JP2002146075A - Polyolefin-based resin foam and polyolefin based resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crosslinked foamed molding having excellent flexibility, toughness, heat-resistance and compression property, exhibiting smooth surface and uniform cell and having high expansion ratio, and to provide a polyolefin resin composition to be used in the production of the foamed molding. SOLUTION: This polyolefin-based crosslinked and foamed molding is produced by crosslinkig and foaming of a foamable polyolefin resin composition containing a polyolefin-based resin composition and a foaming agent where the foamed molding has the following characteristics (a) to (c): (a) a gel fraction of 10-90%, (b) a swelling degree of <=30 and (c) no or only one glass transition point defined by the peak of tan δ measured by the temperature dependency of dynamic viscoelasticity measured at a frequency of 10 Hz and a ratio αof storage elastic modulus at 0 deg.C (E'0) to storage elastic modulus at 100 deg.C (E'100) (α=logE'0/logE'100) of 10-30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a crosslinked polyolefin foam and a polyolefin resin composition used for the same. More specifically, the present invention relates to a crosslinked polyolefin foam usable for automotive interior materials, architectural heat insulating materials, industrial materials, and furniture. More specifically, the present invention relates to a crosslinked foamed article having excellent flexibility, toughness, heat resistance, and compression properties, a smooth surface, uniform cells, and a high expansion ratio.

[0002]

2. Description of the Related Art Polyethylene cross-linked foams are processed into various shapes because of their excellent flexibility, light weight, heat insulation, sound insulation, and the like. It is used in a wide range of fields, such as packing materials and bath mats.

Conventionally, various methods have been known for producing a cross-linked foam of a polyolefin resin. For example, a block foam using a polyethylene resin is obtained by adding a peroxide to a polyethylene and decomposing foam. The agents are kneaded under conditions that do not cause decomposition of both, to form a crosslinkable foamable resin composition. For example, (a) the crosslinkable foamable composition is charged into a mold in a press, and heated under pressure. One-stage pressure foaming method in which a foam is formed by gradual pressure, or (b) the crosslinkable foamable composition is heated in a closed mold under pressure to partially decompose the foaming agent and depressurize to intermediate foaming It is produced by a two-stage foaming method comprising a first step of obtaining a body and a second step of heating the intermediate foam under normal pressure to decompose the remaining foaming agent. In the one-stage pressurized foaming, the polymer expands instantaneously when the pressure is released, so that the polymer is easily deformed.
It is used to form double foams. On the other hand, according to the two-stage foaming method, the production cycle is longer and the production cost is higher than in the one-stage foaming method, but there is an advantage that a highly foamed product with an expansion ratio of about 30 times can be obtained.

Further, a method of mixing a polyolefin resin with a pyrolytic foaming agent, forming the mixture into a sheet, and then irradiating ionizing radiation to crosslink and heat to crosslink and foam the polyolefin resin. An organic peroxide having a decomposition temperature lower than the decomposition temperature of the agent and the foaming agent is mixed and formed into a sheet, and then heated to decompose the organic peroxide to crosslink and then decompose the foaming agent. A method of crosslinking and foaming is also known. The polyolefin-based resin foam produced by such a method is excellent in flexibility and heat insulation, and is used for various cushioning materials and heat insulation materials. As the polyolefin resin used for these foam moldings, it is easy to set the gel fraction,
Low-density polyethylene (hereinafter referred to as LDPE) produced by a high-pressure radical polymerization method in which foam molding conditions are easily set is mainly used. However, the conventional L
DPE has a large variation in molecular weight distribution, and it has not been easy to stably produce a crosslinked foam having a constant quality.
Further, the obtained foam had low strength, and the rigidity of the foam could not be arbitrarily controlled.

On the other hand, in order to easily control the degree of crosslinking and obtain a foam having improved toughness and flexibility, LDPE is used.
Ethylene-α-olefin copolymer (hereinafter LLDP)
Notation E. ) Is also used.

Further, Japanese Patent Application Laid-Open No. Hei 7-188442 discloses that LLDPE having a narrow molecular weight distribution by using a metallocene compound as a polymerization catalyst to make α-olefin as a copolymer component uniformly present in the molecular chain. It has been proposed for use as a foam.

[0007]

SUMMARY OF THE INVENTION However, LDPE
The cross-linked foam produced by using has a problem that the breaking strength is low and the flexibility cannot be freely set.

Further, in order to impart toughness and flexibility to the foam, the cross-linking foaming using LLDPE has an expansion ratio due to processing problems such as an excessively high gel fraction and incapable of two-stage foaming. Has only a low foam,
There is a problem that the foam molding range is also very narrow, and there are many problems from the viewpoint of workability.

Further, in the method of blending LLDPE with LDPE, control of the degree of crosslinking, toughness and flexibility are somewhat improved, but the amount of LDPE added must be 50% or more. At present, the improvement effect is not at a satisfactory level.

[0010] In the method proposed in JP-A-7-188442, too, the gel fraction, which is a problem of LLDPE obtained by using a conventional Ziegler catalyst, becomes too high, the expansion ratio is low, and the high expansion molding is performed. However, the problem that the range of foam molding becomes very narrow, such as the inability to perform two-stage foam molding, which is indispensable to the above, remains unresolved and still remains.

An object of the present invention is to solve such problems, that is, to propose a crosslinked foam having excellent rigidity and heat resistance and which can be used in fields such as building materials and automobile interiors. .

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a foam having a specific property has been obtained in addition to the excellent properties of a conventional polyethylene-based crosslinked foam. Flexibility, toughness and dimensional stability, heat resistance,
Polyolefin-based cross-linking that has compressive properties, has a smooth surface, uniform cells, and is a foam with a high expansion ratio, so it can be suitably used for automotive interior materials or building materials that require heat resistance and rigidity The inventors have found that a foam can be obtained, and have accomplished the present invention. That is, the polyolefin-based crosslinked foam of the present invention is a polyolefin-based crosslinked foam obtained by subjecting a foaming resin composition containing a polyolefin-based resin and a foaming agent to cross-foaming molding, and comprises the following (a) to (c) ). (A) Immediately after P-xylene extraction at 120 ° C. for 24 hours, the gel fraction represented by the residual amount after drying at 80 ° C. and 10 mmHg for 24 hours is 10 to 90%, and (b) Formula (1) Swelling degree is 30 or less

[0013]

