JP6394150B2 - Foam, laminate comprising the same, molded body and automobile interior material - Google Patents

Description

The present invention relates to a foam having both excellent moldability using polyolefin resin and mechanical strength balance such as flexibility and elongation at break.

Foams cross-linked with polyolefin resin are generally used for automobile interior materials, trays, building materials, electrical appliances, tape base materials, pipe covers, packing materials, taking advantage of lightness, cushioning, heat insulation, mechanical strength and moldability. It has been developed for various uses. Among these applications, automotive interior materials are usually sheet-like foams such as polyvinyl chloride resin sheets, thermoplastic elastomer resin sheets, natural cloths, artificial cloths, and skin materials such as leather ( Other materials) are laminated and formed into a predetermined shape by vacuum forming, compression forming or the like.

  In recent years, more complex shapes with sharp corners and softness have been required for foam molding. However, if the foaming ratio is lowered to increase the complex and sharp corner shape, the mechanical strength is increased but the flexibility is lowered, so that it becomes impossible to form a soft molded body having a complicated and sharp corner shape. Therefore, a foam for highly achieving both moldability and flexibility is desired.

Furthermore, in the molding of a foam, it is required to be soft and reduce the elongation difference at break in the width direction and the length direction. However, if the stretch ratio in the length direction during foam sheet molding is reduced to reduce the difference in elongation at break in the width direction and the length direction, the foam sheet does not travel in the center of the apparatus because the foam sheet in the length direction is too small. Wrinkle-like defects occur, and the foam cannot be supplied stably and cannot be supplied. Therefore, a foam for highly satisfying both flexibility and small difference in elongation at break in the width direction and the length direction is desired.
As a method of solving these problems, a method of adding a thermoplastic elastomer resin to a polypropylene resin and a polyethylene resin (see Patent Document 1), an ethylene block polymer that is a special thermoplastic elastomer resin, or a vinyl aromatic compound A method of adding a hydrogenated block copolymer of a block polymer and a block polymer of a conjugated diene compound to a polyolefin resin (see Patent Document 2 and Patent Document 3) has been proposed.

JP 2008-266589 A JP 2004-27119 A Japanese Patent No. 4313637

However, the method of adding a thermoplastic elastomer resin to a polyolefin resin as in the prior art described above, it is difficult to achieve a requirement that has a balance of mechanical strength such as improvement in moldability and flexibility and elongation at break. There were also limitations on the conditions of use of the resulting foam. In vacuum molding and compression molding, the processing temperature is set to a high temperature condition of 120 ° C. to 200 ° C. in order to improve productivity. In some cases, sharp corners cannot be formed, and irregularities occur on the surface, resulting in appearance defects. The thermoplastic elastomer resin has a non-crystalline portion (soft segment) having a rubber component having entropy elasticity in the molecule, so that the dimensional change rate is increased particularly under high temperature conditions.
Therefore, an object of the present invention is to solve the problems of the prior art, and to provide a foam that satisfies both the excellent moldability and flexibility at a high level and satisfies the further required performance.

  In vacuum molding, compression molding, and the like, the design dimension and the design development rate in the width direction and the length direction may be the same depending on the shape of the molding die. In the above prior art, the elongation at break on one side in the width direction and the length direction becomes small and insufficient, an extreme distortion may occur in the molded body, and the foam may be broken to cause defects in appearance. .

  The object of the present invention is to solve the problems of the prior art, to achieve both a high degree of flexibility and a small difference in elongation at break in the width direction and the length direction, and to achieve a foam satisfying increasing demanded performance. It is to provide.

The present invention for solving the above-mentioned problems is as follows.
The foam of the present invention contains a polyolefin resin and has a dimensional change rate in the thickness direction of −30% to −1% after heating at 120 ° C. for 60 minutes.
The foam of the present invention contains a polyolefin resin, and the elongation at break in the width direction and the elongation at break in the length direction are 0% <“elongation at break in the width direction” − “elongation at break in the length direction”. Degree ”≦ 80%.
According to a preferred embodiment of the foam of the present invention, the dimensional change rate in the thickness direction after including a polyolefin resin and heating at 120 ° C. for 60 minutes is −30% to −1%, and the elongation at break in the width direction is The elongation at break in the length direction is 0% <“elongation at break in the width direction” − “elongation at break in the length direction” ≦ 80%.

