JP2006008777A - Foamed body and its application - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crosslinked foamed body having a low specific gravity, an Asker C hardness of ≥45 and a small compression set (CS), and excellent in tensile strength characteristics and tearing strength characteristics, and to provide a laminate using the foamed body. <P>SOLUTION: The crosslinked foamed body consists of a resin composition containing 100 pts.wt. of an ethylene-α-olefin copolymer (A) and 0-50 pts.wt. of an ethylene-polar monomer copolymer (B) and is characterized by having an Asker C hardness of ≥45, a specific gravity (skin-on) of ≤0.13 and a tensile strength characteristic (JIS K 6301-2) of ≥2.5 MPa. The ethylene-α-olefin copolymer (A) is one consisting of ethylene and a 3-20C α-olefin, its density being in the range of 900-910 kg/m<SP>3</SP>, its melt flow rate (MFR2) at 190°C under 2.16 kg load being in the range of 0.1-10 g/10 minutes, and its Mw/Mn being in the range of 1.5-3.0. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a foam. More specifically, the foam has a low specific gravity, an Asker C hardness of 45 or more, a small permanent compression strain (CS), and excellent tensile strength characteristics and tear strength characteristics (non-crosslinked and crosslinked foam). Body).

  In order to obtain a low specific gravity, that is, lightweight, flexible, and high mechanical strength resin, the technology using cross-linked foam is widely applied to interior / exterior materials, interior parts, automotive parts such as door glass runs, packaging materials, daily necessities, etc. It is used. This is because if the resin is only foamed for weight reduction, the mechanical strength is reduced, so the molecular chain is bonded by the resin crosslinking reaction to reduce the mechanical strength while reducing the weight. It is possible to achieve this.

  In addition, cross-linked foam of resin is also used for footwear or footwear parts such as sports shoes (mainly midsole), but this is lightweight and suppresses deformation due to long-term use, This is because there is a demand for a material having mechanical strength and rebound resilience that can withstand severe use conditions.

  Conventionally, a cross-linked foam of ethylene / vinyl acetate copolymer has been used and widely known for shoe soles, but a cross-linked foam molded using this ethylene / vinyl acetate copolymer composition is Since the specific gravity is high and the compression set is large, for example, when used for a shoe sole, there is a problem that the shoe sole is compressed by long-term use and mechanical strength such as rebound resilience is lost. .

  JP-A-9-501447 and JP-A-11-206406 disclose a crosslinked foam using an ethylene / α-olefin copolymer, an ethylene / vinyl acetate copolymer and an ethylene / α-olefin copolymer. The invention relating to the cross-linked foam using the mixture with each other has been described, but in these inventions, although low specific gravity and compression set are improved, sufficient performance has not been obtained (Patent Documents) 1, 2).

  Japanese Patent Laid-Open No. 2000-344924 relating to the present inventor discloses that the Asker C hardness is in the range of 20 to 80, the specific gravity is low, the permanent compression strain (CS) is small, and the tensile strength characteristics and tear strength characteristics In addition, an invention relating to a foam (non-crosslinked and crosslinked foam) excellent in rebound resilience is described. However, when the specific gravity is further reduced, there is a problem that the Asker C hardness and the tensile strength characteristics are lowered (Patent Document 3).

The present inventors have intensively studied to suppress the above-described decrease in hardness at high temperatures, and a resin composition containing an ethylene / α-olefin copolymer (A), and further an ethylene / α-olefin copolymer (A). And a resin composition containing ethylene / polar monomer copolymer (B), a foam having a high hardness and excellent tensile strength characteristics despite a low specific gravity can be obtained. It came to complete.
JP-T 9-501447, JP-A-11-206406 JP 2000-344924 A

  An object of the present invention is to provide a crosslinked foam having a low specific gravity, an Asker C hardness of 45 or more, a small permanent compression strain (CS), and excellent tensile strength characteristics and tear strength characteristics, and a laminate using the foam. It is intended to provide.

The foam resin composition according to the present invention is (1) a resin comprising 0 to 50 parts by weight of an ethylene / polar monomer copolymer (B) with respect to an ethylene / α-olefin copolymer (A) having the following properties: It is a crosslinked foamed product having an Asker C hardness of 45 or more, a specific gravity (skin-on) of 0.13 or less, and a tensile strength characteristic (JIS K6301-2) of 2.5 MPa or more. It is characterized by.

  An ethylene / α-olefin copolymer comprising ethylene and an α-olefin having 3 to 20 carbon atoms, having a density (ASTM D1505, 23 ° C.) in the range of 900 to 910 kg / m 3, 190 ° C. and 2.16 kg. The melt flow rate (MFR2) under load (ASTM D1238, load 2.16 kg, 190 ° C.) is in the range of 0.1 to 10 g / 10 min, and the molecular weight distribution index evaluated by the GPC method: Mw / Mn is 1. It is in the range of 5-3.0.

Or
(2) The ethylene / α-olefin copolymer (A) is a crosslinked foam having the following properties.
(i) Ratio of melt flow rate (MFR10) at 190 ° C. and 10 kg load to melt flow rate (MFR2) at 190 ° C. and 2.16 kg load:
MFR10 / MFR2 satisfies the following equation:
Mw / Mn + 5.0 ≦ MFR10 / MFR2
In addition
(ii) The intensity ratio of Tαβ to Tαα (Tαβ / Tαα) in the 13C-NMR spectrum is 0.5 or less,
(iii) B value calculated | required from a 13C-NMR spectrum and following General formula (1) is 0.9-1.5.
B value = [POE] / (2 · [PE] [PO]) (1)
(Wherein [PE] is the mole fraction of structural units derived from ethylene in the copolymer, and [PO] is the mole fraction of structural units derived from α-olefin in the copolymer. And [POE] is the ratio of the number of ethylene / α-olefin chains to the total dyad chains in the copolymer.)
Or
(3) The ethylene / α-olefin copolymer (A) is a cross-linked foam which is an ethylene / 1-butene copolymer. Or
(4) A cross-linked foam containing a cross-linking aid (E) with respect to the ethylene / α-olefin copolymer (A). Or
(5) A cross-linked foam obtained by secondary compression of the foam according to any one of (1) to (4) above. Or
(6) a layer made of the foam according to any one of (1) to (5) above,
It is a laminate having a layer made of at least one material selected from the group consisting of polyolefin, polyurethane, rubber, leather and artificial leather. Or
(7) A footwear comprising the foam according to any one of (1) to (5) or the laminate according to (6). Or
(8) A footwear component comprising the foam according to any one of (1) to (5) or the laminate according to (6). Or
(9) The footwear component is the footwear component according to (8), wherein the footwear component is a midsole, an inner sole, or a sole.