(Equation 2) (C) When the glass transition point obtained from the temperature dependence of dynamic viscoelasticity is expressed as a tan δ peak obtained when dynamic viscoelasticity is measured at a frequency of 10 Hz, the peak is observed. Has one glass transition point if not observed, and has a storage modulus at 0 ° C. (E ′ ₀ )
And the ratio α (α) of the storage elastic modulus (E ′ ₁₀₀ ) at 100 ° C.
_{= LogE '0 / logE' 100} ) 10 to 30 also, 100 parts by weight of the polyolefin resin to a polyolefin resin composition which is low molecular weight polyolefin waxes 5-50 parts by weight, particularly density from 0.860 to 0. 970 g /
In a range of cm ³ , DSC measurement was performed with respect to 100 parts by weight of a polyolefin resin having a weight average molecular weight determined by gel permeation chromatography of 60,000 or more and a viscosity average molecular weight determined by a viscosity method of 1500 to 10,000. It has been found that an intended foam can be obtained by using a polyolefin-based resin composition containing 5 to 50 parts by weight of a low-molecular-weight polyolefin wax having a melting point in the range of 100 to 160 ° C. to complete the present invention. Reached.

Hereinafter, the present invention will be described in more detail.

The foam of the present invention is a cross-linked polyolefin foam obtained by subjecting a foam-forming resin composition containing a polyolefin resin composition and a foaming agent to cross-foam molding. Immediately after the P-xylene extraction, the gel fraction represented by the residual amount after drying at 80 ° C. and 10 mmHg for 24 hours is 10 to 90%, preferably 15 to 70%, and the swelling degree represented by the formula (1) is 30. Less than,
Preferably 15 to 30, when the glass transition point obtained from the temperature dependence of dynamic viscoelasticity is expressed as a tan δ peak obtained when performing dynamic viscoelasticity measurement at a frequency of 10 Hz, If a peak is not observed or is observed, it has one glass transition point, and the ratio α (α = log E ′) of the storage modulus at 0 ° C. (E ′ ₀ ) to the storage modulus at 100 ° C. (E ′ ₁₀₀ ). ₀ / logE _'100)
Is a foam having characteristics of 10 to 30, preferably 10 to 20. If the gel fraction is less than 10%, the gas escapes from the resin during foam molding and does not form a foam. If the gel fraction exceeds 90%, the growth of bubbles is suppressed and not only a high foam is obtained, Cracks occur on the surface of the foam. Further, the swelling degree represented by the formula (1) is 30
When the ratio exceeds the above range, the dimensional change of the foam increases, and the variation in the cell diameter also increases. Further, the strength of the foam also decreases, which is not preferable. Further, when the glass transition point obtained from the temperature dependence of the dynamic viscoelasticity of the foam is expressed as a tan δ peak obtained when dynamic viscoelasticity is measured at a frequency of 10 Hz, When two or more are observed, they have a glass transition point corresponding to the peak, and only a low strength foam is obtained, which is not preferable. The ratio α (α = α) between the storage elastic modulus at 0 ° C. (E ′ ₀ ) and the storage elastic modulus at 100 ° C. (E ′ ₁₀₀ )
If (logE ′ ₀ / logE ′ ₁₀₀ ) exceeds the range of 10 to 30, there is a problem in dimensional change and heat resistance, which is not preferable.

The polyolefin resin composition used in the present invention to obtain a foam is a polyolefin resin composition comprising 5 to 50 parts by weight of a low molecular weight polyolefin wax per 100 parts by weight of the polyolefin resin, Is 0.860 to 0.970 g / cm ³
In the range, the weight average molecular weight determined by gel permeation chromatography is 100 parts by weight of a polyolefin resin having a molecular weight of 60,000 or more.
A polyolefin-based resin composition containing 5 to 50 parts by weight of a low-molecular-weight polyolefin wax having a melting point in the range of 100 to 160 ° C by SC measurement is exemplified.

The polyolefin resin used in the present invention has a density in the range of 0.860 to 0.970 g / cm ³ , preferably 0.860 to 0.945 g / cm ^{3.
In 3} , it is preferable that the polyolefin resin has a weight average molecular weight of 60,000 or more as determined by gel permeation chromatography, and any polyolefin resin belonging to this category can be used. Here, when the density of the polyolefin resin is less than 0.860 g / cm ³ , the obtained foam is not sticky, which is not preferable. The density is 0.970g
If it exceeds / cm ³ , decomposition starts when the peroxide and the foaming agent are kneaded, making it impossible to produce a uniform unfoamed compound. And, the weight average molecular weight is 6
If it is less than 0000, it is necessary to increase the amount of peroxide during molding of the foam or to increase the amount of irradiation with ionizing radiation, which undesirably deteriorates the productivity of the foam.

As the polyolefin resin used in the present invention, for example, high-density polyethylene (hereinafter referred to as H
DPE), LLDPE and the like. And, in the present invention, when used for foam molding, particularly excellent in crosslinking properties and foaming properties,
LLD which is an ethylene-α-olefin copolymer is obtained because a foam excellent in uniform cells, flexibility and toughness is obtained.
Preferably, it is PE.

When the polyolefin resin used in the present invention is LLDPE, the LLDPE may be produced by any method such as a high pressure method, a solution method and a gas phase method. A Ziegler catalyst generally comprising a solid catalyst component containing magnesium and titanium and an organoaluminum compound, an organic transition metal compound containing a cyclopentadienyl derivative, and a compound which reacts therewith to form an ionic complex; A catalyst such as a metallocene catalyst or a vanadium-based catalyst comprising an organometallic compound can be used, and the catalyst can be produced by copolymerizing ethylene and an α-olefin with the catalyst. And, as the α-olefin, for example, propylene, butene-1, hexene-1,
Octene-1, 4-methyl-pentene-1, and the like. Among them, a foam having excellent uniform foam, flexibility, and toughness can be obtained. LLDPE comprising olefins is preferred.

