U.S. patent application number 12/769509 was filed with the patent office on 2010-11-04 for inorganic composite.
This patent application is currently assigned to Tundra Composites, LLC.. Invention is credited to Kurt E. Heikkila, John S. Kroll, Rodney K. Williams.
Application Number | 20100280164 12/769509 |
Document ID | / |
Family ID | 43030593 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100280164 |
Kind Code |
A1 |
Heikkila; Kurt E. ; et
al. |
November 4, 2010 |
Inorganic Composite
Abstract
The invention relates to a nonmetallic inorganic or mineral
particulate polymer composite having enhanced viscoelastic and
rheological properties.
Inventors: |
Heikkila; Kurt E.; (Marine
on the St. Croix, MN) ; Williams; Rodney K.; (Stacy,
MN) ; Kroll; John S.; (Blaine, MN) |
Correspondence
Address: |
PAULY, DEVRIES SMITH & DEFFNER, L.L.C.
Plaza VII-Suite 3000, 45 South Seventh Street
MINNEAPOLIS
MN
55402-1630
US
|
Assignee: |
Tundra Composites, LLC.
White Bear Lake
MN
|
Family ID: |
43030593 |
Appl. No.: |
12/769509 |
Filed: |
April 28, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61173791 |
Apr 29, 2009 |
|
|
|
Current U.S.
Class: |
524/443 ;
524/493; 524/494 |
Current CPC
Class: |
C08J 2327/20 20130101;
C08J 2327/16 20130101; C08K 2201/005 20130101; C08K 3/22 20130101;
C08J 2327/18 20130101; C08K 7/28 20130101; C08K 7/28 20130101; C08K
9/00 20130101; C08J 5/04 20130101; Y10T 428/249974 20150401; C08K
9/04 20130101; C08L 21/00 20130101; B60C 1/00 20130101; C08K
2003/2227 20130101; C08L 21/00 20130101 |
Class at
Publication: |
524/443 ;
524/493; 524/494 |
International
Class: |
C08K 3/34 20060101
C08K003/34; C08K 3/36 20060101 C08K003/36; C08K 3/40 20060101
C08K003/40 |
Claims
1. An inorganic particle and polymer composite comprising: (a)
about 30 to 87 vol.-% of an inorganic mineral particle having a
particle size P.sub.S greater than about 5 microns having a coating
of about 0.005 to 5 wt-% of an interfacial modifier, the percentage
based on the composite; and (b) a polymer phase.
2. The composite of claim 1 wherein the particle comprises a
mineral having a particle size P.sub.S of about 10 to 1000
microns.
3. The composite of claim 1 wherein the particle comprises a
mineral having a particle size P.sub.S of about 10 to 200
microns.
4. The composite of claim 1 wherein the particle comprises a
mineral having a particle size P.sub.S of about 15 to 250
microns;
5. The composite of claim 1 wherein the circularity of the mineral
is 12.5 to.sub.--50.
6. The composite of claim 1 wherein the particle comprises a
ceramic having a particle size P.sub.S of about 5 to 150
microns.
7. The composite of claim 1 wherein the composite has a tensile
strength of about 0.1 to 15 times that of the base polymer.
8. The composite of claim 1 wherein the composite has a tensile
strength of about 5 to 25 times that of the base polymer.
9. The composite of claim 1 wherein the composite has a tensile
elongation of about 0.10% and 100% of the base polymer.
10. The composite of claim 1 wherein the composite has a tensile
elongation of about 15% and 100% of the base polymer.
11. The composite of claim 1 wherein the composite has a tensile
strength of about 0.10 to 20 times that of the base polymer and a
tensile elongation of about 15% and 100% of base polymer.
12. The composite of claim 1 wherein the composite has a
thermoplastic shear of at least 5 sec.sup.-1.
13. The composite of claim 1 wherein the composite has a tensile
strength of at least 0.2 MPa and a thermoplastic shear of at least
5 sec.sup.-1.
14. The composite of claim 1 wherein the composite comprises
greater than 30 vol.-% of the inorganic material having a particle
size of 10 to 200 microns.
15. The composite of claim 1 wherein the composite comprises
greater than 50 vol.-% of the inorganic mineral.
16. The composite of claim 1 wherein the composite comprises a
particulate wherein the majority of the particulates having a
particulate size P.sub.S of about 10 to 1000 microns; and a
fluoropolymer phase.
17. The composite of claim 1 wherein the inorganic mineral has a
particle size P.sub.S of about 10 to 200 microns and the composite
additionally comprises a second particulate with a particle size
P.sub.S.sup.1 that differs from the inorganic composite by at least
5 microns.
18. The composite of claim 17 wherein the inorganic mineral has a
particle size P.sub.S according to the formula P.sub.S<2
P.sub.S.sup.1 or P.sub.S>0.5 P.sub.S.sup.1; wherein P.sub.S is
the particle size of the inorganic mineral and P.sub.S.sup.1 is the
particle size of the second particulate.
19. The composite of claim 17 wherein the second particulate
comprises a ceramic particulate, a glass microsphere, a solid glass
sphere, or a second inorganic composite.
20. The composite of claim 1 wherein the second particle comprises
a hollow glass sphere having a particle size P.sub.S of about 10 to
300 microns.
21. The composite of claim 1 wherein the second particle comprises
a solid glass sphere having a particle size P.sub.S of about 5 to
1000 microns.
22. The composite of claim 1 wherein the particle comprises a
silica having a particle size P.sub.S of about 5 to 500
microns.
23. The composite of claim 1 wherein the particle comprises a
silica having a particle size P.sub.S of about 75 to 500
microns.
24. The composite of claim 22 wherein the silica particle comprises
silica sand.
25. The composite of claim 1 wherein the particle comprises
zirconium silicate.
26. The composite of claim 22 wherein the polymer comprises a
fluoropolymer.
27. The composite of claim 26 wherein the polymer comprises a
fluoroelastomer.
28. The composite of claim 1 wherein the polymer comprises a
polyamide.
29. The composite of claim 1 wherein the polymer comprises a
nylon.
30. The composite of claim 1 wherein the polymer comprises a
poly(ethylene-co-vinyl acetate).
31. The composite of claim 1 wherein the polymer comprises a
synthetic rubber.
32. The composite of claim 1 wherein the polymer comprises a
polyolefin.
33. The composite of claim 1 wherein the polymer comprises a
thermoset polymer.
34. The composite of claim 1 wherein the polymer comprises a
high-density polyolefin.
35. The composite of claim 1 wherein the polymer comprises a
polyvinyl chloride.
36. The composite of claim 1 wherein the inorganic mineral particle
comprises a circularity of about 14 to 50.
37. The composite of claim 1 wherein the second particle comprises
a mixture of particles of differing composition.
38. The composite of claim 1 wherein the composite comprises about
0.01 to 5 wt % of an interfacial modifier based on the
composite.
39. The composite of claim 1 wherein the particle has an excluded
vol. of about 13 vol.-% to about 70 vol.-%.
40. The composite of claim 1 wherein the particle has an excluded
vol. of about 13 vol.-% to about 60 vol.-%.
41. The composite of claim 1 wherein the composite comprises an
organic or inorganic pigment.
42. The composite of claim 1 wherein the composite comprises an
organic dye.
43. A particulate polymer composite comprising a non-metal,
inorganic or mineral particle in a polymer phase, the composite
comprising: (a) about 90 to 40 vol.-% of an inorganic mineral
particle, having a density greater than 0.10 gm-cm.sup.-3 and less
than 5 gm-cm.sup.-3, a particle size P.sub.S greater than 10
microns, a circularity greater than 14 and an aspect ratio less
than 3; and (b) about 10 to 70 vol.-% of a polymer phase; wherein
the particulate comprising a layer comprising about 0.005 to 3
wt.-% of an interfacial modifier; and the composite density is
about 0.9 to 15 gm-cm.sup.-3.
44. The composite of claim 43 further comprising a particle with a
circularity index of 12.5 to 25.0.
45. The composite of claim 43 wherein the density is about 1 to 5
gm-cm.sup.-3.
46. The composite of claim 43 wherein the density is about 1 to 2
gm-cm.sup.-3.
47. A shaped article comprising the composite of claim 43 wherein
in the polymer composite comprises about 87 to 48 vol.-% of a
particulate having a particle size P.sub.S greater than 10 microns,
and having a particle size P.sub.S distribution having at least 10
wt.-% of a particulate within about 10 to 100 microns, at least 10
wt.-% of the polymer particulate within about 100 to 500 microns, a
circularity greater than 12.5 and an aspect ratio less than 1:3;
about 13 to 51 vol.-% of a polymer phase.
48. A method of forming an inorganic and polymer composite material
which comprises forming a extrudible mass comprising a polymer
phase and a particle phase, the particle phase comprising a coating
of an interfacial modifier in an amount of about 0.005 to 5.0 wt-%
based on the composite, the particles comprising a first particle
particulate having a circularity of greater than about 15 and a
second substantially round particulate having a circularity of
about 12.5 to 15; the second particulate comprising greater than 5
vol.-% of the composite wherein upon extrusion, the shear on the
extrudible mass, the wear of an extruder and the extrusion pressure
is reduced.
49. The method of claim 48 wherein the second substantially round
particle is used at about 5 to 80 vol.-% of a particulate phase
comprising 30 to 82 vol.-% of the composite.
50. The method of claim 48 wherein the circularity of the inorganic
particle comprises circularity about 15 to 50 and the second
substantially round particulate comprises circularity about 12.5 to
25.
51. The method of claim 48 wherein the particle size P.sub.S of the
first particle is 20 to 50 microns and the particle size P.sub.S of
the second particle is about 12.5 to 20 microns.
52. A shaped article comprising the composite of claim 43 wherein
in the polymer composite comprises about 87 to 48 volume-% of a
particulate having a particle size greater than 10 microns, and
having a particle size distribution having at least 10 wt.-% of a
particulate within about 10 to 100 microns, at least 10 wt.-% of
the polymer particulate within about 100 to 500 microns, a
circularity greater than 12.5 and an aspect ratio less than 1:9;
about 13 to 51 vol-% of a polymer phase.
53. The shaped article of claim 52 wherein the article is dental
article, a transportation bumper, a commercial or residential
weather strip, an abrasive layer, a vapor resistant hose, a
transportation interior panel, a sealant for a fenestration unit or
installation, a structural member for a sound box, a transportation
brake pad, an LED heat dissipation fixture, a refrigeration unit
thermal seal, and a fenestration composition that act as a thermal
or barrier to mass transfer.
54. The shaped article of claim 53 wherein the transportation panel
is a sound deadening panel for an automotive and boat
application.
55. The shaped article of claim 53 wherein the fenestration unit is
insulated glass unit.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/173,791, filed Apr. 29, 2009, which
application is hereby incorporated by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The invention relates to a composite of a nonmetallic,
inorganic mineral particle and a polymer with modifiable properties
to produced enhanced products. The novel properties are produced in
the composite by novel interactions of the components. The
inorganic mineral particle polymer composite materials are a unique
combination of inorganic, non metallic or mineral typically
particulate components and a polymer material that optimizes the
composite structure and characteristics through blending the
combined polymer and inorganic mineral particle materials to
achieve true composite properties.
BACKGROUND OF THE INVENTION
[0003] Substantial attention has been paid to the creation of
composite materials with unique properties. Included in this class
of materials are materials with improved viscoelastic character,
varying densities, varying surface characteristics and other
properties which may be used to construct a material with improved
properties. As an example, silica sand has been commonly used in
applications such as abrasives. Sand paper is an example. However,
sandpaper will lose abrasion capacity in a relatively short period
of time depending on its application and its use over time,
[0004] Composite materials have been made for many years by
combining generally two dissimilar materials to obtain beneficial
properties from both. A true composite is unique because the
interaction of the materials provides the best properties and
characteristics of both components. Many types of composite
materials are known. Generally, the art recognizes that combining
metals of certain types and at proportions that form an alloy
provides unique properties in metal/metal alloy materials.
Metal/ceramic composites have been made typically involving
combining metal powder or fiber with clay materials that can be
sintered into a metal/ceramic composite.
[0005] Combining typically a thermoplastic or thermosetting polymer
phase with a reinforcing powder or fiber produces a range of filled
materials and, under the correct conditions, can form a true
polymer composite. A filled polymer, with the additive as filler,
cannot display composite properties. A filler material typically is
comprised of inorganic materials that act as either pigments or
extenders for the polymer systems. Fillers are often replacements
for a more expensive component in the composition. A vast variety
of fiber-reinforced composites have been made typically to obtain
fiber reinforcement properties to improve the mechanical properties
of the polymer in a specific composite.
[0006] Many of these materials containing polymer and particulate
are admixtures and are not true composites. Admixtures are
relatively easily separable into the constituent parts and, once
separated, display the individual properties of the components. A
true composite resists separation and displays enhanced properties
of the input materials whereas the individual input materials often
do not display the enhanced properties. A true composite does not
display the properties of the individual components but display the
unique character of the composite.
[0007] While a substantial amount of work has been done regarding
composite materials generally, the use of inorganic, non metallic
or mineral particles in a polymer composite has not been obtained.
