Polyolefin resin foam and molded article obtained by molding the same

Abstract

To provide a polyolefin resin foam that has a homogeneously foamed cell structure at a high expansion ratio, and also causes little contamination.SOLUTION: A polyolefin resin foam contains a block copolymer having a specific structure, which can be obtained by the reaction between (a) a polyolefin having one end modified with acid and (b) a polyether or a modified product thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyolefin resin foam and a molded article obtained by molding the same. [Background technology]

[0002] Foams made from polyolefin resins not only have the inherent chemical resistance of resins, but are also lightweight and have good thermal insulation properties, cushioning against external stress, and impact resistance. Furthermore, they can be easily molded by hot secondary molding such as vacuum forming. Therefore, they are widely used in a variety of applications, including cushioning materials, thermal insulation materials, food containers, and automotive components.

[0003] In order to obtain a foam that is lighter in weight and has an excellent balance between impact resistance and rigidity, various polyolefin resin foams have been proposed that aim for a high expansion ratio and a homogeneous foam cell structure. For example, a foam (Patent Document 1) has been proposed, which is produced by foaming a composition consisting of a foamable polyolefin resin whose main component is polypropylene and whose first normal stress difference at a predetermined shear stress value is equal to or greater than a predetermined value, and a chemical foaming agent such as azodicarbonamide. Also proposed are foams obtained by foaming a composition consisting of a foamable polyolefin resin, the main component of which is a polypropylene resin, the melt flow rate and first normal stress difference of which are within a predetermined range at a predetermined shear stress value in the molten state, and a chemical foaming agent such as azodicarbonamide (Patent Document 2), and foams obtained by foaming a composition consisting of a foamable polyolefin resin, the main component of which is a polypropylene resin modified with an unsaturated carboxylic acid or its acid anhydride, and a chemical foaming agent (Patent Document 3). These proposals disclose foamable polyolefin resins obtained by reacting acid-modified polypropylene with a polyamine compound as the polypropylene resin. In addition, a foam injection molded article has been proposed in which a polyolefin molding material containing a resin component consisting of a polyolefin resin and a thermoplastic elastomer that is not completely compatible with the polyolefin resin is penetrated with a supercritical gas, and the material is injected into a mold while maintaining the supercritical state, and then degassed and foamed (Patent Document 4). Furthermore, polyolefin foams using resin acids such as abietic acid as organic foaming aids have been proposed (Patent Document 5). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-240976 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-8770 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-2228 [Patent Document 4] Japanese Patent Application Laid-Open No. 2003-206369 [Patent Document 5] Japanese Patent Application Publication No. 5-247252 Summary of the Invention [Problem to be solved by the invention]

[0005] Even in the conventional polyolefin resin foams proposed so far, the foaming uniformity is not sufficient, and further improvements are required. Furthermore, when a chemical foaming agent such as azodicarbonamide or an organic foaming aid such as abietic acid is used, there is a problem that these foaming agents bleed out after molding, generating corrosive gases and contaminating the molded body.

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a polyolefin resin foam which has a high expansion ratio, a homogeneous foam cell structure, and is low in contamination. [Means for solving the problem]

[0007] The present invention covers the following [1] to [8]. [1] A polyolefin resin foam containing a block copolymer (A) represented by the following general formula (1) or (2): [ka] (In the formula, R 1 is a polyolefin residue, A 1 is a divalent group having a polyoxyalkylene group, X 1 is -O- or -N(R 2 )-(R 2 represents a hydrogen atom or an alkyl group, alkenyl group or acyl group having 1 to 22 carbon atoms), B 1 represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group, an aryl group, an alkylaryl group, an acyl group, or a structure represented by the following formula (3) or (4), and M 1 represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an organic ammonium. [ka] (In the formula, R 3 is a polyolefin residue, A 2 represents a divalent group having a polyoxyalkylene group, B 2 represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group, an aryl group, an alkylaryl group, an acyl group, or a structure represented by the following formula (3) or (4): [ka] (In the formula, R 4 is a polyolefin residue, X 2 is -O- or -N(R 5 )-(R 5 represents a hydrogen atom or an alkyl group, alkenyl group or acyl group having 1 to 22 carbon atoms), M 2 represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an organic ammonium. [ka] (In the formula, R 6 represents a polyolefin residue. [2] R in the general formula (1) 1is a polyisobutylene residue. [3] R in the general formula (1) 1 and R in the general formula (3) 4 is a polyisobutylene residue. [4] R in the general formula (2) 3 and R in the general formula (4) 6 is a polyisobutylene residue. [5] A in the general formula (1) 1 and A in general formula (2) 2 However, -(R 8 O) m -R 7 -(OR 9 ) n -(In the formula, R 7 is a divalent organic group having 1 to 30 carbon atoms, R 8 , R 9 are each independently an alkylene group having 2 to 4 carbon atoms, and m and n are each independently an integer of 1 to 100. [6] A in the general formula (1) 1 is a polyoxyalkylene group, and X 1 -N(R 2 )-(wherein, R 2 represents an acyl group having 1 to 22 carbon atoms.) The polyolefin resin foam according to [1]. [7] The polyolefin resin foam according to [1], which contains 0.1 to 20 parts by mass of the block copolymer (A) per 100 parts by mass of the polyolefin resin. [8] A molded article obtained by molding the polyolefin resin foam according to any one of [1] to [7]. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a polyolefin resin foam that has a uniform cell structure, in particular, fine cells with a small average cell diameter, a high closed cell rate and cell number density, and a narrow cell diameter distribution, and thus has a uniform foamed surface and a fine cell diameter distribution, and is low in contamination. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a view showing an SEM photograph of the resin foam of Example 4. [Figure 2] FIG. 2 is a view showing an SEM photograph of the resin foam of Example 10. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention relates to a block copolymer (A) represented by the general formula (1) or the general formula (2). The present invention also relates to a molded article obtained by molding the polyolefin resin foam.

[0011] The block copolymer (A) according to the present invention can be obtained by reacting (a) a polyolefin having one end acid-modified with (b) a polyether or a modified product thereof.

