JP2016037552A - Water-crosslinkable resin composition as well as foamed body and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-crosslinkable polyolefin composition that can achieve an improvement in heat resistance and flame retardancy without decreasing the expansion ratio.SOLUTION: A water-crosslinkable resin composition is prepared by combining silyl-modified polyolefin and a flame retardant comprising halogen-based flame retardant having acid anhydride group and/or imide group. The halogen-based flame retardant may be halogenated phthalic acid anhydride and/or Calkylene bis-halogenated isoindoline dione. The proportion of the flame retardant may be at a level of 1 to 40 pts.wt. per 100 pts.wt. of silyl-modified polyolefin. The inventive composition may further contain a flame retardant auxiliary (in particular antimony-based flame retardant auxiliary). A foamed body may be produced by first foam-forming the composition and then water-crosslinking the silyl-modified polyolefin with help of the water in the air.SELECTED DRAWING: None

Description

  The present invention relates to a water-crosslinkable polyolefin composition capable of foaming at a high foaming ratio and excellent in heat resistance and flame retardancy, a foam (particularly a closed-cell foam) formed from this composition, and a method for producing the same. .

  Silyl-modified polyolefins obtained by graft polymerization of silyl compounds such as trialkoxysilylethene onto polyolefins can be easily crosslinked with water in the air after molding (water-crosslinking) and can improve heat resistance. Has been.

  Japanese Patent Application Laid-Open No. S48-1000047 (Patent Document 1) discloses a foamable composition containing a silyl-modified polyethylene or copolymer, a foaming agent and a siloxane condensation catalyst. In the examples of this document, azodicarbonamide is blended as the foaming agent.

  However, with this composition, it is difficult to improve the expansion ratio. Furthermore, since azodicarbonamide is used as a foaming agent, harmful effects (for example, corrosion of copper pipes, etc.) due to organic acids such as formic acid and acetic acid generated by decomposition, ammonia, and the like occur depending on applications.

  JP-A-60-55036 (Patent Document 2) discloses that 100 parts by weight of a silyl-modified polyolefin resin, 3 to 15 parts by weight of decabromodiphenyl ether and / or hexabromobenzene, antimony trioxide and / or five parts. 1-15 parts by weight of antimony oxide is mixed, heated and melted in an extruder, mixed with low-boiling hydrocarbon gas, extruded and foamed from a mold, and difficult to crosslink to a gel content of 5 to 90% with moisture in the atmosphere A method for producing a flammable foam is disclosed. In the examples of this document, decabromodiphenyl ether and antimony trioxide are blended in a weight ratio of the former / the latter = 2/1.

  However, since this composition also contains a flame retardant, it is difficult to improve the expansion ratio.

  In JP-A-2006-199760 (Patent Document 3), a foaming agent is supplied to a kneaded product containing a low-density polyethylene grafted with trialkoxysilylethene and an organic flame retardant, and then extruded and foamed. In the method for producing a flame retardant resin foam, a method is disclosed in which a flame retardant having a melting temperature equal to or lower than the melting temperature of the polyethylene is used as the organic flame retardant. This document describes an organic halogen compound containing bromine and / or chlorine as the organic flame retardant, and chlorinated paraffin is used in the examples. Further, it is described that an inorganic antimony compound may be blended in a weight ratio of 1/7 to 2/3 with respect to an organic flame retardant as a flame retardant aid. In the examples, organic flame retardant / flame retardant aid is described. Agents are blended at a weight ratio of 2/1. Furthermore, shrinkage inhibitors such as higher fatty acid esters and higher fatty acid amides are described as additives, and in the examples, stearic acid monoglyceride is used.

  However, even with this composition, it is difficult to improve the expansion ratio. In addition, the heat resistance of the resin decreases due to the plasticizing effect of the flame retardant. Further, when chlorinated paraffin is used, hydrogen chloride generated during extrusion molding is included in the resin, and harmful effects (for example, corrosion of copper piping, etc.) occur depending on the application.

Japanese Patent Application Laid-Open No. 48-100500 (claims, examples) JP-A-60-55036 (Claims, Examples) JP 2006-199760 A (Claims, paragraph [0030], Examples)

  Accordingly, an object of the present invention is to provide a water-crosslinkable polyolefin composition capable of improving heat resistance and flame retardancy without lowering the expansion ratio, a foam formed from this composition, and a method for producing the same. is there.

  Another object of the present invention is to provide a water-crosslinkable polyolefin composition capable of improving surface smoothness, a foam formed from the composition, and a method for producing the same.

  Still another object of the present invention is to provide a water-crosslinkable polyolefin composition capable of forming a foam capable of suppressing generation of harmful components and gelation even by foam molding, a foam formed from the composition, and a method for producing the same. Is to provide.

  As a result of diligent study to achieve the above-mentioned problems, the present inventors foamed a water-crosslinkable silyl-modified polyolefin by adding a halogen-based flame retardant having an acid anhydride group and / or an imide group as a flame retardant. It has been found that foaming can be performed at a high expansion ratio even if it is molded, and the present invention has been completed.

That is, the water-crosslinkable resin composition of the present invention includes a silyl-modified polyolefin and a flame retardant including a halogen-based flame retardant having an acid anhydride group and / or an imide group. The halogen flame retardant may contain an aromatic ring or an aliphatic ring. The halogen flame retardant may be halogenated phthalic anhydride and / or C _1-10 alkylene bis-halogenated isoindoline dione. The ratio of the flame retardant may be about 1 to 40 parts by weight with respect to 100 parts by weight of the silyl-modified polyolefin. The composition of the present invention may further contain a flame retardant aid (particularly an antimony flame retardant aid). The weight ratio of the flame retardant to the flame retardant aid is about the former / the latter = 85/15 to 45/55. The composition of the present invention may further contain a foaming agent (particularly a volatile foaming agent). The composition of the present invention may further contain a crosslinking accelerator. The silyl-modified polyolefin may be a polymer obtained by graft polymerization of a silyl compound having a hydrolytic condensable group and an ethylenically unsaturated bond to a polyolefin. The composition of the present invention preferably contains substantially no additive having a group capable of reacting with a hydrolytic condensable group.

  The present invention also includes a foam formed from the composition. The foam of the present invention may have a gel fraction measured by a method of extracting with xylene at 135 ° C. for 8 hours for 50% by weight or more. The foam of the present invention may have an expansion ratio of 10 times or more.

