Foamable composition, process for producing the same and foam

Abstract

The present invention provides a foam which maintains high hardness while being lightweight and has excellent peel strength and permanent compression set, and a foamable composition used to obtain the aforementioned foam. A foamable composition comprising (A) an olefin-based copolymer; (B) a copolymer that is (B-I) and/or (B-II) described below, (B-I) a vinyl aromatic-based copolymer comprising a vinyl aromatic compound and a conjugated diene, and/or a vinyl aromatic-based copolymer comprising a vinyl aromatic compound and alkylene, (B-II) an ethylene-based copolymer having an unsaturated group; (C) an inorganic filler; (D) an organic silane coupling agent; and (E) a foaming agent; wherein a mass ratio of the component (A) to the component (B), (A/B), is from 5/95 to 100/0; an amount of the component (C) is from 0.5 to 35 mass parts, and an amount of the component (E) is from 0.1 to 20 mass parts, based on 100 mass parts of a total amount of the components (A) and (B); and an amount of the component (D) is from 0.1 to 50 mass parts, based on 100 mass parts of the component (C).

Claims

1. A foam obtained by foaming a composition comprising: (A) an olefin-based copolymer; (B-I) a hydrogenated vinyl aromatic-based block copolymer comprising (i) a conjugated diene monomer unit and (ii) a polymer block mainly containing at least one vinyl aromatic compound, wherein the amount of the conjugated diene monomer unit is from 14 to 50 mass % of the hydrogenated vinyl aromatic-based block copolymer by being hydrogenated after copolymerization, and the amount of the polymer block mainly containing at least one vinyl aromatic compound in the component (B-I) is from 37 mass % to 100 mass % of the total amount of the vinyl aromatic monomer units in the component (B-I); (C) an inorganic filler; (D) an organic silane coupling agent; (E) a foaming agent; and (F) a crosslinking agent, wherein a mass ratio of the component (A) to the component (B-I), (A/B-I), is from 5/95 to 98/2; an amount of the component (C) is from 0.5 to 35 mass parts, and an amount of the component (E) is from 0.1 to 20 mass parts, based on 100 mass parts of a total amount of the components (A) and (B-I); an amount of the component (D) is from 0.1 to 50 mass parts, based on 100 mass parts of the component (C); and the foam has a specific gravity that is 0.102 or more and 0.149 or less.

2. The foam according to claim 1, wherein the component (A) is an ethylene-based copolymer.

3. The foam according to claim 1, wherein the component (B-I) is a copolymer having a functional group in a molecular chain thereof.

4. The foam according to claim 1, wherein the component (C) has a mean dispersed particle diameter from 0.01 to 4 m.

5. The foam according to claim 1, wherein the component (D) is an organic silane coupling agent having a group exhibiting affinity for or binding ability to the component (A) and/or the component (B-I), and further a surface of the component (C).

6. The foam according to claim 1, wherein the component (D) is a polysulfide silane coupling agent.

7. The foam according to claim 1, wherein the vinyl aromatic-based copolymer of the component (B-I) has a tan peak within a range of more than 0 C. and 30 C. or less and a tan value at 15 C. of 0.4 or more, as determined by dynamic viscoelasticity measurement (1 Hz).

8. The foam according to claim 1, wherein the vinyl aromatic-based copolymer of the component (B-I) has a tan peak of 0 C. or less, as determined by dynamic viscoelasticity measurement (1 Hz).

9. The foam according to claim 1, further comprising from 0.1 to 20 mass parts of (F) the crosslinking agent, based on 100 mass parts of the total amount of the components (A) and (B-I).

10. A process for producing the foam of claim 1 comprising the steps of: (1) producing the composition comprising previously melt-kneading, at a first stage, at least (B-I) a vinyl aromatic-based block copolymer comprising a vinyl aromatic monomer unit and a conjugated diene monomer unit, (C) an inorganic filler, and (D) an organic silane coupling agent, at a temperature of 120 C. or more to obtain a master batch; and melt-kneading, at a second stage, the master batch, (A) an olefin-based copolymer, (E) a foaming agent, and/or (F) a crosslinking agent, and (2) foaming the composition to produce the foam.

11. A process for producing the foam of claim 1 comprising the steps of: (1) producing the composition comprising previously melt-kneading, at a first stage, at least (A) an olefin-based copolymer, (B-I) a vinyl aromatic-based block copolymer comprising a vinyl aromatic monomer unit and a conjugated diene monomer unit, (C) an inorganic filler, and (D) an organic silane coupling agent, at a temperature of 120 C. or more to obtain a master batch; and melt-kneading, at a second stage, the master batch, (E) a foaming agent, and as required, (F) a crosslinking agent, and (2) foaming the composition to produce the foam.

12. The foam according to claim 1, wherein the foam has a hardness (Shore C) from 15 to 70.

13. The foam according to claim 1, which has a hardness (Shore C) from 45 to 60, and a value of peel strength/specific gravity of 18 or more.

14. A footwear comprising the foam according to claim 1 or 12.

15. A building material comprising the foam according to claim 1 or 12.

16. An automobile member comprising the foam according to claim 1 or 12.

17. The foam according to claim 1, further comprising (B-II) an ethylene-based copolymer having an unsaturated group.

18. The foam according to claim 17, wherein a mass ratio of the component (B-I) to the component (B-II), (B-I/B-II), is 60/40 or more.

19. The foam according to claim 1, further comprising a second vinyl aromatic-based block copolymer comprising a vinyl aromatic monomer unit and an alkylene monomer unit.

20. The foam according to claim 1, wherein the plurality of polymer blocks comprise styrene.

21. The foam according to claim 1, wherein the component (A) is selected from the group consisting of an ethylene-vinyl acetate copolymer; a copolymer of three or more compounds that is obtained from ethylene and two or more compounds other than ethylene; and an ethylene--olefin copolymer of ethylene and -olefin containing 4 to 10 carbon atoms.

22. The foam according to claim 1, wherein the component (B-I) comprises from 5 to 62 mass % of the vinyl aromatic monomer unit.

23. The foam according to claim 1, wherein the composition excludes silica.

24. The foam according to claim 1, wherein the component (B-I) comprises a plurality of polymer blocks each consisting of vinyl aromatic monomer units.

