U.S. patent application number 16/546831 was filed with the patent office on 2019-12-19 for reduced density hollow glass microsphere polymer composite.
This patent application is currently assigned to Tundra Composites, LLC. The applicant listed for this patent is Tundra Composites, LLC. Invention is credited to Kurt Heikkila, John Kroll, Rodney Williams.
Application Number | 20190382553 16/546831 |
Document ID | / |
Family ID | 43030593 |
Filed Date | 2019-12-19 |
United States Patent
Application |
20190382553 |
Kind Code |
A1 |
Heikkila; Kurt ; et
al. |
December 19, 2019 |
REDUCED DENSITY HOLLOW GLASS MICROSPHERE POLYMER COMPOSITE
Abstract
The invention relates to a hollow glass microsphere and polymer
composite having enhanced viscoelastic and rheological
properties.
Inventors: |
Heikkila; Kurt; (Marine on
the St. Croix, MN) ; Williams; Rodney; (Stacy,
MN) ; Kroll; John; (Blaine, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tundra Composites, LLC |
White Bear Lake |
MN |
US |
|
|
Assignee: |
Tundra Composites, LLC
White Bear Lake
MN
|
Family ID: |
43030593 |
Appl. No.: |
16/546831 |
Filed: |
August 21, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15680835 |
Aug 18, 2017 |
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16546831 |
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14965997 |
Dec 11, 2015 |
9771463 |
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15680835 |
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12769553 |
Apr 28, 2010 |
9249283 |
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14965997 |
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61173791 |
Apr 29, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08K 3/22 20130101; C08K
2201/005 20130101; C08J 2327/18 20130101; C08K 7/28 20130101; C08K
9/04 20130101; C08J 2327/20 20130101; C08K 2003/2227 20130101; C08J
2327/16 20130101; C08L 21/00 20130101; C08J 5/04 20130101; B60C
1/00 20130101; C08K 7/28 20130101; C08L 21/00 20130101; Y10T
428/249974 20150401; C08K 9/00 20130101 |
International
Class: |
C08K 3/22 20060101
C08K003/22; C08J 5/04 20060101 C08J005/04; C08K 9/00 20060101
C08K009/00; C08L 21/00 20060101 C08L021/00; C08K 9/04 20060101
C08K009/04; C08K 7/28 20060101 C08K007/28; B60C 1/00 20060101
B60C001/00 |
Claims
1-95. (canceled)
96. A melt processing method of manufacturing a hollow glass
microsphere and polymer composite from a mixture, said method
comprising: (a) pre-treating a hollow glass microsphere with an
effective composite forming amount of an interfacial modifier
coating wherein the hollow glass microsphere has a particle size of
at least about 5 microns; (b) combining a thermoplastic polymer
phase with about 30 to 95 volume % of a pre-treated interfacial
modifier coated hollow glass microsphere, in an amount that can
substantially occupy excluded volume of a hollow glass microsphere
particle distribution in the composite; and (c) melt process
compounding the mixture to form the composite comprising the
pre-treated hollow glass microspheres within the polymer phase;
wherein the hollow glass microsphere exhibits a circularity greater
than 13 and an aspect ratio less than 1:3; and wherein the
interfacial modifier coating allows for greater freedom of movement
between the pre-treated hollow glass microsphere within the polymer
phase compared to the same composite without the exterior coating
on the hollow glass microsphere, when measured under the same
conditions.
97. The method according to claim 96, wherein about 40 to 70 volume
% of the hollow glass microsphere composite comprises the polymer
phase.
98. The method according to claim 96, wherein the composite
comprises about 0.02 to 3 wt.-% of the interfacial modifier.
99. The method of claim 96 wherein the polymer phase has a density
of about 0.86 gm-cm.sup.-3.
100. The method of claim 96, wherein the composite has a density of
about 0.4 to 5 gm-cm.sup.-3.
101. The method of claim 96 wherein the composite additionally
comprises a solid particulate or a fiber, the particulate having a
particle size (P.sub.s) of about 5 to 1000 microns and the fiber
having an aspect ratio of greater than 10.
102. The method of claim 96 wherein after compounding, the method
includes extruding the composite.
103. The method of claim 97 wherein the polymer phase comprises a
polyamide, poly (ethylene-co-vinyl acetate), a synthetic rubber, a
polyvinyl chloride, a fluoropolymer, a polyolefin, a thermoset
polymer.
104. The method according to claim 96, wherein said melt processing
comprises injection molding the composite.
105. The method according to claim 96, wherein said melt processing
comprises compression molding the composite.
106. The composite formulation of claim 96 wherein the microsphere
is a hollow glass microsphere.
107. The composite formulation of claim 96 wherein the composite
formulation has a tensile strength of about 0.1 to 10 times that of
the polymer phase.
108. The composite of claim 96 wherein the composite formulation
has a tensile elongation of about 15% to 90% of the polymer
phase.
109. The composite of claim 96 wherein the composite formulation
has a thermoplastic shear at least about 5 sec.sup.-1.
110. The composite formulation of claim 96 wherein the composite
formulation has a tensile strength of at least 0.2 MPa and a
thermoplastic shear of at least 5 sec.sup.-1
111. The composite formulation of claim 96 wherein the hollow glass
microsphere has a particle size P.sub.S of about 5 to 300 microns.
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 hollow glass
microsphere and a polymer with modifiable properties to produce
enhanced products. The novel properties are produced in the
composite by novel interactions of the components. The hollow glass
microsphere and polymer composite materials are a unique
combination of a hollow glass microsphere typically particulate
components and a polymer material that optimizes the composite
structure and characteristics through blending the combined polymer
and hollow glass micros to 90% of the base polymer 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.
[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 hollow glass
microsphere and a polymer having improved and novel properties
methods of making and applications of the materials. The material
of the invention is provided through a selection of non metallic,
hollow glass microsphere particle specie, particle size (P.sub.s)
distribution, molecular weight, and viscoelastic character 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
hollow glass microsphere 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 and the selection of the
particulate or mixed non-metal, inorganic, ceramic or mineral
particulate, will obtain the enhanced properties.
BRIEF DISCUSSION OF THE DRAWINGS
[0009] FIGS. 1 to 5 shows enhanced rheological properties in a
sealant.
DETAILED DISCUSSION OF THE INVENTION
[0010] The invention relates to novel composites made by combining
a hollow glass microsphere particulate with a polymer to achieve
novel physical electrical surface and viscoelastic properties. A
hollow glass microsphere 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 hollow and spherical.
[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 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 Type of Interaction Strength Bond Nature Proportional 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 Short
range r.sup.-3 strong VDW Ion-induced Weak Very short range
r.sup.-4 dipole VDW Dipole- Very weak Extremely short r.sup.-6
induced dipole range VDW London Very weak.sup.a Extremely short
r.sup.-6 dispersion forces range .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 that are 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 particle
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. In 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 A. 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. We believe an
interfacial modifier is an organic material that provides an
exterior coating on the particulate promoting the close association
but no reactive bonding 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. %. For the purpose of this disclosure, the term
"particulate" typically refers to a material made into a product
having a distribution or range of particle size. The size can be
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.
The glass can be combined with a second particulate such that the
second particle differs from the glass by at least .+-.5 microns,
or has a particle size such that according to the formula
P.sub.S.gtoreq.2 P.sub.S.sup.1 or P.sub.S.ltoreq.0.5 P.sub.S.sup.1
wherein P.sub.S is the particle size of the hollow glass
microsphere and P.sub.S.sup.1 is the particle size of the
particulate.