Tuning the density the formation of these materials into a
composite of a polymer and an inorganic mineral or non-metal
provides novel mechanical and physical properties into the
composite and, when used, obtains properties that are not present
in other materials. A need exists for material that has tunable
density, low toxicity, and improved properties in terms of
increased conformance, elasticity, and pliability.
BRIEF DESCRIPTION OF THE INVENTION
[0008] The invention relates to a composite of a non metallic,
inorganic mineral particle and a polymer having improved and novel
properties. The material of the invention is provided through a
selection of non metallic, inorganic mineral particle specie,
particle size (P.sub.S) distribution, polymer type, molecular
weight, surface modification and processing conditions. The
particles have a specific and novel particle morphology that
cooperates with the components of the invention to provide the
needed properties to the composite. The material attains adjustable
chemical/physical properties through inorganic mineral particle
selection and polymer selection. The resulting composite materials
exceed the contemporary composites in terms of density, surface
character, reduced toxicity, improved malleability, improved
ductility, improved viscoelastic properties (such as tensile
modulus, storage modulus, elastic-plastic deformation and others)
electrical/magnetic properties, resistance to condition of
electricity, vibration or sound, and machine molding properties. We
have found that density and polymer viscoelasticity measured as
elongation are useful properties and useful predictive parameters
of a composite in this technology. In the production of useful
enhanced properties, the packing of the selected particle sizes
(P.sub.S, P.sub.S.sup.1, etc.), distribution population particles,
surface modification and the selection of the particulate or mixed
non-metal, inorganic or mineral particulate, will obtain the
enhanced properties, in part through novel extrusion
processing.
BRIEF DISCUSSION OF THE DRAWINGS
[0009] FIG. 1 through 14 shows the nature of the properties of the
composites of the invention.
DETAILED DISCUSSION OF THE INVENTION
[0010] The invention relates to novel composites made by combining
an inorganic, non-metallic or mineral particulate with a polymer to
achieve novel physical electrical surface and viscoelastic
properties. Any inorganic, non-metallic or mineral composition of
manner that can be formed into a particulate having a particle size
ranging from about 10 microns to about 1,500 microns can be used in
the invention. The maximum size is such that the particle size
(P.sub.S) of the particle is less than 20% of either the least
dimension or the thinnest part under stress in an end use article.
Such particles can be substantially spherical, but preferred
materials are rough and have substantial particle morphology, are
substantially amorphous or can achieve virtually any
three-dimensional shape formable by small particle size
materials.
[0011] Both thermoplastic and thermosetting resins can be used in
the invention. Such resins are discussed in more detail below. In
the case of thermoplastic resins, the composites are specifically
formed by blending the particulate and interfacial modifier with
thermoplastic and then forming the material into a finished
composite. Thermosetting composites are made by combining the
particulate and interfacial modifier with an uncured material and
then curing the material into a finished composite.
[0012] In both cases, the particulate material is typically coated
with an interfacial modifier, a surface chemical treatment that
supports or enhancing the final properties of the composite.
[0013] A composite is more than a simple admixture. A composite is
defined as a combination of two or more substances intermingled
with various percentages of composition, in which each component
results in a combination of separate materials, resulting in
properties that are in addition to or superior to those of its
constituents. In a simple admixture the mixed material have little
interaction and little property enhancement. One of the materials
is chosen to increase stiffness, strength or density. Atoms and
molecules can form bonds with other atoms or molecules using a
number of mechanisms. Such bonding can occur between the electron
cloud of an atom or molecular surfaces including
molecular-molecular interactions, atom-molecular interactions and
atom-atom interactions. Each bonding mechanism involves
characteristic forces and dimensions between the atomic centers
even in molecular interactions. The important aspect of such
bonding force is strength, the variation of bonding strength over
distance and directionality. The major forces in such bonding
include ionic bonding, covalent bonding and the van der Waals'
(VDW) types of bonding. Ionic radii and bonding occur in ionic
species such as Na.sup.+Cl.sup.-, Li.sup.+F.sup.-. Such ionic
species form ionic bonds between the atomic centers. Such bonding
is substantial, often substantially greater than 100 kJ-mol.sup.-1
often greater than 250 kJ-mol.sup.-1. Further, the interatomic
distance for ionic radii tend to be small and on the order of 1-3
.ANG.. Covalent bonding results from the overlap of electron clouds
surrounding atoms forming a direct covalent bond between atomic
centers. The covalent bond strengths are substantial, are roughly
equivalent to ionic bonding and tend to have somewhat smaller
interatomic distances.
[0014] The varied types of van der Waals' forces are different than
covalent and ionic bonding. These van der Waals' forces tend to be
forces between molecules, not between atomic centers. The van der
Waals' forces are typically divided into three types of forces
including dipole-dipole forces, dispersion forces and hydrogen
bonding. Dipole-dipole forces are a van der Waals' force arising
from temporary or permanent variations in the amount or
distribution of charge on a molecule.
TABLE-US-00001 TABLE 1 Summary of Chemical Forces and Interactions
Strength Proportional Type of Interaction Strength Bond Nature to:
Covalent bond Very strong Comparatively long r.sup.-1 range Ionic
bond Very strong Comparatively long r.sup.-1 range Ion-dipole
Strong Short range r.sup.-2 VDW Dipole-dipole Moderately strong
Short range r.sup.-3 VDW Ion-induced dipole Weak Very short range
r.sup.-4 VDW Dipole-induced Very weak Extremely short range
r.sup.-6 dipole VDW London dispersion Very weak.sup.a Extremely
short range r.sup.-6 forces .sup.aSince VDW London forces increase
with increasing size and there is no limit to the size of
molecules, these forces can become rather large. In general,
however, they are very weak.
[0015] Dipole structures arise by the separation of charges on a
molecule creating a generally or partially positive and a generally
or partially negative opposite end. The forces arise from
electrostatic interaction between the molecule negative and
positive regions. Hydrogen bonding is a dipole-dipole interaction
between a hydrogen atom and an electronegative region in a
molecule, typically comprising an oxygen, fluorine, nitrogen or
other relatively electronegative (compared to H) site. These atoms
attain a dipole negative charge attracting a dipole-dipole
interaction with a hydrogen atom having a positive charge.
Dispersion force is the van der Waals' force existing between
substantially non-polar uncharged molecules. While this force
occurs in non-polar molecules, the force arises from the movement
of electrons within the molecule. Because of the rapidity of motion
within the electron cloud, the non-polar molecule attains a small
but meaningful instantaneous charge as electron movement causes a
temporary change in the polarization of the molecule. These minor
fluctuations in charge result in the dispersion portion of the van
der Waals' force.
[0016] Such VDW forces, because of the nature of the dipole or the
fluctuating polarization of the molecule, tend to be low in bond
strength, typically 50 kJ mol.sup.-1 or less. Further, the range at
which the force becomes attractive is also substantially greater
than ionic or covalent bonding and tends to be about 3-10
.ANG..
[0017] In the van der Waals composite materials of this invention,
we have found that the unique combination of particulate, the
varying but controlled particle size of the particle component, the
modification of the interaction between the particulate and the
polymer, result in the creation of a unique van der Waals' bonding.
The van der Waals' forces arise between particulate atoms/crystals
in the particulate and are created by the combination of particle
size, polymer and interfacial modifiers in the composite.
[0018] In the past, materials not fully accurately characterized as
"composite" have merely comprised a polymer filled with particulate
with little or no van der Waals' interaction between the
particulate filler material. In the invention, the interaction
between the selection of particle size distribution and
interfacially modified polymer enables the particulate to achieve
an intermolecular distance that creates a substantial van der
Waals' bond strength. The prior art materials having little
viscoelastic properties, do not achieve a true composite structure.
This leads us to conclude that this intermolecular distance is not
attained in the prior art. In the discussion above, the term
"molecule" can be used to relate to a particle, a particle
comprising non-metal crystal or an amorphous aggregate, other
molecular or atomic units or sub-units of non metal or inorganic
mixtures. coin the composites of the invention, the van der Waals'
forces occur between collections of metal atoms that act as
"molecules" in the form of mineral, inorganic, or non-metal atom
aggregates.
[0019] The composite of the invention is characterized by a
composite having intermolecular forces between particles about 30
kJ-mol.sup.-1 and a bond dimension of 3-10 .ANG.. The particulate
in the composite of the invention has a range of particle sizes
such that about at least 5 wt.-% of particulate in the range of
about 10 to 500 microns and about at least 5 wt.-% of particulate
in the range of about 10 to 250 microns, and a polymer, the
composite having a van der Waals' dispersion bond strength between
molecules in adjacent particles of less than about 4 kJ-mol.sup.-1
and a bond dimension of 1.4 to 1.9 .ANG. or less than about 2
kJ-mol.sup.-1 and the van der Waals' bond dimension is about 1.5 to
1.8 .ANG..
[0020] In a composite, the reinforcement is usually much stronger
and stiffer than the matrix, and gives the composite its good
properties. The matrix holds the reinforcements in an orderly
high-density pattern. Because the reinforcements are usually
discontinuous, the matrix also helps to transfer load among the
reinforcements. Processing can aid in the mixing and filling of the
reinforcement or particulate. To aid in the mixture, an interfacial
modifier can help to overcome the forces that prevent the matrix
from forming a substantially continuous phase of the composite. The
composite properties arise from the intimate association obtained
by use of careful processing and manufacture.
[0021] We believe an interfacial modifier is an organic material
that provides an exterior coating on the particulate promoting the
close association (but with substantially no covalent bonding to
the polymer or particle) of polymer and particulate. Minimal
amounts of the modifier can be used including about 0.005 to 8
wt.-%, or about 0.02 to 3 wt. %. Such a coating can have a
thickness of about 0.01 to 1 micron.
[0022] For the purpose of this disclosure, the term "particulate"
typically refers to a material made into a product having a
particle size greater than 10 microns and having a particle size
distribution containing at least some particulate in the size range
of 10 to 4000 microns. The particles have a range of sizes and
circularity parameters. In a packed state, this particulate has an
excluded volume of about 13 to 61 vol.-% or about 30 to 75 vol.-%.
Alternatively, the particulate can have greater than about 30 vol.
%, greater than about 40 vol. % or about 40 to 70 vol.-% particle
loading. In this invention, the particulate can comprise two three
or more particulates sources, in a blend of materials of differing
chemical and physical nature. Regarding the particulate material,
the term a "majority of the particulate" indicates that while the
particulate can contain some small amount of small fines and some
particles that are large with respect to the recited range, the
majority (greater than 95%, 90%, 85%, etc.) fall within the recited
range and contribute to the physical properties of the
composite.
[0023] For the purpose of this disclosure, the term "non-metallic"
relates to a material substantially free of a metal in an oxidation
state, approximately 0.
[0024] For the purpose of this disclosure, the term "inorganic"
relates to a material substantially free of carbon in the form or
organic carbon or covalently bonded carbon compounds. Accordingly,
compounds such as calcium carbonate or sodium bicarbonate are
considered inorganic materials while most organic compounds
including small molecules such as methane, ethane, ethylene,
propylene, related polymer species, etc., are commonly considered
organic materials. Other particulate material can be used in the
inorganic compositions of the invention. Examples of such materials
are as follows.
[0025] A "mineral" is defined as an element or chemical compound
that is normally crystalline and that has been formed as a result
of geological processes (Ernest H. Nickel, 1995, The definition of
a mineral, The Canadian Mineralogist, vol. 33, pp. 689-690). For
the purpose of this invention, the term "inorganic mineral"
(mineral) is defined, as above, as an element or chemical compound
that is normally crystalline and that has been formed as a result
of geological processes. Other materials can be used in the
composites of the invention including ceramics, hollow and solid
glass spheres and other particulates.
[0026] A "hollow glass sphere or bubble" is defined as a glass body
having a generally spherical shape having a hollow interior. The
glass sphere typically has a particle size (P.sub.S) that ranges
from about 1 to 150 microns, typically about 10 to 120 microns,
preferably about 10 to 100 microns. The internal space within the
glass bubble typically ranges from about 5 to 120 microns, often
about 6 to 100 microns. Solid glass spheres can have similar
particle size (P.sub.S).
[0027] A ceramic particle is typically defined as an inorganic
crystalline oxide material. Ceramics are typically solid and inert.
Ceramic materials tend to be brittle, hard, strong in compression
and weak in shear or tension. Ceramics generally have a very high
melting point that is typically greater than 1,000.degree. C., but
often ranges from 1,800 to 3,000.degree. C. and in some cases even
higher. Traditionally, ceramic materials include various silicates,
materials derived from clay, such as kaolinite. More recent ceramic
materials include aluminum oxide, silicon carbide and tungsten
carbide. Other ceramics include oxides of aluminum and zirconium.
Non-oxide ceramics include metal carbides, metal borides, metal
nitrides and metal silicides.
[0028] A "inorganic mineral" as understood in the context of this
application includes natural inorganic materials that are not
ceramics as defined above. Inorganic compounds are considered to be
of a mineral, not biological origin. Inorganic minerals as
understood in this application do not include organo, metallic
chemistry compounds including metal ions surround by organic
ligands. Inorganic compound as minerals typically include inorganic
minerals that are found in nature or their synthetic equivalents.