25. The foam according to claim 1, wherein the component (A) is ethylene-1-butene copolymer.

26. The foam according to claim 1, wherein the component (B-I) excludes a functional group.

27. The foam according to claim 1, wherein the foaming agent is a thermally decomposable foaming agent.

28. The foam according to claim 1, wherein the inorganic filler comprises at least one filler selected from the group consisting of talc, calcium carbonate, calcium silicate, hydrotalcite, kaoline, diatomaceous earth, graphite, calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, calcium sulfate, barium sulfate, magnesium oxide, zinc oxide, and titanium oxide.

Description

EXAMPLES

(1) The present invention will be described in detail below, referring to specific examples and comparative examples; however, the present invention is not limited to examples below.

(2) In examples and comparative examples, vinyl aromatic-based copolymers were prepared and crosslinked foams were prepared according to the methods described below, and their physical properties were evaluated. The properties of each vinyl aromatic-based copolymer and the physical properties of each crosslinked foam were measured as below.

(3) [Measurement of Properties of Vinyl Aromatic-Based Copolymer]

(4) ((1) Styrene content, vinyl bond content in conjugated diene, hydrogenation rate of unsaturated bond based on conjugated diene compound, amounts of vinyl aromatic monomer unit, 1,4-bond unit and 1,2-bond unit in butadiene, ethylene unit, or butylene unit)

(5) These values were measured by nuclear magnetic resonance spectral analysis (NMR).

(6) JNM-LA400 (trade name, manufactured by JEOL Ltd.) was used as a measurement apparatus, and deuterated chloroform was used as a solvent. The concentration of a sample was set at 50 mg/mL, and the observing frequency was set at 400 MHz. TMS (tetramethylsilane) was used as a chemical shift standard, and the measurement was carried out under the following conditions: a pulse delay: 2.904 sec; the number of scanning operations: 64 times, a pulse width: 45; and a measurement temperature: 26 C.

(7) ((2) Measurement of Polystyrene Block Content)

(8) The content of a polystyrene block was measured according to the osmium tetroxide method described in I. M. Kolthoff, et al., J. Polym. Sci. 1, 429 (1946), using a vinyl aromatic-based copolymer before hydrogenation. A 0.1 g/125 mL tertiary butanol solution of osmic acid solution was used to decompose the vinyl aromatic-based copolymer.

(9) ((3) Measurement of Weight Average Molecular Weight and Molecular Weight Distribution)

(10) The weight average molecular weight and molecular weight distribution of a vinyl aromatic-based copolymer were obtained relative to the molecular weight in terms of polystyrene, by gel permeation chromatography (GPC) measurement (apparatus: LC-10 (trade name, manufactured by Shimadzu Corporation); column: two columns of TSKgeIGMHXL (4.6 mm ID30 cm); solvent: tetrahydrofuran (flow rate: 1.0 mL/min), column temperature: 40 C.), using commercially available standard polystyrene. Moreover, the molecular weight distribution was obtained in the form of the ratio between the obtained weight average molecular weight and number average molecular weight.

(11) ((4) Content of Modified Vinyl Aromatic-based Copolymer)

(12) The characteristic of a modified component to be adsorbed on a GPC column containing silica-based gel as a filler was applied. As for a sample solution containing a modified vinyl aromatic-based copolymer and a low-molecular-weight internal standard polystyrene, the ratio of the modified vinyl aromatic-based copolymer to the standard polystyrene in the chromatogram measured in (3) above was compared with the ratio of the modified vinyl aromatic-based copolymer to standard polystyrene in a chromatogram measured by a silica-based column GPC [column: Zorbax, manufactured by Du Pont Kabushiki Kaisha; solvent: tetrahydrofuran (flow rate: 0.5 mL/min); and column oven temperature: 40 C.], and the obtained difference was used for measuring the amount of the modified vinyl aromatic-based copolymer adsorbed on the silica column. The ratio of an unmodified vinyl aromatic-based copolymer corresponds to the ratio of the vinyl aromatic-based copolymer that has not been adsorbed on the silica column.

(13) The ratio of the modified vinyl aromatic copolymer was calculated based on these results.

(14) ((5) Measurement of Dynamic Viscoelasticity Data)

(15) The after-mentioned vinyl aromatic-based copolymers (B1 to B4) were each cut into a size of 10 mm wide and 35 mm long, so as to prepare test pieces to be measured. The thus prepared test pieces were each set into a twisted type geometry of an apparatus, ARES (trade name, manufactured by TA InstrumentsWaters LLC), and the dynamic viscoelasticity data of each test piece was measured under the following conditions: effective measured length: 25 mm; strain: 0.5%; frequency: 1 Hz; and a temperature rise rate from 50 C. to 50 C. of 3 C./min. Thereafter, the tan value at 15 C. was obtained.

(16) The peak temperature of tan was obtained by automatic measurement using RSIOrchestrator (trade name, manufactured by TA InstrumentsWaters LLC).

(17) [Measurement of Physical Properties of Crosslinked Foam]

(18) ((1) Specific Gravity)

(19) Each crosslinked foam was punched to form a test piece in the form of a disc having a diameter of 1.4 cm and a thickness of 1 cm, and its specific gravity was measured using an electronic gravimeter (MD-2005, manufactured by Alfa Mirage Co., Ltd.).

(20) ((2) Hardness)

(21) The hardness (Shore C) of each crosslinked foam was measured using an Asker C durometer (CL-150 Shore C, manufactured by Kobunshi Keiki, Co., Ltd.), and momentary values were read. An average value of five points (arithmetic average) was then taken as the hardness.

(22) ((3) Permanent Compression Set)

(23) Each crosslinked foam was adjusted to a size of 1 cm (thickness); it was compressed to 50% of its thickness in accordance with JIS-K6262, and maintained at 23 C. for 22 hours; the pressure was subsequently released, and the thickness after 30 minutes was measured to evaluate the magnitude of the residual strain.

