U.S. patent application number 14/410828 was filed with the patent office on 2015-08-06 for process for manufacturing coated filler particle.
The applicant listed for this patent is E.I. DU PONT DE NEMOURS AND COMPANY. Invention is credited to Clyde Spencer Hutchins, Christopher P. Karwas, Jeffrey Michael Rose, Timothy Scott Wyant.
Application Number | 20150218343 14/410828 |
Document ID | / |
Family ID | 48790666 |
Filed Date | 2015-08-06 |
United States Patent
Application |
20150218343 |
Kind Code |
A1 |
Rose; Jeffrey Michael ; et
al. |
August 6, 2015 |
PROCESS FOR MANUFACTURING COATED FILLER PARTICLE
Abstract
The invention pertains to filler modified with functional
particles in a high energy dry-blending process through collisions
of sufficient energy to bound, adhere, or otherwise associate the
pigment particles to the filler.
Inventors: |
Rose; Jeffrey Michael;
(Amherst, NY) ; Hutchins; Clyde Spencer; (Colden,
NY) ; Wyant; Timothy Scott; (Cheektowaga, NY)
; Karwas; Christopher P.; (Lake View, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
E.I. DU PONT DE NEMOURS AND COMPANY |
Wilmington |
DE |
US |
|
|
Family ID: |
48790666 |
Appl. No.: |
14/410828 |
Filed: |
July 1, 2013 |
PCT Filed: |
July 1, 2013 |
PCT NO: |
PCT/US13/48843 |
371 Date: |
December 23, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61667143 |
Jul 2, 2012 |
|
|
|
Current U.S.
Class: |
106/712 ;
106/410; 106/440; 106/457; 106/459; 106/474; 106/483; 106/496;
106/497 |
Current CPC
Class: |
C01P 2006/22 20130101;
C08K 9/12 20130101; C09C 1/40 20130101; C01P 2006/12 20130101; C01P
2004/62 20130101; C09C 1/24 20130101; C09C 1/48 20130101; C01P
2004/03 20130101; C08K 9/02 20130101; C08K 5/3437 20130101 |
International
Class: |
C08K 5/3437 20060101
C08K005/3437; C08K 3/22 20060101 C08K003/22; C08K 9/02 20060101
C08K009/02; C08K 5/23 20060101 C08K005/23; C08K 3/00 20060101
C08K003/00; C08K 5/3417 20060101 C08K005/3417; C08K 3/04 20060101
C08K003/04 |
Claims
1. A modified filler particle comprising a filler particle modified
with discrete functional particles that are sufficiently bound,
adhered, or otherwise associated to the filler such that they are
able to remain associated during subsequent manufacturing
steps.
2. The modified filler particle of claim 1 wherein the discreet
functional particles are pigment particles.
3. The modified filler particle of claim 2 wherein the particle
size distribution for the filler is in a range from 0.1 microns to
100 microns.
4. The modified filler particle of claim 2 wherein the particle
size distribution for the pigment particles is from 0.005 microns
to 4 microns.
5. The modified filler particle of claim 2 wherein the particle
size distribution for the pigment particles is from 0.1 to 3
microns.
6. The modified filler particle of claim 2 wherein the particle
size distribution for the filler is in a range from 10 to 50
microns and the particle size distribution for the pigment
particles is in a range from 0.01 to 3 microns.
7. The modified filler particle of claim 1 wherein the filler
particle is modified with discrete functional particles that impart
an energy absorption function, the discrete functional particles
selected from the group consisting of a) UV absorption modifiers,
b) IR absorption modifiers, c) radiofrequency wave absorption
modifiers, d) fluorescent response modifiers, e) phosphorescent
response modifiers, f) thermochromism modifiers, g) phase-change
modifiers, or h) any combination thereof.
8. The modified filler particle of claim 1 wherein the filler
particle is modified with discrete functional particles that impart
a mechanical property function, the discrete functional particles
selected from the group consisting of a) surface hardness
modifiers, b) lubricity modifiers, c) strength modifiers, d)
toughness modifiers, e) impact resistance modifiers, f) scratch
resistance modifiers, g) mar resistance modifiers, or h) any
combination thereof.
9. The modified filler particle of claim 1 wherein the filler
particle is modified with discrete functional particles that modify
the surface of the filler particle, the discrete functional
particles selected from the group consisting of a) stain resistance
modifiers, b) lubricity modifiers, c) adhesion modifiers of filler
to surrounding medium, d) absorbability modifiers, e) flame
retardants, f) antimicrobial agents, g) modifiers of
self-cleanability h) modifiers of self-healing of a polymeric
matrix comprising the modified filler particle, i) acidity or
alkalinity modifiers, j) modifiers of electrical characteristics,
k) modifiers of magnetic properties, or l) any combination
thereof.
10. The modified filler particle of claim 1 wherein the filler
particle is modified with discrete functional particles that impart
a fluid characteristics change to a medium when the modified filler
particle is added to said medium, the discrete functional particles
selected from the group consisting of a) surface tension modifiers,
b) rheology modifiers, c) modifiers of the agglomeration state of
the modified filler particle, d) modifiers of the packing
efficiency of the modified filler particle, e) compatibilizers, f)
dispersants, or g) any combination thereof.
Description
BACKGROUND OF THE INVENTION
[0001] In general, filled polymer materials are desirable for use
in a variety of applications, such as consumer products and polymer
composite building materials. Filled polymer materials often employ
colorants to improve the appearance and aesthetic character of the
objects into which they are formed. Typically, pigments or dyes are
added to the polymer before it is blended with the filler. However,
colored filled polymer materials are known to fade and undergo
aesthetically displeasing color changes. One form of aesthetically
displeasing color change is known as "whitening". When objects
formed from colored filled polymer materials are exposed to
physical damage, such as scratching, impact, and bending, they are
known to change to a white color. The typical mineral fillers that
are used are white in color and it is generally understood that the
whitening is a result of the white filler becoming exposed at the
surface of the object.
[0002] In U.S. Pat. No. 7,863,369 Bianchi et al disclose a colored
filled polymer material formed of a polymer matrix and a pigment.
The pigment includes alumina hydrate particulate having a dye
covalently bonded to the surface of the alumina hydrate
particulate. However, materials made according to the disclosure of
Bianchi are known to blotch and whiten to an unacceptable
degree.
[0003] Accordingly, there is a continued need within the industry
to provide colored filled polymer materials having improved
resistance to whitening due to physical damage.
[0004] In addition, dispersion of traditional pigments with polymer
materials is difficult. Poor dispersion leads to swirling and color
variability with the colored polymer material. Further, poor
dispersion of the pigment within the plastic article may lead to
undesirable mechanical properties. As such, compatibilizers are
typically used to disperse pigment within a polymer material. Such
compatibilizers include a variety of organic compounds that aid in
dispersing the pigment. However, compatibilizers typically are
expensive and may also negatively influence mechanical properties
of the filled polymer material. In addition, pigments are dispersed
in liquid prepolymer mixture using high shear mechanical processes
which negatively impact the prepolymer and require the prepolymer
mixture to be deaerated.
[0005] In Japanese Patent Application Publication Number
1987030133(A), Kaide discloses a colored resin composite made from
abundant blending of colorant with a hydrate of metal oxide
beforehand, from which damaged parts do not experience a whitening
phenomenon. However, Kaide discloses a colored hydrate of a metal
oxide that is blended with a high molecular weight plastic or
rubber material to yield a composite. The present invention is a
filler modified with particles with an association that is strong
enough to withstand subsequent processing, in particular suspension
and mixing in a polar liquid medium (e.g. methyl methacrylate). A
polar liquid media provides a more aggressive environment than the
one disclosed in Kaide, and therefore a more challenging one for
modified filler to persist.
[0006] Accordingly, there is a continued need within the industry
for improved dispersion of colorants and fillers in filled polymer
materials wherein the filler and modifying materials will withstand
processing forces.
FIELD OF THE INVENTION
[0007] The present invention is related to filler material for
polymer composites.
SUMMARY OF THE INVENTION
[0008] One embodiment of the invention is a modified filler
particle comprising a filler particle modified with discrete
functional particles that are sufficiently bound, adhered, or
otherwise associated to the filler such that they are able to
remain associated during subsequent manufacturing steps.
[0009] Another embodiment of the invention is a modified filler
particle comprising a filler particle modified with pigment
particles that are sufficiently bound, adhered, or otherwise
associated to the filler such that they are able to remain
associated during subsequent manufacturing steps.
[0010] Another embodiment of the invention is a filled polymeric
material comprising polymer at least partially filled with filler
particles that are modified with functional particles by blending
them in a blending process wherein the collisions are of sufficient
energy to bound, adhere, or otherwise associate the functional
particles to the filler.
BRIEF DESCRIPTION OF FIGURES
[0011] FIG. 1 shows SEM micrographs comparing unmodified ATH and
ATH modified with various pigments.
[0012] FIG. 2 shows SEM micrographs comparing unmodified ATH, iron
oxide black pigment, and ATH modified with iron oxide black pigment
via dry-blending.
[0013] FIG. 3 shows SEM micrographs comparing unmodified ATH,
carbon black pigment, and ATH modified with carbon black pigment
via shaking.
[0014] FIG. 4 shows SEM micrographs of Modification of quartz with
iron oxide black via shaking.
[0015] FIG. 5 shows an SEM micrograph of Portland cement.
[0016] FIG. 6 shows an SEM micrograph of Portland cement modified
with iron oxide black via shaking.
[0017] FIG. 7 shows an SEM micrograph of alumina.
[0018] FIG. 8 shows an SEM micrograph of alumina modified with
carbon black.
[0019] FIG. 9 shows an SEM micrograph of silicon carbide.
[0020] FIG. 10 shows an SEM micrograph of silicon carbide modified
with carbon black.
[0021] FIG. 11 shows SEM micrographs of ATH filler dry-blended with
pigment and calcined ATH.
[0022] FIG. 12 is a plot of viscosity vs. spindle speed comparing
direct pigment addition to dry-blended addition of pigment.