  According to a preferred embodiment of the foam of the present invention, the polyolefin resin contains an olefin block copolymer (A), and the olefin block copolymer (A) has an endothermic peak of 115 ° C. to 130 ° C. by a differential scanning calorimeter (DSC). The olefin block copolymer (A) has a structure in which the amorphous part and the crystalline part are connected.

  According to a preferred aspect of the foam of the present invention, the polyolefin resin includes a polypropylene resin (B) and a polyethylene resin (C).

  According to a preferred embodiment of the foam of the present invention, the gel fraction is 15% to 60%.

  According to the preferable aspect of the foam of this invention, it is a laminated body containing a foam.

  According to the preferable aspect of the foam of this invention, it is a molded object obtained from a foam.

  According to the preferable aspect of the foam of this invention, it is a motor vehicle interior material containing a foam.

According to the present invention, it is possible to form a molded body having excellent moldability and flexibility, and having a complicated shape with sharp corners. And the foam which satisfy | fills these further performance requirements is obtained.
According to the present invention, excellent flexibility, elongation at break in the width direction and elongation at break in the length direction are 0% <“elongation at break in the width direction” − “elongation at break in the length direction” A foam having a ≦ 80% and meeting these further increasing performance requirements is obtained.

  Moreover, according to this invention, the foam of the said characteristic can be manufactured and supplied stably. According to the present invention, it is possible to make use of such characteristics, and it can be suitably used for automobile interior material applications that require flexibility after molding.

The present invention has the above-mentioned problem, that is, after heating for 60 minutes in an oven set at 120 ° C. in order to be able to be molded into a complex molded article having excellent moldability and flexibility and having a sharp corner. The range of the dimensional change rate in the thickness direction of -30% to -1% is necessary. The best condition is -8% to -1%. If the rate of dimensional change in the thickness direction is -30% or less, it becomes thinner than the product-specified thickness after molding. There is a possibility that defects in appearance such as wrinkles may occur after molding due to the increase in the angle and the swelling of the corners.

  The present invention has the above-mentioned problems, that is, it has excellent moldability and flexibility, and can be molded into a molded body having a complicated shape with sharp corners. The range of the point elongation should be 0% <“Elongation at break in the width direction” − “Elongation at break in the length direction” ≦ 80%. The best condition is 0% <“elongation at break in the width direction” − “elongation at break in the length direction” ≦ 30%. If the range of elongation at break in the width direction and elongation at break in the length direction is “elongation at break in the width direction” − “elongation at break in the length direction”> 80%, Depending on the shape (width direction and length method have the same dimensions and the same expansion ratio), the mechanical strength decreases in one of the elongation at break in the width direction and the elongation at break in the length direction. May occur. When the range of the elongation at break in the width direction and the elongation at break in the length direction is “elongation at break in the width direction” − “elongation at break in the length direction” ≦ 0%, Depending on the shape (width direction and length method have the same dimensions and the same expansion ratio), the mechanical strength decreases in one of the elongation at break in the width direction and the elongation at break in the length direction. May occur.

  In this case, the width direction is a plane direction orthogonal to the length method, and the length direction is the resin extrusion direction.

  The polyolefin resin used in the present invention is such that when all the monomer components constituting the resin are 100 mol%, the olefinic hydrocarbon component in the resin is 50 mol% or more and 100 mol% or less. For example, a polypropylene resin (B) in which a propylene component is 50 mol% or more and 100 mol% or less, such as a propylene homopolymer or an ethylene-propylene copolymer (random polypropylene, block polypropylene), and an ethylene homopolymer, A polyethylene resin having an ethylene component of 50 mol% or more and 100 mol% or less, such as an ethylene-α-olefin copolymer composed of ethylene and an α-olefin having 3 to 10 carbon atoms, or a copolymer of ethylene and a non-olefin ( C).

  Further, in the present invention, there are problems in formability (dimensional change) and flexibility, or compatibility between elongation at break and flexibility, but the means is not particularly limited. However, it is preferable to use an olefin block copolymer (A) which is a thermoplastic elastomer resin composed of an α-olefin having 3 to 10 carbon atoms and ethylene.