[0012] R, which is a polyolefin residue in the general formulas (1) and (2), 1 , R 3 , R 4 , R 6 is a portion derived from the polyolefin of the (a) polyolefin having one end acid-modified. The polyolefin may be a polyolefin (polymerization method) obtained by polymerizing one or a mixture of two or more olefins having 2 to 30 carbon atoms, preferably 2 to 12 carbon atoms, and more preferably 2 to 10 carbon atoms, or a low molecular weight polyolefin (thermal degradation method) obtained by thermal degradation of a high molecular weight polyolefin. Such polyolefins are those whose main component (50% or more, preferably 65% ​​or more) is a polyolefin that can be modified at least at one end, and in terms of ease of modification, those with an average number of terminal double bonds per molecule of, for example, 0.5 to 1.5 can be preferably used. The number average molecular weight Mn of the polyolefin is preferably 800 to 20,000, more preferably 1,000 to 10,000, and most preferably 1,500 to 9,000.

[0013] Examples of the olefins having 2 to 30 carbon atoms include ethylene, propylene, 1-butene, 2-butene, and isobutene; α-olefins having 5 to 30 carbon atoms, preferably 5 to 12 carbon atoms, and more preferably 5 to 10 carbon atoms, such as 4-methyl-1-pentene, 1-pentene, 1-octene, 1-decene, and 1-dodecene; and dienes having 4 to 30 carbon atoms, preferably 4 to 18 carbon atoms, and more preferably 4 to 8 carbon atoms, such as butadiene, isoprene, cyclopentadiene, and 11-dodecadiene. Among these, isobutene and propylene are preferred as the olefin, and for example, poly(iso)butene, which is a homopolymer of isobutene or a copolymer of isobutene and n-butene, or polypropylene is preferred as the polyolefin. Among them, R in general formula (1) which is a polyolefin residue 1 For example, R in general formula (1) is preferably a polyisobutylene residue. 1 and R in general formula (3) 4 is a polyisobutylene residue, and R 3 and R in general formula (4) 6 is a polyisobutylene residue.

[0014] As the (a) polyolefin having one end acid-modified, a polyolefin having an average number of terminal double bonds per molecule of 0.5 to 1.5, preferably 0.7 to 1.0, preferably poly(iso)butene or polypropylene, modified with a dicarboxylic acid such as maleic acid (anhydride) or fumaric acid can be preferably used.

[0015] The degree of acid modification per molecule of polyolefin having one terminal acid modified can be determined from the number average molecular weight Mn by GPC and the acid value or saponification value. To synthesize a block copolymer having a structure represented by general formula (1) or general formula (2) in which (a) a block derived from polyolefin having one terminal acid modified and (b) a block derived from polyether or its modified product are bonded, the degree of acid modification is preferably 0.5 to 1.5, more preferably 0.7 to 1.0.

[0016] In the general formulas (1) and (2), A 1 , A 2 are divalent groups each having a polyoxyalkylene group, and the polyoxyalkylene unit is preferably contained in the composition in an amount of 20 to 100 mass%, more preferably 50 to 100 mass%, and particularly preferably 70 to 100 mass%. It contains These A 1 , A 2 Specifically, the —(R 8 O) m -R 7 -(OR 9 ) n -(R 7 is a divalent organic group having 1 to 30 carbon atoms, R 8 , R 9 are each independently an alkylene group having 2 to 4 carbon atoms, and m and n are each independently an integer of 1 to 100). Also A 1 (b) Polyethers constituting the polyethers are 12 O)pR 11 -NHCO-R 10- (wherein R 10 represents a linear or branched alkylene or alkenylene group having 1 to 21 carbon atoms; R 11 R represents a linear or branched alkylene group having 1 to 4 carbon atoms. 12 represents an alkylene group having 2 to 4 carbon atoms, and p represents an integer of 1 to 100. * represents X 1 ) is also included.

[0017] A is a divalent group having a polyoxyalkylene group in the general formulas (1) and (2). 1 , A 2 is a moiety derived from the (b) polyether or a modified product thereof. Examples of the (b) polyether include (b1) polyether diol, (b2) polyether diamine in which the hydroxy group is converted to an amino group, (b3) polyether monool, and (b4) alkylene oxide adduct of amide alcohol.

[0018] The above (b1) polyether diol is obtained by adding an alkylene oxide to a diol compound, and in addition to polyethylene glycol and polypropylene glycol, for example, a diol having the general formula: HO-(R 8 O) m -R 7 -(OR 9 ) n In the formula, R 7 is the residue obtained by removing the hydroxy group from a diol compound, R 8 , R 9 represents an alkylene group having 2 to 4 carbon atoms, and m and n represent the number of alkylene oxides added per hydroxy group of the diol. 8 O) and n (OR 9) may be the same or different oxyalkylene groups, and when they are composed of two or more types of oxyalkylene groups, the bonding form may be block or random, or a combination of these. m and n are usually integers of 1 to 100, preferably 2 to 30, and particularly preferably 3 to 10. m and n may be the same or different.

[0019] The diol compounds include dihydric alcohols (for example, aliphatic, alicyclic or aromatic dihydric alcohols having 2 to 12 carbon atoms), dihydric phenols having 6 to 18 carbon atoms, and tertiary amino group-containing diols. Examples of aliphatic dihydric alcohols include alkylene glycols (ethylene glycol, propylene glycol), 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and 1,12-dodecanediol. Examples of alicyclic dihydric alcohols include cyclohexanedimethanol and hydrogenated bisphenols. Examples of aromatic dihydric alcohols include xylylenediol. Examples of dihydric phenols include monocyclic dihydric phenols (hydroquinone, catechol, resorcinol, urushiol, etc.), bisphenols (bisphenol A, bisphenol F, bisphenol S, 4,4'-dihydroxydiphenyl-2,2-butane, dihydroxybiphenyl, etc.), and condensed polycyclic dihydric phenols (dihydroxynaphthalene, binaphthol, etc.). Examples of tertiary amino group-containing diols include bishydroxyalkylated products of aliphatic or alicyclic primary monoamines having 1 to 30 carbon atoms (such as methylamine, ethylamine, cyclopropylamine, 1-propylamine, 2-propylamine, amylamine, isoamylamine, hexylamine, 1,3-dimethylbutylamine, 3,3-dimethylbutylamine, 2-aminoheptane, 3-aminoheptane, cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, nonylamine, decylamine, undecylamine, and dodecylamine), and bishydroxyalkylated products of aromatic primary monoamines having 6 to 12 carbon atoms (such as aniline and benzylamine). Among these diol compounds, aliphatic dihydric alcohols and bisphenols are preferred. Among these, ethylene glycol and bisphenol A are particularly preferred.