  The present invention also includes a foam production method including a foaming step of foam-molding the composition and a crosslinking step of crosslinking the foam-molded composition. In the cross-linking step, the silyl-modified polyolefin may be cross-linked with water in the air.

  In the present invention, since a halogen-based flame retardant having an acid anhydride group and / or an imide group is blended as a flame retardant, the heat resistance and flame retardancy can be improved without reducing the expansion ratio. Moreover, the smoothness of the foam surface can also be improved. Furthermore, by combining a fatty acid amide and a volatile foaming agent, harmful components and gelation can be suppressed even when foamed by extrusion foaming.

[Water crosslinkable resin composition]
The water-crosslinking (moisture curable) resin composition of the present invention contains a silyl-modified polyolefin and a halogen flame retardant having an acid anhydride group and / or an imide group.

(Sily modified polyolefin)
The silyl-modified polyolefin may be a polyolefin having a hydrolyzable hydrolyzable silyl group (water-crosslinkable silyl group), and has a hydrolyzable condensable silyl group as a monomer constituting the main chain. A polymer obtained by using a monomer may be used, or a polymer obtained by graft polymerization of a monomer having a hydrolytic condensable silyl group on the polyolefin main chain may be used. Among these, from the viewpoint of crosslinkability and productivity, a polymer obtained by graft polymerization of a silyl compound having a hydrolytic condensable group and an ethylenically unsaturated bond to polyolefin is preferable.

Examples of the hydrolytic condensable silyl group include a hydroxysilyl group; a trihalosilyl group such as trichlorosilyl; a C _1-4 alkyldihalosilyl group such as methyldichlorosilyl; an aryl dihalosilyl group such as phenyldichlorosilyl; Di-C _1-4 alkylhalosilyl groups such as chlorosilyl; Tri-C _1-4 alkoxysilyl groups such as trimethoxysilyl and triethoxysilyl; Di-C _1-4 alkoxyC ₁ such as methyldimethoxysilyl and diethoxymethylsilyl _-4 alkylsilyl group; phenyl dimethoxy silyl, aryldi _{C 1-4} alkoxysilyl group such as phenyl diethoxy silyl; methoxydimethylsilyl, _{C 1-4} alkoxydi _{C 1-4} alkylsilyl group such as ethoxy dimethylsilyl; diphenylmethoxy Cyril Diaryl C _1-4 alkoxysilyl group such as diphenyl ethoxy silyl; phenyl methoxymethylsilyl, and aryl C _1-4 alkoxy C _1-4 alkylsilyl group such as phenyl ethoxymethyl silyl and the like. These silyl groups can be used alone or in combination of two or more. Of these silyl groups, tri C _1-4 alkoxysilyl groups such as trimethoxysilyl and triethoxysilyl are preferred.

Such hydrolytic condensable group (hydrolytic condensable silyl group) and a silyl compound having an ethylenically unsaturated bond, for example, trimethoxysilyl ethene, triethoxysilyl ethene, such as methyldimethoxysilyl ethene C _{1- 4} alkoxysilylethene; _C1-4 alkoxysilylpropene such as trimethoxysilylpropene, triethoxysilylpropene; _C1-4 alkoxysilylbutene such as trimethoxysilylbutene; _C1-4 alkoxysilyl such as trimethoxysilylcyclohexene cyclohexene; C _1-4 alkoxysilyl cyclopentadiene such as trimethoxysilyl cyclopentadiene; the silyl compound having a (meth) acryloyl groups, for example, trimethoxysilyl-2-ethyl methacrylate, tri Such as _{C 1-4} alkoxysilyl _{C 2-4} alkyl (meth) acrylates such as Tokishishiriru-3-propyl methacrylate. These silyl compounds can be used alone or in combination of two or more. Of these silyl compounds, C _1-4 alkoxysilylethene such as trimethoxysilylethene is preferred.

The polyolefin forming the main skeleton of the silyl-modified polyolefin includes an olefin homo- or copolymer. Examples of the olefin include α-C _2-10 olefins (preferably α-C) such as ethylene, propylene, 1-butene, isobutene, 4-methyl-1-butene, 1-pentene and 3-methyl-1-pentene. _2-8 olefins, more preferably α-C _2-4 olefins). These olefins may be used alone or in combination of two or more. Of these olefins, ethylene and / or propylene are preferably contained.

  The polyolefin may be a copolymer of an olefin and a copolymerizable monomer. Examples of the copolymerizable monomer include polymerizable nitrile compounds (for example, (meth) acrylonitrile), (meth) acrylic monomers (for example, methyl (meth) acrylate, ethyl (meth) acrylate, etc. (Meth) acrylic acid esters, (meth) acrylic acid etc.), unsaturated dicarboxylic acids or derivatives thereof (maleic anhydride etc.), vinyl esters (eg vinyl acetate, vinyl propionate etc.), conjugated dienes ( Examples thereof include butadiene and isoprene. A copolymerizable monomer can be used individually or in combination of 2 or more types. The ratio of the copolymerizable monomer is 0 to 50 mol%, preferably 0.1 to 30 mol%, more preferably about 1 to 10 mol% in all monomers.

  The copolymers (copolymers of olefins and copolymers of olefins and copolymerizable monomers) include random copolymers, alternating copolymers, block copolymers, and graft copolymers. Usually, it is a random copolymer or an alternating copolymer.

These polyolefins can be used alone or in combination of two or more. Among these polyolefins, poly _C2-3 olefin resins (especially polyethylene resins) such as polyethylene resins and polypropylene resins are preferable from the viewpoint of foamability.

  Examples of the polyethylene resin include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene-propylene copolymer, ethylene-butene- 1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene- (4-methylpentene-1) copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, and the like. These polyethylene resins can be used alone or in combination of two or more. Of these polyethylene resins, LDPE, LLDPE, ethylene-vinyl acetate copolymer, and the like are preferable from the viewpoint of foamability.

  The number average molecular weight of the polyethylene resin may be about 10,000 to 300,000, preferably about 15,000 to 200,000, and more preferably about 20,000 to 100,000. The molecular weight is a universal calibration based on polystyrene, using a gel permeation chromatography method (GPC method) at a measurement temperature of 140 ° C., using orthodichlorobenzene as a solvent and a column (Shodex GPC AD-806MS). Can be measured.

  The melt flow rate (MFR) of the polyethylene resin is a method according to JIS K 7210 (190 ° C., load 21.2 N), for example, 0.1 to 20 g / 10 minutes, preferably 0.3 to 10 g / 10. Min, more preferably about 0.5 to 5 g / 10 min (particularly about 0.6 to 3 g / 10 min). If the MFR is too small or conversely too large, the foamability and strength may be reduced.