[0023] FIG. 13 shows the particle size distribution plot of ATH
modified with carbon black made using a horizontal plough
mixer.
[0024] FIG. 14 shows the particle size distribution plot of ATH
(Alcan WH-311).
[0025] FIG. 15 shows the particle size distribution plot of a 1:1
(by weight) mixture of carbon black and ATH that was gently
combined.
[0026] FIG. 16 shows the particle size distribution plot of ATH
modified with carbon black made using a vertical high intensity
mixer.
[0027] FIG. 17 shows the particle size distribution plot of a
carbon black modified ATH made using an EIRICH mixer.
[0028] FIG. 18 shows an SEM micrograph of ATH simultaneously
modified with carbon black, iron oxide red, and iron oxide yellow
via shaking.
[0029] FIG. 19 shows an SEM micrograph of ATH modified with
Graphtol Fire Red pigment.
[0030] FIG. 20 shows an SEM micrograph of ATH modified with
titanium dioxide.
[0031] FIG. 21 shows an SEM micrograph of ATH modified with 0.2-0.3
micron fumed silica.
[0032] FIG. 22 shows an SEM micrograph of ATH modified with 0.007
micron fumed silica.
[0033] FIG. 23 illustrates scratches on various filled polymer
materials and histograms of scans of the scratches.
[0034] FIG. 24 is a plot of gray values of scratch scans.
[0035] FIG. 25 are photos of Test Plaques before and after hot
block testing.
[0036] FIG. 26 (prior art) illustrates scratches on various
comparative filled polymer materials and histograms of scans of the
scratches.
[0037] FIG. 27 (prior art) is a plot of gray values for scratches
on various comparative filled polymer materials.
DEFINITIONS
[0038] As employed herein, the term "solid surface material" is
employed in its normal meaning and represents a three dimensional
material such as a material particularly useful in the building
trades for kitchen countertops, sinks and wall coverings wherein
both functionality and an attractive appearance are necessary. In
general, solid surface materials are composite materials comprised
of a polymeric matrix and mineral filler.
[0039] As employed herein, the term "dye" means a colorant that, in
general, is soluble in the medium in which it is used, and
therefore not of a particulate nature but rather a multiplicity of
solvated molecules.
[0040] As employed herein, the term "pigment" means a colorant that
is insoluble in the medium in which it is used, and therefore of a
particulate nature encompassing the physical and chemical
properties thereof (e.g. surface charge, surface chemistry, and
topology).
[0041] As employed herein, the term "filler" means any material
that is solid at room temperature and atmospheric pressure, used
alone or in combination, and which is insoluble in the various
ingredients of the composition, even when these ingredients are
raised to a temperature above room temperature and in particular to
their softening point or their melting point.
[0042] As employed herein, the term "calcined ATH" means, alumina
trihydrate (ATH) which has been prepared by a thermal treatment
process to remove water from its surface.
[0043] As employed herein, the term "discrete functional particle"
means a material that is 1) not soluble in the medium in which it
is used and therefore in that medium does not exist as a
multiplicity of individual solvated molecules and 2) one that can
modify another solid material.
[0044] As described herein, the term "modified" means having
associated one or more discrete functional particles.
[0045] As employed herein, the term "associated" means held in
close proximity to a surface via an interaction including both
non-bonding interactions, such as van der waals forces, ion-dipole
interactions, dipole-dipole interactions, capillarity, and
electrostatic interactions, and also bonding interactions, such as
covalent bonding, ionic bonding, hydrogen bonding, metallic
bonding, acid-base interactions, Pearson-type acid-base
interactions, and dative (coordinate covalent) bonding.
DETAILED DESCRIPTION OF THE INVENTION
[0046] A first embodiment of the invention provides a filler
particle modified with discrete functional particles for
incorporation into filled polymer materials. The filler particle is
modified with discrete functional particles by dry-blending
discrete functional particles and filler in a high energy mixing
process prior to incorporating the resulting modified filler into a
liquid prepolymer mix. It is found that the dry-blending of
discrete functional particles with filler prior to incorporation
into a liquid prepolymerized mixture provides for a modified filler
particle with improved processing and performance characteristics.
The energy imparted by the blending process must be of sufficient
energy to bound, adhere, or otherwise associate the functional
particles to the filler.
[0047] Another embodiment of the invention provides a filler
particle modified with pigment particles for incorporation into
filled polymer materials. The filler particle is modified with
pigment by dry-blending discrete pigment particles and the filler
by employing a high energy mixing process prior to incorporating
the resulting modified filler into a liquid prepolymer mix. The
energy imparted by the dry-blending process must be of sufficient
energy to bound, adhere, or otherwise associate the pigment
particles to the filler. It is found that the dry-blending of
pigment particles with filler prior to incorporation into a liquid
prepolymerized mixture provides for a pigmented filler particle
with improved processing and performance characteristics when
compared to dyeing the filler, or by incorporating a liquid pigment
dispersion to a prepolymerized mix. It is also found that objects
made with filled polymer materials employing the dry-blended
pigment-modified filler have improved resistance to whitening due
to physical damage. It is also found that the dry-blending of
pigment with filler prior to incorporation into a liquid
prepolymerized mixture provides improved dispersion of colorants in
colored filled polymer materials wherein the modified filler will
withstand processing forces better than dyed filler or liquid
pigment dispersions. It is also found that dry-blending modified
filler particles provides a means for introducing a high loading of
pigment, to a level that direct addition of pigment does not
permit. High pigment loading via dry-blended filler is found to be
economical and convenient, whereas it is found that adding a high
level of pigment via a traditional dispersion is costly and
impractical given the relatively low concentration of pigment that
can be dispersed by those skilled in the art.
[0048] Another embodiment of the invention provides filled
polymeric materials comprising polymer at least partially filled
with filler particles that are modified with functional particles
by blending them in a dry-blending process wherein the collisions
are of sufficient energy to bound, adhere, or otherwise associate
the functional particles to the filler. The dry-blending process is
done prior to incorporating the resulting modified filler into a
liquid prepolymer mix. Various functional properties are
incorporated into the filled polymer material dependent on the
material used to modify the filler. It is found that dry-blending
discrete particles and a filler in a high energy mixing process
prior to incorporation into liquid prepolymer mixture provides a
filler particle that more strongly bonds with the discrete
functional particles than will be the case for dyed filler or
filler that is mixed with discrete functional particles in a low
energy mixing process.
[0049] The modified filler particle includes particulate filler. In
general, this filler increases the hardness, stiffness or strength
of the final article relative to the pure polymer or combination of
pure polymers. The filler is insoluble in the various ingredients
of typical liquid prepolymers. Some representative fillers include
alumina, alumina trihydrate (ATH), alumina monohydrate, aluminum
hydroxide, aluminum oxide, aluminum sulfate, aluminum phosphate,
aluminum silicate, Bayer hydrate, borosilicates, calcium sulfate,
calcium silicate, calcium phosphate, calcium carbonate, calcium
hydroxide, calcium oxide, apatite, quartz, quartzite, silica
(SiO.sub.2, including sand), glass bubbles, glass microspheres,
glass fibers, glass beads, glass flakes, glass powder, glass
spheres, carbon fibers, ceramic fibers, metal fibers, polymer
fibers, nano-wood fibers, carbon nanotubes, graphene, clay, barium
carbonate, barium hydroxide, barium oxide, barium sulfate, barium
phosphate, barium silicate, magnesium sulfate, magnesium silicate,
magnesium phosphate, magnesium hydroxide, magnesium oxide, kaolin,
montmorillonite, bentonite, pyrophyllite, mica, gypsum, ceramic
microspheres and ceramic particles, powder talc, titanium dioxide,
diatomaceous earth, wood flour, borax, silicon carbide, Portland
cement, or combinations thereof. The filler is present in the form
of small particles, with an average particle size in the range of
from about 0.1-500 microns. The preferred filler is a mineral
particle. A particularly preferred filler is alumina trihydrate.
Another particularly preferred filler is quartz.
[0050] The modified filler particle includes discrete functional
particles. The functional particles may be any natural or
synthetic, organic or inorganic matter, usually in the form of an
insoluble powder. Functional particles may be any combination of
functional particles.
[0051] A preferred discrete functional particle is pigment. When
the filler is modified with pigment and the subsequent modified
filler particle is incorporated into a polymeric material, it is
found to impart improved colorant characteristics. When modifying
the filler with pigment, the preferred pigments are iron oxides and
carbon black.
[0052] Other useful discrete functional particles are energy
absorption modifiers. Energy absorption modifiers include UV
absorption modifiers, UV stabilization modifiers, IR absorption
modifiers, radiofrequency wave absorption modifiers, fluorescent
response modifiers, phosphorescent response modifiers,
thermochromism modifiers, electrical conductivity modifiers,
magnetic characteristic modifiers, or any combination thereof.
[0053] Other useful discrete functional particles are mechanical
property modifiers. Mechanical property modifiers include surface
hardness modifiers, lubricity modifiers, strength modifiers,
toughness modifiers, impact resistance modifiers, scratch
resistance modifiers, mar resistance modifiers, and any combination
thereof.
[0054] Other useful discrete functional particles are materials
that modify the surface properties of the filler particles. Surface
property modifiers include stain resistance modifiers, lubricity
modifiers, adhesion modifiers, absorbability modifiers, flame
retardants, antimicrobial agents, modifiers of self-cleanability,
modifiers of self-healing of a polymeric matrix comprising the
modified filler particle, acidity or alkalinity modifiers,
modifiers of electrical characteristics, modifiers of magnetic
properties, or any combination thereof.
[0055] Other useful discrete functional particles are materials
that modify the interaction of the filler particles with a
surrounding medium when the modified filler particle is added to
the medium. Useful materials include surface tension modifiers,
rheology modifiers, modifiers of the agglomeration state of the
modified filler particle, modifiers of the packing efficiency of
the modified filler particle, compatibilizers, dispersants, or any
combination thereof.