  The cross-linked foam according to the present invention has characteristics such as low compression set, high tear strength, and high rebound resilience. Furthermore, the cross-linked foam according to the present invention has high hardness and excellent tensile strength characteristics despite its low specific gravity.

Hereinafter, the foam according to the present invention will be described in detail.
The resin composition for foams according to the present invention, preferably the resin composition for crosslinked foams, contains a specific ethylene / α-olefin copolymer (A), preferably a specific ethylene / α-olefin copolymer. It contains a coalescence (A) and an ethylene / polar monomer copolymer (B), and further contains a foaming agent (C), an organic peroxide (D), and a crosslinking aid (E) as necessary. . In particular, it is generally preferred that the specific ethylene / α-olefin copolymer (A), the ethylene / polar monomer copolymer (B) and the foaming agent (C) are essential.

    The foam according to the present invention is obtained by foaming or cross-linking foaming the composition, but the cross-linked foam is preferably used. Examples of the crosslinking method include thermal crosslinking and ionizing radiation crosslinking. In the case of thermal crosslinking, it is necessary to mix an organic peroxide (D) and a crosslinking aid (E) in this composition. In the case of ionizing radiation crosslinking, a crosslinking aid may be blended.

Ethylene / α-olefin copolymer (A)
The ethylene / α-olefin copolymer (A) used in the present invention is a low crystalline random or block copolymer comprising ethylene and an α-olefin having 3 to 20 carbon atoms, and has a density (ASTM D 1505) is 900 to 910 kg / m 3, and melt flow rate (MFR; ASTM D 1238, 190 ° C., load 2.16 kg) is 0.1 to 10 g / 10 min, preferably 0.5 to 5 g / 10 min. It is desirable. The ethylene / α-olefin copolymer (A) used in the present invention may be a blend of two or more ethylene / α-olefin copolymers.

    The α-olefin copolymerized with ethylene is an α-olefin having 3 to 20 carbon atoms, specifically, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, Examples include 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-hexadecene, 1-octadecene, 1-nonadecene, 1-eicocene, 4-methyl-1-pentene, and the like. Of these, α-olefins having 3 to 10 carbon atoms are preferable, and propylene, 1-butene, 1-hexene and 1-octene are particularly preferable. These α-olefins may be used alone or in combination of two or more.

    The ethylene / α-olefin copolymer (A) is composed of 92 to 97 mol% of units derived from ethylene and 3 to 8 mol% of units derived from α-olefin having 3 to 20 carbon atoms. It is desirable to contain in the quantity. Here, the total amount of ethylene and α-olefin is 100 mol%.

    In addition to these units, the ethylene / α-olefin copolymer (A) may contain units derived from other polymerizable monomers as long as the object of the present invention is not impaired.

    Specific examples of the ethylene / α-olefin copolymer (A) include an ethylene / propylene copolymer, an ethylene / 1-butene copolymer, an ethylene / propylene / 1-butene copolymer, and an ethylene / propylene copolymer. Examples thereof include an ethylidene norbornene copolymer, an ethylene / 1-hexene copolymer, and an ethylene / 1-octene copolymer. Of these, ethylene / propylene copolymers, ethylene / 1-butene copolymers, ethylene / 1-hexene copolymers, ethylene / 1-octene copolymers, and the like are preferably used. A copolymer is preferably used. These copolymers are random or block copolymers, but are preferably random copolymers.

    The ethylene / α-olefin copolymer (A) has a crystallinity measured by X-ray diffraction method of usually 40% or less, preferably 10 to 35% or less.

    The ethylene / α-olefin copolymer (A) has a molecular weight distribution (Mw / Mn) determined by gel permeation chromatography (GPC) of 1.5 to 3.0, preferably 1.7 to. It is preferable to be within the range of 2.5. When an ethylene / α-olefin copolymer (A) having a molecular weight distribution (Mw / Mn) within the above range is used, a composition capable of preparing a foam excellent in compression set and formability is obtained. It is done. The ethylene / α-olefin copolymer (A) as described above usually exhibits properties as an elastomer.

The ethylene / α-olefin copolymer (A) was measured in accordance with ASTM D 1238 at 190 ° C. under a load of 10 kg and a melt flow rate (MFR10) measured under a load of 2.16 kg ( The ratio (MFR10 / MFR2) to MFR2) is the molecular weight distribution (Mw / Mn) and the following formula: Mw / Mn + 5.0 ≦ MFR10 / MFR2
If the above relationship is satisfied, a composition (non-crosslinked foam, cross-linked foam) having a high expansion ratio, that is, a low specific gravity, high elasticity, excellent compression set and shapeability can be prepared. Things are obtained.

    The ethylene / α-olefin copolymer (A) of the present invention additionally has a Tαβ to Tαα intensity ratio (Tαβ / Tαα) in the 13C-NMR spectrum of 0.5 or less, preferably 0.4 or less. preferable.

    Here, Tαα and Tαβ in the 13C-NMR spectrum are peak intensities of CH2 in the structural unit derived from an α-olefin having 3 or more carbon atoms, and two types having different positions with respect to the tertiary carbon as shown below. Means CH2.

    Such a Tαβ / Tαα intensity ratio can be obtained as follows. The 13 C-NMR spectrum of the ethylene / α-olefin copolymer [B] is measured using, for example, a JEOL-GX270 NMR measuring apparatus manufactured by JEOL Ltd. The measurement is based on 67.8 MHz, 25 ° C., d6-benzene (128 ppm) using a mixed solution of hexachlorobutadiene / d6-benzene = 2/1 (volume ratio) adjusted to a sample concentration of 5% by weight. To do. The measured 13 C-NMR spectrum is analyzed according to the proposal of Lindeman Adams (Analysis Chemistry 43, p1245 (1971)) and J.C. Randall (Review Macromolecular Chemistry Physics, C29, 201 (1989)) to obtain the Tαβ / Tαα intensity ratio.

    Further, the ethylene / α-olefin copolymer (A) of the present invention additionally has a B value of 0.9 to 1.5, preferably 0.95, as determined from the 13C-NMR spectrum and the following general formula (1). It is preferable that it is -1.2.

B value = [POE] / (2 · [PE] [PO]) (1)
(Wherein [PE] is the mole fraction of structural units derived from ethylene in the copolymer, and [PO] is the mole fraction of structural units derived from α-olefin in the copolymer. [POE] is the ratio of the number of ethylene / α-olefin chains to the total dyad chain in the copolymer.) This B value is the same as the ethylene and ethylene / α-olefin copolymer in the copolymer. It is an index that represents the distribution state of α-olefins with 3 to 20 carbon atoms, based on reports from JCRandall (Macromolecules, 15, 353 (1982)), J.Ray (Macromolecules, 10, 773 (1977)), etc. Can be sought.