(24) ((4) Peel Strength)

(25) A crosslinked foam was made into a 2 cm10 cm1 cm (thickness) test piece, and the test piece was provided with a 2 cm cut in the center; the test piece was then placed between chucks with a distance of about 4 cm, and measurement was conducted at 100 mm/min, using a universal tensile and compression testing machine (TG-1kN, manufactured by NMB Minebea). The peel strength was calculated according to the following equation:
Peel strength=Measurement maximum peel strength/2 (kgf/cm)
((5) Tear Strength)

(26) A crosslinked foam was adjusted to a size of 1 cm (thickness)an angle shape (no cut), and it was then placed between chucks with a distance of about 6 cm in accordance with JIS-K6252. Thereafter, measurement was conducted at 500 mm/min, using a universal tensile and compression testing machine (TG-5kN, manufactured by NMB Minebea). The tear strength was calculated according to the following equation:
Tear strength=Measurement maximum tear strength (kgf/cm)
((6) Tensile Strength and Tensile Elongation)

(27) A crosslinked foam was adjusted to a size of 1 cm (thickness)a dumbbell No. 1 shape, and it was then placed between chucks with a distance of about 6 cm in accordance with JIS-K6251. Thereafter, measurement was conducted at 500 mm/min, using a universal tensile and compression testing machine (TG-5kN, manufactured by NMB Minebea).
Tensile strength=Measurement maximum tensile strength/Initial cross section area (kgf/cm.sup.2)
Tensile elongation=Test piece elongation at break (cm)/2cm Initial gauge length100
((7) Impact Resilience)

(28) A crosslinked foam was adjusted to a thickness of 1 cm, and the impact resilience was then measured in accordance with JIS-K6255; a 15 g iron ball was dropped from a height of 40 cm (=L.sub.0), and the rebound height of the iron ball (=L) was measured at 23 C. The impact resilience was determined using the following equation:
Impact resilience(%)=L/L.sub.0100
((8) Adhesive Strength)

(29) A crosslinked foam and a vulcanized rubber were each cut into a test piece with a size of 2 cm10 cm1 cm (thickness), and they were then prepared by the following methods. Thereafter, the adhesive strength of the crosslinked foam and that of the vulcanized rubber were measured.

(30) <(1) Preparation of Crosslinked Foam>

(31) 1. The surface of a crosslinked foam was washed with water, and was then dried in an oven at 50 C. for 10 minutes. 2. An aqueous UV primer P-6-2 (DONGSUNG NSC LTD.) was applied to the surface, and the resultant surface was then dried in an oven at 50 C. for 2.5 minutes. 3. The surface was irradiated with UV (0.56 J/cm.sup.2). 4. An aqueous adhesive WO1 (DONGSUNG NSC LTD.) was applied to the surface, and the surface was then hot-air dried at 55 C. for 1.5 minutes.
<(2) Preparation of Vulcanized Rubber> 1. The surface of a vulcanized rubber was washed with water, and was then dried in an oven at 50 C. for 30 minutes. 2. An aqueous primer PR-505 (DONGSUNG NSC LTD.) was applied to the surface, and the resultant surface was then hot-air dried at 55 C. for 1.5 minutes. 3. An aqueous adhesive WO1 (DONGSUNG NSC LTD.) was applied to the surface, and the surface was then hot-air dried at 55 C. for 1.5 minutes.
<(3) Measurement of Adhesive Strength by Adhesive Integration of Crosslinked Foam and Vulcanized Rubber>

(32) The two substrates, the surface of each of which had been coated with an aqueous adhesive WO1 (DONGSUNG NSC LTD.), were pressed at 78.4 Pa (8 kg/cm.sup.2) for 30 minutes, so that they were integrated. Thereafter, the adhesive strength was measured at 100 mm/min using a universal tensile and compression testing machine (TG-5kN, manufactured by NMB Minebea).

(33) ((9) Balance between Lightness and Peel Strength)

(34) The ratio peel strength/specific gravity between the specific gravity of the foam and the peel strength thereof was calculated. It was determined that, the greater this value, a better balance could be obtained between the lightless of the foam and the peel strength thereof.

(35) [Raw Materials Used]

(36) The (A) olefin-based copolymers, (B) vinyl aromatic-based copolymers, (C) inorganic fillers, (D) organic silane coupling agents, (E) foaming agents, and (F) crosslinking agents, which were used in the after-mentioned Examples and Comparative Examples, are described below.

(37) ((A) Olefin-Based Copolymer)

(38) <A1>

(39) An ethylene-1-butene copolymer (manufactured by Mitsui Chemicals, Inc., trade name TAFMER DF110)

(40) Hardness (Shore A): 96

(41) <A2>

(42) An ethylene-1-butene copolymer (manufactured by Mitsui Chemicals, Inc., trade name TAFMER DF810)

(43) Hardness (Shore A): 87

(44) <A3>

(45) An ethylene-vinyl acetate copolymer (manufactured by Du Pont-Mitsui Polychemicals, Co., Ltd., trade name EVAFLEX EV460)

(46) Hardness (Shore A): 90

(47) ((B) Copolymer)

(48) [(B-I) Vinyl Aromatic-Based Copolymer]

(49) (Preparation of Hydrogenation Catalyst)

(50) A hydrogenation catalyst used in the hydrogenation reaction of a vinyl aromatic-based copolymer was prepared by the following method.

(51) Into a nitrogen-purged reactor, 1 liter of dried and purified cyclohexane was placed, and 100 mmol of bis(5-cyclopentadienyl)titanium dichloride was then added to the reactor. Thereafter, while fully stirring, a n-hexane solution containing 200 mmol of trimethyl aluminum was added to the reactor. The obtained mixture was reacted at room temperature for approximately 3 days.

(52) The following <B1> to <B4> were prepared as (B-I) vinyl aromatic-based copolymers.

(53) <B1>

(54) Using a stirrer with an internal volume of 10 liters and a jacketed tank-type reactor, a vinyl aromatic-based copolymer was prepared by the following method.

(55) A predetermined amount of cyclohexane was placed into the reactor, and the temperature was then adjusted to 70 C. Thereafter, n-butyllithium was added to the reactor from the bottom thereof, so that the amount of the n-butyllithium could be 0.16 mass parts based on the total mass of all monomers (the total amount of a butadiene monomer and a styrene monomer supplied to the reactor). Moreover, a cyclohexane solution of N,N,N,N-tetramethylethylenediamine was added to the reactor, so that the amount of the N,N,N,N-tetramethylethylenediamine could be 0.35 moles based on 1 mole of the n-butyllithium. Thereafter, a cyclohexane solution containing 15 mass parts of styrene at the first step (monomer concentration: 24 mass %) was supplied as a monomer to the reactor for approximately 10 minutes, and the temperature in the reactor was then adjusted to approximately 70 C.