The polyolefin resin used in the present invention has a MFR at 190 ° C. and a load of 2160 g.
Is 0.1 to 30 g / 10 min, preferably 2 to 15 g / 1
0 minutes, the size of the die is L / D = 8 / 2.095 (m
m), and the melt tension when stretched at a stretch ratio of 50 using a capillary rheometer with a cylinder temperature of 160 ° C. is 50 to 300 mN, preferably 50 to 150 mN.
It is further preferred that N, a nonlinear parameter which is an index of strain hardening property of elongational viscosity, is 2 or more. If the MFR is less than 0.1 g / 10 minutes, the shear heat generated during kneading of the blowing agent is large, and decomposition of the blowing agent starts, so that good air bubbles cannot be obtained. On the other hand, if the MFR exceeds 30 g / 10 minutes, it is preferable in terms of kneading properties, but mechanical properties such as tensile strength and elongation may be reduced. Also, if the size is L / D =
8 / 2.095 (mm) and the cylinder temperature is 16
When the melt tension when stretched at a stretching ratio of 50 using a capillary rheometer at 0 ° C. is in the range of 50 to 300 mN, it hardly contains air at the time of melt-kneading, and uniform bubbles are formed when cross-linked and foamed. The polyolefin resin of the present invention preferably has a nonlinear parameter (λ) of 2 or more, preferably 3 or more, which is an index of elongational viscosity and strain hardening property. When the non-linear parameter (λ) is within this range, a foam having a uniform cell diameter and little variation is obtained. If it is less than 2, the strain hardening property of the elongational viscosity and the melt tension are insufficient, and especially in the two-stage foam molding method, the improvement in the magnification in the two-stage foaming step is reduced. The non-linear parameter is obtained as follows.

The value of the elongational viscosity (calculated value) in the linear region at the time tm when the elongational viscosity reaches the maximum value is defined as η1 (tm). The maximum value of elongational viscosity ηe (tm) obtained by actual measurement is expressed as η
The value obtained by dividing by 1 (tm) can be obtained as a nonlinear parameter (λ) which is an index of strain hardening of elongational viscosity. The elongational viscosity in the linear region is calculated from the dynamic shear modulus obtained separately by using Ozaki's formula (Ozaki et al., Journal of the Rheological Society of Japan, 16, p. 53 (1988)). Can be. Linear polyethylene such as LLDPE and HDPE is superior to LDPE having long-chain branches in mechanical properties such as tensile strength, but is not uniform in molding such as blow molding, vacuum molding, and inflation molding. It is known that cracking easily occurs and molding stability is poor. The problems in these molding processes often involve elongational viscosity (or melt tension), and in general, if the elongational viscosity is sufficiently high in strain hardening (if the melt tension is high enough), the moldability is high. Is known to improve.

In the foam molding, since the growth rate of the bubbles is high to some extent, it is considered that the strain hardening property of the elongational viscosity has a great influence on the foam moldability. Methods for increasing the strain hardening property (or melt tension) of elongational viscosity in linear polyethylene include methods such as LDPE blending and crosslinking with peroxides, introduction of ultrahigh molecular weight components, and introduction of long chain branches. ing. However, LDPE
Is required to blend about 30% by weight in order to increase the strain hardening property (or melt tension) of the elongational viscosity, and as a result, the mechanical properties are inevitably reduced.

Further, the density of the polyolefin resin in the present invention refers to a value determined in accordance with JIS K7676. Further, the weight average molecular weight in the present invention, using gel permeation chromatography,
It refers to a linear polyethylene conversion value measured using 1,2,4-trichlorobenzene.

The low molecular weight polyolefin wax used in the present invention has a viscosity average molecular weight of 1500 to 10000, preferably 3000 to 70, as measured by a viscosity method.
It has a melting point of 100 to 160 ° C, preferably 110 to 130 ° C, as measured by DSC, and any low-molecular-weight polyolefin wax belonging to this category can be used. Here, when the viscosity average molecular weight of the low-molecular-weight polyolefin wax is less than 1500, the low-molecular-weight polyolefin wax migrates to the surface of the foam when the foam is formed, which is not preferable. On the other hand, when the viscosity average molecular weight exceeds 10,000, the gel fraction after crosslinking the obtained polyolefin-based resin composition becomes high, and as a result, a foam having a high expansion ratio cannot be obtained. Further, the melting point of the low molecular weight polyolefin wax is 100 ° C.
If it is less than 1, the heat resistance of the foam obtained from the polyolefin resin composition is insufficient, which is not preferable. On the other hand, when the melting point exceeds 160 ° C., it becomes difficult to uniformly disperse the low-molecular-weight polyolefin wax as a polyolefin-based resin composition, and when such a composition is subjected to foam molding, the cells of the foam become rough and high foaming occurs. It is not preferable because a foam having a magnification cannot be obtained.

As the low molecular weight polyolefin wax used in the present invention, for example, olefins such as ethylene, propylene, butene-1, hexene-1, octene-1, 4-methyl-pentene-1 can be used with a catalyst such as a Ziegler catalyst. Use can be made of a homopolymerized or copolymerized one, and among them, a polyolefin-based resin composition is obtained which is particularly excellent in cross-linking properties, foaming properties, uniform cells, flexibility, and a foam excellent in toughness. To low molecular weight polyethylene waxes are particularly preferred.

The viscosity-average molecular weight of the low-molecular-weight polyolefin wax in the present invention is a value calculated by measuring the intrinsic viscosity in a tetralin solution at 130 ° C. and calculating from the viscosity-average molecular weight formula represented by the following formula [2]. It is. [Η] = 4.60 × 10 ⁻¹ × M ^{0.725 −2−} [2] In the above formula [I], [η] represents the intrinsic viscosity, and M represents the viscosity average molecular weight.

The melting point in the present invention refers to a value measured using a DSC according to JIS K7121.

The polyolefin resin composition of the present invention comprises:
The low-molecular-weight polyolefin wax is 5 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the polyolefin resin. When the amount of the low molecular weight polyolefin wax is less than 5 parts by weight,
When the obtained polyolefin-based resin composition is subjected to foam molding, the molding process range is narrow and the improvement effect is small. On the other hand, when the addition amount exceeds 50 parts by weight, the breaking strength and elongation when the obtained polyolefin-based resin composition is formed into a foam are undesirably reduced.

The polyolefin resin composition of the present invention comprises:
Suitable for foam molding, it is possible to form a foam having excellent uniform foam, flexibility and toughness by various known foam molding methods, and such a foam has a foaming ratio of 2 times or more. Preferably, it is a foam.

As a method for cross-linking and foaming the polyolefin resin composition of the present invention, for example, a polyolefin resin composition is mixed with a pyrolytic foaming agent and an organic peroxide, and then molded and heated to form an organic compound. A peroxide cross-linking foaming method in which peroxide is decomposed and cross-linked, and then a pyrolysis-type foaming agent is decomposed and cross-linked and foamed. An ionizing radiation crosslinking / foaming method in which radiation is applied for crosslinking and heating and crosslinking / foaming is performed.

