U.S. patent application number 09/850179 was filed with the patent office on 2001-09-27 for water soluble rapid prototyping support and mold material.
This patent application is currently assigned to Stratasys, Inc.. Invention is credited to Artz, Gregory John, Lombardi, John Lang, Popovich, Dragan.
Application Number | 20010025073 09/850179 |
Document ID | / |
Family ID | 26767003 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010025073 |
Kind Code |
A1 |
Lombardi, John Lang ; et
al. |
September 27, 2001 |
Water soluble rapid prototyping support and mold material
Abstract
Formation of polymeric prototype elements is effected by high
pressure and high temperature extrusion of selected materials onto
a plate as a ribbon of liquefied polymer comprising
poly(2-ethyl-2-oxazoline) and a polar polymer discharged in a
programmed pattern.
Inventors: |
Lombardi, John Lang;
(Tucson, AZ) ; Popovich, Dragan; (Tucson, AZ)
; Artz, Gregory John; (Tucson, AZ) |
Correspondence
Address: |
KINNEY & LANGE, P.A.
THE KINNEY & LANGE BUILDING
312 SOUTH THIRD STREET
MINNEAPOLIS
MN
55415-1002
US
|
Assignee: |
Stratasys, Inc.
Eden Prairie
MN
|
Family ID: |
26767003 |
Appl. No.: |
09/850179 |
Filed: |
May 7, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09850179 |
May 7, 2001 |
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09096100 |
Jun 11, 1998 |
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6228923 |
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09096100 |
Jun 11, 1998 |
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09082064 |
May 20, 1998 |
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6070107 |
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09082064 |
May 20, 1998 |
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08825893 |
Apr 2, 1997 |
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6067480 |
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Current U.S.
Class: |
524/425 ;
524/449; 524/451; 524/492; 524/495 |
Current CPC
Class: |
C08K 3/26 20130101; C08L
55/02 20130101; C08K 3/013 20180101; C08L 79/02 20130101; C08L
53/00 20130101; C08L 2666/02 20130101; C08L 2666/02 20130101; B33Y
70/00 20141201; C08L 55/02 20130101; C08K 3/01 20180101; C08L 53/00
20130101 |
Class at
Publication: |
524/425 ;
524/449; 524/451; 524/492; 524/495 |
International
Class: |
C08K 003/26; C08K
003/34; C08K 003/04 |
Claims
1. A thermoplastic polymer in the form of an extrudable object
comprising in combination a filament of poly(2-ethyl-2-oxazoline)
and a polar polymer selected from the group consisting of compounds
having nitrile functional groups, compounds having ether and
hydroxyl functional groups, and mixtures thereof.
2. A thermoplastic composition suitable for three-dimensional
modeling, comprising poly(2-ethyl-2-oxazoline) and a polar polymer
selected from the group consisting of compounds having nitrile
functional groups, compounds having ether and hydroxyl functional
groups, and mixtures thereof.
3. The thermoplastic composition of claim 2, wherein the polar
polymer is selected from the group consisting of a linear
thermoplastic phenoxy oligomer blend and a styrene-acrylonitrile
copolymer.
4. The thermoplastic composition of claim 2, and further comprising
a plasticizer.
5. The thermoplastic composition of claim 4, wherein the
plasticizer is a water-soluble alcohol plasticizer.
6. The thermoplastic composition of claim 2, and further comprising
an inert filler.
7. The thermoplastic composition of claim 6 wherein the inert
filler is selected from the polymer filler group consisting of
calcium carbonate, glass spheres, graphite, carbon black, carbon
fiber, glass fiber, talc, wollastonite, mica, alumina, silica and
silicon carbide.
8. The thermoplastic composition of claim 5, and further comprising
an inert filler.
9. The thermoplastic composition of claim 8, wherein the inert
filler is selected from the polymer filler group consisting of
calcium carbonate, glass spheres, graphite, carbon black, carbon
fiber, glass fiber, talc, wollastonite, mica, alumina, silica and
silicon carbide.