[0056] In the present invention, particles are present in two
different size distributions. It is considered that the benefits of
modifying the filler particle with functional particles do not
occur to the desired degree if the particle size distribution is
not present. A particle size distribution for the filler is in a
range from 0.1 micron to 100 microns, more preferably 7 to 100, and
most preferably 10 to 50 microns.
[0057] A particle size distribution for the functional particles is
from 0.005 microns to 4 microns, more preferably from 0.01 to 3
microns. It is believed that most commercial pigments are in the
0.2 to 3 micron range.
[0058] The ratio of the filler to the functional particles may
range on a weight basis from 99.9:0.1 up to 10:90.
[0059] The dry-blending process employs a high energy mixing
process. A high energy mixing process mixes the functional
particles and filler to a homogeneous mixture in 60 minutes or
less. Without being bound to theory, it is believed that a high
energy mixing process creates a bond between pigment and filler
that is stronger than low energy mixing processes. A suitable high
shear mixing process is an air driven pitch-blade turbine with a
high shaft speed. A suitable shaking process employs a paint shaker
run at a high speed. Optional mixing processes include microwave
blending, shaking, tumbling, milling (jet, ball), supercritical
fluids, homogenizer, electrostatic fields, magnetic fields,
horizontal plough mixer, vertical high intensity mixer, horizontal
or vertical blade mixer, EIRICH-type mixer, pin mill, hammer mill,
fluidized bed, vibratory, sonication, blenders (V-shaped, double
cone), or a combination thereof.
[0060] The preferred use of the dry-blended modified filler of the
present invention is in a solid surface material. Solid surface
materials are filled polymeric materials and various methods for
their manufacture are known in the art. The preferred solid surface
material is an acrylic containing composition. The preparation of a
polymerizable acrylic composition consisting essentially of a sirup
containing methyl methacrylate polymer dissolved in monomeric
methyl methacrylate (polymer-in-monomer syrup), a polymerization
initiator, and inorganic filler, preferably alumina trihydrate, is
disclosed in U.S. Pat. No. 3,847,865 issued to Ray B. Duggins. The
composition can be cast or molded and cured to produce a sheet
structure with an important combination of properties including
translucency, weather resistance, resistance to staining by common
household materials, flame resistance, and resistance to stress
cracking. In addition, the cured article can be easily machined by
conventional techniques including sawing and sanding. This
particular combination of properties makes such a structure
particularly useful as kitchen or bathroom countertops, back splash
panels, molded articles such as towel racks, and the like. The
polymer constituent comprises 15 to 80%, preferably 20 to 45% by
weight of the filled article and may comprise methyl methacrylate
homopolymers and copolymers of methyl methacrylate with other
ethylenically unsaturated compounds (e.g., vinyl acetate, styrene,
alkyl acrylates, acrylonitrile, alkyl methacrylates,
multifunctional acrylic monomers such as alkylene dimethacrylates
and alkylene diacrylates). In addition, the polymer constituent can
contain small amounts of other polymers including minor amounts of
polyester. The solid surface material also contains 20 to 85%,
preferably about 55 to 80% of filler. The preferred filler is the
dry-blended filler of the present invention. Optional materials
generally used as fillers may be combined in the liquid prepolymer
mixture along with the dry-blended filler, for example, titanates,
barium sulfates, calcium carbonate, lithopone, china clays,
magnesite, mica, iron oxides, silicone dioxide, and various
siennas. Optionally, the solid surface material may contain
macroscopic decorative particles known to the industry as
"crunchies". Crunchies are various filled and unfilled, pigmented
or dyed, insoluble or crosslinked chips of polymers such as ABS
resins, cellulose esters, cellulose ethers, epoxy resins,
polyethylene, ethylene copolymers, melamine resins, phenolic
resins, polyacetals, polyacrylics, polydienes, polyesters,
polyisobutylenes, polypropylenes, polystyrenes, urea/formaldehyde
resins, polyureas, polyurethanes, polyvinyl chloride,
polyvinylidene chloride, polyvinyl esters and the like. Other
useful macroscopic translucent and transparent decorative particles
are natural or synthetic minerals or materials such as agate,
alabaster, albite, calcite, chalcedony, chert, feldspar, flint
quartz, glass, malachite, marble, mica, obsidian, opal, quartz,
quartzite, rock gypsum, sand, silica, travertine, wollastonite and
the like; cloth, natural and synthetic fibers; and pieces of metal.
When incorporating the dry-blended modified filler into liquid
prepolymer mixtures, various filler materials modified with various
pigment materials may be combined. Optional uses of the dry-blended
filler include cable coating, carpet backing, and concrete.
[0061] The dry-blended modified filler may be combined with
polymeric matrices using processes other than liquid prepolymer,
such as casting, melt processing, powder coating, solution
processing, slip casting, tape casting, vibrocompaction,
compression molding, sintering, extrusion, and injection
molding.
[0062] The following examples are included as representative of the
embodiments of the present invention.
EXAMPLES
Example 1
Modification of ATH with Pigment Particles Via Shearing
[0063] In eight separate preparations, a 1-quart vessel was charged
with 217.5 g of alumina trihydrate (Alcan WH-311). While stirring
at 500 RPM with a four-blade air driven pitch-blade turbine, 32.5 g
of a given solid pigment was added over the course of 15 minutes.
Mixing was continued until the mixture appeared to be homogenously
colored. SEM micrographs were acquired for each sample of modified
filler:
TABLE-US-00001 Figure of SEM Pigment Micrograph NONE; unmodified
ATH 1A BASF Magnetic Black S 0045 1B Iron Oxide Yellow 1888D 1C
Kroma Red 3097 1D Irgazin Blue 3367 1E Monolite Green 751 1F Meteor
Bright Yellow 8320 1G Quinacridone Red Violet 19 1H Arosperse F138
Carbon Black 1I
[0064] The micrographs demonstrate that a shearing process is
effective in modifying a filler with a pigment, and that the
dry-blending process works on organic, inorganic and carbon black
pigments.
[0065] Each of the eight samples of the dry-blended
pigment-modified fillers was then subjected to washing in methyl
methacrylate to ensure persistence of the pigment modification in a
manufacturing process. Specifically, the test is designed to
determine if the pigment would disassociate from the filler and
cause color blotches in objects made from liquid prepolymers
incorporating the modified filler. In each case, 10.0 g of the
modified filler was placed in a 40-mL glass vial. To this was added
30.0 g of methyl methacrylate. The vials were capped and placed on
a wrist-action shaker table for four hours. The fully-suspended
mixtures were cast into shallow aluminum pans. The bulk methyl
methacrylate was allowed to evaporate. Following this, the samples
were placed in a drying oven at 45.degree. C. for one hour. The
temperature of the oven was increased .about.10.degree. C. every
hour for four hours. The total drying time was 6 hours. Visual
inspection confirmed that for all eight samples the pigment
remained on the filler. The micrographs show that the pigment
persisted with an association that is strong enough to withstand
subsequent processing, in particular suspension and mixing in a
polar liquid medium. SEM micrographs were acquired for three of the
dried samples:
TABLE-US-00002 Figure Reference Initial Washed, Cast, Sample Sample
and Dried Sample ATH Modified with Iron Oxide Yellow 2A 2B 1888D
ATH Modified with Arosperse F138 Carbon 2C 2D Black ATH Modified
with Quinacridone Red 2E 2F Violet 19
Example 2
Modification of ATH with Iron Oxide Black Via Shaking
[0066] A one-gallon paint can was charged with 1,500 g ATH and
714.3 g Bayferrox 318NM (iron oxide black). The vessel was sealed
and then shaken on a Red Devil single-arm paint shaker for 30
minutes at which point the components appeared to be homogeneously
blended. The sample was analyzed by SEM (FIG. 3C). The micrograph
shows the presence of relatively small iron oxide black particles
on the surface of the relatively large ATH particles. This
demonstrates that a shaking process is effective in modifying a
filler with a functional particle.
Example 3
Modification of Quartz with Iron Oxide Black Via Shaking
[0067] A one-gallon paint can was charged with 217.5 g of Blackburn
84 mesh quartz and 32.5 g of Bayferrox 318NM (iron oxide black).
The vessel was sealed and then shaken on a Red Devil single-arm
paint shaker for 30 minutes at which point the components appeared
to be homogeneously blended. The sample was analyzed by SEM (FIG.
4B) along with an unmodified sample of quartz (FIG. 4A) The
micrographs show the presence of relatively small iron oxide black
particles evenly distributed on the surface of the large quartz
particles, indicating a homogeneous blend.
[0068] The modified sample was subjected to the methyl methacrylate
washing procedure of Example 1. An SEM micrograph of the washed,
cast, and dried sample was acquired (FIG. 4C). The micrograph shows
that the pigment modification persisted with an association that is
strong enough to withstand subsequent processing, in particular
suspension and mixing in a polar liquid medium.
Example 4
Modification of Portland Cement with Iron Oxide Black Via
Shaking
[0069] A one-gallon paint can was charged with 1,224 g Portland
cement (Quikrete) and 576 g iron oxide black (Bayferrox 318). The
vessel was sealed and then shaken on a Red Devil single-arm paint
shaker for 60 minutes. The sample was a fine free-flowing uniformly
dark black powder. Analysis by SEM revealed the presence of small
iron oxide particles on the surface of the cement (see FIG. 5
(unmodified cement) versus FIG. 6 (cement modified with iron oxide
black)).
[0070] This demonstrates that a mixture of inorganic compounds,
such as Portland cement, can be modified by functional particles
using the processes described here.
Example 5
Modification of Alumina with Carbon Black Via Shaking
[0071] A one-gallon paint can was charged with 1,757.5 g alumina
(C-1, 87 micron, Rio Tinto Alcan) and 42.5 g Arosperse F138 carbon
black. The vessel was sealed and then shaken on a Red Devil
single-arm paint shaker for 60 minutes. The sample was a fine
free-flowing uniformly dark black powder. Analysis by SEM revealed
the presence of small carbon black particles on the surface of the
alumina (see FIG. 7 (unmodified alumina) versus FIG. 8 (alumina
modified with carbon black)).