Here, as the peroxide crosslinking foaming method, a polyolefin resin composition of the present invention is prepared by adding a thermally decomposable foaming agent, an organic peroxide as a crosslinking agent, a foaming aid if necessary, and a filler. And a temperature at which a pyrolytic foaming agent and an organic peroxide are not decomposed by a mixing roll, a kneader, an extruder, or the like, which is heated, for example, 125 ° C.
Knead at 135 ° C. Next, the obtained composition is filled in a mold, heated at 140 to 170 ° C. under pressure for a certain period of time to completely decompose the pyrolytic foaming agent and the organic peroxide, and depressurize the foam. Can be obtained.

As the organic peroxide, for example, hydroperoxides, dialkyl peroxides, peroxyesters and the like can be used. Among them, those having a decomposition temperature giving a half-life of 1 minute exceeding 90 ° C. are preferred. Such as dicumyl peroxide, t-butyl hydroperoxide, 1,3
-Bis (t-butylperoxyisopropyl) benzene, di-t-butyl peroxide, 2,5-di (t-
Butylperoxy) hexane, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne, 2,5-dimethyl-2,5-
Di (t-butylperoxy) hexane, di-t-butylperoxyphthalate and the like. These additives are added in an amount of 0.1 to 100 parts by weight of the polyolefin resin.
The range is preferably from 3.0 to 3.0 parts by weight.

As the ionizing radiation crosslinking foaming method,
To the polyolefin resin composition of the present invention, a pyrolytic foaming agent, and if necessary, a foaming aid, a filler and a pigment are added, and a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader mixer, a roll, etc. Using a general-purpose kneading device, a temperature lower than the decomposition temperature of the pyrolytic foaming agent, for example, 165 to 180
The mixture is melted and kneaded at a temperature of ° C. and formed into a sheet to form a foamable sheet. Then, the foamable sheet is irradiated with ionizing radiation to crosslink the polyolefin resin constituting the foamable sheet. As the ionizing radiation at that time, for example, electron beams, X-rays, β-rays, γ-rays, etc. of high energy (high voltage and high transparency) conventionally used for crosslinking of synthetic resins can be used. The irradiation dose at that time is generally adjusted in the range of 1 to 20 Mrad so that the degree of crosslinking (gel fraction) is 10 to 90% by weight. Further, the obtained polyolefin resin crosslinked foamable sheet,
A crosslinked foamed sheet can be obtained by heating the resin to a temperature of at least the melting temperature, preferably at least 190 ° C. As a foaming method at that time, a known method usually used, for example, a heating foaming method using hot air, infrared rays, a metal bath, an oil bath, or the like can be used.

Here, the thermal decomposition type foaming agent is not particularly limited as long as it decomposes upon heating and melting the polyolefin resin to generate gas, and a general organic or inorganic chemical foaming agent can be used. For example, azodicarbonamide,
Azo compounds such as 2,2'-azobisisobutyronitrile, azohexahydrobenzonitrile, diazoaminobenzene; benzenesulfonylhydrazide, benzene-1,
3-sulfonyl hydrazide, diphenyl sulfone-3,
Sulfonyl hydrazide compounds such as 3'-disulfonyl hydrazide, diphenyl oxide-4,4'-disulfonyl hydrazide, 4,4'-oxybis (benzenesulfonyl hydrazide), paratoluenesulfonyl hydrazide; N, N'-dinitrosopentamethylene Nitroso compounds such as tetramine, N, N'-dinitroso-N, N'-dimethylphthalamide; terephthalazide, p
Azide compounds such as -t-butylbenzazide; inorganic compounds such as sodium bicarbonate, ammonium bicarbonate and ammonium carbonate; and at least one of them is used. Among them, azodicarbonamide, 4,4 '
-Oxybis (benzenesulfonyl hydrazide) is preferred. The addition amount is preferably 2 to 30 parts by weight based on 100 parts by weight of the polyolefin resin.

In this case, for the purpose of lowering the decomposition temperature of the thermal decomposition type foaming agent, a foaming accelerator or a foaming assistant may be used.
For example, inorganic salts such as zinc white, zinc nitrate, lead phthalate, lead carbonate, phosphate trichloride, and tribasic lead sulfate; metal soaps such as zinc fatty acid soap, lead fatty acid soap, and cadmium fatty acid soap; boric acid, oxalic acid And succinic acid and adipic acid; urea; ethanolamine; glucose;

On the other hand, a foaming inhibitor can be used for the purpose of raising the decomposition temperature of the thermal decomposition type foaming agent. Examples of the foaming inhibitor include maleic acid, fumaric acid, phthalic acid, maleic anhydride, phthalic anhydride and the like. Organic acids; halogenated organic acids such as stearoyl chloride and phthaloyl chloride; polyhydric alcohols such as hydroquinone; fatty acid amines; amides; oximes;
Phosphates such as phosphites; dibutyltin malate;
Tin compounds such as tin chloride and tin sulfate; and hexachloropentadiene.

The polyolefin resin composition of the present invention may further contain other optional components as long as the effects of the present invention are not significantly impaired. Examples of the optional components include ethylene-propylene copolymer. Transferring ethylene-based copolymer rubber such as coalesced rubber, ethylene-propylene-diene copolymer rubber, ethylene-butene copolymer rubber; styrene-butadiene rubber, styrene-butadiene block copolymer or a hydrogenated product thereof Can be.

Examples of the inorganic filler include fillers such as talc, calcium carbonate, clay, mica, barium sulfate, and magnesium hydroxide; flame retardants;
Conductive fillers such as metal fibers; various pigments and the like can be blended. The conventionally used crosslinked foam using LDPE has a maximum filling amount of such a filler of 100 parts with respect to 100 parts of the resin, but the polyolefin resin composition used in the present invention must be used. Thus, an effect that the maximum filling amount can be up to 150 parts can be provided.

The polyolefin-based resin composition for foam molding of the present invention is formed into various foams such as sheets and boards by a usual cross-linking foam molding method. For example, floor materials, automobile interior materials, various cushioning materials, It can be used for pipes, wire coatings, panels and the like.

[0040]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which by no means limit the present invention.

Various measuring methods in Examples and Comparative Examples are shown below.

