JP2001026663A - Vibration-damping resin foam and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide vibration-damping resin foams which excel in elongation, flexibility, weatherability, and water resistance, and a process for producing the same. SOLUTION: Vibration-damping resin foams have, as the base material, a mixture of a triblock copolymer in which a polystyrene is bonded to a vinyl/ polyisoprene and a copolymer of ethylene and a 3-18C α-olefin. Further, the base material is a mixture of 50-95 pts.wt. triblock copolymer in which a polystyrene is bonded to a vinyl/polyisoprene and 50-5 pts.wt. copolymer of ethylene and a 3-18C α-olefin. A process for producing vibration-damping resin foams comprises adding a blowing agent and a crosslinking agent to a mixture of a triblock copolymer in which a polystyrene is bonded to a vinyl/polyisoprene with a copolymer resin of ethylene and a 3-18C α-olefin, kneading them, filling the resulting mixture into a closed mold, heating it under pressure, and then expanding it by releasing the pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock-absorbing vibration-damping resin foam used for flooring materials, athletic shoes, sports equipment pads, and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Vibration damping foams are soft and have a large vibration damping ability, so that sporting goods such as athletic shoes and pads, flooring materials, Sunday goods, etc. are used for shock absorption and vibration absorption. Used to The vibration damping property of the polymer is based on the phenomenon that the polymer exhibits a viscoelastic behavior near the glass transition temperature or a secondary transition temperature lower than the glass transition temperature, the internal friction is large, and the vibration damping ability is large. Conventionally, a polyurethane foam damping material has been used. For example, a damping material used for a ceiling, a floor, etc. having both a damping property and a sound absorbing property by using a specific amount of a foam stabilizer when producing a flexible polyurethane foam. (Japanese Patent Publication No. 5-8209), a soundproofing / damping foam obtained by foaming an organic polyisocyanate and a specific polyol in the presence of a foaming agent, a catalyst, a foam stabilizer and a fluid having a plasticizing effect. (Tokuhei 7-25
No. 863) has been proposed. These vibration damping materials of urethane foam have excellent vibration damping properties, but have disadvantages in that they are inferior in weather resistance and water resistance.

Further, rubber-based damping foams have been proposed. For example, 1.2 is excellent in damping performance, has a slow restoration speed, is excellent in shock absorption, and has good compatibility with a thermoplastic resin.
-Method for producing polybutadiene foam (JP-A-7-621)
No. 30), a vibration-damping resin foam obtained by crosslinking and foaming a molded article of a mixture of 1,2-polybutadiene having damping properties and a vinyl bond-polyisoprene-polystyrene block copolymer having damping properties ( Japanese Patent Application Laid-Open No. 8-208869) has been proposed.

[0004]

However, the above-mentioned prior art 1,2-polybutadiene-based foam is not suitable for 1,2-polybutadiene foam.
Polybutadiene has double bond carbon of vinyl group in the side chain, so it is easy to crosslink by bonding between side chains or between side chain and main chain, thereby hardening rapidly, resulting in insufficient elongation and flexibility That was a drawback. Accordingly, it is an object of the present invention to provide a vibration-damping resin foam excellent in weather resistance, water resistance, elongation and flexibility, and a method for producing the same, which overcomes the drawbacks of the prior art.

[0005]

According to the present invention, in order to achieve the above object, a vibration damping resin foam of the present invention comprises a triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded, And a copolymer of α-olefin having 3 to 18 carbon atoms by heating and foaming to obtain a vibration-damping resin foam. In the vibration damping resin foam of the present invention, the triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded is 5%.
0 to 95 parts by weight is preferable, and ethylene and carbon number 3 to 18 are preferable.
Is preferably 50 to 5 parts by weight. When the amount of the triblock copolymer is less than 50 parts by weight, the vibration damping property is insufficient, and when the amount exceeds 95 parts by weight, the kneading operation is difficult, and the flexibility inherent in metallocene-based polyethylene is lacking. The method for producing a vibration-damping resin foam of the present invention comprises foaming a mixture of a triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded, and a copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms. It is characterized in that an agent and a crosslinking agent are added, kneaded, filled in a closed mold, heated under pressure and then depressurized to foam. In the production method of the present invention, for the same reason as described above, the triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded is 5%.
The amount is preferably from 0 to 95 parts by weight, and the copolymer with an α-olefin having 3 to 18 carbon atoms is preferably from 50 to 5 parts by weight.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The triblock copolymer comprising polystyrene and vinyl-polyisoprene used in the present invention has a glass transition temperature (Tg or ta) at room temperature.
nδ), and exhibits high damping performance in this temperature range. The copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms used in the present invention acts as a binder for the triblock copolymer, imparts flexibility, and imparts a non-slip effect. 0.
By using a resin of 86 to 0.90 g / cm ³ , the non-slip property and the recovery property are excellent. In the present invention, a copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms is obtained by using a metallocene compound containing a tetravalent transition metal as a polymerization catalyst. As the metallocene compound, generally, a transition metal is used. A compound sandwiched between π-electron unsaturated compounds, and a bis (cyclopentadienyl) metal complex is a typical example. In the present invention, as the α-olefin, for example, propylene, 1-butene, 1-
Pentene, 1-hexene, 4-methyl-1-pentene,
And 1-octene.

