griv. 1% R812S 16.7 49.5 108 1.85 95.7 82.1 6-12 100 21.5 50.9
106 1.65 94.9 84.6 6-13 160 23.1 51.4 106 1.61 92.6 89.3 6-14 220
21.9 49.8 104 1.64 92.6 90.6 6-15 RT 22.9 52 108 1.64 94.3 91.1
6-16 220 1250 15 (c) RTP 1% R812S 12 46 104 1.41 6-17 220 1250 40
(d) RTP 0.33% R812S 46.7 8.35 139 1.02 97.3 77.4 6-18 90 53.1 89.5
144 1.02 95.4 78.7 6-19 210 1250 15 (d) RTP 0.33% R812S 44.2 70.7
112 0.96 94.7 80.8 6-20 40 46.1 71.7 111 0.90 92.6 8.6 6-21 90 49.8
78.9 124 0.94 88.7 90.6 6-22 RT 50.2 78.9 123 0.93 93.5 88.3 6-23
200 1250 15 (d) RTP 0.33% R812S 56.6 84.4 125 0.81 49.7 85.5 169
1.40 93.3 89.2 6-24 40 58 84.8 124 0.77 52.4 86.2 154 1.18 91.5
95.5 6-25 90 61.1 86.7 123 0.71 53.3 84.9 142 1.05 92.1 89.7 6-26
RT 59.4 84.6 121 0.73 54 89.4 166 1.25 93.3 91.8 6-27 220 1250 15
(d) RTP 1% R812S 16.2 43.9 95 1.79 17.8 54.8 300 5.15 96.0 83.3
6-28 40 19.8 46.3 96.7 1.66 19.7 53.3 263 4.57 95.4 97.9 6-29 90
21.1 47.7 106 1.79 21 49 220 4.05 96.4 84.8 6-30 RT 20.5 45.1 96.9
1.69 20.8 49.7 210 3.85 96.7 91.5 6-31 220 1250 15 (d) RTP 1% RX50
37.2 66.1 116 1.17 35.4 71.2 252 3.04 98.2 85.5 6-32 40 37.6 67.7
118 1.87 93.8 84.8 6-33 90 39.4 67.4 115 1.12 36.7 72.1 239 2.81
95.2 84.8 6-34 RT 36.4 65 113 1.18 36 73.2 254 2.98 96.1 88.5 6-35
220 1250 15 (d) RTP 0.33% RX50 101 125 135 0.94 101 125 135 0.43
94.7 29.7 6-35 40 99.5 128 164 0.51 108 172 271 0.95 94.7 25.5 6-36
90 102 129 162 0.46 116 175 265 0.85 94.7 21.2 6-37 RT 98.7 121 151
0.43 113 170 255 0.83 84.2 15.2 6-38 220 1250 40 (d) EMS-Griv.
0.33% R812S 56.6 79.9 112 0.688 51.4 87.6 216 1.884 90.2 81.8 6-39
90 60.7 87.1 124 0.729 56.5 95.5 218 1.688 90.5 77.6 6-40 RT 66.7
93.8 132 0.702 60.9 100 196 1.35 92.1 80.1 6-41 220 1250 15 (d)
Ark. 1% R812S 6-42 40 52.4 79.4 121 0.864 50 83.8 159 1.302 93.4
89.4 6-43 90 55.5 82.6 122 0.81 49.3 80 138 1.103 92.4 83.2 6-44 RT
6-45 250 650 40 RTP 0.67% R812S 14.5 20.3 28.5 0.69 14.1 20.1 28.5
0.72 98.42 96.6 6-46 60 12.6 20.0 31.1 0.93 12.1 19.8 32.4 1.02
96.97 94.2 6-47 RT 15.4 21.5 29.8 0.67 15.1 21.3 29.8 0.69 97.48
96.9 6-48 250 250 50 RTP 0.67% R812S 14.9 25.3 40.5 1.01 13.4 24.8
41.6 1.14 97.45 96.0 6-49 60 14.3 26.4 45.0 1.17 13.4 25.8 46.4
1.28 98.05 93.6 6-50 RT 6-51 250 650 40 RTP 0.67% R812S 6-52 60
19.2 34.9 59.1 1.15 17.8 33.8 58.7 1.21 97.86 91.3 6-53 RT "RT"
refers to once the mixture has cooled to reach room temperature.
Blank cells indicated values not measured.
[0268] FIG. 12 illustrates SEM micrographs for sample 6-4. FIG. 13
illustrates SEM micrographs for sample 6-10. FIG. 14 illustrates
SEM micrographs for sample 6-15. FIG. 15 illustrates SEM
micrographs for sample 6-26. FIG. 16 illustrates SEM micrographs
for sample 6-30. FIGS. 17-20 illustrate SEM micrographs for samples
6-31, 6-32, 6-33, and 6-34.
[0269] This example illustrates that decreasing the concentration
of silica nanoparticles in the mixture increases the particle size
but decreases the diameter span (e.g., comparing 6-17 through 6-18
to 6-28 through 6-29). Further, increasing the temperature decrease
the particle size but increase the diameter span (e.g., comparing
6-17 through 6-18, 6-20 through 6-21, and 6-24 through 6-25). It
also appears that the time of mixing beyond about 10 minutes has
minimal effect on the particle size and diameter span.
Example 7
[0270] SEM micrographs were taken of commercially available
polyamide particulate material used for 3D printing, see Table
6.
TABLE-US-00006 TABLE 6 Sample SEM Micrographs ADSINT .TM. PA11 FIG.
21 ADSINT .TM. PA12L FIG. 22 ADSINT .TM. PA12 FIGS. 23A and 23B
SINTRATEC .TM. PA12 FIG. 24
[0271] Comparing the SEM micrographs for the commercially available
samples to those of samples 6-4, 6-10, 6-15, 6-26, 6-30, 6-31,
6-32, 6-33, and 6-34 of Example 4, the particles produced by the
methods described herein have a greater circularity and higher
silica nanoparticle coverage on the surface of the polyamide
particles.
Example 8
[0272] Three sets of samples were prepared with polyamide 12 from
RTP. 10,000 cSt PDMS, 23 wt % polyamide 12 relative to the weight
of PDMS and polyamide combined, 1 wt % AEROSIL.RTM. R812S silica
nanoparticles relative to the weight of the polyamide, and
optionally surfactant (wt % relative to the weight of the
polyamide) were placed in a glass kettle reactor. The headspace was
purged with argon and the reactor was maintained under positive
argon pressure. The components were heated to over 220.degree. C.
over about 60 minutes with 300 rpm stirring. At temperature, the
rpm was increased to 1250 rpm. The process was stopped after 90
minutes and allowed to cool to room temperature while stirring. The
resultant mixture was filtered and washed with heptane. A portion
of the resultant particles was screened (scr) through a 150-.mu.m
sieve. Table 7 includes the additional components of the mixture
and properties of the resultant particles.