(Gel Fraction and Swelling Degree of Crosslinked Foam) A crosslinked foam is cut and weighed at 0.5 g. 120
C., kept in 50 ml of P-xylene for 24 hours, passed through a 200-mesh wire gauze,
It was dried at 100 ° Hg for 24 hours at 0 ° C., and the extraction residue after drying under reduced pressure was calculated and determined by weight percentage. The degree of swelling was calculated from the formula (1) by measuring the residue immediately after the extraction of p-xylene at 120 ° C. for 24 hours and the residue immediately after the extraction of xylene at 120 ° C. for 24 hours.

(Measurement of Dynamic Viscoelasticity of Crosslinked Foam) Using a compression-type dynamic viscoelasticity measuring device (DVE-V4 manufactured by Rheology Co., Ltd.), it was operated in a compression mode in a temperature range of -150 ° C. to 150 ° C. Viscoelasticity (storage modulus E ', loss modulus E ",
The temperature dependence of the loss tangent (tan δ) was measured. The measurement was performed at a frequency of 10 Hz and a heating rate of 2 ° C./min. In addition, since it is difficult to accurately measure the cross-sectional area of the foam,
E ′ and E ″ were not absolute values, but were normalized by the value of E ′ at −150 ° C. for comparison.

(Measurement of Dynamic Viscoelasticity of Polyethylene Resin) Using a parallel disk type viscometer (MR-500 manufactured by Rheology Co., Ltd.), the dynamic dynamic viscoelasticity in the linear region was measured at several temperatures of 145 ° C. to 250 ° C. The frequency dependence of the viscoelasticity (storage shear modulus G ′, loss shear modulus G ″) was measured, and a composite curve of G ′ and G ″ was obtained using the temperature at which the elongational viscosity was measured as a reference temperature. Furthermore, Ozaki's formula (Ozaki et al.,
Journal of the Rheology Society of Japan, 16, p. 53 (1988))
Was used to calculate the time dependence of the elongational viscosity in the linear region.

(Measurement of Extensional Viscosity) MELTEN Rhe
Using an ometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.), the time change of elongational viscosity was measured at an elongational strain rate of 0.1 sec-1. The measurement temperature was 160 ° C. The value of the extensional viscosity (calculated value) in the linear region at the time tm at which the extensional viscosity has the maximum value is defined as η1 (tm). The value obtained by dividing the maximum value ηe (tm) of the elongational viscosity obtained by the actual measurement by η1 (tm) was determined as a nonlinear parameter (λ) as an index of strain hardening of the elongational viscosity.

(Measurement of Melt Tension) The melt tension was measured by a capillary rheometer (Capillograph manufactured by Toyo Seiki Seisaku-sho, Ltd.).
Was evaluated.

The cylinder temperature was 160 ° C. Also,
The cylinder inner diameter is 9.55mm, and the die L / D is 8 /
2.095 (mm), piston descending speed 10 mm
/ Min, and the tension when stretched at a take-up speed of 10 m / min were measured.

(Measurement of Breaking Strength of Foam and Measurement of Dimensional Change by Heating)
Measured according to SK6767.

(Restriction of Molding Method) The moldability was determined by whether or not two-stage foaming was possible after one-stage foaming.

One-stage foaming: Only one-stage foaming is possible, and two-stage foaming is not possible. None: Two-stage foaming is possible after one-stage foaming. Example 1 Density produced by metallocene catalyst = 0.998 g /
cm ³ , LLDPE having a weight average molecular weight of 69000 (manufactured by Exxon, trade name EXACT3028, MFR:
1.2 g / 10 min) 100 parts by weight of low molecular weight polyethylene wax having a viscosity average molecular weight of 4300 and a melting point of 105 ° C. (Mitsui Chemicals, trade name: Mitsui High Wax NL)
500, density: 0.920 g / cm ³ ), and 30 parts by weight were mixed and kneaded at 130 ° C. for 5 minutes using a mixing roll to obtain a polyolefin-based resin composition.

The obtained polyolefin resin composition 10
Based on 0 parts by weight, 8.0 parts by weight of dinitrosopentamethylenetetramine as a thermal decomposition type foaming agent, 8.0 parts by weight of urea as a foaming aid, and 0.5 parts by weight of dicumyl peroxide as an organic peroxide. Then, the sheet composition obtained by kneading with a mixing roll adjusted to 125 ° C.
0t × 90 × 90mm, filled in a pressurized closed mold,
After applying an external pressure of 0 kgf / cm ³ and heating at 165 ° C. for 20 minutes, the pressure was released to obtain a crosslinked polyolefin-based foam having uniform fine cells.

The obtained foam had a uniform surface and fine cells, an expansion ratio of 24, and a gel fraction of 50%.
Had. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 2 A crosslinked polyolefin foam was obtained under the same conditions as in Example 1 except that the amount of dicumyl peroxide was changed to 0.7 part by weight.

The obtained foam had a uniform surface and fine cells, an expansion ratio of 20 times, and a gel fraction of 72%.
Had. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 3 A crosslinked polyolefin foam was obtained under the same conditions as in Example 2 except that the amount of wax was changed to 10 parts by weight.

The foam obtained had a uniform surface, fine cells, an expansion ratio of 20 times, and a gel fraction of 89%.
Had. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 4 A crosslinked polyolefin-based foam was obtained under the same conditions as in Example 2 except that the amount of wax was changed to 5 parts by weight.

The obtained foam had a uniform surface and fine cells, a foaming ratio of 20 times, and a gel fraction of 80%.
Had. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 5 LLDPE having a long-chain branch in the molecule and having a density of 0.913 g / cm ³ and a weight average molecular weight of 76,000 (manufactured by Dow Chemical Co., Ltd.)
Product name Affinity PL1840, MFR: 0.9
7 g / 10 min) 100 parts by weight, low-molecular-weight polyethylene wax having a viscosity average molecular weight of 4300 and a melting point of 105 ° C. (Mitsui Chemicals, trade name: Mitsui High Wax NL50)
0, density: 0.920 g / cm ³ ) 30 parts by weight were mixed and kneaded at 130 ° C. for 5 minutes using a mixing roll to obtain a polyolefin-based resin composition.