(56) After stoppage of the supply, the reaction was carried out for 15 minutes, while adjusting the temperature in the reactor to 70 C.

(57) Subsequently, a cyclohexane solution containing 70 mass parts of butadiene at the second step (monomer concentration: 24 mass %) was continuously supplied at a constant rate to the reactor over 60 minutes, and during this operation, the temperature in the reactor was adjusted to 70 C. After stoppage of the supply, the reaction was carried out for 10 minutes, while adjusting the temperature in the reactor to 70 C.

(58) Thereafter, a cyclohexane solution containing 15 mass parts of styrene at the third step (monomer concentration: 24 mass %) was supplied to the reactor for approximately 10 minutes, and the temperature in the reactor was then adjusted to approximately 70 C. After stoppage of the supply, the reaction was carried out for 15 minutes, while adjusting the temperature in the reactor to 70 C.

(59) After completion of the polymerization, 1,3-dimethyl-2-imidazolidinone was added as a modifier in an amount equimolar to n-butyllithium used in the polymerization, and the mixture was then allowed to react for 10 minutes, while adjusting the temperature in the reactor to 70 C. The obtained modified vinyl aromatic-based copolymer was analyzed. As a result, the styrene content was 30 mass %, the polystyrene block content was 30 mass %, the vinyl bond content in the butadiene portion was 35%, the modification percentage was 75%, the weight average molecular weight was 80,000, and the molecular weight distribution was 1.03.

(60) Thereafter, the above-prepared hydrogenation catalyst was added, in an amount of 100 ppm of titanium atoms based on 100 mass parts of a non-hydrogenated vinyl aromatic-based copolymer, to the obtained modified vinyl aromatic-based copolymer. The mixture was stirred at a hydrogen pressure of 0.7 MPa for 30 minutes, while adjusting the temperature to 65 C., so that a hydrogenation reaction was carried out.

(61) After completion of the reaction, 0.25 mass parts of octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate was added as a stabilizer based on 100 mass parts of the copolymer, so as to obtain a modified vinyl aromatic-based copolymer B1. The hydrogenation percentage of the polymer B1 was 80%.

(62) <B2>

(63) 20 mass parts of styrene was added at the first step, 60 mass parts of butadiene was added at the second step, 20 mass parts of styrene was added at the third step, and n-butyllithium was added in an amount of 0.11 mass parts based on the total mass of all monomers to a reactor from the bottom thereof. Thereafter, the amount of N,N,N,N-tetramethylethylenediamine was changed so that it became 0.25 moles based on 1 mole of the n-butyllithium. Polymerization was carried out in the same manner as that of the above-described polymer B1, except for the aforementioned conditions. A modification reaction was not carried out.

(64) After completion of the polymerization, a cyclohexane solution of methanol was added to the reaction product, so that the methanol could be in an amount equimolar to 1 mole of the n-butyllithium, thereby terminating the polymerization reaction.

(65) The vinyl aromatic-based copolymer obtained as a result of the polymerization was analyzed. As a result, the styrene content was 40 mass %, the polystyrene block content was 40 mass %, the vinyl bond content in the butadiene portion was 28%, the weight average molecular weight was 75,000, and the molecular weight distribution was 1.04.

(66) Subsequently, the obtained vinyl aromatic-based copolymer was subjected to a hydrogenation reaction as in the case of the above-described polymer B1. After completion of the reaction, a stabilizer was added to the reaction product. Thus, a vinyl aromatic-based copolymer B2 having a hydrogenation percentage of 40% was obtained.

(67) <B3>

(68) 22.5 mass parts of styrene was added at the first step, 55 mass parts of butadiene was added at the second step, 22.5 mass parts of styrene was added at the third step, and n-butyllithium was added in an amount of 0.10 mass parts based on the total mass of all monomers to a reactor from the bottom thereof. Thereafter, the amount of N,N,N,N-tetramethylethylenediamine was changed so that it became 0.23 moles based on 1 mole of the n-butyllithium. Polymerization was carried out in the same manner as that of the above-described polymer B1, except for the aforementioned conditions. A modification reaction was not carried out.

(69) After completion of the polymerization, a cyclohexane solution of methanol was added to the reaction product, so that the methanol could be in an amount equimolar to 1 mole of the n-butyllithium, thereby terminating the polymerization reaction.

(70) The vinyl aromatic-based copolymer obtained as a result of the polymerization was analyzed. As a result, the styrene content was 45 mass %, the polystyrene block content was 45 mass %, the vinyl bond content in the butadiene portion was 25%, the weight average molecular weight was 70,000, and the molecular weight distribution was 1.05.

(71) Subsequently, the obtained vinyl aromatic-based copolymer was subjected to a hydrogenation reaction as in the case of the above-described polymer B1. After completion of the reaction, a stabilizer was added to the reaction product. Thus, a vinyl aromatic-based copolymer B3 having a hydrogenation percentage of 35% was obtained.

(72) <B4>

(73) From the bottom of a reactor, n-butyllithium was added to the reactor, so that the amount of the n-butyllithium became 0.07 mass parts based on the total weight of all monomers. Further, a cyclohexane solution of N,N,N,N-tetramethylethylenediamine was added to the reactor, so that the amount of the N,N,N,N-tetramethylethylenediamine became 0.3 moles based on 1 mole of the n-butyllithium. Thereafter, a cyclohexane solution containing 10 mass parts of styrene at the first step was supplied as a monomer to the reactor for approximately 5 minutes, and the temperature in the reactor was adjusted to approximately 70 C. After stoppage of the supply, the reaction was carried out for 15 minutes, while adjusting the temperature in the reactor to 70 C.

(74) Subsequently, a cyclohexane solution containing 37 mass parts of butadiene and 45 mass parts of styrene at the second step was continuously supplied at a constant rate to the reactor over 60 minutes, and during this operation, the temperature in the reactor was adjusted to a temperature from 70 to 80 C. After stoppage of the supply, the mixture was allowed to react for 10 minutes, while adjusting the temperature in the reactor to a temperature from 70 to 80 C.