Examples of the olefin block copolymer (A) of a thermoplastic elastomer resin comprising an α-olefin having 3 to 10 carbon atoms and ethylene include propylene, 1-butene, 1-hexene, 1-octene and 4-methyl copolymerizable with ethylene. Examples include -1-pentene, 3-methyl-1-butene, and 1-decene. The olefin block copolymer (A) exhibits rubber elasticity at room temperature, and is plasticized at high temperature to enable various molding processes. Generally, an amorphous material having a rubber component having entropy elasticity in the molecule. The part (soft segment), the molecular constraint component for preventing plastic deformation, and the crystal part (hard segment) are often shared. It does not have a wide range of three-dimensional crosslinked structure (network structure). The olefin block copolymer (A) is a special polyolefin resin having a non-crystalline part (soft segment), a molecular constraint component, and a crystalline part (hard segment) in a molecular chain.
As such an olefin block copolymer (A), for example, a block copolymer having ethylene as a soft segment, a copolymer of ethylene and a small amount of a diene or a partially crosslinked product thereof, and propylene as a hard segment. The thing which consists of coalescence etc. is mention | raise | lifted. Said olefin block copolymer (A) may be used independently, or 2 or more types may be used together. Examples of the non-olefin include vinyl acetate, vinyl alcohol, ethylene methyl acrylate, ethylene ethyl acrylate, and ethylene butyl acrylate. These polyolefin resins may be subjected to chemical modification such as grafting.

  The polyolefin resin used in the present invention can be used alone or in combination of two or more.

  The above olefin block copolymer (A), the above polypropylene resin (B), and the above polyethylene resin (C) to obtain a foam having a balance of moldability and flexibility and mechanical strength such as elongation at break. It is a particularly preferred embodiment.

The olefin block copolymer (A), the content ratio of the polypropylene resin (B) and the polyethylene resin (C) is an olefin block from the viewpoint of excellent mechanical strength balance such as moldability, flexibility and elongation at break. In a preferred embodiment, the ratio by weight of the copolymer (A) is in the range of 20% to 80%. The content range of the olefin block copolymer (A) is preferably 30 to 70% by weight, more preferably 40 to 60% by weight. The content of the olefin block copolymer (A) mentioned here is the olefin block copolymer contained in the total amount of the plurality of mixed polyolefin resin fat compositions including the olefin block copolymer (A) as 100% by weight. The weight% of (A) is said.
If the weight% of the olefin block copolymer (A) is less than 20% by weight, sufficient moldability and flexibility characteristics to be achieved by the present invention cannot be obtained. In particular, sufficient heat resistance for compression molding or the like cannot be obtained, and damage on the surface during molding may be seriously impaired.

  The polyolefin resin is an olefin block copolymer (A), a mixture of a polypropylene resin (B) and a polyethylene resin (C), and the content of the polypropylene resin (B) is preferably 10 to 50% by weight. When using what contains 50 weight% or more of (B), sufficient flexibility of polyolefin resin foam cannot be obtained, and when using what contains less than 10 weight% of polypropylene resin (B), it is obtained. There is a risk of impairing the heat resistance of the polyolefin resin foam. More preferably, it is 15 to 35%. Further, the content of the polyethylene resin (C) is preferably 10 to 30%, and when a resin containing 30% or more of the polyethylene resin (C) is used, sufficient flexibility and heat resistance cannot be obtained. When using what contains less than 10 weight% of (C), there exists a possibility of impairing the cold resistance of the polyolefin foam obtained. Preferably, it is 15 to 25% by weight.

  The olefin block copolymer (A) used in the present invention preferably has an MFR (190 ° C.) of 0.1 to 30 g / 10 minutes, more preferably 1 to 10 g / 10 minutes. If the MFR (190 ° C.) is less than 0.1 g / 10 minutes, the load on the machine during kneading may be excessive and processing may not be possible. If the MFR (190 ° C.) exceeds 30 g / 10 minutes, The mechanical strength is low and it may be insufficient as a product.

The olefin block copolymer (A) used in the present invention preferably has a density of 830 to 900 kg / m ³ , more preferably 850 to 890 kg / m ³ . If the density is less than 830 kg / m ³ , the resin is likely to be blocked and the production may be difficult, and if the density exceeds 910 kg / m ³ , the flexibility of the foam is insufficient and the object of the present invention is not fulfilled. Sometimes.