[0021] 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.
[0022] 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.
[0023] 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 "non-metal, inorganic or
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.
Particle Morphology Index
[0024] 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.
[0025] 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 .rho.m and 2) Particle surface
characteristics that are on the order of the size of the
interfacial modifier being applied.
[0026] 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)
[0027] 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 -40US 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.
[0028] 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
diameter within a given mass of material. There is 100 times the
surface area for particles of 1,500 .mu.m diameter compared to 15
.mu.m.
[0029] 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)
[0030] The benefits of interfacial modification is independent of
overall particle shape. Particles with an aspect ratio of 1 (hollow
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.
[0031] 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 particle size (P.sub.s) or diameter, r.sub.a is aspect
ratio.
[0032] 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)
[0033] 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.
[0034] Such materials such as 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.
[0035] 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)
[0036] 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.
[0037] 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.
[0038] 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 particle size (P.sub.s) or diameters and aspect ratios,
some roughness and porosity can range from 200 to 10.sup.4. Other
particles with a broadened range of sizes or diameters 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.
[0039] 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 %.
[0040] 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.
[0041] 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.
[0042] 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 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 secularity 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.
[0043] In the composites of the invention, the van der Waals'
forces occur between collections of hollow glass microspheres 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
glass microsphere, non-metal, inorganic or mineral particulates
that are in the range of van der Waals' strength, i.e., ranges and
definitions if appropriate.
[0044] In a composite, the hollow glass microsphere is usually much
stronger and stiffer than the matrix, and gives the composite its
designed properties. The matrix holds the hollow glass microspheres
in an orderly high-density pattern. Because the hollow glass
microspheres are usually discontinuous, the matrix also helps to
transfer load among the hollow glass microspheres. Processing can
aid in the mixing and filling of the hollow glass microsphere in
the composite. To aid in the mixture, a surface chemical reagent
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.
[0045] Hollow glass spheres (including both hollow and solid) are a
useful non-metal or inorganic particulate. These spheres are strong
enough to avoid being crushed or broken during further processing
of the polymeric compound, such as by high pressure spraying,
kneading, extrusion or injection molding. In many cases these
spheres have densities close to, but more or less, than that of the
polymeric compound into which they are introduced in order that
they distribute evenly within the compound upon introduction and
mixing. Furthermore, it is desirable that these spheres be
resistant to leaching or other chemical interaction with their
associated polymeric compound. The method of expanding solid glass
particles into hollow glass spheres by heating is well known. See,
e.g., U.S. Pat. No. 3,365,315. Glass is ground to particulate form
and then heated to cause the particles to become plastic and for
gaseous material within the glass to act as a blowing agent to
cause the particles to expand. During heating and expansion, the
particles are maintained in a suspended state either by directing
gas currents under them or allowing them to fall freely through a
heating zone. Sulfur, or compounds of oxygen and sulfur, serves as
the principal blowing agent.
[0046] A number of factors affect the density, size, strength,
chemical durability and yield (the percentage by weight or volume
of heated particles that become hollow) of hollow glass spheres.
These factors include the chemical composition of the glass; the
sizes of the particles fed into the furnace; the temperature and
duration of heating the particles; and the chemical atmosphere
(e.g., oxidizing or reducing) to which the particles are exposed
during heating. The percentage of silica (SiO.sub.2) in glass used
to form hollow glass spheres should be between 65 and 85 percent by
weight and that a weight percentage of SiO.sub.2 below 60 to 65
percent would drastically reduce the yield of the hollow
spheres.
[0047] Useful hollow glass spheres having average densities of
about 0.1 grams-cm.sup.-3 to approximately 0.7 grams-cm.sup.-3 or
about 0.125 grams-cm.sup.-3 to approximately 0.6 grams-cm.sup.-3
are prepared by heating solid glass particles.
[0048] For a product of hollow glass spheres having a particular
desired average density, there is an optimum sphere range of sizes
of particles making up that product which produces the maximum
average strength. A combination of a larger and a smaller hollow
glass sphere wherein there is about 0.1 to 25 wt. % of the smaller
sphere and about 99.9 to about 75 wt. % of larger particles can be
used were the ratio of the particle size (P.sub.s) of the larger
particles to the ratio of the smaller is about 2-7:1.
[0049] Hollow glass spheres used commercially can include both
solid and hollow glass spheres. All the particles heated in the
furnace do not expand, and most hollow glass-sphere products are
sold without separating the hollow from the solid spheres.
[0050] Preferred hollow glass spheres are hollow spheres with
relatively thin walls. Such spheres typically comprise a
silica-line-oral silicate hollow glass and in bulk form appear to
be a white powdery particulate. The density of the hollow spherical
materials tends to range from about 0.1 to 0.8 g/cc this
substantially water insoluble and has an average particle size
(P.sub.s) that ranges from about 10 to 250 microns.
[0051] In the past, an inorganic hollow glass sphere has been used
in polymers such as nylon, ABS, or polycarbonate compositions or
alloys thereof. In nylons, at a particulate loading ranges from a
few percent to as much as 20 vol. %, however, in our view, the
prior art inorganic materials become brittle and lose their
viscoelastic character as the volume percentage of particulate
exceeds 20 or 25 vol. %. In Applicants compositions, the materials
maintain both an effective composite formation of loadings of
greater than 20% but also maintain substantial viscoelasticity and
polymer characteristics at polymer loadings that range greater than
25 vol. %, greater than 35 vol. %, greater than 40 vol. % and
typically range from about 40 vol. % to as much as 95 vol. %. In
these ranges of particulate loading, the composites in the
application maintain the viscoelastic properties of the polymer in
the polymer phase. As such within these polymer loadings,
Applicants have obtained useful elongation at break wherein the
elongations can be inaccessive 5%, inaccessive 10%, inaccessive
20%, and can range from about 20 to 500% elongation at break.
Further, the tensile yield point can substantially exceed the prior
art materials and can range from about 5 to 10% elongation.
[0052] 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 non-metal, inorganic or 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.
[0053] 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 non-toxic, is a
bright white particulate that can be easily combined with either
non-metal, inorganic or mineral particulates and/or polymer
composites to enhance the novel characteristics of the composite
material and to provide a white hue to the ultimate composite
material.
[0054] We have further found that a blend of two, three or more
non-metal, inorganic or minerals in particulate form can, obtain
important composite properties from all of non-metal, inorganic or
minerals 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 blended composite of two or three different non-metal,
inorganic or minerals that could not, due to melting point and
other processing difficulties, be made into a blend without the
methods of the invention.
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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 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 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
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".
[0071] 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.
[0072] 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.
[0073] 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' copending patent
application Ser. No. 01/03,195, filed Jan. 31, 2001.
[0074] 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.
[0075] 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.
[0076] The choice of interfacial modifiers is dictated by
particulate, polymer, and application. The particle is coated even
if having substantial morphology. 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 materials are almost exclusively refractory metals
such as tungsten or osmium. These 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 of 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.
[0077] Preferred titanates and zirconates include isopropyl
tri(dioctyl)pyrophosphato titanate (available from Kenrich
Chemicals under the designation KR38S), 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
close association between the particulate surface and polymer is
maximized.
[0078] 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.
[0079] 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.
[0080] 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 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 reacted with the particulate in
aprotic solvent such as toluene, tetrahydrofuran, mineral spirits
or other such known solvents.
[0081] 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 independently a hydrocarbyl, C1-C12 alkyl
group or a C7-20 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.