Hereinafter, preferred embodiments of the method for producing a vibration-damping resin foam according to the present invention will be specifically described. First, a foaming agent, a cross-linking agent, and, if necessary, a foaming agent are added to a mixture of a triblock copolymer in which polystyrene and vinyl-polyisoprene are combined and a copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms. Auxiliaries, fillers, pigments and the like are added, and the mixture is kneaded with a heated mixing roll, pressure kneader, extruder or the like. The cross-linking agent referred to in the present invention is a resin having a decomposition temperature at least equal to the flow start temperature of the resin, and is decomposed by heating to generate free radicals to form cross-links between or within the molecules. An organic peroxide which is a radical generator to be generated, such as dicumyl peroxide, 1,
1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-
Ditertiary butylperoxyhexane, 2,5-dimethyl-2,5-ditertiarybutylperoxyhexyne, α, α-ditertiarybutylperoxyisopropylbenzene, tertiarybutylperoxyketone, tertiarybutylperoxybenzoate However, the most suitable organic peroxide must be selected depending on the resin used at that time.

The blowing agent which can be used in the present invention is a chemical blowing agent having a decomposition temperature higher than the melting temperature of the polyethylene resin, such as azodicarbonamide, an azo compound,
Barium azodicarboxylate and the like: nitroso compounds such as dinitrosopentamethylenetetramine and trinitrotrimethyltriamine; hydrazide compounds such as p,
p'-oxybisbenzenesulfonyl hydrazide and the like;
There are sulfonyl semicarbazide compounds such as p, p'-oxybisbenzenesulfonyl semicarbazide and toluenesulfonyl semicarbazide. In the present invention, a foaming aid can be added according to the type of the foaming agent. As a foaming aid, a compound containing urea as a main component,
Metal oxides such as zinc oxide and lead oxide; compounds containing salicylic acid, stearic acid and the like as main components, that is, higher fatty acids and metal compounds of higher fatty acids. In the present invention, for the purpose of improving the physical properties of the composition to be used or lowering the price, a compounding agent (filler) that does not significantly affect the cross-linking, such as zinc oxide, titanium oxide, calcium oxide, magnesium oxide, oxide Metal oxides such as silicon,
Carbonates such as magnesium carbonate and calcium carbonate, or fibrous materials such as pulp, or various dyes, pigments, fluorescent materials, and other commonly used rubber compounding agents can be added as necessary.

The foamable crosslinkable composition obtained by kneading as described above is charged into a closed mold, and is pressurized with a press at 130 to 170 ° C., preferably 130 to 170 ° C., depending on the type of the resin and the crosslinking agent. At 140 to 160 ° C., preferably 10 to 5
After heating for 0 minutes, the pressure is removed to obtain a damping resin foam. Alternatively, the foaming agent is partially decomposed by heating in a closed mold under pressure and then depressurized to obtain an intermediate foam, and the obtained intermediate is subjected to normal pressure, for example, in a foaming machine by jacket-type heating. A conventionally known foaming method such as a two-stage foaming method for obtaining a final foam by heating or heating in a heat medium bath can be applied. The heating temperature under normal pressure ranges from 140 to 21 depending on the type of resin used.
The temperature is set to 0 ° C., preferably 150 to 190 ° C.
The heating time is preferably 10 to 90 minutes, more preferably 20 to 70 minutes. The resilience of the damping foam obtained in the present invention is measured by a test method specified in JIS K6401. Specifically, using a 5 / 8-in side-by-side sphere, it is expressed as a value (percentage) obtained by dividing the rebound distance when naturally dropped from a height of 460 mm by the fall distance. In the present invention, an expansion ratio of 3 to 15 produced by a pressurized single-stage foaming method is used.
A double damping resin foam has excellent damping properties and is particularly useful.