  The melting point or softening point of the polyethylene resin may be 80 to 150 ° C, preferably 90 to 140 ° C, and more preferably about 100 to 130 ° C.

  Examples of the polypropylene resin include polypropylene, propylene-ethylene copolymer, propylene- (meth) acrylic acid copolymer, propylene-ethylene-butene-1. These polypropylene resins can be used alone or in combination of two or more. Of these polypropylene resins, polypropylene, propylene-ethylene copolymer and the like are preferable.

  The number average molecular weight of the polypropylene resin may be about 10,000 to 500,000, preferably about 15,000 to 300,000, and more preferably about 20,000 to 100,000. The number average molecular weight of the polypropylene resin can be measured by a gel permeation chromatography method (GPC method). The number average molecular weight of the polypropylene resin can be measured under the same conditions as the method for measuring the number average molecular weight of the polyethylene resin.

  The melting point or softening point of the polypropylene resin may be about 120 to 180 ° C, preferably about 130 to 175 ° C, and more preferably about 140 to 170 ° C.

  The MFR of the polypropylene resin is a method according to JIS K 7210 (230 ° C., load 21.2 N), for example, 0.1 to 20 g / 10 minutes, preferably 0.3 to 10 g / 10 minutes, more preferably It is about 0.5-8 g / 10 minutes (especially 1-5 g / 10 minutes). If the MFR is too small or conversely too large, the foamability and strength may be reduced.

  The ratio of the silyl compound having a hydrolytic condensable group and an ethylenically unsaturated bond is, for example, 0.1 to 30 parts by weight, preferably 0.5 to 10 parts by weight (for example 1 to 100 parts by weight) with respect to 100 parts by weight of the polyolefin. 8 parts by weight), more preferably about 2 to 6 parts by weight (particularly 3 to 5 parts by weight). If the ratio of the silyl compound is too small, the crosslinking density may be reduced and the heat resistance may be reduced. If the ratio is too large, the expansion ratio may be reduced.

  When the silyl compound is graft polymerized with polyolefin, a conventional radical polymerization initiator may be added. Examples of the radical polymerization initiator include organic peroxides [diacyl peroxide, peroxy ester, dialkyl peroxide (for example, dicumyl peroxide, t-butylcumyl peroxide, 1,1-di-butylperoxy- 3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexane, 1,3-bis (t-butylperoxy-isopropyl) benzene, di-t- Butyl peroxide, etc.)], inorganic peroxides (for example, hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, etc.). These radical polymerization initiators can be used alone or in combination of two or more. Of these, organic peroxides such as dialkyl peroxide are widely used.

  The ratio of the radical polymerization initiator is, for example, 0.01 to 5 parts by weight, preferably 0.03 to 3 parts by weight, and more preferably 0.05 to 1 part by weight (particularly 0.1 to 100 parts by weight of polyolefin). 1 to 0.5 parts by weight).

  In the polymerization, a conventional additive (such as a polymerization inhibitor) may be further contained.

  As a method of graft polymerization, for example, a method of heating and polymerizing by melt kneading is preferable. The polymerization temperature may be any temperature that can soften the polyolefin, and can be selected according to the type of polyolefin, for example, 80 to 300 ° C, preferably 100 to 250 ° C, more preferably 150 to 230 ° C (particularly 160 to 220 ° C). Degree).

(Flame retardants)
A flame retardant contains the halogenated flame retardant which has an acid anhydride group and / or an imide group from the point which can suppress the fall of an expansion ratio. The halogen-based flame retardant may have a halogen atom and an acid anhydride group and / or an imide group. Usually, the halogen atom is a chlorine atom or a bromine atom, and is an aromatic ring or an aliphatic ring. It is preferable that (especially the aromatic ring) has an acid anhydride group and / or an imide group.

Examples of the aromatic ring (arene) include C _6-20 arenes such as benzene and naphthalene. Examples of the aliphatic ring include hydrogenated products thereof, for example, hydrogenated C _6-20 arenes such as cyclohexane and hydrogenated naphthalene. Of these, C _6-10 arenes such as benzene are preferred from the viewpoint of flame retardancy.

The number of acid anhydride groups and / or imide groups is not particularly limited as long as it is 1 or more in the molecule, and is, for example, 1 to 10, preferably 1 to 5, more preferably 1 to 3 (particularly 1 to 2). Degree. The imide group may form a bismaleimide skeleton by being linked by an alkylene group. Examples of the alkylene group as the linking group of the imide group include a C _1-10 alkylene group such as ethylene (particularly a C _2-4 alkylene group).

  The number of halogen atoms in the molecule can be selected according to the number of aromatic rings or aliphatic rings. For example, it is sufficient that at least some of the hydrogen atoms in the hydrocarbon are substituted with halogen atoms, but flame retardancy From the standpoint of improving the above, a perhalohydrocarbon group in which all substitutable hydrogen atoms are substituted with halogen atoms is preferable. Specifically, the number of halogen atoms in the molecule is, for example, about 1 to 30, preferably about 3 to 20, and more preferably about 5 to 15 (particularly 6 to 10).

Examples of the halogen-based flame retardant having an acid anhydride group and / or an imide group include halogenated phthalic anhydrides such as tetrachlorophthalic anhydride and tetrabromophthalic anhydride, or hydrogenated products thereof; 2,2′-ethylenebis (Tetrachloroisoindolinedione), C _1-10 alkylenebishalogenated isoindolinedione such as 2,2′-ethylenebis (tetrabromoisoindolinedione) or hydrogenated product thereof. These halogen-based flame retardants can be used alone or in combination of two or more. Among these halogen flame retardants, C _1-6 alkylene bis such as brominated phthalic anhydride such as tetrabromophthalic anhydride and 2,2′-ethylenebis (tetrabromoisoindolinedione) from the viewpoint of safety. Brominated indoline diones are preferred, and C _2-4 alkylene bis brominated isoindoline diones such as ethylene bistetrabromoisoindoline dione are particularly preferred from the viewpoint that the expansion ratio can be improved.

  The ratio of the halogen-based flame retardant is, for example, 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more (particularly 90% by weight or more) with respect to the entire flame retardant. It is preferable that the material substantially consists of the halogen-based flame retardant. If the proportion of the halogen flame retardant is too small, the expansion ratio may be reduced.

