U.S. patent application number 17/201731 was filed with the patent office on 2021-09-09 for methods for reactive three-dimensional printing by extrusion.
The applicant listed for this patent is PPG Industries Ohio, Inc., UT-Battelle, LLC. Invention is credited to William G. Carter, Susan F. Donaldson, David R. Fenn, Cynthia Kutchko, Kurt G. Olson, Orlando Rios, Reza M. Rock, Hao Sun.
Application Number | 20210277263 17/201731 |
Document ID | / |
Family ID | 1000005599487 |
Filed Date | 2021-09-09 |
United States Patent
Application |
20210277263 |
Kind Code |
A1 |
Fenn; David R. ; et
al. |
September 9, 2021 |
Methods for Reactive Three-Dimensional Printing by Extrusion
Abstract
Methods of printing a three-dimensional object using co-reactive
components are disclosed. Thermosetting compositions for
three-dimensional printing are also enclosed.
Inventors: |
Fenn; David R.; (Allison
Park, PA) ; Olson; Kurt G.; (Gibsonia, PA) ;
Rock; Reza M.; (Pittsburgh, PA) ; Kutchko;
Cynthia; (Pittsburgh, PA) ; Donaldson; Susan F.;
(Allison Park, PA) ; Sun; Hao; (Allison Park,
PA) ; Rios; Orlando; (Knoxville, TN) ; Carter;
William G.; (Oak Ridge, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PPG Industries Ohio, Inc.
UT-Battelle, LLC |
Cleveland
Oak Ridge |
OH
TN |
US
US |
|
|
Family ID: |
1000005599487 |
Appl. No.: |
17/201731 |
Filed: |
March 15, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15528443 |
May 19, 2017 |
10982105 |
|
|
PCT/US2015/062445 |
Nov 24, 2015 |
|
|
|
17201731 |
|
|
|
|
62158588 |
May 8, 2015 |
|
|
|
62083472 |
Nov 24, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 64/112 20170801;
C08G 18/7893 20130101; C09D 175/02 20130101; C08G 18/4854 20130101;
C09D 11/38 20130101; C08G 2150/50 20130101; B33Y 80/00 20141201;
B29K 2075/02 20130101; C08G 18/325 20130101; C09D 11/102 20130101;
C08G 18/3225 20130101; C08G 18/3821 20130101; C09D 11/03 20130101;
C08G 18/73 20130101; B33Y 10/00 20141201; C09D 11/30 20130101; C08G
18/792 20130101; C08G 18/755 20130101; C08G 18/5024 20130101; C08G
18/10 20130101; B33Y 70/00 20141201; C08K 3/36 20130101; C08G
18/3228 20130101; C08G 18/3234 20130101 |
International
Class: |
C09D 11/102 20060101
C09D011/102; C08G 18/48 20060101 C08G018/48; C08G 18/50 20060101
C08G018/50; C08G 18/75 20060101 C08G018/75; C08G 18/79 20060101
C08G018/79; C08K 3/36 20060101 C08K003/36; C09D 175/02 20060101
C09D175/02; C08G 18/32 20060101 C08G018/32; C08G 18/38 20060101
C08G018/38; B33Y 70/00 20060101 B33Y070/00; B29C 64/112 20060101
B29C064/112; B33Y 80/00 20060101 B33Y080/00; C08G 18/10 20060101
C08G018/10; C08G 18/73 20060101 C08G018/73; C09D 11/03 20060101
C09D011/03; C09D 11/30 20060101 C09D011/30; C09D 11/38 20060101
C09D011/38; B33Y 10/00 20060101 B33Y010/00; C08G 18/78 20060101
C08G018/78 |
Goverment Interests
[0002] This invention was made with government support under
Contract Number DE-AC05-00OR22725 awarded by the U.S. Department of
Energy and under Cooperative Research and Development Agreement
NFE-14-05242. The government has certain rights in the
invention.
NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] UT-Battelle, LLC, One Bethel Valley Road, Building 4500N,
MS-6258, Oak Ridge, Tenn. 37831-6258 and PPG Industries Ohio, Inc.,
3800 West 143.sup.rd Street, Cleveland, Ohio 44111.
Claims
1.-26. (canceled)
27. A method of three-dimensional printing an object comprising:
(a) extruding a coreactive composition, wherein, the coreactive
composition comprises a first component comprising at least two
first functional groups and a second component comprising at least
two second functional groups, the second functional group is
reactive with the first functional group; and at least one of the
first functional group and the second functional group comprises a
saturated functional group; and (b) building a three-dimensional
printed object; wherein extruding comprises forming an extrusion
wherein the extrusion is characterized by a cross-sectional profile
having an inhomogeneous material composition.
28. The method of claim 27, wherein, the cross-sectional profile
comprises a first proton and a second portion; the first portion
comprises a molar ratio of the first component to the second
component greater than 1; and the second portion comprises a molar
ratio of the first component to the second component less than
1.
29. The method of claim 28, wherein the first portion and the
second portion are on opposite sides of the cross-sectional
profile.
30. The method of claim 28, wherein, the first portion comprises an
equivalent ratio of the first functional group to the second
functional group greater than 1; and the second portion comprises
an equivalent ratio of the first functional group to the second
functional group less than 1.
31. The method of claim 27, wherein an equivalents ratio of the
first component to the second component is not homogeneous
throughout the cross-sectional profile.
32. The method of claim 27, wherein an equivalents ratio of the
first component to the second component is homogeneous throughout
the cross-sectional profile.
33. The method of claim 27, wherein a surface of the extrudate has
an excess of the first functional groups with respect to the second
functional groups.
34. The method of claim 27, wherein the cross-sectional profile is
characterized by a variable ratio of the first coreactive component
and the second coreactive component.
35. The method of claim 27, wherein, the first functional group is
a carboxylic acid; and the second functional group is an epoxy; or
the first functional group is an activated unsaturated group
selected from a (meth)acrylate, a maleic acid, a fumaric acid, a
Michael acceptor, a vinyl ether, an acetoacetate, an acyclic
carbonate, and a malonate; and the second functional group is
selected from a primary amine, a secondary amine, and a malonate;
or the first functional group is an isocyanate; and the second
functional group is a hydroxyl; or the first functional group is an
isocyanate; and the second functional group is selected from a
primary amine and a secondary amine; or the first functional group
is selected from a cyclic carbonate, an acetoacetate, and an epoxy;
and the second functional group is selected from a primary amine
and a secondary amine; or the first functional group is a thiol;
and the second functional group is selected from an alkenyl, a
vinyl ether, a Michael acceptor group and a (meth)acrylate; or at
least one of the first functional group and the second functional
group comprises a saturated functional group.
36. The method of claim 27, wherein the first component comprises a
polyisocyanate and the second component comprises a polyamine.
37. The method of claim 27, wherein the first component comprises a
polythiol; and the second component comprises a polyalkenyl.
38. The method of claim 27, wherein the first component comprises a
polyfunctional Michael acceptor and the second component comprises
a polyfunctional Michael donor.
39. The method of claim 27, wherein extruding comprises extruding
the coreactive composition through a single nozzle.
40. The method of claim 27, wherein the coreactive composition is a
thermosetting composition.
41. The method of claim 27, wherein the coreactive composition is
reactive at a temperature less than 30.degree. C.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 15/528,443, filed on May 19, 2017, now allowed, which is a
national stage entry under 35 U.S.C. .sctn. 371 of International
Application No. of PCT/US2015/062445, filed on Nov. 24, 2015, which
claims the benefit under 35 U.S.C. .sctn. 119(e) of U.S.
Provisional Application No. 62/158,588, filed on May 8, 2015, and
U.S. Provisional Application No. 62/083,472 filed on Nov. 24, 2014,
each of which is incorporated by reference in its entirety.
FIELD
[0004] The present invention relates to three-dimensional printing
methods and coreactive printing compositions, more particularly to
the use of three-dimensional printing compositions comprising
coreactive components.
BACKGROUND
[0005] In three-dimensional (3D) printing, a composition is laid
down in successive layers of material to build a structure from a
series of cross-sections of the structure. These layers may be
produced, for example, from liquid, powder, paper, or sheet
material.
[0006] In certain cases, a 3D printing composition is a
thermoplastic material, which is extruded through a heated nozzle
on to a platform and the nozzle moved with respect to the platform,
successively building up layers of thermoplastic material to form a
3D object. After being extruded from the nozzle, the thermoplastic
material rapidly cools. Depending in part on the temperature of the
underlying thermoplastic layer, the overlying thermoplastic layer
may or may not adhere well to the underlying thermoplastic layer.
