U.S. patent application number 13/690945 was filed with the patent office on 2013-06-13 for cellulose esters in highly-filled elastomaric systems.
This patent application is currently assigned to Eastman Chemical Company. The applicant listed for this patent is Eastman Chemical Company. Invention is credited to Soumendra Kumar Basu, Bradley James Helmer.
Application Number | 20130150501 13/690945 |
Document ID | / |
Family ID | 48572573 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130150501 |
Kind Code |
A1 |
Basu; Soumendra Kumar ; et
al. |
June 13, 2013 |
CELLULOSE ESTERS IN HIGHLY-FILLED ELASTOMARIC SYSTEMS
Abstract
An elastomeric composition is provided comprising at least one
primary elastomer, one or more fillers, and at least one non-fibril
cellulose ester, wherein the elastomeric composition exhibits a
dynamic mechanical analysis (DMA) strain sweep modulus as measured
at 5% strain and 30.degree. C. of at least 1,450,000 Pa and a
molded groove tear as measured according to ASTM D624 of at least
125 lbf/in.
Inventors: |
Basu; Soumendra Kumar;
(Johnson City, TN) ; Helmer; Bradley James;
(Kingsport, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eastman Chemical Company; |
Kingsport |
TN |
US |
|
|
Assignee: |
Eastman Chemical Company
Kingsport
TN
|
Family ID: |
48572573 |
Appl. No.: |
13/690945 |
Filed: |
November 30, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61567948 |
Dec 7, 2011 |
|
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|
61567950 |
Dec 7, 2011 |
|
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61567953 |
Dec 7, 2011 |
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61567951 |
Dec 7, 2011 |
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Current U.S.
Class: |
524/41 |
Current CPC
Class: |
C08L 1/10 20130101; C08L
1/10 20130101; C08K 13/08 20130101; C08J 3/20 20130101; C08L 1/14
20130101; C08L 21/00 20130101; C08L 1/12 20130101 |
Class at
Publication: |
524/41 |
International
Class: |
C08L 1/12 20060101
C08L001/12 |
Claims
1. An elastomeric composition comprising at least one primary
elastomer, one or more fillers, and at least one non-fibril
cellulose ester, wherein said elastomeric composition exhibits a
dynamic mechanical analysis (DMA) strain sweep modulus as measured
at 5% strain and 30.degree. C. of at least 1,450,000 Pa and a
molded groove tear as measured according to ASTM D624 of at least
125 lbf/in.
2. The elastomeric composition according to claim 1 wherein said
elastomeric composition exhibits a Mooney viscosity at 100.degree.
C. as measured according to ASTM D 1646 of not more than 110 AU
when said elastomeric composition is uncured.
3. The elastomeric composition according to claim 1 wherein said
elastomeric composition exhibits a DMA strain sweep modulus as
measured at 5% strain and 30.degree. C. of at least 1,600,000
Pa.
4. The elastomeric composition according to claim 1 wherein said
elastomeric composition exhibits a molded groove tear as measured
according to ASTM D624 of at least 130 lbf/in.
5. The elastomeric composition according to claim 1 wherein said
elastomeric compositions comprises at least 1 and/or not more than
75 phr of said cellulose ester.
6. The elastomeric composition according to claim 1 wherein said
elastomeric composition comprises at least 75 phr and/or not more
than 150 phr of said one or more fillers.
7. The elastomeric composition according to claim 1 wherein said
cellulose ester is selected from the group consisting of cellulose
acetate, cellulose acetate propionate, cellulose acetate butyrate
cellulose triacetate, cellulose tripropionate, cellulose
tributyrate, and mixtures thereof.
8. The elastomeric composition according to claim 1 wherein at
least 75 percent of said particles have an aspect ratio of not more
than 2:1.
9. The elastomeric composition according to claim 1 wherein at
least 75 percent of said particles have a particle size of not more
than 10 .mu.m.
10. The elastomeric composition according to claim 1 wherein said
fillers comprise silica, carbon black, clay, alumina, talc, mica,
discontinuous fibers including cellulose fibers and glass fibers,
aluminum silicate, aluminum trihydrate, barites, feldspar,
nepheline, antimony oxide, calcium carbonate, kaolin, and
combinations thereof.
11. The elastomeric composition according to claim 1 wherein said
primary elastomer is non-polar.
12. The elastomeric composition according to claim 1 wherein said
primary elastomer comprises a non-nitrile elastomer.
13. The elastomeric composition according to claim 1 wherein said
primary elastomer is selected from the group consisting of natural
rubber, polybutadiene, polyisoprene, styrene-butadiene rubber,
polyolefins, ethylene propylene diene monomer (EPDM),
polynorbornene, and combinations thereof.
14. The elastomeric composition according to claim 1 wherein said
elastomeric composition further comprises a non-cellulose ester
processing aid.
15. The elastomeric composition according to claim 1 wherein said
elastomeric composition comprises less than 3 phr of a starch.
16. The elastomeric composition according to claim 1 wherein said
cellulose ester is a modified cellulose ester that has been
modified by at least one plasticizer.
17. The elastomeric composition according to claim 1 wherein said
plasticizer forms at least 1 and/or not more than 60 weight percent
of said modified cellulose ester.
18. The elastomeric composition according to claim 1 wherein said
plasticizer is one selected from the group consisting of a
phosphate plasticizer, benzoate plasticizer, adipate plasticizer, a
phthalate plasticizer, a glycolic acid ester, a citric acid ester
plasticizer, and a hydroxyl-functional plasticizer.
19. An article comprising said elastomeric composition of claim
1.
20. The article according to claim 19 wherein said article
comprises a tire.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. Nos. 61/567,948, 61/567,950, 61/567,951, and
61/567,953 filed on Dec. 7th, 2011, the disclosures of which are
incorporated herein by reference to the extent they do not
contradict the statements herein.
FIELD OF THE INVENTION
[0002] The present invention relates generally to elastomeric
compositions comprising a cellulose ester and to processes for
making such elastomeric compositions.
BACKGROUND OF THE INVENTION
[0003] Elastomeric compositions comprising high amounts of filler
are utilized in various applications, such as in tires, where
increased elasticity, hardness, tear resistance, and stiffness are
desired. These enhanced properties are generally achieved by adding
large amounts of hard fillers (e.g., carbon black, silica, and
other minerals) to the elastomeric composition. An additional
benefit of highly-filled compositions is that they can be produced
on a more economic scale compared to elastomeric compositions
containing little or no fillers. The elastomer components are
generally the most expensive component in an elastomeric
composition, thus the utilization of high amounts of filler can
minimize the amount of expensive elastomer used in the elastomeric
composition.
[0004] Unfortunately, the presence of high amounts of fillers in an
elastomeric composition greatly increases the processing viscosity
of the composition, thus making it very difficult to process. One
current solution to this problem is to add a processing aid, such
as an aromatic processing oil, to the elastomeric composition in
order to reduce its processing viscosity. However, the
incorporation of processing aids into the elastomeric compositions
generally softens the cured elastomeric compositions, thereby
mitigating the desired benefits of adding high amounts of filler to
the composition.
[0005] Accordingly, there is a need for a highly-filled elastomeric
composition that is both easily processable and that exhibits ideal
elasticity, hardness, tear resistance, and stiffness when cured. In
addition, there is a need for a processing aid for elastomeric
compositions that can improve the processability of the elastomeric
composition and also enhance its elasticity, hardness, tear
resistance, and/or stiffness.
BRIEF SUMMARY OF THE INVENTION
[0006] In one embodiment of the present invention, an elastomeric
composition is provided that comprises at least one non-fibril
cellulose ester, at least one non-nitrile primary elastomer,
optionally a starch, and at least about 70 parts per hundred rubber
(phr) of one or more fillers. The ratio of cellulose ester to
starch in the composition is at least about 3:1. Further, the
cellulose ester is in the form of particles having an average
diameter of less than about 10 .mu.m.
[0007] In another embodiment of the present invention, an
elastomeric composition is provided comprising at least one primary
elastomer, one or more fillers, and at least one non-fibril
cellulose ester. The elastomeric composition exhibits a dynamic
mechanical analysis (DMA) strain sweep modulus as measured at 5%
strain and 30.degree. C. of at least 1,450,000 Pa and a molded
groove tear as measured according to ASTM D624 of at least about
125 lbf/in.
[0008] In yet another embodiment of the present invention, a
process for producing an elastomeric composition is provided. The
process comprises blending at least one cellulose ester, at least
one non-nitrile primary elastomer, and at least 70 phr of one or
more fillers at a temperature that exceeds the Tg of the cellulose
ester to produce an elastomeric composition. The newly-produced
elastomeric composition exhibits a Mooney viscosity at 100.degree.
C. as measured according to ASTM D1646 of not more than about 110
AU.
[0009] In a further embodiment of the present invention, a process
to produce an elastomeric composition is provided. The process
comprises blending at least one cellulose ester, at least one
primary elastomer, and one or more fillers at a temperature that
exceeds the Tg of the cellulose ester to produce an uncured
elastomeric composition; and curing the uncured elastomeric
composition to produce a cured elastomeric composition. The uncured
elastomeric composition exhibits a Mooney viscosity as measured
according to ASTM D1646 of not more than about 110 AU. Furthermore,
the cured elastomeric composition exhibits a dynamic mechanical
analysis (DMA) strain sweep modulus as measured at 5% strain and
30.degree. C. of at least 1,450,000 Pa and a molded groove tear as
measured according to ASTM D624 of at least about 120 lbf/in.
[0010] Other inventions concerning the use of cellulose esters in
elastomers have been filed in original applications by Eastman
Chemical Company on November 30.sup.th, 2012 entitled "Cellulose
Esters in Pneumatic Tires", "Cellulose Ester Elastomer
Compositions", and "Process for Dispersing Cellulose Esters into
Elastomeric Compositions; the disclosures of which are hereby
incorporated by reference to the extent that they do not contradict
the statements herein.
DETAILED DESCRIPTION
[0011] This invention relates generally to the dispersion of
cellulose esters into elastomeric compositions in order to improve
the mechanical and physical properties of the elastomeric
composition. It has been observed that cellulose esters can provide
a dual functionality when utilized in elastomeric compositions and
their production. For instance, cellulose esters can act as a
processing aid since they can melt and flow at elastomer processing
temperatures, thereby breaking down into smaller particles and
reducing the viscosity of the composition during processing. After
being dispersed throughout the elastomeric composition, the
cellulose esters can re-solidify upon cooling and can act as a
reinforcing filler that strengthens the composition.
[0012] In certain embodiments of this invention, a highly-filled
elastomeric composition is provided that comprises high amounts of
one or more fillers. Highly-filled elastomeric compositions are
desirable for various applications where modulus, strength, and
elasticity are necessary. Unfortunately, it has been observed that
adding high amounts of filler to an elastomeric composition makes
subsequent processing of the elastomeric composition very difficult
due to the increased viscosity of the composition. However, the
addition of cellulose esters to the elastomeric composition can
remedy many of the deficiencies exhibited by conventional
highly-filled elastomeric compositions. Thus, in certain
embodiments of the present invention, cellulose esters can enable
the production of highly-filled elastomeric compositions exhibiting
superior viscosity during processing and enhanced modulus,
stiffness, hardness, and tear properties during use.
[0013] In certain embodiments of this invention, an elastomeric
composition is provided that comprises at least one cellulose
ester, at least one primary elastomer, optionally, one or more
fillers, and, optionally, one or more additives.
(A) Cellulose Esters
[0014] The elastomeric composition of the present invention can
comprise at least about 1, 2, 3, 4, 5, or 10 parts per hundred
rubber ("phr") of at least one cellulose ester, based on the total
weight of the elastomers. Additionally or alternatively, the
elastomeric composition of the present invention can comprise not
more than about 75, 50, 40, 30, or 20 phr of at least one cellulose
ester, based on the total weight of the elastomers. The term "phr,"
as used herein, refers to parts of a respective material per 100
parts by weight of rubber or elastomer.
[0015] The cellulose ester utilized in this invention can be any
that is known in the art. The cellulose esters useful in the
present invention can be prepared using techniques known in the art
or can be commercially obtained, e.g., from Eastman Chemical
Company, Kingsport, Tenn., U.S.A.
[0016] The cellulose esters of the present invention generally
comprise repeating units of the structure:
##STR00001##
wherein R.sup.1, R.sup.2, and R.sup.3 may be selected independently
from the group consisting of hydrogen or a straight chain alkanoyl
having from 2 to 10 carbon atoms. For cellulose esters, the
substitution level is usually expressed in terms of degree of
substitution ("DS"), which is the average number of substitutents
per anhydroglucose unit ("AGU"). Generally, conventional cellulose
contains three hydroxyl groups per AGU that can be substituted;
therefore, the DS can have a value between zero and three.
Alternatively, lower molecular weight cellulose mixed esters can
have a total degree of substitution ranging from about 3.08 to
about 3.5. Generally, cellulose is a large polysaccharide with a
degree of polymerization from 700 to 2,000 and a maximum DS of 3.0.
However, as the degree of polymerization is lowered, as in low
molecular weight cellulose mixed esters, the end groups of the
polysaccharide backbone become relatively more significant, thereby
resulting in a DS ranging from about 3.08 to about 3.5.
[0017] Because DS is a statistical mean value, a value of 1 does
not assure that every AGU has a single substituent. In some cases,
there can be unsubstituted AGUs, some with two substitutents, and
some with three substitutents. The "total DS" is defined as the
average number of substitutents per AGU. In one embodiment of the
invention, the cellulose esters can have a total DS per AGU
(DS/AGU) of at least about 0.5, 0.8, 1.2, 1.5, or 1.7. Additionally
or alternatively, the cellulose esters can have a total DS/AGU of
not more than about 3.0, 2.9, 2.8, or 2.7. The DS/AGU can also
refer to a particular substituent, such as, for example, hydroxyl,
acetyl, butyryl, or propionyl. For instance, a cellulose acetate
can have a total DS/AGU for acetyl of about 2.0 to about 2.5, while
a cellulose acetate propionate ("CAP") and cellulose acetate
butyrate ("CAB") can have a total DS/AGU of about 1.7 to about
2.8.