Commonly available inorganic minerals include mineral carbonates,
mineral aluminates, mineral alumo-silicates, mineral oxides,
mineral hydroxides, mineral bicarbonates, mineral sulfates, mineral
fluorides, mineral phosphates, mineral alumo-phosphates, mineral
alumo-silicates. Examples of inorganic minerals include bauxite
(aluminum ore), calcium carbonate, calcium hydroxide, calcium
sulfate, cuprous and cupric sulfide, lead oxide, magnesium
carbonate, magnesium oxide, magnesium sulfate, magnesium alum
compounds, such as potassium alumo-silicate, potassium borate,
potassium carbonate, potassium sulfate and other compounds,
including sodium silicate, sodium sulfate, etc.
Particle Morphology Index
[0029] The interfacial modification technology depends on the
ability to isolate the particles from that of the continuous
polymer phase. The isolation of the particulates requires placement
of a continuous molecular layer(s) of interfacial modifier to be
distributed over the surface of the particles. Once this layer is
applied, the behavior at the interface of the interfacial modifier
to polymer dominates the physical properties of the composite (e.g.
tensile and elongation behavior) while the bulk nature of the
particle dominates the bulk material characteristics of the
composite (e.g. density, thermal conductivity, compressive
strength). The correlation of particulate bulk properties to that
of the final composite is especially strong due to the high volume
percentage loadings of particulate phase associated with the
technology.
[0030] There are two key attributes of the particle surface that
dictate the ability to be successfully interfacially modified: 1)
The overall surface area of the particles on a large scale; large
being defined as about 100.times. or more compared to the molecular
size of the interfacial modifier. In the case of NZ-12, the
molecular diameter is about 2260 pm and 2) Particle surface
characteristics that are on the order of the size of the
interfacial modifier being applied.
[0031] The following particle morphology attributes specifically
contribute to the ability to effectively interfacially modify the
particles. Combining the different particle attributes we have
derived a particle morphology index. Discussion will reveal that
vastly different particle types can be effectively modified from
large, smooth, round, and impervious surface types (low particle
morphology index) to small, rough, irregular and porous (high
particle morphology index):
Particle size (P.sub.S)
[0032] A wide range of particle sizes can be effectively
interfacially modified. Successful modification has been completed
with particles with a major dimension as small as -635 US mesh
(<20 .mu.m) to particles as large as -40 US mesh (-425 .mu.m).
Undoubtedly, larger particle sizes can be effectively modified
(1,500 .mu.m or greater). The absolute size of the particle being
modified is not important; the relative size of the major dimension
of the largest particle to the minimum critical dimension of the
end article is more important. Our composite experience guides us
that the major dimension of the largest particles should not be
more than 1/5.sup.th of the minimum critical dimension of the end
article.
[0033] As the particles become smaller the particulate surface area
increases. For smooth spheres of a constant density, there is 28
times more surface area in spheres of 15 .mu.m than 425 .mu.m
particle size (P.sub.S) within a given mass of material. There is
100 times the surface area for particles of 1,500 .mu.m particle
size (P.sub.S) compared to 15 .mu.m.
[0034] Dosage levels of interfacial modifier have been effectively
adjusted to compensate for changes in surface area due to particle
size shifts.
Particle Shape/Aspect Ratio (P.sub.Sh)
[0035] The benefits of interfacial modification is independent of
overall particle shape. Particles with an aspect ratio of 1 (glass
bubbles of iM30K and ceramic G200 microspheres) to 10 (some
particularly irregularly shaped garnet) have been favorably
interfacially modified. The current upper limit constraint is
associated with challenges of successful dispersion of fibers
within laboratory compounding equipment without significantly
damaging the high aspect ratio fibers. Furthermore, inherent
rheological challenges are associated with high aspect ratio
fibers. With proper engineering, the ability to successfully
compound and produce interfacially modify fibers of fiber fragments
with aspect ratio in excess of 10 is envisioned.
[0036] At a given minor axis particle dimension, the relationship
of particle aspect ratio to surface area is given by:
Sphere=.pi.D.sup.2; and
ARobject=.pi.D.sup.2(r.sub.a+0.5);
wherein D is diameter or particle size (P.sub.S), r.sub.a is aspect
ratio.
[0037] For a given minor dimension, the surface area of a particle
with an aspect ratio of 10 has 10.5 times the surface area than a
spherical particle. Dosage levels of interfacial modifier can be
adjusted to compensate for the variance in surface area due to
shape effects.
Particle Roughness (P.sub.r)
[0038] Macroscopic particle roughness (defined here as 100.times.
the diameter of the interfacial modifier) can be defined by the
circularity of the particle. It has been shown that interfacially
modified mineral or inorganic particulates with rough and
substantially non-spherical shapes obtain the similar advantageous
rheology and physical property results as regularly shaped
particles. The circularity or roughness of the particle can be
measured by microscopic inspection of the particles in which an
automated or manual measurement of roughness can be calculated. In
such a measurement, the perimeter of a representative selection of
the particulate is selected and the area of the particle cross
section is also measured. The circularity of the particle is
calculated by the following formula:
Circularity=(perimeter).sup.2/area.
[0039] Such materials such as the ceramic microspheres and hollow
glass bubbles have a circularity of 4.pi. (for smooth spherical
particles) to 50 (smooth particles with an aspect ratio of 10).
Many inorganic and mineral particulate have an oblong, multi lobe,
rough non-regular shape or aspect. Such materials have a
circularity of 13 to 35 or 13 to 30 and obtain the improved
viscoelastic properties of the invention. Using proper optical and
image analysis techniques the decoupling of surface roughness and
aspect ratio can be determined under the appropriate magnification
to quantify large scale particle roughness. The multiplier for the
derivation of the particle morphology index must be adjusted for
the aspect ratio of the particle.
[0040] An alternative to optical procedures consists of using a BET
analysis to determine the specific surface area of the particulate
phase. The specific surface area captures both the macroscopic
particle roughness and particle porosity discussed below for
particles of a specific particle size and shape distribution.
Particle Porosity (P.sub.p)
[0041] The interfacial modifiers are quite large, on the order of a
few hundred to a few thousand molecular weight. Within a class of
compounds, the effective diameter of the modifier molecule is
proportional to the molecular weight. The predicted diameter of the
NZ-12 zirconate modifier is 2260 picometer with a molecular weight
of 2616 g/mol. The minimum size of the modifier molecules would be
about 400 picometer (assuming a molecular weight of 460 g/mol). The
size of the titanate modifiers would be slightly smaller than the
corresponding zirconate for a corresponding given organophosphate
structure.
[0042] Literature review of BET surface analysis reveals a large
difference in particle surface area of mineral particles (from 0.1
to >100 m.sup.2-gm.sup.-1). Nonporous spheres with a diameter of
1,500 micron results in a specific area of 0.017 m.sup.2-gm.sup.-1.
In all cases, successful interfacial modification of the
particulates is possible via changes in modifier loading. It is
important to note that required increase in dosage is not directly
proportional to the BET surface measurements. The pore size
penetrable by the BET probing gas is significantly smaller (20.5
A.sup.2 for krypton for example) than the interfacial modifier.
Silica sand had a pore size of 0.90 nm as determined by BET
analysis, the interfacial modifier molecule is able to bridge the
pore opening. It will be possible to successfully interfacially
modify porous absorbents such that the particles composite rheology
is improved while absorbent properties of the particulate are
maintained due to the relative size differences in the interfacial
modifier (large), pore size being bridged (small), and the size of
the absorbent molecule (nitrogen, argon, water, etc.) diffusing
through the interfacial modifier into the absorbent
particulate.
[0043] The particle morphology index is defined as:
PMI=(P.sub.S)(P.sub.Sh)(P.sub.r)(P.sub.p)
For large, spherical, smooth, non-porous particles the particle
morphology index=1 to 200. For small, rough, porous particles with
an aspect ratio of 10, the maximum particle morphology
index=100.times.10.5.times.100/0.1=10.sup.6. Certain particles with
a range of sizes or particle size (P.sub.S) and aspect ratios, some
roughness and porosity can range from 200 to 10.sup.4. Other
particles with a broadened range of sizes or particle size
(P.sub.S) and aspect ratios, substantial roughness and increased
porosity can range from 2.times.10.sup.4 to 10.sup.6. The amount of
interfacial modifier increases with the particle morphology
index.
[0044] The result of the above particle attributes (particle size
and distribution, particle shape, and roughness) results in a
specific particle packing behavior. The relationship of these
variables leads to a resultant packing fraction. Packing fraction
is defined as:
P.sub.f=P.sub.d/d.sub.pync
wherein P.sub.f=packing fraction; P.sub.d=packing density and
d.sub.pync=pyncnometer density. The relationship of these variables
upon particle packing behavior is well characterized and used
within powdered metallurgy science. For the case of spherical
particles, it is well known that particle packing increases when
the size difference between large to small particles increases.
With a size ratio of 73 parts by weight large particle: 27 parts by
weight small, monodispersed spheres with a 7:1 size ratio, the
small particles can fit within interstitial spaces of the large
particles resulting in a packing level of about 86 volume percent.
In practice, it is not possible to attain monodispersed spheres. We
have found that increased packing is best when using particles of
broad particle size distribution with as large of a size difference
between them as possible. In cases like these, we have found
packing percentages approaching 80 volume %.
[0045] For composites containing high volumetric loading of
spherical particles, the rheological behavior of the highly packed
composites depends on the characteristics of the contact points
between the particles and the distance between particles. When
forming composites with polymeric volumes approximately equal to
the excluded volume of the particulate phase, inter-particle
interaction dominates the behavior of the material. Particles
contact one another and the combination of interacting sharp edges,
soft surfaces (resulting in gouging) and the friction between the
surfaces prevent further or optimal packing. Interfacial modifying
chemistries are capable of altering the surface of the particulate
by coordination bonding, Van der Waals forces, covalent bonding, or
a combination of all three. The surface of the interfacially
modified particle behaves as a particle of the interfacial
modifier. These organics reduce the friction between particles
preventing gouging and allowing for greater freedom of movement
between particles. The benefits of utilizing particles in the
aforementioned acceptable particle morphology index range does not
become evident until packing to a significant proportion of the
maximum packing fraction; this value is typically greater than
approximately 40 volume % particle phase of the composite.
[0046] The spatial character of the particles of the invention can
be defined by the circularity of the particle and by its aspect
ratio. One surprising aspect of the invention is that even a
particle that depart from smooth spherical particle shape and are
non-spherical or have substantial aspect ratio are efficiently
packed in the composite of the invention. Mineral or inorganic
particulates with amorphous, rough and substantially non-spherical
shapes obtain the same advantageous rheology as regularly shaped
particles. The aspect ratio of the more regular particles of the
invention should be less than 1:5 and often less than 1:1.5.
Similarly, the particulate with an aspect ratio of less than 10 or
about 5:1 also obtain the benefits of the composites of the
invention.
[0047] We have found that the use of the interfacial modifier
disclosed in this application obtains a close association of both
spherical and substantially aspherical particles such that
effective composites can be made even with particles that
substantially depart from the ideal spherical particle. Many
inorganic or mineral particles, depending on source and processing
can have a narrow particle size distribution, a very regular
surface, a low aspect ratio and substantial circularity while other
such particles can have a very amorphous non-regular geometry and
surface characteristic. We have found that the processes of the
invention and the composites made using the interfacial modifier of
the invention can obtain useful composites from most particle
species disclosed herein.
[0048] In the composites of the invention, the van der Waals'
forces occur between collections of inorganic mineral particles
that act as "molecules" in the form of crystals or other mineral
particle aggregates. The composite of the invention is
characterized by a composite having intermolecular forces between
inorganic mineral particulates that are in the range of van der
Waals' strength, i.e., ranges and definitions if appropriate.
[0049] In a composite, the inorganic mineral particle is usually
much stronger and stiffer than the matrix, and gives the composite
its designed properties. The matrix holds the inorganic mineral
particle s in an orderly high-density pattern. Because the
inorganic mineral particles are usually discontinuous, the matrix
also helps to transfer load among the inorganic mineral particles.
Processing can aid in the mixing and filling of the inorganic
mineral particle. To aid in the mixture, an interfacial modifier, a
surface chemical treatment or modifier can help to overcome the
forces that prevent the matrix from forming a substantially
continuous phase of the composite. The tunable composite properties
arise from the intimate association obtained by use of careful
processing and manufacture. We believe a surface chemical reagent
is an organic material that provides an exterior coating on the
particulate promoting the close association of polymer and
particulate. Minimal amounts of the interfacial modifier can be
used including about 0.005 to 8 wt.-%, or about 0.02 to 3 wt. %.
Higher amounts are used to coat materials with increased
morphology.