[0072] This further demonstrates that a metal oxide filler can be
modified by functional particles using the processes described
here.
Example 6
Modification of Silicon Carbide with Carbon Black Via Shaking
[0073] A one-gallon paint can was charged with 1,757.5 g silicon
carbide (Black Silicon Carbide Grain, 80 micron, Silicon Carbide
Products) and 42.5 g Arosperse F138 carbon black. The vessel was
sealed and then shaken on a Red Devil single-arm paint shaker for
60 minutes. The sample was a fine free-flowing uniformly dark black
powder. Analysis by SEM revealed the presence of small particles on
the surface of the silicon carbide (see FIG. 9 (unmodified silicon
carbide) versus FIG. 10 (silicon carbide modified with carbon
black)).
[0074] This demonstrates that a carbide compound can be modified by
functional particles using the processes described here.
Example 7
Modification of ATH with Carbon Black Via Shaking, and Subsequent
Processing
[0075] A one-gallon paint can was charged with 1,500 g ATH and 36.3
g Arosperse F138 (carbon black). The vessel was sealed and then
shaken on a Red Devil single-arm paint shaker for 30 minutes to
create a dry-blended modified filler. A sample of the modified
filler was analyzed by SEM (FIG. 11C). The micrograph shows the
presence of relatively small carbon black particles evenly
distributed on the surface of the relatively large ATH
particles.
[0076] A first test sample was prepared by combining a first 125 g
sample of the above mixture with 125 g of unmodified ATH in a one
quart vessel and dry-blending them in a Red Devil single-arm paint
shaker for 30 minutes to create dry-blended modified filler. A
second sample was prepared by combing a second 125 g sample of the
above mixture combined with 125 g of calcined ATH in a one quart
vessel and dry-blending them in a Red Devil single-arm paint shaker
for 30 minutes to create dry-blended modified filler. The calcined
ATH had been prepared by heating ATH to 800.degree. C. for 24 hours
to remove all three water molecules of hydration. Both samples were
analyzed by SEM. The micrograph of the first sample comprised of
carbon black-modified ATH dry-blended with an equal weight of
unmodified ATH (FIG. 11D) shows an even coating of carbon black
particles on all ATH particles, similar to what is shown in FIG.
11C. However, the micrograph of the second sample comprised of
carbon black-modified ATH dry-blended with an equal weight of
calcined ATH (FIG. 11E) shows a mixture of particles with different
surface morphologies, some exhibiting rigidly geometric and sharp
edges (FIG. 11F), others exhibiting relatively smooth edges (FIG.
11G). The former are unmodified particles of calcined ATH, the
latter being intact modified particles of ATH. This shows that
carbon black particles present on the surface of dry-blended ATH
can redistribute among unmodified ATH particles when subjected to
dry-blending. However, when carbon black-tinted ATH particles are
combined with calcined ATH and dry-blended, the carbon black
particles remain on the surface of the dry-blended pigment-modified
ATH and do not redistribute among the calcined ATH. Thus, the
forces involved in typical polymer processing are of insufficient
energy to redistribute pigment among fillers with vastly different
surface chemistries. The pigment will remain with the filler to
which it is modified during dry-blending. This demonstrates that
the dry-blended pigment-modified filler will withstand processing
forces.
Example 8
Modification of ATH with Quinacridone Red Violet Via Shaking and
Formation of a Filled Acrylic Composite Using the Modified
Filler
[0077] A one-gallon paint can was charged with 1,500 g of ATH
(Alcan WH-311) and 24.20 g of quinacridone red violet 19 (Lansco
Colors). The vessel was sealed and then shaken on a Red Devil
single-arm paint shaker for 30 minutes to create a first batch.
This procedure was repeated a second time to create a second batch.
The first batch and the second batch were combined to form a test
batch of dry-blended filler.
[0078] An experimental Test Plaque (Test Plaque 8A) was prepared
from a liquid prepolymer mixture consisting of 87.0 g methyl
methacrylate (MMA), 260.9 g of a 24 wt. % acrylic polymer solution
(polymethyl methacrylate of molecular weight approximately 30
kg/mol dissolved in MMA), 4.3 g trimethylolpropane trimethacrylate,
10.0 g tert-butylperoxymaleic acid (PMA-25, Arkema), 0.7 g of Zelec
PH unsaturated phosphoric acid ester (Stepan Co.) and 1.5 g
AOT-S(Cytec) was blended at room temperature. While stirring at 300
rpm with an air-driven pitch blade turbine, 630.0 g of the
dry-blended quinacridone red modified ATH filler described above
was added over one minute. Mixing was continued for two additional
minutes. The resultant mixture was transferred to an enclosed
vessel where dissolved gases were removed in vacuo (24 inHg) over a
period of two minutes while stirring at 1,000 rpm. While still
under vacuum, 4.2 g of a calcium hydroxide suspension (45 wt. % in
solvent) was added via syringe through a rubber septum. This was
immediately followed by addition of 1.6 g ethylene glycol
dimercaptoacetate (GDMA). After mixing for 30 seconds, the vacuum
was released and the mixture was poured into a film-lined casting
cavity which was pre-heated to 35.degree. C. Film was placed on the
backside of the casting, and an insulated cover was placed on top.
The mixture cured within 15 minutes. After allowing the resultant
plaque to cool to room temperature, it was rough-finished in a drum
sander and then sanded with progressively finer grit sand paper
ending with 4000-grit to create Test Plaque 8A.
[0079] A control Test Plaque (Test Plaque 8B) of a liquid
dispersion pigmented filled polymeric material was prepared from a
liquid prepolymer mixture prepared in the same manner as above.
While stirring at 300 rpm with an air-driven pitch blade turbine,
620.0 g of unmodified ATH (Alcan WH-311) was added over one minute.
Mixing was continued for two additional minutes. Afterwards, 10.0 g
of quinacridone red violet 19 (Lansco Color) was added to the
stirring mixture over one minute. Mixing was again continued for
two additional minutes. The resultant mixture was transferred to an
enclosed vessel where dissolved gases were removed in vacuo (24
inHg) over a period of two minutes while stirring at 1,000 rpm.
While still under vacuum, 4.2 g of a calcium hydroxide suspension
(45 wt. % in solvent) was added via syringe through a rubber
septum. This was immediately followed by addition of 1.6 g ethylene
glycol dimercaptoacetate (GDMA). After mixing for 30 seconds, the
vacuum was released and the mixture was poured into a film-lined
casting cavity which was pre-heated to 35.degree. C. Film was
placed on the backside of the casting, and an insulated cover was
placed on top. The mixture cured within 15 minutes. After allowing
the resultant plaque to cool to room temperature, it was
rough-finished in a drum sander and then sanded with progressively
finer grit sand paper ending with 4000-grit to create Test Plaque
8B.
[0080] A Hunter Miniscan spectrophotometer was used to measure the
color of both Test Plaques. The L, a, b color space is used to
describe the color measurement where the `L` value is a measure of
lightness (low `L` is dark, high `L` is light), the `a` value
represents the red/green axis (negative `a` is toward a green hue,
positive `a` is toward a red hue) and the `b` value represents the
yellow/blue axis (negative `b` is toward a blue hue, positive `b`
is toward a yellow hue). The difference in color between two
samples (or a single sample before and after a physical test) can
be represented as the change in each color axis: .DELTA.L,
.DELTA.a, and .DELTA.b. Alternatively, the root-mean-square average
of the three delta-values can be calculated to give a total color
difference, .DELTA.E. As shown in Table 1, there is a significant
difference in the color of the composites, despite an equal loading
of pigment. In particular, the L value for the composite of Test
Plaque 8B is two units higher (lighter) than that of Test Plaque
8A. This represents a difference in tinting strength of the
pigment, indicating a poor dispersion of pigment particles in
5B.
TABLE-US-00003 TABLE 1 L a b color values L a b Test Plaque 8A
(dry-blended) 31.15 28.02 8.23 Test Plaque 8B (liquid dispersion)
33.22 31.25 8.92
Example 9
Modification of ATH with Carbon Black Via Shaking and Formation of
a Filled Acrylic Composite Using the Modified Filler
[0081] A one-gallon paint can was charged with 1,500 g ATH (Alcan
WH-311) and 36.3 g Arosperse F138 carbon black (Evonik). The vessel
was sealed and then shaken on a Red Devil single-arm paint shaker
for 30 minutes to create a first batch of modified filler. This
procedure was repeated a second time, the resulting batch of
modified filler being combined with the first batch to create a
total batch of dry-blended filler.
[0082] An experimental Test Plaque (Test Plaque 9A) was prepared
from a liquid prepolymer mixture consisting of 85.8 g methyl
methacrylate (MMA), 257.3 g of a 24 wt. % acrylic polymer solution
(polymethyl methacrylate of molecular weight approximately 30
kg/mol dissolved in MMA), 4.2 g trimethylolpropane trimethacrylate,
9.9 g tert-butylperoxymaleic acid (PMA-25, Arkema), 0.7 g of Zelec
PH unsaturated phosphoric acid ester (Stepan Co.) and 1.5 g
AOT-S(Cytec) was blended at room temperature. While stirring at 300
rpm with an air-driven pitch blade turbine, 635.0 g of the carbon
black modified ATH described above was added over one minute.
Mixing was continued for two additional minutes. Brookfield
viscosity of the mixture was measured at this point (RV-DV-II, S-72
vane spindle, 21-22.degree. C.) and is shown in FIG. 12. The
mixture was then transferred to an enclosed vessel where dissolved
gases were removed in vacuo (24 inHg) over a period of two minutes
while stirring at 1,000 rpm. While still under vacuum, 4.1 g of a
calcium hydroxide suspension (45 wt. % in solvent) was added via
syringe through a rubber septum. This was immediately followed by
addition of 1.6 g ethylene glycol dimercaptoacetate (GDMA). After
mixing for 30 seconds, the vacuum was released and the mixture was
poured into a film-lined casting cavity which was pre-heated to
35.degree. C. Film was placed on the backside of the casting, and
an insulated cover was placed on top. The mixture cured within 15
minutes. After allowing the resultant plaque to cool to room
temperature, it was rough-finished in a drum sander and then sanded
with progressively finer grit sand paper ending with 240-grit to
create Test Plaque 9A, a filled polymeric material pigmented with
dry-blended filler.