[0018] The cellulose ester can be a cellulose triester or a
secondary cellulose ester. Examples of cellulose triesters include,
but are not limited to, cellulose triacetate, cellulose
tripropionate, or cellulose tributyrate. Examples of secondary
cellulose esters include cellulose acetate, cellulose acetate
propionate, and cellulose acetate butyrate. These cellulose esters
are described in U.S. Pat. Nos. 1,698,049; 1,683,347; 1,880,808;
1,880,560; 1,984,147, 2,129,052; and 3,617,201, which are
incorporated herein by reference in their entirety to the extent
they do not contradict the statements herein.
[0019] In one embodiment of the invention, the cellulose ester is
selected from the group consisting of cellulose acetate, cellulose
acetate propionate, cellulose acetate butyrate, cellulose
triacetate, cellulose tripropionate, cellulose tributyrate, and
mixtures thereof.
[0020] The degree of polymerization ("DP") as used herein refers to
the number of AGUs per molecule of cellulose ester. In one
embodiment of the invention, the cellulose esters can have a DP of
at least about 2, 10, 50, or 100. Additionally or alternatively,
the cellulose esters can have a DP of not more than about 10,000,
8,000, 6,000, or 5,000.
[0021] In certain embodiments, the cellulose esters can have an
inherent viscosity ("IV") of at least about 0.2, 0.4, 0.6, 0.8, or
1.0 deciliters/gram as measured at a temperature of 25.degree. C.
for a 0.25 gram sample in 100 ml of a 60/40 by weight solution of
phenol/tetrachloroethane. Additionally or alternatively, the
cellulose esters can have an IV of not more than about 3.0, 2.5,
2.0, or 1.5 deciliters/gram as measured at a temperature of
25.degree. C. for a 0.25 gram sample in 100 ml of a 60/40 by weight
solution of phenol/tetrachloroethane.
[0022] In certain embodiments, the cellulose esters can have a
falling ball viscosity of at least about 0.005, 0.01, 0.05, 0.1,
0.5, 1, or 5 pascals-second ("Pa s"). Additionally or
alternatively, the cellulose esters can have a falling ball
viscosity of not more than about 50, 45, 40, 35, 30, 25, 20, or 10
Pas.
[0023] In certain embodiments, the cellulose esters can have a
hydroxyl content of at least about 1.2, 1.4, 1.6, 1.8, or 2.0
weight percent.
[0024] In certain embodiments, the cellulose esters useful in the
present invention can have a weight average molecular weight
(M.sub.w) of at least about 5,000, 10,000, 15,000, or 20,000 as
measured by gel permeation chromatography ("GPC"). Additionally or
alternatively, the cellulose esters useful in the present invention
can have a weight average molecular weight (M.sub.w) of not more
than about 400,000, 300,000, 250,000, 100,000, or 80,000 as
measured by GPC. In another embodiment, the cellulose esters useful
in the present invention can have a number average molecular weight
(M.sub.n) of at least about 2,000, 4,000, 6,000, or 8,000 as
measured by GPC. Additionally or alternatively, the cellulose
esters useful in the present invention can have a number average
molecular weight (M.sub.n) of not more than about 100,000, 80,000,
60,000, or 40,000 as measured by GPC.
[0025] In certain embodiments, the cellulose esters can have a
glass transition temperature ("Tg") of at least about 50.degree.
C., 55.degree. C., 60.degree. C., 65.degree. C., 70.degree. C.,
75.degree. C., or 80.degree. C. Additionally or alternatively, the
cellulose esters can have a Tg of not more than about 200.degree.
C., 190.degree. C., 180.degree. C., 170.degree. C., 160.degree. C.,
150.degree. C., 140.degree. C., or 130.degree. C.
[0026] In one embodiment of the present invention, the cellulose
esters utilized in the elastomeric compositions have not previously
been subjected to fibrillation or any other fiber-producing
process. In such an embodiment, the cellulose esters are not in the
form of fibrils and can be referred to as "non-fibril."
[0027] The cellulose esters can be produced by any method known in
the art. Examples of processes for producing cellulose esters are
taught in Kirk-Othmer, Encyclopedia of Chemical Technology, 5th
Edition, Vol. 5, Wiley-Interscience, New York (2004), pp. 394-444.
Cellulose, the starting material for producing cellulose esters,
can be obtained in different grades and from sources such as, for
example, cotton linters, softwood pulp, hardwood pulp, corn fiber
and other agricultural sources, and bacterial celluloses.
[0028] One method of producing cellulose esters is by
esterification. In such a method, the cellulose is mixed with the
appropriate organic acids, acid anhydrides, and catalysts and then
converted to a cellulose triester. Ester hydrolysis is then
performed by adding a water-acid mixture to the cellulose triester,
which can be filtered to remove any gel particles or fibers. Water
is added to the mixture to precipitate out the cellulose ester. The
cellulose ester can be washed with water to remove reaction
by-products followed by dewatering and drying.
[0029] The cellulose triesters that are hydrolyzed can have three
substitutents selected independently from alkanoyls having from 2
to 10 carbon atoms. Examples of cellulose triesters include
cellulose triacetate, cellulose tripropionate, and cellulose
tributyrate or mixed triesters of cellulose such as cellulose
acetate propionate and cellulose acetate butyrate. These cellulose
triesters can be prepared by a number of methods known to those
skilled in the art. For example, cellulose triesters can be
prepared by heterogeneous acylation of cellulose in a mixture of
carboxylic acid and anhydride in the presence of a catalyst such as
H.sub.2SO.sub.4. Cellulose triesters can also be prepared by the
homogeneous acylation of cellulose dissolved in an appropriate
solvent such as LiCl/DMAc or LiCl/NMP.
[0030] Those skilled in the art will understand that the commercial
term of cellulose triesters also encompasses cellulose esters that
are not completely substituted with acyl groups. For example,
cellulose triacetate commercially available from Eastman Chemical
Company, Inc., Kingsport, Tenn., U.S.A., typically has a DS from
about 2.85 to about 2.95.
[0031] After esterification of the cellulose to the triester, part
of the acyl substitutents can be removed by hydrolysis or by
alcoholysis to give a secondary cellulose ester. Secondary
cellulose esters can also be prepared directly with no hydrolysis
by using a limiting amount of acylating reagent. This process is
particularly useful when the reaction is conducted in a solvent
that will dissolve cellulose.
[0032] In another embodiment of the invention, low molecular weight
mixed cellulose esters can be utilized, such as those disclosed in
U.S. Pat. No. 7,585,905, which is incorporated herein by reference
to the extent it does not contradict the statements herein.
[0033] In one embodiment of the invention, a low molecular weight
mixed cellulose ester is utilized that has the following
properties: (A) a total DS/AGU of from about 3.08 to about 3.50
with the following substitutions: a DS/AGU of hydroxyl of not more
than about 0.70, a DS/AGU of C3/C4 esters from about 0.80 to about
1.40, and a DS/AGU of acetyl of from about 1.20 to about 2.34; an
IV of from about 0.05 to about 0.15 dL/g, as measured in a 60/40
(wt./wt.) solution of phenol/tetrachloroethane at 25.degree. C.; a
number average molecular weight of from about 1,000 to about 5,600;
a weight average molecular weight of from about 1,500 to about
10,000; and a polydispersity of from about 1.2 to about 3.5.
[0034] In another embodiment of the invention, a low molecular
weight mixed cellulose ester is utilized that has the following
properties: a total DS/AGU of from about 3.08 to about 3.50 with
the following substitutions: a DS/AGU of hydroxyl of not more than
about 0.70; a DS/AGU of C3/C4 esters from about 1.40 to about 2.45,
and DS/AGU of acetyl of from about 0.20 to about 0.80; an IV of
from about 0.05 to about 0.15 dL/g, as measured in a 60/40
(wt./wt.) solution of phenol/tetrachloroethane at 25.degree. C.; a
number average molecular weight of from about 1,000 to about 5,600;
a weight average molecular weight of from about 1,500 to about
10,000; and a polydispersity of from about 1.2 to about 3.5.
[0035] In yet another embodiment of the invention, a low molecular
weight mixed cellulose ester is utilized that has the following
properties: a total DS/AGU of from about 3.08 to about 3.50with the
following substitutions: a DS/AGU of hydroxyl of not more than
about 0.70; a DS/AGU of C3/C4 esters from about 2.11 to about 2.91,
and a DS/AGU of acetyl of from about 0.10 to about 0.50; an IV of
from about 0.05 to about 0.15 dL/g, as measured in a 60/40
(wt./wt.) solution of phenol/tetrachloroethane at 25.degree. C.; a
number average molecular weight of from about 1,000 to about 5,600;
a weight average molecular weight of from about 1,500 to about
10,000; and a polydispersity of from about 1.2 to about 3.5.
[0036] In certain embodiments, the cellulose esters utilized in
this invention can also contain chemical functionality. In such
embodiments, the cellulose esters are described herein as
"derivatized," "modified," or "functionalized" cellulose
esters.
[0037] Functionalized cellulose esters are produced by reacting the
free hydroxyl groups of cellulose esters with a bifunctional
reactant that has one linking group for grafting to the cellulose
ester and one functional group to provide a new chemical group to
the cellulose ester. Examples of such bifunctional reactants
include succinic anhydride, which links through an ester bond and
provides acid functionality; mercaptosilanes, which links through
alkoxysilane bonds and provides mercapto functionality; and
isocyanotoethyl methacrylate, which links through a urethane bond
and gives methacrylate functionality.
[0038] In one embodiment of the invention, the functionalized
cellulose esters comprise at least one functional group selected
from the group consisting of unsaturation (double bonds),
carboxylic acids, acetoacetate, acetoacetate imide, mercapto,
melamine, and long alkyl chains.
[0039] Bifunctional reactants to produce cellulose esters
containing unsaturation (double bonds) functionality are described
in U.S. Pat. Nos. 4,839,230, 5,741,901, 5,871,573, 5,981,738,
4,147,603, 4,758,645, and 4,861,629; all of which are incorporated
by reference to the extent they do not contradict the statements
herein. In one embodiment, the cellulose esters containing
unsaturation are produced by reacting a cellulose ester containing
residual hydroxyl groups with an acrylic-based compound and
m-isopropyenyl-.alpha.,.alpha.'-dimethylbenzyl isocyanate. The
grafted cellulose ester is a urethane-containing product having
pendant (meth)acrylate and .alpha.-methylstyrene moieties. In
another embodiment, the cellulose esters containing unsaturation
are produced by reacting maleic anhydride and a cellulose ester in
the presence of an alkaline earth metal or ammonium salt of a lower
alkyl monocarboxylic acid catalyst, and at least one saturated
monocarboxylic acid have 2 to 4 carbon atoms. In another
embodiment, the cellulose esters containing unsaturation are
produced from the reaction product of (a) at least one cellulosic
polymer having isocyanate reactive hydroxyl functionality and (b)
at least one hydroxyl reactive poly(.alpha.,.beta.ethyleneically
unsaturated) isocyanate.
[0040] Bifunctional reactants to produce cellulose esters
containing carboxylic acid functionality are described in U.S. Pat.
Nos. 5,384,163, 5,723,151, and 4,758,645; all of which are
incorporated by reference to the extent they do not contradict the
statements herein. In one embodiment, the cellulose esters
containing carboxylic acid functionality are produced by reacting a
cellulose ester and a mono- or di-ester of maleic or furmaric acid,
thereby obtaining a cellulose derivative having double bond
functionality. In another embodiment, the cellulose esters
containing carboxylic acid functionality has a first and second
residue, wherein the first residue is a residue of a cyclic
dicarboxylic acid anhydride and the second residue is a residue of
an oleophilic monocarboxylic acid and/or a residue of a hydrophilic
monocarboxylic acid. In yet another embodiment, the cellulose
esters containing carboxylic acid functionality are cellulose
acetate phthalates, which can be prepared by reacting cellulose
acetate with phthalic anhydride.
[0041] Bifunctional reactants to produce cellulose esters
containing acetoacetate functionality are described in U.S. Pat.
No. 5,292,877, which is incorporated by reference to the extent it
does not contradict the statements herein. In one embodiment, the
cellulose esters containing acetoacetate functionality are produced
by contacting: (i) cellulose; (ii) diketene, an alkyl acetoacetate,
2,2,6, trimethyl-4H 1,3-dioxin-4-one, or a mixture thereof, and
(iii) a solubilizing amount of solvent system comprising lithium
chloride plus a carboxamide selected from the group consisting of
1-methyl-2-pyrolidinone, N,N dimethylacetamide, or a mixture
thereof.
[0042] Bifunctional reactants to produce cellulose esters
containing acetoacetate imide functionality are described in U.S.
Pat. No. 6,369,214, which is incorporated by reference to the
extent it does not contradict the statements herein. Cellulose
esters containing acetoacetate imide functionality are the reaction
product of a cellulose ester and at least one acetoacetyl group and
an amine functional compound comprising at least one primary
amine.
[0043] Bifunctional reactants to produce cellulose esters
containing mercapto functionality are described in U.S. Pat. No.
5,082,914, which is incorporated by reference to the extent it does
not contradict the statements herein. In one embodiment of the
invention, the cellulose ester is grafted with a silicon-containing
thiol component which is either commercially available or can be
prepared by procedures known in the art. Examples of
silicon-containing thiol compounds include, but are not limited to,
(3-mercaptopropyl)trimethoxysilane,
(3-mercaptopropyl)-dimethyl-methoxysilane,
(3-mercaptopropyl)dimethoxymethylsilane,
(3-mercaptopropyl)dimethylchlorosilane,
(3-mercaptopropyl)dimethylethoxysilane,
(3-mercaptopropyl)diethyoxy-methylsilane, and
(3-mercapto-propyl)triethoxysilane.
[0044] Bifunctional reactants to produce cellulose esters
containing melamine functionality are described in U.S. Pat. No.
5,182,379, which is incorporated by reference to the extent it does
not contradict the statements herein. In one embodiment, the
cellulose esters containing melamine functionality are prepared by
reacting a cellulose ester with a melamine compound to form a
grafted cellulose ester having melamine moieties grafted to the
backbone of the anhydrogluclose rings of the cellulose ester. In
one embodiment, the melamine compound is selected from the group
consisting of methylol ethers of melamine and aminoplast carrier
elastomers.
[0045] Bifunctional reactants to produce cellulose esters
containing long alkyl chain functionality are described in U.S.