  The B value of the ethylene / α-olefin copolymer (A) is usually 13 C-NMR of a sample in which about 200 mg of ethylene / α-olefin copolymer is uniformly dissolved in 1 ml of hexachlorobutadiene in a 10 mmφ sample tube. The spectrum is determined by measuring under the conditions of a measurement temperature of 120 ° C., a measurement frequency of 25.05 MHz, a spectrum width of 1500 Hz, a pulse repetition time of 4.2 sec., And a pulse width of 6 μsec.

    The larger the B value, the shorter the block chain of the ethylene or α-olefin copolymer, the more uniform the distribution of ethylene and α-olefin, and the narrower the composition distribution of the copolymer rubber. In addition, as the B value becomes smaller than 1.0, the composition distribution of the ethylene / α-olefin copolymer becomes wider and the handling property is worse.

  The ethylene / α-olefin copolymer (A) as described above can be produced by a conventionally known method using a vanadium catalyst, a titanium catalyst or a metallocene catalyst. In particular, the solution polymerization method described in JP-A-62-1121709 is preferable.

Ethylene / polar monomer copolymer (B)
Examples of the polar monomer of the ethylene / polar monomer copolymer (B) used in the present invention include unsaturated carboxylic acids, salts thereof, esters thereof, amides, vinyl esters, and carbon monoxide. More specifically, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, itaconic anhydride, lithium of these unsaturated carboxylic acids, sodium, Monovalent metal salts such as potassium, polyvalent metal salts such as magnesium, calcium and zinc, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, nbutyl acrylate, isooctyl acrylate, methyl methacrylate Illustrative examples of unsaturated carboxylic acid esters such as ethyl methacrylate, isobutyl methacrylate and dimethyl maleate, vinyl esters such as vinyl acetate and vinyl propionate, carbon monoxide and sulfur dioxide. Can do.

  More specifically, the ethylene / polar monomer copolymer (B) includes an ethylene / acrylic acid copolymer, an ethylene / unsaturated carboxylic acid copolymer such as an ethylene / methacrylic acid copolymer, and the ethylene / unsaturated copolymer. An ionomer in which part or all of the carboxyl groups of the carboxylic acid copolymer are neutralized with the above metal, ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / methyl methacrylate copolymer, Ethylene / isobutyl acrylate copolymer, ethylene / unsaturated carboxylic acid ester copolymer such as ethylene / n-butyl acrylate copolymer, ethylene / isobutyl acrylate / methacrylic acid copolymer, ethylene / n-butyl acrylate・ Ethylene such as methacrylic acid copolymer ・ Unsaturated carboxylic acid ester ・ Unsaturated carboxylic acid Some or all of the copolymer and its carboxyl group may be exemplified an ionomer neutralized with the metal, an ethylene-vinyl ester copolymers such as ethylene-vinyl acetate copolymer, etc. as a representative example.

  Among these, a copolymer of ethylene and a polar monomer selected from an unsaturated carboxylic acid, a salt thereof, an ester thereof, and vinyl acetate is preferable, and an ethylene / (meth) acrylic acid copolymer or an ionomer thereof is particularly preferable. An ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer, or an ionomer thereof, or an ethylene / vinyl acetate copolymer is preferable, and an ethylene / vinyl acetate copolymer is most preferable.

  The ethylene / polar monomer copolymer (B) varies depending on the kind of the polar monomer, but the polar monomer content is preferably 1 to 50% by weight, particularly preferably 5 to 45% by weight. Such an ethylene / polar monomer copolymer also has a melt flow rate of 0.05 to 500 g / 10 min at 190 ° C. and a load of 2160 g in consideration of molding processability and mechanical strength. It is preferable to use the one of 100 g / 10 min. A copolymer of ethylene and unsaturated carboxylic acid, unsaturated carboxylic acid ester, vinyl ester or the like can be obtained by radical copolymerization at high temperature and high pressure. A copolymer (ionomer) of a metal salt of ethylene and an unsaturated carboxylic acid can be obtained by reacting an ethylene / unsaturated carboxylic acid copolymer with a corresponding metal compound.

  When the ethylene / polar monomer copolymer (B) used in the present invention is an ethylene / vinyl acetate copolymer, the vinyl acetate content in the ethylene / vinyl acetate copolymer is 10 to 30% by weight, preferably 15%. -30% by weight, more preferably 10-25% by weight.

    The ethylene / vinyl acetate copolymer has a melt flow rate (MFR; ASTM D 1238, 190 ° C., load 2.16 kg) of 0.1 to 50 g / 10 min, preferably 0.5 to 20 g / 10 min. More preferably, it is 0.5-5 g / 10min.

  The ethylene / polar monomer copolymer (B) is 0 to 50 parts by weight, preferably 5 to 30 parts by weight, more preferably 5 to 10 parts per 100 parts by weight of the ethylene / α-olefin copolymer (A). Used in parts by weight. When ethylene / polar monomer copolymer (B) is a copolymer of ethylene and unsaturated carboxylic acid, when used in the above proportion, it adheres to tear strength characteristics and other layers made of polyurethane, rubber, leather, etc. An elastomer composition that can provide a crosslinked foam having excellent properties can be obtained. When the ethylene / polar monomer copolymer (B) is used in the above ratio, the obtained foam layer is excellent in adhesiveness with other layers made of polyurethane, rubber, leather, etc., and is also preferable as a laminate.

Foaming agent (C)
As the foaming agent (C) used as necessary in the present invention, a chemical foaming agent, specifically, azodicarbonamide (ADCA), 1,1′-azobis (1-acetoxy-1-phenylethane), Dimethyl-2,2'-azobisbutyrate, dimethyl-2,2'-azobisisobutyrate, 2,2'-azobis (2,4,4-trimethylpentane), 1,1'-azobis (cyclohexane -1-carbonitrile), 2,2′-azobis [N- (2-carboxyethyl) -2-methyl-propionamidine] and other azo compounds; N, N′-dinitrosopentamethylenetetramine (DPT) and the like Nitroso compounds; hydrazine derivatives such as 4,4′-oxybis (benzenesulfonylhydrazide) and diphenylsulfone-3,3′-disulfonylhydrazide; semicarbazide compounds such as p-toluenesulfonyl semicarbazide; organic such as trihydrazinotriazine Thermally decomposable foaming agents, and bicarbonates such as sodium bicarbonate and ammonium bicarbonate; carbonates such as sodium carbonate and ammonium carbonate; nitrites such as ammonium nitrite; inorganic pyrolytic foaming agents such as hydrogen compounds Is mentioned. Of these, azodicarbonamide (ADCA) and sodium hydrogen carbonate are particularly preferable.