[0083] A control Test Plaque (Test Plaque 9B) was prepared from a
liquid prepolymer mixture prepared in the same manner as above.
While stirring at 300 rpm with an air-driven pitch blade turbine,
620.0 g of unmodified ATH (Alcan WH-311) was added over one minute.
Mixing was continued for two additional minutes. Afterwards, 15.0 g
of Arosperse F138 was added to the stirring mixture over one
minute. Mixing was again continued for two additional minutes.
Brookfield viscosity of the mixture was measured at this point
(RV-DV-II, S-72 vane spindle, 21-22.degree. C.) and is shown in
FIG. 12. The mixture was then transferred to an enclosed vessel
where dissolved gases were removed in vacuo (24 inHg) over a period
of two minutes while stirring at 1,000 rpm. While still under
vacuum, 4.1 g of a calcium hydroxide suspension (45 wt. % in
solvent) was added via syringe through a rubber septum. This was
immediately followed by addition of 1.6 g ethylene glycol
dimercaptoacetate (GDMA). After mixing for 30 seconds, the vacuum
was released and the mixture was poured into a film-lined casting
cavity which was pre-heated to 35.degree. C. Film was placed on the
backside of the casting, and an insulated cover was placed on top.
The mixture cured within 15 minutes. After allowing the resultant
plaque to cool to room temperature, it was rough-finished in a drum
sander and then sanded with progressively finer grit sand paper
ending with 240-grit to create Test Plaque 9B, a filled polymeric
material with pigment added directly to the liquid prepolymer
mixture.
[0084] A plot of the viscosity of the liquid prepolymer mixture vs.
the spindle speed of the air-driven pitch blade turbine is given in
FIG. 12 for both of the Test Plaques. The mixture of Test Plaque 9B
(where carbon black was added directly to the batch) exhibits a
higher viscosity at all spindle speeds and, further, exhibits
significant shear thinning behavior than that of Test Plaque
9A.
[0085] Test Plaque 9A was of high visual quality, exhibiting a
uniform black appearance. Test Plaque 9B was of poor visual
quality, exhibiting dark spots visible on all surfaces of the
plaque. The dark spots were determined to be agglomerated pigment
under visual inspection.
[0086] A Hunter Miniscan spectrophotometer was used to measure the
color of both Test Plaques. As shown in Table 2, there is a
significant difference in L color of the composites, despite an
equal loading of pigment. The L value of Test Plaque 9B is 1.13
units lighter than that of Test Plaque 9A, again indicating that
adding the pigment directly to the ATH-containing mixture results
in poor dispersion of the pigment and, thus, low tinting
strength.
TABLE-US-00004 TABLE 2 L a b Color Values L a b Composite of Test
Plaque 9A 24.90 -0.25 -1.63 Composite of Test Plaque 9B 26.03 -0.37
-2.00
[0087] This demonstrates that dry-blending provides a means for
introducing a functional particle (such as a pigment) into a liquid
prepolymer mixture in a manner that achieves enhanced color
characteristics when compared to traditional direct addition to the
liquid prepolymer mixture.
[0088] It also demonstrates that the addition of pigment directly
into the liquid prepolymer results in agglomerate formation and a
reduction in the tinting strength of the pigment as compared to the
addition of pigment to a filled prepolymer mixture by first bonding
the pigment to filler by dry-blending them before combining with
the liquid prepolymer.
[0089] It also demonstrates that the addition of pigment to a
filled prepolymer mixture by first bonding the pigment to filler by
dry-blending them before combining with the liquid prepolymer
results in a significant decrease in the viscosity of the mixture.
Decreased viscosity of the prepolymer is beneficial to
manufacturing processes that are required in order to form objects
from the prepolymer.
Example 10
Modification of ATH with Carbon Black Using a Commercial Scale
Horizontal Plough Mixer with Chopper and Formation of a Filled
Acrylic Composite Using the Modified Filler
[0090] A 130-L Littleford Day horizontal plough mixer (model
FM-130), equipped with an 4-blade inverted Christmas tree chopper
(4 inch, 6 inch, 7 inch, 7 inch) was charged with 172.5 lbs of ATH
(Alcan WH-311) and 4.13 lbs of Arosperse F-138 carbon black
(Evonik). The mixer was run with a plough speed of 155 rpm and a
chopper speed of 3,400 rpm. A sample of the mixture was taken after
5 minutes. The sample was a fine free-flowing uniformly dark
powder. Analysis by SEM revealed the presence of carbon black on
the surface of the ATH, comparable to what is depicted for
materials generated using small scale methods, such as shaking.
[0091] The sample was subjected to particle size analysis via light
scattering using a Malvern Mastersizer 2000. The sample was
measured in water with sodium metaphosphate as dispersant. The
particle size distribution (PSD) is shown in FIG. 13. It nearly
overlays the PSD of the unmodified ATH which is depicted in FIG.
14. In contrast, a sample made by combining ATH and carbon black
(1:1 by weight) and then gently and manually mixing yields a sample
with a bimodal and broad PSD (FIG. 15). As expected, a functional
particle-modified filler made by the processes described here gives
a single unimodal PSD curve while a simple mixture of the same two
components gives a broad, bimodal PSD curve.
[0092] The sample was used to cast an experimental Test Plaque
(Test Plaque 10-A). This was prepared from a liquid prepolymer
mixture consisting of 83.4 g methyl methacrylate (MMA), 264.00 g of
a 24 wt. % acrylic polymer solution (polymethyl methacrylate of
molecular weight approximately 30 kg/mol dissolved in MMA), 4.26 g
trimethylolpropane trimethacrylate, 7.10 g tert-butylperoxymaleic
acid (PMA-25, Arkema), 0.68 g of Zelec PH unsaturated phosphoric
acid ester (Stepan Co.) and 1.50 g AOT-S(Cytec) which were blended
at room temperature. While stirring at 300 rpm with an air-driven
pitch blade turbine, 635.0 g of the carbon black modified ATH
described above was added over one minute. Mixing was continued for
two additional minutes. The mixture was then transferred to an
enclosed vessel where dissolved gases were removed in vacuo (24
inHg) over a period of two minutes while stirring at 1,000 rpm.
While still under vacuum, 2.98 g of a calcium hydroxide suspension
(45 wt. % in solvent) was added via syringe through a rubber
septum. This was immediately followed by addition of 1.11 g
ethylene glycol dimercaptoacetate (GDMA). After mixing for 30
seconds, the vacuum was released and the mixture was poured into a
film-lined casting cavity which was pre-heated to 35.degree. C.
Film was placed on the backside of the casting, and an insulated
cover was placed on top. The mixture cured within 15 minutes. After
allowing the resultant plaque to cool to room temperature, it was
rough-finished in a drum sander and then sanded with progressively
finer grit sand paper ending with 500-grit to create Test Plaque
10-A, a filled polymeric material pigmented with dry-blended
filler. The Test Plaque was of high quality, exhibiting uniform
coloration and no visual defects.
[0093] This demonstrates that a horizontal plough mixer is an
effective machine to modify a filler with a functional
particle.
Example 11
Modification of ATH with Carbon Black Using a Commercial Scale
Vertical High Intensity Mixer
[0094] A 180-L Littleford Day vertical high intensity mixer (Model
W-180) was charged with 200 lbs of ATH (Alcan WH-311) and 4.92 lbs
of Arosperse F-138 carbon black (Evonik). The mixer was run with a
plough speed of 900 rpm. A sample of the mixture was taken after 5
minutes. The sample was a fine free-flowing uniformly dark
powder.
[0095] The sample was subjected to particle size analysis using the
same technique as described in Example 10. The PSD is depicted in
FIG. 16. The curve is relatively narrow and unimodal indicating
that a single particulate material was generated through
modification of the filler (ATH) with a functional particle (carbon
black).
[0096] The sample was used to cast an experimental Test Plaque
(Test Plaque 11-A). The same formulation, casting procedure, and
plaque finishing procedure described in Example 10 were used. The
Test Plaque was of high quality, exhibiting uniform coloration and
no visual defects.
[0097] This demonstrates that a vertical high intensity mixer is an
effective machine to modify a filler with a functional
particle.
Example 12
Modification of ATH with Carbon Black Using an EIRICH Mixer
[0098] An EIRICH mixer (RVO2E) equipped with a star-type rotor was
charged with 52.7 kg of ATH (Alcan WH-311) and 1.3 kg of Arosperse
F-138 carbon black (Evonik). The mixer was run with an agitator tip
speed of 30 m/s and a pan rotation speed of 37 rpm. A sample of the
mixture was taken after 5 minutes. The sample was a fine
free-flowing uniformly dark powder.
[0099] The sample was subjected to particle size analysis using the
same technique as described in Example 10. The PSD is depicted in
FIG. 17. The curve is relatively narrow and unimodal indicating
that a single particulate material was generated through
modification of the filler (ATH) with a functional particle (carbon
black).
[0100] The sample was used to cast an experimental Test Plaque
(Test Plaque 12-A). The same formulation, casting procedure, and
plaque finishing procedure described in Example 10 were used. The
Test Plaque was of high quality, exhibiting uniform coloration and
no visual defects.
[0101] This demonstrates that an EIRCH-type mixer is an effective
machine to modify a filler with a functional particle.