Pat. No. 5,750,677, which is incorporated by reference to the
extent it does not contradict the statements herein. In one
embodiment, the cellulose esters containing long alkyl chain
functionality are produced by reacting cellulose in carboxamide
diluents or urea-based diluents with an acylating reagent using a
titanium-containing species. Cellulose esters containing long alkyl
chain functionality can be selected from the group consisting of
cellulose acetate hexanoate, cellulose acetate nonanoate, cellulose
acetate laurate, cellulose palmitate, cellulose acetate stearate,
cellulose nonanoate, cellulose hexanoate, cellulose hexanoate
propionate, and cellulose nonanoate propionate.
[0046] In certain embodiments of the invention, the cellulose ester
can be modified using one or more plasticizers. The plasticizer can
form at least about 1, 2, 5, or 10 weight percent of the cellulose
ester composition. Additionally or alternatively, the plasticizer
can make up not more than about 60, 50, 40, or 35 weight percent of
the cellulose ester composition. In one embodiment, the cellulose
ester is a modified cellulose ester that was formed by modifying an
initial cellulose ester with a plasticizer.
[0047] The plasticizer used for modification can be any that is
known in the art that can reduce the melt temperature and/or the
melt viscosity of the cellulose ester. The plasticizer can be
either monomeric or polymeric in structure. In one embodiment, the
plasticizer is at least one selected from the group consisting of a
phosphate plasticizer, benzoate plasticizer, adipate plasticizer, a
phthalate plasticizer, a glycolic acid ester, a citric acid ester
plasticizer, and a hydroxyl-functional plasticizer.
[0048] In one embodiment of the invention, the plasticizer can be
selected from at least one of the following: triphenyl phosphate,
tricresyl phosphate, cresyldiphenyl phosphate, octyldiphenyl
phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl
phosphate, diethyl phthalate, dimethoxyethyl phthalate, dimethyl
phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl
phthalate, butylbenzyl phthalate, dibenzyl phthalate, butyl
phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl
phthalyl ethyl glycolate, triethyl citrate, tri-n-butyl citrate,
acetyltriethyl citrate, acetyl-tri-n-butyl citrate, and acetyl-
tri-n-(2-ethylhexyl) citrate.
[0049] In another embodiment of the invention, the plasticizer can
be one or more esters comprising (i) at least one acid residue
including residues of phthalic acid, adipic acid, trimellitic acid,
succinic acid, benzoic acid, azelaic acid, terephthalic acid,
isophthalic acid, butyric acid, glutaric acid, citric acid, and/or
phosphoric acid; and (ii) alcohol residues comprising one or more
residues of an aliphatic, cycloaliphatic, or aromatic alcohol
containing up to about 20 carbon atoms.
[0050] In another embodiment of the invention, the plasticizer can
comprise alcohol residues containing residues selected from the
following: stearyl alcohol, lauryl alcohol, phenol, benzyl alcohol,
hydroquinone, catechol, resorcinol, ethylene glycol, neopentyl
glycol, 1,4-cyclohexanedimethanol, and diethylene glycol.
[0051] In another embodiment of the invention, the plasticizer can
be selected from at least one of the following: benzoates,
phthalates, phosphates, arylene-bis(diaryl phosphate), and
isophthalates. In another embodiment, the plasticizer comprises
diethylene glycol dibenzoate, abbreviated herein as "DEGDB".
[0052] In another embodiment of the invention, the plasticizer can
comprise aliphatic polyesters containing C2-10 diacid residues such
as, for example, malonic acid, succinic acid, glutaric acid, adipic
acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid;
and C2-10 diol residues.
[0053] In another embodiment, the plasticizer can comprise diol
residues which can be residues of at least one of the following
C2-C10 diols ethylene glycol, diethylene glycol, 1,2-propylene
glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene
glycol, 1,4-butylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6
hexanediol, 1,5-pentylene glycol, triethylene glycol, and
tetraethylene glycol.
[0054] In another embodiment of the invention, the plasticizer can
include polyglycols, such as, for example, polyethylene glycol,
polypropylene glycol, and polybutylene glycol. These can range from
low molecular weight dimers and trimers to high molecular weight
oligomers and polymers. In one embodiment, the molecular weight of
the polyglycol can range from about 200 to about 2,000.
[0055] In another embodiment of the invention, the plasticizer
comprises at least one of the following: Resoflex.RTM. R296
plasticizer, Resoflex.RTM. 804 plasticizer, SHP (sorbitol
hexapropionate), XPP (xylitol pentapropionate), XPA (xylitol
pentaacetate), GPP (glucose pentaacetate), GPA (glucose
pentapropionate), and APP (arabitol pentapropionate).
[0056] In another embodiment of the invention, the plasticizer
comprises one or more of: A) from about 5 to about 95 weight
percent of a C2-C12 carbohydrate organic ester, wherein the
carbohydrate comprises from about 1 to about 3 monosaccharide
units; and B) from about 5 to about 95 weight percent of a C2-C12
polyol ester, wherein the polyol is derived from a C5 or C6
carbohydrate. In one embodiment, the polyol ester does not comprise
or contain a polyol acetate or polyol acetates.
[0057] In another embodiment, the plasticizer comprises at least
one carbohydrate ester and the carbohydrate portion of the
carbohydrate ester is derived from one or more compounds selected
from the group consisting of glucose, galactose, mannose, xylose,
arabinose, lactose, fructose, sorbose, sucrose, cellobiose,
cellotriose, and raffinose.
[0058] In another embodiment of the invention, the plasticizer
comprises at least one carbohydrate ester and the carbohydrate
portion of the carbohydrate ester comprises one or more of
.alpha.-glucose pentaacetate, .beta.-glucose pentaacetate,
.alpha.-glucose pentapropionate, .beta.-glucose pentapropionate,
.alpha.-glucose pentabutyrate, and .beta.-glucose
pentabutyrate.
[0059] In another embodiment, the plasticizer comprises at least
one carbohydrate ester and the carbohydrate portion of the
carbohydrate ester comprises an .alpha.-anomer, a .beta.-anomer, or
a mixture thereof.
[0060] In another embodiment of the invention, the plasticizer can
be a solid, non-crystalline carrier elastomer. These carrier
elastomers can contain some amount of aromatic or polar
functionality and can lower the melt viscosity of the cellulose
esters. In one embodiment of the invention, the plasticizer can be
a solid, non-crystalline compound, such as, for example, a rosin; a
hydrogenated rosin; a stabilized rosin, and their monofunctional
alcohol esters or polyol esters; a modified rosin including, but
not limited to, maleic- and phenol-modified rosins and their
esters; terpene elastomers; phenol-modified terpene elastomers;
coumarin-indene elastomers; phenolic elastomers;
alkylphenol-acetylene elastomers; and phenol-formaldehyde
elastomers.
[0061] In another embodiment of the invention, the plasticizer can
be a tackifier resin. Any tackifier known to a person of ordinary
skill in the art may be used in the elastomeric compositions.
Tackifiers suitable for the compositions disclosed herein can be
solids, semi-solids, or liquids at room temperature. Non-limiting
examples of tackifiers include (1) natural and modified rosins
(e.g., gum rosin, wood rosin, tall oil rosin, distilled rosin,
hydrogenated rosin, dimerized rosin, and polymerized rosin); (2)
glycerol and pentaerythritol esters of natural and modified rosins
(e.g., the glycerol ester of pale, wood rosin, the glycerol ester
of hydrogenated rosin, the glycerol ester of polymerized rosin, the
pentaerythritol ester of hydrogenated rosin, and the
phenolic-modified pentaerythritol ester of rosin); (3) copolymers
and terpolymers of natured terpenes (e.g., styrene/terpene and
alpha methyl styrene/terpene); (4) polyterpene resins and
hydrogenated polyterpene resins; (5) phenolic modified terpene
resins and hydrogenated derivatives thereof (e.g., the resin
product resulting from the condensation, in an acidic medium, of a
bicyclic terpene and a phenol); (6) aliphatic or cycloaliphatic
hydrocarbon resins and the hydrogenated derivatives thereof (e.g.,
resins resulting from the polymerization of monomers consisting
primarily of olefins and diolefins); (7) aromatic hydrocarbon
resins and the hydrogenated derivatives thereof; and (8) aromatic
modified aliphatic or cycloaliphatic hydrocarbon resins and the
hydrogenated derivatives thereof; and combinations thereof.
[0062] In another embodiment of the invention, the tackifier resins
include rosin-based tackifiers (e.g. AQUATAC.RTM. 9027,
AQUATAC.RTM. 4188, SYLVALITE.RTM., SYLVATAC.RTM. and SYL V
AGUM.RTM. rosin esters from Arizona Chemical, Jacksonville, Fla.).
In other embodiments, the tackifiers include polyterpenes or
terpene resins (e.g., SYLVARES.RTM. 15 terpene resins from Arizona
Chemical, Jacksonville, Fla.). In other embodiments, the tackifiers
include aliphatic hydrocarbon resins such as resins resulting from
the polymerization of monomers consisting of olefins and diolefins
(e.g., ESCOREZ.RTM. 1310LC,ESCOREZ.RTM. 2596 from ExxonMobil
Chemical Company, Houston, Tex. or PICCOTAC.RTM. 1095 from Eastman
Chemical Company, Kingsport, Tenn.) and the hydrogenated
derivatives 20 thereof; alicyclic petroleum hydrocarbon resins and
the hydrogenated derivatives thereof (e.g. ESCOREZ.RTM. 5300 and
5400 series from ExxonMobil Chemical Company; EASTOTAC.RTM. resins
from Eastman Chemical Company). In some embodiments, the tackifiers
include hydrogenated cyclic hydrocarbon resins (e. g. REGALREZ.RTM.
and REGALITE.RTM. resins from Eastman Chemical Company). In further
embodiments, the tackifiers are modified with tackifier modifiers
including aromatic compounds (e.g., ESCOREZ.RTM. 2596 from
ExxonMobil Chemical Company or PICCOTAC.RTM. 7590 from Eastman
Chemical Company) and low softening point resins (e.g., AQUATAC
5527 from Arizona Chemical, Jacksonville, Fla.). In some
embodiments, the tackifier is an aliphatic hydrocarbon resin having
at least five carbon atoms.
[0063] In certain embodiments of the present invention, the
cellulose ester can be modified using one or more compatibilizers.
The compatibilizer can comprise at least about 1, 2, 3, or 5 weight
percent of the cellulose ester composition. Additionally or
alternatively, the compatibilizer can comprise not more than about
40, 30, 25, or 20 weight percent of the cellulose ester
composition.
[0064] The compatibilizer can be either a non-reactive
compatibilizer or a reactive compatibilizer. The compatibilizer can
enhance the ability of the cellulose ester to reach a desired small
particle size thereby improving the dispersion of the cellulose
ester into an elastomer. The compatibilizers used can also improve
mechanical and physical properties of the elastomeric compositions
by enhancing the interfacial interaction/bonding between the
cellulose ester and the elastomer.
[0065] When non-reactive compatibilizers are utilized, the
compatibilizer can contain a first segment that is compatible with
the cellulose ester and a second segment that is compatible with
the elastomer. In this case, the first segment contains polar
functional groups, which provide compatibility with the cellulose
ester, including, but not limited to, such polar functional groups
as ethers, esters, amides, alcohols, amines, ketones, and acetals.
The first segment may include oligomers or polymers of the
following: cellulose esters; cellulose ethers; polyoxyalkylene,
such as, polyoxyethylene, polyoxypropylene, and polyoxybutylene;
polyglycols, such as, polyethylene glycol, polypropylene glycol,
and polybutylene glycol; polyesters, such as, polycaprolactone,
polylactic acid, aliphatic polyesters, and aliphatic-aromatic
copolyesters; polyacrylates and polymethacrylates; polyacetals;
polyvinylpyrrolidone; polyvinyl acetate; and polyvinyl alcohol. In
one embodiment, the first segment is polyoxyethylene or polyvinyl
alcohol.
[0066] The second segment can be compatible with the elastomer and
contain nonpolar groups. The second segment can contain saturated
and/or unsaturated hydrocarbon groups. In one embodiment, the
second segment can be an oligomer or a polymer. In another
embodiment, the second segment of the non-reactive compatibilizer
is selected from the group consisting of polyolefins, polydienes,
polyaromatics, and copolymers.
[0067] In one embodiment, the first and second segments of the
non-reactive compatibilizers can be in a diblock, triblock,
branched, or comb structure. In this embodiment, the molecular
weight of the non-reactive compatibilizers can range from about 300
to about 20,000, 500 to about 10,000, or 1,000 to about 5,000. The
segment ratio of the non-reactive compatibilizers can range from
about 15 to about 85 percent polar first segments to about 15 to
about 85 percent nonpolar second segments.
[0068] Examples of non-reactive compatibilizers include, but are
not limited to, ethoxylated alcohols, ethoxylated alkylphenols,
ethoxylated fatty acids, block polymers of propylene oxide and
ethylene oxide, polyglycerol esters, polysaccharide esters, and
sorbitan esters. Examples of ethoxylated alcohols are C11-C15
secondary alcohol ethoxylates, polyoxyethylene cetyl ether,
polyoxyethylene stearyl ether, and C12-C14 natural liner alcohol
ethoxylated with ethylene oxide. C11-C15 secondary ethyoxylates can
be obtained as Dow Tergitol.RTM. 15S from the Dow Chemical Company.
Polyoxyethlene cetyl ether and polyoxyethylene stearyl ether can be
obtained from ICI Surfactants under the Brij.RTM. series of
products. C12-C14 natural linear alcohol ethoxylated with ethylene
oxide can be obtained from Hoechst Celanese under the Genapol.RTM.
series of products. Examples of ethoxylated alkylphenols include
octylphenoxy poly(ethyleneoxy)ethanol and nonylphenoxy
poly(ethyleneoxy)ethanol. Octylphenoxy poly(ethyleneoxy)ethanol can
be obtained as Igepal.RTM. CA series of products from Rhodia, and
nonylphenoxy poly(ethyleneoxy)ethanol can be obtained as Igepal CO
series of products from Rhodia or as Tergitol.RTM. NP from Dow
Chemical Company. Ethyoxylated fatty acids include
polyethyleneglycol monostearate or monolaruate which can be
obtained from Henkel under the Nopalcol.RTM. series of products.