[0050] Examples of minerals that are useful to the invention
include Carbides, Nitrides, Silicides and Phosphides; Sulphides,
Selenides, Tellurides, Arsenides and Bismuthides; Oxysulphides;
Sulphosalts, such as Sulpharsenites, Sulphobismuthites,
Sulphostannates, Sulphogermanates, Sulpharsenates,
Sulphantimonates, Sulphovanadates and Sulphohalides; Oxides and
Hydroxides; Halides, such as Fluorides, Chlorides, Bromides and
Iodides; Fluoborates and Fluosilicates; Borates; Carbonates;
Nitrates; Silicates; Silicates of Aluminum; Silicates Containing
Aluminum and other Metals; Silicates Containing other Anions;
Niobates and Tantalates; Phosphates; Arsenates such as arsenates
with phosphate (without other anions); Vanadates (vanadates with
arsenate or phosphate); Phosphates, Arsenates or Vanadates;
Arsenites; Antimonates and Antimonites; Sulphates; Sulphates with
Halide; Sulphites, Chromates, Molybdates and Tungstates; Selenites,
Selenates, Tellurites, and Tellurates; Iodates; Thiocyanates;
Oxalates, Citrates, Mellitates and Acetates include the arsenides,
antimonides and bismuthides of e.g., metals such as Li, Na, Ca, Ba,
Mg, Mn, Al, Ni, Zn, Ti, Fe, Cu, Ag and Au.
[0051] Garnet, is an important mineral and is a nesosilicate that
complies with general formula X.sub.3Y.sub.2(SiO.sub.4).sub.3. The
X is divalent cation, typically Ca.sup.2+, Mg.sup.2+, Fe.sup.2+
etc. and the Y is trivalent cation, typically Al.sup.3+, Fe.sup.3+,
Cr.sup.3+, etc. in an octahedral/tetrahedral framework with
[SiO.sub.4].sup.4- occupying the tetrahedra. Garnets are most often
found in the dodecahedral form, less often in trapezo-hedral
form.
[0052] One important inorganic material that can be used as a
particulate in the invention includes silica, silicon dioxide
(SiO.sub.2). Silica is commonly found as sand or as quartz
crystalline materials. Also, silica is the major component of the
cell walls of diatoms commonly obtained as diatomaceous earth.
Silica in the form of fused silica or glass has fused silica or
silica line-glass as fumed silica, as diatomaceous earth or other
forms of silica as a material density of about 2.7 gm-cm.sup.-3 but
a particulate density that ranges from about 1.5 to 2
gm-cm.sup.-3.
[0053] Typically, the composite materials of the invention are
manufactured using melt processing and are also utilized in product
formation using melt processing. A typical thermoplastic polymer
material, is combined with particulate and processed until the
material attains (e.g.) a uniform density (if density is the
characteristic used as a determinant). Alternatively, in the
manufacture of the material, the inorganic mineral or the
thermoplastic polymer may be blended with interfacial modification
agents and the modified materials can then be melt processed into
the material. Once the material attains a sufficient property, such
as, for example, density, the material can be extruded into a
product or into a raw material in the form of a pellet, chip,
wafer, proform or other easily processed material using
conventional processing techniques.
[0054] In the manufacture of useful products with the composites of
the invention, the manufactured composite can be obtained in
appropriate amounts, subjected to heat and pressure, typically in
extruder equipment and then formed into an appropriate shape having
the correct amount of materials in the appropriate physical
configuration. In the appropriate product design, during composite
manufacture or during product manufacture, a pigment or other dye
material can be added to the processing equipment. One advantage of
this material is that an inorganic dye or pigment can be
co-processed resulting in a material that needs no exterior
painting or coating to obtain an attractive, functional, or
decorative appearance. The pigments can be included in the polymer
blend, can be uniformly distributed throughout the material and can
result in a surface that cannot chip, scar or lose its decorative
appearance. One particularly important pigment material comprises
titanium dioxide (TiO.sub.2). This material is extremely non-toxic,
is a bright white particulate that can be easily combined with
either inorganic mineral particulates or polymer composites to
enhance the novel characteristics of the composite material and to
provide a white hue to the ultimate composite material.
[0055] We have further found that a blend of two, three or more
inorganic minerals in particulate form can, obtain important
composite properties from all of particulate materials in a polymer
composite structure. Such composites each can have unique or
special properties. These composite processes and materials have
the unique capacity and property that the composite acts as an
blended composite of two or three different inorganic minerals that
could not, due to melting point and other processing difficulties,
be made into a blend without the methods of the invention.
[0056] A large variety of polymer materials can be used in the
composite materials of the invention. For the purpose of this
application, a polymer is a general term covering either a
thermoset or a thermoplastic. We have found that polymer materials
useful in the invention include both condensation polymeric
materials and addition or vinyl polymeric materials. Included are
both vinyl and condensation polymers, and polymeric alloys thereof.
Vinyl polymers are typically manufactured by the polymerization of
monomers having an ethylenically unsaturated olefinic group.
Condensation polymers are typically prepared by a condensation
polymerization reaction which is typically considered to be a
stepwise chemical reaction in which two or more molecules combined,
often but not necessarily accompanied by the separation of water or
some other simple, typically volatile substance. Such polymers can
be formed in a process called polycondensation. The polymer has a
density of at least 0.85 gm-cm.sup.-3, however, polymers having a
density of greater than 0.96 are useful to enhance overall product
density. A density is often up to 1.7 or up to 2 gm-cm.sup.-3 or
can be about 1.5 to 1.95 gm-cm.sup.-3.
[0057] Vinyl polymers include polyethylene, polypropylene,
polybutylene, acrylonitrile-butadiene-styrene (ABS), polybutylene
copolymers, polyacetyl resins, polyacrylic resins, homopolymers or
copolymers comprising vinyl chloride, vinylidene chloride,
fluorocarbon copolymers, etc. Condensation polymers include nylon,
phenoxy resins, polyarylether such as polyphenylether,
polyphenylsulfide materials; polycarbonate materials, chlorinated
polyether resins, polyethersulfone resins, polyphenylene oxide
resins, polysulfone resins, polyimide resins, thermoplastic
urethane elastomers and many other resin materials.
[0058] Condensation polymers that can be used in the composite
materials of the invention include polyamides, polyamide-imide
polymers, polyarylsulfones, polycarbonate, polybutylene
terephthalate, polybutylene naphthalate, polyetherimides,
polyethersulfones, polyethylene terephthalate, thermoplastic
polyamides, polyphenylene ether blends, polyphenylene sulfide,
polysulfones, thermoplastic polyurethanes and others. Preferred
condensation engineering polymers include polycarbonate materials,
polyphenyleneoxide materials, and polyester materials including
polyethylene terephthalate, polybutylene terephthalate,
polyethylene naphthalate and polybutylene naphthalate
materials.
[0059] Polycarbonate engineering polymers are high performance,
amorphous engineering thermoplastics having high impact strength,
clarity, heat resistance and dimensional stability. Polycarbonates
are generally classified as a polyester or carbonic acid with
organic hydroxy compounds. The most common polycarbonates are based
on phenol A as a hydroxyl compound copolymerized with carbonic
acid. Materials are often made by the reaction of a biphenyl A with
phosgene (O.dbd.CCl.sub.2). Polycarbonates can be made with
phthalate monomers introduced into the polymerization extruder to
improve properties such as heat resistance, further trifunctional
materials can also be used to increase melt strength or extrusion
blow molded materials. Polycarbonates can often be used as a
versatile blending material as a component with other commercial
polymers in the manufacture of alloys. Polycarbonates can be
combined with polyethylene terephthalate
acrylonitrile-butadiene-styrene, styrene maleic anhydride and
others. Preferred alloys comprise a styrene copolymer and a
polycarbonate. Preferred polycarbonate materials should have a melt
index between 0.5 and 7, preferably between 1 and 5 gms/10 min.
[0060] A variety of polyester condensation polymer materials
including polyethylene terephthalate, polybutylene terephthalate,
polyethylene naphthalate, polybutylene naphthalate, etc. can be
useful in the composites of the invention. Polyethylene
terephthalate and polybutylene terephthalate are high performance
condensation polymer materials. Such polymers often made by a
copolymerization between a diol (ethylene glycol, 1,4-butane diol)
with dimethyl terephthalate. In the polymerization of the material,
the polymerization mixture is heated to high temperature resulting
in the transesterification reaction releasing methanol and
resulting in the formation of the engineering plastic. Similarly,
polyethylene naphthalate and polybutylene naphthalate materials can
be made by copolymerizing as above using as an acid source, a
naphthalene dicarboxylic acid. The naphthalate thermoplastics have
a higher Tg and higher stability at high temperature compared to
the terephthalate materials. However, all these polyester materials
are useful in the composite materials of the invention. Such
materials have a preferred molecular weight characterized by melt
flow properties. Useful polyester materials have a viscosity at
265.degree. C. of about 500-2000 cP, preferably about 800-1300
cP.
[0061] Polyphenylene oxide materials are engineering thermoplastics
that are useful at temperature ranges as high as 330.degree. C.
Polyphenylene oxide has excellent mechanical properties,
dimensional stability, and dielectric characteristics. Commonly,
phenylene oxides are manufactured and sold as polymer alloys or
blends when combined with other polymers or fiber. Polyphenylene
oxide typically comprises a homopolymer of 2,6-dimethyl-1-phenol.
The polymer commonly known as
poly(oxy-(2,6-dimethyl-1,4-phenylene)). Polyphenylene is often used
as an alloy or blend with a polyamide, typically nylon 6-6, alloys
with polystyrene or high impact styrene and others. A preferred
melt index (ASTM 1238) for the polyphenylene oxide material useful
in the invention typically ranges from about 1 to 20, preferably
about 5 to 10 gm/10 min. The melt viscosity is about 1000 cP at
265.degree. C.
[0062] Another class of thermoplastic include styrenic copolymers.
The term styrenic copolymer indicates that styrene is copolymerized
with a second vinyl monomer resulting in a vinyl polymer. Such
materials contain at least a 5 mol-% styrene and the balance being
1 or more other vinyl monomers. An important class of these
materials are styrene acrylonitrile (SAN) polymers. SAN polymers
are random amorphous linear copolymers produced by copolymerizing
styrene acrylonitrile and optionally other monomers. Emulsion,
suspension and continuous mass polymerization techniques have been
used. SAN copolymers possess transparency, excellent thermal
properties, good chemical resistance and hardness. These polymers
are also characterized by their rigidity, dimensional stability and
load bearing capability. Olefin modified SAN's (OSA polymer
materials) and acrylic styrene acrylonitriles (ASA polymer
materials) are known. These materials are somewhat softer than
unmodified SAN's and are ductile, opaque, two phased terpolymers
that have surprisingly improved weatherability.
[0063] ASA polymers are random amorphous terpolymers produced
either by mass copolymerization or by graft copolymerization. In
mass copolymerization, an acrylic monomer styrene and acrylonitrile
are combined to form a heteric terpolymer. In an alternative
preparation technique, styrene acrylonitrile oligomers and monomers
can be grafted to an acrylic elastomer backbone. Such materials are
characterized as outdoor weatherable and UV resistant products that
provide excellent accommodation of color stability property
retention and property stability with exterior exposure. These
materials can also be blended or alloyed with a variety of other
polymers including polyvinyl chloride, polycarbonate, polymethyl
methacrylate and others. An important class of styrene copolymers
includes the acrylonitrile-butadiene-styrene monomers. These
polymers are very versatile family of engineering thermoplastics
produced by copolymerizing the three monomers. Each monomer
provides an important property to the final terpolymer material.
The final material has excellent heat resistance, chemical
resistance and surface hardness combined with processability,
rigidity and strength. The polymers are also tough and impact
resistant. The styrene copolymer family of polymers have a melt
index that ranges from about 0.5 to 25, preferably about 0.5 to
20.
[0064] An important class of engineering polymers that can be used
in the composites of the invention include acrylic polymers.
Acrylics comprise a broad array of polymers and copolymers in which
the major monomeric constituents are an ester acrylate or
methacrylate. These polymers are often provided in the form of
hard, clear sheet or pellets. Acrylic monomers polymerized by free
radical processes initiated by typically peroxides, azo compounds
or radiant energy. Commercial polymer formulations are often
provided in which a variety of additives are modifiers used during
the polymerization provide a specific set of properties for certain
applications. Pellets made for polymer grade applications are
typically made either in bulk (continuous solution polymerization),
followed by extrusion and pelleting or continuously by
polymerization in an extruder in which unconverted monomer is
removed under reduced pressure and recovered for recycling. Acrylic
plastics are commonly made by using methyl acrylate,
methylmethacrylate, higher alkyl acrylates and other
copolymerizable vinyl monomers. Preferred acrylic polymer materials
useful in the composites of the invention has a melt index of about
0.5 to 50, preferably about 1 to 30 gm/10 min.
[0065] Vinyl polymer polymers include a acrylonitrile; polymer of
alpha-olefins such as ethylene, propylene, etc.; chlorinated
monomers such as vinyl chloride, vinylidene dichloride, acrylate
monomers such as acrylic acid, methylacrylate, methylmethacrylate,
acrylamide, hydroxyethyl acrylate, and others; styrenic monomers
such as styrene, alphamethyl styrene, vinyl toluene, etc.; vinyl
acetate; and other commonly available ethylenically unsaturated
monomer compositions.