Furthermore, differential thermal expansion can cause stress to be
built up in the finished object thereby diminishing the integrity
of the object.
SUMMARY
[0007] Embodiments of the present disclosure include methods of
three-dimensional printing of an object by forming an object using
a coreactive printing composition, such as polyurea composition,
that is produced from a mixture of at least two coreactive
components having coreactive functional groups wherein at least one
of the coreactive components comprises a saturated functional
group. Also included within the scope of the present disclosure is
printed three-dimensional objects formed from layers of a
coreactive printing composition, such as a polyurea composition,
produced from at least two coreactive components.
[0008] According to the present invention, compositions for
three-dimensional printing comprise: a first component comprising a
first functional group; and a second component comprising a second
functional group, wherein the second functional group is reactive
with the first functional group; and wherein at least one of the
first functional group and the second functional group comprises a
saturated functional group.
[0009] According to the present invention, compositions for
three-dimensional printing comprise: a first component comprising a
first functional group; and a second component comprising a second
functional group, wherein, the first component comprises a
polyamine and the second component comprises a polyisocyanate; the
first component comprises a polyalkenyl compound and the second
component comprises a polythiol; the first component comprises a
Michael addition acceptor and the second component comprises a
Michael addition donor; or a combination of any of the foregoing;
wherein the composition is characterized by a shear storage modulus
G' and a shear loss modulus G'', wherein, the initial G''/G' ratio
is less than 2; the initial G' is greater than 1,500 Pa; the G' at
6 minutes is greater than 500,000 Pa; and the G'' at 6 minutes
after mixing is greater than 400,000 Pa; wherein, the shear storage
modulus G' and the shear loss modulus G'' are measured using a
rheometer with a gap from 1 mm to 2 mm, with a 25 mm-diameter
parallel plate spindle, an oscillation frequency of 1 Hz and
amplitude of 0.3%, and with a rheometer plate temperature of
25.degree. C.
[0010] According to the present invention, compositions comprise: a
first component comprising a first functional group; and a second
component comprising a second functional group, wherein, the first
component comprises a polyamine and the second component comprises
a polyisocyanate; the first component comprises a polyalkenyl
compound and the second component comprises a polythiol; the first
component comprises a Michael addition acceptor and the second
component comprises a Michael addition donor; or a combination of
any of the foregoing; wherein the composition is characterized by:
a viscosity less than 30 cP; a surface tension of 30 mN/m to 50
nM/m; a contact angle on glass of less than 20 degrees; and a
contact angle on polyethylene terephthalate of less than 40
degrees.
[0011] According to the present invention, three-dimensional object
can be formed using a composition provided by the present
disclosure.
[0012] According to the present invention, methods of
three-dimensional printing an object comprise: extruding a first
component comprising a first functional group and a second
component comprising a second functional group, wherein, the second
functional group is reactive with the first functional group; and
at least one of the first functional group and the second
functional group comprises a saturated functional group; and
building a three-dimensional printed object.
[0013] According to the present invention, methods of
three-dimensional printing an object comprise: depositing by inkjet
printing a first reactive component comprising a first functional
group; depositing by inkjet printing a second component comprising
a second functional group; wherein, the second functional group is
reactive with the first functional group; and at least one of the
first functional group and the second functional group comprises a
saturated functional group; and building a three-dimensional
printed object.
[0014] According to the present invention, three-dimensional
objects can be formed using a method provided by the present
disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The drawings described herein are for illustration purposes
only. The drawings are not intended to limit the scope of the
present disclosure.
[0016] FIG. 1 is a graph showing the dynamic modulus (G' vs. G'')
of polyurea compositions that did not satisfy desired build
criteria.
[0017] FIG. 2 is a graph showing the dynamic modulus (G' vs. G'')
of polyurea compositions that met desired build criteria.
DESCRIPTION
[0018] For purposes of the following detailed description, it is to
be understood that the invention may assume various alternative
variations and step sequences, except where expressly specified to
the contrary. Moreover, other than in any operating examples or
where otherwise indicated, all numbers expressing, for example,
quantities of ingredients used in the specification and 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 to be obtained by 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 claims, each numerical
parameter should at least be construed in light of the number of
reported significant digits and by applying ordinary rounding
techniques. Notwithstanding that the numerical ranges and
parameters setting forth the broad scope of the invention are
approximations, the numerical values set forth in the specific
examples are reported as precisely as possible. Any numerical
value, however, inherently contains certain errors necessarily
resulting from the standard variation found in their respective
testing measurements.
[0019] Also, it should be understood that any numerical range
recited herein is intended to include all sub-ranges subsumed
therein. For example, a range of "1 to 10" is intended to include
all sub-ranges between (and including) the recited minimum value of
1 and the recited maximum value of 10, that is, having a minimum
value equal to or greater than 1 and a maximum value of equal to or
less than 10.
[0020] The use of the singular includes the plural and plural
encompasses singular, unless specifically stated otherwise. In
addition, the use of "or" means "and/or" unless specifically stated
otherwise, even though "and/or" may be explicitly used in certain
instances.
[0021] The term "polymer" is meant to include prepolymer,
homopolymer, copolymer, and oligomer.
[0022] Embodiments of the present disclosure are directed to the
production of structural objects using three-dimensional printing.
A three-dimensional object may be produced by forming successive
portions or layers of an object by depositing at least two
coreactive components onto a substrate and thereafter depositing
additional portions or layers of the object over the underlying
deposited portion or layer. Layers are successively deposited to
build the 3D printed object. The coreactive components can be mixed
and then deposited or can be deposited separately. When deposited
separately, the components can be deposited simultaneously,
sequentially, or both simultaneously and sequentially.
[0023] Deposition and similar terms refer to the application of a
printing material comprising a thermosetting or coreactive
composition and/or its reactive components onto a substrate (for a
first portion of the object) or onto previously deposited portions
or layers of the object. Each coreactive component may include
monomers, prepolymers, adducts, polymers, and/or crosslinking
agents, which can chemically react with the constituents of the
other coreactive component.
[0024] By "portions of an object" is meant subunits of an object,
such as layers of an object. The layers may be on successive
horizontal parallel planes. The portions may be parallel planes of
the deposited material or beads of the deposited material produced
as discreet droplets or as a continuous stream of material. The at
least two coreactive components may each be provided neat or may
also include a solvent (organic and/or water) and/or other
additives as described below. Coreactive components provided by the
present disclosure may be substantially free of solvent. By
substantially free is meant less than about 5 wt %, less than about
4 wt %, less than about 2 wt %, or less than 1 wt % of solvent,
where wt % is based on the total weight of a composition.
[0025] The at least two coreactive components may be mixed together
and subsequently deposited as a mixture of coreactive components
that react to form portions of the object. For example, the two
coreactive components may be mixed together and deposited as a
mixture of coreactive components that react to form the
thermosetting composition by delivery of at least two separate
streams of the coreactive components into a mixer such as a static
mixer to produce a single stream that is then deposited. The
coreactive components may be at least partially reacted by the time
a composition comprising the reaction mixture is deposited. The
deposited reaction mixture may react at least in part after
deposition and may also react with previously deposited portions
and/or subsequently deposited portions of the object such as
underlying layers or overlying layers of the object.
[0026] Alternatively, the two coreactive components may be
deposited separately from each other to react upon deposition to
form the portions of the object. For example, the two coreactive
components may be deposited separately such as by using an inkjet
printing system whereby the coreactive components are deposited
overlying each other and/or adjacent to each other in sufficient
proximity so the two reactive components may react to form the
portions of the object. As another example, in an extrusion, rather
than being homogeneous, a cross-sectional profile of the extrusion
may be inhomogeneous such that different portions of the
cross-sectional profile may have one of the two coreactive
components and/or may contain a mixture of the two coreactive
components in a different molar and/or equivalents ratio.
[0027] Furthermore, throughout a 3D-printed object, different parts
of the object may be formed using different proportions of the two
coreactive components such that different parts of an object may be
characterized by different material properties. For example, some
parts of an object may be rigid and other parts of an object may be
flexible.