Block polymers of propylene oxide and ethylene oxide can be
obtained under the Pluronic.RTM. series of products from BASF.
Polyglycerol esters can be obtained from Stepan under the
Drewpol.RTM. series of products. Polysaccharide esters can be
obtained from Henkel under the Glucopon.RTM. series of products,
which are alkyl polyglucosides. Sorbitan esters can be obtained
from ICI under the Tween.RTM. series of products.
[0069] In another embodiment of the invention, the non-reactive
compatibilizers can be synthesized in situ in the cellulose ester
composition or the cellulose ester/primary elastomer composition by
reacting cellulose ester-compatible compounds with
elastomer-compatible compounds. These compounds can be, for
example, telechelic oligomers, which are defined as prepolymers
capable of entering into further polymerization or other reaction
through their reactive end groups. In one embodiment of the
invention, these in situ compatibilizers can have higher molecular
weight from about 10,000 to about 1,000,000.
[0070] In another embodiment of the invention, the compatibilizer
can be reactive. The reactive compatibilizer comprises a polymer or
oligomer compatible with one component of the composition and
functionality capable of reacting with another component of the
composition. There are two types of reactive compatibilizers. The
first reactive compatibilizer has a hydrocarbon chain that is
compatible with a nonpolar elastomer and also has functionality
capable of reacting with the cellulose ester. Such functional
groups include, but are not limited to, carboxylic acids,
anhydrides, acid chlorides, epoxides, and isocyanates. Specific
examples of this type of reactive compatibilizer include, but are
not limited to: long chain fatty acids, such as stearic acid
(octadecanoic acid); long chain fatty acid chlorides, such as
stearoyl chloride (octadecanoyl chloride); long chain fatty acid
anhydrides, such as stearic anhydride (octadecanoic anhydride);
epoxidized oils and fatty esters; styrene maleic anhydride
copolymers; maleic anhydride grafted polypropylene; copolymers of
maleic anhydride with olefins and/or acrylic esters, such as
terpolymers of ethylene, acrylic ester and maleic anhydride; and
copolymers of glycidyl methacrylate with olefins and/or acrylic
esters, such as terpolymers of ethylene, acrylic ester, and
glycidyl methacrylate.
[0071] Reactive compatibilizers can be obtained as SMA.RTM. 3000
styrene maleic anhydride copolymer from Sartomer/Cray Valley,
Eastman G-3015.RTM. maleic anhydride grafted polypropylene from
Eastman Chemical Company, Epolene.RTM. E-43 maleic anhydride
grafted polypropylene obtained from Westlake Chemical, Lotader.RTM.
MAH 8200 random terpolymer of ethylene, acrylic ester, and maleic
anhydride obtained from Arkema, Lotader.RTM. GMA AX 8900 random
terpolymer of ethylene, acrylic ester, and glycidyl methacrylate,
and Lotarder.RTM. GMA AX 8840 random terpolymer of ethylene,
acrylic ester, and glycidyl methacrylate.
[0072] The second type of reactive compatibilizer has a polar chain
that is compatible with the cellulose ester and also has
functionality capable of reacting with a nonpolar elastomer.
Examples of these types of reactive compatibilizers include
cellulose esters or polyethylene glycols with olefin or thiol
functionality. Reactive polyethylene glycol compatibilizers with
olefin functionality include, but are not limited to, polyethylene
glycol allyl ether and polyethylene glycol acrylate. An example of
a reactive polyethylene glycol compatibilizer with thiol
functionality includes polyethylene glycol thiol. An example of a
reactive cellulose ester compatibilizer includes mercaptoacetate
cellulose ester.
(B) Primary Elastomers
[0073] The elastomeric composition of the present invention
comprises at least one primary elastomer. The term "elastomer," as
used herein, can be used interchangeably with the term "rubber."
Due to the wide applicability of the process described herein, the
cellulose esters can be employed with virtually any type of primary
elastomer. For instance, the primary elastomers utilized in this
invention can comprise a natural rubber, a modified natural rubber,
a synthetic rubber, and mixtures thereof.
[0074] In certain embodiments of the present invention, at least
one of the primary elastomers is a non-polar elastomer. For
example, a non-polar primary elastomer can comprise at least about
90, 95, 98, 99, or 99.9 weight percent of non-polar monomers. In
one embodiment, the non-polar primary elastomer is primarily based
on a hydrocarbon. Examples of non-polar primary elastomers include,
but are not limited to, natural rubber, polybutadiene rubber,
polyisoprene rubber, styrene-butadiene rubber, polyolefins,
ethylene propylene diene monomer (EPDM) rubber, and polynorbornene
rubber. Examples of polyolefins include, but are not limited to,
polybutylene, polyisobutylene, and ethylene propylene rubber. In
another embodiment, the primary elastomer comprises a natural
rubber, a styrene-butadiene rubber, and/or a polybutadiene
rubber.
[0075] In certain embodiments, the primary elastomer contains
little or no nitrile groups. As used herein, the primary elastomer
is considered a "non-nitrile" primary elastomer when nitrile
monomers make up less than 10 weight percent of the primary
elastomer. In one embodiment, the primary elastomer contains no
nitrile groups.
(C) Fillers
[0076] In certain embodiments, the elastomeric composition of the
present invention can comprise one or more fillers.
[0077] The fillers can comprise any filler that can improve the
thermophysical properties of the elastomeric composition (e.g.,
modulus, strength, and expansion coefficient). For example, the
fillers can comprise silica, carbon black, clay, alumina, talc,
mica, discontinuous fibers including cellulose fibers and glass
fibers, aluminum silicate, aluminum trihydrate, barites, feldspar,
nepheline, antimony oxide, calcium carbonate, kaolin, and
combinations thereof. In one embodiment, the fillers comprise an
inorganic and nonpolymeric material. In another embodiment, the
fillers comprise silica and/or carbon black. In yet another
embodiment, the fillers comprise silica.
[0078] In certain embodiments, the elastomeric composition can
comprise at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50
phr of one or more fillers, based on the total weight of the
elastomers. Additionally or alternatively, the elastomeric
composition can comprise not more than about 150, 140, 130, 120,
110, 100, 90, 80, 70, or 60 phr of one or more fillers, based on
the total weight of the elastomers.
[0079] In certain embodiments, the elastomeric composition is a
highly-filled elastomeric composition. As used herein, a
"highly-filled" elastomeric composition comprises at least about 60
phr of one or more fillers, based on the total weight of the
elastomers. In one embodiment, a highly-filled elastomeric
composition comprises at least about 65, 70, 75, 80, 85, 90, or 95
phr of one or more fillers, based on the total weight of the
elastomers. Additionally or alternatively, the highly-filled
elastomeric composition can comprise not more than about 150, 140,
130, 120, 110, or 100 phr of one or more fillers, based on the
total weight of the elastomers.
[0080] In certain embodiments, the elastomeric composition is not
highly-filled and contains minor amounts of filler. In such an
embodiment, the elastomeric composition can comprise at least about
5, 10, or 15 phr and/or not more than about 60, 50, or 40 phr of
one or more fillers, based on the total weight of the
elastomers.
(D) Optional Additives
[0081] The elastomeric composition of the present invention can
comprise one or more additives.
[0082] In certain embodiments, the elastomeric composition can
comprise at least about 1, 2, 5, 10, or 15 phr of one or more
additives, based on the total weight of the elastomers.
Additionally or alternatively, the elastomeric composition can
comprise not more than about 70, 50, 40, 30, or 20 phr of one or
more additives, based on the total weight of the elastomers.
[0083] The additives can comprise, for example, processing aids,
carrier elastomers, tackifiers, lubricants, oils, waxes,
surfactants, stabilizers, UV absorbers/inhibitors, pigments,
antioxidants, extenders, reactive coupling agents, and/or
branchers. In one embodiment, the additives comprise one or more
cellulose ethers, starches, and/or derivatives thereof. In such an
embodiment, the cellulose ethers, starches and/or derivatives
thereof can include, for example, amylose, acetoxypropyl cellulose,
amylose triacetate, amylose tributyrate, amylose tricabanilate,
amylose tripropionate, carboxymethyl amylose, ethyl cellulose,
ethyl hydroxyethyl cellulose, hydroxyethyl cellulose, methyl
cellulose, sodium carboxymethyl cellulose, and sodium cellulose
xanthanate.
[0084] In one embodiment, the additives comprise a non-cellulose
ester processing aid. The non-cellulose ester processing aid can
comprise, for example, a processing oil, starch, starch
derivatives, and/or water. In such an embodiment, the elastomeric
composition can comprise less than about 10, 5, 3, or 1 phr of the
non-cellulose ester processing aid, based on the total weight of
the elastomers. Additionally or alternatively, the elastomeric
composition can exhibit a weight ratio of cellulose ester to
non-cellulose ester processing aid of at least about 0.5:1, 1:1,
2:1, 3:1, 4:1, 5:1, 8:1, or 10:1.
[0085] In another embodiment, the elastomeric composition can
comprise a starch and/or its derivatives. In such an embodiment,
the elastomeric composition can comprise less than 10, 5, 3, or 1
phr of starch and its derivatives, based on the total weight of the
elastomers. Additionally or alternatively, the elastomeric
composition can exhibit a weight ratio of cellulose ester to starch
of at least about 3:1, 4:1, 5:1, 8:1, or 10:1.
(E) Processes for Producing Elastomeric Compositions
[0086] The elastomeric compositions of the present invention can be
produced by two different types of processes. The first process
involves directly melt dispersing the cellulose ester into a
primary elastomer. The second process involves mixing a cellulose
ester with a carrier elastomer to produce a cellulose ester
concentrate, and then blending the cellulose ester concentrate with
a primary elastomer.
[0087] In the first process, a cellulose ester is blended directly
with a primary elastomer to produce an elastomeric composition. In
certain embodiments, the first process comprises: a) blending at
least one primary elastomer, at least one cellulose ester, and,
optionally, one or more fillers for a sufficient time and
temperature to disperse the cellulose ester throughout the primary
elastomer so as to produce the elastomeric composition. A
sufficient temperature for blending the cellulose ester and the
primary elastomer can be the flow temperature of the cellulose
ester, which is higher than the Tg of the cellulose ester by at
least about 10.degree. C., 15.degree. C., 20.degree. C., 25.degree.
C., 30.degree. C., 35.degree. C., 40.degree. C., 45.degree. C., or
50.degree. C. The temperature of the blending can be limited by the
primary elastomer's upper processing temperature range and the
lower processing temperature range of the cellulose ester.
[0088] The primary elastomer, cellulose ester, fillers, and
additives can be added or combined in any order during the process.
In one embodiment, the cellulose ester can be modified with a
plasticizer and/or compatibilizer prior to being blended with the
primary elastomer.
[0089] In certain embodiments of the first process, at least a
portion of the blending can occur at temperatures of at least about
80.degree. C., 100.degree. C., 120.degree. C., 130.degree. C., or
140.degree. C. Additionally or alternatively, at least a portion of
the blending can occur at temperatures of not more than about
220.degree. C., 200.degree. C., 190.degree. C., 170.degree. C., or
160.degree. C.
[0090] During this first process, the cellulose esters can
effectively soften and/or melt, thus allowing the cellulose esters
to form into sufficiently small particle sizes under the specified
blending conditions. In such an embodiment, due to the small
particle sizes, the cellulose esters can be thoroughly dispersed
throughout the primary elastomer during the process. In one
embodiment, the particles of the cellulose ester in the elastomeric
composition have a spherical or near-spherical shape. As used
herein, a "near-spherical" shape is understood to include particles
having a cross-sectional aspect ratio of less than 2:1. In more
particular embodiments, the spherical and near-spherical particles
have a cross-sectional aspect ratio of less than 1.5:1, 1.2:1, or
1.1:1. The "cross-sectional aspect ratio" as used herein is the
ratio of the longest dimension of the particle's cross-section
relative to its shortest dimension. In a further embodiment, at
least about 75, 80, 85, 90, 95, or 99.9 percent of the particles of
cellulose esters in the elastomeric composition have a
cross-sectional aspect ratio of not more than about 10:1, 8:1, 6:1,
or 4:1.
[0091] In certain embodiments, at least about 75, 80, 85, 90, 95,
or 99.9 percent of the cellulose ester particles have a diameter of
not more than about 10, 8, 5, 4, 3, 2, or 1 .mu.m subsequent to
blending the cellulose ester with the primary elastomer.
[0092] In certain embodiments, the cellulose esters added at the
beginning of the process are in the form of a powder having
particle sizes ranging from 200 to 400 .mu.m. In such an
embodiment, subsequent to blending the cellulose ester into the
primary elastomer, the particle sizes of the cellulose ester can
decrease by at least about 50, 75, 90, 95, or 99 percent relative
to their particle size prior to blending.
[0093] In certain embodiments, the fillers can have a particle size
that is considerably smaller than the size of the cellulose ester
particles. For instance, the fillers can have an average particle
size that is not more than about 50, 40, 30, 20, or 10 percent of
the average particle size of the cellulose ester particles in the
elastomeric composition.
[0094] In the second process, a cellulose ester is first mixed with
a carrier elastomer to produce a cellulose ester concentrate (i.e.,
a cellulose ester masterbatch), which can subsequently be blended
with a primary elastomer to produce the elastomeric composition.
This second process may also be referred to as the "masterbatch
process." One advantage of this masterbatch process is that it can
more readily disperse cellulose esters having a higher Tg
throughout the primary elastomer. In one embodiment, the
masterbatch process involves mixing a high Tg cellulose ester with
a compatible carrier elastomer to produce a cellulose ester
concentrate, and then blending the cellulose ester concentrate with
at least one primary elastomer to produce the elastomeric
composition.
[0095] In certain embodiments, the masterbatch process comprises
the following steps: a) mixing at least one cellulose ester with at
least one carrier elastomer for a sufficient time and temperature
to mix the cellulose ester and the carrier elastomer to thereby
produce a cellulose ester concentrate; and b) blending the
cellulose ester concentrate and at least one primary elastomer to
produce the elastomeric composition. A sufficient temperature for
mixing the cellulose ester and the carrier elastomer can be the
flow temperature of the cellulose ester, which is higher than the
Tg of the cellulose ester by at least about 10.degree. C.,
15.degree. C., 20.degree. C., 25.degree. C., 30.degree. C.,
35.degree. C., 40.degree. C., 45.degree. C., or 50.degree. C. In
one embodiment of the masterbatch process, the cellulose ester has
a Tg of at least about 90.degree. C., 95.degree. C., 100.degree.