10. The thermoplastic composition of claim 2, in the form of an
extrudable object.
11. The thermoplastic composition of claim 10, wherein the
extrudable object is a filament.
12. The thermoplastic composition of claim 10, wherein the
extrudable object is a slug.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This is a divisional of U.S. application Ser. No.09/096,100,
filed Jun. 11, 1998; which is a continuation in part of U.S.
application Ser. No. 09/082,064, filed May 20, 1998, now U.S. Pat.
No. 6,070,107; which is a continuation in part of U.S. application
Ser. No. 08/825,893, filed Apr. 2,1997, now U.S. Pat. No.
6,067,480; all of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to thermoplastic polymer materials
for the preparation of three-dimensional prototypes or models.
Prototypes of parts are made and used in testing in a wide-variety
of industries, such as the automobile, aerospace, and biomedical
prostheses manufacturing industries. After successful testing the
prototypes of parts, a mold of the prototype can be made and the
part can be manufactured on a mass production basis.
[0003] There are three ways of making prototypes. One method
involves simply making a mold of the part, making the prototype,
and then testing the prototype. However, this method requires the
cost of making a mold, which itself can be extremely expensive and
time-consuming. Moreover, this method may require numerous molds to
be made on a trial and error basis until a successful part has been
designed that sufficiently passes the required testing.
[0004] A second method of making prototypes involves sculpting a
three-dimensional prototype of a particular shape from a block work
piece. In this method, the prototype is drawn either manually or
using computer-aided design (CAD) techniques, and the prototype is
formed by removing material from a block work piece. The part can
be further machined either manually or using computer-aided
machining (CAM) techniques. However, this method can also be a
costly and time-consuming process because it may require repeated
iterations until a desired prototype is made.
[0005] A third method that has been developed involves the
formation of a three-dimensional prototype by depositing multiple
layers of a material in a fluid state onto a base. The fluid
solidifies to define the prototype element. In general this method
is often termed freeforming in the prior art. For example, such a
method is taught in U.S. Pat. No. 5,340,433, and U.S. Pat. No.
5,121,329, both issued to S. Scott Crump and assigned to Stratasys,
Inc. incorporated herewith by reference. In this method, a layer of
the fluid material solidifies and then another layer of fluid
material is deposited over the preceding layer. The thickness of
each layer is controlled by the distance between the tip of the
dispensing head and the preceding layer. However, there are a
number of disadvantages to the method and apparatus taught in this
third method because only certain types of materials can be
suitably used to make the prototypes, such as waxes having low melt
viscosity and strength. Thermoset materials may be used to try to
improve strength and toughness. In any event, this prior art
deposition method may not produce durable prototypes made from high
performance engineering polymers and composites.
[0006] There is a clear need for a method and apparatus that can
make stronger and tougher prototypes made of engineering polymers
and composites having high melt viscosity and long chain lengths.
Such a method and apparatus is disclosed in U.S. Pat. No.
6,067,480, which is incorporated herein by reference.
[0007] As noted in U.S. Pat. No. 6,067,480, materials for high
pressure fused deposition include polyaryletherketone (PEEK.RTM.
produced by Victrex), polmethylmethacrylate (PMMA.RTM. produced by
DuPont), polycarbonate (Lexan.RTM. made by General Electric
Plastics), thermoplastic polyurethane (Pellethane(.RTM. made by Dow
Chemical), and polylatic acid/polyglycolic acid block copolymer (a
bio-absorbable material made by a Biomet joint venture). Fused
deposition of fiber reinforced grades of engineering polymers and
composites, for example PEEK.RTM. and Lexan.RTM. can also be used
for the invention disclosed in U.S. Ser. No. 08/825,893. Moreover,
prototypes can be made in accordance with that invention using
fiber reinforcement. For example, carbon fiber reinforced PEEK.RTM.
materials had a tensile strength of over 36,000 psi, exhibited a
very high fracture toughness and demonstrated highly anisotropic
mechanical properties whereas unreinforced materials did not.