[0028] It will be appreciated that the viscosity, reaction rate,
and other properties of the coreactive components may be adjusted
to control the flow of the coreactive components and/or the
thermosetting compositions such that the deposited portions and/or
the object achieves and retains a desired structural integrity
following deposition. The viscosity of the coreactive components
may be adjusted by the inclusion of a solvent, or the coreactive
components may be substantially free of a solvent or completely
free of a solvent. The viscosity of the coreactive components may
be adjusted by the inclusion of a filler, or the coreactive
components may be substantially free of a filler or completely free
of a filler. The viscosity of the coreactive components may be
adjusted by using components having lower or higher molecular
weight. For example, a coreactive component may comprise a
prepolymer, a monomer, or a combination of a prepolymer and a
monomer. The viscosity of the coreactive components may be adjusted
by changing the deposition temperature. The coreactive components
may have a viscosity and temperature profile that may be adjusted
for the particular deposition method used, such as mixing prior to
deposition and/or ink-jetting. The viscosity may be affected by the
composition of the coreactive components themselves and/or may be
controlled by the inclusion of rheology modifiers as described
herein.
[0029] It can be desirable that the viscosity and/or the reaction
rate be such that following deposition of the coreactive components
the composition retains an intended shape. For example, if the
viscosity is too low and/or the reaction rate is too slow a
deposited composition may flow in a way the compromises the desired
shape of the finished object. Similarly, if the viscosity is too
high and/or the reaction rate is too fast, the desired shape may be
compromised.
[0030] For example, the coreactive components that are deposited
together may each have a viscosity at 25.degree. C. and a shear
rate at 0.1 s.sup.-1 from 5,000 centipoise (cP) to 5,000,000 cP,
from 50,000 cP to 4,000,000 cP, or from 200,000 cP to 2,000,000 cP.
The coreactive components that are deposited together may each have
a viscosity at 25.degree. C. and a shear rate at 1,000 s.sup.-1
from 50 centipoise (cP) to 50,000 cP, from 100 cP to 20,000 cP, or
from 200 to 10,000 cP. Viscosity values can be measured using an
Anton Paar MCR 301 or 302 rheometer with a gap from 1 mm to 2
mm.
[0031] Coreactive components that are ink jetted or otherwise
deposited separately from each other (not mixed before deposition)
may have a viscosity at 25.degree. C. of at least 1 cP, at least 5
cP, or at least 10 cP. The separately deposited coreactive
components may have a viscosity at 25.degree. C. that is no more
than 20 cP, no more than 30 cP, no more than 40 cP, no more than 50
cP, no more than 75 cP, no more than 100 cP, or no more than 120
cP.
[0032] The rate of interlayer crosslinking between successive and
adjacent layers of a deposited object can be controlled to
facilitate interlayer reaction and thereby improve the interlayer
strength. The rate of interlayer crosslinking can be controlled,
for example, by adjusting the time between deposition of successive
layers, adjusting the temperature, adjusting the concentration of a
catalyst, and/or adjusting the components of the composition such
as the amount of monomer and prepolymer. A deposited layer may be
homogeneous or a deposited layer may be inhomogeneous. For an
inhomogeneous layer, a cross-section of the layer may have
different chemical compositions. For example to improve interlayer
adhesion, a part of a layer may have an excess of a certain
coreactive functionality that can then react with an excess of a
coreactive functionality of an overlying layer. Similarly, to
improve interlayer adhesion, a lower part of a layer may have an
excess of a certain coreactive functionality that can then react
with an excess of a coreactive functionality of an underlying
layer. To improve interlayer adhesion, a tie coating, film, or
layer may be applied or deposited over a deposited layer prior to
or during deposition of an overlying layer.
[0033] The coreactive components may include a first component
having at least two functional groups per molecule (referred to as
the "A" functional groups) and a second component having at least
two functional groups per molecule (referred to as the "B"
functional groups), where the A functional groups and the B
functional groups are coreactive with each other, are different
from each other, and at least one of the two coreactive components
includes a saturated functional group.
[0034] A "saturated functional group" refers to a functional group
of component coreactive component that does not include an
unsaturated reactive group, although there may be unsaturation in
other (non-reactive) portions of the compound of the coreactive
component. An example of a saturated group includes thiol groups
and an example of an unsaturated group includes alkenyl and
acrylate groups. Examples of saturated functional groups include
thiol, hydroxyl, primary amine, secondary amine, and epoxy groups.
In certain compositions, a saturated functional group can be a
thiol, a primary amine, a secondary amine, or a combination of any
of the foregoing. In certain compositions, a saturated functional
group can be a thiol, a primary amine, a secondary amine, an epoxy,
or a combination of any of the foregoing. Examples of unsaturated
functional groups include alkenyl groups, activated unsaturated
groups such as acrylate, maleic, or fumaric acid groups, isocyanate
groups, acyclic carbonate groups, acetoacetate groups, carboxylic
acid groups, Michael acceptor groups, vinyl ether groups,
(meth)acrylate groups, and malonate groups.
[0035] Compositions provided by the present disclosure can comprise
a first component comprising a first functional group, and a second
component comprising a second functional group, wherein the second
functional group is reactive with the first functional group, and
both of the functional groups do not comprise ethylenically
unsaturated groups. Examples of ethylenically unsaturated groups
include (meth)acrylate groups, Michael acceptor groups, and vinyl
ether groups.
[0036] In certain compositions provided by the present disclosure
the first component and the second component do not include a
polyisocyanate and a polyol.
[0037] B functional groups may be capable of reacting with the A
functional groups at moderate temperature such as less than
140.degree. C., less than 100.degree. C., less than 60.degree. C.,
less than 50.degree. C., less than 40.degree. C., less than
30.degree. C., or less than 25.degree. C. The A and B functional
groups may react together at room temperature such as 20.degree. C.
One or both of the coreactive components may have on average more
than two reactive groups per molecule, in which case the mixture of
coreactive components comprises a thermosetting composition.
Suitable coreactive functional groups are described, for example,
in Noomen, Proceedings of the XIIIth International Conference in
Organic Coatings Science and Technology, Athens, 1987, page 251;
and in Tillet et al., Progress in Polymer Science 36 (2011),
191-217, which is incorporated by reference in its entirety. The
reaction between the A groups and the B groups may not involve the
elimination of a by-product. Such reactions are often referred to
as addition reactions. Examples of suitable coreactive functional
groups A and B are listed in Table 1.
TABLE-US-00001 TABLE 1 Functional Groups. Functional Groups A
Functional Groups B Carboxylic acid Epoxy Activated unsaturated
groups such Primary or secondary amine as acrylate, maleic or
fumaric Isocyanate Primary or secondary amine Isocyanate Hydroxyl
Cyclic carbonate Primary or secondary amine Acetoacetate Primary or
secondary amine Epoxy Primary or secondary amine Thiol Alkenyl
Thiol Vinyl ether Thiol (Meth)acrylate Activated unsaturated groups
such Malonate as acrylate or maleic
[0038] A first coreactive component may include compounds having
more than one type of functional group A, and the second coreactive
component may include components having more than one type of
functional group B, such that a 3D-printing material can comprise
at least two sets of coreactive A and B groups, wherein at least
one coreactive component has a functional group that is saturated.
For example, a first coreactive component may have hydroxyl groups
and secondary amine groups (i.e. at least two different functional
groups) and the second coreactive component may have isocyanate
groups. One or both of the coreactive components may optionally
comprise a catalyst for the reaction between the A groups and the B
groups. The A groups and the B groups may be attached to any
suitable compound such as a monomer and/or a prepolymer.
Optionally, the A groups and the B groups may be attached to an
oligomer, polymer, or prepolymer such as polyester, polyurethane,
or acrylic oligomer, polymer, or prepolymer. In general, monomers
refer to compounds without repeating units in the backbone, and can
be characterized, for example, by a molecular weight less than 600
Daltons, less than 500 Daltons, or less than 400 Daltons. In
general, a prepolymer refers to a compound having repeat units in
backbone and can be characterized, for example, by a molecular
weight from 1,000 Daltons to 20,000 Daltons, from 1,000 Daltons to
10,000 Daltons, or from 2,000 Daltons to 5,000 Daltons.
[0039] The functional groups A and B may be terminal groups and/or
pendent groups. A coreactive component can have a functionality of
two or a functionality greater than two, such as a functionality
from 2 to 6. Each functional group of a coreactive component can be
the same or certain functional groups of a coreactive component can
be different. For example, a coreactive component can have more
than one different type of functional group reactive with an
isocyanate, such as a primary amine group, a secondary amine group,
or a hydroxyl group.