Example 13
Modification of ATH with Carbon Black, Iron Oxide Red, and Iron
Oxide Yellow Simultaneously Via Shaking and Formation of a Filled
Acrylic Composite Using the Modified Filler
[0102] A one-gallon paint can was charged with 1,758.42 g ATH
(Alcan WH-311) and 9.54 g Arosperse F138 carbon black (Evonik),
16.02 g iron oxide red (Rockwood, Kroma Red, R03097) and 16.02 g
iron oxide yellow (Rockwood, Ultra Yellow, YL01888D). The vessel
was sealed and then shaken on a Red Devil single-arm paint shaker
for 60 minutes. The sample was a fine free-flowing uniformly dark
brown powder. Analysis by SEM revealed the presence of a multitude
of particles on the surface of the ATH (see FIG. 1A (unmodified
ATH) versus FIG. 18 (ATH modified with carbon black, iron oxide
red, and iron oxide yellow)).
[0103] An experimental Test Plaque (Test Plaque 13-A) was prepared
from a liquid prepolymer mixture consisting of 83.4 g methyl
methacrylate (MMA), 264.00 g of a 24 wt. % acrylic polymer solution
(polymethyl methacrylate of molecular weight approximately 30
kg/mol dissolved in MMA), 4.26 g trimethylolpropane
trimethacrylate, 7.10 g tert-butylperoxymaleic acid (PMA-25,
Arkema), 0.68 g of Zelec PH unsaturated phosphoric acid ester
(Stepan Co.) and 1.50 g AOT-S(Cytec) which were blended at room
temperature. While stirring at 300 rpm with an air-driven pitch
blade turbine, 635.0 g of the modified ATH described above was
added over one minute. Mixing was continued for two additional
minutes. The mixture was then transferred to an enclosed vessel
where dissolved gases were removed in vacuo (24 inHg) over a period
of two minutes while stirring at 1,000 rpm. While still under
vacuum, 2.98 g of a calcium hydroxide suspension (45 wt. % in
solvent) was added via syringe through a rubber septum. This was
immediately followed by addition of 1.11 g ethylene glycol
dimercaptoacetate (GDMA). After mixing for 30 seconds, the vacuum
was released and the mixture was poured into a film-lined casting
cavity which was pre-heated to 35.degree. C. Film was placed on the
backside of the casting, and an insulated cover was placed on top.
The mixture cured within 15 minutes. After allowing the resultant
plaque to cool to room temperature, it was rough-finished in a drum
sander and then sanded with progressively finer grit sand paper
ending with 500-grit to create Test Plaque 13-A, a filled polymeric
material pigmented with dry-blended filler. The Test Plaque was of
high quality, exhibiting uniform coloration and no visual
defects.
[0104] This demonstrates that a filler can be modified with
multiple functional particles in one step using the processes
described herein.
Example 14
Modification of ATH with an Azo/Strontium Salt Pigment Via Shaking
and Formation of a Filled Acrylic Composite Using the Modified
Filler
[0105] A one-gallon paint can was charged with 1,746.00 g ATH
(Alcan WH-311) and 54.00 g Graphtol Fire Red 3RLP (Clariant). The
vessel was sealed and then shaken on a Red Devil single-arm paint
shaker for 60 minutes. The sample was a fine free-flowing uniformly
bright red/orange powder. Analysis by SEM revealed the presence of
small pigment particles on the surface of the ATH (see FIG. 1A
(unmodified ATH) versus FIG. 19 (ATH modified with Graphtol Fire
Red)).
[0106] The sample was used to cast an experimental Test Plaque
(Test Plaque 14-A). The same formulation, casting procedure, and
plaque finishing procedure as described in Example 13 were used,
except for a substitution with the modified ATH prepared in this
example. The Test Plaque was of high quality, exhibiting uniform
coloration and no visual defects.
[0107] This demonstrates that a filler can be modified with a
pigment described as a metal salt of an azo compound, using the
processes described herein.
Example 15
Modification of ATH with Titanium Dioxide Via Shaking and Formation
of a Filled Acrylic Composite Using the Modified Filler
[0108] A one-gallon paint can was charged with 1,746.00 g ATH
(Alcan WH-311) and 54.00 g Titanium Dioxide (TiPure R960, DuPont).
The vessel was sealed and then shaken on a Red Devil single-arm
paint shaker for 60 minutes. The sample was a fine free-flowing
uniformly white powder. Analysis by SEM revealed the presence of
small titanium dioxide particles on the surface of the ATH (see
FIG. 1A (unmodified ATH) versus FIG. 20 (ATH modified with titanium
dioxide)).
[0109] The sample was used to cast an experimental Test Plaque
(Test Plaque 15-A). The same formulation, casting procedure, and
plaque finishing procedure as described in Example 13 were used,
except for a substitution with the modified ATH prepared in this
example. The Test Plaque was of high quality, exhibiting uniform
coloration and no visual defects.
[0110] This demonstrates that a filler can be modified with
titanium dioxide using the processes described herein.
Example 16
Modification of ATH with Fumed Silica (0.2-0.3 Micron) Via Shaking
and Formation of a Filled Acrylic Composite Using the Modified
Filler
[0111] A one-gallon paint can was charged with 1,757.5 g ATH (Alcan
WH-311) and 42.5 g fumed silica, (0.2-0.3 microns, Aldrich). The
vessel was sealed and then shaken on a Red Devil single-arm paint
shaker for 60 minutes. The sample was a fine free-flowing uniformly
white powder. Analysis by SEM revealed the presence of small silica
particles on the surface of the ATH (see FIG. 1A (unmodified ATH)
versus FIG. 21 (ATH modified with 0.2-0.3 micron fumed
silica)).
[0112] The sample was used to cast an experimental Test Plaque
(Test Plaque 16-A). The same formulation, casting procedure, and
plaque finishing procedure as described in Example 13 were used,
except for a substitution with the modified ATH prepared in this
example. The Test Plaque was of high quality, exhibiting uniform
coloration and no visual defects.
[0113] This demonstrates that a filler can be modified with an
amorphous silica particle compound using the processes described
herein.
Example 17
Modification of ATH with Fumed Silica (0.007 Micron) Via Shaking
and Formation of a Filled Acrylic Composite Using the Modified
Filler
[0114] The procedures for filler modification and formation of a
filled acrylic composite described in Example 16 were repeated
exactly, except fumed silica of particle size 0.007 microns
(Aldrich) was used as the functional particle. Analysis by SEM
again revealed the presence of small silica particles on the
surface of the ATH (see FIG. 1A (unmodified ATH) versus FIG. 22
(ATH modified with 0.007 micron fumed silica)).
Example 18
Modification of ATH with Talc Via Shaking and Formation of a Filled
Acrylic Composite Using the Modified Filler
[0115] A one-gallon paint can was charged with 1,757.5 g ATH (Alcan
WH-311) and 42.5 g talc, (D.sub.50=10 microns measured by light
scattering, ReactAmine Technology). The vessel was sealed and then
shaken on a Red Devil single-arm paint shaker for 60 minutes. The
sample was a fine free-flowing uniformly white powder.
[0116] The sample was used to cast an experimental Test Plaque
(Test Plaque 18-A). The same formulation, casting procedure, and
plaque finishing procedure as described in Example 13 were used,
except for a substitution with the modified ATH prepared in this
example. The Test Plaque was of high quality, exhibiting uniform
coloration and no visual defects.
[0117] This demonstrates that a filler can be modified with
functional platet-type particles using the processes described
herein.
Example 19
Modification of ATH with Tinuvin 328 Via Shaking and Formation of a
Filled Acrylic Composite Using the Modified Filler
[0118] A one-gallon paint can was charged with 1,757.5 g ATH (Alcan
WH-311) and 42.5 g Tinuvin 328 (BASF). The vessel was sealed and
then shaken on a Red Devil single-arm paint shaker for 60 minutes.
The sample was a fine free-flowing uniformly white powder.
[0119] The sample was used to cast an experimental Test Plaque
(Test Plaque 19-A). The same formulation, casting procedure, and
plaque finishing procedure as described in Example 13 were used,
except for a substitution with the ATH prepared in this example.
The Test Plaque was of high quality, exhibiting uniform coloration
and no visual defects.
[0120] This demonstrates that a filler can be modified with a
crystalline small organic molecule using the processes described
herein.
Example 20
Modification of ATH with FEP Powder Via Shaking and Formation of a
Filled Acrylic Composite Using the Modified Filler
[0121] A one-gallon paint can was charged with 1,757.5 g ATH (Alcan
WH-311) and 42.5 g fluorinated ethylene-propylene copolymer powder
(FEP, DuPont). The vessel was sealed and then shaken on a Red Devil
single-arm paint shaker for 60 minutes. The sample was a fine
free-flowing uniformly white powder.
[0122] The sample was used to cast an experimental Test Plaque
(Test Plaque 20-A). The same formulation, casting procedure, and
plaque finishing procedure as described in Example 13 were used,
except for a substitution with the modified ATH prepared in this
example. The Test Plaque was of high quality, exhibiting uniform
coloration and no visual defects.
[0123] This demonstrates that a filler can be modified with
semicrystalline polymeric particles using the processes described
herein.
Example 21
Modification of ATH with PFA Powder Via Shaking and Formation of a
Filled Acrylic Composite Using the Modified Filler
[0124] A one-gallon paint can was charged with 1,757.5 g ATH (Alcan
WH-311) and 42.5 g perfluoroalkoxy polymer powder (PFA, DuPont).
The vessel was sealed and then shaken on a Red Devil single-arm
paint shaker for 60 minutes. The sample was a fine free-flowing
uniformly white powder.
[0125] The sample was used to cast an experimental Test Plaque
(Test Plaque 21-A). The same formulation, casting procedure, and
plaque finishing procedure as described in Example 13 were used,
except for a substitution with the modified ATH prepared in this
example. The Test Plaque was of high quality, exhibiting uniform
coloration and no visual defects.
[0126] This again demonstrates that a filler can be modified with
semicrystalline polymeric particles using the processes described
herein.