[0008] Thus, there is a clear need for strong materials that can be
used in a method for making prototypes, and in particular materials
for the method involving the depositing of multiple layers in a
fluid state onto a base. More specifically, there is a need for
strong thermoplastic polymers that can be easily melt extruded by
an extrusion freeforming apparatus in layer form, and which then
solidify upon cooling so that complicated shaped parts can be
freeform fabricated by precisely and sequentially depositing
polymer layers upon one another until the desired component is
produced. There is also a need for strong materials that can be
used as a support material for use in an extrusion freeforming
apparatus that prevents the sagging of deposited molten, prototype
material layers before cooling and solidification. Support
materials are particularly important when fabricating complex
geometry, dimensionally accurate prototypes having numerous
overhangs, or internal cavity features.
BRIEF SUMMARY OF THE INVENTION
[0009] In the present invention, a unique thermoplastic polymer
material, i.e., poly(2-ethyl-2-oxazoline) (referred to hereafter as
"PEO"), is used as a polymer layer material as well as a support
material in a freeform fabrication process. More specifically, PEO
is melt extruded by a freeforming apparatus in layer form. The PEO
layers solidify upon cooling and complicated shaped parts can be
freeform fabricated by precisely and sequentially depositing
polymer layers upon one another until the desired component is
produced. Thus, prototypes can be directly free formed by an
extrusion freeforming apparatus using PEO as a raw material.
[0010] In addition, in the present invention, PEO is used as a
support material for use in rapid prototype processes such as
extrusion freeform fabrication or a a fused deposition modeling
process. In particular, many parts which are fabricated by these
processes have complicated overhang geometries which require the
use of a support material that prevents the sagging of deposited
molten, prototype material layers before cooling and
solidification.
[0011] It has been discovered that a major advantage of PEO over
other materials is that PEO is a high strength rigid thermoplastic
polymer that is easily and accurately extruded and has a good slump
resistance at temperatures less than about 200.degree. C. PEO also
has the added benefits in that it is essentially an amorphous
polymer that does not undergo significant shrinkage upon
solidification. Polyethylene oxide, another commercially available
water soluble thermoplastic, on the other hand, undergoes
approximately 15-20% shrinkage due to crystallization upon
solidification. Shrinkage on the order of this magnitude puts a
great deal of stress and may induce warpage in free formed support
material layers. PEO also has high degree of interlayer adhesion
when free formed. Polyethylene oxide has negligible interlayer
adhesion when free formed. A major benefit of using PEO is that it
has all of the above properties coupled with high water solubility.
Rapid prototype parts can therefore be fabricated using PEO as a
support material and the PEO support can be easily washed away with
water from the completed prototype part without employing toxic and
environmentally detrimental solvents, which may also dissolve the
desired polymer prototype part. It is believed that PEO is the only
commercially available non-ionic water soluble thermoplastic
material (sold under the tradename Aquazol by Polymer Chemistry
Innovations Inc., of Tucson, Ariz.) that has all of the above
properties. PEO is also very tacky and many materials readily
adhere to it, thereby making PEO an excellent rapid prototyping
support material.
[0012] Furthermore, PEO is not as hygroscopic compared to other
commercial water soluble polymers including polyvinyl alcohol and
polyethylene oxide, and thus PEO possesses significantly greater
dimensional stability in ambient humid atmosphere compared to these
other polymers. Moreover, PEO can be extruded at higher
temperatures without decomposing and having its melt viscosity
change with time.
[0013] In another aspect of the present invention, PEO is used as a
fugitive mold material for casting ceramic slurries, e.g. for
ceramic green body fabrication, and also preparing polyurethane or
epoxy parts by pouring reactive mixtures of these liquid precursor
materials into a mold which is precision machined from bulk PEO
stock. Thus, in accordance with the present invention, parts can be
subsequently extracted from the mold by placing the entire part in
a water bath after the slurry or precursors are cured so that the
water dissolves the PEO and leaves the fabricated polymer or green
ceramic part behind.