The obtained polyolefin resin composition 10
With respect to 0 parts by weight, 16.0 parts by weight of azodicarbonamide as a thermal decomposition type foaming agent, 0.2 parts by weight of zinc stearate as a foaming accelerator, 0.3 parts by weight of zinc oxide, and dicumyl par as an organic peroxide. A sheet-like composition obtained by mixing 0.7 parts by weight of an oxide and kneading with a mixing roll adjusted to 125 ° C. is filled in a 20 t × 90 × 90 mm pressurized closed mold, and is filled with 200 kgf / cm. ^After applying an external pressure of ³ and heating at 165 ° C. for 20 minutes, the pressure was removed to obtain a crosslinked polyolefin-based foam having uniform fine cells in a one-stage foaming step of an expansion ratio of 10 ×. This foam was placed in an oven set at 165 ° C., and further heated and foamed at normal pressure for 20 minutes.

The foam obtained had a uniform surface and fine cells, an expansion ratio of 29, and a gel fraction of 82%.
Had.

Table 1 summarizes the raw material composition and resin properties, and Table 2 summarizes the properties of the foam obtained.

Example 6 Density produced by Ziegler catalyst = 0.965 g /
cm ^3, a weight average molecular weight = 88000 of HDPE (Tosoh Co., Ltd., trade name Nipolon Hard 4010, MFR: 5
g / 10 minutes) α, α as peroxides per 100 parts by weight
-200 ppm of di-tert-butyl peroxyisopropylbenzene (Nippon Oil & Fats Perbutyl-P) was added, and the mixture was melt-kneaded in a single screw extruder set at a cylinder temperature of 220 ° C. to perform peroxide treatment to reduce MFR to 1. In addition, the viscosity average molecular weight was 4300, and the melting point was 105.
° C low molecular weight polyethylene wax (Mitsui Chemicals, trade name: Mitsui High Wax NL500, density: 0.920 g)
/ Cm ³ ) 30 parts by weight were mixed and kneaded at 130 ° C. for 5 minutes using a mixing roll to obtain a polyolefin resin composition.

The obtained polyolefin resin composition 10
With respect to 0 parts by weight, 16.0 parts by weight of azodicarbonamide as a thermal decomposition type foaming agent, 0.2 parts by weight of zinc stearate as a foaming accelerator, 0.3 parts by weight of zinc oxide, and dicumyl par as an organic peroxide. A sheet-like composition obtained by mixing 0.7 part by weight of an oxide and kneading with a mixing roll adjusted to 145 ° C. is filled in a pressurized closed mold of 20 t × 90 × 90 mm, and is filled with 200 kgf / cm. ^After applying an external pressure of ³ and heating at 165 ° C. for 20 minutes, the pressure was removed to obtain a crosslinked polyolefin-based foam having uniform fine cells in a one-stage foaming step of an expansion ratio of 10 ×. This foam was placed in an oven set at 165 ° C., and further heated and foamed at normal pressure for 20 minutes.

The obtained foam had a uniform surface and fine cells, an expansion ratio of 30 times, and a gel fraction of 70%.
Had. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 7 Density Produced by Metallocene Catalyst = 0.905 g /
cm ³ , LLDPE (M
FR: 4.2 g / 10 minutes) 100 parts by weight of α, α-di-tert-butylperoxyisopropylbenzene (Perbutyl-P manufactured by NOF Corporation) as peroxide
ppm, and melt-kneaded with a single screw extruder set at a cylinder temperature of 220 ° C. to perform peroxide treatment and MFR
Was reduced to 0.8, and the viscosity average molecular weight was 430.
0, low molecular weight polyethylene wax having a melting point of 105 ° C. (manufactured by Mitsui Chemicals, trade name: Mitsui High Wax NL500,
Density: 0.920 g / cm ³ ) 30 parts by weight were blended and kneaded at 130 ° C. for 5 minutes using a mixing roll to obtain a polyolefin-based resin composition.

The obtained polyolefin resin composition 10
With respect to 0 parts by weight, 16.0 parts by weight of azodicarbonamide as a thermal decomposition type foaming agent, 0.2 parts by weight of zinc stearate as a foaming aid, 0.3 parts by weight of zinc oxide, and dicumyl par as an organic peroxide. 0.7 parts by weight of oxide
The sheet-like composition obtained by kneading with a mixing roll adjusted to 145 ° C. was filled in a pressurized closed mold of 20 t × 90 × 90 mm, and an external pressure of 200 kgf / cm ³ was applied thereto at 165 ° C. After heating for 20 minutes, the pressure was released to obtain a crosslinked polyolefin-based foam in a one-stage foaming step having a foaming ratio of 10 having uniform fine cells. 16
It was placed in an oven set at 5 ° C. and heated and foamed at normal pressure for another 20 minutes.

The foam obtained had a uniform surface and fine cells, an expansion ratio of 30 and a gel fraction of 72%.
Had. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 8 Density Produced with Metallocene Catalyst = 0.920 g /
cm ³ , weight average molecular weight = 69000 LLDPE (M
(FR: 4.2 g / 10 minutes) 100 parts by weight of α, α-di-tert-butylperoxyisopropylbenzene (Perbutyl-P manufactured by NOF Corporation) as a peroxide was added to 150 parts by weight.
ppm, and melt-kneaded with a single screw extruder set at a cylinder temperature of 220 ° C. to perform peroxide treatment and MFR
Was reduced to 1, the viscosity average molecular weight was 4300,
Low molecular weight polyethylene wax having a melting point of 105 ° C. (manufactured by Mitsui Chemicals, trade name: Mitsui High Wax NL500, density:
0.920 g / cm ³ ) 30 parts by weight were blended and kneaded at 130 ° C. for 5 minutes using a mixing roll to obtain a polyolefin resin composition.

The obtained polyolefin resin composition 10
With respect to 0 parts by weight, 16.0 parts by weight of azodicarbonamide as a thermal decomposition type foaming agent, 0.2 parts by weight of zinc stearate as a foaming aid, 0.3 parts by weight of zinc oxide, and dicumyl par as an organic peroxide. 0.7 parts by weight of oxide
The sheet-like composition obtained by kneading with a mixing roll adjusted to 145 ° C. was filled in a pressurized closed mold of 20 t × 90 × 90 mm, and an external pressure of 200 kgf / cm ³ was applied thereto at 165 ° C. After heating for 20 minutes, the pressure was released to obtain a crosslinked polyolefin-based foam in a one-stage foaming step having a foaming ratio of 10 having uniform fine cells. 16
It was placed in an oven set at 5 ° C. and heated and foamed at normal pressure for another 20 minutes.