  The flame retardant may contain other flame retardants as long as the expansion ratio is not lowered. Other flame retardants include conventional flame retardants such as inorganic flame retardants such as boric acid flame retardants and phosphorus flame retardants; organic flame retardants such as nitrogen flame retardants and other halogen flame retardants. Can be mentioned. These flame retardants can be used alone or in combination of two or more. Of these flame retardants, organic flame retardants, particularly other halogen flame retardants, are preferred from the viewpoint of excellent flame retardancy. Other halogen flame retardants usually include chlorine flame retardants and bromine flame retardants.

  Chlorinated flame retardants include, for example, aliphatic chlorinated products such as chlorinated alkanes and chlorinated paraffins; alicyclic chlorinated products such as chlorinated cycloalkanes (such as chlorinated pentacyclodecane); chlorinated arenes (chlorine) Chlorinated phthalic anhydrides such as chlorinated naphthalene and tetrachlorophthalic anhydride), chlorinated bisarenes (such as chlorinated biphenyls, chlorinated bisphenols such as tetrachlorobisphenol A), chlorinated aromatic polymers (chlorinated polyphenyls) And aromatic chlorinated products such as chlorinated polystyrene. These chlorinated flame retardants can be used alone or in combination of two or more.

Examples of brominated flame retardants include brominated alkanes (tetrabromoethane, tetrabromobutane, etc.), aliphatic brominated products such as brominated paraffins; brominated cycloalkanes (brominated cyclodecanes such as hexabromocyclodecane, etc.) Brominated arenes (brominated benzenes such as hexabromobenzene, brominated phthalic anhydrides such as brominated naphthalene and tetrabromophthalic anhydride), brominated bisarenes (brominated biphenyl, deca Brominated diphenyl ethers such as bromodiphenyl ether, brominated bisphenols such as tetrabromobisphenol A, C _1-10 alkylene bis brominated benzenes such as ethylene bispentabromobenzene (ethane-diyl-bis-pentabromobenzene), bromine Aromatic poly Aromatic bromides such as mer (brominated epoxy resins such as tetrabromobisphenol A type epoxy resin, brominated bisphenol type phenoxy resin, brominated polystyrene, brominated polycarbonate, brominated polyphenylene oxide, etc.). These brominated flame retardants can be used alone or in combination of two or more.

  The ratio of the other flame retardant is, for example, 50% by weight or less, preferably 40% by weight or less (eg 1 to 40% by weight), more preferably 30% by weight or less (eg 10 to 30% by weight) with respect to the whole flame retardant. %) Degree. If the ratio of the other flame retardant is too large, the expansion ratio may decrease.

  The ratio of the flame retardant (particularly the halogen flame retardant) is, for example, 1 to 40 parts by weight, preferably 5 to 30 parts by weight (for example 6 to 20 parts by weight), more preferably 100 parts by weight of the silyl-modified polyolefin. It is about 8 to 15 parts by weight (particularly 9 to 13 parts by weight). If the proportion of the flame retardant is too large, the foamability and mechanical properties are likely to be lowered, and if too small, the flame retardancy may be lowered. The proportion of the halogen-based flame retardant is a relatively larger proportion than that of a normal resin because the flame retardancy of the silyl-modified polyolefin is low.

(Flame retardant aid)
The flame retardant may be further combined with a flame retardant aid. The flame retardant aid includes an antimony compound (such as antimony oxide), a tin compound (such as tin oxide), a zirconium compound (such as zirconium oxide) and the like, and usually an antimony flame retardant aid is used.

Examples of antimony flame retardant aids include antimony oxide (antimony trioxide, antimony pentoxide, etc.), antimonate (metal antimonate such as sodium antimonate and magnesium antimonate, ammonium antimonate, etc.) Can be mentioned. Among these antimony compounds, antimony oxide such as antimony trioxide Sb ₂ O ₃ and / or xNa ₂ O.Sb ₂ O ₅ .yH ₂ O (x = 0 to 1, y = 0 to 4) is preferable. These antimony compounds can be used alone or in combination of two or more.

  The average particle diameter of the antimony flame retardant aid is, for example, 0.01 to 5 μm, preferably 0.05 to 4 μm, and more preferably about 0.1 to 3 μm. Moreover, you may surface-treat the surface of an antimony type flame retardant adjuvant with surface treating agents, such as an epoxy compound, a silyl compound, an isocyanate compound, a titanate compound.

  The weight ratio of the halogen flame retardant and flame retardant aid (particularly antimony flame retardant aid) is the former / the latter = 85/15 to 45/55, preferably 80/20 to 50/50, more preferably. It is about 75/25 to 55/45 (especially 70/30 to 60/40). If the ratio of the flame retardant aid is too small, the flame retardancy tends to be lowered, and if it is too much, the flame retardancy may be lowered.

  The ratio of the flame retardant aid is, for example, 1 to 25 parts by weight, preferably 2 to 20 parts by weight (eg 3 to 15 parts by weight), more preferably 4 to 10 parts by weight (100 parts by weight based on 100 parts by weight of the silyl-modified polyolefin. Particularly about 5 to 8 parts by weight).

(Fatty acid amide)
The water-crosslinkable resin composition of the present invention may further contain a fatty acid amide from the viewpoint that the foaming of the silyl-modified polyolefin can prevent shrinkage and improve the foaming ratio of the foam.

Examples of the fatty acid amide include _C10-24 saturation such as capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, isostearic acid amide, arachidic acid amide (eicosanoic acid amide), and behenic acid amide. Fatty acid amide; myristoleic acid amide, palmitoleic acid amide, petrothelic acid amide, oleic acid amide, linoleic acid amide, linolenic acid amide, ricinoleic acid amide, elaidic acid amide, gatrenic acid amide, arachidonic acid amide, erucic acid amide, brassic acid C _10-24 unsaturated fatty acids such as amide amide; methylene bis-lauric acid amide, methylene bis-stearic acid amide, ethylene Bisuka prills acid amide, et Lenbiscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bisisostearic acid amide, ethylene bisbehenic acid amide, tetramethylene bisstearic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide C _1-10 alkylene bis C _8-24 saturated fatty acid amides such as; C _1-10 alkylene bis C _8-24 unsaturated fatty acid amides such as methylene bis oleic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide; N, Bisuama produced by reaction of the N'- distearyl adipic acid amide, N, N'- distearyl sebacic acid _{C 6-12} alkane dicarboxylic acid and a saturated _{C 8-24} higher amines such as amide De; N, N'- dioleyl adipic acid amide, N, etc. bisamide formed by the reaction of _{C 6-12} alkane dicarboxylic acid with an unsaturated _{C 8-24} higher amines such as N'- dioleyl sebacic acid amide is Can be mentioned.