[0082] The composite materials having the desired physical
properties can be manufactured as follows. In a preferred mode, the
surface of the particulate is initially prepared, the interfacial
modifier is coated on 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. 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.
[0083] 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.
[0084] 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: [0085] 1) Solvating the
interfacial modifier or polymer or both; [0086] 2) Mixing the
particulate into a bulk phase or polymer master batch: and [0087]
3) Devolatilizing the composition in the presence of heat &
vacuum above the Tg of the polymer.
[0088] When compounding with twin screw compounders or extruders, a
preferred process can be used involving twin screw compounding as
follows. [0089] 1. Add particulate and raise temperature to remove
surface water (barrel 1). [0090] 2. Add interfacial modifier to
twin screw when filler is at temperature (barrel 3). [0091] 3.
Disperse/distribute surface chemical treatment on particulate.
[0092] 4. Maintain temperature to completion. [0093] 5. Vent
by-products (barrel 6). [0094] 6. Add polymer binder (barrel 7).
[0095] 7. Compress/melt polymer binder. [0096] 8.
Disperse/distribute polymer binder in particulate. [0097] 9.
Combine modified particulate with polymer binder. [0098] 10. Vacuum
degas remaining products (barrel 9). [0099] 11. Compress resulting
composite. [0100] 12. Form desired shape, pellet, lineal, tube,
injection mold article, etc. through a die or post-manufacturing
step.
[0101] Alternatively in formulations containing small volumes of
continuous phase: [0102] 1. Add polymer binder. [0103] 2. Add
interfacial modifier to twin screw when polymer binder is at
temperature. [0104] 3. Disperse/distribute interfacial modifier in
polymer binder. [0105] 4. Add filler and disperse/distribute
particulate. [0106] 5 Raise temperature [0107] 6. Maintain
temperature to completion. [0108] 7. Compress resulting composite.
[0109] 8. Form desired shape, pellet, lineal, tube, injection mold
article, etc. through a die or post-manufacturing step.
[0110] Certain selections of polymers and particulates may permit
the omission of the interfacial modifier and their related
processing steps.
Experimental Section
[0111] 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.
[0112] 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:
[0113] 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.
[0114] 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:
[0115] To interfacially modify particles at a lab scale, the
interfacial modifier is first solubilized with isopropyl alcohol
(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:
[0116] 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:
[0117] 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:
[0118] 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
Hollow Glass Spheres
[0119] A supply of iM30k hollow glass bubbles were obtained from 3M
Corporation (St. Paul, Minn.). The bubbles possess a density of
approximately 0.6 g/cc. The bubbles were interfacailly modified
with KR238S (KenRich Chemicals) with 4.8 parts of interfacial
modifier to 100 parts particulate. The polymer phase was THV220
from Dyneon (St. Paul, Minn.). The bubbles were compounded into the
polymer phase to a loading of 60 volume % hollow glass bubbles in
the polymer phase. Samples were then extruded and ASTM tensile
dogbones specimens made and tensile tested. Additionally, puck
samples were made via the metallurgical press to confirm the
formulations were near the targeted values.
[0120] Obvious differences were apparent during compounding. The
product without modifier was brown/tan in color exiting the die
plate, indicating degradation of the material. Additionally, the
bubbles did not feed well and bridged at the infeed throat of the
machine. As a result, the volumetric throughput had to be reduced
from 60 to 40 ml per minute. The puck density of the compounded
product was 1.23 g/cc, indicating that many glass bubbles broke
during compounding (a value of 1.10 g/cc would be obtained at the
target loading without any glass bubble breakage). The composite
products were brittle; failing at an elongation of about 0.3 inches
(FIG. 2).
[0121] The composite containing the interfacially modified glass
bubbles possessed lower density (1.15 g/cc vs 1.23 g/cc) indicating
less bubbles broke during processing and that the final composite
contained more intact glass bubbles than the composite with the
unmodified bubbles. Additionally, the particles fed well into the
throat of the compounder thereby allowing a volumetric throughput
of 60 ml per minute to be maintained. The composite exiting the
compounder die plate was white. The extruded composite was very
flexible, elongating to about 5 to 8 inches at break (FIG. 4).
[0122] iM30k hollow glass bubbles were obtained from 3M Corporation
(St. Paul, Minn.). The bubbles possessed a density of approximately
0.62 g/cc. The concept that successful loading of the hollow glass
spheres at high volumetric loading within a composite would have
exceptionally low density and possibly other benefits as well
(namely low thermal and acoustical conduction etc.) was conceived.
Varying levels of NZ-12 were applied to the glass beads at a range
of 0 to 3 weight percent. Pellet compounding was completed on a 19
mm co-rotating twin screw extruder using our 3 hole die plate. Our
feed rates were controlled sufficiently to get close to our
targeted volumetric levels. Puck density calculations were used to
confirm the ratio of the 0.6.times. specific gravity glass beads to
the 1.9 specific gravity THV polymer and to back calculate the
ratio of glass bead to polymer in the generated samples.
Furthermore, we added the glass beads to the throat of the machine
along with the polymer powder. As is commonly done, it would be
beneficial to add the glass to molten polymer to reduce shear
damage to the hollow spheres. The formulations were sensitive to
residence time in the 19 mm compounder. The material would burn up
almost immediately if it was not constantly moving through the
machine. Extrusion was then completed using a 1 inch single screw
extruder with the 19 mm.times.3 mm die profile. Temperatures
settings were the same as typically used for compounding and
extrusion of THV220A based formulations (185.degree. C. flat
temperature profile for compounding and Barrel-1=180.degree. C.,
Barrel-2=150.degree. C., Barrel-3=150.degree. C., Die=150.degree.
C. for profile extrusion). Processing notes were taken throughout.
ASTM Type-IV dog-bones were cut from the extruded strips and then
tensile tested. The strain was normalized using a 1'' gauge length.
The following data in table 1 captures the results obtained with
the glass sphere/THV composite materials.
TABLE-US-00002 TABLE 2 Example b c D e f THV-220, gms 50.0 55.0
55.0 55.00 55 3M iM30K Glass 50.0 44.5 44.0 43.50 44 Beads, gms
Additive, gms 0.0 0.5 1.0 1.5 1.0 Additive on 0.0 1.0 2.0 3.0 2.0
IM30K, % Density of IM30K, 0.60 0.62 0.62 gm/cc Puck Density 1.33
1.28 1.28 1.11 Extruded, gm/cc Predicted Vol % 47 49 49 65 iM30k
using a Density of 0.65 gm/cc for It Predicted Wgt % 23 25 25 39
iM30k using a Density of 0.65 gm/cc for It Tensile at Yield, Could
6.1 5.1 4.7 5 Mpa not Elongation at extrude 9.8 7.9 7.6 3 Yield, %
Tensile at Break, 6.1 4.8 4.3 2.5 Mpa Elongation at 25 750 (825)
590 (775) 20 (225) Break, %
In sample 3f, two passes were used to attain the desired glass bead
packing level. This approach worked the best to get to the desired
packing levels though potential damage to the glass is a concern.
Samples 3d, 3e, and 3f were also tensile tested at a later date
(approximately two months after being made) without negative
changes to the elongation at break, see parenthesis in the above
table).