[0066] Polymer blends or polymer alloys can be useful in
manufacturing the pellet or linear extrudate of the invention. Such
alloys typically comprise two miscible polymers blended to form a
uniform composition. Scientific and commercial progress in the area
of polymer blends has lead to the realization that important
physical property improvements can be made not by developing new
polymer material but by forming miscible polymer blends or alloys.
A polymer alloy at equilibrium comprises a mixture of two amorphous
polymers existing as a single phase of intimately mixed segments of
the two macro molecular components. Miscible amorphous polymers
form glasses upon sufficient cooling and a homogeneous or miscible
polymer blend exhibits a single, composition dependent glass
transition temperature (Tg). Immiscible or non-alloyed blend of
polymers typically displays two or more glass transition
temperatures associated with immiscible polymer phases. In the
simplest cases, the properties of polymer alloys reflect a
composition weighted average of properties possessed by the
components. In general, however, the property dependence on
composition varies in a complex way with a particular property, the
nature of the components (glassy, rubbery or semi-crystalline), the
thermodynamic state of the blend, and its mechanical state whether
molecules and phases are oriented.
[0067] The primary requirement for the substantially thermoplastic
engineering polymer material is that it retains sufficient
thermoplastic properties such as viscosity and stability, to permit
melt blending with a particulate, permit formation of linear
extrudate pellets, and to permit the composition material or pellet
to be extruded or injection molded in a thermoplastic process
forming the useful product. Engineering polymer and polymer alloys
are available from a number of manufacturers including Dyneon LLC,
B.F. Goodrich, G. E., Dow, and duPont.
[0068] Polyester polymers are manufactured by the reaction of a
dibasic acid with a glycol. Dibasic acids used in polyester
production include phthalic anhydride, isophthalic acid, maleic
acid and adipic acid. The phthalic acid provides stiffness,
hardness and temperature resistance; maleic acid provides vinyl
saturation to accommodate free radical cure; and adipic acid
provides flexibility and ductility to the cured polymer. Commonly
used glycols are propylene glycol which reduces crystalline
tendencies and improves solubility in styrene. Ethylene glycol and
diethylene glycol reduce crystallization tendencies. The diacids
and glycols are condensed eliminating water and are then dissolved
in a vinyl monomer to a suitable viscosity. Vinyl monomers include
styrene, vinyltoluene, paramethylstyrene, methylmethacrylate, and
diallyl phthalate. The addition of a polymerization initiator, such
as hydroquinone, tertiary butylcatechol or phenothiazine extends
the shelf life of the uncured polyester polymer. Polymers based on
phthalic anhydride are termed orthophthalic polyesters and polymers
based on isophthalic acid are termed isophthalic polyesters. The
viscosity of the unsaturated polyester polymer can be tailored to
an application. Low viscosity is important in the fabrication of
fiber-reinforced composites to ensure good wetting and subsequent
high adhesion of the reinforcing layer to the underlying substrate.
Poor wetting can result in large losses of mechanical properties.
Typically, polyesters are manufactured with a styrene concentration
or other monomer concentration producing polymer having an uncured
viscosity of 200-1,000 mPas(cP). Specialty polymers may have a
viscosity that ranges from about 20 cP to 2,000 cP. Unsaturated
polyester polymers are typically cured by free radical initiators
commonly produced using peroxide materials. Wide varieties of
peroxide initiators are available and are commonly used. The
peroxide initiators thermally decompose forming free radical
initiating species.
[0069] Phenolic polymers can also be used in the manufacture of the
structural members of the invention. Phenolic polymers typically
comprise a phenol-formaldehyde polymer. Such polymers are
inherently fire resistant, heat resistant and are low in cost.
Phenolic polymers are typically formulated by blending phenol and
less than a stoichiometric amount of formaldehyde. These materials
are condensed with an acid catalyst resulting in a thermoplastic
intermediate polymer called NOVOLAK. These polymers are oligomeric
species terminated by phenolic groups. In the presence of a curing
agent and optional heat, the oligomeric species cure to form a very
high molecular weight thermoset polymer. Curing agents for novalaks
are typically aldehyde compounds or methylene (--CH.sub.2--)
donors. Aldehydic curing agents include paraformaldehyde,
hexamethylenetetramine, formaldehyde, propionaldehyde, glyoxal and
hexamethylmethoxy melamine.
[0070] The fluorocarbon polymers useful in this invention are
perflourinated and partially fluorinated polymers made with
monomers containing one or more atoms of fluorine, or copolymers of
two or more of such monomers. Common examples of fluorinated
monomers useful in these polymers or copolymers include
tetrafluoroethylene (TFE), hexafluoropropylene(HFP), vinylidene
fluoride (VDF), perfluoroalkylvinyl ethers such as
perfluoro-(n-propyl-vinyl)ether (PPVE) or perfluoromethylvinylether
(PMVE). Other copolymerizable olefinic monomers, including
non-fluorinated monomers, may also be present.
[0071] Particularly useful materials for the fluorocarbon polymers
are TFE-HFP-VDF terpolymers (melting temperature of about 100 to
260.degree. C.; melt flow index at 265.degree. C. under a 5 kg load
is about 1-30 g-10 min.sup.-1.),
hexafluoropropylene-tetrafluoroethylene-ethylene (HTE) terpolymers
(melting temperature about 150 to 280.degree. C.; melt flow index
at 297.degree. C. under a 5 kg load of about 1-30 g-10 min.sup.-1),
ethylene-tetrafluoroethylene (ETFE) copolymers (melting temperature
about 250 to 275.degree. C.; melt flow index at 297.degree. C.
under a 5 kg load of about 1-30 g-10 min.sup.-1.),
hexafluoropropylene-tetrafluoroethylene (FEP) copolymers (melting
temperature about 250 to 275.degree. C.; melt flow index at
372.degree. C. under a 5 kg load of about 1-30 g-10 min.sup.-1.),
and tetrafluoroethylene-perfluoro(alkoxy alkane) (PFA) copolymers
(melting temperature about 300 to 320.degree. C.; melt flow index
at 372.degree. C. under a 5 kg load of about 1-30 g-10
min.sup.-1.). Each of these fluoropolymers is commercially
available from Dyneon LLC, Oakdale, Minn. The TFE-HFP-VDF
terpolymers are sold under the designation "THV".
[0072] Also useful are vinylidene fluoride polymers primarily made
up of monomers of vinylidene fluoride, including both homo polymers
and copolymers. Such copolymers include those containing at least
50 mole percent of vinylidene fluoride copolymerized with at least
one comonomer selected from the group consisting of
tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene,
hexafluoropropene, vinyl fluoride, pentafluoropropene, and any
other monomer that readily copolymerizes with vinylidene fluoride.
These materials are further described in U.S. Pat. No. 4,569,978
(Barber) incorporated herein by reference. Preferred copolymers are
those composed of from at least about 70 and up to 99 mole percent
vinylidene fluoride, and correspondingly from about 1 to 30 percent
tetrafluoroethylene, such as disclosed in British Patent No.
827,308; and about 70 to 99 percent vinylidene fluoride and 1 to 30
percent hexafluoropropene (see for example U.S. Pat. No.
3,178,399); and about 70 to 99 mole percent vinylidene fluoride and
1 to 30 percent trifluoroethylene. Terpolymers of vinylidene
fluoride, trifluoroethylene and tetrafluoroethylene such as
described in U.S. Pat. No. 2,968,649 and terpolymers of vinylidene
fluoride, trifluoroethylene and tetrafluoroethylene are also
representative of the class of vinylidene fluoride copolymers which
are useful in this invention. Such materials are commercially
available under the KYNAR trademark from Arkema Group located in
King of Prussia, Pa. or under the DYNEON trademark from Dyneon LLC
of Oakdale, Minn.
[0073] Fluorocarbon elastomer materials can also be used in the
composite materials of the invention. Fluorocarbon elastomers
contain VF.sub.2 and HFP monomers and optionally TFE and have a
density greater than 1.8 gm-cm.sup.-3; these polymers exhibit good
resistance to most oils, chemicals, solvents, and halogenated
hydrocarbons, and excellent resistance to ozone, oxygen, and
weathering. Their useful application temperature range is
-40.degree. C. to 300.degree. C. Fluorocarbon elastomer examples
include those described in detail in Lentz, U.S. Pat. No.
4,257,699, as well as those described in Eddy et al., U.S. Pat. No.
5,017,432 and Ferguson et al., U.S. Pat. No. 5,061,965. The
disclosures of each of these patents are totally incorporated
herein by reference.
[0074] Latex fluorocarbon polymers are available in the form of the
polymers comprising the PFA, FEP, ETFE, HTE, THV and PVDF monomers.
Fluorinated poly(meth)acrylates can generally be prepared by free
radical polymerization either neat or in solvent, using radical
initiators well known to those skilled in the art. Other monomers
which can be copolymerized with these fluorinated (meth)acrylate
monomers include alkyl (meth)acrylates, substituted alkyl
(meth)acrylates, (meth)acrylic acid, (meth)acrylamides, styrenes,
vinyl halides, and vinyl esters. The fluorocarbon polymers can
comprise polar constituents. Such polar groups or polar group
containing monomers may be anionic, nonionic, cationic, or
amphoteric. In general, the more commonly employed polar groups or
polar group-containing organic radicals include organic acids,
particularly carboxylic acid, sulfonic acid and phosphonic acid;
carboxylate salts, sulfonates, phosphonates, phosphate esters,
ammonium salts, amines, amides, alkyl amides, alkyl aryl amides,
imides, sulfonamides, hydroxymethyl, thiols, esters, silanes, and
polyoxyalkylenes, as well as other organic radicals such as
alkylene or arylene substituted with one or more of such polar
groups. The latex fluorocarbon polymers described herein are
typically aqueous dispersed solids but solvent materials can be
used. The fluorocarbon polymer can combined with various solvents
to form emulsion, solution or dispersion in a liquid form.
Dispersions of fluoropolymers can be prepared using conventional
emulsion polymerization techniques, such as described in U.S. Pat.
Nos. 4,418,186; 5,214,106; 5,639,838; 5,696,216 or Modern
Fluoropolymers, Edited by John Scheirs, 1997 (particularly pp.
71-101 and 597-614) as well as assignees' co-pending patent
application Ser. No. 1/03195, filed Jan. 31, 2001.
[0075] The liquid forms can be further diluted in order to deliver
the desired concentration. Although aqueous emulsions, solutions,
and dispersions are preferred, up to about 50% of a cosolvent such
as methanol, isopropanol, or methyl perfluorobutyl ether may be
added. Preferably, the aqueous emulsions, solutions, and
dispersions comprise less than about 30% cosolvent, more preferably
less than about 10% cosolvent, and most preferably the aqueous
emulsions, solutions, and dispersions are substantially free of
cosolvent.
[0076] Interfacial modifiers provide the close association of the
particle with the polymer. Interfacial modifiers used in the
non-reactive or non-crosslinking application fall into broad
categories including, for example, stearic acid derivatives,
titanate compounds, zirconate compounds, phosphonate compounds,
aluminate compounds. Aluminates, phosphonates, titanates and
zirconates useful contain from about 1 to about 3 ligands
comprising hydrocarbyl phosphate esters and/or hydrocarbyl
sulfonate esters and about 1 to 3 hydrocarbyl ligands which may
further contain unsaturation and heteroatoms such as oxygen,
nitrogen and sulfur. Preferably the titanates and zirconates
contain from about 2 to about 3 ligands comprising hydrocarbyl
phosphate esters and/or hydrocarbyl sulfonate esters, preferably 3
of such ligands and about 1 to 2 hydrocarbyl ligands, preferably 1
hydrocarbyl ligand.
[0077] The choice of interfacial modifiers is dictated by
particulate, polymer, and application. The particle surface is
substantially coated even if having substantial morphology. The
coating isolates the polymer form the particle. The maximum density
of a composite is a function of the densities of the materials and
the volume fractions of each. Higher density composites are
achieved by maximizing the per unit volume of the materials with
the highest densities. The inorganic materials are extremely hard
and difficult to deform, usually resulting in brittle fracture.
When compounded with deformable polymeric binders, these brittle
materials may be formed into usable shapes using traditional
thermoplastic equipment. However, the maximum densities achievable
will be less then optimum. When forming composites with polymeric
volumes approximately equal to the excluded volume of the filler,
inter-particle interaction dominates the behavior of the material.
Particles contact one another and the combination of interacting
sharp edges, soft surfaces (resulting in gouging, points are
usually work hardened) and the friction between the surfaces
prevent further or optimal packing Therefore, maximizing properties
is a function of softness of surface, hardness of edges, point size
of point (sharpness), surface friction force and pressure on the
material, circularity, and the usual, shape size distribution.
Because of this inter-particle friction, the forming pressure will
decrease exponentially with distance from the applied force.