[0014] This unique polymer PEO, not heretofore suggested for use
asan extrusion freeform fabrication material, greatly facilitates
the extrusion free form fabrication of parts, as well as for
casting ceramic slurries.
[0015] These and other objects, advantages and features of the
present invention will be more fully understood and appreciated by
reference to the detailed description which follows.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] PEO as Cylindrical Feed Rod Material
[0017] In a preferred embodiment of the present invention, the
specific thermoplastic polymer material poly(2-ethyl-2-oxazoline),
i.e., PEO, was prepared as a slug in the form of a cylinder having
the following dimensions: 0.3 875 inches in diameter by 5.50 inches
in length.
[0018] Thereafter, the slug was inserted into an apparatus, the
type described in U.S. Pat. No. 6,067,480 and extruded as a fine
ribbon by said apparatus to form a prototype mechanical element or
object. More specifically, the steps performed comprised the steps
of:
[0019] a) positioning a cylindrical rod of said polymer material
comprising PEO in a cylindrical housing having a throughbore with a
diameter substantially equal to the diameter of the cylindrical
rod, said housing being connected with and attached to a discharge
head member having a uniform diameter bore connecting with the
throughbore, a discharge tip, a reduced diameter discharge opening
in the tip, and a circumferential heater to liquefy the material in
the bore;
[0020] b) compressing the material in the housing with a piston
while simultaneously liquefying the material in the head member to
thereby discharge a ribbon of material from the tip;
[0021] c) transporting the platform in the x and y directions while
discharging material thereon to form the cross sectional shape of
the element; and
[0022] d) transporting the housing and head member in the z
direction simultaneously to form the element in elevation. The
extrusion occurred in multiple layers of a ribbon of the material
discharged from the nozzle of the apparatus layer upon layer so as
to form the object.
[0023] The polymer material comprising PEO can be used as a support
for free formed layers of other material. Further, the method of
the present invention can be used to make an article of manufacture
that is a free form three-dimensional object comprising a plurality
of layers of a ribbon of PEO. The present invention further
includes a thermoplastic polymer in the form of an extrudable
object comprising a slug of PEO.
[0024] At least one inorganic filler can be added to the polymer
material comprising PEO. The inorganic filler can be comprised of
at least one soluble salt. Examples of soluble salts include alkali
or alkaline earth halides (e.g., sodium chloride, magnesium
chloride) or their sulfates (e.g., magnesium sulfate).
[0025] The PEO can be blended with at least one inert filler. The
inert filler can be selected from the polymer filler group
consisting of calcium carbonate, glass spheres, graphite, carbon
black, carbon fiber, glass fiber, talc, wollastonite, mica,
alumina, silica and silicon carbide.
[0026] The typical extrusion temperature of the polymer in the head
member can be in the range of about 120-410.degree. C., and is
preferably in the range of 150-200.degree. C., and most preferably
approximately 175.degree. C. The rod is compressed and extruded at
a pressure of about 200-1,000 psi, and is preferably compressed and
extruded at a pressure in a range of about 500-700 psi.
[0027] Tensile test bar specimens were extrusion free-formed in
accordance with ASTM D638 testing standard using both 200,000 and
50,000 molecular weight (MW) Aquazol feedrods. These specimens were
tested and compared with objects made using similar apparatus. The
various objects, i.e., prototype mechanical elements, were then
tested and compared one to the other and the test results are
reported below.
[0028] Mechanical Testing
[0029] Mechanical tests were carried out on polymer resins
manufactured into test configurations in accordance with the same
extrusion freeforming fabrication process previously referred to
above. Samples were tensile tested to determine their strengths,
moduli and elongation to break values. The polymers tested were the
PEO of the present invention, ABS and Nylon- 11. The test results
are shown in Table I along with reported test results of other
materials. In addition to mechanical testing, sample tensile
properties were measured and compared to reported properties of the
other materials.
