Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2003-01-09
2004-07-27
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S059000, C521S060000, C521S079000, C521S081000, C525S240000
Reexamination Certificate
active
06767931
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to foamable polymer compositions comprising a1) a substantially random interpolymer produced from i) one or more &agr;-olefin monomers and ii) one or more vinyl or vinylidene aromatic monomers and/or one or more sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, and optionally iii) other polymerizable ethylenically unsaturated monomer(s), or a2) an interpolymer comprising polymerized units of ethylene and vinyl acetate or a3) a combination of the polymers a1) and a2) and a high molecular weight polysiloxane.
Foamable compositions comprising ethylene/vinyl acetate polymers are well known and widely used for making footwear, such as shoe soles. Substantially random interpolymers a1) and their use for producing foams are described in U.S. Pat. No. 5,460,818. From such polymers, foamed articles can be produced which are generally soft, flexible and resilient. They can also be hard, that means less resilient and less flexible, and exhibit high compression set. Accordingly, the above-mentioned interpolymers can be potentially used in many applications, such as tarps, coated fabrics, shoe soles, shoe stiffeners, and artificial leather, tires for bicycles, wheel chairs, and stroller wheels, and in wire and cable insulation and jacketing formed by general extrusion or by calendered sheets or films with and without fillers. Some of the shoe soles and wheels are produced via injection molding and cross-linking processes where usually ethylene/vinyl acetate polymers are hard to control since they tend to stick to molds and to expand unevenly.
For many of these applications, such as shoe soles, wheels and wire and cable insulation, it is important that the flexible articles also have a good surface abrasion resistance. In some applications like shoe soles, a high coefficient of friction (COF) is also desirable. An unduly low coefficient of friction increases the danger of slipping on the ground.
Accordingly, one object of the present invention is to improve the surface abrasion resistance of foams comprising the above-mentioned interpolymers. A preferred object of the present invention is to improve the surface abrasion resistance of such foams without decreasing their coefficient of friction.
SUMMARY OF THE INVENTION
One aspect of the present invention is a foamable polymer composition which comprises
a1) a substantially random interpolymer produced from i) one or more &agr;-olefin monomers and ii) one or more vinyl or vinylidene aromatic monomers and/or one or more sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, and optionally iii) other polymerizable ethylenically unsaturated monomer(s), or
a2) an interpolymer comprising polymerized units of ethylene and vinyl acetate or
a3) a combination of the polymers a1) and a2); and
b) a polydiorganosiloxane having a viscosity of at least one million centistoke at 25° C.; and
c) a foaming agent.
Another aspect of the present invention is a foam comprising
a1) a substantially random interpolymer produced from i) one or more &agr;-olefin monomers and ii) one or more vinyl or vinylidene aromatic monomers and/or one or more stenically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, and optionally iii) other polymerizable ethylenically unsaturated monomer(s), or
a2) an interpolymer comprising polymerized units of ethylene and vinyl acetate or
a3) a combination of the polymers a1) and a2); and
b) a polydiorganosiloxane having a viscosity of at least one million centistoke at 25° C.
Yet another aspect of the present invention is a process for producing a foam wherein the above-mentioned foamable polymer composition is exposed to an elevated temperature to release blowing agent and to form a foam structure.
Yet another aspect of the present invention is a fabricated article comprising the above-mentioned foam.
Yet another aspect of the present invention is a method of improving the abrasion resistance of a foam comprising:
a1) a substantially random interpolymer produced from i) one or more &agr;-olefin monomers and ii) one or more vinyl or vinylidene aromatic monomers and/or one or more sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, and optionally iii) other polymerizable ethylenically unsaturated monomer(s), or
a2) an interpolymer comprising polymerized units of ethylene and vinyl acetate or
a3) a combination of the polymers a1) and a2); which method comprises the step of incorporating into said foam an effective amount of a polydiorganosiloxane having a viscosity of at least one million centistoke at 25° C.
DETAILED DESCRIPTION OF THE INVENTION
The term “comprising” as used herein means “including”. The term “comprising” is not to be understood to mean “consisting of”.
The term “interpolymer” is used herein to indicate a polymer wherein at least two different monomers are polymerized to make the interpolymer.
The term “substantially random” in the substantially random interpolymer resulting from polymerizing i) one or more &agr;-olefin monomers and ii) one or more vinyl or vinylidene aromatic monomers and/or one or more sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, and optionally iii) other polymerizable ethylenically unsaturated monomer(s) as used herein generally means that the distribution of the monomers of said interpolymer can be described by the Bernoulli statistical model or by a first or second order Markovian statistical model, as described by J. C. Randall in POLYMER SEQUENCE DETERMINATION, Carbon-13 NMR Method, Academic Press New York, 1977, pp. 71-78. Preferably, the substantially random interpolymer resulting from polymerizing one or more &agr;-olefin monomers and one or more vinyl or vinylidene aromatic monomers, and optionally other polymerizable ethylenically unsaturated monomer(s), does not contain more than 15 percent of the total amount of vinyl or vinylidene aromatic monomer in blocks of vinyl or vinylidene aromatic monomer of more than 3 units. More preferably, the interpolymer is not characterized by a high degree of either isotacticity or syndiotacticity. This means that in the carbon-13 NMR spectrum of the substantially random interpolymer the peak areas corresponding to the main chain methylene and methine carbons representing either meso diad sequences or racemic diad sequences should not exceed 75 percent of the total peak area of the main chain methylene and methine carbons. By the subsequently used term “substantially random interpolymer” is meant a substantially random interpolymer produced from the above-mentioned monomers.
Suitable &agr;-olefin monomers which are useful for preparing the substantially random interpolymer include, for example, &agr;-olefin monomers containing from 2 to about 20, preferably from 2 to about 12, more preferably from 2 to about 8 carbon atoms. Particularly suitable are ethylene, propylene, butene-1,4-methyl-1-pentene, hexene-1 or octene-1 or ethylene in combination with one or more of propylene, butene-1,4-methyl-1-pentene, hexene-1 or octene-1. Most preferred are ethylene or a combination of ethylene with C
3-8
-&agr;-olefins. These &agr;-olefins do not contain an aromatic moiety.
Optional other polymerizable ethylenically unsaturated monomer(s) include strained ring olefins such as norbornene and C
1-10
alkyl or C
6-10
aryl substituted norbornenes, with an exemplary interpolymer being ethylene/styrene
orbornene.
Suitable vinyl or vinylidene aromatic monomers which can be employed to prepare the substantially random interpolymer include, for example, those represented by the following Formula I
wherein R
1
is selected from the group of radicals consisting of hydrogen and alkyl radicals containing from 1 to about 4 carbon atoms, preferably hydrogen or methyl; each R
2
is independently selected from the group of radicals consisting of hydrogen and alkyl radicals containing from 1 to about 4 carbon atoms, preferably hydrogen or methyl; Ar is a phenyl group or a phenyl group substituted with from 1 to
Batistini Antonio
Kjellqvist Jerker B. L.
Martinez Felipe
Wevers Ronald
Dow Global Technologies Inc.
Foelak Morton
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