[0123] At a volume packing of about 50% glass, a 2% loading of
NZ-12 on the iM30k on the glass resulted in a composite with a high
percentage strain to failure. Interestingly, the strain to failure
of the highly loaded composite (sample 3f at approximately 65
volume % glass beads) exceeded that of a composite sample loaded to
47% glass treated with 1% modifier (sample 3c). See FIG. 3. The
data indicate that the effect of the interfacial modifier is to
increase the elasticity and compatibility of the glass and polymer.
The aforementioned experiments reveal that the interfacial modifier
alters the interfacial strength of the hollow glass spheres and the
fluorocarbon polymer. A loading of 2% is needed at a volumetric
packing level of about 50% to maintain favorable properties. See,
FIG. 5. The results indicate that packing levels greater that 50%
may be attained, but will require higher modifier loading levels to
perform.
Hollow Glass Bubbles in Tire Sidewall Compounds
[0124] The standard tire sidewall rubber compound used in these
experiments were prepared by and obtained from Continental Carbon
Company of Houston, Tex. The hollow glass bubbles, iM30k, were
obtained from 3M. The tire sidewall compound was first banded on a
two roll mill and then the indicated amount of iM30k, either
uncoated or coated, was added and mixed in to form the final
compound. The coated iM30k was easiest to mix in the compound
compared to the uncoated iM30k. The resulting compounds were
evaluated for cure and physical properties according to the ASTM
methods below with the results shown in below.
Cure rheology: Tests were run on uncured, compounded samples using
an Alpha Technologies Moving Die Rheometer (MDR) Model 2000 in
accordance with ASTM D5289-93a at 160 C, no preheat, 12 minutes
elapsed time, and a 0.5 degree arc. Both the minimum torque (M(L))
and highest torque attained during a specified period of time when
no plateau or maximum torque was obtained (M(H)) were measured.
Also measured were the time for the torque to increase 2 units
above M(L) ("t(s)2"), the time for the torque to reach a value
equal to M(L)+0.5(M(H)-M(L)) ("t'50"), and the time for the torque
to reach M(L)+0.9(M(H)-M(L)) ("t'90"). Press-Cure: Sample sheets
measuring 150.times.150.times.2.0 mm were prepared for physical
property determination by pressing at about 6.9 mega Pascal (MPa)
for 10 minutes at 160 C, unless otherwise noted. Physical
properties: Tensile Strength at Break, Elongation at Break, and
Modulus at various elongations were determined using ASTM D412-92
on samples cut from press-cured sheet with ASTM Die D. Units are
reported in MPa. Hardness: Samples were measured using ASTM
D2240-85 Method A with a Type A(2) Shore Durometer. Units are
reported in points on the Shore-A scale. Tear Strength: Tear
strength was determined using ASTM D624-00 on samples cut from the
press-cured sheet with ASTM Die C. The units are reported in
kN/m.
Tire Application
[0125] One aspect of the invention relates to a tire having a tire
portion having a layer containing a composite formed by combining
hollow glass microspheres, a rubber formulation and other
conventional tire compounding components. The tire portion
typically comprises an internal layer of the tire structure. One
important tire structure can comprise is a tire sidewall or a tire
tread portion. We have found that the combination of a hollow glass
microsphere having a coating of an interfacial modifier, a rubber
formulation and conventional tire compounding components can result
in a tire with substantial structural integrity but with reduced
weight. Enhanced fuel efficiency is often obtained from a variety
of wheeled vehicles from physically lighter tires. We have found
that an improved tire can contain an improved tire composition in
the tire bead, sidewall or tread portion comprising a layer or a
zone or a component of the tire comprising a dispersion of a hollow
glass microsphere having an interfacial modifier coating in a tire
rubber formulation. The interfacial modifier used in the improved
tire formulations of the invention improves the association of the
hollow glass microsphere with the rubber compounding formulation.
This close association of a physical nature, that does not involve
coupling or covalent binding, maximizes reduced weight while
avoiding reducing the desirable properties of the rubber
formulation. We have found that reactive or coupling agents that
have the capability of forming covalent bonds with the rubber
components and the hollow glass microspheres are not desirable
since they tend to substantially reduce viscoelastic properties
which in turn can reduce the utility lifetime and other beneficial
aspects of the tire.
[0126] Conventional tire structures have a variety of materials in
a number of forms. Tire tread is made of rubber compositions
containing rubber reinforcing carbon black silica and other
curative or structural materials. The tread material is formed on a
tire carcass comprising flexible but similar rubber compositions in
typically closely associated manufacturing techniques.
[0127] The tire of the invention is an assembly of numerous
components that are built up in manufacturing equipment and then
cured in a press under heat and pressure to form the final tire
structure. Heat facilitates a polymerization reaction that
cross-links rubber formulation into a useful rubber composition.
The cured or volcanic polymers create an elastic quality that
permits the tire to be compressed in an area of road contact but
permit spring back to an original shape at low and high speeds.
Tires are made of a number of individual components that are
assembled into the final structure. The tire inner liner is an
extruded rubber sheet compounded with additives at every level
results in low air permeability. This inner liner ensures that the
rubber tire will maintain high pressure air for extended use
periods. The tire body ply is a calendar to sheet consisting of a
layer of rubber a layer of fabric a second layer of rubber and
other components that provide strength or run-flat capabilities.
Depending on speed and vehicle weight tires can have from 2 to 5 or
more ply layers. The tire sidewall is a non-reinforced rubber
extruded profile. The sidewall formulation provides abrasion
resistance and environmental resistance. The sidewall destabilizes
to heat and oxidation. The tire structure includes high-strength
steel wire encased in a rubber compound to provide mechanical
strength and stability to the tire structure. The apex and bead
structure is a triangular extruded profile providing a cushion
between the rigid bead and the flexible inner liner and body ply
assembly of the tire. Tires typically comprise either a bias or
radial ply belt. Such belts typically comprise calendared sheets
consisting of rubber layers closely spaced steel cords and
additional rubber layers. The belts give the tire strength and
resistance while retaining flexibility. The tread is a thick
extruded profile that surrounds the tire carcass. Tread compounds
include additives to prove or impart wear resistance and traction
in addition to resistance to heat and oxidation. Many tires include
extruded components that can be formed between, for example, the
belt package and the tread to isolate the tread for mechanical wear
from steel belts. Such technology can improve the lifetime of the
tire by isolating internal tire structures. Tire components are
typically made from natural or synthetic rubbers including
polyisoprene or other conventional elastomer materials. The
elastomers include styrene butadiene copolymers polybutadiene
polymers halo-butyl rubbers and others. Tire formulations also
comprise carbon black for reinforcement and abrasion
characteristics, silica, sulfur cross-linking compounds,
vulcanization accelerators activators etc, antioxidants, anti-ozone
compounds and textile and steel fabric and fibers.
[0128] Tire plant processing is traditionally divided into
compounding, component preparation, building and curing.
[0129] Compounding is the operation of bringing together all the
ingredients required to mix a batch of rubber compound. Each
component has a different mix of ingredients according to the
properties required for that component. Mixing is the process of
applying mechanical work to the ingredients in order to blend them
into a homogeneous substance. Internal mixers are often equipped
with two counter-rotating rotors in a large housing that shear the
rubber charge along with the additives. The mixing is done in three
or four stages to incorporate the ingredients in the desired order.
The shearing action generates considerable heat, so both rotors and
housing are water-cooled to maintain a temperature low enough to
assure that vulcanization does not begin.
