Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2002-06-28
2004-04-13
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...
C521S134000, C521S149000, C521S150000
Reexamination Certificate
active
06720361
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a foamable thermoplastic clastomer composition and method of producing the same, more particularly to a foamable thermoplastic elastomer composition containing thermally expandable microcapsules and a method of producing the same.
2. Description of the Prior Art
Recently, resins have been foamed for improving their properties, e.g., heat insulation, sound insulation and shock absorption, and reducing their weight. The foamed resins are widely used for various purposes, e.g., gaskets for construction materials, floor materials, piping protection materials, shoe soles, door packings, sporting goods, grips, toys, vibration insulators, heat insulators, sound insulators and shock absorbers.
One method of producing the foamed resins includes a foaming agent in ethylene-&agr;-olefin-based copolymer rubber to produce a thermoplastic hollow resin, as disclosed by Japanese Patent Laid-open Publication No. S59-1541. The method of foaming the above resin uses a foaming agent, e.g., nitroso, azo or urea compound. Use of these foaming agents, however, causes several problems, e.g., unstable foamed conditions, uneven size of the cells, and difficulty in continuously producing formed articles of foamed resins.
Japanese Patent Laid-open Publication No. S59-196328 discloses a rubber composition for foaming, composed of rubber or rubber elastomer incorporated with microcapsules, wherein the capsule shell of a thermoplastic resin contains core material which can expand the shell when heated. Moreover, Japanese Patent Laid-open Publication No. H4-246440 discloses a rubber composition composed of a rubber-like polymer incorporated with heat-expandable microcapsules starting to expand at 120° C. or higher, wherein the capsule shell of an acrylonitrile copolymer contains a low-boiling point hydrocarbon. Even these methods which use heat-expandable microcapsules cannot stabilize the foamed conditions, and it is difficult to cause the resin to have uniformly sized cells that are continuously formed in the expanded article. Another problem is the forming method is limited to pressing, when a vulcanized rubber material is used.
It is an object of the present invention to provide a foamable thermoplastic elastomer composition which can be formed into a stable foamed article incorporated with heat-expandable microcapsules, in consideration of the above problems. It is another object of the present invention to provide a method of producing the same.
SUMMARY OF THE INVENTION
The inventors of the present invention have found, after having extensively studied to solve the above problems, that a foamable thermoplastic elastomer composition which can be formed into stable foamed articles can be obtained by incorporating a thermoplastic resin with a resin composition containing an olefin-based resin having a specific melting or softening point, heat-expandable microcapsules which expand at 120 to 300° C. and the volatile composition. In particular, the inventors have found that the stable elastomer composition for foamed articles is obtained by kneading the composition in two stages at a specific temperature or lower, thereby achieving the present invention.
The first aspect of the invention is a foamable thermoplastic elastomer composition which contains:
(a) 10 to 90 parts by weight of one of an olefin-based resin and rubber having a melting or softening point of 140° C. or lower;
(b) 9 to 85 parts by weight of heat-expandable microcapsules expanding at 120 to 300° C.; and
(c) 1 to 50 parts by weight of a volatile composition,
wherein the components (a) to (c) total 100 parts by weight.
The second aspect of the invention is a foamable thermoplastic elastomer composition which contains:
(a) 10 to 90 parts by weight of one of an olefin-based resin and rubber having a melting or softening point of 140° C. or lower;
(b) 9 to 85 parts by weight of heat-expandable microcapsules expanding at 120 to 300° C.;
(c) 1 to 50 parts by weight of a volatile composition; and
(d) 50 to 99 parts by weight of a thermoplastic resin, wherein the components (a) to (d) total 100 parts by weight.
The third aspect of the invention is the foamable thermoplastic elastomer composition of the first or second aspect, wherein said volatile composition (c) has a boiling point of 90 to 250° C., or evaporates at (0.5 g/1000 cm
2
)/hour or more at 100° C.
The fourth aspect of the invention is the foamable thermoplastic elastomer composition of the first or second aspect, wherein said volatile composition (c) is of at least one type selected from the group consisting of a hydrocarbon and oxygen-containing compound.
The fifth aspect of the invention is the foamable thermoplastic elastomer composition of the first or second aspect, wherein said volatile composition (c) is of at least one type selected from the group consisting of water and water-containing composition, and contained at 1 to 30 parts by weight per 100 parts by weight of the components (a) to (c) totaled.
The sixth aspect of the invention is a method of producing a foamable thermoplastic elastomer composition by kneading, at 140° C. or lower, (a) 10 to 90 parts by weight of one of an olefin-based resin and rubber having a melting or softening point of 140° C. or lower, (b) 9 to 85 parts by weight of heat-expandable microcapsules expanding at 120 to 300° C., and (c) 1 to 50 parts by weight of a volatile composition.
The seventh aspect of the invention is a method of producing a foamable thermoplastic elastomer composition, wherein the composition is produced in two stages, the first stage kneading, at 140° C. or lower, (a) 10 to 90 parts by weight of one of an olefin-based resin and rubber having a melting or softening point of 140° C. or lower, (b) 9 to 85 parts by weight of heat-expandable microcapsules expanding at 120 to 300° C., and (c) 1 to 50 parts by weight of a volatile composition, to produce the resin composition containing the components (a) to (c), and the second stage adding the resin composition containing the components (a) to (c) to (d) a thermoplastic resin, and kneading these components.
The eighth aspect of the invention is the method of the seventh aspect for producing a foamable thermoplastic elastomer composition, wherein the ratio of said resin composition containing the components (a) to (c)/thermoplastic resin (d) is any weight ratio from 1.0:99.0 to 50:50.
The ninth aspect of the invention is the method of the sixth or seventh aspect for producing a foamable thermoplastic elastomer composition, wherein said volatile composition (c) has a boiling point of 90 to 250° C., or evaporates at (0.5 g/1000 cm
2
)/hour or more at 100° C.
The tenth aspect of the invention is the method of the sixth or seventh aspect for producing a foamable thermoplastic elastomer composition, wherein said volatile composition (c) is of at least one type selected from the group consisting of a hydrocarbon and oxygen-containing compound.
The 11
th
aspect of the invention is the method of the sixth or seventh aspect for producing a foamable thermoplastic elastomer composition, wherein said volatile composition (c) is of at least one type selected from the group consisting of water and water-containing composition, and contained at 1 to 30 parts by weight per 100 parts by weight of the components (a) to (c) totaled.
The 12
th
aspect of the invention is the method of the sixth or seventh aspect for producing a foamable thermoplastic elastomer composition, wherein a kneader is used for kneading the components.
DETAILED DESCRIPTION OF THE INVENTION
The foamable thermoplastic elastomer composition of the present invention is described in more detail with respect to its components, method of production and purposes.
1. Components of the Expandable Thermoplastic Elastomer Composition
(1) Olefin-based Resin or Rubber Component (a)
The olefin-based resin or rubber component (a) for the present invention includes olefin-based copolymer rubber and amorphous polyolefin. The olefin-based resin or rubber has a melting o
Mizuno Hiroki
Tasaka Michihisa
Foelak Morton
Riken Technos Corp.
Westerman Hattori Daniels & Adrian LLP
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