JP6667474B2 - Silane crosslinked resin molded article and method for producing the same, silane masterbatch, masterbatch mixture and molded article thereof, and heat-resistant product - Google Patents

Description

  The present invention relates to a silane cross-linked resin molded product and a method for producing the same, a silane master batch, a master batch mixture and a molded product thereof, and a heat-resistant product.

  Resin or rubber products such as coating materials for various industrial cables (including electric wires) and rubber mold materials (for example, glass run channels for automobiles, weather strips, rubber hoses, wiper blade rubber, and vibration-proof rubber) include heat resistance. Various characteristics are required.

Examples of the material of the resin or rubber product include a polyolefin resin.
Examples of the method for producing the resin or rubber product include injection molding, mold molding, and extrusion molding. Among them, extrusion molding is widely performed in the production of the resin or rubber product.
When extrusion molding is performed using a base resin containing a polyolefin-based resin, there is a problem that, with the elapse of molding time, resin scum (die scum) called "Mani" accumulates on a die portion of the extruder, thereby impairing extrudability. . Specifically, die scabs fall off from the dies and mix into the molded body, impairing the properties of the molded body, contacting the molded body during extrusion, impairing the appearance, and stopping the extruder to remove the die squash for a long time. For example, it is difficult to perform continuous molding over a long period of time.

  Patent Document 1 discloses a production method for reducing the occurrence of rust at the time of the extrusion molding, which includes a polyolefin-based resin, magnesium hydroxide surface-treated with a heavy polyorganosiloxane, and a methyl methacrylate polymer. A method for producing a molded article using a resin composition is described. Patent Document 3 proposes a method for manufacturing a flexible pipe made of a resin composition containing a chlorine-containing resin and an acrylic polymer resin. Patent Document 2 discloses a non-halogen flame retardant in which a metal hydrate, an acrylic processing aid and a fatty acid amide lubricant are added to a base resin composed of a crosslinked ethylene-vinyl acetate copolymer and a crystalline polyolefin. A production method using a resin composition has been proposed.

Further, in the above-mentioned molded product, a resin forming the product may be crosslinked in order to improve properties such as heat resistance. Examples of the method for crosslinking the resin include an electron beam crosslinking method and a chemical crosslinking method. Among the chemical cross-linking methods, the silane cross-linking method does not require special equipment in the cross-linking step, and is therefore more advantageous in production than other cross-linking methods.
The silane crosslinking method is a method in which a hydrolyzable silane coupling agent having an unsaturated group is grafted to a resin in the presence of an organic peroxide to obtain a silane graft resin, and then the silane grafting is performed in the presence of a silanol condensation catalyst. This is a method of cross-linking the resin by bringing the resin into contact with moisture.

JP 2006-8873 A JP 2011-195831 A JP 2015-166608 A

In the production methods described in Patent Literature 1 and Patent Literature 3, it is difficult to obtain a molded article having desired heat resistance because crosslinking is not performed.
Further, in the production method described in Patent Document 2, it is difficult to obtain a molded body having a desired heat resistance because the network formation in the base resin is insufficient.
Further, the molded product obtained by the conventional silane cross-linking method has insufficient cross-linking, and has room for improvement in heat resistance. Further, at the time of molding, a bump-like substance (also referred to as a gel spot or a bump) is easily generated on the surface of the molded article, and there is a problem in the appearance of the molded article.

An object of the present invention is to provide a silane cross-linked resin molded article which can overcome the above-mentioned problems, can be produced with reduced generation of resin (resin scum) during molding, has excellent appearance, and has desired heat resistance, and a method for producing the same. Make it an issue.
Another object of the present invention is to provide a silane masterbatch, a masterbatch mixture, and a molded article thereof, which can form the silane crosslinked resin molded article.
A further object of the present invention is to provide a heat-resistant product containing the above-mentioned silane crosslinked resin molded article.

  The present inventors, in the silane crosslinking method, a mixture containing an acrylic polymer, an organic peroxide, an inorganic filler and a silane coupling agent in a specific ratio with respect to a polyolefin-based resin or rubber, an organic peroxide. Melt-kneading at or above the decomposition temperature of the mixture, mixing the obtained composition with a silanol condensation catalyst, by a specific manufacturing method including a molding step, can reduce the occurrence of rust during molding, excellent heat resistance and appearance It has been found that a silane crosslinked resin molded article can be produced. The present inventors have further studied based on this finding, and have accomplished the present invention.