    In the present invention, physical foaming agents (foaming agents not necessarily accompanied by chemical reaction during foaming), for example, various aliphatic hydrocarbons such as methanol, ethanol, propane, butane, pentane and hexane; dichloroethane, dichloromethane, tetrachloride Various chlorohydrocarbons such as carbon; organic physical foaming agents such as various fluorinated chlorohydrocarbons such as chlorofluorocarbons, and inorganic physical foaming agents such as air, carbon dioxide, nitrogen, argon, and water. ). Among these, carbon dioxide, nitrogen, and argon are the most excellent because they do not need to be vaporized, are inexpensive, and have a very low possibility of environmental pollution and ignition.

    Since the physical foaming agent used as the foaming agent (C) in the present invention has no decomposition residue of the foaming agent, it is possible to prevent mold contamination during the crosslinking and foaming of the composition. In addition, since the physical foaming agent is not in powder form, it has excellent kneadability. In addition, when this physical foaming agent is used, it is possible to prevent off-flavors (such as ammonia odor generated during ADCA decomposition) of the resulting crosslinked foam.

    In the present invention, the chemical foaming agent as described above can be used in combination as long as no adverse effects such as odor and mold contamination occur.

    As a physical foaming agent storage method, for small-scale production, carbon dioxide, nitrogen, etc. can be used in a cylinder and supplied to an injection molding machine and an extrusion molding machine through a pressure reducing valve. In some cases, the pressure is increased by a pump or the like and supplied to an injection molding machine, an extrusion molding machine, or the like.

    In addition, if it is a facility that manufactures foamed products on a large scale, a storage tank for liquefied carbon dioxide, liquefied nitrogen, etc. is installed, passed through a heat exchanger, vaporized, piping, injection molding machine and extrusion molding machine with a pressure reducing valve Etc.

    In the case of a liquid physical foaming agent, the storage pressure is preferably in the range of 0.13 to 100 MPa. If the pressure is too low, the pressure cannot be reduced and cannot be injected into an injection molding machine or an extrusion molding machine. If it is too high, the pressure resistance strength of the storage equipment needs to be increased, which makes the equipment larger and complicated, which is not preferable. The storage pressure defined here refers to the pressure that is vaporized and supplied to the pressure reducing valve.

    When a chemical foaming agent is used as the foaming agent (C), the chemical foaming agent is used in a total amount of 100 parts by weight of the ethylene / α-olefin copolymer (A) and the ethylene / polar monomer copolymer (B). Usually, 3 to 20 parts by weight, preferably 5 to 15 parts by weight is used. However, the amount of the chemical foaming agent used can be appropriately increased or decreased depending on the target foaming ratio because the amount of generated gas varies depending on the type and grade of the foaming agent used.

    Moreover, when using a physical foaming agent as a foaming agent (C), the addition amount of a physical foaming agent is suitably determined according to the desired expansion ratio.

    In this invention, you may use a foaming adjuvant with a foaming agent (C) as needed. The foaming auxiliary agent acts to lower the decomposition temperature of the foaming agent (C), accelerate the decomposition, and make the bubbles uniform. Examples of such foaming aids include zinc oxide (ZnO), zinc stearate, salicylic acid, phthalic acid, stearic acid, oxalic acid and other organic acids, urea or derivatives thereof.

Organic peroxide (D)
Specific examples of the organic peroxide (D) used as a crosslinking agent in the present invention include dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di- (t -Butylperoxy) hexane, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexyne-3, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-bis (t- Butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butyl Examples include peroxybenzoate, t-butylperbenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, t-butylcumyl peroxide

    In the present invention, the organic peroxide (D) is usually 0.1 to 1 with respect to 100 parts by weight of the total amount of the ethylene / α-olefin copolymer (A) and the ethylene / polar monomer copolymer (B). 0.5 parts by weight, preferably 0.2 to 1.0 parts by weight. When the organic peroxide (D) is used in the above ratio, a crosslinked foam having an appropriate crosslinked structure can be obtained. Moreover, when an organic peroxide (D) is used in the above ratio together with the crosslinking assistant (E), a crosslinked foam having a more appropriate crosslinked structure can be obtained.

Crosslinking aid (E)
Specific examples of the crosslinking aid (E) used as necessary in the present invention include sulfur, p-quinone dioxime, p, p'-dibenzoylquinone dioxime, N-methyl-N-4- Peroxy crosslinking aids such as dinitrosoaniline, nitrosobenzene, diphenylguanidine, trimethylolpropane-N, N'-m-phenylenedimaleimide; or divinylbenzene, triallyl cyanurate (TAC), triallyl isocyanurate ( TAIC) is preferred. Also listed are polyfunctional methacrylate monomers such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and allyl methacrylate, and polyfunctional vinyl monomers such as vinyl butyrate and vinyl stearate. It is done. Of these, triallyl cyanurate (TAC) and triallyl isocyanurate (TAIC) are preferable.

    In the present invention, the crosslinking aid (E) as described above has a weight ratio [(E) / (D)] of the crosslinking aid (E) to the organic peroxide (D) of 1/30 to 5/1. The amount is preferably 1/20 to 3/1, more preferably 1/15 to 2/1.

Preparation of Resin Composition for Foam The resin composition for foam according to the present invention is an uncrosslinked and unfoamed composition, which may be in a molten state, or a cooled or solidified pellet or sheet. There may be.

  The pellets of the resin composition according to the present invention include, for example, the above-described ethylene / α-olefin copolymer (A), foaming agent (C), preferably ethylene / α-olefin copolymer (A), ethylene / A polar monomer copolymer (B), a foaming agent (C), and, if necessary, an organic peroxide (D), a crosslinking aid (E), and a foaming aid are mixed in a Henschel mixer or the like in the above-described proportions. -It can be melt-plasticized at a temperature at which the foaming agent (C) and / or the organic peroxide (D) is not decomposed in a kneader such as a mixer, roll, or extruder, and can be uniformly mixed and prepared by a granulator. .

    In this composition, in addition to the above-mentioned components, various additives such as fillers, heat stabilizers, weather stabilizers, flame retardants, hydrochloric acid absorbents, pigments, etc., as needed, do not impair the purpose of the present invention. It can mix | blend in the range.