These fatty acid amides can be used alone or in combination of two or more. Among these fatty acid amides, C, such as lauric acid amide, stearic acid amide, palmitic acid amide, stearic acid amide, isostearic acid amide, arachidic acid amide (eicosanoic acid amide), behenic acid amide, etc. C _1-4 alkylene bis C _10-18 saturated fatty acid amides such as _12-18 saturated fatty acid amide and ethylene bis stearic acid amide are preferred.

  The ratio of the fatty acid amide is, for example, 0.05 to 20 parts by weight, preferably 0.1 to 18 parts by weight (for example, 0.2 to 15 parts by weight), more preferably 0 with respect to 100 parts by weight of the silyl-modified polyolefin. About 5 to 10 parts by weight (particularly 1 to 5 parts by weight). If the ratio of the fatty acid amide is too small, the expansion ratio may not be improved, and if it is too large, the mechanical properties may be deteriorated.

(Foaming agent)
The water-crosslinkable resin composition of the present invention may further contain a foaming agent. The foaming agent is preferably a volatile foaming agent (physical foaming agent) because it can suppress the progress of water cross-linking during foaming, improve the foaming ratio, and does not produce harmful components depending on the application. Particular preference is given to volatile blowing agents which do not have groups which can react with groups (especially hydroxyl groups).

  Examples of such volatile blowing agents include inert or non-flammable gases (nitrogen, carbon dioxide, chlorofluorocarbon, chlorofluorocarbon alternatives, etc.), organic physical blowing agents [for example, aliphatic hydrocarbons (propane, n-butane, Isobutane, pentane (n-pentane, isopentane, etc.), hexane (n-hexane, etc.), aromatic hydrocarbon (toluene, etc.), halogenated hydrocarbon (trichlorofluoromethane, etc.), ethers (dimethyl ether, petroleum Ethers, etc.), ketones (acetone, methyl ethyl ketone, etc.)] and the like. These volatile blowing agents can be used alone or in combination of two or more.

  Of these volatile blowing agents, organic physical blowing agents, particularly aliphatic hydrocarbons such as isobutane are preferred.

  The ratio of the blowing agent is, for example, about 1 to 30 parts by weight, preferably 2 to 25 parts by weight, more preferably 3 to 20 parts by weight (particularly 5 to 15 parts by weight) with respect to 100 parts by weight of the silyl-modified polyolefin. May be.

(Nuclear agent)
The water-crosslinkable resin composition of the present invention adsorbs gas generating components, makes the bubbles finer, makes the bubble film thinner, and improves the flexibility and surface smoothness. May further be included. The nucleating agent may be an organic nucleating agent such as citric acid, but is usually an inorganic nucleating agent. The form of the nucleating agent may be spherical, ellipsoidal, flat (such as flat), or indefinite.

  Inorganic nucleating agents include carbon materials (graphite, carbon black, etc.), metal silicates (calcium silicate, magnesium silicate, aluminum silicate, magnesium aluminosilicate, talc, clay, mica, diatomaceous earth, zeolite, kaolin, bentonite, smectite, Examples thereof include wollastonite, metal carbonates (calcium carbonate, sodium hydrogen carbonate, etc.), metal hydroxides (such as aluminum hydroxide), and metal oxides (silica, alumina, magnesium oxide, zinc oxide, etc.). These nucleating agents can be used alone or in combination of two or more. Of these nucleating agents, talc, calcium carbonate and silica are preferred.

The average diameter of the nucleating agent (such as an average particle diameter _{D 50) of,} for example, 25 [mu] m or less, preferably 0.1 to 20 [mu] m, more preferably may be about 0.3～18Myuemu, usually, 15 [mu] m or less (e.g., 0.5 to 10 μm). If the average diameter is too small, the effect of improving the foam properties is not sufficient, and if it is too large, foaming seems to be inhibited. The average diameter of the nucleating agent can be measured based on a laser diffraction method.

  The ratio of the nucleating agent is, for example, 0.1 to 10 parts by weight, preferably 0.2 to 8 parts by weight, more preferably 0.3 to 5 parts by weight (for example, 0 to 100 parts by weight of the silyl-modified polyolefin). About 5 to 3 parts by weight).

(Crosslinking accelerator)
The water-crosslinkable resin composition of the present invention may further contain a crosslinking accelerator (silanol condensation catalyst) for promoting water crosslinking.

  As the crosslinking accelerator, a conventional silanol condensation catalyst such as an organic acid, an inorganic acid, an amine, an organometallic compound, or the like can be used.

  Examples of the organic acid include aliphatic monocarboxylic acids such as acetic acid, caprylic acid and stearic acid; aliphatic dicarboxylic acids such as maleic acid; alicyclic carboxylic acids such as naphthenic acid; arene stearic acid such as toluenesulfonic acid Is mentioned. The organic acid may be an alicyclic monocarboxylic acid metal salt such as stannous acetate, stannous caprylate or zinc caprylate, or an alicyclic carboxylic acid metal salt such as cobalt naphthenate or lead naphthenate. Good.

  Examples of inorganic acids include hydrochloric acid and sulfuric acid. The inorganic acid may be an inorganic acid metal salt such as tin sulfate.

  Examples of amines include aliphatic amines such as ethylamine, dibutylamine and hexylamine, and cyclic amines such as pyridine.

  Examples of organometallic compounds include dialkyltin difatty acid esters such as dibutyltin diacetate, dibutyltin dicaprylate (octoate), dibutyltin dilaurate, dibutyltin dioleate, dibutyltin dicaprylate, dioctyltin dilaurate, and dioctyltin dioleate; Examples include titanic acid alkyl esters such as butyl ester and titanic acid tetranoniel ester.

These crosslinking accelerators can be used alone or in combination of two or more. Among these, a crosslinking accelerator containing tin is preferable from the viewpoint of high crosslinking promotion ability, and a di-C _4-12 alkyl tin C _2-18 fatty acid ester such as dioctyltin dilaurate is particularly preferable.

  The proportion of the crosslinking accelerator is, for example, 0.001 to 2 parts by weight, preferably 0.002 to 1 part by weight, more preferably 0.003 to 0.6 parts by weight (100 parts by weight of silyl-modified polyolefin). In particular, it is about 0.005 to 0.4 parts by weight. When the ratio of the crosslinking accelerator is too small, the progress of water crosslinking is slowed, and when it is too large, the expansion ratio may be lowered.