C., 105.degree. C., or 110.degree. C. Additionally or
alternatively, the cellulose ester can have a Tg of not more than
about 200.degree. C., 180.degree. C., 170.degree. C., 160.degree.
C., or 150.degree. C. In a further embodiment, at least a portion
of the mixing of step (a) occurs at a temperature that is at least
10.degree. C., 15.degree. C., 20.degree. C., 30.degree. C.,
40.degree. C., or 50.degree. C. greater than the temperature of the
blending of step (b).
[0096] In certain embodiments, at least a portion of the mixing of
the cellulose ester and the carrier elastomer occurs at a
temperature of at least about 170.degree. C., 180.degree. C.,
190.degree. C., 200.degree. C., or 210.degree. C. Additionally or
alternatively, at least a portion of the mixing of the cellulose
ester and the carrier elastomer occurs at a temperature below
260.degree. C., 250.degree. C., 240.degree. C., 230.degree. C., or
220.degree. C.
[0097] In certain embodiments, at least a portion of the blending
of the cellulose ester concentrate and the primary elastomer occurs
at a temperature that will not degrade the primary elastomer. For
instance, at least a portion of the blending can occur at a
temperature of not more than about 180.degree. C., 170.degree. C.,
160.degree. C., or 150.degree. C.
[0098] Fillers and/or additives can be added during any step of the
masterbatch process. In one embodiment, the cellulose ester can be
modified with a plasticizer or compatibilizer prior to the
masterbatch process.
[0099] In certain embodiments, at least a portion of the cellulose
ester concentrate can be subjected to fibrillation prior to being
blended with the primary elastomer. In such embodiments, the
resulting fibrils of the cellulose ester concentrate can have an
aspect ratio of at least about 2:1, 4:1, 6:1, or 8:1. In an
alternative embodiment, at least a portion of the cellulose ester
concentrate can be pelletized or granulated prior to being blended
with the primary elastomer.
[0100] In certain embodiments, the cellulose ester concentrate can
comprise at least about 10, 15, 20, 25, 30, 35, or 40 weight
percent of at least one cellulose ester. Additionally or
alternatively, the cellulose ester concentrate can comprise not
more than about 90, 85, 80, 75, 70, 65, 60, 55, or 50 weight
percent of at least one cellulose ester. In one embodiment, the
cellulose ester concentrate can comprise at least about 10, 15, 20,
25, 30, 35, or 40 weight percent of at least one carrier elastomer.
Additionally or alternatively, the cellulose ester concentrate can
comprise not more than about 90, 85, 80, 75, 70, 65, 60, 55, or 50
weight percent of at least one carrier elastomer.
[0101] Similar to the first process, the cellulose esters can
effectively soften and/or melt during the masterbatch process, thus
allowing the cellulose esters to form into sufficiently small
particle sizes under the specified blending conditions. In such an
embodiment, due to the small particle sizes, the cellulose esters
can be thoroughly dispersed throughout the elastomeric composition
after the process. In one embodiment, the particles of cellulose
ester in the elastomeric composition have a spherical or
near-spherical shape. In one embodiment, subsequent to blending the
cellulose ester concentrate with the primary elastomer, the
cellulose esters are in the form of spherical and near-spherical
particles having a cross-sectional aspect ratio of less than 2:1,
1.5:1, 1.2:1, or 1.1:1. In a further embodiment, subsequent to
blending the cellulose ester concentrate with the primary
elastomer, at least about 75, 80, 85, 90, 95, or 99.9 percent of
the particles of cellulose esters have a cross-sectional aspect
ratio of not more than about 2:1, 1.5:1, 1.2:1, or 1.1:1.
[0102] In certain embodiments, at least about 75, 80, 85, 90, 95,
or 99.9 percent of the cellulose ester particles have a diameter of
not more than about 10, 8, 5, 4, 3, 2, or 1 .mu.m subsequent to
blending the cellulose ester concentrate with the primary
elastomer.
[0103] In certain embodiments, the cellulose esters added at the
beginning of the masterbatch process are in the form of a powder
having particle sizes ranging from 200 to 400 .mu.m. In such an
embodiment, subsequent to blending the cellulose ester concentrate
with the primary elastomer, the particle sizes of the cellulose
ester can decrease by at least about 90, 95, 98, 99, or 99.5
percent relative to their particle size prior to the masterbatch
process.
[0104] The carrier elastomer can be virtually any uncured elastomer
that is compatible with the primary elastomer and that can be
processed at a temperature exceeding 160.degree. C. The carrier
elastomer can comprise, for example, styrene block copolymers,
polybutadienes, natural rubbers, synthetic rubbers, acrylics,
maleic anhydride modified styrenics, recycled rubber, crumb rubber,
powdered rubber, isoprene rubber, nitrile rubber, and combinations
thereof. The styrene block copolymers can include, for example,
styrene-butadiene block copolymers and styrene ethylene-butylene
block copolymers having a styrene content of at least about 5, 10,
or 15 weight percent and/or not more than about 40, 35, or 30
weight percent. In one embodiment, the carrier elastomers have a Tg
that is less than the Tg of the cellulose ester.
[0105] In certain embodiments, the carrier elastomer comprises
styrene block copolymers, polybutadienes, natural rubbers,
synthetic rubbers, acrylics, maleic anhydride modified styrenics,
and combinations thereof. In one embodiment, the carrier elastomer
comprises 1,2 polybutadiene. In another embodiment, the carrier
elastomer comprises a styrene block copolymer. In yet another
embodiment, the carrier elastomer comprises a maleic
anhydride-modified styrene ethylene-butylene elastomer.
[0106] In certain embodiments, the melt viscosity ratio of the
cellulose ester to the carrier elastomer is at least about 0.1,
0.2, 0.3, 0.5, 0.8, or 1.0 as measured at 170.degree. C. and a
shear rate of 400 s.sup.-1. Additionally or alternatively, the melt
viscosity ratio of the cellulose ester to the carrier elastomer is
not more than about 2, 1.8, 1.6, 1.4, or 1.2 as measured at
170.degree. C. and a shear rate of 400 s.sup.-1.
[0107] In certain embodiments, the melt viscosity ratio of the
cellulose ester concentrate to the primary elastomer is at least
about 0.1, 0.2, 0.3, 0.5, 0.8, or 1.0 as measured at 160.degree. C.
and a shear rate of 200 s.sup.-1. Additionally or alternatively,
the melt viscosity ratio of the cellulose ester concentrate to the
primary elastomer is not more than about 2, 1.8, 1.6, 1.4, or 1.2
as measured at as measured at 160.degree. C. and a shear rate of
200 s.sup.-1.
[0108] In certain embodiments, the cellulose ester exhibits a melt
viscosity of at least about 75,000, 100,000, or 125,000 poise as
measured at 170.degree. C. and a shear rate of 1 rad/sec.
Additionally or alternatively, the cellulose ester can exhibit a
melt viscosity of not more than about 1,000,000, 900,000, or
800,000 poise as measured at 170.degree. C. and a shear rate of 1
rad/sec. In another embodiment, the carrier elastomer exhibits a
melt viscosity of at least about 75,000, 100,000, or 125,000 poise
as measured at 170.degree. C. and a shear rate of 1 rad/sec.
Additionally or alternatively, the carrier elastomer can exhibit a
melt viscosity of not more than about 2,000,000, 1,750,000, or
1,600,000 poise as measured at 170.degree. C. and a shear rate of 1
rad/sec.
[0109] In certain embodiments, the cellulose ester exhibits a melt
viscosity of at least about 25,000, 40,000, or 65,000 poise as
measured at 170.degree. C. and a shear rate of 10 rad/sec.
Additionally or alternatively, the cellulose ester can exhibit a
melt viscosity of not more than about 400,000, 300,000, or 200,000
poise as measured at 170.degree. C. and a shear rate of 10 rad/sec.
In another embodiment, the carrier elastomer exhibits a melt
viscosity of at least about 20,000, 30,000, or 40,000 poise as
measured at 170.degree. C. and a shear rate of 10 rad/sec.
Additionally or alternatively, the carrier elastomer can exhibit a
melt viscosity of not more than about 500,000, 400,000, or 300,000
poise as measured at 170.degree. C. and a shear rate of 10
rad/sec.
[0110] In certain embodiments, the cellulose ester exhibits a melt
viscosity of at least about 10,000, 15,000, or 20,000 poise as
measured at 170.degree. C. and a shear rate of 100 rad/sec.
Additionally or alternatively, the cellulose ester can exhibit a
melt viscosity of not more than about 100,000, 75,000, or 50,000
poise as measured at 170.degree. C. and a shear rate of 100
rad/sec. In another embodiment, the carrier elastomer exhibits a
melt viscosity of at least about 10,000, 15,000, or 20,000 poise as
measured at 170.degree. C. and a shear rate of 100 rad/sec.
Additionally or alternatively, the carrier elastomer can exhibit a
melt viscosity of not more than about 100,000, 75,000, or 50,000
poise as measured at 170.degree. C. and a shear rate of 100
rad/sec.
[0111] In certain embodiments, the cellulose ester exhibits a melt
viscosity of at least about 2,000, 5,000, or 8,000 poise as
measured at 170.degree. C. and a shear rate of 400 rad/sec.
Additionally or alternatively, the cellulose ester can exhibit a
melt viscosity of not more than about 30,000, 25,000, or 20,000
poise as measured at 170.degree. C. and a shear rate of 400
rad/sec. In another embodiment, the carrier elastomer exhibits a
melt viscosity of at least about 1,000, 4,000, or 7,000 poise as
measured at 170.degree. C. and a shear rate of 400 rad/sec.
Additionally or alternatively, the carrier elastomer can exhibit a
melt viscosity of not more than about 30,000, 25,000, or 20,000
poise as measured at 170.degree. C. and a shear rate of 400
rad/sec.
[0112] In certain embodiments, the carrier elastomer contains
little or no nitrile groups. As used herein, the carrier elastomer
is considered a "non-nitrile" carrier elastomer when nitrile
monomers make up less than 10 weight percent of the carrier
elastomer. In one embodiment, the carrier elastomer contains no
nitrile groups.
[0113] In one embodiment, the carrier elastomer is the same as the
primary elastomer. In another embodiment, the carrier elastomer is
different from the primary elastomer.
[0114] The elastomeric compositions produced using either of the
above processes can be subjected to curing to thereby produce a
cured elastomeric composition. The curing can be accomplished using
any conventional method, such as curing under conditions of
elevated temperature and pressure for a suitable period of time.
For example, the curing process can involve subjecting the
elastomeric composition to a temperature of at least 160.degree. C.
over a period of at least 15 minutes. Examples of curing systems
that can be used include, but are not limited to, sulfur-based
systems, resin-curing systems, soap/sulfur curing systems, urethane
crosslinking agents, bisphenol curing agents, silane crosslinking,
isocyanates, poly-functional amines, high-energy radiation, metal
oxide crosslinking, and/or peroxide cross-linking.
[0115] The mixing and blending of the aforementioned processes can
be accomplished by any method known in the art that is sufficient
to mix cellulose esters and elastomers. Examples of mixing
equipment include, but are not limited to, Banbury mixers,
Brabender mixers, roll mills, planetary mixers, single screw
extruders, and twin screw extruders. The shear energy during the
mixing is dependent on the combination of equipment, blade design,
rotation speed (rpm), and mixing time. The shear energy should be
sufficient for breaking down softened/melted cellulose ester to a
small enough size to disperse the cellulose ester throughout the
primary elastomer. For example, when a Banbury mixer is utilized,
the shear energy and time of mixing can range from about 5 to about
15 minutes at 100 rpms. In certain embodiments of the present
invention, at least a portion of the blending and/or mixing stages
discussed above can be carried out at a shear rate of at least
about 50, 75, 100, 125, or 150 s.sup.-1. Additionally or
alternatively, at least a portion of the blending and/or mixing
stages discussed above can be carried out at a shear rate of not
more than about 1,000, 900, 800, 600, or 550 s.sup.-1.
[0116] It is known in the art that the efficiency of mixing two or
more viscoelastic materials can depend on the ratio of the
viscosities of the viscoelastic materials. For a given mixing
equipment and shear rate range, the viscosity ratio of the
dispersed phase (cellulose ester, fillers, and additives) and
continuous phase (primary elastomer) should be within specified
limits for obtaining adequate particle size. In one embodiment of
the invention where low shear rotational shearing equipment is
utilized, such as, Banbury and Brabender mixers, the viscosity
ratio of the dispersed phase (e.g., cellulose ester, fillers, and
additives) to the continuous phase (e.g., primary elastomer) can
range from about 0.001 to about 5, from about 0.01 to about 5, and
from about 0.1 to about 3. In yet another embodiment of the
invention where high shear rotational/extensional shearing
equipment is utilized, such as, twin screw extruders, the viscosity
ratio of the dispersed phase (e.g., cellulose ester, fillers, and
additives) to the continuous phase (e.g., primary elastomer) can
range from about 0.001 to about 500 and from about 0.01 to about
100.
[0117] It is also known in the art that when mixing two or more
viscoelastic materials, the difference between the interfacial
energy of the two viscoelastic materials can affect the efficiency
of mixing. Mixing can be more efficient when the difference in the
interfacial energy between the materials is minimal. In one
embodiment of the invention, the surface tension difference between
the dispersed phase (e.g., cellulose ester, fillers, and additives)
and continuous phase (e.g., primary elastomer) is less than about
100 dynes/cm, less than 50 dynes/cm, or less than 20 dynes/cm.
(F) Elastomeric Compositions
[0118] The elastomeric compositions of the present invention can
exhibit a number of improvements associated with processability,
strength, modulus, and elasticity.
[0119] In certain embodiments, the uncured elastomeric composition
exhibits a Mooney Viscosity as measured at 100.degree. C. and
according to ASTM D 1646 of not more than about 110, 105, 100, 95,
90, or 85 AU. A lower Mooney Viscosity makes the uncured
elastomeric composition easier to process. In another embodiment,
the uncured elastomeric composition exhibits a Phillips Dispersion
Rating of at least 6.