[0040] In a composition comprising at least two coreactive
component, the first component can comprise a polyamine and the
second component can comprise a polyisocyanate; the first component
can comprise a polyalkenyl compound and the second component can
comprise a polythiol; a the first component can comprise a Michael
addition acceptor and the second component can comprise a Michael
addition donor; or a combination of any of the foregoing; In a
composition comprising at least two coreactive components, the
first component can comprise an isocyanate-functional prepolymer;
and the second functional group can comprise a primary amine, a
secondary amine, a hydroxyl, or a combination of any of the
foregoing.
[0041] A composition for three-dimensional printing can comprise a
first component comprising a first functional group, and a second
component comprising a second functional group, wherein the first
and second functional groups are reactive with each other, and at
least one of the first functional group and the second functional
group comprise a saturated functional group. One of the first and
second functional groups may be an unsaturated functional group, or
both the first and second functional groups may be a saturated
functional group. Both the first functional group and the second
functional groups are not unsaturated functional groups. A
composition provided by the present disclosure may contain
additional coreactive components, which may comprise saturated
and/or unsaturated functional groups.
[0042] The coreactive functional groups can react to form covalent
bonds. The reaction between the coreactive functional groups can be
catalyzed by a catalyst. In certain compositions, the reaction
between the coreactive functional groups does not involve a
free-radical initiated reaction. Compositions provided by the
present disclosure may be thermoset compositions.
[0043] Compositions provided by the present disclosure may include
two coreactive components or more than two coreactive components. A
reactive component can comprise a combination of reactive
components having the same functional group, such as a combination
of monomers and prepolymers having the same functional group. An
additional coreactive component can comprise a compound having a
different functional group reactive with a first functional group
or the second functional group. An additional coreactive component
can impart an additional property to the composition. For example,
the reaction rate of the additional coreactive component with one
of the other coreactive components may be rapid and thereby
facilitate the ability of a deposited layer to maintain a desired
shape before the other components fully cure.
[0044] The first component and the second component can be combined
in a suitable ratio to form a curable composition. For example, the
functional Group A to functional Group B equivalent ratio of a
curable composition can be from 1:1 to 1.5:1, from 1:1 to 1.45:1,
from 1: to 3:1, from 1.2:1 to 1.5:1, or from 1.2:1 to 1.4:1. A
suitable functional Group A to functional Group B equivalent ratio
of a curable composition can be, for example, from 2:1 to 1:2, from
1.5:1 to 1:1.5, or from 1.1:1 to 1:1.1.
[0045] Compositions provided by the present disclosure can include
one or both of the coreactive components such that the ratio of
coreactive components in one portion of the object differs from the
ratio of coreactive components in another part of the object. In
this manner, portions of an object may have differing final
compositions. The different compositions may differ by the weight
percent of the coreactive compositions, the equivalent ratio of
reactive monomers or reactants within the coreactive compositions,
the type and/or level of filler, the crosslinking density, and/or
properties such as glass transition temperature. Accordingly, one
portion of an object produced in the three-dimensional printing may
have different material properties such as different chemical,
physical, thermal, or material properties than those of another
portion of the three-dimensional object.
[0046] In addition, one portion of an object may partially react
with at least some other coreactive components in an adjacent
portion of the object. Such reaction may occur during deposition
and/or after the coreactive components are deposited in each
adjacent portion, whereby the coreactive components react in part
within each adjacent portion and the coreactive components between
adjacent portions react. In this manner, the deposited portions of
an object may be covalently bound together as the coreactive
compositions react between the portions of the object, thereby
increasing the physical and structural integrity of the
three-dimensional object. For example, unreacted isocyanate and/or
amine groups present on the surface of an underlying deposited
layer, can react with unreacted groups of a subsequently deposited
layer. This increases the strength/integrity of the object by
providing reaction between layers of deposited material, in
addition to reaction within the same layer.
[0047] A printed three-dimensional object can include layers formed
from a thermosetting or coreactive composition, such as a polyurea
composition, that is produced from at least two printed coreactive
components and which may be crosslinked. In the case of polyurea,
one of the coreactive components may include an
isocyanate-functional prepolymer or oligomer and another coreactive
component may include an amine such as a primary or secondary
amine. The isocyanate-functional coreactive components may further
include isocyanate-functional monomers. The amine containing
coreactive component may further include another reactant with
functional groups reactive with the isocyanate-functional
prepolymer, oligomer, and/or monomer such as hydroxyl groups.
Adjacent portions of a printed three-dimensional object may be
reacted with some of the coreactive compositions in one or more
adjacent portions.
[0048] For a polyurea composition, the coreactive components may
include an isocyanate-functional component that may include
polyisocyanate monomers, prepolymers, oligomers, adducts, polymers,
or a blend of polyisocyanates. A prepolymer can be a polyisocyanate
which is pre-reacted with a sufficient amount of polyamine(s) or
other isocyanate-reactive components such as one or more polyols,
so that reactive isocyanate sites on the polyisocyanate remain in
the isocyanate-functional prepolymer.
[0049] Suitable monomeric polyisocyanates include, for example,
isophorone diisocyanate (IPDI), which is
3,3,5-trimethyl-5-isocyanato-methyl-cyclohexylisocyanate;
hydrogenated diisocyanates such as cyclohexylene diisocyanate,
4,4'-methylenedicyclohexyl diisocyanate (H.sub.12MDI); mixed
aralkyl diisocyanates such as tetramethylxylyl diisocyanates,
OCN--C(--CH.sub.3).sub.2--C.sub.6H.sub.4C(CH.sub.3).sub.2--NCO; and
polymethylene isocyanates such as 1,4-tetramethylene diisocyanate,
1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate
(HMDI), 1,7-heptamethylene diisocyanate, 2,2,4- and
2,4,4-trimethylhexamethylene diisocyanate, 1,10-decamethylene
diisocyanate and 2-methyl-1,5-pentamethylene diisocyanate.
[0050] Aliphatic isocyanates are particularly useful in producing
three-dimensional polyurea objects that are resistant to
degradation by UV light. However, in other circumstances, less
costly aromatic polyisocyanates may be used when durability is not
of significant concern. Examples of monomeric aromatic
polyisocyanates include phenylene diisocyanate, toluene
diisocyanate (TDI), xylene diisocyanate, 1,5-naphthalene
diisocyanate, chlorophenylene 2,4-diisocyanate, bitoluene
diisocyanate, dianisidine diisocyanate, tolidine diisocyanate and
alkylated benzene diisocyanates generally; methylene-interrupted
aromatic diisocyanates such as methylenediphenyl diisocyanate,
especially the 4,4'-isomer (MDI) including alkylated analogs such
as 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate and polymeric
methylenediphenyl diisocyanate.
[0051] Suitable polyisocyanates also include polyisocyanates
prepared from dimers and trimers of diisocyanate monomers. Dimers
and trimers of diisocyanate monomers can be prepared, for example,
by methods described in U.S. Pat. No. 5,777,061 at column 3, line
44 through column 4, line 40, which is incorporated by reference in
its entirety. Dimers and trimers of diisocyanate monomers may
contain linkages selected from isocyanurate, uretdione, biuret,
allophanate and combinations thereof, such as Desmodur.RTM. N3600,
Desmodur.RTM. CP2410, and Desmodur.RTM. N3400, available from Bayer
Material Science.
[0052] A polyisocyanate can also comprise a polyisocyanate
prepolymer. For example, a polyisocyanate can include an
isocyanate-terminated polyether diol, an extended polyether diol,
or a combination thereof. An extended polyether diol refers to a
polyether diol that has been reacted with an excess of a
diisocyanate resulting in an isocyanate-terminated polyether
prepolymer with increased molecular weight and urethane linkages in
the backbone. Examples of polyether diols include Terathane.RTM.
polyether diols such as Terathane.RTM. 200 and Terathane.RTM. 650
available from Invista or the PolyTHF.RTM. polyether diols
available from BASF. Isocyanate-terminated polyether prepolymers
can be prepared by reacting a diisocyanate and a polyether diol as
described in U.S. Application Publication No. 2013/0344340, which
is incorporated by reference in its entirety. The number average
molecular weight of an extended isocyanate-terminated prepolymer
can be, for example, from 250 Daltons to 10,000 Daltons, or from
500 Daltons to 7,500 Daltons.
[0053] A polyisocyanate can include a difunctional isocyanate, a
trifunctional isocyanate, a difunctional isocyanate-terminated
prepolymer, an extended difunctional isocyanate-terminated
prepolymer, or a combination of any of the foregoing.