(Other additives)
The water-crosslinkable resin composition of the present invention may further contain a conventional additive added to the foamable composition. Examples of conventional additives include other shrinkage inhibitors other than fatty acid amide (for example, nonionic surfactants such as polyoxyethylene phenyl ether), other resin components, or thermoplastic elastomers (for example, the above-mentioned silyl-modified products). Polyolefins, olefinic elastomers, etc.), fillers (glass fillers such as glass fibers and carbon fibers), stabilizers (antioxidants such as hindered phenolic antioxidants); UV absorbers, heat stabilizers, weather resistance Stabilizers, etc.), foaming aids, colorants (dyes, pigments, etc.), dispersants, mold release agents, antifogging agents, lubricants, lubricants, impact modifiers, plasticizers, antishrink agents, antistatic agents, anti Examples include blocking agents, antibacterial agents, antiseptics, antifungal agents, photocatalysts (such as titanium oxide), heavy metal deactivators (such as copper damage inhibitors), and the like. These additives can be used alone or in combination of two or more. The ratio of these additives is 0.01 to 20 parts by weight, preferably 0.05 to 10 parts by weight, and more preferably about 0.1 to 5 parts by weight with respect to 100 parts by weight of the silyl-modified polyolefin.

  Among these additives, from the viewpoint that the crosslinking reaction proceeds excessively during foam molding and does not inhibit foaming, a group that can react with a hydrolytic condensable group (or such a group can be easily decomposed to form such a group). The group which generate | occur | produces, for example, the additive which does not contain an ester group and a hydroxyl group substantially, The additive (foaming agents, such as a degradable foaming agent, an anti-shrink agent, etc.) which does not contain a hydroxyl group is especially preferable.

(Method for producing water-crosslinkable resin composition)
The water-crosslinkable resin composition can be produced by mixing (or kneading) the constituent components by a conventional method. The water-crosslinkable resin composition is, for example, a dry blend (usually using a mixer such as a tumbler or a V-type blender) that is simply mixed in a granular or pellet form without melting and kneading the constituent components at room temperature. May be prepared by melting and kneading the constituent components (for example, silyl-modified polyolefin, fatty acid amide, nucleating agent, etc.). In a typical method, if necessary, components are premixed in a mixer (such as a tumbler, a V-type blender, a Henschel mixer, a Nauta mixer, a ribbon mixer, a mechanochemical apparatus, and an extrusion mixer), and then various melt kneaders ( For example, melt kneading is often performed using a kneader, a single screw or a twin screw extruder, or the like. The melt kneading temperature may be, for example, 150 to 300 ° C, preferably 160 to 280 ° C, and more preferably about 170 to 250 ° C. In melt kneading, pressure may be applied, and the pressure is, for example, about 1 to 100 MPa, preferably 5 to 50 MPa, and more preferably about 10 to 30 MPa. The melt-kneaded product may be pelletized by a conventional pelletizing means (such as a pelletizer).

  In addition, when heat-polymerizing a silyl-modified polyolefin by melt-kneading, at least a part of the fatty acid amide and other additives (additives excluding foaming agents and crosslinking accelerators) are combined with the polyolefin and the silyl compound during the heat-polymerization. It may be added.

  Further, the crosslinking accelerator may be preliminarily blended with the polyolefin to prepare a master batch, and may be added to the silyl-modified polyolefin in the foaming step. In the master batch, the ratio of the crosslinking accelerator is, for example, about 0.1 to 50 parts by weight, preferably about 0.5 to 30 parts by weight, and more preferably about 1 to 10 parts by weight with respect to 100 parts by weight of the polyolefin. .

  Further, the resin composition or nucleating agent may be impregnated with a foaming agent, or the resin component may be preliminarily incorporated with the foaming agent by mixing the resin component, the nucleating agent, and the foaming agent. A foaming agent may be added or injected into the product.

[Foam]
The foam of the present invention is formed of the water-crosslinkable resin composition, and the expansion ratio can be selected from 1.1 times or more (for example, about 1.5 to 100 times). ), A foam having a high expansion ratio of 10 times or more can be prepared. Specifically, the expansion ratio of the foam may be, for example, about 3 to 80 times, preferably about 5 to 60 times, and more preferably about 10 to 50 times (particularly about 20 to 40 times).

The density (apparent density) of the foam of the present invention is, for example, 0.01 to 0.1 g / cm ³ , preferably 0.012 to 0.08 g / cm ³ , more preferably 0.00 according to JIS K6767. It is about 015 to 0.05 g / cm ³ (particularly 0.02 to 0.04 g / cm ³ ). If the apparent density is too small, the rigidity tends to decrease and become brittle. If the apparent density is too large, the rigidity increases and the softness tends to decrease.

  The cell structure of the foam of the present invention may be an open cell structure, a closed cell structure, a structure in which these structures are mixed, or the like, but from the viewpoint of productivity, the closed cell structure is preferable. The closed cell ratio of the foam may be 80% by volume or more (for example, 80 to 100% by volume), preferably 83 to 99% by volume, and more preferably about 85 to 98% by volume. The average thickness of the diaphragm (or partition wall) of the foam cell is about 0.1 to 40 μm, preferably about 0.3 to 30 μm, and more preferably about 0.4 to 20 μm.

  In addition, the average thickness of the diaphragm of a foam cell can be measured by the method of measuring using an optical microscope photograph etc., the method of measuring using the following formula | equation, etc.

  The shape (or cross-sectional shape) of the closed cell is not particularly limited and may be an indefinite shape, but is usually a circular shape (for example, a perfect circle shape or an elliptical shape) or a polygonal shape (for example, a triangular shape or a square shape). Shape, pentagonal shape, hexagonal shape, etc.), and two or more of these shapes may be mixed.

  The average cell diameter of a foam is 40-1000 micrometers, for example, Preferably it is 80-600 micrometers, More preferably, it is about 100-500 micrometers. The average bubble diameter can be calculated by measurement using a conventional method, for example, a three-dimensional surface structure analysis microscope.

  The foam of the present invention is water-crosslinked, and the gel fraction measured by a method of extracting with xylene at 135 ° C. for 8 hours may be 30% by weight (particularly 50% by weight or more). It may be about -99 wt%, preferably 55-95 wt%, more preferably about 60-90 wt% (especially 65-80 wt%). If the gel fraction is too small, the surface smoothness and heat resistance of the foam may be reduced. In addition, in this invention, the measuring method of a gel fraction can be measured by the method as described in the Example mentioned later.