TABLE-US-00007 TABLE 7 Max Reactor Screened Particle Size Not
Screened Particle Size Temp. (.mu.m or unitless) (.mu.m or
unitless) Sample Surfactant (.degree. C.) D10 D50 D90 Span D10 D50
D90 Span 8-1 none 223 16.7 37.4 77.3 1.62 16.9 38.7 122 2.72 8-2
2.5% CALFAX .RTM. 226 44.2 67.7 105 0.90 41.4 68.1 131 1.32 DB-45
8-3 1% docusate 226 19.2 43.3 95.8 1.77 19.4 48.8 207 3.84
sodium
[0273] FIGS. 25 and 26 are the volume density particle size
distribution for the particles screened and not screened,
respectively.
Example 9
[0274] This example illustrates that the inclusion of surfactant
and the composition of said surfactant can be another tool used to
tailor the particle characteristics.
[0275] In this example, powder flow of polyurethane particulates
was characterized through sieving and angle of repose measurements.
The sieved yield of the polyurethane particulates was determined by
exposing a quantity of polyurethane particulates to a 150 .mu.m
U.S.A. Standard Sieve (ASTM E11) and determining the fraction by
mass of particulates passing through the sieve relative to the
total quantity of polyurethane particulates. The sieve was used
manually without particular conditions of duration of force. Angle
of repose measurements were performed using a Hosokawa Micron
Powder Characteristics Tester PT-R using ASTM D6393-14 "Standard
Test Method for Bulk Solids" Characterized by Carr Indices."
[0276] In this example, average particle size measurements and
particle size distributions were determined by optical digital
microscopy. The optical images were obtained using a Keyence
VHX-2000 digital microscope using version 2.3.5.1 software for
particle size analysis (system version 1.93). In some instances,
D.sub.10, D.sub.50 and D.sub.90 measurements were made using a
Malvern MASTERSIZER.TM. 3000 Aero S particle size analyzer, which
uses light scattering techniques for particle size measurement.
[0277] For light scattering techniques, glass bead control samples
with a diameter within the range of 15 .mu.m to 150 .mu.m under the
tradename Quality Audit Standards QAS4002.TM. obtained from Malvern
Analytical Ltd. may be used. Samples may be analyzed as dry powders
dispersed in air using the dry powder dispersion module of the
MASTERSIZER.TM. 3000 Aero S. Particle sizes may be derived using
the instrument software from a plot of volume density as a function
of size.
Comparative Example 9-1
[0278] To a 500 mL glass reactor, 160 g polydimethylsiloxane
(PSF-30000, Clearco) was added. The reactor was set to a stirring
rate of 200 rpm, and the temperature was raised to 190.degree. C.
under an atmosphere of nitrogen gas. Further heating to 200.degree.
C. was performed, at which point, 40 g thermoplastic polyurethane
pellets were added to the stirring polydimethylsiloxane. The
thermoplastic polyurethane was poly[4,4'-methylenebis(phenyl
isocyanate)-alt-1,4-butanediol/di(propylene
glycol)/polycaprolactone] with hardness Shore A 84 (Sigma-Aldrich).
Once the thermoplastic polyurethane pellets were fully combined
with the polydimethylsiloxane, the stirring rate was increased to
500 rpm and the temperature was maintained at 200.degree. C. for 60
minutes. Thereafter, stirring was discontinued and the resulting
slurry was allowed to cool to room temperature. The slurry was
washed twice with hexane, and thermoplastic polyurethane
particulates were obtained following vacuum filtration.
[0279] The thermoplastic polyurethane particulates were then passed
through a 150 .mu.m sieve, and particulates passing through the
sieve were characterized by optical imaging. FIG. 27 shows an
illustrative optical microscopy image at 150.times. magnification
of thermoplastic polyurethane particulates obtained in Comparative
Example 9-1. The average particle size was approximately 100 .mu.m
and a wide distribution of particle sizes was obtained.
Comparative Example 9-2
[0280] The thermoplastic polyurethane particulates from Comparative
Example 9-1 were collected after filtration but before sieving and
combined with 0.25 wt. % fumed silica particulates functionalized
with hexamethyldisilazane (AEROSIL.RTM. RX50). The thermoplastic
polyurethane particulates were then dry blended with the fumed
silica particulates using an SKM Mill for 30 seconds at a blending
rate of 170 rpm.
[0281] The dry-blended particulates were then passed through a 150
.mu.m sieve and characterized by optical imaging and SEM. FIG. 28
shows an illustrative optical microscopy image of thermoplastic
polyurethane particulates obtained in Comparative Example 9-2.
FIGS. 29A and 29B show illustrative SEM images of thermoplastic
polyurethane particulates obtained in Comparative Example 9-2 at
various magnifications. The average particle size was approximately
100 .mu.m and a wide distribution of particle sizes was obtained,
similar to that of Comparative Example 9-1. There was no evidence
of silica particle embedment upon the surface of the thermoplastic
polyurethane particulates. Moreover, there was no apparent
formation of a uniform silica coating upon the polyurethane
particulates
Example 9-1
[0282] Comparative Example 9-1 was repeated, except 0.25 wt. % of
fumed silica particulates functionalized with hexamethyldisilazane
(AEROSIL.RTM. R812S) was combined with the polydimethylsiloxane
prior to heating the reactor to temperature and adding the
thermoplastic polyurethane particulates.
[0283] The thermoplastic polyurethane particulates were then passed
through a 150 .mu.m sieve, and particulates passing through the
sieve were characterized by optical imaging. FIG. 30 shows an
illustrative optical microscopy image of thermoplastic polyurethane
particulates obtained in Example 9-1. The average particle size was
approximately 12.+-.16 .mu.m. FIG. 31 shows an illustrative
histogram of the particle sizes of thermoplastic polyurethane
particulates obtained in Example 9-1.
Example 9-2
[0284] Example 9-1 was repeated, except 1.00 wt. % of the same
fused silica particulates was used. In addition, the slurry was
washed three times with hexanes instead of twice.
[0285] The thermoplastic polyurethane particulates were then passed
through a 150 .mu.m sieve, and particulates passing through the
sieve were characterized by optical imaging. FIG. 32 shows an
illustrative optical microscopy image of thermoplastic polyurethane
particulates obtained in Example 9-2. The average particle size was
approximately 34.+-.19 .mu.m. FIG. 33 shows an illustrative
histogram of the particle sizes of thermoplastic polyurethane
particulates obtained in Example 9-2.
Example 9-3
[0286] Example 9-1 was repeated, except the type of fumed silica
particulates was changed to AEROSIL.RTM. RX50. In addition, the
slurry was washed four times with heptane instead of twice with
hexanes.