[0030] Tensile Testing
[0031] Tensile tests were performed as close to standard ASTM D638
as possible. Tensile bars were free formed and tested without
further machining or modification. The test specimen geometry was
of the typical "dog bone" shape. Machining the bars resulted in
damage to the gauge section of some materials. Since tensile
testing is very sensitive to notches, machining was not
possible.
[0032] Samples were tested along the writing direction. This simply
denotes the bead direction with respect to the mechanical testing
equipment. The equipment used was a model 1011 Instron apparatus
with a load cell capacity of 1000 pounds. The 1011 Instron
apparatus uses vertical specimen loading and wedge-action type
grips. The cross head speed for all specimens was 0.2 inches per
minute.
[0033] Tensile moduli strength, 0.2% yield strength, and elongation
or strain to fracture were calculated.
[0034] Discussion of Results
[0035] The values contained in Table I resulted from averaging the
test samples' measured properties of interest.
[0036] The mechanical properties of the materials prepared in this
work are compared with other free formed polymer materials in Table
I. The PEO is more than 30 percent stronger and between 2 to 3
times stiffer than any of the presently available water soluble
polymer materials. These properties represent a substantial
improvement in the art.
1TABLE 1 Comparison of Materials Properties from Commercial SFF
Systems .sigma. tensile tensile .epsilon. break System Material
Grade (psi) (ksi) (%) 3D Epoxy XB5170 2,400 130 9 DTM Nylon-11
LN4000 5,200 200 32 Stratasys ABS 5,000 360 50 ACR PEEK 450 FC
36,374 1195 3 ACR Poly- Union Carbide 3,000 40-70 500 ethylene
Polyox WSR- oxide N80 (200,000 MW) ACR PEO Aquazol 200 4,000 230
1.9 (200,000 MW) ACR PEO Aquazol 50 900 150 0.9 (50,000 MW) wherein
MW = molecular weight SFF = Solid Free-Forming 3D = 3D Systems of
Valencia, California DTM = DTM Corporation of Austin, Texas
Stratasys = Stratasys of Eden Prairie, Minnesota ACR = Advanced
Ceramics Research, Inc. of Tucson, Arizona
[0037] PEO in Filament Applications
[0038] PEO has been found to be not only useful as cylindrical feed
rod material, but also as filament feed material in yet another
preferred embodiment of the present invention. It has been
discovered that PEO is an excellent filament feed material that can
be free formed using fused deposition modeling processes taught in
U.S. Pat. No. 5,340,433 and U.S. Pat. No. 5,121,329 because it is
water soluble and can be washed away easily, is a stiff material,
is thermally stable, and adheres well to other materials, including
other layers of PEO. Therefore, PEO filament feedstock can be used
as a support material in fused deposition modeling of polymer
prototype parts.
[0039] Thus, the present invention includes a method for forming
prototype mechanical elements from at least one polymer material on
a platform comprising the steps of:
[0040] a) placing filament containing said polymer material
comprising poly(2-ethyl-2-oxazoline) in a cylindrical housing
having a throughbore with a diameter substantially equal to the
diameter of the filament, said housing being connected with and
attached to a discharge head member having a uniform diameter bore
connecting with the throughbore, a discharge tip, a reduced
diameter discharge opening in the tip, and a circumferential heater
to liquefy the material in the bore;
[0041] b) liquefying the material in the head member to thereby
discharge a ribbon of material from the tip;
[0042] c) transporting the platform in the x and y directions while
discharging material thereon to form the cross sectional shape of
the element; and
[0043] d) transporting the housing and head member in the z
direction simultaneously to form the element in elevation.
[0044] The polymer material comprising PEO can be used as a support
for free formed layers of other material. Further, the method of
the present invention can be used to make an article of manufacture
that is a free form three-dimensional object comprising a plurality
of filament layers of PEO. The present invention further includes a
thermoplastic polymer in the form of an extrudable object
comprising a filament of PEO.