(75) Finally, a cyclohexane solution containing 8 mass parts of styrene at the third step was supplied to the reactor for 5 minutes, and the temperature in the reactor was adjusted to approximately 70 C. After stoppage of the supply, the mixture was allowed to react for 15 minutes, while adjusting the temperature in the reactor to 70 C.

(76) Polymerization was carried out in the same manner as that of the polymer B1, except for the aforementioned conditions. A modification reaction was not carried out.

(77) After completion of the polymerization, a cyclohexane solution of methanol was added to the reaction product, so that the methanol could be in an amount equimolar to 1 mole of the n-butyllithium, thereby terminating the polymerization reaction.

(78) The vinyl aromatic-based copolymer obtained as a result of the polymerization was analyzed. As a result, the styrene content was 62 mass %, the polystyrene block content was 23 mass %, the vinyl bond content in the butadiene portion was 21%, the weight average molecular weight was 160,000, and the molecular weight distribution was 1.08.

(79) Subsequently, the obtained vinyl aromatic-based copolymer was subjected to a hydrogenation reaction as in the case of the above-described polymer B1. After completion of the reaction, a stabilizer was added to the reaction product. Thus, a vinyl aromatic-based copolymer B4 having a hydrogenation percentage of 35% was obtained.

(80) The composition, structure, molecular weight and measurement results of physical properties of each of the obtained vinyl aromatic-based copolymers are shown in the following Table 1.

(81) TABLE-US-00001 TABLE 1 Composition, structure and molecular weight of polymer B1 B2 B3 B4 Styrene content (mass %) in polymer 30 40 45 62 Styrene block content (mass %) in 30 40 45 23 polymer Vinyl content (%) in conjugated diene 35 28 25 21 Weight average molecular weight 8 7.5 7 16 (ten thousands) Hydrogenation percentage (%) to 80 40 35 35 double bond in conjugated diene Tan peak temperature ( C.) 55 61 66 9 Tan value at 15 C. 0.07 0.06 0.044 0.72
[(B-II) Ethylene-based Copolymer Having Unsaturated Group]
<B5>

(82) Ethylene-propylene-diene copolymer EPDM (trade name Nordel IP 4770R, manufactured by the Dow Chemical Company)

(83) ((C) Inorganic Filler)

(84) <C1>

(85) As an inorganic filler, silica Nipsil AQ (manufactured by Tosoh Silica Corporation, mean dispersed particle diameter: 0.3 m) was used.

(86) <C2>

(87) As an inorganic filler, talc JM209 (manufactured by Asada Milling Co., Ltd., mean dispersed particle diameter: 3.5 m) was used.

(88) ((D) Organic Silane Coupling Agent)

(89) <D1>

(90) As a sulfide-based organic silane coupling agent, Si69 (manufactured by Evonik Degussa Japan Co., Ltd.) was used.

(91) <D2>

(92) As a sulfide-based organic silane coupling agent, Si75 (manufactured by Evonik Degussa Japan Co., Ltd.) was used.

(93) <D3>

(94) As a vinyl-based organic silane coupling agent, GF 56 (manufactured by Wacker Asahikasei Silicone Co., Ltd.) was used.

(95) <D4>

(96) As a mercapto-based organic silane coupling agent, GF 70 (manufactured by Wacker Asahikasei Silicone Co., Ltd.) was used.

(97) ((E) Foaming Agent)

(98) As a foaming agent, Excellar AK#2 (manufactured by EIWA CHEMICAL IND. CO., LTD.) was used.

(99) ((F) Crosslinking Agent)

(100) As an organic oxide, PERCUMYL D (NOF Corporation) was used.

Example 1

(101) First, using an extruder as a melt-kneader, 20 mass parts of the (A1) ethylene-1-butene copolymer, 10 mass parts of the (B1) vinyl aromatic-based copolymer, 5 mass parts of the (C1) inorganic filler, silica Nipsil AQ, and 0.4 mass parts of the (D2) organic silane coupling agent Si75, which were the blending components in the first step shown in Table 2 below, were kneaded at a kneading temperature of 200 C. to obtain a master pellet.

(102) Subsequently, using a pressure kneader as a melt-kneader, the master pellet that was the kneaded product obtained in the first step, and 70 mass parts of the (A1) ethylene-1-butene copolymer and other additives, which were the blending components in the second step shown in Table 2 below, were kneaded at a kneading temperature of approximately 130 C. for a kneading time of 10 minutes.

(103) Thereafter, using a two-roll open mill as a melt-kneader, the kneaded product obtained in the second step, and 9 mass parts of the (E) foaming agent, Excellar AK#2 and 0.7 mass parts of the (F) organic oxide, PERCUMYL D, which were the blending components in the third step shown in Table 2 below, were kneaded at a kneading temperature of 100 C. for a kneading time of 5 minutes to obtain a foamable composition.

(104) Thereafter, using a compression molding machine, the obtained foamable composition was compression-molded at a temperature of 160 C. under a pressure of 150 kgf/cm.sup.2 for 20 minutes.

(105) After that, the pressure was released to obtain a primary crosslinked foam.

(106) This primary crosslinked foam was compression-molded at a compression ratio of 1455%, thereby producing a second-order crosslinked foam.

(107) The physical properties of the second-order crosslinked foam were subsequently measured according to the methods described above.

Example 2

(108) The (B2) vinyl aromatic-based copolymer was used, instead of the (B1) vinyl aromatic-based copolymer in the first step shown in Table 2 below. Except for this condition, a second-order crosslinked foam was prepared as in Example 1. The physical properties thereof were measured according to the methods described above.

Example 3

(109) The (B3) vinyl aromatic-based copolymer was used, instead of the (B1) vinyl aromatic-based copolymer in the first step shown in Table 2 below. Except for this condition, a second-order crosslinked foam was prepared as in Example 1. The physical properties thereof were measured according to the methods described above.

Example 4

(110) The (C2) inorganic filler, talc JM209 was used, instead of the (C1) inorganic filler, silica Nipsil AQ in the first step shown in Table 2 below. Except for this condition, a second-order crosslinked foam was prepared as in Example 3. The physical properties thereof were measured according to the methods described above.