[0130] After mixing the rubber charge is dropped into a chute and
fed by an extruding screw into a roller die. Alternatively, the
batch can be dropped onto an open rubber mill batchoff system. A
mill consists of twin counter-rotating rolls, one serrated, that
provide additional mechanical working to the rubber and produce a
thick rubber sheet. The sheet is pulled off the rollers in the form
of a strip. The strip is cooled, dusted with talc, and laid down
into a pallet bin. The ideal compound at this point would have a
highly uniform material dispersion; however in practice there is
considerable non-uniformity to the dispersion. This is due to
several causes, including hot and cold spots in the mixer housing
and rotors, excessive rotor clearance, rotor wear, and poorly
circulating flow paths. As a result, there can be a little more
carbon black here, and a little less there, along with a few clumps
of carbon black elsewhere, that are not well mixed with the rubber
or the additives.
[0131] In tire compounding processes, the down or rubber material
is typically added to a mixing apparatus, mixing is initiated and
the powdered components are blended into the rubber. We have found
that incorporating hollow glass spheres into the rubber alone or
with conventional powdered components is difficult. The low density
and fine character of the hollow glass along with the difference in
surface character between the glass and the rubber prevent the
ready incorporation of powder hollow glass spheres into the rubber
material. We have found that for uncoated hollow glass spheres that
the low density glass with or without other powdered components can
be first added to a mixer, followed by the more rubber portion.
This order of addition can result in successful incorporation of
materials into the rubber formulation. In the instance that
conventional compounding techniques are to be followed in
manufacturing tire formulations using hollow glass spheres, we have
found that conventional processes can be used, surprisingly, if the
hollow glass spheres are pretreated with an effective amount of the
interface modifier. In such a process, effective amount of the
interface modifier comprising is formed in a coating on the surface
of the hollow glass spheres. This pre-coating step permits the
ready incorporation of glass particles into the rubber formulation
alone or in combination with other powdered components.
[0132] Components fall into three classes based on manufacturing
process--calendaring, extrusion, and bead building. The extruder
machine consists of a screw and barrel, screw drive, heaters, and a
die. The extruder applies two conditions to the compound: heat and
pressure. The extruder screw also provides for additional mixing of
the compound through the shearing action of the screw. The compound
is pushed through a die, after which the extruded profile is
vulcanized in a continuous oven, cooled to terminate the
vulcanization process, and either rolled up on a spool or cut to
length. Tire treads are often extruded with four components in a
quadraplex extruder, one with four screws processing four different
compounds, usually a base compound, core compound, tread compound,
and wing compound. Extrusion is also used for sidewall profiles and
inner liners. The calender is a series of hard pressure rollers at
the end of a process. Fabric calenders produce an upper and lower
rubber sheet with a layer of fabric in between. Steel calenders do
so with steel cords. Calenders are used to produce body plies and
belts. A creel room is a facility that houses hundreds of fabric or
wire spools that are fed into the calender. Calenders utilize
downstream equipment for shearing and splicing calendered
components.
[0133] Tire building is the process of assembling all the
components onto a tire building drum. Tire-building machines (TBM)
can be manually operated or fully automatic. Typical TBM operations
include the first-stage operation, where inner liner, body plies,
and sidewalls are wrapped around the drum, the beads are placed,
and the assembly turned up over the bead. In the second stage
operation the belt package and tread are applied and the green tire
is inflated and shaped. All components require splicing. Inner
liner and body plies are spliced with a square-ended overlap. Tread
and sidewall are joined with a skived splice, where the joining
ends are bevel-cut. Belts are spliced end to end with no overlap.
Splices that are too heavy or non-symmetrical will generate defects
in force variation, balance, or bulge parameters. Splices that are
too light or open can lead to visual defects and in some cases tire
failure. The final product of the TBM process is called a green
tire, where green refers to the uncured state.
[0134] Curing is the process of applying pressure to the green tire
in a mold in order to give it its final shape, and applying heat
energy to stimulate the chemical reaction between the rubber and
other materials. In this process the green tire is automatically
transferred onto the lower mold bead seat, a rubber bladder is
inserted into the green tire, and the mold closes while the bladder
inflates. As the mold closes and is locked, the bladder pressure
increases so as to make the green tire flow into the mold, taking
on the tread pattern and sidewall lettering engraved into the mold.
The bladder is filled with a recirculating heat transfer medium,
such as steam, hot water, or inert gas. Temperatures are in the
area of 350.+-.40 degrees Fahrenheit with pressures around
350.+-.25 PSI for curing. Passenger tires cure in approximately 15
minutes. At the end of cure the pressure is bled down, the mold
opened, and the tire stripped out of the mold. The tire may be
placed on a PCI, or post-cure inflator, that will hold the tire
fully inflated while it cools. There are two generic curing press
types, mechanical and hydraulic. Mechanical presses hold the mold
closed via toggle linkages, while hydraulic presses use hydraulic
oil as the prime mover for machine motion, and lock the mold with a
breech-lock mechanism.
[0135] In such a structure, the glass microsphere and rubber
elastomer composition of the invention can be used in a variety of
the tire components. Preferably the compositions of the invention
are used as an internal component for making the tire carcass,
sidewall or under tread component.
[0136] Conventional rubber tire formulations were prepared
containing glass microsphere and made into tire sidewall
structures. The interface allows our coatings enable the smooth
incorporation of the glass bubbles into the tire formulation and
obtained as to reduce weight without compromising structural
integrity. Our data is as follows:
Evaluation of Glass Bubbles in a Tire Sidewall Formulation
Hollow Glass Bubbles in Tire Sidewall Compounds
[0137] The standard tire sidewall rubber compound used in these
experiments were prepared by and obtained from Continental Carbon
Company of Houston, Tex. The hollow glass bubbles, iM30k, were
obtained from 3M. The tire sidewall compound was first banded on a
two roll mill and then the indicated amount of iM30k, either
uncoated or coated, was added and mixed in to form the final
compound. The coated iM30k was easiest to mix in the compound
compared to the uncoated iM30k. The resulting compounds were
evaluated for cure and physical properties according to the ASTM
methods below with the results shown in Table 2.
Cure rheology: Tests were run on uncured, compounded samples using
an Alpha Technologies Moving Die Rheometer (MDR) Model 2000 in
accordance with ASTM D5289-93a at 160 C, no preheat, 12 minutes
elapsed time, and a 0.5 degree arc. Both the minimum torque (M(L))
and highest torque attained during a specified period of time when
no plateau or maximum torque was obtained (M(H)) were measured.
Also measured were the time for the torque to increase 2 units
above M(L) ("t(s)2"), the time for the torque to reach a value
equal to M(L)+0.5(M(H)-M(L)) ("t'50"), and the time for the torque
to reach M(L)+0.9(M(H)-M(L)) ("t'90"). Press-Cure: Sample sheets
measuring 150.times.150.times.2.0 mm were prepared for physical
property determination by pressing at about 6.9 mega Pascal (MPa)
for 10 minutes at 160 C, unless otherwise noted. Physical
properties: Tensile Strength at Break, Elongation at Break, and
Modulus at various elongations were determined using ASTM D412-92
on samples cut from press-cured sheet with ASTM Die D. Units are
reported in MPa. Hardness: Samples were measured using ASTM
D2240-85 Method A with a Type A(2) Shore Durometer. Units are
reported in points on the Shore-A scale. Tear Strength: Tear
strength was determined using ASTM D624-00 on samples cut from the
press-cured sheet with ASTM Die C. The units are reported in
kN/m.