[0045] Further it has now been discovered that PEO can be blended
with a variety of polar thermoplastics, fillers, and plasticizers
to modify its physical properties. These additives enable the PEO
polymer to be extruded into tough, flexible geometries (including
Stratasys Fused Deposition Modeller (FDM.RTM.) filament form).
[0046] The polymer material comprising PEO can also include an
inorganic filler, which in turn can be comprised of at least one
soluble salt.
[0047] The PEO can be blended with at least one inert filler. The
inert filler can be selected from the polymer filler group
consisting of calcium carbonate, glass spheres, graphite, carbon
black, carbon fiber, glass fiber, talc, wollastonite, mica,
alumina, silica and silicon carbide.
[0048] The typical extrusion temperature of the polymer in the head
member can be in the range of about 120-410.degree. C., and is
preferably in the range of 150-290.degree. C., and most preferably
approximately 180.degree. C.
[0049] As a further example, the modulus of PEO can be decreased by
the addition an alcohol plasticizer. Preferably the alcohol
plasticizer is in an amount of 0.5 to 45 wt. % alcohol plasticizer
to the PEO. Preferred alcohol plasticizers are water soluble and
have structures composed of multiple hydroxyl groups (i.e.,
ethylene glycol, glycerol or 200-10,000 MW Union Carbide PEG
polyethylene glycols). 600 MW PEG is a preferred plasticizer due to
its combination of low viscosity and low melting point. These
plasticizers decrease the rigidity of PEO and enable it to be drawn
into flexible filament feedstock that can be extruded by a
Stratasys Fused Deposition Modeller (FDM(.RTM.) machine.
Furthermore, PEG plasticizers are miscible with water and are
believed to enhance the overall water solubility and dissolution
rate of the free formed plasticized PEO material.
[0050] PEG plasticized PEO filament is highly tacky in humid
atmosphere, which makes it difficult to uniformly spool as feed
material through the Stratasys FDM.RTM. machine dispensing head.
Consequently, its formulation must be modified to decrease its
tackiness as well as enhance its strength. Addition of 0.25 -5 wt.
% of polar wax has been shown to decrease filament tackiness. The
polar wax can be selected from the group consisting of compounds
having alcohol, acid, ester or amide functional groups. Thus, in
the present invention it is contemplated that among the various
compounds that can be used include, but are not limited to amide
waxes, including oleamide and stearamide, stearic acid, and
stearate/oleate esters. In particular, an ethoxylated fatty alcohol
known under the tradename of Unithox 420 (Baker Petrolite
Corporation, Tulsa, Okla.) has been found to reduce filament
tackiness. The structure of Unithox 420 is given below:
CH.sub.3CH.sub.2(CH.sub.2CH.sub.2).sub.xCH.sub.2CH.sub.2(O
CH.sub.2CH.sub.2).sub.yOH
[0051] where x/y ranges from 4-10, but the preferred ratio is about
5.2
[0052] Unithox 420 is believed to be uniformly soluble in the PEG
plasticized PEO at elevated temperatures but phase separates from
the mixture and migrates to the extruded filament surface upon
cooling. This leaves a slightly waxy, low tackiness surface upon
the cooled filament.
[0053] Polar homopolymers and copolymers containing polar
functional groups, either pendant to or present in its main chain,
can be added to PEG plasticized PEO formulations in order to
increase the strength and toughness of the filament. Examples of
polar homopolymers and copolymers that can be added to the PEG
plasticized poly(2-ethyl-2-oxazoline) include Nylon 12, amorphous
nylon copolymer of terephthalamide/isophthala-
mide/hexamethylenediamide, Nylon 6/Nylon 12 copolymer,
polyvinylformal, polyvinylbutyral and polyesters. These polymers
also decrease the tendency of the filament to fracture when it is
fed through the rollers on the Stratasys FDM.RTM. machine head.