  The olefin block copolymer (A) used in the present invention preferably has an endothermic peak in the range of 115 ° C to 130 ° C, more preferably 118 ° C to 127 ° C, as measured by a differential scanning calorimeter (DSC). When the endothermic peak by the differential scanning calorimeter (DSC) is 115 ° C. or lower, or 130 ° C. or higher, the kneadability with the polypropylene resin (B) and polyethylene (C) mixed in the extruder is lowered, and the uniform cell diameter is reduced. No foam.

The olefin block copolymer (A) used in the present invention preferably has a hardness measured using a type A durometer of 30 to 70 degrees, more preferably 40 to 60 degrees. When the hardness of the type A durometer is less than 30 degrees, the mechanical strength of the foam may be low and the product may be insufficient. If the hardness of the type A durometer exceeds 70 degrees, the foam may have insufficient flexibility and may not fulfill the object of the present invention.
As an olefin block copolymer (A) used by this invention, "INFUSE" (trademark) 9507 etc. are mention | raise | lifted from Dow Chemical Company as a commercial item.

  As the polypropylene resin (B) used in the present invention, the ethylene content in 100% by mass of the polypropylene resin (B) is 5 to 15% by mass, the melting point is 135 to 155 ° C., and the MFR (230 ° C.) is 0.5 to 0.5%. The random polypropylene of 5.0 and / or the ethylene content in 100% by mass of the polypropylene resin (B) is 1-5% by mass, the melting point is 150-170 ° C., and the MFR (230 ° C.) is 1.0-7. Zero block polypropylene is particularly preferably used.

The polyethylene resin (C) has a density of 890 to 950 kg / m ³ , MFR (1
90 ° C) is preferably used in the range of 1 to 15 g / 20 minutes. Among them, the density is 920 to 940 kg / m ³ , the MFR (190 ° C) is 2 to 10 g / 10 minutes, and the melting point is 100 to 130 ° C. The ethylene-α-olefin copolymer is particularly preferably used.

  In the present invention, within the range not impairing the effects of the present invention, antioxidants such as phenols, phosphoruss, amines and sulfurs, metal damage inhibitors, divinylbenzene, trimethylolpropane trimethacrylate, 1,6 -Hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, triallyl isocyanurate, ethyl vinylbenzene, ethylene vinyl dimethacrylate, 1,2-benzenedicarboxylic acid diallyl ester, 1, Crosslinking aids such as 3-benzenedicarboxylic acid diallyl ester, 1,4-benzenedicarboxylic acid diallyl ester and 1,2,4-benzenetricarboxylic acid diallyl ester, fillers such as mica and talc, bromine-based and phosphorus-based Flame retardant, anti-trioxide Flame retardant aid such as down, antistatic agents, lubricants, pigments, and the polyolefin additives such as polytetrafluoroethylene may be added.

  The foam of the present invention is produced by mixing a polyolefin resin mixture with a foaming agent capable of generating a gas. As a method for producing the foam, a polyolefin resin mixture is used as a foaming agent. An atmospheric foaming method in which a foaming agent is added, melted and kneaded, and foamed by normal pressure heating. An extrusion foaming method and press mold in which a pyrolytic chemical foaming agent is thermally decomposed in an extruder and foamed while being extruded under high pressure. There are methods such as a press foaming method in which a pyrolytic chemical foaming agent is thermally decomposed and foamed under reduced pressure, and an extrusion foaming method in which a gas or vaporizing solvent is melt-mixed in an extruder and foamed while being extruded under high pressure. can give.

  The thermally decomposable chemical foaming agent used here is a chemical foaming agent that decomposes when heated to release a gas. For example, azodicarbonamide, N, N′-dinitrosopentamethylenetetramine, P, P Examples thereof include organic foaming agents such as' -oxybenzenesulfonylhydrazide, and inorganic foaming agents such as sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, and calcium azide.

  Examples of the gas or the solvent to be vaporized include gases such as carbon dioxide, nitrogen and helium, and vaporized solvents such as propane, normal butane and isobutane.

  A foaming agent can be used individually or in combination of 2 types or more, respectively. In order to obtain a high-magnification foam that is flexible and has high moldability and a smooth surface, a normal pressure foaming method using azodicarbonamide as a foaming agent is preferably used.