Tire Application
[0138] One aspect of the invention relates to a tire having a tire
portion having a layer containing a composite formed by combining
hollow glass microspheres, a rubber formulation and other
conventional tire compounding components. The tire portion
typically comprises an internal layer of the tire structure. One
important tire structure can comprise is a tire sidewall or a tire
tread portion. We have found that the combination of a hollow glass
microsphere having a coating of an interfacial modifier, a rubber
formulation and conventional tire compounding components can result
in a tire with substantial structural integrity but with reduced
weight. Enhanced fuel efficiency is often obtained from a variety
of wheeled vehicles from physically lighter tires. We have found
that an improved tire can contain a tire portion in the tire bead,
sidewall or tread portion comprising a layer or a zone or a
component of the tire comprising a dispersion of a hollow glass
microsphere having an interfacial modifier coating in a tire rubber
formulation. The interfacial modifier used in the improved tire
formulations of the invention improves the association of the
hollow glass microsphere with the rubber compounding formulation.
This close association of a physical nature, that does not involve
coupling or covalent binding, maximizes the reduced weight while
avoiding the desirable properties of the rubber formulation. We
have found that reactive or coupling agents that have the
capability of forming covalent bonds with the rubber components and
the hollow glass microspheres are not desirable since they tend to
substantially reduce viscoelastic properties, which in turn can
reduce the utility lifetime and other beneficial aspects of the
tire.
[0139] Tire plant processing is traditionally divided into
compounding, component preparation, building and curing. In tire
compounding processes, the rubber material is typically added to a
mixing apparatus, mixing is initiated and the powdered components
are blended into the rubber. We have found that incorporating
hollow glass spheres into the rubber alone or with conventional
powdered components is difficult. The low density and fine
character of the hollow glass along with the difference in surface
character between the glass and the rubber prevent the ready
incorporation of powder hollow glass spheres into the rubber
material. We have found that for uncoated hollow glass spheres that
the low density glass with or without other powdered components can
be first added to a mixer, followed by the more rubber portion.
This order of addition can result in successful incorporation of
materials into the rubber formulation. In the instance that
conventional compounding techniques are to be followed in
manufacturing tire formulations, using hollow glass spheres, we
have found that conventional processes can be used, surprisingly,
if the hollow glass spheres are pretreated with an effective amount
of the interface modifier. In such a process, effective amount of
the interface modifier comprising about 0.005 to 8.0 weight percent
of the interfacial modifier is formed in a coating on the surface
of the hollow glass spheres. This pre-coating step permits the
ready incorporation of our particles into the rubber formulation
alone or in combination with other powdered components.
[0140] In the tire building process, where the various components
of tire manufacturing and tire materials are brought together, the
glass microsphere and rubber elastomer composition of the invention
can be used in a variety of the tire components. Preferably the
compositions of the invention are used as an internal component for
making the tire carcass, sidewall or under tread component.
[0141] Conventional rubber tire formulations were prepared
containing glass microsphere and made into tire sidewall
structures. The interface allows our coatings enable the smooth
incorporation of the glass bubbles into the tire formulation and
obtained as to reduce weight without compromising structural
integrity.
Internal Mixing Study of the Tire Sidewall Compound Containing
Glass Bubbles
Procedure and Test Methods
[0142] The standard tire sidewall rubber compound used in these
experiments were prepared by and obtained from Continental Carbon
Company of Houston, Tex. One compound contained 50 phr carbon black
and the other 5 phr. The hollow glass bubbles, iM30k, were obtained
from 3M. The tire sidewall compound was first banded on a two roll
mill and then the indicated amount of iM30k or 5000, either
uncoated or coated, was added and mixed in to form the final
compound. The coated iM30k was easiest to mix in the compound
compared to the uncoated iM30k. The resulting compounds were
evaluated for cure and physical properties according to the ASTM
methods below.
Cure rheology: Tests were run on uncured, compounded samples using
an Alpha Technologies Moving Die Rheometer (MDR) Model 2000 in
accordance with ASTM D5289-93a at 160.degree. C., no preheat, 12
minutes elapsed time, and a 0.5 degree arc. Both the minimum torque
(M(L)) and highest torque attained during a specified period of
time when no plateau or maximum torque was obtained (M(H)) were
measured. Also measured were the time for the torque to increase 2
units above M(L) ("t(s)2"), the time for the torque to reach a
value equal to M(L)+0.5(M(H)-M(L)) ("t'50"), and the time for the
torque to reach M(L)+0.9(M(H)-M(L)) ("t'90"). Mooney Scorch: Tests
were run on uncured, compounded samples in accordance with ASTM
D1646-06. Press-Cure: Sample sheets measuring
150.times.150.times.2.0 mm were prepared for physical property
determination by pressing at about 6.9 mega Pascal (MPa) for 10
minutes at 160.degree. C. Physical properties: Tensile Strength at
Break, Elongation at Break, and Modulus at various elongations were
determined using ASTM D412-92 on samples cut from press-cured sheet
with ASTM Die D. Units are reported in MPa. Hardness: Samples were
measured using ASTM D2240-85 Method A with a Type A(2) Shore
Durometer. Units are reported in points on the Shore-A scale. Tear
Strength: Tear strength was determined using ASTM D624-00 on
samples cut from the press-cured sheet with ASTM Die C. The units
are reported in kN/m.
[0143] All of the tire sidewall compounds shown in Table 4 were
mixed in a standard Farrel laboratory BR banbury. A conventional
2-pass mix was employed. The first pass (with all the ingredients
except for the accelerator and sulfur) was discharged at
160.degree. C., while the second pass (with the accelerator and
sulfur) was discharged at 100.degree. C. At first a conventional
mix, which involves adding the polymer to the banbury and then the
dries, did not work when attempting to make the compound containing
60 phr uncoated iM30K. The compound would not come together. An
upside down mix, which involves adding the dries to the banbury
first and then the polymer, was then tried. Compounds containing 30
and 60 phr of uncoated and IM coated iM30K were mixed using this
method. A compound containing 60 phr of IM coated iM30K was also
mixed the conventional way and was successful.