[0054] The amine-functional coreactive component used to produce a
three-dimensional polyurea object may include primary and/or
secondary amines or mixtures thereof. The amines may be monoamines,
or polyamines such as diamines, triamines, higher polyamines and/or
mixtures thereof. The amines also may be aromatic or aliphatic such
as cycloaliphatics. Examples of suitable aliphatic polyamines
include, ethylene diamine, 1,2-diaminopropane, 1,4-diaminobutane,
1,3-diaminopentane, 1,6-diaminohexane, 2-methyl-1,5-pentane
diamine, 2,5-diamino-2,5-dimethylhexane, 2,2,4- and/or
2,4,4-trimethyl-1,6-diamino-hexane, 1,11-diaminoundecane,
1,12-diaminododecane, 1,3- and/or 1,4-cyclohexane diamine,
1-amino-3,3,5-trimethyl-5-aminomethyl-cyclohexane, 2,4- and/or
2,6-hexahydrotolulene diamine, 2,4'- and/or 4,4'-di
amino-dicyclohexyl methane,
5-amino-1,3,3-trimethylcyclohexanemethylamine (isophoronediamine),
1,3-cyclohexanebis(methylamine) (1,3 BAC), and
3,3'-dialkyl-4,4'-diaminodicyclohexyl methanes (such as
3,3'-dimethyl-4,4'-diaminodicyclohexyl methane and
3,3'-diethyl-4,4'-diaminodicyclohexyl methane), 2,4- and/or
2,6-diaminotoluene and 2,4'- and/or 4,4'-diaminodiphenyl methane,
or mixtures thereof.
[0055] Suitable secondary amines include acrylates and
methacrylate-modified amines. By "acrylate and methacrylate
modified amines" includes both mono- and poly-acrylate modified
amines as well as acrylate or methacrylate modified mono- or
poly-amines. Acrylate or methacrylate modified amines can include
aliphatic amines.
[0056] A secondary amine may include an aliphatic amine, such as a
cycloaliphatic diamine. Such amines are available commercially from
Huntsman Corporation (Houston, Tex.) under the designation of
JEFFLINK.TM. such as JEFFLINK.TM. 754. The amine may be provided as
an amine-functional resin. Such amine-functional resins may be a
relatively low viscosity, amine-functional resins suitable for use
in the formulation of high solids polyurea three-dimensional
objects. An amine-functional resin may comprise an ester of an
organic acid, for example, an aspartic ester-based amine-functional
reactive resin that is compatible with isocyanates; e.g., one that
is solvent-free. An example of such polyaspartic esters is the
derivative of diethyl maleate and 1,5-diamino-2-methylpentane,
available commercially from Bayer Corporation. PA under the trade
name DESMOPHEN.TM. NH1220. Other suitable compounds containing
aspartate groups may be employed as well.
[0057] An amine-functional coreactive component also may include
high molecular weight primary amines, such as
polyoxyalkyleneamines. Polyoxyalkyleneamines contain two or more
primary amino groups attached to a backbone, derived, for example,
from propylene oxide, ethylene oxide, or a mixture thereof.
Examples of such amines include those available under the
designation JEFFAMINE.TM. from Huntsman Corporation. Such amines
can have a molecular weight from 200 Daltons to 7,500 Daltons, such
as, for example, JEFFAMINE.TM. D-230, D-400, D-2000, T-403 and
T-5000.
[0058] An amine-functional co-reactive component may also include
an aliphatic secondary amine such as Clearlink.RTM. 1000, available
from Dor-Ketal Chemicals, LLC.
[0059] An amine-functional coreactive component can comprise an
amine-functional aspartic acid ester, a polyoxyalkylene primary
amine, an aliphatic secondary amine, or a combination of any of the
foregoing.
[0060] For a polyurea formed from coreactive components comprising
an isocyanate and a (meth)acrylate amine reaction product of a
monoamine and poly(meth)acrylate, the term "(meth)acrylate" denotes
both the acrylate and the corresponding (meth)acrylate. The
poly(meth)acrylate may be any suitable poly(meth)acrylate and
mixtures thereof. A poly(meth)acrylate can include a
di(meth)acrylate, a poly(meth)acrylate can comprise
tri(meth)acrylate, or a poly(meth) acrylate can include
tetra(meth)acrylate. Suitable di(meth)acrylates include, for
example, ethylene glycol, di(meth)acrylate, 1,3-butylene glycol
di(meth)acrylate, 1,4-butanediol di(meth)acrylate,
2,3-dimethylpropane 1,3-di(meth)acrylate, 1,6-hexanediol
di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene
glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate,
tetraethylene glycol di(meth)acrylate, tetrapropylene glycol
di(meth)acrylate, ethoxylated hexanediol di(meth)acrylate,
propoxylated hexanediol di(meth)acrylate, neopentyl glycol
di(meth)acrylate, alkoxylated neopentyl glycol di(meth)acrylate,
hexylene glycol di(meth)acrylate, diethylene glycol
di(meth)acrylate, polyethylene glycol di(meth)acrylate,
polybutadiene di(meth)acrylate, thiodiethyleneglycol
di(meth)acrylate, trimethylene glycol di(meth)acrylate, triethylene
glycol di(meth)acrylate, alkoxylated hexanediol di(meth)acrylate,
alkoxyolated neopentyl glycol di(meth)acrylate, pentanediol
di(meth)acrylate, cyclohexane dimethanol di(meth)acrylate,
ethoxylated bis-phenol A di(meth)acrylate, and mixtures of any of
the foregoing. Examples of tri and higher (meth)acrylates include
glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate,
ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated
trimethylolpropane tri(meth)acrylate, ditrimethylolpropane
tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate,
ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated
pentaerythritol tetra(meth)acrylate, and dipentaerythritol
penta(meth)acrylate. Other suitable poly(meth)acrylate oligomers
include (meth)acrylate of epoxidized soya oil and urethane
acrylates of polyisocyanates and hydroxyalkyl (meth)acrylates.
Mixtures of poly(meth)acrylate monomers may also be used, including
mixtures of mono, di, tri, and/or tetra (meth)acrylate.
[0061] Other suitable poly(meth)acrylates include urethane
(meth)acrylates such as those formed from the reaction of
hydroxy-functional (meth)acrylate with a polyisocyanate or with an
isocyanate-functional adduct of a polyisocyanate and a polyol or a
polyamine. Suitable hydroxy-functional (meth)acrylates include
2-hydroxyethyl, 1-methyl-2-hydroxyethyl, 2-hydroxypropyl,
2-hydroxybutyl, 4-hydroxybutyl, and the like. Suitable
polyisocyanates include, for example, any of the monomeric or
oligomeric isocyanates, or isocyanate prepolymers disclosed
herein.
[0062] A thermosetting or coreactive composition provided by the
present disclosure can be based on thiol-ene chemistry. For
example, a thermosetting composition provided by the present
invention having thiol-ene functionality may include a polyene
coreactive component comprising compounds or prepolymers having
terminal and/or pendent olefinic double bonds, such as terminal
alkenyl groups. Examples of such compounds include
(meth)acrylic-functional (meth)acrylic copolymers, epoxy acrylates
such as epoxy resin (meth)acrylates (such as the reaction product
of bisphenol A diglycidyl ether and acrylic acid), polyester
(meth)acrylates, polyether (meth)acrylates, polyurethane
(meth)acrylates, amino (meth)acrylates, silicone (meth)acrylates,
and melamine (meth)acrylates.
[0063] Examples of suitable polyurethane (meth)acrylates include
reaction products of polyisocyanates such as 1,6-hexamethylene
diisocyanate and/or isophorone diisocyanate including isocyanurate
and biuret derivatives thereof with hydroxyalkyl (meth)acrylates
such as hydroxyethyl (meth)acrylate and/or hydroxypropyl
(meth)acrylate. Examples of suitable polyester (meth)acrylates are
the reaction products of (meth)acrylic acid or anhydride with
polyols, such as dials, trials and tetraols, including alkylated
polyols, such as propoxylated diols and trials. Examples of
suitable polyols include 1,4-butane diol, 1,6-hexane dial,
neopentyl glycol, trimethylol propane, pentaerythritol and
propoxylated 1,6-hexane diol. Examples of suitable polyester
(meth)acrylates include glycerol tri(meth)acrylate,
trimethylolpropane tri(meth)acrylate, pentaerythritol
tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate.