Comparative Example 1
[0127] A control sample was prepared for comparative analysis
against the experimental samples prepared for Examples 22 and 23,
described below. The control sample is a commercially sold
ATH-filled acrylic solid surface material (Corian.RTM., available
from DuPont) composite sheet that is a highly saturated black
color. The material is pigmented with carbon black at a level of
0.058 wt %. The carbon black was introduced to a liquid prepolymer
mixture via a dispersion of general composition known to those
skilled in the art. The control sample was sanded identically to
the experimental samples, as described below in Example 22. After
measuring the color values of the control sample (Table 7) it was
sawn into ten Test Plaques, Comparative Test Plaques 1A, 1B, 1C,
1D, 1E, 1F, 1G, 1H, 1I, and 1J. The control sample provides a
comparison of filled polymeric materials that are pigmented by
traditional liquid dispersions against filled polymeric materials
that are pigmented by dry-blending the pigment and filler prior to
incorporation into a liquid prepolymer mixture, and also to filler
that is dyed before incorporation into a liquid prepolymer
mixture.
Example 22
[0128] Pilot Scale Casting of Filled Acrylic Composition Comprising
ATH Modified with Carbon Black at 0.094 wt. %
[0129] A batch of ATH modified with Arosperse F138 carbon black at
a low level (0.094 wt. %) was made by dry-blending via shaking as
described in Example 3 to make dry-blended carbon black modified
ATH.
[0130] A liquid prepolymer mixture consisting of 2.5 kg methyl
methacrylate (MMA), 10.1 kg of a 24 wt. % acrylic polymer solution
(polymethyl methacrylate of molecular weight approximately 30
kg/mol dissolved in MMA), 152.8 g trimethylolpropane
trimethacrylate, 280.2 g tert-butylperoxymaleic acid (PMA-25,
Arkema), 23.8 g of Zelec PH unsaturated phosphoric acid ester
(Stepan Co.) and 52.5 g AOT-S(Cytec) was blended at room
temperature in a lined, 10-gallon steel vessel using a combination
marine prop/pitch blade turbine impeller. While stirring at 300
rpm, 21.7 kg of the dry-blended carbon black modified ATH described
above was added over one minute. Blending was continued for two
additional minutes. The mixture was then transferred to an enclosed
vessel where dissolved gases were removed in vacuo (24 inHg) over a
period of two minutes while stirring at 500 rpm. While still under
vacuum, 117.7 g of a calcium hydroxide suspension (45 wt. % in
solvent) was added via syringe through a rubber septum. This was
immediately followed by addition of 44.0 g of ethylene glycol
dimercaptoacetate (GDMA). After mixing for 30 seconds, the vacuum
was released and the liquid prepolymer mixture was poured into a
film-lined casting cavity. Film was placed on the backside of the
casting, and an insulated cover was placed on top. The mixture
cured within 15 minutes. After allowing the resultant sheet to cool
to room temperature, it was rough-finished in a drum sander and
then sanded with a sequence of progressively finer grit sand paper
ending with 240-grit to create a low level dry-blended experimental
sample. The experimental sample with a low level of pigment
dry-blended onto filler was of high visual quality, exhibiting
uniform color throughout the specimen, with no blemishes or other
defects.
[0131] Color measurements were made of the low level experimental
sample using a Hunter Miniscan spectrophotometer (Table 3). The
color of the control sample, which had carbon black introduced via
a standard liquid dispersion, and that of the low level
experimental sample made using dry-blended carbon black modified
ATH were approximately the same.
TABLE-US-00005 TABLE 3 Initial Color Values L a b Control Sample
27.07 -0.53 -2.48 Low Level Experimental Sample 26.91 -0.61
-2.68
[0132] The low level experimental sample was then sawn into three
pieces to create Test Plaques 22A, 22B, and 22C.
[0133] Test Plaque 22A and Comparative Test Plaque 1A were
subjected to water blush testing by immersion in 72.degree. C.
water for 16 hours. Color measurements were made on each sample
before and after the test and .DELTA.E values were calculated
(Table 4). The data shows that Comparative Test Plaque 1A had
significantly more whitening due to water blush than was observed
for Test Plaque 22A. This demonstrates that dry-blended filler
provides colored filled polymer materials having improved
resistance to whitening due to water blush.
TABLE-US-00006 TABLE 4 Calculated Color Change After Water Blush
Testing. .DELTA.E Comparative Test Plaque 1A 5.75 Test Plaque 22A
1.18
[0134] Comparative Test Plaque 1B and Test Plaque 22B were
subjected to a thermobending test. Both samples were heated to
160.degree. C. in a double platen oven. Afterwards, they were
placed over a curved form with a 3 inch radius. The specimens were
allowed to cool completely in a vacuum press. The color of the
center region of each sample was read before and after the test.
The results provided in Table 5 below show a significantly lower
color change for Test Plaque 22B compared to Comparative Test
Plaque 1B. This demonstrates that dry-blended filler provides
colored filled polymer materials having improved resistance to
whitening due to thermobending.
TABLE-US-00007 TABLE 5 Calculated Color Change After Thermobending
.DELTA.E Comparative Test Plaque 1B 2.70 Test Plaque 22B 0.64
Example 23
[0135] Pilot Scale Casting of Filled Acrylic Composition Comprising
ATH Dry-blended with Carbon Black at 2.36 wt. %
[0136] A batch of ATH modified by with Arosperse F138 carbon black
at a high level (2.36 wt. %) was made by dry-blending via shaking
as described in Example 3, to make dry-blended carbon black
modified ATH.
[0137] A liquid premix consisting of 2.4 kg methyl methacrylate
(MMA), 9.7 kg of a 24 wt. % acrylic polymer solution (polymethyl
methacrylate of molecular weight approximately 30 kg/mol dissolved
in MMA), 147.0 g trimethylolpropane trimethacrylate, 269.5 g
tert-butylperoxymaleic acid (PMA-25, Arkema), 23.8 g of Zelec PH
unsaturated phosphoric acid ester (Stepan Co.) and 52.5 g
AOT-S(Cytec) was blended at room temperature in a lined, 10-gallon
steel vessel using a combination marine prop/pitch blade turbine
impeller. While stirring at 300 rpm, 22.2 kg of the carbon black
modified ATH described above was added over one minute. Mixing was
continued for two additional minutes. The mixture was then
transferred to an enclosed vessel where dissolved gases were
removed in vacuo (24 inHg) over a period of two minutes while
stirring at 500 rpm. While still under vacuum, 113.2 g of a calcium
hydroxide suspension (45 wt. % in solvent) was added via syringe
through a rubber septum. This was immediately followed by addition
of 42.3 g ethylene glycol dimercaptoacetate (GDMA). After mixing
for 30 seconds, the vacuum was released and the mixture was poured
into a film-lined casting cavity. Film was placed on the backside
of the casting, and an insulated cover was placed on top. The
mixture cured within 15 minutes. After allowing the resultant sheet
to cool to room temperature, it was rough-finished in a drum sander
and then sanded with progressively finer grit sand paper ending
with 240-grit to create a high level experimental sample. The
experimental sample with a high level of pigment dry-blended onto
filler was of high visually quality, exhibiting uniform color
throughout the specimen, with no blemishes or other defects.
[0138] Color measurements were made using a Hunter Miniscan
spectrophotometer (Table 6). The color of the high level
experimental sample was significantly darker than that of the
control sample that was made in Comparative Example 1.
TABLE-US-00008 TABLE 6 Initial Color Values L a b Control Sample
27.07 -0.53 -2.48 High Level Experimental Sample 23.81 -0.39
-1.45
[0139] After measuring the color values of the high level
experimental sample it was sawn into five pieces to create Test
Plaques 23A, 23B, 23C, 23D and 23E.
[0140] Test Plaque 23A and Comparative Test Plaque 1C were
subjected to a water blush test by immersion in 72.degree. C. water
for 16 hours. Color measurements were made after the test and
.DELTA.E values were calculated compared to the initial values
(Table 7). A significant decrease in whitening due to water blush
was observed for Test Plaque 23A as compared to the control of
Comparative Test Plaque 1C. This demonstrates an improvement in
water blush whitening for dry-blended pigment modified filler than
for pigments incorporated by traditional liquid dispersions.
TABLE-US-00009 TABLE 7 Calculated Color Change After Water Blush
Testing. .DELTA.E Comparative Test Plaque 1C 5.75 Test Plaque 23A
0.52
[0141] Test Plaque 23B and Comparative Test Plaque 1D were
subjected to a thermobending test. Both Test Plaques were heated to
160.degree. C. in a double platen oven. Afterwards, the Test
Plaques were placed over a curved form with a 3 inch radius. The
specimens were allowed to cool completely in a vacuum press. The
color of the center region of each Test Plaque was read after the
test and compared to the initial value as shown in Table 6. The
results provided in Table 8 below show a significantly lower color
change for the Test Plaque 23B as compared to the control sample of
Comparative Test Plaque 1D.
TABLE-US-00010 TABLE 8 Calculated Color Change After Thermobending
.DELTA.E Comparative Test Plaque 1D 2.70 Test Plaque 23B 0.20
[0142] A control sample (Comparative Test Plaque 1E), a low level
experimental sample (Test Plaque 22C), and a high level
experimental sample (Test Plaque 23C) were subjected to constant
force scratch testing. A Micro-Scratch Tester (CSM Instruments)
equipped with a 1 mm steel ball was used to scratch each specimen
using a constant force of 15 N over a path length of 20 mm. FIG. 23
shows the resulting scratch on each Test Plaque. The control sample
scratch whitens considerably. While the low level experimental
sample scratch whitens in a similar manner to the control, scratch
whitening is dramatically reduced for the high level experimental
sample. Images of the scratched specimens were analyzed using the
ImageJ software (version 1.45 s) (an image processing program
available from the National Institutes of Health). Histograms of
the grey values found within an area inscribed about each scratch
were generated (FIG. 23). Consistent with the appearance of the
scratches, the control sample and the low level experimental sample
exhibit a population of lighter values while the high level
experimental sample does not. The histogram data are summarized in
Table 9 below. Relative to the control and the low level
experimental sample, the high level experimental sample exhibits a
lower mean grey value, a lower minimum and maximum grey value, and
a lower mode of grey values. Further, a profile plot of the three
samples is given in FIG. 24. This plot shows the grey value along
the scratch from left to right as depicted in FIG. 24. The profile
curve for the high level experimental sample is significantly lower
than that of the control or low level sample.