[0287] The thermoplastic polyurethane particulates were then passed
through a 150 .mu.m sieve, and particulates passing through the
sieve were characterized by optical imaging and SEM. FIG. 34 shows
an illustrative optical microscopy image of thermoplastic
polyurethane particulates obtained in Example 9-3. FIGS. 35A and
35B show illustrative SEM images of thermoplastic polyurethane
particulates obtained in Example 9-3 at various magnifications. The
average particle size by optical imaging was approximately 48.+-.20
.mu.m, and the angle of repose was 32.0.degree.. FIG. 36 shows an
illustrative histogram of the particle sizes of thermoplastic
polyurethane particulates obtained in Example 9-3.
[0288] The particle size distribution determined by the Malvern
Mastersizer particle size analyzer provided D.sub.10, D.sub.50 and
D.sub.90 values of 40.7 .mu.m, 68.2 .mu.m and 109 .mu.m,
respectively, thereby affording a span of 1.001.
Example 9-4
[0289] Example 9-1 was repeated, except the type of thermoplastic
polyurethane pellets was changed to ELASTOLLAN.RTM. 1190A obtained
from BASF. ELASTOLLAN.RTM. 1190A is a polyether polyurethane
elastomer with a hardness Shore A 90.
[0290] The thermoplastic polyurethane particulates were then passed
through a 150 .mu.m sieve, and particulates passing through the
sieve were characterized by optical imaging and SEM. FIG. 37 shows
an illustrative optical microscopy image of thermoplastic
polyurethane particulates obtained in Example 9-4. FIGS. 38A-D show
illustrative SEM images of thermoplastic polyurethane particulates
obtained in Example 9-4 at various magnifications. The average
particle size by optical imaging was approximately 68.+-.29 .mu.m,
and the angle of repose was 29.9.degree.. FIG. 39 shows an
illustrative histogram of the particle sizes of thermoplastic
polyurethane particulates obtained in Example 9-4.
[0291] The particle size distribution determined by the Malvern
Mastersizer particle size analyzer provided D.sub.10, D.sub.50 and
D.sub.90 values of 61.0 .mu.m, 95.6 .mu.m and 146 .mu.m,
respectively, thereby affording a span of 0.889.
Example 9-5
[0292] Example 9-4 was repeated, except processing was conducted at
one-half the scale of Example 9-4.
[0293] The thermoplastic polyurethane particulates were then passed
through a 150 .mu.m sieve, and particulates passing through the
sieve were characterized by optical imaging and SEM. FIG. 40 shows
an illustrative optical microscopy image of thermoplastic
polyurethane particulates obtained in Example 9-5. FIGS. 41A-41C
show illustrative SEM images of thermoplastic polyurethane
particulates obtained in Example 9-5 at various magnifications. The
average particle size by optical imaging was approximately 61.+-.17
.mu.m. FIG. 42 shows an illustrative histogram of the particle
sizes of thermoplastic polyurethane particulates obtained in
Example 9-5.
[0294] The particle size distribution determined by the Malvern
MASTERSIZER.TM. particle size analyzer provided D.sub.10, D.sub.50
and D.sub.90 values of 52.6 .mu.m, 71.7 .mu.m and 97.2 .mu.m,
respectively, thereby affording a span of 0.622.
[0295] Comparison of Results. Tables 8A and 8B below summarize the
formation conditions used for Comparative Examples 9-1 and 9-2 and
Examples 9-1 through 9-5 and the properties of the thermoplastic
polyurethane particulates obtained in each instance. Solids loading
was calculated by dividing the mass of thermoplastic polyurethane
by the combined mass of thermoplastic polyurethane and
polydimethylsiloxane.
TABLE-US-00008 TABLE 8A Comp. Comp. Example Example Example Example
9-1 9-2 9-1 9-2 Solids Loading 20% 20% 20% 20% Thermoplastic 40 g
40 g 40 g 80 g Polyurethane (TPU) Poly(dimethylsiloxane) 160 g 160
g 160 g 320 g (PDMS) PDMS Viscosity 30,000 cSt 30,000 cSt 30,000
cSt 30,000 cSt Fumed Silica None 40 nm 7 nm 7 nm (wt. %) (0.25%)
(0.25%) (1.00%) Blending Process Melt Emuls. Dry Blend Melt Emuls.
Melt Emuls. Reactor 500 mL 500 mL 500 mL 500 mL Kettle Kettle
Kettle Kettle Temperature 200.degree. C. 200.degree. C. 200.degree.
C. 200.degree. C. RPM 500 500 500 500 Reaction Time 60 min 60 min
60 min 60 min Washing Hexane x 2 Hexane x 2 Hexane x 2 Hexane x 3
Pre-Sieving Mass 96% 96% 70% 78% Recovery Sieved Yield (150 .mu.m)
Cannot sieve 0.8% 40% 43% Average Particle Size ~100 .mu.m ~100
.mu.m 12 .+-. 16 .mu.m 34 .+-. 19 .mu.m by Optical Microscopy
D.sub.10 (.mu.m) D.sub.50 (.mu.m) D.sub.90 (.mu.m) Span Digital
Microscope FIG. 27 FIG. 28 FIG. 30 FIG. 32 Images (150X) (100X)
(250X) (150X) SEM Images FIGS. 29A/29B Histogram FIG. 31 FIG. 33
Angle of repose
TABLE-US-00009 TABLE 8B Example Example Example 9-3 9-4 9-5 Solids
Loading 20% 20% 20% Thermoplastic 80 g 80 g 40 g Polyurethane (TPU)
Poly(dimethylsiloxane) 320 g 320 g 160 g (PDMS) PDMS Viscosity
30,000 cSt 30,000 cSt 30,000 cSt Fumed Silica 40 nm 40 nm 40 nm
(wt. %) (0.25%) (0.25%) (0.25%) Blending Process Melt Emuls. Melt
Emuls. Melt Emuls. Reactor 500 mL 500 mL 500 mL Kettle Kettle
Kettle Temperature 200.degree. C. 200.degree. C. 200.degree. C. RPM
500 500 500 Reaction Time 60 min 60 min 60 min Washing Heptane x 4
Heptane x 4 Heptane x 4 Pre-Sieving Mass 89-95% 97% 96% Recovery
Sieved Yield (150 .mu.m) 80-83% 73% 87% Average Particle Size 48
.+-. 20 .mu.m 68 .+-. 29 .mu.m 61 .+-. 17 .mu.m by Optical
Microscopy D.sub.10 (.mu.m) 40.7 61.0 52.6 D.sub.50 (.mu.m) 68.2
95.6 71.7 D.sub.90 (.mu.m) 109 146 97.2 Span 1.001 0.889 0.622
Digital Microscope FIG. 34 FIG. 37 FIG. 40 Images (150X) (150X)
(150X) SEM Images FIGS. FIGS. FIGS. 35A/35B 38A-38D 41A-41C
Histogram FIG. 36 FIG. 39 FIG. 42 Angle of repose 32.0.degree.