[0020] The alkylene oxide to be added to the diol compound includes alkylene oxides having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, and butylene oxide, and one or more of these can be used. The addition of the alkylene oxide is carried out, for example, in the presence of an alkali catalyst at a temperature of 100 to 200°C.

[0021] Among these, examples of polyether diols that are preferably used as (b1) include polyethylene glycols or ethylene oxide adducts of bisphenol A having a molecular weight of 100 to 2,000, more preferably 200 to 1,000.

[0022] The (b2) polyetherdiamine can be obtained by converting the hydroxy groups of the polyetherdiol into amino groups by a known method, and can be, for example, a polyetherdiamine represented by the general formula: HN-(R 8 O) m -R 7 -(OR 9 ) n In the formula, R 7 , R 8, R 9 , m and n are the same as those listed above for the polyether diol.

[0023] The (b3) polyether monool can be obtained by adding an alkylene oxide to a monool such as a monohydric alcohol or a phenol, and can be represented by, for example, the general formula: RO-(AO) k Examples of suitable compounds include compounds represented by the formula -H. In this formula, R represents a residue obtained by removing a hydroxy group from any monool, A represents an alkylene group having 2 to 4 carbon atoms, and k represents the number of alkylene oxides added. The k (AO)s may be the same or different oxyalkylene groups, and when they are composed of two or more types of oxyalkylene groups, the bonding form may be block or random, or a combination of these. k is an integer of usually 1 to 200, preferably 3 to 60, and particularly preferably 5 to 30.

[0024] Examples of monohydric alcohols include linear or branched aliphatic saturated alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, isobutyl alcohol, tertiary butyl alcohol, isoamyl alcohol, octyl alcohol, 2-ethylhexyl alcohol, lauryl alcohol, tridecyl alcohol, cetyl alcohol, stearyl alcohol, isostearyl alcohol, and synthetic alcohols (e.g., Ziegler alcohol, oxoalcohols); aliphatic unsaturated alcohols such as allyl alcohol, crotyl alcohol, propargyl alcohol, oleyl alcohol, and linoleyl alcohol; aliphatic saturated and unsaturated alcohols such as mint alcohol, tallow-reduced alcohol, and coconut oil-reduced alcohol; alicyclic alcohols such as cyclopentanol and cyclohexanol; and aromatic alcohols such as benzyl alcohol and cinnamyl alcohol. Phenols include, in addition to phenol, cresol, isopropyl phenol, tertiary butyl phenol, and tertiary amyl phenol. Among these, monohydric alcohols are preferred, and aliphatic monohydric alcohols are more preferred.

[0025] The (b4) alkylene oxide adduct of amide alcohol (polyether monool containing an amide bond) can be, for example, a compound represented by the general formula: HR 10 -CONH-R 11 -O-(R 12 O) pH and can be obtained by adding alkylene oxide to amide alcohol by known methods. In the above formula, R 10 represents a linear or branched alkylene or alkenylene group having 1 to 21 carbon atoms; R 11 R represents a linear or branched alkylene group having 1 to 4 carbon atoms. 12 represents an alkylene group having 2 to 4 carbon atoms, and p represents an integer of 1 to 100.

[0026] Above R 10 Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group, a dodecyl group such as a lauryl group, a tetradecyl group such as a myristyl group, a hexadecyl group such as a palmityl group, an octadecyl group such as a stearyl group, an oleyl group, an eicosyl group, and a behenyl group. R 11 Specific examples include a methylene group, an ethylene group, a propylene group, and a butylene group. (R 12 Specific examples of O) include an ethyleneoxy group, a propyleneoxy group, and a butyleneoxy group.

[0027] Amido alcohols can be produced, for example, by amidation reaction of alkanolamines with carboxylic acids or reactive derivatives thereof (for example, ester compounds thereof). Examples of alkanolamines include monoethanolamine, n-propanolamine, and isopropanolamine. Furthermore, examples of carboxylic acids or reactive derivatives thereof include carboxylic acids or alkyl esters thereof, such as formic acid, acetic acid, propionic acid, methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate, and methyl behenate.

[0028] The alkylene oxide to be added to the amido alcohol may be an alkylene oxide having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, or butylene oxide, and one or more of these may be used. The addition of the alkylene oxide may be carried out, for example, in the presence of an alkali catalyst at a temperature of 80 to 200°C. In the general formula, p is usually an integer of 1 to 100, preferably 4 to 60, and particularly preferably 6 to 40. When p is 2 or more, (R 12 O) When p is composed of two or more types of alkyleneoxy groups, the bonding form may be block or random, or a combination thereof.

[0029] Examples of the (b) modified polyether (b5) include the (b1) polyether diol or (b2) polyether diamine modified aminocarboxylic acid products, and (b2) polyether diamine modified monocarboxylic acid products. The aminocarboxylic acid modified products can be obtained by reacting the (b1) or (b2) with an aminocarboxylic acid or a lactam. The monocarboxylic acid modified products can be obtained by reacting the (b2) polyether diamine or the like with a monocarboxylic acid having 1 to 22 carbon atoms.