[0120] In certain embodiments, the uncured elastomeric composition
exhibits a scorch time of at least about 1.8, 1.9, 2.0, 2.1, or 2.2
Ts2, min. A longer scorch time enhances processability in that it
provides a longer time to handle the elastomeric composition before
curing starts. The scorch time of the samples was tested using a
cure rheometer (Oscillating Disk Rheometer (ODR)) and was performed
according to ASTM D 2084. As used herein, "ts2" is the time it
takes for the torque of the rheometer to increase 2 units above the
minimum value and "tc90" is the time to it takes to reach 90 weight
percent of the difference between minimum to maximum torque. In
another embodiment, the uncured elastomeric composition exhibits a
cure time of not more than about 15, 14, 13, 12, 11, or 10 tc90,
min. A shorter cure time indicates improved processability because
the elastomeric compositions can be cured at a faster rate, thus
increasing production.
[0121] In certain embodiments, the cured elastomeric composition
exhibits a Dynamic Mechanical Analysis ("DMA") strain sweep modulus
as measured at 5% strain and 30.degree. C. of at least about
1,400,000, 1,450,000, 1,500,000, 1,600,000, 1,700,000, or 1,800,000
Pa. A higher DMA strain sweep modulus indicates a higher
modulus/hardness. The DMA Strain Sweep is tested using a Metravib
DMA150 dynamic mechanical analyzer under 0.001 to 0.5 dynamic
strain at 13 points in evenly spaced log steps at 30.degree. C. and
10 Hz.
[0122] In certain embodiments, the cured elastomeric composition
exhibits a molded groove tear as measured according to ASTM D624 of
at least about 120, 125, 130, 140, 150, 155, 160, 165, or 170
lbf/in.
[0123] In certain embodiments, the cured elastomeric composition
exhibits a peel tear as measured according to ASTM D1876-01 of at
least about 80, 85, 90, 95, 100, 110, 120, or 130 lbf/in.
[0124] In certain embodiments, the cured elastomeric composition
exhibits a break strain as measured according to ASTM D412 of at
least about 360, 380, 400, 420, 425, or 430 percent. In another
embodiment, the cured elastomer composition exhibits a break stress
as measured according to ASTM D412 of at least 2,600, 2,800, 2,900,
or 3,000 psi. The break strain and break stress are both indicators
of the toughness and stiffness of the elastomeric compositions.
[0125] In certain embodiments, the cured elastomeric composition
exhibits a tan delta at 0.degree. C. and 5% strain in tension of
not more than about 0.100, 0.105, 0.110, or 0.115. In another
embodiment, the cured elastomeric composition exhibits a tan delta
at 30.degree. C. and 5% strain in shear of not more than about
0.25, 0.24, 0 . . . 23, 0.22, or 0.21. The tan deltas were measured
using a TA Instruments dynamic mechanical analyzer to complete
temperature sweeps using tensile geometry. The tan deltas (=E''/E')
(storage modulus (E') and loss modulus (E'')) were measured as a
function of temperature from -80.degree. C. to 120.degree. C. using
10 Hz frequency, 5% static, and 0.2% dynamic strain.
[0126] In certain embodiments, the cured elastomeric composition
exhibits an adhesion strength at 100.degree. C. of at least about
30, 35, 40, or 45 lbf/in. The adhesion strength at 100.degree. C.
is measured using 180-degree T-peel geometry.
[0127] In certain embodiments, the cured elastomeric composition
exhibits a Shore A hardness of at least about 51, 53, 55, or 57.
The Shore A hardness is measured according to ASTM D2240.
(G) Products Incorporation the Elastomeric Compositions
[0128] The elastomeric compositions of the present invention can be
incorporated into various types of articles.
[0129] In certain embodiments, the elastomeric composition is
formed into a tire and/or a tire component. The tire component can
comprise, for example, tire tread, subtread, undertread, body
plies, belts, overlay cap plies, belt wedges, shoulder inserts,
tire apex, tire sidewalls, bead fillers, and any other tire
component that contains an elastomer. In one embodiment, the
elastomeric composition is formed into tire tread, tire sidewalls,
and/or bead fillers.
[0130] In certain embodiments, the elastomeric composition is
incorporated into non-tire applications. Non-tire applications
include, for example, a blow-out preventer, fire hoses, weather
stripping, belts, injection molded parts, footwear, pharmaceutical
closures, plant lining, flooring, power cables, gaskets, seals, and
architectural trims. In particular, the elastomeric compositions
can be utilized in various oil field applications such as, for
example, blowout preventers, pump pistons, well head seals, valve
seals, drilling hoses, pump stators, drill pipe protectors,
down-hole packers, inflatable packers, drill motors, O-Rings, cable
jackets, pressure accumulators, swab cups, and bonded seals.
[0131] This invention can be further illustrated by the following
examples of preferred embodiments thereof, although it will be
understood that these examples are included merely for purposes of
illustration and are not intended to limit the scope of the
invention unless otherwise specifically indicated.
EXAMPLES
Example 1
[0132] Elastomeric compositions containing varying amounts of
cellulose ester were compared to elastomeric compositions not
containing any cellulose ester. The elastomeric compositions were
produced according to the formulations and parameters in TABLE 1.
Examples 1 and 2 contained varying amounts of cellulose ester,
while no cellulose ester was added to Comparative Examples 1 and
2.
TABLE-US-00001 TABLE 1 Comparative Comparative Ingredient Component
Example 1 Example 2 Example 1 Example 2 STAGE 1 BUNA VSL S-SBR
89.38 89.38 89.38 89.38 5025-2 HM extended with 37.5 phr TDAE BUNA
CB 22 PBD Rubber 35 35 35 35 ULTRASIL 7000 Silica 65 65 65 65 GR
N234 Carbon black 15 15 15 15 Si 266 Coupling agent 5.08 5.08 5.08
5.08 SUNDEX 790 Aromatic oil -- -- -- 8.75 Stearic acid Cure
Activator 1.5 1.5 1.5 1.5 Product of Stage 1 MB1 210.96 210.96
210.96 219.71 STAGE 2 Product of Stage 1 MB1 210.96 210.96 210.96
219.71 CAB-551-0.01 Cellulose Ester 7 15 -- -- Si 69 Coupling agent
0.546 1.17 -- -- Zinc oxide Cure activator 1.9 1.9 1.9 1.9 OKERIN
WAX Microcrystalline 1.5 1.5 1.5 1.5 7240 wax SANTOFLEX Antioxidant
2 2 2 2 6PPD Product of Stage 2 MB2 223.91 232.53 216.36 225.11
STAGE 3 Product of Stage 2 MB2 223.91 232.53 216.36 225.11 Sulfur
Cross-linker 1.28 1.28 1.28 1.28 SANTOCURE Accelerator 1.1 1.1 1.1
1.1 CBS PERKACIT Accelerator 1.28 1.28 1.28 1.28 DPG-grs TOTAL
227.57 236.19 220.02 228.77
[0133] The elastomeric compositions were prepared by first blending
a solution of styrene-butadiene rubber extended with 37.5 phr of
TDAE oil (Buna VSL 5025-2 HM from Lanxess, Cologne, Germany), a
polybutadiene rubber (Buna C 22 from Lanxess, Cologne, Germany);
silica, carbon black, a coupling agent (Si 266), and a cure
activator (i.e., stearic acid) in a Banbury mixer to create a first
masterbatch. In addition, aromatic processing oil (Sundex.RTM. 790
from Petronas Lubricants, Belgium) was added to the first
masterbatch used to produce Comparative Example 2. The first
masterbatches were blended and produced according to the parameters
listed in Stage 1 of TABLES 1 and 2.
[0134] The first masterbatch for all examples was subsequently
blended with a cure activator, a microcrystalline wax, and an
antioxidant to produce a second masterbatch. Additionally, a
cellulose ester (CAB-551-0.01 from Eastman Chemical Kingsport,
Tenn.) and a coupling agent (SI 69 from Evonik Degussa, Koln,
Germany) were added to the first masterbatches used to produce
Examples 1 and 2. The second masterbatches were blended and
produced according to the parameters listed in Stage 2 of TABLES 1
and 2.
[0135] The second masterbatch for all examples was blended with a
crosslinker and two different accelerators (Santocure.RTM. CBS and
Perkacit.RTM. DPG-grs from Solutia, St. Louis, Mo.). The second
masterbatches were processed according to the parameters listed in
Stage 3 of TABLES 1 and 2. After processing, the second
masterbatches were cured for 30 minutes at 160.degree. C.
TABLE-US-00002 TABLE 2 STAGE 1 STAGE 2 STAGE 3 Start 65.degree. C.
65.degree. C. 50.degree. C. Temperature Starting Rotor 65 65 60
Speed (RPM) Fill Factor 67% 64% 61% Ram Pressure 50 50 50 Mix
Sequence Add primary elastomers Add half of first master batch Add
half of second master After 1 minute, add 2/3 After 15 seconds, add
other batch silica + Si266 components and other half of first
master batch After 2 minutes, add 1/3 After 1 minute, sweep After
15 seconds, add sulfur, silica + other components accelerator
package, and other After 3 minutes, sweep After 1.5 minutes, adjust
rotor half of second master batch After 3.5 minutes, adjust speed
to increase temperature to After 1 minute, sweep rotor speed to
increase 150.degree. C. temperature to 160.degree. C. Dump
Conditions Hold for 2 minutes at Hold for 4 minutes at 150.degree.
C. Hold for 2.5 minutes at 110.degree. C. 160.degree. C. Total Time
6.5 minutes 7.5 minutes 3.75 minutes
Example 2
[0136] Various performance properties of the elastomeric
compositions produced in Example 1 were tested.
[0137] The break stress and break strain were measured as per ASTM
D412 using a Die C for specimen preparation. The specimen had a
width of 1 inch and a length of 4.5 inches. The speed of testing
was 20 inches/min and the gauge length was 63.5 mm (2.5 inch). The
samples were conditioned in the lab for 40 hours at 50%+/-5%
humidity and at 72.degree. F. (22.degree. C.).
[0138] The Mooney Viscosities were measured at 100.degree. C.
according to ASTM D 1646.
[0139] The Phillips Dispersion Rating was calculated by cutting the
samples with a razor blade and subsequently taking pictures at
30.times. magnification with an Olympus SZ60 Zoom Stereo Microscope
interfaced with a PAXCAM ARC digital camera and a Hewlett Packard
4600 color printer. The pictures of the samples were then compared
to a Phillips standard dispersion rating chart having standards
ranging from 1 (bad) to 10 (excellent).
[0140] The Dynamic Mechanical Analysis ("DMA") Strain Sweep was
tested using a Metravib DMA150 Dynamic Mechanical Analyzer in shear
deformation to perform a double strain sweep experiment that
utilized a simple shear of 10 mm.times.2 mm. The experimental
conditions were 0.001 to 0.5 dynamic strain at 13 points in evenly
spaced log steps at 30.degree. C. and 10 Hz.
[0141] The Hot Molded Groove Trouser Tear was measured at
100.degree. C. according to ASTM test method D624.
[0142] The Peel Tear (adhesion to self at 100.degree. C.) was
measured using 180.degree. T-peel geometry and according to ASTM
test method D1876-01 with a modification. The standard
1''.times.6'' peel test piece was modified to reduce the adhesion
test area with a Mylar window. The window size was
3''.times.0.125'' and the pull rate was 2''/min.
[0143] The results of these tests are depicted in TABLE 3 for each
elastomeric composition. TABLE 3 shows that the addition of
cellulose esters and aromatic processing oils can reduce the Mooney
Viscosity of the elastomeric composition, thus indicating better
processability. Comparative Example 1, which did not contain either
component, exhibited a high Mooney Viscosity, thus indicating
poorer processability. Further, the addition cellulose esters
increased the DMA Strain Sweep, thus these elastomeric compositions
exhibited improved hardness and handling properties. In contrast,
Comparative Example 2, which utilized an aromatic processing oil to
lower its Mooney Viscosity, exhibited a low DMA Strain Sweep. Thus,
while the aromatic processing oil led to a decrease in the Mooney
Viscosity, it resulted in an undesirable decrease in the
elastomeric composition's handling and hardness properties.
Moreover, elastomeric compositions containing cellulose esters
exhibited a higher tear strength, as depicted by the molded groove
tear and peel tear at 100.degree. C., relative to the comparative
examples. Furthermore, TABLE 3 shows that the addition of an
aromatic processing oil, like in Comparative Example 2, had little
to no impact on tear strength.
TABLE-US-00003 TABLE 3 Break Mooney Phillips DMA Strain Sweep
Molded Groove Peel Tear at Stress Break viscosity Dispersion (5%
strain in Tear at 100.degree. C. 100.degree. C. Sample (psi) Strain
% (AU) Rating shear) (Pa) (lbf/in) (lbf/in) Example 1 3031 432 90.9
7 1740000 172 102 Example 2 3017 447 88.4 6 1830000 160 135
Comparative 2915 358 98.1 6 1680000 126 81.1 Example 1 Comparative
2785 405 83.7 5 1400000 123 94 Example 2
Example 3
[0144] In this example, elastomeric compositions were produced
using the masterbatch process. A number of different cellulose
ester concentrates were prepared and subsequently combined with
elastomers to produce the elastomeric compositions.
[0145] In the first stage of the masterbatch process, cellulose
esters were bag blended with styrenic block copolymer materials and
then fed using a simple volumetric feeder into the chilled feed
throat of a Leitstritz twin screw extruder to make cellulose ester
concentrates (i.e., masterbatches). The various properties of the
cellulose esters and styrenic block copolymer materials utilized in
this first stage are depicted in TABLES 4 and 5. All of the recited
cellulose esters in TABLE 4 are from Eastman Chemical Company,
Kingsport, Tenn. All of the styrenic block copolymers in TABLE 5
are from Kraton Polymers, Houston, Tex. The Leistritz extruder is
an 18 mm diameter counter-rotating extruder having an L/D of 38:1.
Material was typically extruded at 300 to 350 RPM with a volumetric
feed rate that maintained a screw torque value greater than 50
weight percent. Samples were extruded through a strand die, and
quenched in a water bath, prior to being pelletized. Relative
loading levels of cellulose esters and styrenic block copolymers
were varied to determine affect on mixing efficiency.