The obtained foam had a uniform surface and fine cells, an expansion ratio of 30 and a gel fraction of 65%.
Had. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 9 Density of LLDPE produced by Ziegler catalyst =
LLDPE having a weight-average molecular weight of 0.900 g / cm ³ and a weight-average molecular weight of 85,000 (trade name: Lumitac 22-1, manufactured by Tosoh Corporation)
MFR: 2.0 g / 10 min) and a crosslinked polyolefin-based foam was obtained under the same conditions as in Example 1 except that the amount of dicumyl peroxide added was 0.7 parts by weight.

The obtained foam had a uniform surface and fine cells, a foaming ratio of 20 times, and a gel fraction of 75%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 10 Density of LLDPE produced by Ziegler catalyst =
LLDPE having a weight average molecular weight of 89,000 g / cm ³ (manufactured by Tosoh Corporation, trade name: Nipolon-LM50,
MFR: 3.0 g / 10 min), and a crosslinked polyolefin-based foam was obtained under the same conditions as in Example 1 except that the addition amount of dicumyl peroxide was changed to 0.7 part by weight.

The obtained foam had a uniform surface, fine cells, an expansion ratio of 20 and a gel fraction of 73%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 11 Density of LLDPE produced by Ziegler catalyst =
LLDPE having a weight-average molecular weight of 0.900 g / cm ³ and a weight-average molecular weight of 85,000 (trade name: Lumitac 22-1, manufactured by Tosoh Corporation)
MFR: 2.0 g / 10 min), a low molecular weight polyethylene wax having a viscosity average molecular weight of 6,400 and a melting point of 105 ° C. (Mitsui Chemicals, trade name:
Mitsui High Wax NL800, density: 0.920 g / c
m ³ ), and a crosslinked polyolefin-based foam was obtained under the same conditions as in Example 1 except that the amount of dicumyl peroxide added was changed to 0.7 part by weight.

The obtained foam had a uniform surface, fine cells, an expansion ratio of 20 times, and a gel fraction of 70%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 12 Density of LLDPE produced by Ziegler catalyst =
LLDPE having a weight-average molecular weight of 0.900 g / cm ³ and a weight-average molecular weight of 85,000 (trade name: Lumitac 22-1, manufactured by Tosoh Corporation)
MFR: 2.0 g / 10 min), low-molecular-weight polyethylene wax, low-molecular-weight polypropylene wax having a viscosity-average molecular weight of 7,000 and a melting point of 145 ° C (trade name: Mitsui High Wax NP055, manufactured by Mitsui Chemicals, density: 0.900 g)
/ Cm ³ ) and a crosslinked polyolefin-based foam was obtained under the same conditions as in Example 1 except that the amount of dicumyl peroxide added was 0.7 parts by weight.

The obtained foam had a uniform surface, fine cells, an expansion ratio of 20 times, and a gel fraction of 70%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Example 13 Density of LLDPE produced by Ziegler catalyst =
LLDPE having a weight-average molecular weight of 0.900 g / cm ³ and a weight-average molecular weight of 85,000 (trade name: Lumitac 22-1, manufactured by Tosoh Corporation)
MFR: 2.0 g / 10 min), a low molecular weight polyethylene wax having a viscosity average molecular weight of 4,000 and a melting point of 118 ° C. (manufactured by Mitsui Chemicals, trade name:
Mitsui High Wax 410P, density: 0.950 g / cm
³ ) A crosslinked polyolefin-based foam was obtained under the same conditions as in Example 1 except that the amount of dicumyl peroxide added was changed to 0.7 part by weight.

The resulting foam had a uniform surface, fine cells, an expansion ratio of 20 and a gel fraction of 72%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 1 Density of LLDPE produced by high-pressure radical polymerization =
LDPE with 0.921 g / cm ³ and weight average molecular weight = 55000 (trade name, Petrocene 190, MF, manufactured by Tosoh Corporation)
R: 4.0 g / 10 min), and molding was carried out under the same conditions as in Example 1 except that the low molecular weight polyethylene wax was not added and the addition amount of dicumyl peroxide was 0.2 parts by weight. Outgassing occurred and no foam was obtained. The gel fraction of this sample was 9%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 2 Density of LLDPE produced by high-pressure radical polymerization =
LDPE with 0.921 g / cm ³ and weight average molecular weight = 55000 (trade name, Petrocene 190, MF, manufactured by Tosoh Corporation)
R: 4.0 g / 10 min), and a crosslinked polyolefin-based foam was obtained under the same conditions as in Example 1 except that no low-molecular-weight polyethylene wax was added.

The obtained foam had a uniform surface, fine cells, an expansion ratio of 25 times, and a gel fraction of 30%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 3 Density of LLDPE produced by high-pressure radical polymerization =
LDPE with 0.921 g / cm ³ and weight average molecular weight = 55000 (trade name, Petrocene 190, MF, manufactured by Tosoh Corporation)
R: 4.0 g / 10 min), and the same conditions as in Example 1 were used except that low-molecular-weight polyethylene wax was not added and the amount of dicumyl peroxide added was 0.7 parts by weight. I got

The obtained foam had a uniform surface, fine cells, an expansion ratio of 25, and a gel fraction of 46%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 4 Density of LLDPE produced by high-pressure radical polymerization =
LDPE with 0.921 g / cm ³ and weight average molecular weight = 55000 (trade name, Petrocene 190, MF, manufactured by Tosoh Corporation)
R: 4.0 g / 10 min), and the same conditions as in Example 1 were used except that the low molecular weight polyethylene wax was not added and the amount of dicumyl peroxide added was 0.9 parts by weight. I got

However, the foam had cracks all over its surface, and a good foam could not be obtained. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 5 Density of LLDPE produced by high-pressure radical polymerization =
LDPE with 0.921 g / cm ³ and weight average molecular weight = 55000 (trade name, Petrocene 190, MF, manufactured by Tosoh Corporation)
R: 4.0 g / 10 min), and the same conditions as in Example 1 were used except that the low-molecular-weight polyethylene wax was not added and the amount of dicumyl peroxide added was 1.1 parts by weight. I got

The obtained foam has cracks on the surface,
A uniform foam was not obtained. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 6 A crosslinked polyolefin foam was obtained under the same conditions as in Example 1 except that the low molecular weight polyethylene wax was not added and that the amount of dicumyl peroxide was changed to 0.5 part by weight.

The obtained foam had a uniform surface, fine cells, an expansion ratio of 9 and a gel fraction of 97%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 7 A crosslinked polyolefin foam was obtained under the same conditions as in Example 1 except that the low molecular weight polyethylene wax was not added and the amount of dicumyl peroxide was changed to 0.7 part by weight.