Mixtures of polyurethane (meth)acrylates, and polyester
(meth)acrylates may be used.
[0064] In addition to (meth)acrylates, (meth)allyl compounds or
prepolymers may be used either alone or in combination with
(meth)acrylates. Examples of (meth)allyl compounds include
polyallyl ethers such as the diallyl ether of 1,4-butane diol and
the allyl ether of trimethylol propane. Examples of other
(meth)allyl compounds include polyurethanes containing (meth)allyl
groups. For example, reaction products of polyisocyanates such as
1,6-hexamethylene diisocyanate and/or isophorone diisocyanate
including isocyanurate and biuret derivatives thereof with
hydroxy-functional allyl ethers, such as the monoallyl ether of
1,4-butane diol and the diallylether of trimethylol propane can be
used.
[0065] Isocyanate functionality may be incorporated into a
coreactive component in a number of ways. The polyurethane
(meth)acrylate or the polyurethane (meth)allyl compound may be
prepared in a manner such that the reaction product contains
unreacted isocyanate groups. For example, the above-mentioned
reaction product of 1,6-hexamethylene diisocyanate and/or
isophorone diisocyanate with hydroxyethyl (meth)acrylate and/or
hydroxypropyl (meth)acrylate are reacted in an NCO/OH equivalent
ratio of greater than 1. Alternately, such reaction products may be
prepared such that they are isocyanate free, i.e., NCO/OH
equivalent ratio equal to or less than 1, and a separate isocyanate
compound such as a polyisocyanate may be included in the coreactive
component.
[0066] A polythiol coreactive component refers to polyfunctional
compounds containing two or more thiol-functional groups (--SH).
Suitable polythiol-functional compounds include polythiols having
at least two thiol groups including monomers and prepolymers. A
polythiol may have ether linkages (--O--), thioether linkages
(--S--), including polysulfide linkages (--S.sub.x--), where x is
at least 2, such as from 2 to 4, and combinations of such
linkages.
[0067] Examples of suitable polythiols include compounds of the
formula R.sup.1--(SH).sub.n, where R.sup.1 is a polyvalent organic
moiety and n is an integer of at least 2, such as from 2 to 6.
[0068] Examples of suitable polythiols include esters of
thiol-containing acids formed by reacting a thiol-containing acid
of formula HS--R.sup.2--COOH where R.sup.2 is an organic moiety
with a polyhydroxy compounds of the structure R.sub.3--(OH).sub.n
where R.sup.3 is an organic moiety and n is at least 2, such as
from 2 to 6. These components may be reacted under suitable
conditions to give polythiols having the general structure
R.sup.3--(OC(O)--R.sup.2--SH).sub.n wherein R.sup.2, R.sup.3 and n
are as defined above.
[0069] Examples of thiol-containing acids include thioglycolic acid
(HS--CH.sub.2COOH), .alpha.-mercaptopropionic acid
(HS--CH(CH.sub.3)--COOH) and .beta.-mercaptopropionic acid
(HS--CH.sub.2CH.sub.2COCH) with poly hydroxy compounds such as
glycols, triols, tetraols, pentaols, hexaols, and mixtures thereof.
Other suitable polythiols include ethylene glycol
bis(thioglycolate), ethylene glycol bis(.beta.-mercaptopropionate),
trimethylolpropane tris (thioglycolate), trimethylolpropane tris
(.beta.-mercaptopropionate), pentaerythritol tetrakis
(thioglycolate) and pentaerythritol tetrakis
(.beta.-mercaptopropionate), and mixtures thereof.
[0070] Certain thermosetting compositions provided by the present
disclosure may employ Michael addition reactive components. The
reactive components may include primary amine-functional components
and acrylate, maleic, or fumaric-functional components. Compounds
that are useful primary amine-functional components include
polyoxyalkyleneamines containing two or more primary amine groups
attached to a backbone, derived, for example, from propylene oxide,
ethylene oxide, or a mixture thereof. Examples of such amines
include those available under the designation JEFFAMINE.TM. from
Huntsman Corporation. Such amines can have a molecular weight
ranging from 200 Daltons to 7500 Daltons, such as, for example,
JEFFAMINE.TM. D-230, D-400, D-2000, T-403, and T-5000. Compounds
useful as acrylate functional components include the acrylate
functional components listed previously as embodiments of
(poly)methacrylate. Compounds useful as maleic or fumaric
components include polyesters prepared from maleic anhydride,
maleic acid, fumaric acid, or their corresponding C.sub.1-6 alkyl
esters.
[0071] A Michael acceptor group refers to an activated alkenyl
group such as an alkenyl group proximate to an electron-withdrawing
group such as a ketone, nitro, halo, nitrile, carbonyl, or nitro
group. Examples of Michael acceptor groups include vinyl ketone,
vinyl sulfone, quinone, enamine, ketimine, aldimine, oxazolidine,
acrylate, acrylate esters, acrylonitrile, acrylamide, maleimide,
alkylmethacrylates, vinyl phosphonates, and vinyl pyridines.
[0072] Suitable examples of catalysts for Michael addition
chemistries include tributylphosphine, triisobutylphosphine,
tri-tertiary-butylphosphine, trioctyl phosphine,
tris(2,4,4-trimethylpentyl)phosphine, tricyclopentylphosphine,
tricyclohexalphosphine, tri-n-octylphosphine,
tri-n-dodecylphosphine, triphenyl phosphine, and dimethyl phenyl
phosphine.
[0073] Thermosetting compositions used in producing
three-dimensional objects can include various additives such as
rheology modifiers (e.g., silica or other fillers), flow control
agents, plasticizers, stabilizers, wetting agents, dispersing
auxiliaries, deformers, and adhesion promoters. In addition,
three-dimensional printing of a thermosetting composition can
include deposition of a thermosetting composition within a mold to
provide temporary structural integrity to the object during the
printing process.
[0074] Because the thermosetting compositions can have a low
viscosity compared to thermoplastic compositions it is possible to
use high filler concentrations. The high filler concentrations can
be used to modify the properties of the finished object such as the
mechanical, thermal, and/or electrical properties of the finished
object. Thus, the use of high filler concentrations facilitated by
the use of three-dimensional thermosetting compositions can greatly
expand the design possibilities of three-dimensional printing.
Furthermore, thermosetting compositions can be provided having
superior solvent and chemical resistance.
[0075] Examples of suitable fillers include fumed silica such as
Cabosil.RTM. TS720 available from Cabot Corporation and
precipitated silica such as Lo-Vel.RTM..TM. or Hi Sil.RTM. silicas
available from PPG Industries. A curable composition provided by
the present disclosure can comprise, for example, from 1 wt % to 40
wt % filler, from 1 wt % to 30 wt % filler, from 1 wt % to 25 wt %
filler, from 5 wt % to 25 wt % filler, or from 10 wt % to 20 wt %
filler, where wt % is based on the total weight of the curable
composition. A filler may be included in the A component of a
two-part system, may be included in the B part of a two-component
system, or a filler may be included in both the A part and the B
part.
[0076] A filler can be a low density filler characterized by, for
example, a specific gravity less than 0.7, less than 0.3, or less
than 0.1. Use of a low density filler can provide a
three-dimensional printed object having a low specific gravity,
such as from 0.8 to 1, or from 0.7 to 0.9.
[0077] A filler can be an electrically-conductive filler and can be
used to impart electrically conductivity and/or EMI/RFI shielding
effectiveness to a three-dimensional printed object. For example,
an electrically conductive printed object can be characterized by a
sheet resistance less than 0.5 .OMEGA./cm.sup.2 or less 0.15
.OMEGA./cm.sup.2. For example, an electrically conductive printed
object can provide effective EMI/RFI over a frequency range from 1
MHz to 18 GHz, or a subrange between 1 MHz to 18 GHz.
[0078] Suitable fillers also include magnetic fillers and opaque
fillers.
[0079] Three-dimensional printed objects can be fabricated using
the compositions provided by the present disclosure. A
three-dimensional printed object can be fabricated by deposited
successive layers of a compositions comprising coreactive
components. The compositions can be deposited, for example, using
extrusion or using inkjet printing techniques.