29.9.degree.
As shown in Tables 8A and 8B and the accompanying FIGS., there was
a wide particle size distribution and some particulate coalescence
in the absence of a fused silica emulsion stabilizer (Comparative
Examples 9-1 and 9-2). Different loadings and sizes of fused silica
particles afforded narrower particle size distributions and
variations in average particle size (Examples 9-1 through 9-3).
Different thermoplastic polyurethanes also led to variance in the
average particle size obtained (Examples 9-3 and 9-4). The
processing scale also impacted the particle size distribution as
well (Examples 9-4 and 9-5).
[0296] Comparing the SEM images, there was fairly uniform coverage
of silica nanoparticles upon the surface of the thermoplastic
polyurethane particulates obtained by melt emulsification (Examples
9-3 through 9-5; FIGS. 35A/10B, 38A-13D and 41A-41C). The
thermoplastic polyurethane particulates obtained in Example 9-5,
which had a narrower particle size distribution, had a more even
coverage/distribution of silica nanoparticles than did the
comparable thermoplastic polyurethane particulates prepared in
Example 9-4, which had a wider particle size distribution.
[0297] In contrast to thermoplastic polyurethane particulates
produced by melt emulsification with silica nanoparticles, dry
blending of thermoplastic polyurethane particulates with silica
nanoparticles resulted in little, if any, coverage of silica
nanoparticles on the thermoplastic polyurethane particulates
(Comparative Example 9-2; FIGS. 29A/29B).
[0298] Another comparative example of thermoplastic polyurethane
particulates is ADSINT TPU 90A NAT from ADVANC3D, which is a 3-D
printing composition. ADSINT TPU 90A NAT thermoplastic polyurethane
particulates have an irregular particulate shape, as shown in the
SEM images of FIGS. 43A-43E. Based on the SEM images of FIGS. 43B
and 43C there is an uneven distribution of emulsion stabilizers on
the surface of ADSINT TPU 90A particulates. Particulates that are
irregular in shape and have a rough surface tend to have an uneven
distribution of emulsion stabilizers on the surface, and
agglomeration in rough areas and crevices may occur, as shown in
the SEM images of FIGS. 43C and 43D. The cross-sectional SEM image
of FIG. 43E shows the presence of emulsion stabilizers in limited
areas with a non-uniform distribution around the particulate.
[0299] Substantially spherical particulates with a smooth surface,
as produced in Examples 9-1 through 9-5, may afford incorporation
of emulsion stabilizers in a homogeneous manner around the outer
surface of each particulate. Substantially homogeneous
incorporation of emulsion stabilizers upon the particulates may aid
in achieving uniform properties and consistent performance for the
corresponding bulk materials, such as powder flow characteristics
and processing properties.
Example 10
[0300] Selective laser sintering (SLS) was performed using a Snow
White SLS printer system (Sharebot). The thermoplastic polyurethane
particulates of Example 9-3 were deposited using the SLS printer
system in a 30 mm.times.30 mm square and then sintered under
various laser power conditions specified in Table 9 below. Void
percentage following sintering was calculated using the digital
microscope software.
TABLE-US-00010 TABLE 9 Laser Length .times. Power Scan Temp. Width
% Entry (%) Rate.sup.1 (.degree. C.) Comments (mm) Voids 1 20
40,000 108 No sintering. 2 25 40,000 108 Sintered. 30,162 .times.
0.098 Lots of powder 30,105 on backside. 3 30 40,000 108 Sintered.
29,930 .times. 0.58 Lots of powder 30,034 on backside. 4 35 40,000
108 Sintered. 30,234 .times. 0.13 Lots of powder 30,380 on
backside. 5 40 40,000 108 Sintered. 30,230 .times. 0.029 Lots of
powder 30,035 on backside. .sup.1Multiplying the reported scan rate
by 0.04 gives the scan rate in mm/s.
[0301] As shown, effective sintering was realized at a laser power
above 20%, up to a power of 40% (highest value tested) to afford
low-porosity materials having under 1% voids, many times under 0.1%
voids. The observed powder formation is believed to artificially
lower the amount of voids measured. In any event, the low void
percentage is characteristic of effective fusing of the
thermoplastic polyurethane particulates with one another. As a
representative example, FIG. 44 shows an optical image of the
printed product obtained from Entry 5 of Example 10.
Example 11
[0302] In this example, powder flow of polyurethane particulates
was characterized through sieving and angle of repose measurements.
The sieved yield of the polyurethane particulates was determined by
exposing a quantity of polyurethane particulates to a 150 .mu.m
U.S.A. Standard Sieve and determining the fraction by mass of
particulates passing through the sieve relative to the total
quantity of polyurethane particulates. The sieve was used manually
without particular conditions of duration of force. Angle of repose
measurements were performed using a Hosokawa Micron Powder
Characteristics Tester PT-R using ASTM D6393-14 "Standard Test
Method for Bulk Solids" Characterized by Can Indices."
[0303] In this example, average particle size (D.sub.50), D.sub.10
and D.sub.90 measurements were made using a Malvern MASTERSIZER.TM.
3000 Aero S particle size analyzer. Optical images were obtained
using a Keyence VHX-2000 digital microscope using version 2.3.5.1
software for particle size analysis (system version 1.93). An
average particle size was also obtained by processing the optical
image.
Comparative Example 11-1
[0304] To a 500 mL glass reactor, 160 g polydimethylsiloxane
(PSF-30000, Clearco) was added. The reactor was set to a stirring
rate of 350 rpm using an overhead stirrer, and the temperature was
raised to 190.degree. C. Further heating to 200.degree. C. was
performed, at which point, 40 g thermoplastic polyurethane pellets
were added to the stirring polydimethylsiloxane. The thermoplastic
polyurethane was poly[4,4'-methylenebis(phenyl
isocyanate)-alt-1,4-butanediol/di(propylene
glycol)/polycaprolactone] (Sigma-Aldrich). Once the thermoplastic
polyurethane pellets were fully combined with the
polydimethylsiloxane, the stirring rate was increased to 500 rpm
and the temperature was maintained at 200.degree. C. for 60
minutes. Thereafter, stirring was discontinued and the resulting
slurry was allowed to cool to room temperature. The slurry was
washed four times with heptane, and thermoplastic polyurethane
particulates were obtained following vacuum filtration.