  The shape of the foam of the present invention is not particularly limited, and for example, a one-dimensional shape such as a rod shape or a string shape, a sheet shape, a film shape, a two-dimensional shape such as a two-dimensional mesh (net) shape, a block shape, It may be a three-dimensional shape such as a plate shape, a three-dimensional mesh shape, or a pipe shape.

  The thickness (average thickness) of a sheet-like foam can be suitably selected according to a use, for example, 0.5-50 mm, Preferably it is 0.7-30 mm, More preferably, about 1-20 mm may be sufficient.

  The surface of the foam of the present invention may be smooth or may have irregularities. For example, a sheet-like (or film-like) foam has a smooth sheet on both sides, an uneven surface (such as ribs) on one surface and a smooth surface on the other surface, and uneven surfaces (such as ribs) on both surfaces. The sheet | seat which has is included. In the present invention, since the bubble film can be thinned with a soft olefin polymer and a nucleating agent, the surface smoothness can also be improved.

[Method for producing foam]
The foam of the present invention is obtained by a production method including a foaming step of foam-molding the water-crosslinkable resin composition and a crosslinking step of crosslinking the foam-molded composition.

  In the present invention, the foaming step and the crosslinking step may proceed simultaneously. However, it is preferable that the foaming step and the crosslinking step be performed after the foaming step from the viewpoint that the foam molding can proceed smoothly and the expansion ratio can be improved.

  In the foaming step, as the foam molding method, a conventional method such as an extrusion molding method (for example, a T-die method, an inflation method, etc.), an injection molding method, or the like can be used. Of these, an extrusion method using a single screw or twin screw extruder is widely used. Further, if necessary, the foam (particularly, the sheet-like foam) is subjected to secondary processing [for example, thermoforming such as vacuum forming, pressure forming, vacuum pressure forming, match mold forming (for example, thermoforming using a mold). ] May be used. The foam molding or secondary molding temperature can be selected from the same range as the melt kneading temperature of the water-crosslinkable resin composition described above, but the melt kneaded composition is once cooled to a predetermined temperature and then extruded. May be. The temperature of extrusion molding after cooling (foaming temperature) can be selected according to the type of silylpoly-modified polyolefin, but may be 200 ° C. or lower in order to suppress the progress of crosslinking in the extruder, for example, 80 It is about -200 degreeC, Preferably it is 90-180 degreeC, More preferably, it is about 100-150 degreeC. If the foaming temperature is too low, the foaming ratio tends to decrease. If the foaming temperature is too high, crosslinking may proceed or the foaming ratio may decrease.

  In the foaming step, crosslinking may be performed as long as foaming of the silyl-modified polyolefin is not impaired, but it is preferable that the crosslinking is not substantially performed in order to ensure a high foaming ratio. In order to prevent water crosslinking from proceeding in the foaming step, for example, an additive that does not have a group capable of reacting with a hydrolytic condensable group is used, and the type of additive is selected. It is preferable to control in combination with adjusting the molding and adjusting the molding conditions.

  In the cross-linking step, the silyl-modified polyolefin can be cross-linked by water in the air. In the crosslinking treatment, crosslinking may be performed in an unheated state (room temperature of about 15 to 25 ° C.), but in order to improve productivity, crosslinking may be performed by heating. The heating temperature is, for example, about 40 to 100 ° C, preferably about 50 to 80 ° C, and more preferably about 55 to 70 ° C.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, the raw material (intermediate raw material) and evaluation method of a test piece are as follows.

[material]
(Polyolefin)
LDPE: Low density polyethylene, “Nobatech LD LE200M1” manufactured by Nippon Polyethylene Co., Ltd., MFR 0.8 g / 10 min EVA: Ethylene-vinyl acetate copolymer, “Ultrasen 543” manufactured by Tosoh Corporation, vinyl acetate content 10 mol %, MFR 1.3 g / 10 min.

(Additive)
Silyl compound: Trimethoxysilylethene, “KBM1003” manufactured by Shin-Etsu Chemical Co., Ltd.
Polymerization initiator (organic peroxide): Dicumyl peroxide, “Parkmill D-40” manufactured by NOF Corporation
Nucleating agent: Talc, “Microace K-1” manufactured by Nippon Talc Co., Ltd., average particle size 7.4 μm
Antioxidant: “Songwon 1010” manufactured by Songwon
Stearic acid amide (shrinkage preventive agent): NOF Corporation "Alflow S-10"
Crosslinking accelerator: Dioctyltin dilaurate, “KS-1200A-1” manufactured by Sakai Chemical Industry Co., Ltd.
Isobutane (foaming agent): Cosmo Oil and Gas Cosmo Isobutane Mix
Ethylenebis (tetrabromoisoindolinedione) (flame retardant): Albemarle Japan KK "BT-93"
Tetrabromophthalic anhydride (flame retardant): “RB-49” manufactured by Albemarle Japan
Ethane-diyl-bis-pentabromobenzene (flame retardant): “Daifunen EH931 (C)” manufactured by Dainichi Seika Kogyo Co., Ltd., containing antimony trioxide (antimony trioxide in the table is in Daifunen EH931 (C) Is antimony trioxide contained in
Decabromodiphenyl ether (flame retardant): “Frame Cut 110R” manufactured by Tosoh Corporation
Antimony trioxide (flame retardant aid): “Hiromaster C605” manufactured by Suzuhiro Chemical Co., Ltd.

[Intermediate raw materials]
(Synthesis example 1 of silyl-modified polyolefin)
0.4 parts by weight of a polymerization initiator, 0.5 parts by weight of a nucleating agent, 0.5 parts by weight of an antioxidant, 4.0 parts by weight of trimethoxysilylethene and 2.0 parts by weight of stearic acid amide are mixed, and 100 parts by weight of LDPE To the portion and mixed with a tumbler mixer. After mixing until the mixture containing the silyl compound adhered to the LDPE surface, the mixture was melt-kneaded at a pressure of 10 MPa using a single screw extruder having a barrel diameter of 180 ° C. to prepare silyl-modified polyolefin A.

(Synthesis example 2 of silyl-modified polyolefin B)
Silyl-modified polyolefin B was prepared in the same manner as in Synthesis Example 1 except that the amount of the polymerization initiator used was changed to 0.2 parts by weight and the amount of trimethoxysilylethene used was changed to 2.0 parts by weight.

(Synthesis example 3 of silyl-modified polyolefin C)
A silyl-modified polyolefin C was prepared in the same manner as in Synthesis Example 1 except that EVA was used instead of LDPE.