TABLE-US-00011 TABLE 9 Parameters from Grey Value Histogram (FIG.
24) Low High Control Level Level Count 1788 1800 1812 Mean 56.99
60.43 29.51 Std Dev 34.04 33.22 8.76 Min 30 33 16 Max 170 164 70
Mode 39(225) 42(241) 25(179)
[0143] Control sample Comparative Test Plaque 1E, and experimental
samples Test Plaque 22D and Test Plaque 23D were subjected to an
impact whitening test. A Gardner impact tester fitted with a 2-lb
tip was used to strike each sample successively along its length
with increasing force. A visual determination was made as to the
minimum force required to cause a whitening defect. While the force
required to impart a whitening defect in the control sample was in
the 2-4 in-lb range, the force required to impart a whitening
defect in the experimental sample was in the 6-8 in-lb range
indicating a resistance to whitening due to impact. This
demonstrates an improvement in impact whitening for dry-blended
pigment modified filler compared to pigments incorporated by
traditional liquid dispersions.
[0144] Control sample Comparative Test Plaque 1F and the
experimental sample Test Plaque 23E were subjected to a temperature
resistance test. A heated block, thermostatically controlled to
250.degree. C., was placed on the surface of each sample for 5
minutes. The color of the sample where the test was conducted was
read before and after. Table 10 below shows a significant
difference in whitening due to incidence with high temperature for
the experimental sample versus the control (3.98 versus 13.02
.DELTA.E units). FIG. 25 depicts the appearance of each sample
before and after the test. The results provided in Table 10 below
show a significantly lower color change for the Test Plaque 23E as
compared to the control sample of Comparative Test Plaque 1F. This
demonstrates an improvement in high temperature whitening for
dry-blended pigment modified filler compared to pigments
incorporated by traditional liquid dispersions.
TABLE-US-00012 TABLE 10 Calculated Color Change After Hot Block
Testing .DELTA.E Comparative Test Plaque 1F 13.02 Test Plaque 23E
3.98
Comparative Example 2
[0145] A dyed aluminum trihydrate filler was synthesized as
described in Example 2 of U.S. Pat. No. 7,863,369. A four liter
reaction kettle was charged with an aqueous suspension of Alumina
Trihydrate (ATH, Rio-Tinto-Alcan, WH311-540 g) in de-ionized water
(3,377 g). The pH of the aqueous suspension was adjusted to
.about.3.5 using a dilute solution of nitric acid in water
(.about.1 mL of a 14% solution). Reactive Red 198 powder (4.22 g,
Reactive Red 198 is a triazine dye having a sulfatoethylsulfone
functional group, and was obtained from Organic Dyestuffs Corp,
1015 Highway 29 N, Concord, N.C. 28025, Product No. 16198OR12) was
added to the reaction kettle. The resulting ATH-dye suspension was
warmed to 65.degree. C. for a one hour interval with constant
stirring. The aqueous suspension was maintained at a temperature of
between 60.degree. C. and 70.degree. C. for two hours with constant
stirring. After the two hour heating interval was complete, the
suspension was allowed to cool and settle overnight without
stirring. Excess liquid was decanted from the settled ATH, and the
moist solid obtained was dried at 60.degree. C. to 70.degree. C.
first in a hot air oven and then under vacuum (>740 mm Hg). Any
agglomerates which formed during the drying steps were broken up by
ball milling with ceramic media.
[0146] A dyed-filler control sample of filled polymeric material
comprised of an acrylic matrix and dyed aluminum trihydrate filler
was synthesized in a 1500 mL resin kettle (10.5.times.23 cm) fitted
with kettle top having ports for a temperature probe, air-driven
stirrer, rubber septum and an Allihn.TM. type reflux condenser. The
following ingredients were sequentially weighed into the
kettle:
PMA-25 (t-Butyl Peroxymaleic Acid Paste, Arkema) 17.16 g
Aerosol-OT Surfactant (Cytec Industries) 2.74 g
TRIM (Trimethylolpropane Trimethacrylate, Sartomer) 7.46 g
MMA (Methyl Methacrylate, Lucite.RTM. International 56.07 g
[0147] Zelec.RTM. PH (unsaturated phosphoric acid ester, Stepan Co)
1.23 g Polymer Syrup (24% PMMA-30,000 Daltons dissolved in MMA)
587.35 g
Quinacridone Red Pigment Paste (Penn Color, PC9S172) 6.84 g
[0148] After mixing these ingredients using a High Speed Disperser
(HSD) Blade (60 mm Diameter-INDCO Cowles Type) at 500 rpm for one
minute at room temperature, 1116.0 g of dyed ATH (prepared as
described above) was added portion wise over a two minute interval.
During the portion wise addition of the dyed ATH, the rpm of the
HSD was incrementally increased to about 1,500 rpm. After the dyed
ATH addition was complete, the HSD speed was increased to 2,000 rpm
and maintained for 10 minutes. The resulting mixture was then
evacuated (Reflux condenser cooled to -10.degree. C.) at 75 Torr
(about 27 inches of Hg) for two minutes with 1,000 rpm stirring
(3'-four blade prop). The mixture was warmed to 45.degree. C. using
a waterbath. The mixing rpm was increased to 1,500 rpm and the
following ingredients were sequentially injected via syringe in
rapid succession: De-mineralized water 0.25 g
Calcium Hydroxide (45% Suspension, DuPont) 7.21 g
Thiocure.RTM. GDMA (Glycol Dimercaptoacetate, Evans) 2.69 g
[0149] The resulting slurry was allowed to mixture (1,500 rpm) at
45.degree. C. for about 10 sec. Stirring was discontinued and the
vacuum was released with air. The initiated mixture was poured into
a 15 mm thick sheet casting mold within a one minute interval. The
time required to achieve a peak temperature of 138.degree. C. was
approximately 6 minutes. The addition of the GDMA was considered
"Time Zero". Upon cooling, the hardened, polymerized composite
plaque was removed from the mold after about one hour and
rough-finished on a drum sander and then sanded with progressively
finer grit sand paper ending with 240-grit to create a dyed-filler
control sample. After measuring the color values of the dyed-filler
control sample it was sawn into four Test Plaques, Comparative Test
Plaques 2A, 2B, 2C, and 2D.
Color Change Due to Hot Water Immersion (Water Blush Testing)
[0150] Comparative Test Plaque 1G as a control sample, and
Comparative Test Plaque 2A as the experimental sample were
subjected to a water blush test by immersion in 72.degree. C. water
for 16 hours. Color measurements were made on each sample after the
immersion and .DELTA.E values were calculated (Table 11).
Comparative Test Plaque 2A (dyed ATH) exhibits a significantly
larger color change after hot water immersion, compared to the
control (Comparative Test Plaque 1G--liquid dispersion).
TABLE-US-00013 TABLE 11 Calculated Color Change after Hot Water
Immersion .DELTA.E Comparative Test Plaque 1G 1.99 Comparative Test
Plaque 2A 9.56
Degree of Whitening Due to Thermobending
[0151] Comparative Test Plaque 1H as a control sample, and
Comparative Test Plaque 2B as the experimental sample were
subjected to a thermobending test. Each piece was heated to
160.degree. C. in a double platen oven. Afterwards, the specimens
were placed over a curved form with a 3 inch radius. The Test
Plaques were allowed to cool completely in a vacuum press. The
color of the center region of each Test Plaque was read before and
after the test. The results provided in Table 12 below indicate
that there is no significant difference in the color change due to
thermobending between each sample.
TABLE-US-00014 TABLE 12 Calculated Color Change After Thermobending
.DELTA.E Comparative Test Plaque 1H 2.56 Comparative Test Plaque 2B
3.10
Degree of Scratch Whitening
[0152] Comparative Test Plaque 1I and Comparative Test Plaque 2B
were subjected to constant force scratch testing. A Micro-Scratch
Tester (CSM Instruments) equipped with a 1 mm steel ball was used
to scratch each specimen using a constant force of 15 N over a path
length of 20 mm. FIG. 26 shows the resulting scratch on each
specimen. Both the liquid dispersion sample (Comparative Example
1I) and the sample made using the dyed filler (Comparative Example
2B) scratch-whiten considerably. Images of the scratched Test
Plaques were analyzed using the ImageJ software (version 1.45 s).
Histograms of the grey values found within an area inscribed about
each scratch were generated (FIG. 26). Consistent with the
appearance of the scratches, both Test Plaques exhibit a
significant population of lighter values. The histogram data are
summarized in Table 13 below. While the mean grey value of the
liquid dispersion sample is somewhat higher than the dyed ATH
sample, the latter has a higher maximum grey value. A profile plot
of both samples is given in FIG. 27. This plot shows the grey value
along the scratch from left to right as depicted in FIG. 26. The
profile curves of the scratches of the two samples are quite
similar. When all of the visual data is taken together, it can be
concluded that no appreciable difference in the intensity of
scratch whitening exists.
TABLE-US-00015 TABLE 13 Parameters from Grey Value Histogram (FIG.
26) Liquid Dyed Dispersion ATH Count 1800 1800 Mean 122.167 104.873
Std Dev 32.353 42.232 Min 93 65 Max 232 242 Mode 106(127)
80(128)
Degree of Whitening Due to High Temperature
[0153] Comparative Test Plaque 1J and Comparative Test Plaque 2C
were subjected to a temperature resistance test. A heated block,
thermostatically controlled to 250.degree. C., was placed on the
surface of each sample for 5 minutes. The color of the Test Plaques
were measured after the hot block was removed. The results provided
in Table 14 below indicate that there is no significant difference
in the color change due to incidence with high temperature between
each sample.
TABLE-US-00016 TABLE 14 Calculated Color Change after Hot Block
Test .DELTA.E Comparative Test Plaque 1J 1.99 Comparative Test
Plaque 2C 9.56
* * * * *