[0080] Extrusion of coreactive components is well known. The
coreactive components can be mixed in a barrel head pushed under
pressure through a suitably shaped nozzle. The extruded composition
or extrusion can be characterized by a cross-sectional profile. The
cross-sectional profile can be characterized by a constant ratio
the coreactive components or by a variable ratio of the coreactive
components, where the ratio can refer to the mole % ratio of the
coreactive components, by the equivalents ratio of the functional
groups, the wt % ratio of the reactive components, or other useful
ratio. An inhomogeneous composition across the cross-sectional
profile of an extrusion can be useful to impart different
properties to different parts of the profile. For example, it may
be useful to impart solvent resistance or electrically conductive
properties to the outer portion of a profile. To facilitate
adhesion between adjacent or adjoining layers such as underlying or
overlying layers, it may be useful to include an excess of one or
more of the coreactive functional groups. For example, an top
surface or a portion of a top surface of a layer may have an excess
of a first coreactive functional group, and a bottom surface or a
portion of a bottom surface of an overlying layer may have an
excess of a second coreactive functional group, where the first and
second coreactive functional groups are reactive with each other.
In this way, formation of covalent bonding between the adjoining
layers is facilitated and the physical integrity of a finished
three-dimensional printed object can be increased.
[0081] The rate of the curing reaction between the coreactive
components can also be controlled such that the reaction is not
complete when a subsequent layer is deposited on an underlying
layer. In this way, coreactive components of an overlying layer can
react with the coreactive components of an underlying layer to
increase the strength between layers. Coreactive thermoset
materials with a high degree of crosslinking can also be used to
provide high solvent and chemical resistance to the finished
part.
[0082] The ability of an extruded curable composition to maintain
structural integrity and support an overlying layer of the
composition was quantified by correlating the dynamic modulus of
the curable composition and the desired properties. Desired
properties, also referred to as build criteria, include the ability
to maintain the shape of a deposited layer, the ability to support
one or more overlying layers, and the ability to adhere or co-react
with an adjacent layer. The viscoelasticity of a curable
composition can be determined using a rotational rheometer to
measure the shear storage modulus G' and the shear loss modulus
G''. For example, the dynamic modulus of polyurea compositions that
did not meet the build criteria are shown in FIG. 1 and the dynamic
modulus of polyurea compositions that met the build criteria are
shown in FIG. 2. In FIGS. 1 and 2, the initial G' and G'' of a
curable composition immediately after mixing is shown by the open
squares and the G' and G'' 6 minutes after mixing is shown by the
solid circles. A line connects the initial and 6-minute measures
for a particular coreactive composition. A G' of 1,500 Pa is shown
by the solid vertical line, and a G' of 1,000,000 Pa is shown by
the dashed vertical line. A G'' of 600,000 Pa is shown by the
dashed horizontal line. Coreactive compositions meeting
three-dimensional printing build criteria can exhibit the following
properties: (1) an initial G''/G' ratio less than 2; (2) an initial
G' greater than 1,500 Pa; (3) a 6 min G' greater than 500,000 Pa;
and (4) a 6 min G'' greater than 400,000 Pa. Coreactive
compositions meeting three-dimensional printing build criteria can
exhibit the following properties: (1) an initial G''/G' ratio less
than 1.5; (2) an initial G' greater than 2,000 Pa; (3) a 6 min G'
greater than 10.sup.6 Pa; and (4) a 6 min G'' greater than 600,000
Pa. The initial G' and initial G'' refers to the shear storage and
shear loss modulus, respectively, immediately after combining the
A-functional and B-functional components, such as an
isocyanate-functional A component and an amine-functional B
component, and the 6 min G' and 6 min G'' refer to the shear
storage and shear loss modulus, respectively, 6 minutes after the A
and B components are combined. The values for the shear storage
modulus G' and the shear loss modulus G'' can be measured using an
Anton Paar MCR 301 or 302 rheometer with a gap set to 1 mm, with a
25 mm-diameter parallel plate spindle, and an oscillation frequency
of 1 Hz and amplitude of 0.3%. The tests can be performed under
ambient conditions with the temperature of the rheometer plate set
to be 25.degree. C.
[0083] Three-dimensional objects printed according to methods
provided by the present disclosure provide benefits over previous
3D printed objects in both the process for producing the object and
in the properties of final object. For example, the deposition
methods may not require any use of added heat, therefore avoiding
the creation of stress buildup in the finished object during
cooling as occurs with three-dimensional printing of thermoplastic
materials. The coreactive compositions provided by the present
disclosure can have sufficiently low viscosity that the
compositions may be pumped and printed quickly and accurately. By
using coreactive compositions that react fast and remain in place
following deposition, improved control over the shape and
dimensions of a printed object may be realized. In addition, the
coreactive compositions provided by the present disclosure may
include materials that provide additional properties to the object
such as magnetic or conductive including electrical and/or
thermally conductive, properties, and strength. Strengthening
components include, for example, carbon fiber, glass fiber, and
graphene. Colorants such as pigments or dyes can also be included
in a printing composition. For coreactive compositions that
crosslink quickly, strength in the printed object allows for rapid
addition of further layers on top of the previously printed portion
of the object. Another benefit of the disclosed materials and
methods is strength as provided in the "z direction" of the printed
object, where the x and y direction are the general planes of the
building of the three-dimensional object. Traditional
three-dimensional printing provides minimal adhesion between layers
of the printed object, particularly when thermoplastic materials
are used. By providing material that forms covalent crosslinks
between successive layers, the final printed object can have
increased strength in the z direction.
[0084] The use of low viscosity coreactive or thermoset
compositions can facilitate deposition at room temperature thereby
avoiding the high temperature print heads characteristic of
thermoplastic three-dimensional printing apparatus. The use of
thermosetting materials can facilitate the use of simple and light
weight print heads that can be moved rapidly and precisely and can
further simplify the various drive mechanisms.
[0085] Depending in part on control of the rheology profile and
cure rate of the thermosetting compositions, it is possible to
rapidly build parts with high structural integrity. The structural
strength between adjacent layers can also facilitate the ability to
construct shapes that overhang an underlying layer.
[0086] Three-dimensional printed objects can also be fabricated
using inkjet printing. Inkjet printing three-dimensional printed
objects are generally known in the art. In inkjet printing methods
the coreactive components may be deposited sequentially and/or
simultaneously. The at least two coreactive can be deposited using
separate nozzles. The coreactive components can be deposited on top
of each other and/or adjacent to each other. For inkjet printing, a
composition can be characterized by a viscosity less than 30 cP; a
surface tension of 30 mN/m to 50 nM/m; a contact angle on glass of
less than 20 degrees; and a contact angle on polyethylene
terephthalate of less than 40 degrees. For inkjet printing the
viscosity of the deposited composition can be from about 10 cP to
about 30 cP, from about 10 cP to about 20 cP, or from about 5 cP to
about 15 cP.
[0087] The at least two coreactive components can be deposited from
a single nozzle. In such cases the coreactive components can be
mixed and deposited before the curing reaction significantly
proceeds, or the coreactive components may have, for example, a
sufficiently slow curing rate that they remain in liquid form
following mixing. The slowly reacting components can be deposited
and a catalyst can then be deposited from a separate nozzle to
initiate the curing reaction between the two coreactive components.
Rather than be deposited as large droplets, the coreactive
components can be deposited as a spray. Deposition in the form of a
spray can facilitate the ability of the two coreactive components
to mix prior to deposition. Because reactive thermoset compositions
can have low viscosities, compared to thermoplastic compositions,
deposition using sprays can be facilitated.
[0088] It should be understood that, where not mutually exclusive,
the various features of the embodiments of the present disclosure
described, shown and/or claimed herein may be used in combination
with each other. In addition, the following Examples are presented
to demonstrate the general principles of the methods and
compositions provided by the present disclosure. All amounts listed
are described in parts by weight, unless otherwise indicated. The
invention should not be considered as limited to the specific
Examples presented.
EXAMPLES
Example 1
Rheology Characterization
[0089] The rheology of three-dimensional printing formulations was
determined using an Anton Paar 301 or 302 rheometer. Two-component
(A pack: amine; B pack: isocyanate) samples were mixed using either
a dual-channel syringe pump (Kd Scientific) or a hand mixing gun
(Nordson), and then immediately deposited onto the rheometer to
fill the sample gap (1 mL to 2 mL). A disposable sample plate
(Anton Paar, Cat. No 4847) was placed on the rheometer and used as
the bottom plate in the measurements. A disposable parallel plate
spindle with a diameter of 25 mm (PP25) was used for the
measurements. The spindle was brought toward the sample immediately
after loading, with the gap set at 1 mm. An oscillation measurement
(frequency 1 Hz, amplitude 0.3%) was then applied. Rheological
parameters (G', G'', tan .delta., |.delta.*|) were recorded over
time. The tests were performed under ambient condition with the
temperature of the rheometer plate set to be 25.degree. C. The
polyurea formulations evaluated are provided in Table 2.