[0030] [Block copolymer] The reaction between (a) a polyolefin having one end acid-modified and (b) a polyether or a modified product thereof can be carried out, if necessary, in the presence of a catalyst at 150 to 250° C. Specific examples of the catalyst include acid catalysts such as sulfuric acid, paratoluenesulfonic acid, and phosphoric acid; alkali catalysts such as alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide; and metal oxides such as calcium oxide, magnesium oxide, zinc oxide, lead oxide, and tin oxide. The catalyst may also be an antimony-based catalyst such as antimony trioxide, a tin-based catalyst such as monobutyltin oxide, a titanium-based catalyst such as tetrabutyl titanate, a zirconium-based catalyst such as tetrabutyl zirconate, an organic acid metal salt-based catalyst such as zirconyl acetate or zinc acetate, a palladium-based catalyst such as palladium acetate or tetrakis(triphenylphosphine)palladium, or a combination of two or more of these. Among these, zirconium-based catalysts and organic acid metal salt-based catalysts are preferred, and zirconium acetate is particularly preferred. It is ruconil.

[0031] The charging ratio of (a) polyolefin having one end acid-modified and (b) polyether is not particularly limited, but in terms of obtaining the block copolymer of the present invention in high yield, a molar ratio of (a) / (b) of 0.8 / 1 to 3 / 1 is preferred.

[0032] When an acid group (carboxyl group) is present in the block copolymer of (a) a polyolefin having one end acid-modified and (b) a polyether, it may be neutralized with a basic substance. Examples of alkaline substances used for neutralization include hydroxides, carbonates, phosphates, acetates, silicates, etc. of alkali metals such as lithium, potassium, sodium, etc.; hydroxides, carbonates, etc. of alkaline earth metals such as calcium, magnesium, etc.; ammonia; organic amines; and combinations of two or more of these.

[0033] The block copolymer (A) according to the present invention has a structure represented by the general formula (1) or (2). For example, in the general formula (1), A 1 is a polyoxyalkylene group, and X 1 -N(R 2 )-(wherein, R 2 represents an acyl group having 1 to 22 carbon atoms. 1 is a hydrogen atom.

[0034] [Polyolefin resin foam] The resin foam can be obtained through a step of impregnating a foam-forming resin material with a blowing agent (compatibilizing step) and a step of degassing the foam-forming resin material impregnated with the blowing agent. The polyolefin resin foam according to the present invention can be obtained, for example, by impregnating a polyolefin resin composition containing a polyolefin resin and the block copolymer (A) with a physical foaming agent, such as an inert gas, at high temperature and high pressure, and then releasing the pressure.

[0035] <Polyolefin-based resin composition> In the present invention, the polyolefin resin constituting the foam is not particularly limited, and any known polyolefin resin can be selected. In order to easily obtain the desired physical properties, polyethylene resins, polypropylene resins, and combinations thereof are preferred.

[0036] Examples of polyethylene resins include branched low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, and polymers containing ethylene monomer as the main component, such as ethylene-propylene copolymers and ethylene-α-olefin copolymers. In the above examples, low density refers to a density of 0.91 to 0.94 g / cm. 3 It is preferable that the density is 0.91 to 0.93 g / cm 3 It is more preferable that the high density is 0.95 to 0.97 g / cm.3 It is preferable that the density is 0.95 to 0.96 g / cm 3 The medium density is a density intermediate between the low density and the high density.

[0037] The polypropylene-based resin is preferably a propylene homopolymer or a copolymer of propylene and another olefin, and more preferably a propylene homopolymer. Examples of other olefins copolymerized with propylene include, in addition to ethylene, α-olefins having 4 to 10 carbon atoms, such as 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, and 1-decene. The copolymer of propylene and another olefin is preferably a copolymer with a small amount of ethylene component, and may be either a random copolymer or a block copolymer, but is preferably a block copolymer due to its excellent heat resistance. Furthermore, as the polypropylene-based resin, from the viewpoint of excellent foaming properties, high melt tension polypropylene is used. A propylene-based resin can be used. High melt tension polypropylene-based resins include those that have free-end long-chain branches in their molecular structure or contain high molecular weight components to increase melt tension. Commercially available high melt tension polypropylenes can be used.

[0038] The polyolefin resins may be used alone or in a suitable combination of two or more kinds.

[0039] The polyolefin resin composition of the present invention may contain other polymer components in addition to the polyolefin resins (polyethylene resins and polypropylene resins) as long as the physical properties and moldability of the foam are not impaired. As the other polymer components in addition to the polyolefin resin components, resins highly compatible with the polyolefin resins, such as ethylene-ethyl acrylate copolymer resins, ethylene-vinyl acetate copolymer resins, polybutene resins, and poly-4-methylpentene-1 resins, may also be contained. Of all the polymer components (100% by mass) in the polyolefin resin composition, the other polymer components can account for 0 to 50% by mass.

[0040] Various additives may be added to the polyolefin resin composition as long as they do not impair the effects of the present invention, such as foam nucleating agents, colorants, nucleating agents, antioxidants, heat stabilizers, weather resistance agents, ultraviolet absorbers, flame retardants, inorganic fillers, antibacterial agents, and shrinkage inhibitors.

[0041] An example of a method for producing a polyolefin resin foam will be described in detail below. First, a resin composition comprising the polyolefin resin, the block copolymer (A), and optionally other components is fed into an extruder, which may be a single-screw extruder, a twin-screw extruder, or a tandem extruder combining the two.

[0042] Next, a physical foaming agent such as an inert gas or an aliphatic hydrocarbon is injected into the molten resin composition midway through the extruder and mixed uniformly. The inert gas or aliphatic hydrocarbon may be any gas that impregnates the resin composition. Examples of gases that are gaseous at room temperature and pressure include nitrogen, helium, carbon dioxide, butane, and mixtures thereof. Inert gases such as carbon dioxide and nitrogen are preferred, with carbon dioxide being particularly preferred, due to their ease of handling, high safety, and excellent working environment. Furthermore, bringing the inert gas into a supercritical state can be advantageous in terms of the amount of dissolution (impregnation) in the resin, the expansion ratio, and the formation of fine bubbles.

[0043] The amount of physical foaming agent (e.g., inert gas) can be adjusted appropriately depending on the expansion ratio of the resin foam. However, if the amount of physical foaming agent (e.g., inert gas) is too small, the expansion ratio of the resin foam will be low, which may result in reduced lightness and reduced thermal insulation. On the other hand, if the amount of physical foaming agent (e.g., inert gas) is too large, the bubbles will be more likely to break as they grow, which may reduce the closed cell ratio in the resin foam or cause the expansion ratio to become too high, resulting in insufficient strength of the foam. Considering the occurrence of such problems, the physical foaming agent (such as an inert gas) can generally be impregnated in an amount of 0.1 to 10 parts by mass, preferably 1 to 5 parts by mass, per 100 parts by mass of the resin composition.