Foams of the present invention is preferably from the viewpoint of moldability and the flexibility is excellent in both an apparent density in the range of ^{30kg / m 3 ~150kg / m 3} , more preferred embodiment, 50 kg / m The range is ^{3 to} 100 kg / m ³ .
Further, in terms of the relationship between 25% compression hardness, which has a correlation with the apparent density, from the viewpoint that both formability and flexibility are excellent, 25% compression hardness (kPa) <apparent density (kg / m ³ ). More preferably, from the viewpoint of increasing flexibility, it is more preferable that 25% compression hardness (kPa) <apparent density (kg / m ³ ) −10.
When the foam of the present invention is crosslinked, that is, when the foam of the present invention is a crosslinked foam, the gel fraction indicating the crosslinked state is preferably in the range of 15% to 60%, and more preferably 30 It is preferable that it is the range of% -50%. If the gel fraction is less than 15%, the foaming agent gas is dissipated from the foaming surface, making it difficult to obtain a product with the desired expansion ratio. On the other hand, if the gel fraction exceeds 60%, excessive crosslinking occurs. It may be difficult to obtain a product with a high surface expansion ratio and a high expansion ratio, and mechanical strength such as elongation at break may be lowered, and moldability may be lowered.

  The method for crosslinking the foam of the present invention may be a conventionally known method, and the production method is not particularly limited. In the method of irradiating a sheet material with a predetermined dose of ionizing radiation to crosslink the resin, an electron beam, X-ray, β-ray, γ-ray or the like is used as the ionizing radiation. The irradiation dose is generally about 1 to 300 kGy, and the dose is set according to a desired gel fraction. In addition, a method such as crosslinking with a peroxide such as dicumyl peroxide or silane crosslinking can also be used.

  Next, the method for producing the foam of the present invention will be described by way of example.

Add a pyrolytic foaming agent such as azodicarbonamide to the olefin block copolymer (A), polypropylene resin (B), and polyethylene resin (C) and mix evenly using a mixing device such as a Henschel mixer or tumbler. To do. Then, using melt-kneading equipment such as an extruder or a pressure kneader, melt and knead uniformly below the decomposition temperature of the pyrolytic foaming agent, and after forming into a sheet shape with a T-type die, irradiate with ionizing radiation. Crosslink.
Next, the temperature of the obtained sheet is raised above the decomposition temperature of the pyrolytic foaming agent by the method of floating on a salt bath as a heat medium or the method of throwing it in an atmosphere such as hot air. The foam of the present invention can be obtained by foaming with the generated gas.

  It is preferable that the foam of this invention can be manufactured in a elongate sheet form. By making it into a long sheet shape, it is possible to supply a large amount at a low cost. Further, the foam of the present invention has a corona discharge treatment on at least one surface thereof, a coating with a skin material such as a polyvinyl chloride resin sheet or a thermoplastic elastomer resin sheet, a natural cloth, a man-made cloth, or leather. Various processes such as laminating can be performed. Also in these processes, it can be used continuously by supplying a long sheet.

  The foam of the present invention preferably has a thickness in the range of 0.5 mm to 8 mm, and more preferably in the range of 1 mm to 5 mm. If the thickness is less than 0.5 mm, the remaining thickness after molding is too thin, and there is no flexibility and a feeling of bottoming is obtained. If the thickness exceeds 8 mm, it may be difficult to form a fine design and sharpen the corners.

  The foam of the present invention preferably has a closed cell structure. In the case of a foam having a closed cell structure, it is possible to form a complicated shape, for example, air can be sufficiently drawn by vacuum forming because of the structure. Moreover, it is preferable that the bubbles are fine and uniform since the surface of the foam or a molded product obtained by molding the foam becomes smooth. Resin gelled products cause uneven defects on the foam surface and coarse bubble defects on the inside of the foam, and the defective part does not adhere in the lamination process. In the molding process, the uneven defect appears on the surface of the molded product. For example, the appearance of the final product is impaired.