[0146] In the second stage, these cellulose ester concentrates were
mixed with a base rubber formulation using a Brabender batch mixer
equipped with roller type high shear blades. The base rubber was a
blend of a styrene butadiene rubber (Buna 5025-2, 89.4 pph) and
polybutadiene rubber (Buna CB24, 35 pph). Mixing was performed at a
set temperature of 160.degree. C. and a starting rotor speed of 50
RPM. RPM was decreased as needed to minimize overheating due to
excessive shear. The cellulose ester concentrate loading level was
adjusted so that there was about 20 weight percent cellulose ester
in the final mix.
[0147] For the Comparative Examples, cellulose ester and
plasticizer (i.e., no rubber) were first combined together in a
Brabender batch mixer equipped with roller high shear blades in
order to form a masterbatch. Plasticizer was added to enhance flow
and lower viscosity as it has been observed that high viscosity
cellulose esters will not mix at the processing temperature of the
rubber (i.e., 150 to 160.degree. C.). Mixing was performed for
approximately 10 to 15 minutes at 160.degree. C. and 50 RPM. Upon
completion, the sample was removed and cryo-ground to form a
powder.
[0148] In the next stage, 20 weight percent of the cellulose
ester/plasticizer masterbatch was added to the rubber formulation
using the same Brabender mixer at 160.degree. C. and 50 RPM. The
masterbatch was added 30 seconds after the rubber compound had been
fully introduced into the mixer. Mixing was performed for
approximately 10 minutes after all ingredients had been added. The
sample was then removed and tested.
[0149] The particle sizes in the dispersion were measured using a
compound light microscope (typically 40.times.). The samples could
be cryo-polished to improve image quality and the microscope could
run in differential interference contrast mode to enhance
contrast.
[0150] The glass transition temperatures were measured using a DSC
with a scanning rate of 20.degree. C./minute.
[0151] The base formulations for all samples tested and produced as
described below are depicted in TABLES 6A, 6B, and 6C.
TABLE-US-00004 TABLE 4 Falling Melting Ball Tg Range Grade Type
Viscosity (.degree. C.) (.degree. C.) CAB Cellulose acetate
butyrate 0.1 123 155-165 381-0.1 CAB Cellulose acetate butyrate 0.5
130 155-165 381-0.5 CAB 381-2 Cellulose acetate butyrate 2 133
171-184 CAB 381-6 Cellulose acetate butyrate 6 135 184 to 190 (est)
(est) CAB 381-20 Cellulose acetate butyrate 6 141 195-204 CAP
482-0.5 Cellulose acetate propionate 0.5 142 188-210 CAP 482-2
Cellulose acetate propionate 2 143 188-210 CAP 482-6 Cellulose
acetate propionate 6 144 188-210 (est) (est) CAP 482-20 Cellulose
acetate propionate 6 147 188-210 CA 398-30 Cellulose acetate 30 180
230-250
TABLE-US-00005 TABLE 5 MI @ Diblock Shore MA Grade Type Styrene
200.degree. C. content Hardness bound D1118KT Diblock styrene/ 33
wt % 10 78 74 Na butadiene D1102KT Triblock styrene/ 28 wt % 14 17
66 Na butadiene D1101KT Triblock styrene/ 31 wt % <1 16 wt % 69
Na butadiene FG1924GT Triblock, 13 wt % 40 @ na 49 0.7 to 1.3 wt %
styrene ethylene/ 230.degree. C. butylene FG1901G Triblock, 30 wt %
22 @ na 71 1.4 to 2.0 wt % styrene ethylene/ 230.degree. C.
butylene
Example 3(a)
[0152] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAB 381-0.1 and 60
weight percent of Kraton FG1924. The materials were compounded
using a medium shear screw design at max zone temperatures of
200.degree. C. and a residence time of less than one minute. The
cellulose ester concentrate was combined with the base rubber
formulation at a 50:50 weight ratio and mixed in a Brabender mixer.
The final elastomeric composition contained 50 weight percent of
base rubber, 30 weight percent of Kraton FG 1924, and 20 weight
percent of CAB 381-0.1. The particles were evenly dispersed and had
particle sizes of less than 1 micron.
Example 3(b)
[0153] In this example, a cellulose ester concentrate was produced
that contained 60 weight percent of Eastman CAB 381-0.1 and 40
weight percent of Kraton FG1924. The materials were compounded
using a medium shear screw design at max zone temperatures of
200.degree. C. and a residence time less of than one minute. The
cellulose ester concentrate was combined with the base rubber
formulation at a 33.3/66.7 weight ratio and mixed in a Brabender
mixer. The final formulation contained 66.7 weight percent of the
base rubber, 13.3 weight percent of Kraton FG 1924, and 20 weight
percent of CAB 381-0.1. The particles were evenly dispersed and had
particle sizes of less than 3 microns, with most particles being
less than 1 micron.
Example 3(c)
[0154] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAB 381-0.5 and 60
weight percent of Kraton FG1924. The materials were compounded
using a medium shear screw design at max zone temperatures of
225.degree. C. and a residence time of less than one minute. The
cellulose ester concentrate was combined with the base rubber
formulation at a 50/50 weight ratio and mixed in a Brabender mixer.
The final formulation contained 50 weight percent of base rubber,
30 weight percent of Kraton FG 1924, and 20 weight percent of CAB
381-0.5. The particles were evenly dispersed and had a particle
size less than 1 micron.
Example 3(d)
[0155] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAB 381-2 and 60 weight
percent of Kraton FG1924. The materials were compounded using a
medium shear screw design at max zone temperatures of 250.degree.
C. and a residence time of less than one minute. The cellulose
ester concentrate was combined with the base rubber formulation at
a 50/50 weight ratio and mixed in a Brabender mixer. The final
formulation contained 50 weight percent of base rubber, 30 weight
percent of Kraton FG 1924, and 20 weight percent of CAB 381-2. The
particles were evenly dispersed and had particle sizes of less than
1 micron.
Example 3(e)
[0156] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAB 381-0.1 and 60
weight percent of Kraton D1102. The materials were compounded using
a medium shear screw design at max zone temperatures of 200.degree.
C. and a residence time of less than one minute. The cellulose
ester concentrate was combined with the base rubber formulation at
a 50/50 weight ratio and mixed in a Brabender mixer. The final
formulation contained 50 weight percent of base rubber, 30 weight
percent of Kraton D1102, and 20 weight percent of CAB 381-0.1. The
particles were evenly dispersed and had particle sizes of less than
3 microns.
Example 3(f)
[0157] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAB 381-0.1 and 60
weight percent of Kraton D1101. The materials were compounded using
a medium shear screw design at max zone temperatures of 200.degree.
C. and a residence time of less than one minute. The cellulose
ester concentrate was combined with the base rubber formulation at
a 50/50 weight ratio and mixed in a Brabender mixer. The final
formulation contained 50 weight percent of base rubber, 30 weight
percent of Kraton D1101, and 20 weight percent of CAB 381-0.1. The
particles were evenly dispersed and had particle sizes of less than
5 microns.
Example 3(g)
[0158] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAB 381-0.1 and 60
weight percent of Kraton D1118. The materials were compounded using
a medium shear screw design at max zone temperatures of 200.degree.
C. and a residence time of less than one minute. The cellulose
ester concentrate was combined with the base rubber formulation at
a 50/50 weight ratio and mixed in a Brabender mixer. The final
formulation contained 50 weight percent of base rubber, 30 weight
percent of Kraton D1118, and 20 weight percent of CAB 381-0.1. The
particles were evenly dispersed and had particle sizes less than 3
microns.
Example 3(h)
[0159] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAP 482-0.5 and 60
weight percent of Kraton FG 1924. The materials were compounded
using a medium shear screw design at max zone temperatures of
250.degree. C. and a residence time of less than one minute. The
cellulose ester concentrate was combined with the base rubber
formulation at a 50/50 weight ratio and mixed in a Brabender mixer.
The final formulation contained 50 weight percent of base rubber,
30 weight percent of Kraton FG 1924, and 20 weight percent of CAP
482-0.5. The particles were evenly dispersed and had particle sizes
of less than 1 micron.
Example 3(i)
[0160] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CA 398-3 and 60 weight
percent of Kraton FG 1924. The materials were compounded using a
medium shear screw design at max zone temperatures of 250.degree.
C. and a residence time of less than one minute. The cellulose
ester concentrate was combined with the base rubber formulation at
a 50/50 weight ratio and mixed in a Brabender mixer. The final
formulation contained 50 weight percent of base rubber, 30 weight
percent of Kraton FG 1924, and 20 weight percent of CA 398-3. The
particles were evenly dispersed and had particle sizes less than 3
microns.
Example 3(j)
[0161] In this example, a cellulose ester concentrate was produced
that contained 40 weight of percent Eastman CAB 381-0.1 and 60
weight percent of Kraton FG1901. The materials were compounded
using a medium shear screw design at max zone temperatures of
200.degree. C. and a residence time of less than one minute. The
cellulose ester concentrate was combined with the base rubber
formulation at a 50/50 weight ratio and mixed in a Brabender mixer.
The final formulation contained 50 weight percent of base rubber,
30 weight percent of Kraton FG 1901, and 20 weight percent of CAB
381-0.1. The particles were evenly dispersed and had particle sizes
of less than 1 micron.
Example 3(k)
[0162] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAB 381-0.5 and 60
weight percent of Kraton FG1901. The materials were compounded
using a medium shear screw design at max zone temperatures of
225.degree. C. and a residence time of less than one minute. The
cellulose ester concentrate was combined with the base rubber
formulation at a 50/50 weight ratio and mixed in a Brabender mixer.
The final formulation contained 50 weight percent of base rubber,
30 weight percent Kraton FG 1901, and 20 weight percent of CAB
381-0.5. The particles were evenly dispersed and had particle sizes
of less than 1 micron.
Example 3(l)
[0163] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAB 381-2 and 60 weight
percent of Kraton FG1901. The materials were compounded using a
medium shear screw design at max zone temperatures of 250.degree.
C. and a residence time of less than one minute. The cellulose
ester concentrate was combined with the base rubber formulation at
a 50/50 weight ratio and mixed in a Brabender mixer. The final
formulation contained 50 weight percent of base rubber, 30 weight
percent of Kraton FG 1901, and 20 weight percent of CAB 381-2. The
particles were evenly dispersed and had particle sizes of less than
1 micron.
Example 3(m)
[0164] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CAP 482-0.5 and 60
weight percent of Kraton FG1901. The materials were compounded
using a medium shear screw design at max zone temperatures of
250.degree. C. and a residence time of less than one minute. The
cellulose ester concentrate was combined with the base rubber
formulation at a 50/50 weight ratio and mixed in a Brabender mixer.
The final formulation contained 50 weight percent of base rubber,
30 weight percent of Kraton FG 1901, and 20 weight percent of CAP
482-0.5. The particles were evenly dispersed and had particle sizes
of less than 3 microns.
Example 3(n)
[0165] In this example, a cellulose ester concentrate was produced
that contained 40 weight percent of Eastman CA 398-3 and 60 weight
percent of Kraton FG 1901. The materials were compounded using a
medium shear screw design at max zone temperatures of 250.degree.
C. and a residence time of less than one minute. The cellulose
ester concentrate was combined with the base rubber formulation at
a 50/50 weight ratio and mixed in a Brabender mixer. The final
formulation contained 50 weight percent of base rubber, 30 weight
percent of Kraton FG 1901, and 20 weight percent of CA 398-3. The
particles were evenly dispersed and had particle sizes of less than
1 micron.
Example 3(o)
[0166] In this example, 67 weight percent of Eastman CAB 381-20 was
melt blended with 33 weight percent of Eastman CAB 381-0.5 to
produce an estimated CAB 381-6 material having a falling ball
viscosity of 6. Subsequently, 40 weight percent of this cellulose
ester blend was melt blended with 60 weight percent of Kraton FG
1924. The materials were compounded using a medium shear screw
design at max zone temperatures of 200.degree. C. and a residence
time of less than one minute. The cellulose ester concentrate was
combined with the base rubber formulation at a 50/50 weight ratio
and mixed in a Brabender mixer. The final formulation contained 50
weight percent of base rubber, 30 weight percent of Kraton FG 1924,
and 20 weight percent of CAB 381-6. The particles were evenly
dispersed and had particle sizes of less than 3 microns.
Example 3(p)
[0167] In this example, 67 weight percent of Eastman CAP 482-20 was
melt blended with 33 weight percent of Eastman CAP 482-0.5 to
produce an estimated CAP 482-6 material. Subsequently, 40 weight
percent of this cellulose ester blend was melt blended with 60
weight percent of Kraton FG 1924. The materials were compounded
using a medium shear screw design at max zone temperatures of
200.degree. C. and a residence time of less than one minute. The
cellulose ester concentrate was combined with the base rubber
formulation at a 50/50 weight ratio and mixed in a Brabender mixer.
The final formulation contained 50 weight percent of base rubber,
30 weight percent of Kraton FG 1924, and 20 weight percent of CAP
482-6. The particles were evenly dispersed and had particle sizes
of less than 1 micron.
Example 3(q)
[0168] In this example, 67 weight percent of Eastman CAP 482-20 was
melt blended with 33 weight percent of Eastman CAP 482-0.5 to
produce an estimated CAP 482-6 material. Subsequently, 40 weight
percent of this cellulose ester blend was melt blended with 60
weight percent of Kraton D1102. The materials were compounded using
a medium shear screw design at max zone temperatures of 200.degree.
C. and a residence time of less than one minute. The cellulose
ester concentrate was combined with the base rubber formulation at
a 50/50 weight ratio and mixed in a Brabender mixer. The final
formulation contained 50 weight percent of base rubber, 30 weight
percent of Kraton D1102, and 20 weight percent of CAP 482-6. The
particles were evenly dispersed and had particle sizes of less than
5 microns.
Example 3(r)
[0169] In this example, 90 weight percent of Eastman CA 398-3 was
melt blended with 10 weight percent of triphenyl phosphate to
produce a plasticized cellulose acetate pre-blend. Subsequently, 40
weight percent of this plasticized cellulose acetate was melt
blended with 60 weight percent Kraton D1102. The materials were
compounded using a medium shear screw design at max zone
temperatures of 200.degree. C. and a residence time of less than
one minute. The cellulose ester concentrate was combined with the
base rubber formulation at a 66.7/33.3 weight ratio and mixed in a
Brabender mixer. The final formulation contained 33.3 weight
percent of base rubber, 40 weight percent of Kraton D1102, 20
weight percent of CA 398-3, and 6.67 weight percent triphenyl
phosphate. The particles were evenly dispersed and had particle
sizes of less than 3 microns.