TABLE-US-00002 TABLE 2 Polyurea formulations. A pack B pack
Particle Particle NCO/NH Amine Particle content Isocyanate Particle
content Equivalents Formulation Component(s) type (wt %)
Component(s) type (wt % Ratio A Desmophen .RTM. None 0 Desmodur
.RTM. XP None 0 1.42 NH1220.sup.1 2410.sup.4 B Desmophen .RTM.
Cabosil .RTM. 2 Desmodur .RTM. XP Cabosil .RTM. 2 1.42 NH1220
TS720.sup.9 2410 TS720 C Desmophen .RTM. Cabosil .RTM. 4 Desmodur
.RTM. XP Cabosil .RTM. 4 1.42 NH1220 TS720 2410 TS720 D 75 parts
Cabosil .RTM. 5 90 parts PTMEG None 0 1.25 Jeffamine .RTM. TS720
2000/IPDI T5000.sup.2/25 Prepolymer.sup.5, 10 parts parts of
Clearlink .RTM. PTMEG650/IPDI 1000.sup.3 Prepolymer.sup.6 E 70
parts PPG 5 80 parts PTMEG None 0 1.42 Jeffamine .RTM. precipitated
2000/IPDI T5000/30 Silica.sup.10 Prepolymer, 20 parts parts of
PTMEG Clearlink .RTM. 650/IPDI 1000 Prepolymer F 55 parts None 0 60
parts PTMEG None 0 1 Jeffamine .RTM. 2000/IPDI T5000/45 Prepolymer,
40 parts parts of PTMEG Clearlink .RTM. 650/IPDI 1000 Prepolymer G
Desmophen .RTM. Cabosil .RTM. 5 Desmodur .RTM. XP Cabosil .RTM. 5
1.42 NH1220 TS720 2410 TS720 H 60 parts PPG 24 80 parts PTMEG None
0 1 Jeffamine .RTM. precipitated 2000/IPDI T5000/40 Silica
Prepolymer, 20 parts parts of PTMEG Clearlink .RTM. 650/IPDI 1000
Prepolymer I 64 parts PPG 24 60 parts PTMEG None 0 1.42 Jeffamine
.RTM. precipitated 2000/IPDI T5000/36 Silica Prepolymer, 40 parts
parts of PTMEG Clearlink .RTM. 650/IPDI 1000 Prepolymer J 47 parts
PPG 24 60 parts None 0 1 Jeffamine .RTM. precipitated
PTMEG2000/IPDI T5000/53 Silica Prepolymer, 40 parts parts of PTMEG
Clearlink .RTM. 650/IPDI 1000 Prepolymer .sup.1Desmophen .RTM.
NH1220, amine-functional aspartic acid ester, available from Bayer
Corporation. .sup.2Jeffamine .RTM. T5000, polyoxyalkylene primary
amine of approximately 5000 MW, available from Huntsman
Corporation. .sup.3Clearlink .RTM. 1000, aliphatic secondary amine,
available from Dorf-Ketal Chemicals, LLC. .sup.4Desmodur .RTM. XP
2410, an asymmetric trimer of hexamethylene diisocyanate, available
from Bayer Material Science. .sup.5PTMEG 2000/IPDI prepolymer,
reaction product of isophorone diisocyanate and TERATHANE .TM.
2000.sup.7. .sup.6PTMEG 650/IPDI prepolymer, reaction product of
isophorone diisocyanate and TERATHANE .TM. 650.sup.8, as disclosed
in U.S. Application Publication No. 2013/0344340, paragraph [0181].
.sup.7TERATHANE .TM. 2000, polythioether diol of approximately 2000
molecular weight, available from Invista. .sup.8TERATHANE .TM. 650,
polythioether diol of approximately 650 molecular weight, available
from Invista. .sup.9Cabosil .RTM. TS720, fumed silica available
from Cabot Corporation. .sup.10Lo-Vel .TM. 27 available from PPG
Industries, Inc.
[0090] Graphs showing the dynamic modulus of the deposited polyurea
exhibiting Build 0 capability is provided in FIG. 1 and exhibiting
Build 4 capability is provided in FIG. 2. Build Capability refers
to a subjective assessment of the ability of a composition to
produce a successful three-dimensional printed object. Criteria
used to assess Build capability include the ability to mechanically
support overlying layers, the ability to maintain the deposited
shape and dimensions, and the ability to adhere or bond to adjacent
layers. A value of 0 represents unacceptable build capability and a
value of 5 represents excellent build capability.
[0091] The values for which tan .delta. (G'=G'') is 1 is shown as a
diagonal line. For values of tan .delta. greater than 1, the
material has a stronger inelastic component and for values of tan
.delta. less than 1, the material has a stronger elastic component.
The measurements indicated by the open squares were obtained
immediately after the material was deposited on the rheometer
(t=0). The measurements indicated by the solid circles were
obtained 6 minutes after deposition and when the material had
partially cured. Lines connect the measurements for on the same
formulation.
[0092] It was empirically determined that materials having a shear
storage modulus G' and shear loss modulus G'' equal to or greater
than 10.sup.6 Pa were sufficiently strong to support overlying
build layers and could sufficiently adhere to adjacent layers. This
area is represented by the box in the upper right hand corner of
the dynamic modulus plot. It was also determined empirically that
modulus values that provided a successful build included:
[0093] (1) a value of G''/G' less than 1.5;
[0094] (2) an initial shear storage modulus G' greater than 2,000
Pa;
[0095] (3) a 6 min G' greater than 1,000,000 Pa; and
[0096] (4) a 6 min G'' greater than 600,000 Pa.
The initial conditions are represented by values of G' and G''
below the tan .delta. line and to the left of the vertical line
representing G' greater than 600,000 Pa.
[0097] The moduli (shear storage modulus G' and shear loss modulus
G'') for each of the polyurea formulations included in Table 2 is
provided in Table 3.
[0098] In the examples, the build capability tests on the
formulations shown in Table 2 were performed using a dual channel
syringe pump, affixed with a helical static mixer with a 2 mm
orifice to dispense the formulation onto the substrate and build.
The material was dispensed at a rate of 5 mL/min to 15 mL/min with
the volume ratio of the two components adjusted to achieve the
stoichiometry listed in Table 3. To assess the build capability of
each formulation, a cube with a base approximately 2.5 cm.times.2.5
cm was built by hand. The build capability was rated on a scale of
0 to 5 with 5 being the best. A build rating of 0 indicated that
the material flowed extensively and a three dimensional structure
was not produced. A build rating of 4 indicated that many layers
could be printed without the cube collapsing or warping, but some
limited reflow of the composition occurred after deposition. A 5
build rating indicated that many layers could be printed without
the cube collapsing or warping, with no reflow of the composition
after deposition.
TABLE-US-00003 TABLE 3 Dynamic modulus parameters for the polyurea
formulations in Table 2. G'' initial G' initial G' at 6 G'' at 6
G''/G' Build Formulation (Pa) (Pa) min (Pa) min (Pa) (tan .delta.)
Capability A 389 1.351 463830 705530* 288 0 B 191 73.5 413000
871000* 2.60 0 C 701 1140 1020000* 1850000* 0.61* 0 D 25354 15005*
373470 288510 1.69 0 E 25038 16595* 661540 349840 1.51 0 F 46274
40721* 194260 136930 1.14* 0 G 5689.2 4304* 4515600* 3707700* 1.32*
4 H 323230 333310* 2289900* 803550* 0.97* 4 I 269730 220640*
2116600* 1090300* 1.22* 4 J 1512300 3757600* 5328400* 1655700*
0.40* 4
[0099] The values of the parameters meeting successful build
criteria (1)-(4) are identified in Table 3 with an asterisk.
Formulations G-J met each of the build criteria (1)-(4).
[0100] Whereas particular embodiments of this invention have been
described above for purposes of illustration, it will be evident to
those skilled in the art that numerous variations of the details of
the present invention may be made without departing from the
invention as defined in the appended claims.
* * * * *