The obtained foam had a uniform surface, fine cells, an expansion ratio of 6 and a gel fraction of 98%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 8 A crosslinked polyolefin foam was obtained under the same conditions as in Example 1 except that the low molecular weight polyethylene wax was not added and the amount of dicumyl peroxide was changed to 0.9 part by weight.

The foam obtained had a uniform surface, fine cells, an expansion ratio of 6 and a gel fraction of 98.5%.
Had. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 9 A crosslinked polyolefin foam was obtained under the same conditions as in Example 1 except that the low-molecular-weight polyethylene wax was not added and that the amount of dicumyl peroxide was changed to 0.4 part by weight.

[0098] Outgassing occurred in the obtained foam, and uniform foaming was not possible. However, it had a gel fraction of 78%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

Comparative Example 10 Density of LLDPE produced by high-pressure radical polymerization =
0.920 g / cm ³ , weight average molecular weight = 200000
LDPE (manufactured by Tosoh, trade name Petrocene 170, M
FR: 0.3 g / 10 min), and a low molecular weight polyethylene wax was not added, and the addition amount of dicumyl peroxide was 0.5 parts by weight. I got

The obtained foam has a uniform surface,
The cell was non-uniform, had an expansion ratio of 20 times, and had a gel fraction of 60%. Table 1 shows the blending of the raw materials and the physical properties of the resin, and Table 2 shows the physical properties of the foam obtained.

[0101]

[Table 1]

[Table 2]

EFFECT OF THE INVENTION By using the polyolefin resin composition of the present invention, a foam having uniformity of cells, toughness and high foamability in various cross-linking molding methods while maintaining the excellent properties of the polyolefin resin. Can be obtained, and furthermore, molding workability, which has been difficult with the prior art, can be achieved, which can contribute to improvement in productivity.

Claims (16)

[Claims] 1. A cross-linked polyolefin foam obtained by subjecting a polyolefin resin composition for foam molding containing a polyolefin resin composition and a foaming agent to cross-foam molding, and having the following properties (a) to (c): A foam having: (A) Immediately after P-xylene extraction at 120 ° C. for 24 hours, the gel fraction represented by the residual amount after drying at 80 ° C. and 10 mmHg for 24 hours is 10 to 90%. (B) Formula (1) Swelling degree is 30 or less (C) When the glass transition point obtained from the temperature dependence of dynamic viscoelasticity is expressed as a tan δ peak obtained when dynamic viscoelasticity is measured at a frequency of 10 Hz, the peak is observed. If it is not observed or observed, it has one glass transition point, and the ratio α (α = α) between the storage modulus at 0 ° C. (E ′ ₀ ) and the storage modulus at 100 ° C. (E ′ ₁₀₀ )
logE _'0 / logE' ₁₀₀₎ 10 to 30 2. The foam according to claim 1, wherein the polyolefin resin composition comprises 5 to 50 parts by weight of a low molecular weight polyolefin wax based on 100 parts by weight of the polyolefin resin. 3. A polyolefin resin composition having a density of 0.1.
In the range of 860 to 0.970 g / cm ³ , the viscosity average molecular weight determined by the viscosity method was 15 per 100 parts by weight of the polyolefin resin having a weight average molecular weight determined by gel permeation chromatography of 60,000 or more.
In the range of 00 to 10,000, the melting point by DSC measurement is 1
The foam according to claim 1, comprising 5 to 50 parts by weight of a low molecular weight polyolefin wax in the range of 00 to 160 ° C. 4. The polyolefin resin is a linear ethylene homopolymer or a linear ethylene / α-olefin copolymer comprising ethylene and an α-olefin having 3 to 12 carbon atoms. Item 4. The foam according to item 2 or 3. 5. The polyolefin resin according to claim 1, wherein
The foam according to claim 4, which satisfies the requirement (c). (A) The MFR at 190 ° C. and a load of 2160 g is 0.
1 to 30 g / 10 minutes (b) The size of the die is L / D = 8 / 2.095 (m
m), and the melt tension when stretched at a draw ratio of 50 using a capillary rheometer with a cylinder temperature of 160 ° C. is 50 to 300 mN. 6. The foam according to claim 2, wherein the low molecular weight polyolefin wax is a low molecular weight polyethylene wax. 7. A polyolefin resin composition for foam molding,
The foaming agent is contained in an amount of 2 to 30 parts by weight based on 100 parts by weight of the polyolefin resin composition.
7. The foam according to items 6. 8. A material having a density of 0.860 to 0.970 g / cm ^3.
In the range, the weight average molecular weight determined by gel permeation chromatography is 100 parts by weight of a polyolefin resin having a molecular weight of 60,000 or more.
A polyolefin-based resin composition comprising 5 to 50 parts by weight of a low-molecular-weight polyolefin wax having a melting point in the range of 100 to 160 ° C by SC measurement. 9. The polyolefin resin is a linear ethylene homopolymer or a linear ethylene / α-olefin copolymer comprising ethylene and an α-olefin having 3 to 12 carbon atoms. Item 10. The polyolefin resin composition according to Item 8. 10. The polyolefin resin according to any one of the following (a) to (a).
The polyolefin-based resin composition according to claim 9, which satisfies the requirement (c). (A) The MFR at 190 ° C. and a load of 2160 g is 0.
1 to 30 g / 10 minutes (b) The size of the die is L / D = 8 / 2.095 (m
m), and the melt tension when stretched at a draw ratio of 50 using a capillary rheometer with a cylinder temperature of 160 ° C. is 50 to 300 mN. 11. The polyolefin resin composition according to claim 8, wherein the low molecular weight polyolefin wax is a low molecular weight polyethylene wax. 12. A polyolefin resin composition for foam molding, comprising the polyolefin resin composition according to claim 8. 13. A polyolefin resin composition for foam molding, comprising 2 to 30 parts by weight of a foaming agent with respect to 100 parts by weight of the polyolefin resin composition according to claim 8. 14. A polyolefin resin composition for foam molding comprising 2 to 30 parts by weight of a blowing agent and 100 parts by weight of a polyolefin resin composition according to claim 8 to 11. 15. A foam obtained by crosslinking and foaming the polyolefin resin composition for foam molding according to claim 12. 16. The foam according to claim 1, which has an expansion ratio of 2 times or more.