Interfacially modifying chemistries are capable of modifying the
surface of the dense filler by coordination bonding, Van der Waals
forces, covalent bonding, or a combination of all three. The
surface of the particle behaves as a particle the interfacial
modifier. These organics reduce the friction between particles
preventing gouging and allowing for greater freedom of movement
between particles. These phenomenon allow the applied shaping force
to reach deeper into the form resulting in a more uniform pressure
gradient.
[0078] Preferred titanates and zirconates include isopropyl
tri(dioctyl)pyrophosphato titanate (available from Kenrich
Chemicals under the designation KR38S), Commercial titanates
Kr-238J and KR-9S, neopentyl(diallyl)oxy,
tri(dodecyl)benzene-sulfonyl titanate (available from Kenrich
Chemicals under the trademark and designation LICA 09),
neopentyl(diallyl)oxy, trioctylphosphato titanate (available from
Kenrich Chemicals under the trademark and designation LICA 12),
neopentyl(diallyl)oxy, tri(dodecyl)benzene-sulfonyl zirconate
(available from Kenrich Chemicals under the designation NZ 09),
neopentyl(diallyl)oxy, tri(dioctyl)phosphato zirconate (available
from Kenrich Chemicals under the designation NZ 12), and
neopentyl(diallyl)oxy, tri(dioctyl)pyro-phosphato zirconate
(available from Kenrich Chemicals under the designation NZ 38). The
most preferred titanate is tri(dodecyl)benzene-sulfonyl titanate
(available from Kenrich Chemicals under the designation LICA 09).
The interfacial modifiers modify the particulate in the composites
of the invention with the formation of a layer on the surface of
the particle reducing the intermolecular forces, improving the
tendency of the polymer mix with the particle, and resulting in
increased composite density. Density is maximized as the number of
claose association between the particulate surface and polymer is
maximized.
[0079] Thermosetting polymers can be used in an uncured form to
make the composites with the interfacial modifiers. Once the
composite is formed the reactive materials can chemically bond the
polymer phase if a thermoset polymer is selected. The reactive
groups in the thermoset can include methacrylyl, styryl, or other
unsaturated or organic materials.
[0080] Thermoplastics include polyvinylchloride, polyphenylene
sulfite, acrylic homopolymers, maleic anhydride containing
polymers, acrylic materials, vinyl acetate polymers, diene
containing copolymers such as 1,3-butadiene, 1,4-pentadiene,
halogen or chlorosulfonyl modified polymers or other polymers that
can react with the composite systems of the invention. Condensation
polymeric thermoplastics can be used including polyamides,
polyesters, polycarbonates, polysulfones and similar polymer
materials by reacting end groups with silanes having aminoalkyl,
chloroalkyl, isocyanato or similar functional groups.
[0081] The manufacture of the particulate composite materials
depends on good manufacturing technique. Often the particulate is
initially treated with an interfacial modifier by spraying the
particulate with a 25 wt-% solution of interfacial modifier on the
particle with blending and drying carefully to ensure uniform
particulate coating. interfacial modifier can also be added to
particles in bulk blending operations using high intensity
Littleford or Henschel blenders. Alternatively, twin cone mixers
can be followed by drying or direct addition to a screw compounding
device. Interfacial modifiers may also be combined with the
particulate in aprotic solvent such as toluene, tetrahydrofuran,
mineral spirits or other such known solvents.
[0082] The particulate can be interfacially combined into the
polymer phase depending on the nature of the polymer phase, the
filler, the particulate surface chemistry and any pigment process
aid or additive present in the composite material. In general, the
mechanism used to couple particulate to polymer include solvation,
chelation, coordination bonding (ligand formation), etc. Typically,
however, covalent bonds, linking the particle or interfacial
modifier, and the polymer is not formed. Titanate, phosphonate or
zirconate agents can be used. Such agents have the following
formula:
(RO).sub.m-Ti-(O-X-R'-Y).sub.n
(RO).sub.m-Zr-(O-X-R'-Y).sub.n
(RO).sub.m-P-(O-X-R'-Y).sub.n
wherein R and R' are independanly a hydrocarbyl, C.sub.1-12 alkyl
group or a C.sub.7-20 alkyl or alkaryl group wherein the alkyl or
alkaryl groups may optionally contain one or more oxygen atoms or
unsaturation; X is sulfate or phosphate; Y is H or any common
substituent for alkyl or aryl groups; m and n are 1 to 3. Titanates
provide antioxidant properties and can modify or control cure
chemistry. Zirconate provides excellent bond strength but maximizes
curing, reduces formation of off color in formulated thermoplastic
materials. A useful zirconate material is neopentyl(diallyl)
oxy-tri (dioctyl) phosphato-zirconate.
[0083] The composite materials having the desired physical
properties can be manufactured as follows. In a preferred mode, the
surface coating of the particulate is initially prepared. The
interfacial modifier is combined with the prepared particle
material, and the resulting product is isolated and then combined
with the continuous polymer phase to affect an interfacial
association between the particulate and the polymer. In the
composite the coating is less than 1 microns thick and isolates the
polymer form the particle. The polymer "sees" only the coating.
Once the composite material is prepared, it is then formed into the
desired shape of the end use material. Solution processing is an
alternative that provides solvent recovery during materials
processing. The materials can also be dry-blended without solvent.
Blending systems such as ribbon blenders obtained from Drais
Systems, high density drive blenders available from Littleford
Brothers and Henschel are possible. Further melt blending using
Banberry, veferralle single screw or twin screw compounders is also
useful. When the materials are processed as a plastisol or
organosol with solvent, liquid ingredients are generally charged to
a processing unit first, followed by polymer polymer, particulate
and rapid agitation. Once all materials are added a vacuum can be
applied to remove residual air and solvent, and mixing is continued
until the product is uniform and high in density.
[0084] Dry blending is generally preferred due to advantages in
cost. However certain embodiments can be compositionally unstable
due to differences in particle size. In dry blending processes, the
composite can be made by first introducing the polymer, combining
the polymer stabilizers, if necessary, at a temperature from about
ambient to about 60.degree. C. with the polymer, blending a
particulate (modified if necessary) with the stabilized polymer,
blending other process aids, interfacial modifier, colorants,
indicators or lubricants followed by mixing in hot mix, transfer to
storage, packaging or end use manufacture.
[0085] Interfacially modified materials can be made with solvent
techniques that use an effective amount of solvent to initiate
formation of a composite. When interfacial treatment is
substantially complete, the solvent can be stripped. Such solvent
processes are conducted as follows: [0086] 1) Solvating the
interfacial modifier or polymer or both; [0087] 2) Mixing the
particulate into a bulk phase or polymer master batch: and [0088]
3) Devolatilizing the composition in the presence of heat and
vacuum above the Tg of the polymer.
[0089] When compounding with twin screw compounders or extruders, a
preferred process can be used involving twin screw compounding as
follows. [0090] 1. Add particulate and raise temperature to remove
surface water (barrel 1). [0091] 2. Add interfacial modifier to
twin screw when filler is at temperature (barrel 3). [0092] 3.
Disperse/distribute surface chemical treatment on particulate.
[0093] 4. Maintain temperature to completion. [0094] 5. Vent
by-products (barrel 6). [0095] 6. Add polymer binder (barrel 7).
[0096] 7. Compress/melt polymer binder. [0097] 8.
Disperse/distribute polymer binder in particulate. [0098] 9. Form
surface modified particulate with polymer binder. [0099] 10. Vacuum
degas remaining products (barrel 9). [0100] 11. Compress resulting
composite. [0101] 12. Form desired shape, pellet, lineal, tube,
injection mold article, etc. through a die or post-manufacturing
step.
[0102] Alternatively in formulations containing small volumes of
continuous phase: [0103] 1. Add polymer binder. [0104] 2. Add
interfacial modifier to twin screw when polymer binder is at
temperature. [0105] 3. Disperse/distribute interfacial modifier in
polymer binder. [0106] 4. Add filler and disperse/distribute
particulate. [0107] 5. Raise temperature to effective coating
temperature. [0108] 6. Maintain temperature to completion. [0109]
7. Compress resulting composite. [0110] 8. Form desired shape,
pellet, lineal, tube, injection mold article, etc. through a die or
post-manufacturing step.
[0111] Certain selections of polymers and particulates may permit
the omission of the interfacial modifier and their related
processing steps.
Experimental Section
[0112] THV220A (Dyneon Polymers, Oakdale Minn.) is a polymer of
tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride.
The material is intended for extrusion applications, has a melting
point of 120.degree. C. and a specific gravity of 1.9 g/cc.
[0113] NZ 12 is
neopentyl(diallyl)oxy-tri(dioctyl)phosphato-zirconate. It is
available from KenRich Petrochemicals (Bayonne, N.J.). NZ12 has a
specific gravity of 1.06 g/cc and is readily soluble in isopropyl
alcohol (IPA).
Methods and Procedures
Powder Characterizations:
[0114] Powder characterization is completed to determine packing
behavior of the powdered materials. Packing fraction is determined
by dividing the packing density of the powder by the true density
as determined via helium pycnometry. Packing fraction is defined
as:
P.sub.f=P.sub.d/d.sub.pync
wherein P.sub.f=packing fraction; P.sub.d=packing density and
d.sub.pync=pyncnometer density.
[0115] Packing density is determined by measuring the bulk powder
weight within a volume. The packing density is commonly determined
by placing the powder within a metallurgical press. The press setup
is available from Buehler International (Lake Bluff, Ill.). For
frangible materials, pressure is reduced to the appropriate level
to reduce breakage of the powder particles thereby preventing
artificially high packing density values. For very frangible
materials, a tap density is used. The pycnometer density is
determined by helium gas pycnometry (AccuPync 1330 manufactured by
Micromeretics Corporation-Norcross, Ga.).
Application of Interfacial Modifier:
[0116] To interfacially modifiy particles at a lab scale, the
interfacial modifier is first soluabilized with IPA. The
IPA/modifier mixture is applied to the powdered material previously
placed within a rotating stainless steel rotating cooking stock
pot. The 3 gallon stainless steel cooking pot was coupled to a DC
drive and motor for controlled rotation with the pot orientated at
30 degrees from horizontal. The IPA/modifier mixture is added along
with additional IPA in enough volume to fully wet and flood the
particles. The outer part of the pot is then heated externally with
an industrial heat gun to volatize the IPA. After a sufficient
time, the modified particles become free flowing--an indication
that they are ready for compounding within our laboratory twin
screw compounding equipment.
Compounding:
[0117] The polymer and modified particles are fed in appropriate
ratios using K-tron K20 gravimetric weight loss feeders. The raw
ingredients are fused together within a 19 mm B&P twin screw
compounder. Barrel zone temperatures (5), screw speed, volumetric
throughput, and die characteristics (number of openings and opening
diameter) are varied depending on the nature of the particles and
polymers being compounded. Commonly, torque, pressure, and melt
temperature are monitored responses. A useful way to ensure the
proper ratio of polymer and particulate(s) is to place compounded
pellets into the heated metallurgical press; we call this the "puck
density".
Extrusion:
[0118] The compounded products are extruded using 1'' diameter
extruder (Al--Be Industries, Fullerton, Calif.). Temperatures and
volumetric throughput vary depending on the rheological behavior of
the materials being extruded. Typically, motor amp load and
extrusion pressures are monitored responses and used to gauge ease
of extudability. For samples requiring characterization of tensile
properties, the materials are extruded through a 19 mm.times.3 mm
rectangular die plate onto a moving belt to minimize extrudate
draw-down.
Tensile and Elongation:
[0119] ASTM Type IV dogbones were die cut from the extruded strips.
The dog-bones were then tensile tested using a Lloyd Instruments
universal testing machine produced by Ametek, Inc. A one-inch gauge
length was used in the strain calculations. The cross-head speed
was varied in an attempt to meet ASTM standards of tensile test
duration lasting between 30 seconds and 3 minutes. A stress/strain
curve was generated for the test samples.
Example 1
Silica Sand
[0120] Silica sand was obtained from Sterling Supply Inc.,
Minneapolis, Minn. (1-50 lb bag stock #5030). NZ12 coated and
uncoated silica sand possessing an average particle size of 180
microns) was compounded into THV 220A.
[0121] Before compounding or coating, the pycnometer and press
densities were measured to calculate the packing fraction of silica
sand. The helium pycnometer density was found to be 2.65 g/cc. The
silica sand was pressed to a load of 10000 lbf ram pressure (8200
psi) and pumped and released 30 times.
TABLE-US-00002 TABLE 2 Density of silica sand using various test
methods. Density Description [g/cc] Pycnometer 2.6503 8200 psi
2.004 (packing fraction = 2.00/2.65 = 75.5%)
[0122] Silica sand was coated with 2 pph Kenrich NZ12 and
compounded into Dyneon THV 220A to form the test composite. The
coated sand was analyzed with the lab pycnometer to determine the
coated density which was found to be 2.56 g/cc. The target packing
in the composite was set at 60 vol % silica sand. The 60 vol %
particle was maintained for the coated and uncoated materials with
the understanding that the NZ12 is a part of the continuous polymer
phase not the particle phase.