[0305] The thermoplastic polyurethane particulates were then passed
through a 150 .mu.m sieve, and particulates passing through the
sieve were characterized by optical imaging. FIG. 45 shows an
illustrative optical microscopy image at 150.times. magnification
of thermoplastic polyurethane particulates obtained in Comparative
Example 11-1. The average particle size was 97.1 .mu.m and a wide
distribution of particle sizes was obtained (span=1.239). FIG. 46
shows an illustrative histogram of the particle sizes of
thermoplastic polyurethane particulates obtained in Comparative
Example 11-1.
Comparative Example 11-2
[0306] To a 500 mL glass reactor, 320 g polydimethylsiloxane
(PSF-30000, Clearco) was added along with 0.25 wt. % fumed silica
particulates functionalized with hexamethyldisilazane (AEROSIL.RTM.
RX50 from Evonik, 35.+-.10 m.sup.2/g BET surface area and 40 nm
average particle size). The reactor was set to a stirring rate of
200 rpm using an overhead stirrer, and the temperature was raised
to 190.degree. C. Further heating to 200.degree. C. was performed,
at which point, 80 g thermoplastic polyurethane pellets were added
to the stirring polydimethylsiloxane. The thermoplastic
polyurethane in this instance was ELASTOLLAN.RTM. 1190A, a
polyether polyurethane elastomer obtained from BASF. Once the
thermoplastic polyurethane pellets were fully combined with the
polydimethylsiloxane, the stirring rate was increased to 500 rpm
and the temperature was maintained at 200.degree. C. for 60
minutes. Thereafter, stirring was discontinued and the resulting
slurry was allowed to cool to room temperature. The slurry was
washed four times with hexanes, and thermoplastic polyurethane
particulates were obtained following vacuum filtration.
[0307] The thermoplastic polyurethane particulates were then passed
through a 150 .mu.m sieve, and particulates passing through the
sieve were characterized by optical imaging. FIG. 47 shows an
illustrative optical microscopy image at 150.times. magnification
of thermoplastic polyurethane particulates obtained in Comparative
Example 11-2. The average particle size was 95.6 .mu.m and a wide
distribution of particle sizes was obtained (span=0.892). The angle
of repose was 29.9.degree.. FIGS. 48A and 48B show illustrative SEM
images of thermoplastic polyurethane particulates obtained in
Comparative Example 11-2 at various magnifications. FIG. 49 shows
an illustrative histogram of the particle sizes of thermoplastic
polyurethane particulates obtained in Comparative Example 11-2.
Comparative Example 11-3
[0308] Comparative Example 11-1 was repeated, except 1.0 wt. % of
poly[dimethylsiloxane-co-[3-(2-(2-hydroxyethoxy)ethoxy)propylmethylsiloxa-
ne] surfactant was mixed with the PDMS before heating to the
processing temperature. FIG. 50 shows an illustrative optical
microscopy image at 100.times. magnification of thermoplastic
polyurethane particulates obtained in Comparative Example 11-3. The
average particle size was 123 .mu.m and a wide distribution of
particle sizes was obtained (span=0.977). FIG. 51 shows an
illustrative histogram of the particle sizes of thermoplastic
polyurethane particulates obtained in Comparative Example 11-3.
Comparative Example 11-4
[0309] Comparative Example 11-1 was repeated, except 2.5 wt. % SPAN
80 (sorbitan maleate non-ionic surfactant) was mixed with the PDMS
before heating to the processing temperature. FIG. 52 shows an
illustrative optical microscopy image at 100.times. magnification
of thermoplastic polyurethane particulates obtained in Comparative
Example 11-4. The average particle size was 139 .mu.m and a wide
distribution of particle sizes was obtained (span=0.811). FIG. 53
shows an illustrative histogram of the particle sizes of
thermoplastic polyurethane particulates obtained in Comparative
Example 11-4.
Example 11-1
[0310] Comparative Example 11-1 was repeated, except 0.25 wt. %
fumed silica particulates functionalized with hexamethyldisilazane
(AEROSIL.RTM. RX50) and 1.0 wt % sodium dodecylsulfate (SDS) were
mixed with the PDMS before heating to the processing temperature.
FIG. 54 shows an illustrative optical microscopy image at
300.times. magnification of thermoplastic polyurethane particulates
obtained in Example 11-1. The average particle size was 26.8 .mu.m
and a wide distribution of particle sizes was obtained
(span=1.251). FIG. 55 shows an illustrative histogram of the
particle sizes of thermoplastic polyurethane particulates obtained
in Example 11-1.
Example 11-2
[0311] Comparative Example 11-1 was repeated, except 0.25 wt. % of
fumed silica particulates functionalized with hexamethyldisilazane
(AEROSIL.RTM. RX50) and 2.5 wt. % docusate sodium (sodium
1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate also referred to
as dioctyl sodium sulfosuccinate) were combined with the
polydimethylsiloxane prior to heating the reactor to temperature
and adding the thermoplastic polyurethane polymer.
[0312] After isolation, the thermoplastic polyurethane particulates
were passed through a 150 .mu.m sieve, and particulates passing
through the sieve were characterized by optical imaging. FIG. 56
shows an illustrative optical microscopy image at 150.times.
magnification of thermoplastic polyurethane particulates obtained
in Example 11-2. The average particle size was 31.5 .mu.m and a
relatively narrow distribution of particle sizes was obtained
(span=0.859). The angle of repose was 38.2.degree.. FIG. 57 shows
an illustrative histogram of the particle sizes of thermoplastic
polyurethane particulates obtained in Example 11-2.
Example 11-3
[0313] Comparative Example 11-1 was repeated, except 1.0 wt. % of
fumed silica particulates functionalized with hexamethyldisilazane
(AEROSIL.RTM. RX50) and 1.0 wt. % docusate sodium were combined
with the polydimethylsiloxane prior to heating the reactor to
temperature and adding the thermoplastic polyurethane polymer.
[0314] After isolation, the thermoplastic polyurethane particulates
were passed through a 150 .mu.m sieve, and particulates passing
through the sieve were characterized by optical imaging. FIG. 58
shows an illustrative optical microscopy image at 150.times.
magnification of thermoplastic polyurethane particulates obtained
in Example 11-3. The average particle size was 51.2 .mu.m and a
relatively narrow distribution of particle sizes was obtained
(span=0.777). The angle of repose was 32.6.degree.. FIG. 59 shows
an illustrative histogram of the particle sizes of thermoplastic
polyurethane particulates obtained in Example 11-3.
Example 11-4
[0315] Comparative Example 11-1 was repeated, except 0.25 wt. % of
fumed silica particulates functionalized with hexamethyldisilazane
(AEROSIL.RTM. RX50) and 5 wt. % CALFAX.RTM. DB-45 were combined
with the polydimethylsiloxane prior to heating the reactor to
temperature and adding the thermoplastic polyurethane polymer.