[0044] A resin composition mixed with a physical foaming agent (e.g., an inert gas in a supercritical state) in an extruder is extruded and foamed through a mold attached to the tip of the extruder to obtain a polyolefin resin foam having a desired shape. For example, a circular die is used as the mold to obtain a sheet-like resin foam, which is suitable for thermal secondary molding.

[0045] The resin foam of the present invention preferably has an average cell diameter of 10 to 100 μm, more preferably 20 to 90 μm, or even 20 to 80 μm, from the viewpoints of the heat insulating properties and appearance of the foam.

[0046] The resin foam of the present invention is less likely to experience a decrease in expansion ratio, and from the viewpoint of the heat insulating properties of the foam, it is preferable that the closed cell ratio of the foam is 70% or more, for example 80% or more, more preferably 90% or more.

[0047] [Molded body] The resin foam of the present invention can be readily molded into secondary shapes using a variety of molding methods, including vacuum molding, pressure molding (extrusion pressure molding, hot plate pressure molding, vacuum pressure molding, etc.), free blow molding, bending, matched mold molding, hot plate molding, and other conventional thermoforming processes. Molded articles with three-dimensional shapes, such as concave shapes, can be obtained, for example, by pressure molding, in which a heated resin foam sheet is pressed against a mold using compressed air, vacuum molding, in which a heated sheet is drawn into the mold by creating a vacuum between the mold and the heated resin foam sheet, or vacuum pressure molding.

[0048] The resin foam of the present invention can also be combined with various materials having different rigidity or elasticity, such as other resin films, resin sheets, rubber sheets, etc. The composite of the foam and the various materials may be produced by laminating them together using an adhesive, by thermal lamination, or by heat fusion bonding by co-extrusion.

[0049] The molded article (foamed molded article) obtained by thermally secondary molding the resin foam of the present invention is one in which the deterioration of physical properties due to thermoforming is suppressed, and the molded article is lightweight, has excellent insulation and cushioning properties, and has a beautiful appearance, making it suitable for use as a food container, etc.

[0050] Although the details of the mechanism by which the block copolymer (A) of the present invention improves the foaming behavior of polyolefin resins are unknown, one possible reason is that the interfacial tension between the copolymer and the physical foaming agent (foaming gas) is lower than the interfacial tension between the copolymer and the polyolefin, thereby reducing the energy required to generate bubbles, which in turn increases the bubble nucleation rate and results in the formation of many fine bubbles. For example, with regard to carbon dioxide (physical foaming agent) used in the examples, infrared spectroscopy confirmed that the absorption peak attributable to carbon dioxide in the measurement sample containing the copolymer was extremely large, which indicates that the copolymer has a high affinity for the physical foaming agent, carbon dioxide. The high affinity between the copolymer and the physical foaming agent may increase the amount of physical foaming agent impregnated into the resin to be foamed, which in turn may affect the uniformity of bubble diameter. [Example]

[0051] The present invention will be described below with reference to examples. However, the present invention is not limited in any way by the following production examples, examples, and comparative examples. In the examples, "parts" and "%" are by mass unless otherwise specified.

[0052] [Production Example 1: Synthesis of Amide Alcohol (Compound 1)] A glass flask equipped with a nitrogen inlet tube, stirrer, and thermometer was charged with 3205 g of methyl palmitate dissolved at 80°C. A previously prepared mixture of 731 g of monoethanolamine and 64 g of 28% sodium methylate was added dropwise over 5 hours. The mixture was then maintained at 80°C under a nitrogen atmosphere for 5 hours. The unreacted monoethanolamine and the reaction by-product methanol were removed by solvent removal, yielding 3560 g of a viscous liquid. The amine value of the resulting viscous liquid, minus the sodium methylate content, was 0.01 mg KOH / g. The IR spectrum showed an OH stretching band of 3300 cm. -1 , NH telescopic 3100cm -1 , C=O telescopic 1650cm -1 , NH angle angle 1565cm -1 The resulting product was designated Compound 1.

[0053] [Production Example 2: Synthesis of Amido Alcohol Ethylene Oxide Adduct (1)] 1500 g of the amide alcohol (Compound 1) obtained in Production Example 1 was charged in a molten state at 80°C into a stainless steel autoclave (hereinafter the same) equipped with a nitrogen inlet tube, a stirrer, and a thermometer, and the atmosphere was thoroughly purged with nitrogen. After heating to 90°C, 2750 g of ethylene oxide was introduced over 5 hours, and the mixture was aged at the same temperature for 2 hours to complete the reaction. An appropriate amount of Kyoward (registered trademark) 700SL (Kyowa Chemical Industry Co., Ltd.), an alkaline adsorbent, was then added for adsorption and filtration to obtain a pale yellow liquid. The resulting product (pale yellow liquid) had a hydroxyl value of 65.7 mg KOH / g and a moisture content of 0.02%.

[0054] [Production Example 3: Synthesis of Amido Alcohol Ethylene Oxide Adduct (2) (Compound 2)] 3000 g of the amide alcohol (Compound 1) obtained in Production Example 1 was charged in a molten state at 80°C into a stainless steel autoclave and thoroughly purged with nitrogen. After heating to 90°C, 1700 g of ethylene oxide was introduced over 5 hours and the mixture was aged at the same temperature for 2 hours to complete the reaction. An appropriate amount of Kyoward (registered trademark) 700SL (Kyowa Chemical Industry Co., Ltd.) was then added for adsorption and filtration to obtain a pale yellow liquid. The resulting product (pale yellow liquid) had a hydroxyl value of 119.8 mg KOH / g and a moisture content of 0.02%. The resulting product was designated Compound 2.