Example 5

(111) The (D3) organic silane coupling agent was used, instead of the (D2) organic silane coupling agent in the first step shown in Table 2 below. Except for this condition, a second-order crosslinked foam was prepared as in Example 3. The physical properties thereof were measured according to the methods described above.

Example 6

(112) The (D4) organic silane coupling agent was used, instead of the (D2) organic silane coupling agent in the first step shown in Table 2 below. Except for this condition, a second-order crosslinked foam was prepared as in Example 3. The physical properties thereof were measured according to the methods described above.

Example 7

(113) The (B5) ethylene-based copolymer containing an unsaturated group was used, instead of the (B1) vinyl aromatic-based copolymer in the first step shown in Table 2 below. Except for this condition, a second-order crosslinked foam was prepared as in Example 1. The physical properties thereof were measured according to the methods described above.

Example 8

(114) 20 mass parts of the (A1) ethylene-1-butene copolymer, 20 mass parts of the (A2) ethylene-1-butene copolymer, 5 mass parts of the (C1) inorganic filler, silica Nipsil AQ, and 0.4 mass parts of the (D3) organic silane coupling agent GF 56 were used as blending components of the materials in the first step shown in Table 2 below. Moreover, 60 mass parts of the (A1) ethylene-1-butene copolymer was used as a blending component of the materials in the second step. Except for these conditions, a second-order crosslinked foam was prepared as in Example 1. The physical properties thereof were measured according to the methods described above.

Example 9

(115) 0.5 mass parts of the (D1) organic silane coupling agent was used, instead of the (D2) organic silane coupling agent, as a blending component of the materials in the first step shown in Table 2 below. 50 mass parts of the (A3) ethylene-vinyl acetate copolymer and 20 mass parts of the (A1) ethylene-1-butene copolymer were used in the second step. 7 mass parts of the (E) foaming agent, Excellar AK#2 was used as a blending component in the third step. Except for these conditions, a second-order crosslinked foam was prepared as in Example 3. The physical properties thereof were measured according to the methods described above.

Example 10

(116) 20 mass parts of the (A1) ethylene-1-butene copolymer, 20 mass parts of the (A2) ethylene-1-butene copolymer, 5 mass parts of the (C1) inorganic filler, silica Nipsil AQ, and 0.4 mass parts of the (D1) organic silane coupling agent Si69 were used as blending components in the first step shown in Table 2 below. 60 mass parts of the (A1) ethylene-1-butene copolymer was used as a blending component in the second step. 7 mass parts of the (E) foaming agent, Excellar AK#2 and 0.7 mass parts of the (F) organic oxide, PERCUMYL D were used as blending components in the third step. Except for these conditions, a second-order crosslinked foam was prepared as in Example 1. The physical properties thereof were measured according to the methods described above.

Comparative Example 1

(117) The (C1) inorganic filler and the (D2) organic silane coupling agent, which were the additives in the first step shown in Table 3 below, were not blended. Except for this condition, a second-order crosslinked foam was prepared as in Example 3. The physical properties thereof were measured according to the methods described above.

Comparative Example 2

(118) The (D2) organic silane coupling agent, which was the additive in the first step shown in Table 3 below, was not blended. Except for this condition, a second-order crosslinked foam was prepared as in Example 3. The physical properties thereof were measured according to the methods described above.

Comparative Example 3

(119) The (C1) inorganic filler, which was the additive in the first step shown in Table 3 below, was not blended. Except for this condition, a second-order crosslinked foam was prepared as in Example 3. The physical properties thereof were measured according to the methods described above.

Comparative Example 4

(120) The (D2) organic silane coupling agent, which was the additive in the first step shown in Table 3 below, was not blended. Except for this condition, a second-order crosslinked foam was prepared as in Example 4. The physical properties thereof were measured according to the methods described above.

Comparative Example 5

(121) The (C1) inorganic filler and the (D2) organic silane coupling agent, which were the additives in the first step shown in Table 3 below, were not blended. Except for this condition, a second-order crosslinked foam was prepared as in Example 5. The physical properties thereof were measured according to the methods described above.

Comparative Example 6

(122) The (A1) ethylene-based copolymer in the first step shown in Table 3 below, was not blended, and the amount of the (E) foaming agent, Excellar AK#2 was changed from 9 mass parts to 7 mass parts. Except for these conditions, a second-order crosslinked foam was prepared as in Example 3. The physical properties thereof were measured according to the methods described above.

Example 11

(123) First, using an extruder as a melt-kneader, 20 mass parts of the (A2) ethylene-1-butene copolymer, 60 mass parts of the (B4) vinyl aromatic-based copolymer, 10 mass parts of the (C1) inorganic filler, silica Nipsil AQ, and 0.8 mass parts of the (D2) organic silane coupling agent Si75, which were the blending components in the first step shown in Table 4 below, were kneaded at a kneading temperature of 200 C. to obtain a master pellet.

(124) Subsequently, using a pressure kneader as a melt-kneader, the master pellet that was the kneaded product obtained in the first step, and 20 mass parts of the (A2) ethylene-1-butene copolymer and other additives, which were the blending components in the second step shown in Table 4 below, were kneaded at a kneading temperature of 130 C. for a kneading time of 10 minutes.

(125) Thereafter, using a two-roll open mill as a melt-kneader, the kneaded product obtained in the second step, and 2 mass parts of the (E) foaming agent, Excellar AK#2 and 0.35 mass parts of the (F) organic oxide, PERCUMYL D, which were the blending components in the third step shown in Table 4 below, were kneaded at a kneading temperature of 100 C. for a kneading time of 5 minutes to obtain a foamable composition.

(126) Thereafter, using a compression molding machine, the obtained foamable composition was compression-molded at a temperature of 160 C. under a pressure of 150 kgf/cm.sup.2 for 20 minutes.

(127) After that, the pressure was released to obtain a primary crosslinked foam. This primary crosslinked foam was compression-molded at a compression percentage of 1455% to obtain a second-order crosslinked foam.

(128) Subsequently, the physical properties of the second-order crosslinked foam were measured according to the methods described above.