[0316] After isolation, the thermoplastic polyurethane particulates
were passed through a 150 .mu.m sieve, and particulates passing
through the sieve were characterized by optical imaging. FIG. 60
shows an illustrative optical microscopy image at 150.times.
magnification of thermoplastic polyurethane particulates obtained
in Example 11-4. The average particle size was 121 .mu.m and a
relatively narrow distribution of particle sizes was obtained
(span=0.435). FIGS. 61A and 61B show illustrative SEM images of
thermoplastic polyurethane particulates obtained in Example 11-4 at
various magnifications. FIG. 62 shows an illustrative histogram of
the particle sizes of thermoplastic polyurethane particulates
obtained in Example 11-4.
Example 11-5
[0317] Comparative Example 11-1 was repeated, except 1.0 wt. % of
fumed silica particulates functionalized with hexamethyldisilazane
(AEROSIL.RTM. RX50) and 2.5 wt. % CALFAX.RTM. DB-45 were combined
with the polydimethylsiloxane prior to heating the reactor to
temperature and adding the thermoplastic polyurethane polymer.
[0318] After isolation, the thermoplastic polyurethane particulates
were passed through a 150 .mu.m sieve, and particulates passing
through the sieve were characterized by optical imaging. FIG. 63
shows an illustrative optical microscopy image at 150.times.
magnification of thermoplastic polyurethane particulates obtained
in Example 11-5. The average particle size was 62.9 .mu.m and a
relatively narrow distribution of particle sizes was obtained
(span=0.619). The angle of repose was 31.3.degree.. FIG. 64 shows
an illustrative histogram of the particle sizes of thermoplastic
polyurethane particulates obtained in Example 11-5.
[0319] Comparison of Results. Table 10 below summarizes the
formation conditions used for Comparative Examples 11-1 through
11-4 and the properties of the thermoplastic polyurethane
particulates obtained in each instance. Table 11 below summarizes
the formation conditions used for Examples 11-1 through 11-5 and
the properties of the thermoplastic polyurethane particulates
obtained in each instance.
TABLE-US-00011 TABLE 10 Comp. Comp. Comp. Comp. Example Example
Example Example 11-1 11-2 11-3 11-4 Solids Loading 20% 20% 20% 20%
Thermoplastic 40 g 80 g 40 g 40 g Polyurethane (TPU)
Poly(dimethylsiloxane) 160 g 320 g 160 g 160 g (PDMS) PDMS
Viscosity 30,000 cSt 30,000 cSt 30,000 cSt 30,000 cSt Fumed Silica
None 40 nm None None (wt. %) (0.25%) Surfactant None None
poly[dimethylsiloxane- Span 80 (wt. %) co-[3-(2-(2- (2.5%)
hydroxyethoxy)ethoxy) propylmethylsiloxane] (1.0%) Blending Process
Melt Emuls. Melt Emuls. Melt Emuls. Melt Emuls. Reactor 500 mL 500
mL 500 mL 500 mL Kettle Kettle Kettle Kettle Temperature
200.degree. C. 200.degree. C. 200.degree. C. 200.degree. C. RPM 500
500 500 500 Reaction Time 60 min 60 min 60 min 60 min Washing
Heptane x 4 Hexane x 4 Heptane x 4 Heptane x 4 Pre-Sieving Mass 95%
97% 97% 95% Recovery Sieved Yield (150 .mu.m) 50% 73% 43% 15%
Average Particle Size 97.1 .mu.m 95.6 .mu.m 123 .mu.m 139 .mu.m
Particle Size Span .sup. 1.239 .sup. 0.892 .sup. 0.977 .sup. 0.811
Digital Microscope FIG. 45 FIG. 47 FIG. 50 FIG. 52 Images (150X)
(100X) (100X) (100X) SEM Images FIGS. 48A/48B Histogram FIG. 46
FIG. 49 FIG. 51 FIG. 53 Angle of repose
TABLE-US-00012 TABLE 11 Example Example Example Example Example
11-1 11-2 11-3 11-4 11-5 Solids Loading 20% 20% 20% 20% 20%
Thermoplastic 40 g 40 g 40 g 40 g 40 g Polyurethane (TPU)
Poly(dimethylsiloxane) 160 g 160 g 160 g 160 g 160 g (PDMS) PDMS
Viscosity 30,000 cSt 30,000 cSt 30,000 cSt 30,000 cSt 30,000 cSt
Fumed Silica 40 nm 40 nm 40 nm 40 nm 40 nm (wt. %) (0.25%) (0.25%)
(1.0%) (0.25%) (1.0%) Surfactant Sodium Ducosate Ducosate CALFAX
.RTM. CALFAX .RTM. (wt. %) Dodecyl- sodium sodium DB-45 DB-45
sulfate (2.5%) (1%) (5.0%) (2.5%) (1.0%) Blending Process Melt
Emuls. Melt Emuls. Melt Emuls. Melt Emuls. Melt Emuls. Reactor 500
mL 500 mL 500 mL 500 mL 500 mL Kettle Kettle Kettle Kettle Kettle
Temperature 200.degree. C. 200.degree. C. 200.degree. C.
200.degree. C. 200.degree. C. RPM 500 500 500 500 500 Reaction Time
60 min 60 min 60 min 60 min 60 min Washing Heptane x 4 Heptane x 4
Heptane x 4 Heptane x 4 Heptane x 4 Pre-Sieving Mass 92% 87% 92%
93% 91% Recovery Sieved Yield (150 .mu.m) 97% 95% 95-99% 94% 91%
Average Particle Size 26.8 .mu.m 31.5 .mu.m 51.2 .mu.m 121 .mu.m
62.9 .mu.m Particle Size Span 1.251 0.859 0.777 0.435 0.619 Digital
Microscope FIG. 54 FIG. 56 FIG. 58 FIG. 60 FIG. 63 Images (300X)
(150X) (150X) (150X) (150X) SEM FIGS. 61A/61B Histogram FIG. 55
FIG. 57 FIG. 59 FIG. 62 FIG. 64 Angle of repose 49.3.degree.
38.2.degree. 32.6.degree. 31.3.degree.
The combination of silica nanoparticles and a sulfonate surfactant
was effective to form elastomeric particulates having a narrow size
distribution (span<0.9), and the post-sieving yield of the
original unsieved product was greater than 90% (Examples 11-2
through 11-5). A sulfate surfactant (Example 11-1) afforded a much
wider particle size distribution, in contrast, in spite having a
particle size similar to that produced with sulfonate surfactants.
Elastomeric particulates formed in the absence of silica
nanoparticles were considerably larger in size, and the yield
following sieving was low (Comparative Examples 11-1, 11-3, and
11-4).