  Because of the excellent moldability and flexibility, the foam of the present invention has a polyvinyl chloride resin sheet, a thermoplastic elastomer resin sheet, a natural cloth, an artificial cloth and a leather on one side of the foam. As an automotive interior material such as instrument panels and door trims, heat insulating materials such as trays, building materials, and electrical appliances, cushioning materials, tape base materials, pipe covers, and packing materials Used. In particular, it is suitably used for automotive interior material applications that require molding into a complicated and sharp shape and flexibility after processing.

  The evaluation methods used in the following examples and comparative examples are as follows.

(1) MFR of polyolefin resin:
According to JIS K7210 (Amendment 1999/10/20) "Testing methods for melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastics-thermoplastics" in JIS K7210 (revision 1999/10/20) ) Was measured at a temperature of 190 ° C., and MFR (230 ° C.) was measured at a temperature of 230 ° C. Specifically, the olefin block copolymer (A) and the polyethylene resin (C) are based on Annex B (reference) “Standards and designations of thermoplastic materials and test conditions thereof” of the above-mentioned standards. .16 kgf, polypropylene resin (B) using a melt mass flow rate meter (melt indexer model F-B01 manufactured by Toyo Seiki Co., Ltd.) under the conditions of a temperature of 230 ° C. and a load of 2.16 kgf, adopting a manual cutting method, The weight of the resin coming out of the die for 10 minutes was measured.

(2) Density of polyolefin resin:
The density of the polyolefin-based resin was measured according to JIS K7112 (Revised 1999/05/20) “Plastic—Method for measuring density and specific gravity of non-foamed plastic”.

(3) Melting point of polyolefin resin:
In the present invention, the melting point of the polyolefin resin is the maximum peak temperature obtained from the crystal melting peak of the DSC curve obtained by differential scanning calorimetry, and is a differential scanning calorimeter (DSC: RDC220-Robot manufactured by Seiko Electronics Corporation). DSC). The measurement conditions were that the sample was heated to a temperature of 200 ° C. and melted, cooled to a temperature of −50 ° C. at a rate of 10 ° C./min, and then heated at a rate of 10 ° C./min to obtain a unit mass. The per cent crystal melting energy and melting temperature were measured.

(4) Hardness of polyolefin resin:
The hardness in the present invention conforms to the method specified in JIS K6253 (1997) “Vulcanized rubber and thermoplastic rubber—How to obtain hardness”. Specifically, a test piece of olefin block copolymer (A) is prepared to a plate thickness of 6 mm using a hot press machine, etc., placed on a flat and solid surface, and the durometer A push needle is perpendicular to the test piece. Contact so as not to give a shock. After 15 seconds from the contact, the indicated value obtained is taken as the hardness.

(5) Foam thickness:
The thickness of the foam is a value measured according to ISO 1923 (Revised 1981/09/01) “Measurement method for foamed plastic and rubber linear dimensions”.

(6) Apparent density of foam:
The apparent density of the foam is a value measured in accordance with JIS K6767 (Revised 1999/10/20) “Foamed plastic-polyethylene test method”.

(7) Gel fraction of foam:
The foam is cut into about 0.5 mm squares, and about 100 mg is weighed to the nearest 0.1 mg. After being immersed in 200 ml of tetralin at a temperature of 130 ° C. for 3 hours, it is naturally filtered through a 100 mesh stainless steel wire mesh, and the insoluble matter on the wire mesh is dried in a hot air oven at 120 ° C. for 1 hour. Next, the mixture is cooled in a desiccator containing silica gel for 10 minutes, the mass of this insoluble matter is accurately weighed, and the gel fraction of the foam is calculated as a percentage according to the following formula.
Gel fraction (%) = {mass of insoluble matter (mg) / weight of weighed foam (mg)} × 100.

(8) 25% compression hardness of the foam:
The 25% compression hardness of the foam is a value measured based on JIS K6767 (1999) “Foamed plastic-polyethylene test method”. Specifically, the foam is cut into 50 mm × 50 mm, stacked so that the thickness is 20 mm or more and 30 mm or less, and the initial thickness is measured. A sample was placed on a flat plate, and stopped by compressing at a speed of 10 mm / min up to 25% of the initial thickness, the load after 20 seconds was measured, and 25% compression hardness (kPa) was calculated by the following formula.
・ 25% compression hardness (kPa) = 25% compression and 20 seconds later (N) / 25 (cm ² ) / 10.