    Moreover, the sheet | seat of the composition which concerns on this invention can prepare the pellet of the composition obtained as mentioned above, for example using an extruder or a calendering machine. Alternatively, the components of the composition are kneaded with a Brabender or the like, then formed into a sheet with a calender roll, formed into a sheet with a press molding machine, or kneaded with an extruder and then passed through a T die or an annular die. An uncrosslinked and unfoamed foamable sheet can be prepared by a method of converting to a non-crosslinked manner.

Foam The resin composition for foams according to the present invention comprises 0 to 50 parts by weight, preferably ethylene, of the ethylene / polar monomer copolymer (B) with respect to 100 parts by weight of the ethylene / α-olefin copolymer (A). · 5 to 30 parts by weight of ethylene / polar monomer copolymer (B), more preferably 100 parts by weight of ethylene / α-olefin copolymer (A) per 100 parts by weight of α-olefin copolymer (A) 5 to 10 parts by weight of ethylene / polar monomer copolymer (B) is included.

    The foam according to the present invention is obtained by foaming or cross-linking foaming the resin composition as described above under conditions of 130 to 200 ° C., 30 to 300 kgf / cm 2 and 10 to 90 minutes. However, since the (crosslinking) foaming time depends on the thickness of the mold, it can be appropriately increased or decreased beyond this range.

    In addition, the crosslinked foamed product according to the present invention is a molded product foamed or crosslinked and foamed under the above conditions at 130 to 200 ° C., 30 to 300 kgf / cm 2, 5 to 60 minutes, compression ratio 1.1 to 3, preferably May be a foam obtained by compression molding under conditions of 1.3-2.

    These crosslinked foams have a specific gravity (JIS K7222) of 0.13 or less, preferably 0.05 to 0.13, more preferably 0.08 to 0.13, and a surface hardness (Asker C hardness) of 45. As mentioned above, Preferably it exists in the range of 50-60. The cross-linked foam preferably has a gel fraction of 70% or more, and is usually 70 to 95%.

  Further, the tensile strength characteristic (JIS K6301-2) of the crosslinked foam according to the present invention is 2.5 MPa or more, preferably 2.7 MPa to 3.5 MPa, and the compression set is 50% or less, preferably 30 to 45. %, And the tear strength is 8.0 N / cm or more, preferably 9.0 N / cm to 12.0 N / cm.

    The cross-linked foam according to the present invention having such physical properties has characteristics such as low compression set, high tear strength, and high rebound resilience.

In addition, the said gel fraction (gel content; xylene insoluble matter) is measured as follows.
A sample of the cross-linked foam was weighed and cut into small pieces, and then the obtained pieces were put together with p-xylene in a sealed container, and p-xylene was refluxed for 3 hours under normal pressure. Next, this sample was taken out on a filter paper and allowed to dry completely. A value obtained by subtracting the weight of a xylene-insoluble component (for example, filler, filler, pigment, etc.) other than the polymer component from the weight of the dry residue is referred to as “corrected final weight (Y)”.

    On the other hand, the value obtained by subtracting the weight of the xylene-soluble component (eg, stabilizer) other than the polymer component and the weight of the xylene-insoluble component (eg, filler, filler, pigment) other than the polymer component from the weight of the sample is corrected. Initial weight (X) ”.

Here, the gel content (xylene insoluble matter) is obtained by the following formula.

Gel content [wt%] = ([corrected final weight (Y)] ÷ [corrected initial weight (X)]) × 100.

Preparation of Foam The crosslinked foam according to the present invention can be prepared, for example, by the following method. The sheet of the composition according to the present invention can be obtained by using, for example, a calendar molding machine, a press molding machine, or a T-die extruder from the mixture described in the section for preparing the composition. At the time of forming the sheet, it is necessary to form the sheet at a temperature lower than the decomposition temperature of the foaming agent (C) and the organic peroxide (D). Specifically, the temperature in the molten state of the composition is 100 to 130 ° C. It is necessary to set the conditions and form the sheet.

    The composition formed into a sheet by the above method is cut into a mold maintained at 130 to 200 ° C. in a range of 1.0 to 1.2 with respect to the volume of the mold and inserted into the mold. . A primary foam (non-cross-linked or cross-linked foam) is produced under the conditions of a mold clamping pressure of 30 to 300 kgf / cm 2 and a holding time of 10 to 90 minutes. However, since the (crosslinking) time depends on the thickness of the mold, it can be appropriately increased or decreased beyond this range.

    The shape of the (crosslinking) foaming mold is not particularly limited, but a mold having such a shape that a sheet is usually obtained is used. This mold must have a completely sealed structure so that the gas generated during decomposition of the molten resin and the foaming agent does not escape. As the mold, a mold having a taper on the inner surface is preferable from the viewpoint of resin releasability.

    The primary foam obtained by the above method is given a predetermined shape by compression molding. The compression molding conditions are such that the mold temperature is 130 to 200 ° C., the clamping pressure is 30 to 300 kgf / cm 2, the compression time is 5 to 60 minutes, and the compression ratio is 1.1 to 3.0.

    In order to obtain a crosslinked foam by a crosslinking method using ionizing radiation irradiation, first, an ethylene / α-olefin copolymer (A), and if necessary, an ethylene / polar monomer copolymer (B), and a foaming agent (C ) The organic pyrolytic foaming agent and other additives are melt-kneaded at a temperature lower than the decomposition temperature of the organic pyrolytic foaming agent, and the resulting kneaded product is molded into a sheet, for example, and foamed. Get a sex sheet.

Next, the resulting foamable sheet was irradiated with a predetermined amount of ionizing radiation to crosslink the ethylene / α-olefin copolymer (A), and if necessary, the ethylene / polar monomer copolymer (B), A foamed crosslinked sheet can be obtained by heating the foamed crosslinked sheet to a temperature equal to or higher than the decomposition temperature of the organic pyrolytic foaming agent to cause foaming. As the ionizing radiation, α rays, β rays, γ rays, electron beams, neutron rays, X rays and the like are used. Of these, cobalt-60 γ rays and electron beams are preferably used.
Examples of the product shape of the foam include a sheet shape, a thick board shape, a net shape, and a mold. From the crosslinked foam obtained as described above, a secondary crosslinked foam having the above physical properties can be prepared in the same manner as in the method for producing the secondary foam described above.

Laminate The laminate according to the present invention comprises the above-described layer composed of the crosslinked foam according to the present invention and a layer composed of at least one material selected from the group consisting of polyolefin, polyurethane, rubber, leather and artificial leather. It is the laminated body which has.

  The polyolefin, polyurethane, rubber, leather and artificial leather are not particularly limited, and conventionally known polyolefin, polyurethane, rubber, leather and artificial leather can be used. Such a laminate is particularly suitable for footwear or footwear parts.

Footwear or footwear component The footwear or footwear component according to the present invention comprises the above-mentioned crosslinked foam or laminate according to the present invention. Examples of the footwear component include a shoe sole, a shoe midsole, an inner sole, a sole, and a sandal.
[Example]
EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited at all by this Example.
It should be noted that the density, MFR, B value, Tαβ intensity ratio, molecular weight distribution (Mw / Mn) of the ethylene / 1-butene copolymer used in the examples and comparative examples, and the cross-linked foam obtained in the examples and comparative examples. The body was measured for specific gravity, compression set, tear strength, Asker C hardness (surface hardness) according to the following method.

Physical properties evaluation of ethylene / 1-butene copolymer (1) Density The density was determined at 23 ° C. according to ASTM D1505.
(2) MFR
The MFR was determined at 190 ° C. according to ASTM D1238. The measured value at 2.16 kg load was MFR2, and the measured value at 10 kg load was MFR10.
(3) B value, Tαβ intensity ratio Determined by 13C-NMR.
(4) Molecular weight distribution (Mw / Mn)
It determined with the ortho dichlorobenzene solvent and 140 degreeC by the gel permeation chromatograph.

Evaluation of physical properties and specific gravity of crosslinked foam The specific gravity of a foam on which a skin is formed (abbreviated as skin-on) was measured according to JIS K7222.
(2) Compression set According to JIS K6301, a compression set test was performed under the conditions of 50 ° C. × 6 hours and a compression amount of 50% to obtain compression set (CS).
(3) Tear strength Measured according to JIS K6301.
(4) Asker C Hardness Asker C hardness was determined at 23 ° C. and 50 ° C. according to “Spring Hardness Test Type C Test Method” described in Appendix 2 of JIS K7312-1996.
(5) Tensile strength The tensile strength was measured according to JIS K6301.

(6) Adhesive strength of laminate <Treatment of secondary cross-linked foam>
First, the secondary cross-linked foam surface was washed with water using a surfactant and dried at room temperature for 1 hour.
Next, this secondary cross-linked foam was immersed in methylcyclohexane for 3 minutes and then dried in an oven at 60 ° C. for 3 minutes. Subsequently, a UV curable primer [D-PLY T-1100, manufactured by Tosei Chemical Co., Ltd.] was applied with a thin brush, dried in an oven at 60 ° C. for 3 minutes, and then three 80 W / cm high-pressure mercury lamps were used. Using an irradiation device (manufactured by Nippon Battery Co., Ltd., EPSH-600-3S type, UV irradiation device) installed perpendicular to the passing direction, the conveyor speed is moved at a speed of 10 m / min at a position 15 cm below the light source. Irradiated with light. Subsequently, the adhesive [adhesive Bond Ace 6250 manufactured by Tosei Chemical Co., Ltd.] was thinly brushed and dried in an oven at 60 ° C. for 5 minutes. Finally, the secondary cross-linked foam coated with the adhesive and a polyurethane (PU) synthetic leather sheet subjected to the following treatment were bonded together and pressure-bonded at 20 kg / cm ² for 10 seconds.

  <Treatment of PU Synthetic Leather Sheet> The surface of the PU synthetic leather sheet was washed with methyl ethyl ketone and dried at room temperature for 1 hour. Subsequently, the adhesive [adhesive Bond Ace 6250 manufactured by Tosei Chemical Co., Ltd.] was thinly brushed and dried in an oven at 60 ° C. for 5 minutes.

  <Peeling test> The adhesive strength of the pressure-bonded sheet after 24 hours was evaluated in the following manner. That is, the pressure-bonded sheet was cut to a width of 1 cm, and the end portion was peeled off, and then the end portion was pulled in the 180-direction at a speed of 200 mm / min, and the peeled state was observed with the naked eye.

  The ethylene / polar monomer copolymer used in the examples is as follows.

(1) Ethylene / vinyl acetate copolymer (B-1)
EV460 (Mitsui / DuPont Polychemical Co., Ltd.)
Vinyl acetate content = 19% by weight
Density (ASTM D1505, 23 ° C) = 0.94g / cm3
Melt flow rate (MFR2) (ASTM D1238, load 2.16 kg, 190 ° C.) = 2.5 g / 10 min.

(2) Ethylene / methacrylic acid copolymer (B-2)
N0903HC (Mitsui / DuPont Polychemical Co., Ltd.)
Density (ASTM D1505, 23 ° C) = 0.93 g / cm3
Melt flow rate (MFR2) (ASTM D1238, load 2.16 kg, 190 ° C.) = 3 g / 10 min.

[Production Example 1]
[Preparation of catalyst solution]
18.4 mg of triphenylcarbenium (tetrakispentafluorophenyl) borate was taken and 5 ml of toluene was added and dissolved to prepare a toluene solution having a concentration of 0.004 mM / ml. [Dimethyl (t-butylamide) (tetramethyl-η5-cyclopentadienyl) silane] 1.8 mg of titanium dichloride was taken and dissolved by adding 5 ml of toluene to prepare a toluene solution having a concentration of 0.001 mM / ml. At the start of polymerization, 0.38 ml of a toluene solution of triphenylcarbenium (tetrakispentafluorophenyl) borate and a toluene solution of [dimethyl (t-butylamide) (tetramethyl-η5-cyclopentadienyl) silane] titanium dichloride were added. 0.38 ml was added, and 4.24 ml of toluene for dilution was further added, and triphenylcarbenium (tetrakispentafluorophenyl) borate was converted to 0.002 mM / L in terms of B, [dimethyl (t-butylamide) (tetramethyl [η5-cyclopentadienyl) silane] titanium dichloride was prepared in an amount of 5 ml of a toluene solution with a Ti conversion of 0.0005 mM / L.

[Preparation of ethylene / 1-butene copolymer (A-1)]
750 ml of heptane was inserted at 23 ° C. into a SUS autoclave with a stirring blade having a capacity of 1.5 liters that had been sufficiently purged with nitrogen. In this autoclave, 6 g of 1-butene and 150 ml of hydrogen were inserted while rotating a stirring blade and cooling with ice. Next, the autoclave was heated to 100 ° C. and further pressurized with ethylene so that the total pressure was 6 KG. When the internal pressure of the autoclave reached 6KG, 1.0 ml of a 1.0 mM / ml hexane solution of triisobutylaluminum (TIBA) was injected with nitrogen. Subsequently, 5 ml of the catalyst solution prepared as described above was pressed into the autoclave with nitrogen to initiate polymerization. Thereafter, the temperature of the autoclave was adjusted to an internal temperature of 100 ° C. for 5 minutes, and ethylene was directly supplied so that the pressure became 6 kg. Five minutes after the start of the polymerization, 5 ml of methanol was inserted into the autoclave by a pump to stop the polymerization, and the autoclave was depressurized to the atmospheric pressure. 3 liters of methanol was poured into the reaction solution with stirring. The resulting polymer containing the solvent was dried at 130 ° C. for 13 hours at 600 torr to obtain 12 g of ethylene / butene copolymer A1-1. Properties of the obtained ethylene / 1-butene copolymer (A-1) are shown in Table 1.

[Production Example 2]
[Preparation of ethylene / 1-butene copolymer (A-2)]
In Production Example 1, the same procedure as in Production Example 1 was carried out except that the amount of 1-butene was changed to 8 g and the amount of hydrogen was changed to 250 ml. 10 g of ethylene / 1-butene copolymer (A-2) Got. Table 2 shows the properties of the obtained ethylene / 1-butene copolymer.

[Production Example 3]
[Preparation of ethylene / 1-butene copolymer (A-3)]
In Production Example 1, except that the amount of 1-butene was changed to 10 g and the amount of hydrogen was changed to 120 ml, the same procedure as in Production Example 1 was carried out, and 10 g of ethylene / 1-butene copolymer (A-3) Got. Table 3 shows the properties of the obtained ethylene / 1-butene copolymer.

[Example 1]
100 parts by weight of ethylene / 1-butene copolymer (A-1), 3.0 parts by weight of zinc oxide, 0.75 parts by weight of dicumyl peroxide (DCP), triallyl isocyanurate (TAIC) [trade name M-60 (TAIC content 60%), Nippon Kasei Co., Ltd.] 0.10 parts by weight (as TAIC content), azodicarbonamide (trade name Binihol AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.) 4.5 parts by weight The resulting mixture was kneaded with a roll at a roll surface temperature of 120 ° C. for 10 minutes, and then formed into a sheet.

The obtained sheet was filled in a press die and pressed and heated under the conditions of 150 kg / cm ² , 155 ° C. and 30 minutes to obtain a primary crosslinked foamed body. The size of the press mold was 15 mm thick, 150 mm long, and 200 mm wide.

Next, this primary crosslinked foam was subjected to compression molding under conditions of 150 kg / cm ² and 155 ° C. for 10 minutes to obtain a secondary crosslinked foam. The size of the obtained secondary cross-linked foam was 15 mm in thickness, 160 mm in length, and 250 mm.

  Next, the specific gravity, compression set, tear strength, Asker C hardness, and tensile strength of this secondary crosslinked foamed material were measured according to the above methods. Moreover, the peeling state of the laminated body which consists of a foam and a polyurethane (PU) synthetic leather sheet was observed with the naked eye. The results are shown in Table 2.

[Example 2]
In Example 1, instead of 100 parts by weight of ethylene / 1-butene copolymer (A-1), 50 parts by weight of ethylene / 1-butene copolymer (A-1) and the following ethylene / 1-hexene copolymer were used. A secondary crosslinked foam was prepared in the same manner as in Example 1 except that the amount was changed to 50 parts by weight of the polymer (A-4), and physical properties were measured. The results are shown in Table 4.
The ethylene / 1-hexene copolymer (A-4) is manufactured by Mitsui Chemicals, Inc. and is commercially available under the trade name Evolue SP0540, and has a density (ASTM D1505, 23 ° C.) of 903 kg / m 3. Yes, 190 ° C., melt flow rate (ASTM D1238, load 2.16 kg, 190 ° C.) was 3.8 g / 10 min, and Mw / Mn was 2.2.

[Example 3]
Example 1 is the same as Example 1 except that instead of 100 parts by weight of ethylene / 1-butene copolymer (A-1), 100 parts by weight of ethylene / 1-hexene copolymer (A-4) is used. In the same manner as above, a secondary crosslinked foam was prepared and measured for physical properties. The results are shown in Table 4.

[Example 4]
In Example 1, instead of 100 parts by weight of the ethylene / 1-butene copolymer (A-1), 100 parts by weight of the following ethylene / 1-octene copolymer (A-5) was added with azodicarbonamide (product Name Binihol AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.) A secondary cross-linked foam was prepared and measured for physical properties in the same manner as in Example 1 except that 4.5 parts by weight was changed to 5.1 parts by weight. It was. The results are shown in Table 4.
The ethylene / 1-octene copolymer (A-5) is manufactured by DuPont Dow Elastomer and is commercially available under the trade name Engage 8480, and has a density (ASTM D1505, 23 ° C.) of 902 kg / m 3. 190 ° C., melt flow rate (ASTM D1238, load 2.16 kg, 190 ° C.) was 1.0 g / 10 min, and Mw / Mn was 2.1.

[Example 5]
In Example 1, instead of 100 parts by weight of the ethylene / 1-butene copolymer (A-1), 100 parts by weight of the following ethylene / 1-octene copolymer (A-6) was added with azodicarbonamide (product). Name Binihol AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.) A secondary cross-linked foam was prepared and measured for physical properties in the same manner as in Example 1 except that 4.5 parts by weight was changed to 5.1 parts by weight. It was. The results are shown in Table 4.
The ethylene / 1-octene copolymer (A-6) is manufactured by Exxon and marketed under the trade name Exact 0201, and has a density (ASTM D1505, 23 ° C.) of 902 kg / m 3, 190 ° C., melt flow rate (ASTM D1238, load 2.16 kg, 190 ° C.) was 1.0 g / 10 min, and Mw / Mn was 2.2.

[Example 6]
In Example 1, 50 parts by weight of ethylene / vinyl acetate copolymer (B-1) was added to 100 parts by weight of ethylene / 1-butene copolymer (A-1), and azodicarbonamide (trade name Binihol) was added. A secondary crosslinked foam was prepared in the same manner as in Example 1 except that 4.5 parts by weight (AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.) was changed to 4.7 parts by weight, and physical properties were measured. The results are shown in Table 4.

[Example 7]
In Example 1, 30 parts by weight of ethylene / vinyl acetate copolymer (B-1) was added to 100 parts by weight of ethylene / 1-butene copolymer (A-1), and azodicarbonamide (trade name Binihol) was added. A secondary cross-linked foam was prepared in the same manner as in Example 1 except that 4.5 parts by weight (AC # 3, manufactured by Eiwa Chemical Co., Ltd.) was changed to 4.6 parts by weight, and physical properties were measured. The results are shown in Table 4.