[0320] FIG. 65 shows an illustrative particle size distribution
plot for Comparative Examples 11-1 and 11-4 and Example 11-3. As
shown, use of silica particles and a sulfonate surfactant (Example
11-3) afforded a much smaller particle size distribution.
Example 12
[0321] Selective laser sintering (SLS) was performed using a Snow
White SLS printer system (Sharebot). The thermoplastic polyurethane
particulates of Example 11-3 were deposited using the SLS printer
system in a 30 mm.times.30 mm square and then sintered under
various laser power conditions specified in Table 12 below. Void
percentage following sintering was calculated using the digital
microscope software. Little to no caking was seen following
sintering, which may be indicative of good single layer sintering
performance.
TABLE-US-00013 TABLE 12 Laser Length .times. Power Scan Temp. Width
% Entry (%) Rate.sup.1 (.degree. C.) Comments (mm) Voids 1 20
40,000 108 No sintering. 2 25 40,000 108 Sintered. 30,055 .times.
3.12 Very flexible. 29,880 3 30 40,000 108 Sintered. 30,037 .times.
1.49 Very flexible. 29.722 4 35 40,000 108 Sintered. 30,163 .times.
1.4 30,301 5 40 40,000 108 Sintered. 30,480 .times. 1.21 30,288 6
45 40,000 108 Sintered. 30,274 .times. 0.37 Powder on 30,520
backside. .sup.1Multiplying the reported scan rate by 0.04 give the
scan rate in mm/s.
[0322] As shown, effective sintering was realized at a laser power
above 20%, up to a power of 45% (highest value tested) to afford
low-porosity materials with a small quantity of voids, under 1.5%
voids at laser powers above 30%. The low void percentage is
characteristic of effective fusing of the thermoplastic
polyurethane particulates with one another. Powder formation in
Entry 6 is believed to artificially lower the amount of voids
measured.
[0323] Table 13 compares the laser sintering performance of the
thermoplastic polyurethane particulates of Example 11-3 against
those of Comparative Example 11-2 and commercial ADSINT
polyurethane particulates.
TABLE-US-00014 TABLE 13 % Voids Laser Comp. Power Scan Example
Example ADSINT Entry (%) Rate 11-3 11-2 TPU 1 20 40,000 No No No
sintering sintering sintering 2 25 40,000 3.12 No 5.07 sintering 3
30 40,000 1.49 No 4.28 sintering 4 35 40,000 1.4 4.48 2.65 5 40
40,000 1.21 0.38 1.68 6 45 40,000 0.37 0.84 No sintering
[0324] As shown, effective sintering was realized at a laser power
above 20%, up to a power of 45% (highest value tested), to afford
low-porosity materials when using the thermoplastic polyurethane
particles of Example 11-3. The laser sintering performance of the
thermoplastic polyurethane particulates of Example 11-3 was
considerably better than that of the commercial ADSINT
thermoplastic polyurethane particulates, as evaluated by the
porosity obtained. The laser sintering performance of the
thermoplastic polyurethane particulates of Example 11-3 was also
superior to that of Comparative Example 11-2 in terms of being
sinterable at lower laser powers and affording lower porosity
values in most cases. As a representative example, FIG. 66 shows an
optical image of the printed product obtained from Entry 5 of Table
12 (40% laser power).
Example 13
[0325] To a 500 mL glass kettle reactor equipped with a heating
mantle was added 140 g of PDMS (PSF-10000), 0.6 g (1.0 wt. %) of
AEROSIL RX50 silica nanoparticles, and 60 g of HYTREL.RTM. HTR 6108
pellets (glycol-modified polyethylene terephthalate, available from
DuPont). The reactor was set to a stirring rate of 200 RPM, and the
temperature was raised to 200.degree. C. over 30 minutes under
flowing argon purge. Once the temperature reached 200.degree. C.,
the stirring rate was increased to 1000 RPM. After 60 minutes,
heating and stirring were discontinued, and the slurry was allowed
to cool to room temperature. The slurry was then washed three times
with heptane, and the particulates were isolated by vacuum
filtration. After drying under vacuum overnight, the particulates
were then sieved through a 150 .mu.m filter. For the produced
particulates, the average particle size (determined via optical
microscopy) was 57 .mu.m, the span was 0.87, and the angle of
repose was 29.8.degree..
Example 14
[0326] To a 2 L Buchi reactor was added 871 g of PDMS (PSF-10000),
50 g of a PDMS/AEROSIL.RTM. RX50 slurry containing 2.9 g (0.5 wt.
%) AEROSIL.RTM. RX50 and 580 g of ELASTOLLAN 1190A10 polyurethane.
The reactor was purged with nitrogen, and stirring was conducted at
200 RPM. The jacket temperature was increased to 240.degree. C.
over 60 minutes. Once the reactor temperature had reached
200.degree. C., the stirring rate was increased to 500 RPM and the
nitrogen flow was turned off. The slurry was stirred for 30 minutes
at 240.degree. C. and then discharged while hot. After cooling, the
slurry was then washed twice with hexane, and the particulates were
isolated by vacuum filtration. After drying under vacuum overnight,
the particulates were then sieved through a 150 .mu.m filter. For
the produced particulates, the average particle size (determined
via optical microscopy) was 56 .mu.m, the span was 0.59, and the
angle of repose was 32.4.degree..
Example 15
[0327] Polypropylene microparticles were produced in a Haake
small-scale double screw extruder with high shear rotors. The
carrier fluid was PDMS oil of either 30,000 cSt or 60,000 cSt
viscosity at room temperature. The concentrations of components in
the final mixture in the extruder are provided in Table 15. The
order of addition of components to the extruder were either (a) the
carrier fluid was added to the extruder, brought to temperature,
and then room temperature polymer pellets added to the heated
carrier fluid in the extruder or (b) where the polymer pellets were
added to the extruder, brought to temperature, and then room
temperature carrier fluid added to the molten polymer in the
extruder. The polypropylene pellets were added at 30% solids
loading (that is, 18 g polypropylene in 60 g PDMS). The
polypropylene used was PP D115A polypropylene homopolymer,
available from Baskem USA. At temperature of either 225.degree. C.
or 250.degree. C. (see Table 14), the extruder was operated at
approximately 200 rpm for 30 minutes. Then, the mixture was
discharged from the extruder onto a cold surface to provide rapid
quench cooling. During heating, at temperature, and cooling, the
torque of the extruder system was measured. The resultant mixture
was then washed three times with 300 mL of heptane and filtered
through a 90 mm WHATMAN.RTM. #1 paper filter (available from
SigmaAldrich) to separate the polypropylene particles from the
carrier fluid. The particles were then allowed to air dry overnight
in an aluminum pan in a fume hood. The dried polypropylene
particles were characterized for morphology with SEM micrographs
and for size with a Malvern MASTERSIZER.TM. 3000 Aero S particle
size analyzer. Thermal properties were evaluated using Differential
Scanning calorimetry (DSC) to determine the melting temperature and
crystallization temperature. Inductively Coupled Plasma (ICP)
determined the residual silicone oil present on the particles.