(9) Elongation at break of foam:
The elongation at break of the foam is a value measured based on JIS K6767 (1999) “Foamed plastic-polyethylene test method”. Specifically, the polyolefin resin foam was left in an oven adjusted to 23 ° C., and the surface temperature of the polyolefin resin foam was measured with a thermo-label, and the surface temperature of the polyolefin resin foam became 23 ° C. Sometimes uniaxial tensile test. Also, the polyolefin resin foam is left in an oven adjusted to 160 ° C., and the surface temperature of the polyolefin resin foam is measured with a thermo label. When the surface temperature of the polyolefin resin foam reaches 160 ° C., uniaxial tension is applied. Test.
The following formula was used to evaluate the elongation at break of the foam, and ◎ and ○ were accepted.
A: 0% <“Elongation at break in the width direction” − “Elongation at break in the length direction” ≦ 30%.
○: 30% <“Elongation at break in the width direction” − “Elongation at break in the length direction” ≦ 80%.
×: Not applicable to either ◎ or ○.

(10) Dimensional change rate of foam:
The dimensional change rate of the foam is a value measured based on JIS K6767 (1999) “Foamed plastic-polyethylene test method”. Specifically, the polyolefin resin foam is accurately cut into a 15 cm square and left in an oven set at 120 ° C. for 60 minutes. After 60 minutes, remove from the oven and cool at room temperature for about 30-60 minutes. The dimensions of the sample were measured, and the dimensional change rate was calculated as a percentage based on the following formula.
Heating dimensional change rate (%) = [{sample length before putting into oven−sample length after taking out from oven} / sample length before putting into oven] × 100
From the value of the calculation formula for the heating dimensional change rate, the following evaluation was made, and ◎ and ○ were accepted.
(Double-circle): The heating dimensional change rate is -1% to -8%.
○: The heating dimensional change rate is −30% or more and less than −8%.
×: Not applicable to either ◎ or ○.

(11) Evaluation method of flexibility of foam:
Regarding the flexibility, the flexibility of the foam was evaluated from the 25% compression hardness of the foam and the apparent density of the foam using the following calculation formula, and ◎ and ○ were accepted.
A: 25% compression hardness (kPa) <apparent density (kg / m ³ ) −10.
○: 25% compression hardness (kPa) ≧ apparent density (kg / m ³ ) −10 and 25% compression hardness (kPa) <2.0 × apparent density (kg / m ³ ).
×: Not applicable to either ◎ or ○.

(12) Heat molding processability:
The heat molding processability was evaluated by the molding drawing ratio H / D at the time of vacuum molding. In a vertical cylindrical female cup with a diameter of D and a depth of H, when the foam was heated and straight molded using a vacuum molding machine, the foam expanded and expanded without tearing. This was done by comparing the values with the largest H / D values. The diameter D used the cup of 50 mm, measured the shaping | molding drawing ratio when the surface temperature of a foam is 170 degreeC, it was set as the following evaluation from the value, and (double-circle) and (circle) were set as the pass.
A: Molding ratio is 0.7 or more. B: Molding ratio is 0.5 or more and less than 0.70. X: Molding ratio is less than 0.5.

(13) Sharpness by angle R:
The foam having a molding drawing ratio of 0.5 or more molded after the heat molding process of (12) was shredded in the product thickness direction, and the cross-sectional shape thereof was photographed with a microwatcher. The outer periphery of the circle was overlaid on the corner of the photograph, and the following evaluation was made based on the radius of the circle.
A: The radius of the circle is less than 3 mm. A: The radius of the circle is 3 mm or more and less than 8 mm. X: The circle radius is 8 mm or more.

Resins used in Examples and Comparative Examples are as follows.
Olefin block copolymer (A) A-1: “INFUSE” (registered trademark) 9507 manufactured by Dow Chemical Company, density: 867 kg / m ³ , MFR = 5.0 g / 10 min, melting point = 119 ° C.

Olefin block copolymer (A) A-2: “Tafmer” (registered trademark) PN-2070 manufactured by Mitsui Chemicals, density: 867 kg / m ³ , MFR = 7.0 g / 10 min, melting point = 140 ° C.

Olefin block copolymer (A) A-3: “Tafmer” (registered trademark) DF-840 manufactured by Mitsui Chemicals, density: 885 kg / m ³ , MFR = 3.6 g / 10 min, melting point = 66 ° C.