[0123] Both coated and uncoated materials were compounded using the
lab 19 mm twin screw extruder using a temperature profile of
185.degree. C. in all five zones and a 19 hole die; screw speed was
kept constant at 185 RPM. Both materials were fed into the
compounder with KTron gravimetric twin screw feeders. The total
material throughput rate was maintained at 60 cc/min. Torque was
lower for the interfacially modified material (40% vs 55-60% for
the unmodified). Both materials were cut into pellets at the die
face with the lab compounder four blade pellet cutter and air
cooled. For both materials the pellets stuck together some,
indicating that the 60 volume % particulate phase was not at the
maximum possible particle loading.
[0124] Both materials were then extruded using a flat temperature
profile of 150.degree. C. and a constant screw speed of 40 RPM. The
unmodified material extruded with a melt pressure of 1300-1700 psi
and a motor load of 4.5-5.4 amps. The modified material ran fine
with a melt pressure of 1350-1500 psi and a motor load of 5.8
amps.+-.0.2 amps.
[0125] Four ASTM 638 type four dog bones were cut from the extruded
strips of each material. Each sample was tested with a constant
extension rate of one inch per minute and the force required was
recorded. Table 3 and FIG. 2 summarizes the tensile properties and
composition of the materials created in this experiment and also
provides previous data on pure THV 220A as a comparison. The
unmodified samples underwent relative brittle fracture compared to
the modified which experienced significant elongation before
fracture. Tensile properties were drastically different with the
unmodified yield strength much higher (5.4 MPa vs 0.7 MPa) and the
elongation was much higher for the modified material (600% at break
vs 20% at break).
TABLE-US-00003 TABLE 3 Summary of Tensile Properties of Silica Sand
Materials Compared to Pure THV 220A Sample Composition Example- 1a
1b 1c wt % THV 220A [1.9 g/cc] 100.0% 31.8% 29.8% wt % Silica [2.65
g/cc] 0.0% 68.5% 68.7% wt % Coating 0.0% 0.0% 1.5% vol % THV 220A
[1.9 g/cc] 100.0% 39.1% 36.1% vol % Silica [2.65 g/cc] 0.0% 60.9%
60.5% vol % Coating 0.0% 0.0% 3.4% Puck Density [g/cc] 1.9 2.36
2.32 Calculated Target Density [g/cc] 1.9 2.35 2.32 Deviation from
Target 0.00% 0.29% 0.07% Physical properties of extruded 3 .times.
20 mm strip ASTM 638-4 dog bones Tensile Stress at Yield [Mpa] 3.0
5.4 0.6 % Elongation at Yield 55 9 12 Maximum Tensile Stress [Mpa]
10.2 5.4 1.8 % Elongation at Break (Max) 1005 21 595
Example 2
Zirconium Silicate
[0126] We obtained the zirconium silicate (ZS) spheres in the
70-125 micron size range (product name ZS B0.07) from Stanford
Materials (CA). The uncoated helium pycnometer density of the
zirconium silicate was determined to be 3.78 g/cc. Packing density
using the metallurgical press was determined to be 2.42 g/cc
yielding a packing fraction of 64.1% for the unmodified and 2.53
g/cc and 69.2% for partiulates modified with 2 phr NZ-12 (the
pycnometer result for the modified zirconium silicate was 3.657
g/cc). The results indicate that the interfacial modifier increases
the ability to increase packing of the zirconium silicate
spheres.
[0127] Unmodified ZS-B0.07 was compounded with THV 220A using the
19 mm B&P laboratory compounder at a target loading of 60
volume %. The compounder was equipped with a 3 hole die and was
using the 4 blade pellet cutter at 100 RPM. At a set compounder
screw speed of 185 RPM with a flat 185.degree. C. temperature
profile, the compounder exhibited torque of 30-35% of max, pressure
of 80-110 psi and a melt temperature of 200.degree. C. A puck of
the compounded pellets had a density of 3.03 g/cc which was within
2% of the target density.
[0128] Interfacially modified ZS was also compounded with THV 220A
also at a target loading of 60 volume % zirconium silicate. To
maintain a 60.1 vol % particles (treating the ZS as the particle
and the coating layer and the THV as the continuous matrix phase in
the composite) a mass ratio of 23.2 wt % THV and 76.8 wt % coated
ZS was used. A metallurgical press of the compounded pellets
produced a puck with a density of 2.965 g/cc which was within 2% of
the target density.
[0129] Both materials were extruded at temperature profile of 154,
150, 150, 140.degree. C. from throat to die but motor load was not
recorded for either run due to attention on feed and extrudate
using a 19 mm 3 mm rectangular shaped die plate. The finish was
good for both materials, no noticeable difference, but the
flexibility of the materials was obvious when a section was bent.
The modified material was flexible where as the unmodified material
was brittle.
[0130] Tensile samples were cut then pulled at one inch per minute
using the tensile tester. FIG. 3 shows the average tensile response
of the coated and uncoated materials compared to pure THV 220A.
Stress/strain curves were determined using type-IV dogbones with
brittle (uncoated) and elastic (when coated at 2 phr of NZ-12)
behavior observed.
[0131] Because the physical properties (tensile stress/stain
curves) and processing within compounding and extrusion were
favorable when loading THV220 to about 60 volume % zirconium
silicate, we proceeded with a process study to confirm the
metallurgical press results that reveal the ability to pack the
coated zirconium silicate to a higher level than the uncoated
material.
2.sup.nd Experiment: Determining Maximum Packing Level with the 19
mm Compounder:
[0132] Throughout the experiments, the volumetric output was kept
constant at 60 cc/min with a flat temperature profile of
185.degree. C. and a screw speed of 185 RPM and a three hole pellet
die plate. Tables 4 and 5 show data for composites with unmodified
and modified particle.
TABLE-US-00004 TABLE 4 Uncoated Vol. % Z. Silicate Torque (%)
Pressure (psi) Melt T (.degree. C.) 0 (all THV) 25 0 195 60 40-45
210 204 64 50 430 208 68 65 750-810 224 70 65 900 235 72 Overload
-- -- 70 (replicate)* 75-80 1070 242 71* 95 1270 250 *Note,
gathered strands and determined puck density of 3.05 g/cc vs a 3.26
composite density that would correlate to 70%. This value indicates
that the composite is starved of polymer resulting in voids within
the composite.
TABLE-US-00005 TABLE 5 Coated with 2% NZ-12 Vol. % Zr Silicate
Torque (%) Pressure (psi) Melt T (.degree. C.) 70 40 400 +- 50 211
72 60 400 +- 50 230 74 60 300 229 77 50 220 222
Note the reduced torque and pressures associated with the modified
material run at a given volumetric level (e.g. 70 volume %).
Processing at a higher packing indicated a lower particle: particle
friction level in the modified particles; a puck density of the
combined levels (70-77 volume %) was 2.96 g/cc. The results
indicate that the composite samples were polymer starved at
particulate levels beyond the packing fraction (a trend that
explains the lower torque and pressures as zirconium silicate
levels increased).
Example 3
Aluninosilicate
[0133] G200 aluminosilicate garnet spheres were obtained from 3M
Corporation (St. Paul, Minn.). The solid beads were interfacially
modified with NZ12.
Batches of 500 grams of beads were prepared in the stock pot with a
loading of 2 wt % NZ12. The 2 wt % refers to 2% of the weight of
the material to be modified so in this case 10 grams of NZ12 were
used resulting in a coated product that was 98.04 wt % beads and
1.96 wt % modifier. The NZ12 was first dissolved in excess
isopropanol (IPA). The IPA/NZ12 solution was added to the beads.
Additional IPA was used to rinse the IPA/NZ12 solution container to
ensure that all NZ12 was added to the beads. Further IPA was added
as needed to achieve a slurry in the stock pot. In total,
approximately 1000 ml of IPA was added to the 500 grams of G200
microspheres. The stock pot was heated until the IPA was
volatilized and the spheres returned to a dry flowable powder.
[0134] Next, the modified beads were compounded into THV 220A.
Samples of both the modified and unmodified beads were analyzed
with the Accupyc 1330 Pycnometer to determine their density. Using
the densities of NZ12 (1.06 g/cc), uncoated beads (2.66 g/cc), and
THV 220A (1.9 g/cc) weight based feed rates were calculated for
each loading level. Unmodified and interfacially modified beads
were compounded into THV 220A at 20 vol %, 40 vol %, 45 vo1% and
51.7 vol % of beads in the final composite. All samples were
compounded on 19 mm compounder with a 3 hole die and a rotating 4
blade pellet cutter onto a moving conveyer belt with ambient air
cooling. All samples were compounded with the same temperature
profile of 185.degree. C. in every zone. Pellets needed were shaken
in the collection bucket as they cooled so they would not stick
together. All samples compounded fine, never torqued out the
compounder (torque values ranged from 20% at low loading to 40% at
high loading) but the pressure was getting higher with the 51.7 vol
% samples. Holes in the 3 hole die would periodically plug and then
clear on their own resulting in back pressures ranging from 180-230
psi for the NZ12 modified sample and 160-240 psi for the unmodified
sample. Higher loading samples were rougher and the ceramic powder
was visible where as at the lower loading, samples were smoother
and evenly colored. The 19 hole die was used initially for the 20
vol % sample but the pellets stuck together as they were cut so the
3 hole die was used instead.
[0135] The 20%, 45%, and 51.7 volume % samples were extruded on the
1 inch single screw extruder equipped with a pressure gauge using a
19 mm.times.3 mm die plate assembly. The same temperature profile
of (154, 150, 150, 140.degree. C. from throat to die) was used for
all samples except the 20 vol % loading which used (180, 150, 150,
140.degree. C. from throat to die). The 40 volume % samples were
extruded on the extruder with no pressure gage. All samples
extruded fine, low loading had slight die swell. Samples extruded
on the non-pressure gage extruder had slightly rough finish which
looked to be from bubbling in the material.
[0136] ASTM 638 type 4 dog bones were cut from extruded strips of
each sample. Tension testing was performed on the tensile tester. A
1 inch gage length was used per the ASTM standard and a rate of 1
inch/min was used for each sample group. Two to four samples were
tested for each sample group. Samples of extruded THV 220A were
also tested. FIG. 4 and the table below summarize the results of
the tensile testing. Yield stresses were taken to be the first peak
in the plot or, when none was present, the point where the curve
started to "bend over" as determined approximately by observation
of plotted data. For the high loading composite samples containing
modified particles, ductile failure was observed where the material
tore slowly (over a few seconds) and failed. Composite samples
containing unmodified particles failed in a more brittle fashion
(no tearing). The samples of pure THV 220A and the 20 vol % loading
samples did not fail and extended to the maximum of the
machine.
[0137] FIG. 5 below shows the average tension and elongation curves
for each composite sample made. Since the tension testing was
performed with constant rate of extension, the average curves were
generated by averaging the stress for each sample at a given
extension. FIG. 5 shows just the lower extension of the two inch
extension region of FIG. 4.
Table 7 below outlines the relevant parameters and properties of
each sample in this experiment.
TABLE-US-00006 TABLE 6 Sample Composition Example 3a 3b 3c 3d 3e 3f
3g 3h 3i wt % THV 220A 100 74.0 73.5 51.7 50.3 47.0 45.0 40.0 38.0
wt % G-200 0 26.0 26.0 48.3 48.8 53.0 53.9 60.0 60.8 wt % NZ12 0
0.0 0.5 0.0 0.9 0.0 1.1 0.0 1.2 vol % THV 220A 100 80 79 60 58.0
55.4 52.5 48.3 45.3 vol % G-200 0 20 20 40 40.2 44.6 44.9 51.7 51.7
vol % NZ12 0 0 1.0 0 1.8 0 2.6 0 3.0 Density THV 220A [1.9 g/cc]
1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 Density G-200 [2.66 g/ce] 2.66
2.66 2.66 2.66 2.66 2.66 2.66 2.66 2.66 Puck Density [g/cc] 1.9
2.04 2.01 2.19 2.17 2.22 2.19 2.23 2.25 Calculated Target Density
1.9 2.05 2.04 2.21 2.19 2.24 2.24 2.29 2.26 Deviation from Target
0.00% 0.61% 1.43% 0.68% 0.64% 0.89% 2.23% 2.79% 0.44% Physical
properties of extruded 3 .times. 20 mm strip ASTM 638-4 dogbones
Tensile Stress at Yield [Mpa] 3.0 5.2 4.5 4.0 4.5 3.6 3.9 3.0 4.9
Elongation at Yield [%] 55 68 57 25 13 2 9 4 8 Tensile Stress at
Break [Mpa] 10.2 12.6 11.6 7.8 2.7 7.8 0.3 7.7 0.2 Elongation at
Break [%] 1000 980 1040 60 320 30 50 20 30
Example 4
Garnet
[0138] Garnet was obtained from Barton Garnet (Lake George, N.Y.);
60 mesh and 350 mesh. The Garnet was fully evaluated starting with
fundamental powder properties through interfacial modification,
compounding, and two end processes (extrusion and melt
molding).