Standard Tire Sidewall Formulations Containing Glass Spheres
TABLE-US-00003 [0144] TABLE 3 Compound # Ingredient, phr 1 (a) 2
(b) 3 (b) 4 (b) 5 (b) 6 (a) 7(c) SVR-3L 50 50 50 50 50 50 50
Taktene 1203 50 50 50 50 50 50 50 N 330 50 50 50 50 50 50 50 iM30K
30 60 iM30K + 5.4 phr KR 9S 32 63.2 63.2 63.2 Calsol 510 10 10 10
10 10 10 10 Stearic Acid 2 2 2 2 2 2 2 Sunolite 240 1 1 1 1 1 1 1
Santoflex 13 4 4 4 4 4 4 4 Wingstay 100 1 1 1 1 1 1 1 Zinc Oxide 3
3 3 3 3 3 3 TBBS 1 1 1 1 1 1 1 Sulfur 1.8 1.8 1.8 1.8 1.8 1.8 1.8
Formula Weight 173.8 203.8 205.8 233.8 237 237 237 Mix Time (1st
Pass), mm, ss 3:22 2:10 2:15 3:10 2:00 2:40 NA Power (1st Pass),
KWH 0.410 0.296 0.338 0.305 0.258 0.267 NA MDR @ 160.degree. C.,
0.5.degree. Arc, 100 cpm, for 12 minutes ML, in-lb 1.81 2.78 3.00
3.81 4.38 4.54 1.74 MH, in-lb 13.37 18.13 18.63 20.68 22.53 22.97
15.83 .DELTA.T, in-lb 11.56 15.35 15.63 16.87 18.15 18.43 14.09
ts2, minutes 2.94 1.95 2.19 1.72 1.97 2.00 2.60 t'50, minutes 3.59
2.43 2.84 2.16 2.66 2.78 3.54 t'90, minutes 5.40 3.32 4.48 2.74
4.24 4.48 5.72 Mooney Scorch MS 1 + 30 @121.degree. C. Initial
Viscosity, MU 23.3 56.7 51.1 56.6 61.7 61.7 30.7 Minimum Viscosity,
MU 14.8 27.9 28.0 30.9 37.5 39.6 19.0 t3, minutes 30.2 20.8 23.1
18.5 20.1 20.3 30.1 t10, minutes 23.0 25.6 21.0 22.6 23.0 t18,
minutes 24.0 26.8 22.0 23.8 24.2 Physical Properties after Press
Cure for 12 minutes @ 160.degree. C., Die D Tensile, psi 3080 1662
1745 1098 1092 1017 763 50% Modulus, psi 160 175 203 196 223 186
160 100% Modulus, psi 260 220 242 208 237 197 165 200% Modulus, psi
UN 408 460 339 371 310 250 Elongation, % 510 458 455 405 422 460
425 Shore A2 Hardness 54 59 61 66 69 71 64 Die C Tear, lbf/in 320
133 147 100 119 111 101 Density, g/cc 1.099 1.007 1.003 0.934 0.953
0.927 0.962 Density Reduction, % -- 8.4 8.7 15.0 13.3 15.7 12.5
Theo Density (% Breakage) 0.984(12) 0.983(11) 0.915(10.6)
0.915(16.4) 0.915(6.6) 0.915(16.6) (a)Conventional Mix (b)upside
down mix. (c) iM30K + 6 phr KR9S added to AW1 on open mill
[0145] Modified glass bubbles incorporated easier into the
compounds than the uncoated glass bubbles as determined by time and
power to mix (compare 1a to the other compounds). In addition to
benefits in time and power, only interfacially modified glass
bubbles could be incorporated into the tire formulations using a
conventional mixing method; when unmodified, the glass bubbles had
to be mixed via an upside down method. As expected, using an upside
down method increased glass breakage. Lastly, adding the glass
bubbles with the other ingredients improves the physical
properties.
Glass Beads and Hollow Sphere Study
[0146] Solid glass beads were acquired. Bead sizes were selected
based upon packing theory of solid spherical particles. Ultimate
packing behavior of hollow glass spheres is limited by the narrow
size distribution of the hollow glass spheres. The beads were
interfacially modified and used as a proxy for hollow glass bubbles
due to the wider size availability of beads to that of bubbles. In
order show increased packing level, two sized solid glass beads
were purchased and used to determine powder packing behavior. The
results are shown in Table 5 below.
TABLE-US-00004 TABLE 5 Amount of Packing Size Amount of Coatng
Density Packing Bubble Bead G/cc .mu. Each Size Coating (%) (g/cc)
% 5000 2.43 11 100 none 0 1.573 63 5000 2.4 11 100 IM3 1.8 1.806 75
2429 2.43 85 100 none 0 1.480 59 2429/5000 2.43 85/11 75/25 none 0
1.866 75 2429/5000 2.43 85/11 75/25 IM1 2 1.982 83 2429/5000 2.40
85/11 75/25 IM3 1.8 1.951 80 iM30K 0.60 16 100 none 0 0.374 62
iM30K 0.615 16 100 IM3 5.4 0.422 69 iM30K 0.605 16 100 IM3 1.8
0.416 69 iM30K 0.608 16 100 IM4 3 0.406 67 iM30K 0.615 16 100 IM5
5.4 0.426 69 iM30K 0.613 16 100 IM6 4.8 0.431 70
[0147] It is clear that the use of the different size glass
particles increases packing density. The findings here can be used
to increase ultimate glass bubble loading in a continuous phase if
different sized hollow glass bubble sizes were made and blended.
Further hollow glass bubble loading levels will be attainable that
can reduce sidewall specific gravity to levels less than what has
been done at this time. Also note the increased packing density of
interfacially modified hollow glass spheres over that of unmodified
glass bubbles.
Thermal Conductivity within a Thermoplastic
[0148] Thermal conductivity testing of hollow glass bubble filled
nylon vs. unfilled nylon was conducted. Samples consisted of 50
volume % 3M K1 hollow glass spheres in a H.B. Fuller Co. nylon
(polyamide) blend.
[0149] Testing was completed on using a Mathis TC-30 thermal
conductometer which uses a modified hot wire technique. The
unfilled resin sample measured at 0.23+/-0.01 W-K.sup.-1 m.sup.-1.
The microsphere-filled sample measured at 0.11+/-0.01 W-K.sup.-1
m.sup.-1. The reduction, from the use of hollow glass spheres in
the polymer composite, in thermal conductivity was 52%. Delrin was
used as the reference material for a control. The reference was
measured at its accepted thermal conductivity value of 0.38
W-K.sup.-1 m.sup.-1.
Rheological Benefits of Using Spherical Particles with Irregularly
Shaped Particles
[0150] Additionally, using spherical particles enhanced rheological
properties in the composite. Rough particles (TDI tungsten) and
smooth particles (Ervin Industries S70 carbon steel) were
interfacially modified. The particles were incorporated into a
Dyneon PVDF 11008 polymer using three ratios of spherical to rough
particles within a 19 mm B&P twin screw compounder. The ratios
were (1) all rough; (2) 50/50 volume % spherical: rough or (3) all
spherical. For each particle ratio, the volumetric particulate
loading level within the polymer phase was systematically increased
until over-torque occurred. Melt temperature, torque, and pressure
were recorded.
[0151] The presence of spherical particles enhanced rheological
properties shown in FIG. 5. When comparing rough and the 50/50
blended particles, the spherical particles lowered melt temperature
at a given particle loading and also allowed for higher overall
particle loadings before over-torque occurred. While compounding
entirely spherical particles, the compounder continued to run at
all particulate loading levels, without over torque, at all
volumetric loading levels evaluated. The enhanced rheological
properties of the 50/50 blended particles over that of the
spherical particles at loading levels above that where the rough
particles over-torqued the machine was unexpected.
[0152] 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 Scotchbright.RTM. pads for cleaning surfaces, brake pads
(aluminum oxide or garnet), apex seals for Wankel.RTM. or rotary
engines, fuel applications (line, tank or seal), engine or drive
train counterweight, automotive or truck wheel weight.
[0153] An inorganic hollow glass sphere, ceramic, nonmetal or
mineral particle polymer composite can be made comprising the
hollow glass and ceramic, inorganic, nonmetal or mineral particle,
the majority of the particles having a particle size greater than
about 5 microns. We believe an interfacial modifier (IM) 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 an IM
coating can have a thickness of about 0.10 to 1 microns.