Example 12

(129) In the first step shown in Table 4 below, the amount of the (B4) vinyl aromatic-based copolymer was changed from 60 mass parts to 70 mass parts; in the second step, the amount of the (A2) ethylene-1-butene copolymer was changed from 20 mass parts to 10 mass parts; and further, in the third step, the amount of the (E) foaming agent, Excellar AK#2 was changed from 2 mass parts to 2.5 mass parts, and the amount of the (F) organic oxide, PERCUMYL D was changed from 0.35 mass parts to 0.44 mass parts. Except for this condition, a second-order crosslinked foam was prepared as in Example 1. The physical properties thereof were measured according to the methods described above.

Comparative Example 7

(130) The (C1) inorganic filler and the (D2) organic silane coupling agent, which were the additives in the first step shown in Table 4 below, were not blended. Except for this condition, a second-order crosslinked foam was prepared as in Example 11. The physical properties thereof were measured according to the methods described above.

(131) Table 2 below shows the results obtained in Examples 1 to 10; Table 3 below shows the results obtained in Comparative Examples 1 to 6; and Table 4 below shows the results obtained in Examples 11 and 12 and Comparative Example 7, respectively.

(132) TABLE-US-00002 TABLE 2 Example Blending component 1 2 3 4 5 First step Ethylene-1-butene copolymer (A1) 20 20 20 20 20 Extruder 200 C. Ethylene-1-butene copolymer (A2) Vinyl aromatic-based copolymer (B1) 10 Vinyl aromatic-based copolymer (B2) 10 Vinyl aromatic-based copolymer (B3) 10 10 10 Ethylene-based copolymer containing unsaturated group (B5) Additive Inorganic filler (C1) 5 5 5 5 Inorganic filler (C2) 5 Organic silane coupling agent (D1) Organic silane coupling agent (D2) 0.4 0.4 0.4 0.4 Organic silane coupling agent (D3) 0.4 Organic silane coupling agent (D4) Second step Ethylene-1-butene copolymer (A1) 70 70 70 70 70 Kneader 130 C. Ethylene-vinyl acetate copolymer (A3) Additive Zinc oxide 1.2 1.2 1.2 1.2 1.2 Stearic acid 0.4 0.4 0.4 0.4 0.4 Titanium oxide 2.0 2.0 2.0 2.0 2.0 Zinc stearate 0.8 0.8 0.8 0.8 0.8 Third step Additive Foaming agent (E) 9.0 9.0 9.0 9.0 9.0 Roll 100 C. Crosslinking agent (F) 0.7 0.7 0.7 0.7 0.7 Specific gravity Primary crosslinked foam (g/cc) 0.075 0.079 0.082 0.077 0.080 Specific gravity Second-order crosslinked foam (g/cc) 0.109 0.112 0.113 0.097 0.111 Hardness Momentary value (Shore C) 50 54 57 51 55 Tensile strength (kgf/cm.sup.2) 42 46 50 45 51 Elongation (%) 240 230 210 230 220 Tear strength (kgf/cm) 10 12 11 10 11 Peel strength (kgf/cm) 2.5 2.4 2.7 2 2.3 Permanent compression set (%) 14 15 16 23 19 Impact resilience (%) 50 48 46 48 46 Adhesive strength 30 minutes (kgf/cm) 2.9 2.8 2.7 2.5 2.8 Peel/Specific gravity (kgf .Math. cc/g .Math. cm) 22.9 21.4 23.9 20.6 20.7 Example Blending component 6 7 8 9 10 First step Ethylene-1-butene copolymer (A1) 20 20 20 20 20 Extruder 200 C. Ethylene-1-butene copolymer (A2) 20 20 Vinyl aromatic-based copolymer (B1) Vinyl aromatic-based copolymer (B2) Vinyl aromatic-based copolymer (B3) 10 10 Ethylene-based copolymer containing 10 unsaturated group (B5) Additive Inorganic filler (C1) 5 5 5 5 5 Inorganic filler (C2) Organic silane coupling agent (D1) 0.5 0.5 Organic silane coupling agent (D2) 0.4 Organic silane coupling agent (D3) 0.4 Organic silane coupling agent (D4) 0.4 Second step Ethylene-1-butene copolymer (A1) 70 70 60 20 60 Kneader 130 C. Ethylene-vinyl acetate copolymer (A3) 50 Additive Zinc oxide 1.2 1.2 1.2 1.2 1.2 Stearic acid 0.4 0.4 0.4 0.4 0.4 Titanium oxide 2.0 2.0 2.0 2.0 2.0 Zinc stearate 0.8 0.8 0.8 0.8 0.8 Third step Additive Foaming agent (E) 9.0 9.0 9.0 7.0 7.0 Roll 100 C. Crosslinking agent (F) 0.7 0.7 0.7 0.7 0.7 Specific gravity Primary crosslinked foam (g/cc) 0.075 0.073 0.074 0.110 0.101 Specific gravity Second-order crosslinked foam (g/cc) 0.102 0.096 0.103 0.149 0.142 Hardness Momentary value (Shore C) 52 50 51 55 53 Tensile strength (kgf/cm.sup.2) 47 41 43 59 55 Elongation (%) 240 250 200 230 220 Tear strength (kgf/cm) 10 9 9 13 11 Peel strength (kgf/cm) 2.1 2 2.1 3.2 3 Permanent compression set (%) 24 18 25 13 24 Impact resilience (%) 47 43 42 44 43 Adhesive strength 30 minutes (kgf/cm) 2.7 2.6 2.8 3.2 2.9 Peel/Specific gravity (kgf .Math. cc/g .Math. cm) 20.6 20.8 20.4 21.5 21.1