(Preparation of crosslinking accelerator masterbatch)
2.5 parts by weight of a crosslinking accelerator and 100 parts by weight of LDPE were mixed with a tumbler mixer. After mixing until the crosslinking accelerator adhered to the LDPE surface, the mixture was melt-kneaded at a pressure of 10 MPa using a single screw extruder having a barrel diameter of 180 ° C. to prepare a crosslinking accelerator master batch (MB).

  Table 1 shows the compositions of the silyl-modified polyolefin and the crosslinking accelerator MB.

[Apparent density]
The apparent density (g / cm ³ ) was measured according to JIS K6767.

[Foaming ratio]
The expansion ratio was calculated based on the following formula.

    Expansion ratio (times) = density of resin composition for foam / density of foam.

[Foaming]
The foamability was evaluated according to the following criteria based on the foaming ratio.

○… 20 times or more (pass)
X: Less than 20 times (failed).

[Gel fraction]
About 0.1 g (w1) of a sample is wrapped in a 400-mesh stainless wire mesh (w2) whose mass has been measured in advance, and extracted in 100 ml of xylene at 135 ° C. for 8 hours. Thereafter, the stainless steel wire mesh was taken out, dried at 80 ° C. for 4 hours, the mass (w3) was measured, and the gel fraction was calculated based on the following formula.

    Gel fraction (%) = {(w3-w2) / w1} × 100.

[Thickness shrinkage]
The thickness shrinkage rate was measured in accordance with JIS A9511 after treatment at 120 ° C. ± 5 ° C. for 168 hours.

[Heat-resistant]
The heat resistance was evaluated according to the following criteria based on the thickness shrinkage rate.

○… 7% or less (pass)
X: Exceeding 7% (failed).

[Burning distance and speed]
The burning distance and speed were measured according to UL94HBF method.

[Combustion quality]
The combustibility was evaluated according to the following criteria based on the combustion distance and speed.

○: Combustion distance is less than 125 mm or combustion speed is less than 40 mm / min (pass)
X: The combustion distance is 125 mm or more and the combustion speed is 40 mm / min or more (failed).

[Surface smoothness]
The surface appearance (surface smoothness) was evaluated by visually observing the surface of the foam and following criteria.

○: The surface is smooth ×: The surface is uneven.

[Comprehensive evaluation]
When all the evaluation items passed, the overall evaluation was “◯”, and when even one item failed, the overall evaluation was “x”.

Examples 1-7 and Comparative Examples 1-4
The components shown in Table 2 (excluding the foaming agent) were supplied to a first stage single screw extruder having a diameter of 40 mm, melt-kneaded at a temperature of 190 ° C. and a pressure of 17 MPa, and a foaming agent provided near the tip of the extruder. A foaming agent is press-kneaded into the resin composition from the inlet, cooled to a temperature of about 110 ° C. with a second stage single-screw extruder having a diameter of 50 mm, extruded into the atmosphere from a die, and pipe-shaped (outside A foam was obtained by extrusion molding to a diameter of 30 mm and an inner diameter of 20 mm. Furthermore, it was left to stand in an oven heated to about 60 ° C. for 1 day for water crosslinking with moisture in the oven. The evaluation results of the obtained foam are shown in Table 2.

  As apparent from Table 2, the foams of the examples were excellent in the balance of foamability, heat resistance, and surface smoothness, whereas the foams of Comparative Examples 1 to 4 had low foamability.

Examples 8-11
A foam was obtained in the same manner as in Example 1 at the ratio shown in Table 3. The evaluation results of the obtained foam are shown in Table 3.

  As is clear from the results in Table 3, the foams of the examples (particularly Examples 9 and 10) have a low burning rate.

  The water-crosslinkable resin composition of the present invention has a high expansion ratio and can form a foam excellent in heat resistance. Therefore, the resin composition and foam of the present invention can be used in various applications, for example, packaging materials for electric and electronic parts, heat insulating materials for piping, building materials (such as wall materials, gaps or joint fillers), and civil engineering. It can be used for materials, agricultural materials, automobile parts (interior materials such as automobile ceiling materials, exterior materials, etc.), packaging materials (containers, cushioning materials, etc.), daily life materials (daily necessities, etc.). The buffer material may be in various forms such as a sheet shape, a net shape, a jasper shape, a bag shape, a cap shape, a pipe shape, a block shape, and a rod shape.

Claims (16)

  A water-crosslinkable resin composition comprising a silyl-modified polyolefin and a flame retardant containing a halogen flame retardant having an acid anhydride group and / or an imide group.   The composition according to claim 1, wherein the halogen flame retardant comprises an aromatic ring or an aliphatic ring. The composition according to claim 1 or 2, wherein the halogen-based flame retardant is a halogenated phthalic anhydride and / or a C _1-10 alkylene bis-halogenated isoindolinedione.   The composition according to any one of claims 1 to 3, wherein the ratio of the flame retardant is 1 to 40 parts by weight with respect to 100 parts by weight of the silyl-modified polyolefin.   5. The composition according to claim 1, further comprising a flame retardant aid, wherein the weight ratio of the flame retardant to the flame retardant aid is the former / the latter = 85/15 to 45/55.   6. The composition according to claim 5, wherein the flame retardant aid is an antimony flame retardant aid.   Furthermore, the composition in any one of Claims 1-6 containing a volatile foaming agent.   Furthermore, the composition in any one of Claims 1-7 containing a fatty acid amide.   Furthermore, the composition in any one of Claims 1-8 containing a crosslinking accelerator.   The composition according to any one of claims 1 to 9, wherein the silyl-modified polyolefin is a polymer obtained by graft polymerization of a silyl compound having a hydrolytic condensable group and an ethylenically unsaturated bond to the polyolefin.   The composition according to any one of claims 1 to 10, which contains substantially no additive having a group capable of reacting with a hydrolytic condensable group.   The foam formed with the composition in any one of Claims 1-11.   The foam according to claim 12, wherein the gel fraction measured by a method of extracting with xylene at 135 ° C for 8 hours is 50% by weight or more.   The foam according to claim 12 or 13, wherein the foaming ratio is 10 times or more.   The manufacturing method of a foam including the foaming process of foam-molding the composition in any one of Claims 1-11, and the bridge | crosslinking process of bridge | crosslinking the foam-molded composition.   The method according to claim 15, wherein in the crosslinking step, the silyl-modified polyolefin is water-crosslinked with moisture in the air.