Unmodified Powder
[0139] The particle size distribution of each sample product was
determined using ASTM stacked sieves and a roto-tap sifter. The
garnet packing fractions were characterized using a ratio of press
density (via metallurgical press) to that of true density (via the
helium pycnometer). Each of the two sizes were evaluated along with
a blend of 3:1 by weight of the 60 mesh to the 350 mesh. The tap
density was also determined using a Quanta-Chrome Dual Autotap
instrument set to 1000 tap cycles.
Interfacially Modified Powder
[0140] The packing fraction of the 3:1 ratio of large (60 mesh) to
fine (350 mesh) garnet blend was determined after modifying the
particles with 1.5 parts of NZ-12 per 100 parts of garnet using the
ratio of packing density (via metallurgical press) to that of true
density (via pyncometer).
Compounding with Fluorocarbon Polymer and Ethylene Vinyl
Acetate
[0141] The garnet (both modified and unmodified) was compounded
with THV 220A at volumetric loadings starting at 60 volume % and
increasing in increments of 4 volume % until over-torque occurred.
A constant volumetric output of 100 cm.sup.3-min.sup.-1 was
maintained throughout. The following compounder settings were used:
[0142] Flat temperature profile for all 5 zones at 185.degree. C.
[0143] Screw speed=250 rpm [0144] 19 hole die plate with rotating
cutter and conveyor belt
[0145] The blended garnet was also compounded/extruded into 1 inch
diameter glue sticks using the 19 mm twin screw compounder and HB
Fuller's (St. Paul, Minn.) HL7268 EVA based product. A volume
fraction of 70% was targeted with a desired volumetric output of
100 cc/min. The following compounder settings were used: Zone 1 to
5: 80.degree. C.: 80.degree. C.; 80.degree. C.; 80.degree. C.:
75.degree. C.: no additional heat from heater band Screw speed=120
rpm (we decreased RPM until an increase in torque occurred) with 1
inch pipe die.
[0146] The material had excessive droop as it was conveyed onto a
belt. As a result, the rough sticks were fed into a Wiley Mill and
ground. The ground material was pressed (at room temperature) into
a 1 inch diameter rod using the metallurgical press. A sole melt
molding stick was made and used for the melt molding work described
below.
Extrusion
[0147] Extrusion: The garnet/THV pellets were fed into a single
screw extruder with barrel temperatures maintained at 160.degree.
C.: 160.degree. C.: 150.degree. C.: 140.degree. C. (zone-1, zone-2,
zone-3, Die). Strips were extruded using a 3.times.19 mm die. Screw
speed was maintained between 20 and 27 rpm.
Tensile and Elongation
[0148] ASTM type-IV dog bones were cut from the THV based extruded
strips. An attempt was made to maintain reasonable tensile test
duration by varying the cross-head speed (i.e. a faster cross head
speed was used for the relatively elastic samples while a slower
rate was used for the non-elastic samples).
RESULTS
[0149] The garnet packing fractions of the 60 and 350 mesh sizes
were evaluated along with a blend of 3: 1 by weight of the 60 mesh
to the 350 mesh.
TABLE-US-00007 TABLE 7 packing fraction press density (g/cc) true
density (g/cc) (vol %) 60HPA 3.054 4.084 74.8% 350W 2.391 3.916
61.1% 3:1 Blend 3.115 4.050 76.9%
The tap density of the blended mix was 2.906 g/cc (71.8%). The tap
density may more accurately reflect attainable packing levels in
low pressure application processes like melt molding.
[0150] The packing fraction of the 3:1 ratio of large (60 mesh) to
fine (350 mesh) garnet blend modified with 1.5 wt % NZ12 possessed
a packing fraction of 82.2% (press density of 3.191 g-cm.sup.-3 and
a corresponding pycnometer density of 3.884 g-cm.sup.-3). The
increased packing behavior is similar to trends observed after
modifying other particles.
[0151] The garnet (both modified and unmodified) was compounded
into THV 220A. Puck densities were obtained and near the intended
target values:
TABLE-US-00008 TABLE 8 Unmodified garnet Modified garnet 3:1 60:350
calculated calculated actual puck mesh puck density actual puck
puck density density Volume % (g/cc) density (g/cc) (g/cc) (g/cc)
60% 3.19 3.17 3.16 3.12 64% Not determined Not determined 3.24 3.22
68% Not determined Not determined 3.33 3.32 72% Could not Could not
3.41 3.39 compound compound
In calculating the volumetric percentages, the interfacial modifier
is considered part of the continuous/polymer phase and only the
volume of the garnet considered the particulate phase. The reduced
and improved torque of the compounder and the associated reduced
and improved compounder pressures are shown in FIGS. 6 and 7. The
unmodified garnet had increased torque and pressure compared to the
more easily compounded interfacially modified garnet. Garnet, when
modified with 1.5 parts of NZ-12 per 100 parts of particle
exhibited vastly different rheological and viscoelastic properties
when compared to an untreated control:
[0152] Higher packing fraction was attained and lower compounder
torques and pressures occurred.
[0153] The blended garnet was also compounded/extruded into 1 inch
diameter glue sticks using the 19 mm twin screw compounder and HB
Fuller's HL7268 EVA based product. [0154] Torque=50% [0155] Melt
temperature=84.degree. C. [0156] Pressure=120 psig
[0157] Note that pellets of the EVA composite product could be
pressed into a solid stick at room temperature under significant
pressures (e.g. a few thousand psi exerted within a metallurgical
press). The ground material can be forced into a loose ball using
hand pressure, much like wet snow.
[0158] Tensile and Elongation data was collected. In short, the
modifier effectively increases composite elasticity and elongation
at a given garnet particulate loading. The elongation to break
decreases as the loading increases whether or not the particles
were interfacially modified. FIG. 1 shows the relationship of the
use of an interfacial modifier on various levels of loading of
garnet particles in a fluorocarbon polymer. Without interfacial
modifier the material is brittle and fails at minimum elongation.
With interfacial modifier the composite has substantial
elongation.
[0159] The stress strain curves for all populations are shown in
FIGS. 8 through 14. In FIGS. 8-10 at 60 to 68% garnet at 1.5%
interfacially modified material, the composite has excellent
elongation or extension. The very high packing amounts (FIG. 11) or
the absence of an interfacially modified particulate (FIGS. 10-14)
obtained poor extension.
[0160] The composites of the invention can be used in a number of
applications that use either the properties of the particulate in
the composite or the overall viscoelastic properties of the
composite. The viscoelastic materials can be formed into objects
using conventional thermoplastic polymer forming techniques
including extrusion, injection molding, compression molding, and
others. The composites of the invention can be used in many
specific applications such as in transportation (including
automotive and aerospace applications), abrasive applications used
to either remove materials such as paint or corrosion or dirt or
stains, uses where high density (6 to 17 g-cm.sup.-3) or low
density (0.2 to 2 g-cm.sup.-3) is useful, hunting and fishing
applications or in mounting applications where a base or mounting
weight is needed. Specific applications include fishing lure and
jig, abrasive pads with aluminum oxide, silica or garnet used like
sand paper or sanding blocks, abrasive pads with cleaning materials
used like Scothbright.RTM. pads for cleaning surfaces, brake pads
(aluminum oxide or garnet), apex seals for Wankel or rotary
engines, fuel applications (line, tank or seal), engine or drive
train counterweight, automotive or truck wheel weight. The
composites of the invention include a particulate and a polymer
phase that combine to obtain in the composite valuable properties.
These properties include improved thermal properties (both heat
sink and insulation character), improved impact resistance,
improved hardness, improved frictional or abrasive character,
improved barrier properties to the mass transfer of vapor or liquid
materials through the composite, improved acoustic insulation
properties. The composites obtain these properties form a selection
of the particulate and polymer and a selection of particulate
loading.
[0161] An inorganic composite and polymer composite can be made
comprising about 30 to 87 vol.-% of an inorganic mineral particle
having a particle size P.sub.S greater than about 5 microns having
a coating of about 1 to about 0.005 to 5 wt-% of an interfacial
modifier, the percentage based on the composite; and a polymer
phase. The particle of the composite comprises a mineral having a
particle size P.sub.S of about 10 to 400 microns, about 15 to 350
microns or greater than about 10 microns with a circularity of the
mineral about 12.5 to 50. In one embodiment particle comprises a
silicate mineral having a particle size P.sub.S of about 5 to 150
microns.
[0162] The composite has a tensile strength of about 0.1 to 15
times or about 5 to 25 times that of the base polymer. The
composite of claim 1 wherein the composite has a tensile strength
of 5 and 100 times that of the base polymer, a tensile elongation
of about 5% and 100% or a tensile elongation of about 10% and 100%
of the base polymer. In one embodiment, the composite has a tensile
strength of about 10 to 20 times that of the base polymer and a
tensile elongation of about 15% and 100% of base polymer and the
composite has a thermoplastic shear of at least 5 sec.sup.-1. In
another embodiment, the composite has a tensile strength of at
least 0.2 MPa and a thermoplastic shear of at least 5 sec.sup.-1.
The composite comprises greater than 30 vol.-% or 50 vol.-% of the
inorganic mineral. In the composite, the composite comprises a
particulate wherein the majority of the particulates having a
particulate size P.sub.S of about 10 to 1000 microns; and a
fluoropolymer phase. The inorganic mineral has a particle size
P.sub.S of about 10 to 200 microns and the composite additionally
comprises a second particulate with a particle size P.sub.S.sup.1
that differs from the inorganic composite by at least 5 microns,
alternatively, the inorganic mineral has a particle size P.sub.S
according to the formula P.sub.S<2 P.sub.S.sup.1 or
P.sub.S>0.5 P.sub.S.sup.1; wherein P.sub.S is the particle size
of the inorganic mineral and P.sub.S.sup.1 is the particle size of
the second particulate. The second particulate comprises a ceramic
particulate, a glass microsphere, a solid glass sphere, or a second
inorganic composite, a hollow glass sphere having a particle size
P.sub.S of about 10 to 300 microns, a solid glass sphere having a
particle size P.sub.S of about 5 to 300 microns, a silica having a
particle size P.sub.S of about 5 to 300 microns, a silica or silica
sand having a particle size P.sub.S of about 75 to 300 microns. The
silica particle can comprise a zirconium silicate. The polymer can
comprise a fluoropolymer, a fluoro-elastomer, a polyamide, a nylon,
a poly (ethylene-co-vinyl acetate), a synthetic rubber, a polyvinyl
chloride or other such polymers or mixtures. The particles can have
a coating of about 0.01 to 3 wt % of an interfacial modifier based
on the composite. The particles have an excluded vol. of about 13
vol.-% to about 70 vol.-%, or about 13 vol.-% to about 60
vol.-%.
[0163] A preferred particulate polymer composite comprises a
inorganic mineral particle in a polymer phase, the composite
comprising about 90 to 40 vol.-% of an inorganic mineral particle,
having a density greater than 0.10 gm-cm.sup.-3 and less than 5
gm-cm.sup.-3, a particle size P.sub.S greater than 10 microns, a
circularity greater than 14 and an aspect ratio less than 3; and
about 10 to 70 vol.-% of a polymer phase. The particulate comprises
a layer comprising about 0.005 to 3 wt.-% of an interfacial
modifier. The composite density is about 0.9 to 15 gm-cm.sup.-3,
about 1 to 5 gm-cm.sup.-3 or about 1 to 2 gm-cm.sup.-3. A shaped
article can be made comprising the composite with about 87 to 48
vol.-% of a particulate having a particle size P.sub.S greater than
10 microns, and having a particle size P.sub.S distribution having
at least 10 wt.-% of a particulate within about 10 to 100 microns,
at least 10 wt.-% of the polymer particulate within about 100 to
500 microns, a circularity greater than 13 and an aspect ratio less
than 1:3; about 13 to 51 vol.-% of a polymer phase.
[0164] A method of forming an inorganic and polymer composite
material can be used wherein the extrudible mass comprises a
polymer phase and a particle phase, the particle phase comprising a
coating of an interfacial modifier in an amount of about 0.005 to 5
wt-% of an interfacial modifier or of about 0.01 to 3 wt % of an
interfacial modifier based on the composite, the particles
comprising a first particle particulate having a circularity of
greater than about 15 or 10 and a second substantially round
particulate having a circularity of about 12.5 to 15; the second
particulate comprising greater than 5 vol.-% of the composite
wherein upon extrusion, the shear on the extrudible mass, the wear
of an extruder and the extrusion pressure is reduced. In the
method, the second substantially round particle is used at a about
13 to 75 vol.-% of a particulate phase comprising 13 to 87 vol.-%
of the composite. Lastly, the particle size P.sub.S of the first
particle differs form the second round particle size P.sub.S of the
second particle by about 5 microns or the particle sizes differ
such that the first particle size is greater than twice the size or
half the size of the second round particle. The presence of the
second round particle reduces wear, reduces pressure and reduces
shear imposed on the extrudible mass comprising the polymer and
particulate. The composite with a substantial loading of
particulate, can pose a challenge to the extruder. Any improvement
in the processability improves extruder lifetime and product
quality.
[0165] While the above specification shows an enabling disclosure
of the composite technology of the invention, other embodiments of
the invention may be made without departing from the spirit and
scope of the invention. Accordingly, the invention is embodied in
the claims hereinafter appended.
* * * * *