(133) TABLE-US-00003 TABLE 3 Comparative Example Blending component 1 2 3 4 5 6 First step Ethylene-1-butene copolymer (A1) 20 20 20 20 20 Extruder 200 C. Ethylene-1-butene copolymer (A2) 20 Vinyl aromatic-based copolymer (B1) Vinyl aromatic-based copolymer (B2) 100 Vinyl aromatic-based copolymer (B3) 10 10 10 10 Ethylene-based copolymer containing unsaturated group (B5) Additive Inorganic filler (C1) 5 5 5 Inorganic filler (C2) Organic silane coupling agent (D1) Organic silane coupling agent (D2) 0.4 0.4 Organic silane coupling agent (D3) Organic silane coupling agent (D4) Second step Ethylene-1-butene copolymer (A1) 70 70 70 20 60 Kneader 130 C. Ethylene-vinyl acetate copolymer (A3) 50 Additive Zinc oxide 1.2 1.2 1.2 1.2 1.2 1.2 Stearic acid 0.4 0.4 0.4 0.4 0.4 0.4 Titanium oxide 2.0 2.0 2.0 2.0 2.0 2.0 Zinc stearate 0.8 0.8 0.8 0.8 0.8 0.8 Third step Additive Foaming agent (E) 9.0 9.0 9.0 7.0 7.0 7.0 Roll 100 C. Crosslinking agent (F) 0.7 0.7 0.7 0.7 0.7 0.7 Specific gravity Primary crosslinked foam (g/cc) 0.073 0.077 0.074 0.105 0.090 Poorly molded Specific gravity Second-order crosslinked foam (g/cc) 0.106 0.112 0.108 0.14 0.129 unmeasurable Hardness Momentary value (Shore C) 40 51 47 52 40 Tensile strength (kgf/cm.sup.2) 36 45 45 49 47 Elongation (%) 240 160 200 160 230 Tear strength (kgf/cm) 8 6 7 9 9 Peel strength (kgf/cm) 1.7 1.6 1.9 2.5 2.1 Permanent compression (%) 36 37 30 27 32 set Impact resilience (%) 46 45 46 46 42 Adhesive strength (kgf/cm) 1.6 1.8 2 2.1 1.9 30 minutes later Peel/Specific gravity (kgf .Math. cc/g .Math. cm) 16.0 14.3 17.6 17.9 16.3

(134) TABLE-US-00004 TABLE 4 Example Comparative Blending component 11 12 Example 7 First step Ethylene-1-butene copolymer (A2) 20 20 20 Extruder 200 C. Vinyl aromatic-based copolymer (B4) 60 70 60 Additive Inorganic filler (C1) 10 10 Organic silane coupling agent (D2) 0.8 0.8 Second step Ethylene-1-butene copolymer (A1) 10 Kneader 130 C. Ethylene-1-butene copolymer (A2) 20 20 Additive Zinc oxide 1.12 1.12 1.12 Stearic acid 0.32 0.32 0.32 Titanium oxide 2.00 2.00 2.00 Zinc stearate 0.64 0.64 0.64 Third step Additive Foaming agent (E) 2.00 2.50 2.00 Roll 100 C. Crosslinking agent (F) 0.35 0.44 0.35 Specific gravity Primary crosslinked foam (g/cc) 0.30 0.22 0.27 Specific gravity Second-order crosslinked foam (g/cc) 0.43 0.32 0.41 Hardness Momentary value 54 52 47 Peel strength (kgf/cm) 3.9 3.3 2.2 Permanent compression set (%) 13 15 31 Impact resilience (%) 13 11 13 Adhesive strength 30 minutes later (kgf/cm) 3.3 3 1.5

(135) The specific gravities of the second-order crosslinked foams of Examples 1 to 8 and Comparative Examples 1 to 3 were substantially equal to one another.

(136) The second-order crosslinked foam of Examples 1 to 8 had a hardness of 50 to 57, a permanent compression set of 14 to 25%, a peel strength of 2.0 to 2.7 kgf/cm, and an adhesive strength of 2.5 to 2.9 kgf/cm.

(137) On the other hand, all of the second-order crosslinked foams of Comparative Examples 1 to 3 had a hardness of 40 to 51, a permanent compression set of 30 to 37%, a peel strength of 1.6 to 1.9 kgf/cm, and an adhesive strength of 1.6 to 2.0 kgf/cm, and thus, the results of Comparative Examples 1 to 3 were poorer than those of the Example.

(138) The specific gravities of the second-order crosslinked foams of Example 9 and Comparative Example 4 were substantially equal to one another.

(139) The second-order crosslinked foam of Example 9 had a hardness of 55, a permanent compression set of 13%, a peel strength of 3.2 kgf/cm, and an adhesive strength of 3.2 kgf/cm.

(140) On the other hand, the second-order crosslinked foam of Comparative Example 4 had a hardness of 52, a permanent compression set of 27%, a peel strength of 2.5 kgf/cm, and an adhesive strength of 2.1 kgf/cm, and thus, the results of Comparative Example 4 were poorer than those of the Example.

(141) The specific gravities of the second-order crosslinked foams of Example 10 and Comparative Example 5 were substantially equal to one another.

(142) The second-order crosslinked foam of Example 10 had a hardness of 53, a permanent compression set of 24%, a peel strength of 3.0 kgf/cm, and an adhesive strength of 2.9 kgf/cm.

(143) On the other hand, the second-order crosslinked foam of Comparative Example 5 had a hardness of 40, a permanent compression set of 32%, a peel strength of 2.5 kgf/cm, and an adhesive strength of 1.9 kgf/cm, and thus, the results of Comparative Example 5 were poorer than those of the Example.

(144) In addition, a foam whose physical properties were measurable could not be obtained in Comparative Example 6.

(145) The specific gravities of the second-order crosslinked foams of Examples 11 and 12 and Comparative Example 7 were substantially equal to one another.

(146) The second-order crosslinked foams of Examples 11 and 12 had a hardness of 52 to 54, a permanent compression set of 13 to 15%, a peel strength of 3.3 to 3.9 kgf/cm, and an adhesive strength of 3.0 to 3.3 kgf/cm.

(147) On the other hand, the second-order crosslinked foam of Comparative Example 7 had a hardness of 47, a permanent compression set of 31%, a peel strength of 2.2 kgf/cm, and an adhesive strength of 1.5 kgf/cm, and thus, the results of Comparative Example 7 were poorer than those of the Examples.

(148) The Examples revealed that the foamable composition of the present embodiment is lightweight and has also excellent permanent compression set, peel strength, and adhesive strength.

INDUSTRIAL APPLICABILITY

(149) The foams of the present invention have industrial applicability as various molded articles such as automobile member, civil engineering and construction applications, household appliance parts, sporting goods, sundries, and stationery.