[0055] [Production Example 4: Synthesis of Block Copolymer 1] A stainless steel autoclave was charged with 7115 g of poly(iso)butenyl succinic anhydride (saponification value 18 mg KOH / g), 853 g of the amide alcohol ethylene oxide adduct (1) obtained in Production Example 2, and 52 g of the amide alcohol ethylene oxide adduct (2) obtained in Production Example 3. After thorough nitrogen purge and heating to 80°C, 261 g of 48% KOH and 219 g of potassium acetate were added. Further thorough nitrogen purge was performed, and the mixture was heated to 220°C. The mixture was then maintained at 220°C under reduced pressure of 0.2 kPa or less with trace nitrogen bubbling for 5 hours to obtain a product. The resulting product was a viscous polymer. The ester value of the product was 6.1 mg KOH / g. IR spectrum revealed a C=O stretching band of 1735 cm. -1 , C(=O)O- antisymmetric stretching 1561cm -1 , and the C(=O)-NC(=O) stretching at 1709 and 1772 cm -1 The resulting product was designated block copolymer 1.

[0056] [Production Example 5: Synthesis of Block Copolymer 2] A stainless steel autoclave was charged with 10,450 g of poly(iso)butenyl succinic anhydride (saponification value 18 mg KOH / g) and 850 g of polyethylene glycol (Toho Polyethylene Glycol 600, manufactured by Toho Chemical Industry Co., Ltd., hydroxyl value 187). After thorough nitrogen purge, the mixture was heated to 90°C, and then 125 g of 48% KOH was added. Further nitrogen purge was performed, the mixture was heated to 205°C, and then maintained at 205°C under reduced pressure of 0.2 kPa or less with trace nitrogen bubbling for 5 hours to obtain a product. The resulting product was a viscous polymer. The ester value of the product was 5.1 mg KOH / g. Furthermore, IR spectroscopy revealed a C=O stretching band at 1735 cm. -1 , C(=O)O- antisymmetric stretching 1561cm -1 The resulting product was designated block copolymer 2.

[0057] [Production Example 6: Synthesis of Block Copolymer 3] A stainless steel autoclave was charged with 3540 g of poly(iso)butenyl succinic anhydride (saponification value 36 mg KOH / g), 307 g of the amide alcohol ethylene oxide adduct (1) obtained in Production Example 2, and 48 g of the amide alcohol ethylene oxide adduct (2) obtained in Production Example 3. After thorough nitrogen replacement and heating to 80°C, 241 g of 48% KOH and 81 g of potassium acetate were added, followed by further thorough nitrogen replacement and heating to 160°C. The mixture was then maintained at 160°C, 0.2 kPa or less, and a small amount of nitrogen was bubbled under reduced pressure for 5 hours to obtain a product. The product was a viscous polymer. The ester value of the product was 12.1 mg KOH / g. The IR spectrum also showed a C=O stretching band at 1735 cm -1 , C(=O)O- antisymmetric stretching 1561cm -1 , and the C(=O)-NC(=O) stretching at 1709 and 1772 cm -1 The resulting product was designated block copolymer 3.

[0058] [Production Example 7: Synthesis of Block Copolymer 4] A stainless steel autoclave was charged with 1690 g of poly(iso)butenyl succinic anhydride (saponification value 36 mg KOH / g), 208 g of the amido alcohol ethylene oxide adduct (1) obtained in Production Example 2, and 13 g of the amido alcohol ethylene oxide adduct (2) obtained in Production Example 3. After thorough nitrogen purge and heating to 80°C, 64 g of 48% KOH and 21 g of potassium acetate were added. Further thorough nitrogen purge was performed and the mixture was heated to 160°C. The mixture was then maintained at 160°C under reduced pressure of 0.2 kPa or less with trace nitrogen bubbling for 5 hours to obtain a product. The resulting product was a viscous polymer. The ester value of the product was 8.4 mg KOH / g. IR spectrum revealed a C=O stretching band of 1735 cm. -1 , C(=O)O- antisymmetric stretching 1561cm -1 , and the C(=O)-NC(=O) stretching at 1709 and 1772 cm -1 The resulting product was designated block copolymer 4.

[0059] [Production Example 8: Preparation of acid-modified polypropylene] 9,700 parts of low-molecular-weight polypropylene with an Mn of 3,300 and an average number of terminal double bonds of 0.9 were melted at 220°C under a nitrogen gas atmosphere and reacted with 300 parts of maleic anhydride for 10 hours. The excess maleic acid was then removed under reduced pressure at 200°C for 4 hours to obtain a maleic anhydride-modified polypropylene (single-terminal acid-modified product). The Mn was 3,400, the saponification value was 30 mgKOH / g, and the degree of acid modification per molecule was 0.9.

[0060] [Production Example 9: Preparation of Block Copolymer 5] A stainless steel autoclave was charged with 4,000 g of the maleic anhydride-modified polypropylene prepared in Production Example 8, 750 g of the amido alcohol ethylene oxide adduct (1) obtained in Production Example 2, 46 g of the amido alcohol ethylene oxide adduct (2) obtained in Production Example 3, 13 g of antioxidant (Irganox 1010), 90 g of 48% NaOH, and 100 g of ionized water. After thorough nitrogen substitution, the mixture was heated to 220°C and stirred for 1 hour. The mixture was then maintained under reduced pressure of 2 kPa or less with trace nitrogen bubbling for 6 hours to obtain a product. The resulting product was easy to handle and a solid polymer. The ester value of the product was 7.5 mg KOH / g. IR spectroscopy revealed a C=O stretching band of 1737 cm. -1 , C(=O)O- antisymmetric stretching 1579cm -1 The resulting product was designated as block copolymer 5.

[0061] [Production Example 10: Preparation of Block Copolymer 6] A stainless steel autoclave was charged with 3100 g of poly(iso)butenyl succinic anhydride (saponification value 60 mg KOH / g), 1420 g of the amido alcohol ethylene oxide adduct (1) obtained in Production Example 2, and 70 g of the amido alcohol ethylene oxide adduct (2) obtained in Production Example 3. After thorough nitrogen purge, the mixture was heated to 80°C, after which 385 g of 48% KOH was added. Further, thorough nitrogen purge was performed, the mixture was heated to 160°C, and the mixture was maintained at 160°C under reduced pressure of 0.2 kPa or less with slight nitrogen bubbling for 5 hours to obtain a product. The resulting product was a viscous polymer. The ester value of the product was 7.9 mg KOH / g. Furthermore, IR spectroscopy revealed a C=O stretching band of 1735 cm. -1 , C(=O)O- antisymmetric stretching 1561cm -1 , and the C(=O)-NC(=O) stretching at 1709 and 1772 cm -1 The resulting product was designated block copolymer 6.