Olefin block copolymer (A) A-4: “DYNARON” (registered trademark) 6200P manufactured by JSR, density: 880 kg / m ³ , MFR = 2.5 g / 10 min, melting point = 140 ° C.

Olefin block copolymer (A) A-5: “DYNARON” (registered trademark) 4600P manufactured by JSR, density: 910 kg / m ³ , MFR = 5.5 g / 10 min, melting point = 98 ° C.

Polypropylene resin (B) B-1: “NOVATEC PP” (registered trademark) EG6D manufactured by Nippon Polypro, density: 900 kg / m ³ MFR = 1.9 g / 10 min, melting point = 139 ° C.

Polypropylene resin (B) B-2: “Prime Polypro” (registered trademark) J452HAP manufactured by Prime Polymer (B) Prime Polymer, density: 900 kg / m ^3, MFR = 3.5 g / 10 min, melting point = 163 ° C.

Polyethylene resin (C) C-1: Polyethylene resin (C) “Novatec” (registered trademark) LL UJ960 made by Nippon Polyethylene, density: 935 kg / m ³ , MFR = 5 g / 10 min, melting point = 126 ° C.

Polyethylene resin (C) C-2: Polyethylene resin (C) Prime polymer “Evolue” (registered trademark) SPO, density: 903 kg / m ³ , MFR = 3.8 g / 10 min, melting point = 117 ° C.

  Foaming agent: “Binihol AC # R” (registered trademark) manufactured by Azodicarbonamide Eiwa Chemical Industries.

  Crosslinking aid: 55% divinylbenzene manufactured by Wako Pure Chemical Industries.

  Antioxidant: “IRGANOX” (registered trademark) 1010 manufactured by BASF Corporation.

The foams produced in Examples 1 to 18 and Comparative Examples 1 to 4 are as follows.
Mixing was performed using a Henschel mixer at the ratio shown in Table 1, and melt extrusion was performed at a temperature of 170 ° C. using an extruder, and a polyolefin resin sheet having a thickness of 1.5 mm was prepared using a T die. The polyolefin-based resin sheet thus obtained was irradiated with an electron beam with acceleration voltage of 800 kV and 60 kGy from one side to obtain a crosslinked sheet, and then the crosslinked sheet was floated on a salt bath at a temperature of 220 ° C. And heated with an infrared heater to cause foaming. The foam is cooled with water at a temperature of 60 ° C., the foam surface is washed with water and dried, the thickness is 1.9 to 2.3 mm, the apparent density is 35 to 160 kg / m ³ , and the gel fraction is 35. A long roll of ~ 45% foam was obtained. The evaluation results of this foam are shown in Table 1.

(Example 19)
A laminate obtained by thermally laminating a 0.3 mm TPO (thermopolyolefin) skin on the foam obtained in Example 5 was obtained. As a result of carrying out heat molding processing on the obtained laminate, the measured values were a molding drawing ratio: 0.6 or more, an angle R: 5 mm, and sufficient angular sharpness was obtained.

Claims (7)

Including polyolefin resin,
Density of 30~150kg / ^{m 3,} a thickness direction of the dimensional change rate of Ru -30%-1% der foam after heating 60 minutes at 120 ° C.,
The polyolefin resin includes an olefin block copolymer (A), a polypropylene resin (B), and a polyethylene resin (C), and the density of the polyethylene resin (C) is in the range of 890 to 950 kg / m ^3. Foam. 2. The foam according to claim 1, wherein the gel fraction is 15% to 60%. The foam according to claim 1 or 2, wherein the elongation at break in the width direction and the elongation at break in the length direction satisfy the following relational expression.
0% <“Elongation at break in the width direction” − “Elongation at break in the length direction” ≦ 80% The olefin block copolymer (A) has an endothermic peak by a differential scanning calorimeter (DSC) in the range of 115 ° C to 130 ° C,
The foam according to any one of claims 1 to 3, wherein the olefin block copolymer (A) has a structure in which an amorphous part and a crystalline part are connected. The laminated body containing the foam in any one of Claims 1-4 . The molded object obtained from the foam in any one of Claims 1-4 . The automotive interior material containing the foam in any one of Claims 1-4 .