[0328] In this example, powder flow of particulates was
characterized through sieving and angle of repose measurements. The
sieved yield of the particulates was determined by exposing a
quantity of particulates to a 250 mm U.S.A. Standard Sieve (ASTM
E11) and determining the fraction by mass of particulates passing
through the sieve relative to the total quantity of particulates.
The sieve was used manually without particular conditions of
duration of force. Angle of repose measurements were performed
using a Hosokawa Micron Powder Characteristics Tester PT-R using
ASTM D6393-14 "Standard Test Method for Bulk Solids" Characterized
by Carr Indices." The results are described in Table 14.
[0329] The SEM micrographs depict smooth round particles with a
fairly wide particle size distribution. The particles were
selectively laser sintered in a single layer on the Sharebot
SnowWhite SLS printer. Particles made using 30,000 cSt oil required
higher laser power to produce a robust sintered single layer
relative to the 60,000 cSt oil particles. Particles made using
60,000 cSt oil showed extreme edge curl as laser power
increased.
TABLE-US-00015 TABLE 14 Example Ex 15-1 Ex 15-2 Ex 15-3 Ex 15-4
PDMS Viscosity 30,000 cSt 60,000 cSt 60,000 cSt 30,000 cSt
Temperature 250.degree. C. 250.degree. C. 225.degree. C.
225.degree. C. Percent Sieved Yield 62% 65% 71% 78% (thru 250 .mu.m
sieve) D10 (.mu.m) sieved 33.0 25.8 21.8 36.4 D50 (.mu.m) sieved
66.9 47.2 40.8 65.7 D90 (.mu.m) sieved 118 84.9 72.4 110 Span 1.27
1.25 1.24 1.12 Angle of Repose (.degree.) 42.7 42.3 40.2 36.1
Melting 164.degree. C. 163.degree. C. 164.degree. C. 162.degree. C.
Temperature (Tm) Crystallization 120.degree. C. 114.degree. C.
111.degree. C. 113.degree. C. Temperature (Tc) Sintering Window
44.degree. C. 49.degree. C. 53.degree. C. 49.degree. C. ICP--Si
825.4 ppm 807.25 ppm 433.25 ppm 555.35 ppm Sintering Temperature
115.degree. C. 115.degree. C. 115.degree. C. 115.degree. C. Laser
Power Range 60-80% 45-65% 50-65% 55-80%
Example 16
[0330] Polyamide 12 microparticles were produced in a 25 mm
twin-screw extruder (Werner & Pfleiderer ZSK-25). The carrier
fluid was PDMS oil with 60,000 cSt viscosity at room temperature.
The concentrations of components in the final mixture in the
extruder are provided in Table 15. The polymer pellets were added
to the extruder, brought to temperature, and then preheated carrier
fluid having silica nanoparticles dispersed therein added to the
molten polymer in the extruder. Other operational parameters are
provided in Table 15. Then, the mixture was discharged into a
container and allowed to cool to room temperature over several
hours. The light scattering particle size data is also provided in
Table 15.
TABLE-US-00016 TABLE 15 Ex- truder Screw Temp wt % wt % D10 D50 D90
Sample RPM (.degree. C.) PA* silica** Silica (.mu.m) (.mu.m)
(.mu.m) 16-1 1000 280 45% 0.20% R812S 38.6 60.2 93.2 16-2 1000 280
45% 0.20% R812S 31.5 47.9 72.1 16-3 1000 280 45% 0.10% R812S 24.7
39.3 62.8 16-4 250 280 45% 0.10% R812S 31 48.4 75.6 16-5 1000 280
35% 0.10% R812S 19.9 35 62.6 16-6 1000 280 35% 0.75% X24*** 15.9
27.7 54.1 16-7 1000 280 40% 0.75% X24 19.2 32.3 60.5 16-8 1000 270
30% 0.25% R812S 21.6 34.4 53.7 16-9 1000 290 30% 0.25% R812S 16.8
29.7 53.7 16-10 1000 290 30% 0.75% X24 17 29.6 52.6 16-11 1000 270
30% 0.75% X24 17.5 30.1 54.2 16-12 250 250 30% 0.50% R812S 23.1
36.9 57.8 16-13 1000 250 30% 0.50% R812S 20.6 34.1 56.4 16-14 500
250 30% 0.50% R812S 22.9 39.8 71 16-15 500 250 30% 0.50% R812S 21.3
36.6 63.2 16-16 250 290 30% 1% R812S 16 25.3 39 16-17 1000 290 30%
1% R812S 14.5 22 33.1 16-18 250 250 30% 1% R812S 21.3 33 50.6 16-19
1000 250 30% 1% R812S 18.6 28.3 43.4 *relative to the total
combined weight of PDMS oil and polyamide **relative to the weight
of polyamide ***X24 is a silica powder available from ShinEtsu
having an average particle size of 0.1 .mu.m, a specific gravity of
1.8, and a water content of 2%.
[0331] Therefore, the present invention is well adapted to attain
the ends and advantages mentioned as well as those that are
inherent therein. The particular embodiments disclosed above are
illustrative only, as the present invention may be modified and
practiced in different but equivalent manners apparent to those
skilled in the art having the benefit of the teachings herein.
Furthermore, no limitations are intended to the details of
construction or design herein shown, other than as described in the
claims below. It is therefore evident that the particular
illustrative embodiments disclosed above may be altered, combined,
or modified and all such variations are considered within the scope
and spirit of the present invention. The invention illustratively
disclosed herein suitably may be practiced in the absence of any
element that is not specifically disclosed herein and/or any
optional element disclosed herein. While compositions and methods
are described in terms of "comprising," "containing," or
"including" various components or steps, the compositions and
methods can also "consist essentially of" or "consist of" the
various components and steps. All numbers and ranges disclosed
above may vary by some amount. Whenever a numerical range with a
lower limit and an upper limit is disclosed, any number and any
included range falling within the range is specifically disclosed.
In particular, every range of values (of the form, "from about a to
about b," or, equivalently, "from approximately a to b," or,
equivalently, "from approximately a-b") disclosed herein is to be
understood to set forth every number and range encompassed within
the broader range of values. Also, the terms in the claims have
their plain, ordinary meaning unless otherwise explicitly and
clearly defined by the patentee. Moreover, the indefinite articles
"a" or "an," as used in the claims, are defined herein to mean one
or more than one of the element that it introduces.
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