[0062] <Preparation of resin foam> Samples (masterbatches) of the resin compositions of Examples 1 to 6, 7 to 9, and Comparative Examples 1 to 4 described below were hot-press molded in a mold 25 mm in diameter and 1 mm thick at 10 MPa for 5 minutes in the range of 160 to 200°C to produce disc-shaped plates. The disc-shaped plates were then placed in a pressure-resistant sealed container and heated to a predetermined temperature (foaming temperature). Carbon dioxide was then injected as a foaming agent at a pressure of 15 MPa and maintained for 2 hours to allow impregnation. After 2 hours, the pressure was released to normal pressure to produce resin foams.

[0063] [Examples 1 to 7] 85 parts of a base polyolefin resin (polyethylene (PE) resin: Tosoh Corporation, trade name "Petrothene 221", or the PE resin and polypropylene (PP) resin: Japan Polypropylene Corporation, trade name "WAYMAX MFX8", the blending ratio is shown in Table 1) and 15 parts each of the block copolymers 1 to 6 were masterbatched in a twin-screw extruder at an extrusion temperature of 180°C. According to the above-mentioned <Preparation of Resin Foam>, a resin foam was obtained at a foaming temperature of 110°C. The produced resin foam was evaluated for bubbles using the evaluation method described below. The obtained results are shown in Table 1. Incidentally, an SEM photograph of the resin foam of Example 4 is shown in FIG.

[0064] [Examples 8 to 10] Polyolefin resin foams were prepared in the same manner as in Examples 1 to 7, except that the polyolefin resin (polyethylene (PE) resin: manufactured by Tosoh Corporation, trade name "Petrothene 221") and the block copolymer 1 were mixed in the amounts shown in Table 2, and the bubbles were evaluated. The results are also shown in Table 2. An SEM photograph of the resin foam of Example 10 is shown in FIG. 2.

[0065] [Comparative Examples 1 to 4] 99.9 parts of a base polyolefin resin (polyethylene (PE) resin: manufactured by Tosoh Corporation, trade name "Petrothene 221") and 0.1 parts each of Compound 1 or Compound 2, or talc or glass fiber as a foam nucleating agent, were masterbatched in a twin-screw extruder at an extrusion temperature of 180°C. According to the procedure described above in <Preparation of Resin Foam>, a resin foam was obtained at a foaming temperature of 110° C. The produced resin foam was evaluated for bubbles by the evaluation method described below. The obtained results are shown in Table 3.

[0066] [Evaluation of bubbles] <Expansion ratio of resin foam> The expansion ratio of the resin foam is determined by the specific gravity of the unfoamed composition (master batch) and the JIS K The apparent specific gravity of the foam was measured using an electronic specific gravity meter MDS-300 (manufactured by Alpha Mirage) in accordance with 7112.

[0067] <Average cell diameter of resin foam> The foam was cut, and the center of the cut surface was observed using a scanning electron microscope JSM-5310 (manufactured by JEOL Ltd.). The bubble diameters of 100 or more bubbles in the obtained image were measured using image analysis particle size distribution software Mac-View (manufactured by Mountec Co., Ltd.), and the average value was calculated to be the average bubble diameter of the resin foam.

[0068] <Closed cell ratio of resin foam> The closed cell ratio of the resin foam was measured in accordance with ASTM D-2856-87. The foam was divided into three equal parts in the width direction, and six samples measuring 10 mm x 10 mm were cut out from each of the three positions. The volume of the closed cell portion, excluding the open cell portion, was measured using an air comparison type hydrometer Model 1000 (Tokyo Science Co., Ltd.), and the closed cell ratio for each sample was calculated using the following formula. The average value (N=6) of these closed cell ratios was calculated and used as the closed cell ratio of the resin foam. Closed cell rate (%) = Closed cell volume (cm 3 ) / Apparent volume of foam (cm 3 ) x 100

[0069] <Bubble density of foam> The foam was cut, and the center of the cut surface was observed using a scanning electron microscope JSM-5310 (manufactured by JEOL Ltd.). The number of bubbles in the obtained image (measurement surface, N=100 or more) was counted using image analysis particle size distribution software Mac-View (manufactured by Mountech Co., Ltd.). The bubble number density was calculated using the following formula, and the average value was determined to be the bubble number density of the resin foam. N0=(n / A) 3 / 2 N0 is the bubble number density, n is the number of bubbles, and A is the total area of ​​the measurement surface.

[0070] <Bubble size distribution of foam> The foam was cut, and the center of the cut surface was observed using a scanning electron microscope JSM-5310 (manufactured by JEOL Ltd.). The bubble diameters of 100 or more bubbles in the obtained image were measured using image analysis particle size distribution software Mac-View (manufactured by Mountec Co., Ltd.), and the smallest visible bubble diameter (referred to as α) and the largest visible bubble diameter (referred to as β) were displayed as α to β, which was used to determine the bubble diameter distribution of the resin foam.

[0071] <Dissolution confirmation test> 10 g of the prepared resin foam was immersed in 200 ml of distilled water and left to stand in a 40°C warm bath for 6 hours to elute the chemicals (block copolymers and compounds) that had bled out onto the surface of the resin foam or to remove the foam nucleating agent. The resin foam was then removed and the distilled water was evaporated in an evaporator, and the presence or absence of elution or removal was confirmed from the residue. ○: No residue (elution or detachment) ×: Residue (elution or detachment)

[0072] [Table 1]

[0073] [Table 2]

[0074] [Table 3]

[0075] As shown in Examples 1 to 10, the foams containing block copolymers 1 to 7 had small average cell diameters, fine cells, a high closed cell ratio, a high cell density, and a homogeneous cell structure (see Figures 1 and 2). Furthermore, as shown in these examples, no residue was found in the elution test, confirming that a contaminated resin foam was obtained.