Examples of polyamides include Nylon 12 (Grilamid L16) and an
amorphous nylon copolymer of
terephthalamide/isophthalamide/hexamethylenediamide (Grivory G16),
both manufactured by EMS American Grilon Inc., Sumter, S.C., and
Nylon 6/Nylon 12 Copolymer (Vestamelt 430P-1), made by
Huls/Creanova Inc., Somerset, N.J. These polyamides can be present
in amounts ranging from 0.5-35 wt. % based upon the total mass of
PEG plasticized PEO.
[0054] Specific examples of water soluble plasticized PEO
compositions that can be extruded into flexible filament and
successfully extruded through a Stratasys FDM head presented
below:
2 EXAMPLE I Calcium Carbonate* 22.3 wt. % PEO (200K MW) 65.0 PEG
(600 MW) 8.6 Grilamid LI 6 4.1 EXAMPLE II Calcium Carbonate* 59.1
PEO (50K MW) 26.9 PEG (600 MW) 11.1 Vestamelt 43OP-1 2.9 EXAMPLE
III Calcium Carbonate* 26.1 PEO (200K MW) 57.5 PEG (600 MW) 10.-0
Grilamid LI 6 4.9 Unithox 1.5 EXAMPLE IV Calcium Carbonate* 22.4
PEO 50K MW) 60.9 PEG (600 MW) 6.9 Grivory G- 16 Nylon 6.7 Unithox
420 3.1 EXAMPLE V CaCO.sub.3 59.25 PEO (200K MW) 26.25 PEG (600 MW)
10.80 Polyvinylbutyral** 3.70 EXAMPLE VI CaCO.sub.3 25.98 PEO (200K
MW) 58.96 PEG (600 MW) 8.35 Phenoxy PKHM 301*** 3.70 Unithox 420
1.52 EXAMPLE VII CaCO.sub.3 26.09 PEO (200K MW) 59.23 PEG (600 MW)
8.39 Tyril 125**** 4.76 Unithox 420 1.53 *Calcium Carbonate filler
was a submicron precipitated powder known under the tradename of
Multifex MM 1007/056, made by Specialty Minerals Inc., Adams, MA.
**Polyvinylbutyral used is known under the tradename Bulvar B-98
made by Mansanto Company of St. Louis, MO. ***Phenoxy PKHM 301 is a
linear thermoplastic phenoxy resin oligomer blend obtained from
Phenoxy Specialists (Division in InChem Corp.), Rock Hill, SC.
***Tyril 125 is a styrene-acrylonitrile (SAN) copolymer
manufactured by Dow Chemical Corp., Midland, MI. Preferred SAN
copolymers have an amount ranging from about 20-40 wt. %
acrylonitrile repeat units present in the polymer chains.
[0055] Polyvinylbutyral used is known under the tradename Butvar
B-98, made by Monsanto Company of St. Louis, Mo.
[0056] Phenoxy PKHM 301 is a linear thermoplastic phenoxy resin
oligomer blend obtained from Phenoxy Specialists (Division in
InChem Corp.), Rock Hill, S.C.
[0057] Tyril 125 is a styrene-acrylonitrile (SAN) copolymer
manufactured by Dow Chemical Corp., Midland, Mich. Preferred SAN
copolymers have an amount ranging from about 20-40 wt. %
acrylonitrile repeat units present in the polymer chains.
[0058] Examples VI and VII are believed to provide the most
preferred embodiments of the present invention in that they are the
easiest to formulate, and both exhibit excellent fluidity
characteristics. Thus, it is preferred that the polar polymer added
to the PEO is a polar polymer selected from the group consisting of
compounds having nitrile functional groups (like Example VII) or
compounds having ether and hydroxyl functional groups (like Example
VI). Further, the linear thermoplastic phenoxy resin oligomer blend
of Example VI and the styrene-acrylonitrile copolymer of Example
VII each exhibited a high degree of thermodynamic compatibility
with PEO polymers.
[0059] Those of skill in the art will recognize various changes to
the methods, materials, component ratios, and apparatus are
possible without departing from the spirit and scope of the
invention. Thus, the invention is to be limited only by the claims
and equivalents thereof.
[0060] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *