JPH02255739A - Continuous sheet of crosslinked foamed material - Google Patents

Abstract

PURPOSE:To obtain the title foamed product which has specific physical properties and excellent elastic recovery, moldability and heat resistance by using a specific block copolymer, a polypropylene resin and a polyethylene resin in a specific proportion. CONSTITUTION:The subject foamed product is composed of (A) 10 to 55wt.% of a block copolymer which is composed of a styrene polymer at the blocks on both chain ends and of an ethylene-butylene copolymer or ethylene-propylene copolymer, preferably of 20,000 to 350,000 molecular weight at the center block, (B) 40 to 85wt.% of a polypropylene resin, preferably a random copolymer thereof with 2 to 15wt.% of ethylene, and (C) 5 to 40wt.% of a polyethylene resin such as ethylene-vinyl acetate copolymer wherein 25% compression hardness is 0.8 to 1.8 kg/cm<2>, the stress at 5% elongation is 5 to 50kg/cm<2>, elasticity recovery is less than 10%, moldability L/D (L is the depth of molded product and D is the diameter) is 0.3 to 1.0 and thermal dimensional change is less than 5% at 120 deg.C.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a continuous sheet-like crosslinked foam, in particular, a continuous sheet-like crosslinked foam, in particular, a continuous sheet-like crosslinked foam, in which the block portions at both ends are made of a styrene polymer, and the block portion in the center is made of an ethylene-butylene copolymer or The present invention relates to a continuous sheet-like crosslinked foam made of a resin mixture composition containing a block copolymer made of an ethylene-propylene copolymer, a polypropylene resin, and a polyethylene resin.

[Conventional technology]

A foam made of a resin mixture composition containing a block copolymer made of an aromatic vinyl compound and a conjugated diene polymer, a polypropylene resin, and a polyethylene resin is described, for example, in JP-A-61-241332. There are things listed.

The resin foam described in the above publication contains 30 to 90% by weight of a block copolymer in which the block portions at both ends are made of an aromatic vinyl compound and the block portion in the center is made of a conjugated diene polymer, and 5 to 40% by weight of a polypropylene resin. % by weight and 5 to 40% by weight of a polyethylene resin. This composition range corresponds to region A in FIG.

Moreover, this resin foam is a non-crosslinkable foam.

[Problem to be solved by the invention]

The foam described in the above publication is a foam obtained by foaming a resin mixed composition using a gas injection method. Therefore, it is difficult to obtain a continuous sheet-like foam. In particular, it is difficult to obtain a sheet-like foam having the desired width, thickness, and length. Furthermore, since it is a non-crosslinked foam, it does not have sufficient heat resistance. Furthermore, since the main component is a block copolymer, emphasis is placed on elastic recovery.
Shape retention after molding is not sufficient.

An object of the present invention is to provide a continuous sheet-like crosslinked foam that has excellent elastic recovery properties, moldability, and heat resistance, and that can easily be formed into desired widths, lengths, and thicknesses. .

[Means to solve the problem]

The continuous sheet-like crosslinked foam of the present invention is a block copolymer in which the block portions at both ends are made of a styrene polymer and the block portion in the center is made of an ethylene-butylene copolymer or an ethylene-propylene copolymer. %and,
This is a sheet-shaped crosslinked foam made of a resin mixed composition containing 40 to 85% by weight of a polypropylene resin and 5 to 40% by weight of a polyethylene resin.

Moreover, this continuous sheet-like crosslinked foam has a 25% compression hardness of 0.3 to 1.3 kg/cd and a stress at 5% elongation of 5.
~50kg/cd, elastic recovery rate 10% or less, moldability L
/D (L: depth of mold, D: diameter of mold) is 0
．． 3-1. 011 Heating dimensional change rate below 20℃ is 5%
It has the following characteristics.

The block copolymer used in the present invention is a block copolymer in which the block portions at both ends are made of a styrene polymer and the block portion in the center is made of an ethylene-butylene copolymer, or This is a block copolymer in which the block portion is made of a styrene polymer and the central block portion is made of an ethylene-propylene copolymer. The block copolymer is obtained by hydrogenating a block copolymer in which the block portions at both ends are made of a styrene copolymer and the block portion in the center is made of butadiene and/or isoprene to reduce diene bonds.

When the central block portion is butadiene, a block copolymer in which the central block portion is composed of an ethylene-butylene copolymer can be obtained by hydrogenation. The structural formula of this block copolymer is as follows.

When the central block part is isoprene, a block copolymer in which the central block part is an ethylene-propylene copolymer can be obtained by hydrogenation. The structural formula of this block copolymer is as follows.

In addition, in each of the above structural formulas, k/(m+n) of each block copolymer is (15 to 25)/(85 to 75).
It is desirable that the polymer be polymerized so that

The molecular weight of the block copolymer is preferably 10,000 to 500,000, more preferably 20,000 to 350,000. When the molecular weight is less than 10,000, the mechanical strength of the foam decreases.

On the other hand, when the molecular weight exceeds 500,000, the melt viscosity is so high that the resin mixture composition described below may foam before being processed into a foamable sheet.

The block copolymers may be used alone or in combination of two or more.

A particularly desirable block copolymer for use in the present invention is a block copolymer in which the block portions at both ends are made of a styrene polymer and the block portion in the center is made of an ethylene-butylene copolymer. When this block copolymer is used, the extrudability and flexibility of the foam are particularly good.

Polypropylene 7, resin The polypropylene resin used in the present invention contains ethylene and/or α having 4 to 8 carbon atoms relative to propylene.
2 to 35% by weight copolymerization of olefin, and/
Or a propylene homopolymer. The copolymerization type of the copolymer consisting of propylene and ethylene and/or α-olefin may be random copolymerization, block copolymerization, or random block copolymerization, but 2 to 15 percent by weight tyrene may be used. It is desirable to use a copolymerized random copolymer.

The intrinsic viscosity of the polypropylene resin used in the present invention is preferably 1.6 to 2.5, more preferably 1.8 to 2°2.

If the viscosity is less than 1.6, the basic properties of the resin will deteriorate, and elongation and impact resistance will decrease. On the other hand, if the viscosity is greater than 2.5, the melting characteristics of the resin will be high, and the blowing agent will easily decompose during the production of a foamable sheet.

Examples of polyethylene resins used in the present invention include vinyl esters, acrylic acid, methacrylic acid, acrylic acid alkyl esters such as methyl acrylate-ethyl acrylate, methyl methacrylate, and ethyl methacrylate. Examples include methacrylic acid alkyl esters such as methacrylic acid alkyl esters, and copolymers of ethylene and copolymer components such as maleic anhydride. The above copolymerization components may be used not only one type but two or more types. The copolymerization component is preferably contained in an amount of 5 to 30% by weight based on ethylene.

Such polyethylene resins include ethylene-vinyl acetate copolymers containing 8 to 20 percent by weight of vinyl acetate, ethylene-acrylic acid copolymers containing 3 to 15 percent by weight of acrylic acid, Methyl acrylate 5-2
Ethylene-ethyl acrylate copolymer containing 5% by weight, anhydrous? Ethylene-maleic anhydride-methyl methacrylate copolymer containing 3 to 8% by weight of L/inic acid and 5 to 15% by weight of methyl methacrylate, and 3 to 15% by weight of acrylic acid. and an ethylene-ethyl acrylate-acrylic acid copolymer containing 1 to 5% by weight of ethyl acrylate, and an ethylene-ethyl acrylate-acrylic acid copolymer containing 3 to 8% by weight of maleic anhydride and 5 to 5% by weight of ethyl acrylate.
An example is an ethylene-maleic anhydride-ethyl acrylate copolymer containing 15% by weight. Particularly desirable among the above copolymers are copolymers containing acrylic acid or ethyl acrylate as a copolymerization component. A foam using a polyethylene resin made of this copolymer has good flexibility and adhesiveness.

Note that the polyethylene resin may be obtained by graft copolymerizing the above copolymer with a copolymer component.

The resin mixture composition used in the present invention is a resin mixture composition containing the block copolymer, a polypropylene resin, and a polyethylene resin.

This resin mixed composition contains 10% of the block copolymer.
~55% by weight (preferably 20~50% by weight), and the polypropylene resin accounts for 40~85% by weight (preferably 4% by weight).
5-8031i1%), the polyethylene resin is 5-8031i1%)
It is contained in an amount of 40% by weight (preferably 10 to 30% by weight). This composition range corresponds to region B in FIG.

When the block copolymer content is 10% by weight or less, the flexibility and elastic recovery properties of the foam deteriorate. On the other hand, if the block copolymer content exceeds 55% by weight, the heat resistance of the foam may deteriorate and the foam may undergo molding shrinkage immediately after molding. In addition, polypropylene resin is 40%
If it is less than % by weight, the heat resistance and mechanical strength of the foam will decrease. Conversely, polypropylene resin is 85% by weight.
If it exceeds this, the flexibility of the foam will decrease. Furthermore, when the polyethylene resin is less than 5% by weight, the compatibility between the block copolymer and the polypropylene resin decreases, and the flexibility of the foam also decreases.

On the other hand, if the content of the polyethylene resin exceeds 40% by weight, the heat resistance of the foam will decrease.

In addition to the above-mentioned resin components, the resin mixture composition used in the present invention includes inorganic fillers such as calcium carbonate, talc, glass balloons, and shredded glass fibers, antioxidants, antistatic agents,
Flame retardants, colorants, etc. may also be added. The additive is
It is added to the resin mixture composition within a range that does not impair the purpose of the present invention.

゛C゛The continuous sheet-like crosslinked foam of the present invention is obtained by crosslinking the resin mixture composition and foam-molding it into a sheet having a desired width and thickness.

The 25% compression hardness of the continuous sheet crosslinked foam of the present invention is:
It is 0.3 to 1.5 kg/cd. This value is 0.3kg
If it is less than /ctA, the foam loses its stiffness, the handling properties deteriorate, and the foam feels like it is bottoming out. Conversely, this value is 1. When it exceeds 5 kg/Cta, it becomes a so-called hard foam and its cushioning properties decrease.

Note that the 25% compression hardness is a value measured according to JISK-6767.

The stress at 5% elongation of the continuous sheet-like crosslinked foam of the present invention is 5 to 50 kg/cd. If this value is less than 5 kg/ci, elastic recovery properties will be poor. Conversely, this value is 50k
If it exceeds g/c+fl, it becomes a so-called hard foam and its cushioning properties decrease.

The stress at 5% elongation is a value measured as follows. A sample piece having a width of 11 cm and a length of 10 cm is cut out from the foam, and the thickness t (cm) of this foam is measured. Then, this sample piece was attached to a tensilon type tensile tester with a chuck interval of 5 cm, and pulled at a speed of 20 an/min. At this time, the stress change occurring in the sample piece is recorded on a recording paper, and the tensile stress S, Ckg> when the sample piece is stretched by 5% is determined. From this value, the stress at 5% elongation is determined using the following formula.

Stress at 5% elongation (kg/cJ) = S l/ (I
X t ) The elastic recovery rate of the continuous sheet-like crosslinked foam of the present invention is 10% or less. If this value exceeds 10%,
Restorability against stretching and contraction, especially resilience against elongation, decreases.

The elastic recovery rate is a value measured as follows. A sample piece with a width of IC11 and a length of 10 cm was cut out from the foam.
It is attached to a Tensilon type tensile tester with the chuck interval set to 5CEl. The sample piece is then pulled at a pulling speed of 200 g+/min to measure hysteresis.

The degree of elongation at this time is 75%. Then, the amount of strain H (threshold) due to the elongation of the sample piece is measured from the hysteresis curve recorded on the recording paper, and the elastic recovery rate is determined from the following.

Elastic recovery rate (%) = (H15X100) The moldability L/D of the continuous sheet-like crosslinked foam of the present invention is 0. 3 to 1.0. If this value is less than 0.3, it will be difficult to mold it into a desired shape. On the other hand, if this value exceeds 1.0, the thickness of the foam will decrease significantly and the cushioning properties of the foam will decrease.

The value of moldability L/D is a value measured as follows. Using a cylindrical mold that can change the depth L (Cm) with respect to the diameter D (C1l), the sample piece was
A molded product is created by heating to 00°C and performing vacuum forming. The maximum depth L of the mold when the obtained molded product does not tear is measured, and the moldability L/D is determined using the following formula.

Formability=L/D The continuous sheet-like crosslinked foam of the present invention has a dimensional change rate of 5% or less under heating at 120°C. If this value exceeds 5%, the foam will easily deform during processing or when heat is applied to the molded product.

The heating dimensional change rate at 120° C. is a value measured as follows. A 10 cm x 10 cm square sample piece is cut out from the foam, and the thickness d (C1 m) at the center of the sample piece is measured. Then, this sample piece is placed in a hot air oven at 120° C. and heated for 1 hour. After cooling the sample piece completely,
Measure the width (X), length (Y) and thickness (Z) of the sample piece. The heating dimensional change rate in the width, length, and thickness directions is calculated from the obtained measurement values using the following formula.

Width direction heating dimensional change rate (%) - (10-X)/10X100 Length direction heating dimensional change rate (%) = (10-Y)/10X100 Thickness direction heating dimensional change rate (%) - (10-Z) /IOX100 The gel fraction of the continuous sheet-like crosslinked foam of the present invention is 10 to
60% is desirable. When the gel fraction is small, the heat resistance decreases due to insufficient crosslinking, resulting in a worsening of the heating dimensional change rate. In addition, the surface of the foam is likely to become rough. Conversely, if the gel fraction is too large, the moldability and cushioning properties of the foam will decrease.

The gel fraction is a value measured as follows.

Cut the foam and accurately weigh 0.2 g of the sample. This sample is immersed in tetralin at 130°C for 2 hours, and insoluble matter is removed and washed with acetone. Then, the sample was heated to 100°C.
After drying for 1 hour in a vacuum dryer, the weight W+ (g) is accurately weighed. From the obtained value, determine the gel fraction using the following formula.

Gel fraction (%) = (W + 10.2) x 100 The density of the continuous sheet-like crosslinked foam of the present invention is 0°02 to 0.2 g/
CD is preferable. When the density is low, it is preferable from the viewpoint of flexibility, but mechanical strength decreases. On the other hand, if the density is too high, the foam becomes a hard foam and its cushioning properties decrease.

The density is a value measured as follows. Cut out a sample piece of 10cm x lOcm square from the foam, and its thickness t
(Cm) is measured. The weight Wt (g) of this sample piece is accurately weighed, and the density is determined from the obtained value using the following formula.

A resin mixed composition is prepared by mixing a block copolymer having a density (g/d)=Wz/(10xl 0xt)c, a polypropylene resin, and a polyethylene resin within the above range. This resin mixed composition was heated at 140 to 180°C.
The mixture is melted and mixed by introducing it into a heated mixing roll or pressurized kneading machine. A well-known decomposable chemical blowing agent such as azodicarbonamide, dinitrosopentamethylenetetramine, etc. is added to the melt-mixed resin mixture composition, and the mixture is further melt-mixed. The decomposable chemical foaming agent is desirably added in an amount of 2 to 25 parts by weight per 100 parts by weight of the resin mixture composition.

Next, 1 portion of the resin mixture composition containing the decomposable chemical foaming agent was added.
The mixture is introduced into two rolls heated to 40 to 180° C. and formed into a sheet, and the obtained sheet-like resin mixture composition is further formed into square pellets.

The resulting pellets are introduced into an extruder heated to a temperature at which the decomposable chemical blowing agent does not decompose, that is, 150 to 190°C, and formed into a continuous sheet having the desired width, length, and thickness.

Subsequently, the obtained continuous sheet-shaped resin mixture composition is crosslinked. As a crosslinking method, an ionizing radiation irradiation method or a chemical crosslinking method is used. When crosslinking is carried out by a chemical crosslinking method, an organic peroxide-based chemical crosslinking agent such as dicumyl peroxide or 2,5-dimethylhexane-2,5-dimethylhydroperoxide is added to the resin mixture composition in advance. I'll keep it. Crosslinking is performed when the gel fraction of the foam is 10 to 6.
It is applied so that it becomes 0%.

Further, as a crosslinking method, a method may be used in which a vinyl silane such as vinyl methoxysilane is added to a resin mixture composition to form a graft, and then water is added and silanol condensation is utilized. Alternatively, crosslinking may be carried out by adding a photosensitizer such as hydroquinone to the resin mixture composition and irradiating it with light of a specific wavelength.

In addition, in order to perform crosslinking smoothly, the resin mixture composition contains:
Polyfunctional monomers having two or more vinyl groups, such as divinylbenzene and pentaerythritol triacrylate, and dimer trimers may be added as crosslinking aids.

The crosslinked continuous sheet-like resin mixture composition is heated to a temperature of 10 to 100°C above the decomposition temperature of the added decomposable chemical foaming agent.
Introduce into a high hot air atmosphere or onto a chemical solution such as silicone oil. By rapidly decomposing the decomposable chemical blowing agent, a continuous sheet-like crosslinked foam can be obtained.

Composite materials can be made by laminating various skin materials such as plastic films or sheets, other foams, metal foils, paper, nonwoven fabrics made of natural fibers or synthetic fibers, and vinyl leather using agents. In addition, when bonding a skin material or the like, it is desirable to subject the surface of the continuous sheet-like crosslinked foam to corona discharge treatment, flame treatment, etc. in order to improve adhesiveness.

The continuous sheet-shaped crosslinked foam of the present invention can be used alone or as a composite material for medical tape base materials, clothing cushion materials, automobile door trims, ceilings, cushioning materials such as instrument panels, and housing materials such as carpets. Used as cushioning material for lining products, frequently used materials for various packing materials, base material for various adhesive tapes, base material for automobile moldings, etc. Further, since the continuous sheet-shaped crosslinked foam of the present invention has closed cells and is excellent in airtightness, it can be used as a material for a diving wet suit or a material for cold weather gear.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a continuous sheet-like crosslinked foam that is excellent in all of elastic recovery properties, moldability, and heat resistance, and that has desired width, length, and thickness.

〔Example〕

A block copolymer in which the block portions at both ends of the tip are made of a styrene polymer and the block portion in the center is made of an ethylene-butylene copolymer (composition ratio of ethylene-butylene copolymer and styrene polymer: ethylene-butylene copolymer). Butylene/styrene = 7
5/25, molecule m: 30000) 30In1% and ethylene propylene random copolymer (ethylene content:
5% by weight, viscosity: 2.15) 60% by weight, and ethylene-
Add 10% by weight of azodicarbonamide as a decomposable chemical blowing agent to a resin mixture composition consisting of 10% by weight of ethyl acrylate copolymer (ethyl acrylate content: 18% by weight).
% by weight, 0.1 Irganox 1010 as stabilizer
% by weight and 3% by weight of calcium carbonate as a filler were mixed to prepare a foam composition. 1 of this foam composition
The mixture was sufficiently melted and kneaded using a pressure kneader at 40°C to form a sheet, and then formed into a square pellet.

The obtained pellets were melt-extruded at 160°C to prepare a sheet-like resin having a thickness of 2[IIal]. The obtained sheet-shaped resin was irradiated with ionizing radiation to undergo crosslinking treatment.

The cross-linked resin sheet was introduced onto silicone oil at 230"C and heated for 2 minutes to form a foam. The resulting foam sheet was taken out and mixed with methyl alcohol or a water-methyl alcohol mixture. Washed using.

Product evaluation of the obtained sheet-like foam was performed.

The results are shown in Table 1.

Husband opening 1 20% by weight of the block copolymer used in Example 1 and the ethylene-propylene random copolymer used in Example 1 5
0% by weight and ethylene-ethyl acrylate copolymer (
A resin mixture composition consisting of ethyl acrylate (1214% by weight) and 30% by weight, 8% by weight of abdicarbonamide as a decomposable chemical blowing agent, Irganox 101O@0.1% by weight as a stabilizer, and water as a filler. A foam composition was prepared by mixing aluminum oxide in an amount of 10% by weight. This foam composition was treated in the same manner as in Example 1 to produce a sheet-like foam. Product evaluation was performed on the obtained sheet-like foam. The results are shown in Table 1.

A block copolymer in which the block parts at both ends of the backyard main body are made of styrene polymer and the central block part is made of ethylene-butylene copolymer (composition ratio of ethylene-butylene copolymer and styrene copolymer: ethylene-butylene). /Styrene=
85/15, molecule filoo00) 30% by weight and ethylene propylene block copolymer (ethylene content: 5
% by weight, viscosity: 2.10) and 20 M% of ethylene-ethyl acrylate-maleic anhydride copolymer (contains ethyl acrylate = 8% by weight, maleic anhydride content 73% by weight) A mixed composition was created. By mixing 15% by weight of azodicarbonamide as a decomposable chemical foaming agent, 0.1% by weight of Irganox 1010 as a stabilizer, and 3% by weight of carbon black as a filler into this resin mixed composition, a foam composition was obtained. created something.

The obtained foam composition was treated in the same manner as in Example 1 to produce a sheet-like foam.

Product evaluation was performed on the obtained sheet-like foam. The results are shown in Table 1.

40% by weight of the block copolymer used in Example 1, 45% by weight of polypropylene resin (viscosity: 2.05), and ethylene-ethyl acrylate copolymer (ethyl acrylate content: 14% by weight) A resin mixed composition consisting of 15% by weight was prepared.

By mixing 13% by weight of azodicarbonamide as a decomposable chemical foaming agent, 0.1% by weight of Irganox 1010 as a stabilizer, and 10% by weight of calcium carbonate as a filler into this resin mixed composition, a composition for foaming was created. created something.

The obtained foam composition was treated in the same manner as in Example 1 to produce a sheet-like foam.

Product evaluation was performed on the obtained sheet-like foam. The results are shown in Table 1.

40% by weight of the block copolymer used in Example 1, 50% by weight of linear low density polyethylene (density 0.923 g/d), and the ethylene-ethyl acrylate copolymer used in Example 1. A resin mixed composition consisting of 10% by weight of the combined resin was prepared. This resin mixture composition is mixed with 9% by weight of azodicarbonamide as a decomposable chemical blowing agent, 0.1% by weight of Irganox 1010 as a stabilizer, and 10% by weight of calcium carbonate as a filler. A composition was created. - A sheet-like foam was created by treating the obtained foam composition in the same manner as in Example 1.

Product evaluation was performed on the obtained sheet-like foam. The results are shown in Table 1.

Comparison 1 - 60% by weight of ethylene propylene random copolymer (ethylene content: 5% by weight, viscosity: 2.15) and ethylene-vinyl acetate copolymer (vinyl acetate content: 24% by weight)
) 40% by weight. To this resin mixture composition, 6% by weight of azodicarbonamide as a decomposable chemical foaming agent, 0.1% by weight of Irganox 1010 as a stabilizer, and shredded glass fibers (diameter 3 μm, length 100 t!) as a filler were added. A foam composition was prepared by mixing 15% by weight of m).

The obtained foam composition was treated in the same manner as in Example 1 to produce a sheet-like foam.

Product evaluation was performed on the obtained sheet-like foam. The results are shown in Table 1.

50% by weight of the block copolymer used in Example 2, 30% by weight of the ethylene-propylene copolymer (however, the viscosity was 2.10) used in Example 2, and 50% by weight of the block copolymer used in Example 2. A resin mixed composition consisting of 20% by weight of ethylene-ethyl acrylate copolymer was prepared. This resin mixture composition is mixed with 13% by weight of azodicarbonamide as a decomposable chemical foaming agent, 0.1% by weight of Irganox 101O as a stabilizer, and 10% by weight of calcium carbonate as a filler. A composition was created.

The obtained foam composition was treated in the same manner as in Example 1 to produce a sheet-like foam.

Product evaluation was performed on the obtained sheet-like foam. The results are shown in Table 1.

A block copolymer in which the block parts at both ends of the block are made of a styrene polymer and the block part in the center is made of an ethylene-butylene copolymer (composition ratio of ethylene-butylene copolymer and styrene polymer: ethylene-butylene copolymer). Butylene/styrene-8
5/15, molecular 1t: 10000) 2011% and ethylene propylene random copolymer (ethylene content: 15
A resin mixed composition consisting of 60% by weight, viscosity: 1.6) and 20% by weight of the ethylene-ethyl acrylate copolymer used in Example 1 was prepared. To this resin mixture composition, 18% by weight of azodicarbonamide was added as a decomposable chemical blowing agent, and 0% of Irganox 1010 was added as a stabilizer.
．． 1% by weight, 10% aluminum hydroxide as filler
A foam composition was prepared by weight percent mixing.

The obtained foam composition was treated in the same manner as in Example 1 to produce a sheet-like foam.

Product evaluation was performed on the obtained sheet-like foam.

The results are shown in Table 1.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the mixing ratio of a resin mixture composition consisting of a block copolymer, a polypropylene resin, and a polyethylene resin constituting the continuous sheet-like crosslinked foam of the present invention and a conventional foam.

Claims (1)

[Claims] Block copolymer 1 in which the block portions at both ends are made of a styrene polymer and the block portion in the center is made of an ethylene-butylene copolymer or an ethylene-propylene copolymer.
0 to 55% by weight of a polypropylene resin, 40 to 85% by weight of a polypropylene resin, and 5 to 40% by weight of a polyethylene resin, and has a 25% compression hardness of 0.3 to 1.3 kg/cm. ^2.5%
Stress during elongation is 5 to 50 kg/cm^2, elastic recovery rate is 10% or less, and formability L/D (L: mold depth, D: mold diameter) is 0.3 to 1.0. , a continuous sheet-like crosslinked foam having a heating dimensional change rate of 5% or less at 120°C.