[0076] On the other hand, as shown in Comparative Examples 1 to 4, compounds 1 and 2 (Comparative Examples 1 and 2) did not produce foams, and foam nucleating agents A and B (Comparative Examples 3 and 4) produced foams with a non-uniform cell structure, with a high expansion ratio but a large average cell diameter of over 100 μm, a closed cell ratio of only 85% at most, and a cell number density that was one order of magnitude lower than that of the Examples.

[0077] From the above results, it was confirmed that the present invention can provide a polyolefin resin foam having a uniform cell structure and low contamination.

[0078] The polyolefin resin foam of the present invention can be suitably used for various applications such as food containers, automobile parts, and packaging materials for electronic parts by thermoforming into various shapes.

Claims

1. A polyolefin resin foam containing a block copolymer (A) represented by the following general formula (1) or general formula (2): A polyolefin resin foam, wherein, in a scanning electron microscope image of the central portion of a cross section of the foam, the smallest visible bubble diameter is 18 μm and the largest bubble diameter is 50 μm among 100 or more bubbles. 【Chemistry 1】 (In the formula, R １ is a polyolefin residue, A １ represents a divalent group having a polyoxyalkylene group, X １ is -O- or -N(R ２ )-(wherein, R ２ represents a hydrogen atom or an alkyl group, alkenyl group or acyl group having 1 to 22 carbon atoms; B １ represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group, an aryl group, an alkylaryl group, an acyl group, or a structure represented by the following formula (3) or (4), M １ represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, an ammonium group, or an organic ammonium group. 【Chemistry 2】 (In the formula, R ３ is a polyolefin residue, A ２ represents a divalent group having a polyoxyalkylene group, B ２ represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group, an aryl group, an alkylaryl group, an acyl group, or a structure represented by the following formula (3) or (4): 【Transformation 3】 (In the formula, R ４ is a polyolefin residue, X ２ is -O- or -N(R ５ )-(wherein, R ５ represents a hydrogen atom or an alkyl group, alkenyl group or acyl group having 1 to 22 carbon atoms; M ２ represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, an ammonium group, or an organic ammonium group. 【Chemistry 4】 (In the formula, R ６ represents a polyolefin residue.)

2. A polyolefin resin foam containing a block copolymer (A) represented by the following general formula (1) or general formula (2), and having an average cell diameter of 10 to 100 μm: 【Transformation 5】 (wherein R 1 is a polyolefin residue, A 1 is a divalent group having a polyoxyalkylene group, X 1 is —O— or —N(R 2 )— (wherein R 2 is a hydrogen atom or an alkyl group, alkenyl group or acyl group having 1 to 22 carbon atoms), B 1 is a hydrogen atom, an alkyl group, alkenyl group, aryl group, alkylaryl group or acyl group having 1 to 30 carbon atoms, or a structure represented by the following formula (3) or (4), and M 1 is a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, an ammonium group or an organic ammonium group.) 【Transformation 6】 (In the formula, R 3 represents a polyolefin residue, A 2 represents a divalent group having a polyoxyalkylene group, and B 2 represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group, an aryl group, an alkylaryl group, an acyl group, or a structure represented by the following formula (3) or (4).) 【Transformation 7】 (wherein R 4 represents a polyolefin residue, X 2 represents —O— or —N(R 5 )— (wherein R 5 represents a hydrogen atom or an alkyl, alkenyl or acyl group having 1 to 22 carbon atoms), and M 2 represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, an ammonium group or an organic ammonium group.) 【Transformation 8】 (wherein R 6 represents a polyolefin residue.)

3. A polyolefin resin foam containing a block copolymer (A) represented by the following general formula (1) or general formula (2) and having a closed cell rate of 70% or more: 【Chemistry 9】 (wherein R 1 is a polyolefin residue, A 1 is a divalent group having a polyoxyalkylene group, X 1 is —O— or —N(R 2 )— (wherein R 2 is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms) B 1 represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, an alkylaryl group, an acyl group having 1 to 30 carbon atoms, or a structure represented by the following formula (3) or (4), and M 1 represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, an ammonium group, or an organic ammonium group. 【Chemistry 10】 (In the formula, R 3 represents a polyolefin residue, A 2 represents a divalent group having a polyoxyalkylene group, and B 2 represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group, an aryl group, an alkylaryl group, an acyl group, or a structure represented by the following formula (3) or (4).) 【Chemistry 11】 (wherein R 4 represents a polyolefin residue, X 2 represents —O— or —N(R 5 )— (wherein R 5 represents a hydrogen atom or an alkyl, alkenyl or acyl group having 1 to 22 carbon atoms), and M 2 represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, an ammonium group or an organic ammonium group.) 【Chemistry 12】 (wherein R 6 represents a polyolefin residue.)

4. R in the general formula (1) １ The polyolefin resin foam according to any one of claims 1 to 3, wherein is a polyisobutylene residue.

5. R in the general formula (1) １ and R in the general formula (3) ４ The polyolefin resin foam according to any one of claims 1 to 3, wherein is a polyisobutylene residue.

6. R in the general formula (2) ３ and R in the general formula (4) ６ The polyolefin resin foam according to any one of claims 1 to 3, wherein is a polyisobutylene residue.

7. A in the general formula (1) １ and A2 in the general formula (2) is -(R ８ O) ｍ -R ７ - (OR ９ ) ｎ - (wherein, R ７ is a divalent organic group having 1 to 30 carbon atoms, R ８ , R ９ each independently represent an alkylene group having 2 to 4 carbon atoms, and m and n each independently represent an integer of 1 to 100.

8. A in the general formula (1) １ is a polyoxyalkylene group, and X １ -N (R ２ )-(wherein, R ２ represents an acyl group having 1 to 22 carbon atoms.

9. 4. The polyolefin resin foam according to claim 1, comprising 0.1 to 20 parts by mass of the block copolymer (A) per 100 parts by mass of the polyolefin resin.

10. A molded article obtained by molding the polyolefin resin foam according to any one of claims 1 to 9.

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