[0154] The density of the composite can be about 0.2 to 5
gm-cm.sup.-3, 0.2 to 2 gm-cm.sup.-3, 0.2 to 0.8 gm-cm.sup.-3. The
composite can comprise a polymer phase and a particle coating
comprising an interfacial modifier. The composite has a tensile
strength of about 0.1 to 15 times, about 0.1 to 5 times, about 0.2
to 10 times, about 0.3 to 10 times that of the base polymer and a
tensile elongation of about 5% and 100% of base polymer and can
comprise an inorganic nonmetal particle, the majority of the
particles having a particle size of about 5 to 1000 microns in a
polymer such as a thermoplastic including a polyolefin (and a
HDPE), a PVC, or fluoropolymer phase. The composite can have a
tensile strength of greater than about 2 MPa with a particle
morphology of the particulate of 1 to 10.sup.6 and the circularity
of the particulate is 12.5 to 25 or 13 to 20. Alternatively, the
composite has a tensile strength of greater than about 2 MPa and
the non-metal, inorganic or mineral particle comprises a particle
morphology of the particulate of 1 to 10.sup.6 and a circularity of
13 to 20. The composite has a tensile strength of about 0.1 to 10
times that of the base polymer and a tensile elongation of about
10% and 100% of base polymer. The composite has a tensile strength
of about 0.1 to 5 time that of the base polymer and a tensile
elongation of about 15% and 100% of base polymer. The particle
comprises a mineral having a particle size (P.sub.s) of about 15 to
1200 microns, a ceramic having a particle size (P.sub.s) of greater
than about 10 microns, a solid glass sphere having a particle size
(P.sub.s) of about 15 to 250 microns, a silica sand or zirconium
silicate having a particle size (P.sub.s) of about 75 to 300
microns, an aluminum oxide, a garnet, or other particulate.
[0155] 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, a polyolefin
(including a high density polyolefin) such as a polyethylene
(including a HDPE) a polypropylene 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.-%.
[0156] The resulting composite has a thermoplastic shear of at
least 5 sec.sup.-1, a density is less than 0.9 gm-cm.sup.-3, a
density is about 0.2 to 1.4 gm-cm.sup.-3.
[0157] In preferred tire formulations the composite comprises a
synthetic rubber polymer. The particle comprises a mixture of
particles derived from two distinct nonmetallic particulate
compositions.
[0158] The particle comprises a mixture of at least one nonmetallic
particulate composition and at least one metallic particulate
composition. The composite particle can comprise a coating of about
0.005 to 8 wt % of an interfacial modifier, based on the
composite.
[0159] The component can comprise a fishing lure or jig, an
abrasive pad, that can be made comprising cleaning materials, a
brake pad, a fuel component comprising a line a tank or seal, a
drive train counterweight, an automotive, truck, wheel weight.
[0160] The composites materials of the invention can comprise a
hollow glass microsphere and polymer composite that includes about
30 to 87 volume percent of a hollow glass microsphere having a
particle size greater than about 5.mu. and having a coating of
about 0.005 to 5 weight percent of interfacial modifier. The
composite also includes a polymer phase, the polymer can have a
density of greater than 17 gm-cm.sup.-3. The composite can have a
composite density that is about 0.4 to 5 gm-cm.sup.-3 about 0.4 to
2 gm-cm.sup.-3 or about 0.4 to 0.8 gm-cm.sup.-3. The composite can
have a tensile strength of about 2 to 30 times that of the base
polymer, a tensile elongation of about 5% to 100% of the base
polymer or about 20% to 100% of the base polymer. Further the
composite can have a tensile strength of about 10 to 20 times that
of the base polymer in a tensile elongation of about 15% to 90% of
the base polymer. When extruded, the composite has a thermoplastic
shear of at least about 5 or 15 sec.sup.-1 and can have a tensile
strength of at least about 0.2 or 1.0 Mpa. Additionally the
composite can comprise a packing extent that is greater than about
30 volume percent or about 50 volume percent of the composite. The
hollow glass microsphere in the composite has a particle size
distribution that includes particles having a particle size Ps
between about 10 to 1000 microns, alternately about 10 to 300.mu..
and more specifically about 10 to 200. The composite the invention,
in combination with a hollow glass microsphere can have a second
particulate having a particle size that differs from the
microsphere by at least 5.mu.. Similarly the composite can have a
hollow glass microsphere and a second particle such that the
particle size is defined by the formula P.sub.S.gtoreq.2
P.sub.S.sup.1 or P.sub.S.ltoreq.0.05 P.sub.S.sup.1 wherein P.sub.S
is the particle size of the hollow glass microsphere and
P.sub.S.sup.1 is the particle size of the particulate. The
composite particulate, apart from the hollow glass microsphere can
comprise virtually any other particle having a particle size that
ranges from about 10 to about 1000.mu.. Such particles can include
a metallic particulate a solid glass sphere a second hollow glass
microsphere, and inorganic mineral, a ceramic particle or mixtures
thereof. While hollow glass spheres have a circularity of less than
15 indicating a substantially circular particle, other particulate
materials of the invention using the composite can have a
circularity showing a rough or amorphous particle character with a
circularity greater than 12.5. Polymers used in the compositions of
the invention include a variety of thermoplastic materials
including a polyamide, such as a nylon, poly(ethylene-co-vinyl
acetate), a natural or synthetic rubber, polyvinyl chloride, a
fluoro-polymer, or fluoroelastomer. The composite can have a
particle with greater than 5 vol-% of a particle having a particle
size P.sub.S distribution ranging from about 10 to about 200
microns and greater than 10 vol-% of a particulate in the range of
about 5 to 1000 microns. The particles can be a mixture of
particles of differing nonmetallic composition. The composite
comprises about 0.01 to 4 wt % of an interfacial modifier. The
composite additionally comprises an organic or inorganic pigment or
an organic fluorescent dye.
[0161] A hollow glass microsphere and polymer composite can
comprise about 90 to 30 volume-% of a hollow glass microsphere
having a density greater than 0.10 gm-cm.sup.-3 and less than 5
gm-cm.sup.-3 and a particle size greater than 8 microns; and about
10 to 70 volume-% of a polymer phase;
wherein the microsphere has a coating comprising about 0.005 to 8
wt.-% of an interfacial modifier; and wherein the composite density
is about 0.4 to 15 gm-cm.sup.-3. The density can be about 0.4 to 5
gm-cm.sup.-3 about 0.4 to 2 gm-cm.sup.-3 or about 0.4 to 0.8
gm-cm.sup.-3
[0162] A shaped article comprising the composite comprises about 87
to 50 vol-% of a hollow glass microsphere, and having a particle
size distribution having at least 10 wt.-% of a particulate within
about 10 to 100 microns and at least 10 wt.-% of the polymer
particulate within about 100 to 500 microns and for certain uses
can have a density of about 0.4 to 0.8 gm-cm.sup.-3. Such uses
include an insulating layer comprising the composite of claim 1
wherein the thermal transfer rate of the composite layer is less
than 50% of the thermal transfer rate of a conventional polymer
composite layer, a sealant layer that can be used in an insulated
glass unit, an acoustically insulating layer having a reduced sound
transfer rate, a protective layer having improved impact resistance
comprising the composite layer(s) that after impact rebounds a
structural member used in a structure assembled using a fastener,
wherein the structural member has an improved fastener retention, a
barrier layer, acting as a barrier to gas mass transfer, the
barrier layer, wherein the permeability of the layer to argon,
nitrogen, or a mixed gas having a major proportion of nitrogen is
reduced by at least 50%.
[0163] The composite can be used in a tire composition or
formulation comprising a vulcanizable rubber about 30 to 87 vol %
of a hollow glass microsphere having a coating of about 0.005 to 8
wt. % an interfacial modifier. Such composition can be made with a
process of compounding a tire rubber formulation, the method
comprising adding about 30 to 80 vol % of a hollow glass
microsphere having a coating of about 0.005 to 8 wt. % of an
interfacial modifier, to a tire formulations compounding mixer
containing a un-vulcanized rubber.
[0164] 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.
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