Example 3(s)
[0170] In this example, 90 weight percent of Eastman CA 398-3 was
melt blended with 10 weight percent of triphenyl phosphate to
produce a plasticized cellulose acetate pre-blend. Subsequently, 40
weight percent of this plasticized cellulose acetate was melt
blended with 60 weight percent of Kraton FG 1924. The materials
were compounded using a medium shear screw design at max zone
temperatures of 200.degree. C. and a residence time of less than
one minute. The cellulose ester concentrate was combined with the
base rubber formulation at a 66.7/33.3 weight ratio and mixed in a
Brabender mixer. The final formulation contained 33.3 weight
percent of base rubber, 40 weight percent of Kraton FG 1924, 20
weight percent of CA 398-3, and 6.67 weight percent of triphenyl
phosphate. The particles were evenly dispersed and had particle
sizes of less than 1 micron.
Comparative Example 3(a)
[0171] In this example, a masterbatch was produced having 90 weight
percent of Eastman CAB 381-0.1 and 10 weight percent of dioctyl
adipate plasticizer. The CAB had a falling ball viscosity of 0.1
and the mixture had an estimated Tg of 95.degree. C. The
masterbatch was combined with the base rubber formulation at a
20/80 weight ratio and mixed in a Brabender mixer. This was done to
simulate "direct mixing" as is currently practiced in the art. Most
of the particles were evenly dispersed and had sizes predominantly
between 5 and 10 microns; however, a few particles showed
clustering in the 25 microns range.
Comparative Example 3(b)
[0172] Following the same procedure as in Comparative Example 3(a),
an attempt was made to mix Eastman CA 398-3 powder without
plasticizer into the rubber formulation. The CA had a falling ball
viscosity of 3 and a Tg of approximately 180.degree. C. Mixing
could not be performed because the CA would not soften at the
mixing temperature of 160.degree. C.
Comparative Example 3(c)
[0173] Following the same procedure as in Comparative Example 3(a),
a masterbatch was produced from a 50/50 mix of Eastman CA 398-3 and
polyethylene glycol plasticizer. The high level of plasticizer was
required in order to make the CA processable at 160.degree. C. The
Tg of the mixture was estimated to be less than 100.degree. C.
Particles partially dispersed but overall quality was poor with
large clumps of cellulose acetate being present having particle
sizes greater than 25 microns.
Comparative Example 3(d)
[0174] Following the same procedure as in Comparative Example 3(a),
a masterbatch was produced from a 75/25 mix of Eastman CAP 482-0.5
and dioctyl adipate plasticizer. The high level of plasticizer was
required in order to make the CAP processable at 160.degree. C. The
Tg of the mixture was estimated to be less than 100.degree. C.
Particles partially dispersed but overall quality was poor with
large clumps of cellulose acetate propionate being present having
particle sizes greater than 25 microns.
Comparative Example 3(e)
[0175] Following the same procedure as in Comparative Example 3(a),
a masterbatch was produced from a 80/20 mix of Eastman CAP 482-0.5
and polyethylene glycol plasticizer. The high level of plasticizer
was required in order to make the CAP processable at 160.degree. C.
The Tg of the mixture was estimated to be less than 100.degree. C.
Particles dispersed fairly well with most particles having sizes
predominantly between 5 and 15 microns.
TABLE-US-00006 TABLE 6A Example Example Example Example Example
Example Example Example Example Example Example 3(a) 3(b) 3(c) 3(d)
3(e) 3(f) 3(g) 3(h) 3(i) 3(j) 3(k) Cellulose Ester Concentrate
Formulations Cellulose Ester 40 60 40 40 40 40 40 40 40 40 40
Carrier 60 40 60 60 60 60 60 60 60 60 60 Elastomer Plasticizer --
-- -- -- -- -- -- -- -- -- -- CE 100 100 100 100 100 100 100 100
100 100 100 Concentrate (Total wt %) Mixing Ratios for Elastomeric
Compositions Base 50 66.7 50 50 50 50 50 50 50 50 50 Rubber CE 50
33.3 50 50 50 50 50 50 50 50 50 Concentrate Elastomeric 100 100 100
100 100 100 100 100 100 100 100 Composition (Total wt %) Final
Formulations of Produced Elastomeric Compositions Cellulose 20 20
20 20 20 20 20 20 20 20 20 Ester Carrier 30 13.3 30 30 30 30 30 30
30 30 30 Elastomer Base 50 66.7 50 50 50 50 50 50 50 50 50 Rubber
Dispersion <1 .mu.m <1 .mu.m <1 .mu.m <1 .mu.m <3
.mu.m <5 .mu.m <3 .mu.m <1 .mu.m <3 .mu.m <1 .mu.m
<1 .mu.m Particle Size
TABLE-US-00007 TABLE 6B Example Example Example Example Example
Example Example Example Comparative Comparative 3(l) 3(m) 3(n) 3(o)
3(p) 3(q) 3(r) 3(s) Example 3(a) Example 3(b) Cellulose Ester
Concentrate Formulations Cellulose Ester 40 40 40 40 40 40 36 36 90
-- Carrier Elastomer 60 60 60 60 60 60 60 60 -- -- Plasticizer --
-- -- -- -- -- 4 4 10 -- CE 100 100 100 100 100 100 100 100 100 --
Concentrate (Total wt %) Mixing Ratios for Elastomeric Compositions
Base 50 50 50 50 50 50 33.3 33.3 80 -- Rubber CE 50 50 50 50 50 50
66.7 66.7 20 -- Concentrate Elastomeric 100 100 100 100 100 100 100
100 100 -- Composition (Total wt %) Final Formulations of Produced
Elastomeric Compositions Cellulose 20 20 20 20 20 20 20 20 18 --
Ester Carrier 30 30 30 30 30 30 40 40 -- -- Elastomer Base 50 50 50
50 50 50 33.3 33.3 80 -- Rubber Plasticizer -- -- -- -- -- -- 6.67
6.67 2 -- Dispersion <1 .mu.m <3 .mu.m <1 .mu.m <3
.mu.m <1 .mu.m <5 .mu.m <3 .mu.m <1 .mu.m 5-10 .mu.m --
Particle Size
TABLE-US-00008 TABLE 6C Comparative Comparative Comparative Example
3(c) Example 3(d) Example 3(e) Cellulose Ester Concentrate
Formulations Cellulose 50 75 80 Ester Carrier -- -- -- Elastomer
Plasticizer 50 25 20 CE 100 100 100 Concentrate (Total wt %) Mixing
Ratios for Elastomeric Compositions Base 80 80 80 Rubber CE 20 20
20 Concentrate Elastomeric 100 100 100 Composition (Total wt %)
Final Formulations of Produced Elastomeric Compositions Cellulose
10 15 16 Ester Carrier -- -- -- Elastomer Base 80 80 80 Rubber
Plasticizer 10 5 4 Dispersion >25 .mu.m >25 .mu.m 10-15 .mu.m
Particle Size
Example 4
[0176] This example shows the advantages of using modified
cellulose esters with plasticizers in tire formulations compared to
using only cellulose esters. TABLE 7 shows the tire formulations
that were produced. TABLE 8 shows the cellulose ester/plasticizer
masterbatch formulations that were produced. The elastomeric
compositions were produced using the procedure parameters outlined
in TABLES 7 and 9.
[0177] TABLE 9 depicts the mixing conditions of the three stages.
The components were mixed in a Banbury mixer. After preparing the
elastomeric compositions, the composition was cured for T90+5
minutes at 160.degree. C.
TABLE-US-00009 TABLE 7 Ingredient Component CAB-1 CAB-2 CAB-3 STAGE
1 Buna VSL S-SBR 103.12 103.12 103.12 5025-2 extended with 37.5 phr
TDAE Buna CB24 PBD Rubber 25 25 25 Rhodia 1165 Silica 70 70 70 MP
N234 Carbon black 15 15 15 Si69 Coupling agent 5.47 5.47 5.47
Sundex .RTM. 790 Aromatic oil 5 5 5 Stearic acid Cure Activator 1.5
1.5 1.5 Product of MB1 210.9 210.9 210.9 Stage 1 STAGE 2 Product of
MB1 210.9 210.9 210.9 Stage 1 CE/Plasticizer CE-MB1 10 -- -- Blends
CE-MB2 -- 12.5 -- CE-MB3 -- -- 12.5 Si 69 Coupling agent 0.546 1.17
-- Zinc oxide Cure activator 1.9 1.9 1.9 Okerin .RTM. Wax
Microcrystalline 1.5 1.5 1.5 7240 wax Santoflex .RTM. Antioxidant 2
2 2 6PPD Strutkol .RTM. KK49 Processing Aid 2 2 2 Product of MB2
217.49 229.99 229.99 Stage 2 STAGE 3 Product of MB2 217.49 229.99
229.99 Stage 2 Sulfur Cross-linker 1.5 1.5 1.5 Santocure .RTM.
Accelerator 1.3 1.3 1.3 CBS Perkacit .RTM. Accelerator 1.5 1.5 1.5
DPG-grs TOTAL 221.79 234.29 234.29
TABLE-US-00010 TABLE 8 Phr of CE/ Pz level MB in Plasticizer Tg
before (g/100 g formu- Tg after Blends CE plasticizer Plasticizer
CE) lation plasticizer CE-MB1 CAB 133.degree. C. -- -- 10
133.degree. C. 381-2 CE-MB2 CAB 133.degree. C. EMN 168 25 12.5
95.degree. C. 381-2 CE-MB3 CAB 133.degree. C. PEG-300 25 12.5
70.degree. C. 381-2
TABLE-US-00011 TABLE 9 STAGE 1 STAGE 2 STAGE 3 Start Temperature
65.degree. C. 65.degree. C. 50.degree. C. Starting Rotor 65 65 60
Speed (RPM) Fill Factor 67% 64% 61% Mix Sequence Add elastomers Add
half of first master batch Add half of second master After 1
minute, add 2/3 silica + After 15 seconds, add other batch Si69
components and other half of first master batch After 2 minutes,
add 1/3 silica + After 1 minute, sweep After 15 seconds, add
sulfur, other components accelerator package, and After 3 minutes,
sweep After 1.5 minutes, adjust rotor other half of second master
speed to increase temperature to batch After 3.5 minutes, adjust
rotor between 140 and 145.degree. C. After 1 minute, sweep speed to
increase temperature to 160.degree. C. Dump Conditions Hold for 2
minutes at 160.degree. C. Hold for 4 minutes at 140 to 145.degree.
C. Hold for 2.5 minutes at 110.degree. C. Total Time 6.5 minutes
7.5 minutes 3.75 minutes
Example 5
[0178] Various performance properties of the elastomeric
compositions produced in Example 4 were tested. Descriptions of the
various analytical techniques used to measure performance are
provided below.
[0179] The break stress and break strain were measured as per ASTM
D412 using a Die C for specimen preparation. The specimen had a
width of 1 inch and a length of 4.5 inches. The speed of testing
was 20 inches/min and the gauge length was 63.5 mm (2.5 inch). The
samples were conditioned in the lab for 40 hours at 50%+/-5%
humidity and at 72.degree. F. (22.degree. C.).
[0180] The Mooney Viscosities were measured according to ASTM D
1646.
[0181] The Phillips Dispersion Rating was calculated by cutting the
samples with a razor blade and subsequently taking pictures at
30.times. magnification with an Olympus SZ60 Zoom Stereo Microscope
interfaced with a Paxcam Arc digital camera and a Hewlett Packard
4600 color printer. The pictures of the samples were then compared
to a Phillips standard dispersion rating chart having standards
ranging from 1 (bad) to 10 (excellent).
[0182] Mechanical Properties: modulus at 100% and 300% strains were
measured as per ASTM D412 using Die C for specimen preparation. The
speed of testing was 20 inches/min and the gauge length was 63.5 mm
(2.5 inch). The samples were conditioned in the lab for 40 hours at
50%+/-5 humidity and 72.degree. F. The width of specimen was 1
inch, and length was 4.5 inch.
[0183] Hardness: Shore A hardness was measured according to ASTM
D2240.
[0184] Temperature Sweep: A TA Instruments dynamic mechanical
analyzer was used to complete the temperature sweeps using tensile
geometry. Storage modulus (E'), loss modulus (E''), and tan delta
(=E''/E') were measured as a function of temperature from
-80.degree. C. to 120.degree. C. using 10 Hz frequency, 5% static,
and 0.2% dynamic strain.
[0185] Rebound Test: The rebound pendulum test was carried out as
per ASTM D7121-05.
[0186] Wear: Din abrasion testing was performed per ASTM 222.
[0187] The data shows that without the use of a plasticizer, the
cellulose ester did not disperse as well through the elastomer as
shown by the poor Phillips Dispersion data. Further, the Mooney
Viscosities of the compositions containing both cellulose ester and
plasticizer were lower than when plasticizer was not utilized. This
shows that in the presence of the plasticizer, cellulose esters
acted as a processing aid and lowered Mooney viscosity.
Furthermore, the break stress and wear was also improved over
compositions without plasticizer, presumably indicating that in
presence of the plasticizers, cellulose esters can disperse into
finer particles and improve the properties that are dependent on
particle size and/or surface area.
TABLE-US-00012 TABLE 10 Properties CAB-1 CAB-2 CAB-3 Uncured Rubber
Mooney viscosity 63.5 58.5 55.1 Cured Rubber Phillips Dispersion 1
4 4 Break stress, psi 2191 2240 2349 Break strain, % 386 387 366
Modulus(M100), psi 663 679 735 Modulus (M300), 1693 1723 1918 psi
Shore A Hardness 61 59 62 Tan Delta 0.degree. C. 0.306 0.292 0.313
Tan Delta 60.degree. C. 0.082 0.081 0.076 Rebound 0.degree. C., %
9.8 10.8 9.6 Rebound 60.degree. C., % 62.2 62.8 64.0 Wear, volume
loss 136 124 127 in mm.sup.3
* * * * *