[0010]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples. Example 1 A triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded (trade name “Hybler HVS-3”,
Styrene content 20%, vinyl bond content 55%, glass transition temperature -19 ° C, 90 parts by weight (manufactured by Kuraray Co., Ltd.), polyethylene resin polymerized using a metallocene catalyst (trade name “Kernel KS240”, MFR2) .2g / 1
0 minutes, density 0.88 g / cm3, manufactured by Nippon Polychem Co., Ltd.) 10 parts by weight, azodicarbonamide 3.5 parts by weight,
A composition comprising 1.1 parts by weight of dicumyl peroxide, 2.0 parts by weight of zinc white, and 0.5 parts by weight of zinc stearate is kneaded with a mixing roll at 85 ° C., and is pressed in a press heated to 155 ° C. Was filled in a mold (195 x 380 x 28 mm), heated under pressure for 35 minutes, and then depressurized to obtain a vibration-damping resin foam. The obtained foam had an apparent density of 0.098 g / cm3 and an elastic modulus of 22.4%.
It was excellent in vibration damping properties and had flexibility peculiar to metallocene-based polyethylene.

Example 2 Example 1 was repeated except that the triblock copolymer in which polystyrene and vinyl-polyisoprene were combined was changed to 80 parts by weight and 20 parts by weight of a polyethylene resin polymerized using a metallocene catalyst. A vibration damping resin foam was obtained under the same composition and the same foaming conditions as in Example 1. The resulting foam had an apparent density of 0.102 g / cm3 and an elastic modulus of 2
It was 5.6%, excellent in vibration damping properties, and had flexibility unique to metallocene-based polyethylene.

Comparative Example 1 In Example 1, 40 parts by weight of a triblock copolymer in which polystyrene and vinyl-polyisoprene were combined, and 60 parts of polyethylene polymerized using a metallocene catalyst were used.
A foam was obtained with the same composition and the same conditions as in Example 2 except that the amount was changed to parts by weight. The resulting foam had an apparent density of 0.
It was 096 g / cm3 and had an elastic modulus of 42.2%.

Example 3 Example 1 was repeated except that the triblock copolymer in which polystyrene and vinyl-polyisoprene were combined was changed to 70 parts by weight and 30 parts by weight of a polyethylene resin polymerized using a metallocene catalyst. A vibration damping resin foam was obtained under the same composition and the same foaming conditions as in Example 1. The obtained foam had an apparent density of 0.098 g / cm3 and an elastic modulus of 2
It was 8.8%, excellent in vibration damping properties, and had flexibility unique to metallocene-based polyethylene.

[0014]

[Table 1]

[0015]

As described above, according to the present invention, a triblock copolymer in which polystyrene and vinyl-polyisoprene are combined and a polyethylene resin polymerized using a metallocene catalyst are used in combination. It has a glass transition temperature (absorption of Tg or tan δ) in the room temperature range, exhibits high vibration damping performance in this temperature range, and has the flexibility and texture unique to metallocene polyethylene. It is excellent in vibration damping property, elongation, flexibility, weather resistance, water resistance and sound insulation, and is useful for sports equipment such as athletic shoes, flooring materials and the like.

Continued on the front page F term (reference) 4F074 AA13B AA17A AA18B BA13 BA15 BA16 BA17 BA18 BA19 BA29 BB02 CA22 CA25 CA30 CC03X CC04X CC04Y CC06X CC22X CC32X CC32Y CC34X DA02 DA36 DA40 DA58 4J002 BB05X BB01 00

Claims (4)

[Claims] 1. A foam made of a vibration-damping resin having a base material of a mixture of a triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded, and a copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms. body. 2. A base material comprising 50 to 95 parts by weight of a triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded and 50 to 5 parts by weight of a copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms. The vibration damping resin foam according to claim 1, which is a mixture with 3. A foaming agent and a crosslinking agent are added to a mixture of a triblock copolymer in which polystyrene and vinyl-polyisoprene are combined, and a copolymer resin of ethylene and an α-olefin having 3 to 18 carbon atoms, A method for producing a vibration-damping resin foam which is kneaded, filled in a closed mold, heated under pressure, and then decompressed and foamed. 4. The mixture is a triblock copolymer of polystyrene and vinyl-polyisoprene 50 to 95.
A mixture of parts by weight and 50 to 5 parts by weight of a copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms.
The method for producing a vibration-damping resin foam according to the above.