[Example 8]
In Example 1, 10 parts by weight of ethylene / methacrylic acid copolymer (B-2) was added to 100 parts by weight of ethylene / 1-butene copolymer (A-1), and azodicarbonamide (trade name) A secondary cross-linked foam was prepared in the same manner as in Example 1 except that 4.5 parts by weight was changed to 4.8 parts by weight (Vinihole AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.), and physical properties were measured. . The results are shown in Table 4.

[Comparative Example 1]
In Example 1, instead of 100 parts by weight of ethylene / 1-butene copolymer (A-1), 50 parts by weight of ethylene / 1-butene copolymer (A-1) and ethylene / 1-butene copolymer (A-2) Example 1 except that the amount was changed to 50 parts by weight, and 4.5 parts by weight of azodicarbonamide (trade name Binhore AC # 3, manufactured by Eiwa Chemical Industry Co., Ltd.) was changed to 4.3 parts by weight. In the same manner as above, a secondary crosslinked foam was prepared and measured for physical properties. The results are shown in Table 4.

[Comparative Example 2]
In Example 1, instead of 100 parts by weight of ethylene / 1-butene copolymer (A-1), 100 parts by weight of ethylene / vinyl acetate copolymer (B-1) was changed to azodicarbonamide (trade name). A secondary cross-linked foam was prepared in the same manner as in Example 1 except that 4.5 parts by weight was changed to 4.3 parts by weight (Vinihole AC # 3, manufactured by Eiwa Chemical Co., Ltd.), and physical properties were measured. . The results are shown in Table 4.

[Comparative Example 3]
In Example 1, instead of 100 parts by weight of ethylene / 1-butene copolymer (A-1), 100 parts by weight of ethylene / 1-butene copolymer (A-3) was changed to azodicarbonamide ( (Product name: VINYHALL AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.) A secondary cross-linked foam was prepared in the same manner as in Example 1 except that 4.5 parts by weight was changed to 4.0 parts by weight. went. The results are shown in Table 4.

[Comparative Example 4]
In Example 1, instead of 100 parts by weight of the ethylene / 1-butene copolymer (A-1), 100 parts by weight of the following ethylene / 1-hexene copolymer (A-7) was added with azodicarbonamide (product Name Binihol AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.) was changed from 4.5 parts by weight to 4.7 parts by weight, and kneaded in the same manner as in Example 1, but the ethylene / 1-hexene copolymer (A -7) did not melt, and the ethylene / 1-hexene copolymer (A-7) and the additive could not be kneaded.

  The ethylene / 1-hexene copolymer (A-7) is manufactured by Mitsui Chemicals, Inc. and is commercially available under the trade name Evolue SP2520, and the density (ASTM D1505, 23 ° C.) is 925 kg / m 3. Yes, 190 ° C., melt flow rate (ASTM D1238, load 2.16 kg, 190 ° C.) was 1.5 g / 10 min, and Mw / Mn was 3.2.

[Comparative Example 5]
In Example 1, instead of 100 parts by weight of the ethylene / 1-butene copolymer (A-1), 100 parts by weight of the following ethylene / 1-octene copolymer (A-8) was added with azodicarbonamide (product) Name Binihol AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.) A secondary cross-linked foam was prepared and measured for physical properties in the same manner as in Example 1 except that 4.5 parts by weight was changed to 4.7 parts by weight. It was. The results are shown in Table 4.

  The ethylene / 1-octene copolymer (A-8) is manufactured by DuPont Dow Elastomer and is commercially available under the trade name Engage 8200, and has a density (ASTM D1505, 23 ° C.) of 870 kg / m 3. 190 ° C., melt flow rate (ASTM D1238, load 2.16 kg, 190 ° C.) was 5.0 g / 10 min, and Mw / Mn was 2.1.

[Comparative Example 6]
In Example 1, instead of 100 parts by weight of the ethylene / 1-butene copolymer (A-1), 100 parts by weight of the following ethylene / 1-octene copolymer (A-9) was added with azodicarbonamide (product Name Binihol AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.) Foaming was performed in the same manner as in Example 1 except that 4.5 parts by weight was changed to 3.2 parts by weight, but outgassing of the foam occurred. Thus, a foam could not be obtained.
The ethylene / 1-octene copolymer (A-8) is manufactured by DuPont Dow Elastomer and is commercially available under the trade name Engage 8402, and has a density (ASTM D1505, 23 ° C.) of 902 kg / m 3. 190 ° C., melt flow rate (ASTM D1238, load 2.16 kg, 190 ° C.) was 30 g / 10 min, and Mw / Mn was 2.1.

  The cross-linked foam according to the present invention has characteristics such as low compression set, high tear strength, and high rebound resilience. Further, the crosslinked foam according to the present invention has high hardness despite its low specific gravity and excellent tensile strength characteristics, and is suitably used as footwear or footwear parts.

Claims (5)

The Asker C hardness is 45 or more, comprising a resin composition containing 100 parts by weight of an ethylene / α-olefin copolymer (A) and 0-50 parts by weight of an ethylene / polar monomer copolymer (B), and has a specific gravity (skin -On) is 0.13 or less, and a cross-linked foam characterized by a tensile strength characteristic (JIS K6301-2) of 2.5 MPa or more,
The ethylene / α-olefin copolymer (A) is an ethylene / α-olefin copolymer composed of ethylene and an α-olefin having 3 to 20 carbon atoms, and has a density (ASTM D1505, 23 ° C.) of 900 to 910 kg / m3, melt flow rate (MFR2) (ASTM D1238, load 2.16 kg, 190 ° C) at 190 ° C and 2.16 kg load is in the range of 0.1 to 10 g / 10 min, and is evaluated by the GPC method. Index of molecular weight distribution: Mw / Mn is in the range of 1.5 to 3.0. Ratio of melt flow rate (MFR10) at 190 ° C. and 10 kg load to melt flow rate (MFR2) at 190 ° C. and 2.16 kg load of ethylene / α-olefin copolymer (A):
MFR10 / MFR2 is Mw / Mn + 5.0 ≦ MFR10 / MFR2
The cross-linked foam according to claim 1, wherein A crosslinked foam obtained by secondary compression of the foam according to claim 1. A layer comprising the foam according to claim 1;
A laminate comprising a layer made of at least one material selected from the group consisting of polyolefin, polyurethane, rubber, leather and artificial leather. A footwear or a footwear component comprising the foam according to claim 1 or the laminate according to claim 4.