That is, the object of the present invention has been achieved by the following means.
[1] A polyolefin- based base rubber containing ethylene-α-olefin copolymer rubber or containing ethylene-α-olefin copolymer rubber and styrene-based thermoplastic elastomer (provided that ethylene-vinyl acetate copolymer rubber is used) With respect to 100 parts by mass, an acrylic polymer 0.1 to 20 parts by mass, an organic peroxide 0.003 to 0.3 parts by mass, and an inorganic filler 0.5 to 400 parts by mass, More than 2 parts by mass and not more than 15.0 parts by mass of the silane coupling agent is melt-mixed at a temperature not lower than the decomposition temperature of the organic peroxide , and a graft reaction is caused between the polyolefin-based base rubber and the silane coupling agent. (A) preparing a silane masterbatch containing the silane crosslinkable resin by
(B) shaping after mixing the silane master batch obtained in the step (a) and the silanol condensation catalyst;
A step (c) of bringing the molded body obtained in the step (b) into contact with moisture to crosslink,
A method for producing a silane crosslinked resin molded article having:
[2] The method for producing a silane crosslinked resin molded product according to [1], wherein the acrylic polymer has a mass average molecular weight of 100,000 to 1,000,000.
[3] The method for producing a silane-crosslinked resin molded article according to [1] or [2], wherein the acrylic polymer is 0.5 to 10 parts by mass based on 100 parts by mass of the polyolefin- based base rubber .
[4] The production of the silane crosslinked resin molded article according to any one of [1] to [3], wherein the acrylic polymer is 1 to 6 parts by mass with respect to 100 parts by mass of the polyolefin- based base rubber. Method.
[5] The method for producing a silane crosslinked resin molded article according to any one of [1] to [4], wherein the silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane.
[6] The inorganic filler according to any one of [1] to [5], wherein the inorganic filler is at least one selected from the group consisting of silica, boehmite, clay, talc, aluminum hydroxide, magnesium hydroxide, and calcium carbonate. The method for producing a silane crosslinked resin molded article according to the above.
[7] The method for producing a silane crosslinked resin molded product according to any one of [1] to [6], wherein the melt mixing in the step (a) is performed using a closed mixer.
[8] A polyolefin- based base rubber containing ethylene-α-olefin copolymer rubber or containing ethylene-α-olefin copolymer rubber and styrene-based thermoplastic elastomer (provided that ethylene-vinyl acetate copolymer rubber is used) against the excluded) 100 parts by weight polymer, acrylic polymer 0.1-20 parts by weight, and an organic peroxide 0.003 to 0.3 parts by weight of an inorganic filler 0.5 to 400 parts by weight, silane A silane masterbatch used for producing a masterbatch mixture obtained by mixing a coupling agent in an amount of more than 2 parts by mass and not more than 15.0 parts by mass with a silanol condensation catalyst,
The base rubber, the acrylic polymer, the organic peroxide, the inorganic filler, and the silane coupling agent are melt-mixed at a temperature equal to or higher than the decomposition temperature of the organic peroxide, and the polyolefin-based rubber and the silane are mixed. A silane masterbatch containing a silane crosslinkable resin obtained by performing a graft reaction with a coupling agent .
[9] A master batch mixture containing the silane master batch according to [8] and a silanol condensation catalyst.
[10] A molded article formed by dry-blending the silane masterbatch according to [9] and a silanol condensation catalyst.
[11] A silane-crosslinked resin molded article produced by the method for producing a silane-crosslinked resin molded article according to any one of [1] to [7].
[12] The silane-crosslinked resin molded product according to [11], wherein the base rubber is crosslinked with the inorganic filler via a silanol bond.
[13] A heat-resistant product comprising the silane crosslinked resin molded product according to [11] or [12].

  In this specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit and an upper limit.

According to the present invention, it is possible to manufacture a silane cross-linked resin molded article having excellent heat resistance and appearance, which overcomes the above-mentioned problems and reduces the occurrence of mold buildup during molding.
Therefore, according to the present invention, it is possible to provide a silane crosslinked resin molded article having excellent heat resistance and appearance and a method for producing the same. In addition, it is possible to provide a silane masterbatch, a masterbatch mixture, and a molded article thereof, which can form a silane crosslinked resin molded article exhibiting such excellent characteristics. Further, it is possible to provide a heat-resistant product including a silane cross-linked resin molded product exhibiting excellent characteristics.

Hereinafter, preferred embodiments of the present invention will be described.
First, each component used in the present invention will be described.

<Polyolefin-based resin or rubber>
The polyolefin-based base resin or rubber (hereinafter, also referred to as a base resin) contains a polyolefin-based resin or rubber. The polyolefin resin or rubber is not particularly limited, and for example, the following can be used.
Further, the base resin may contain a styrene-based thermoplastic elastomer and a mineral oil in addition to the polyolefin-based resin or rubber.

(A1) Resin of ethylene-α-olefin copolymer Examples of the ethylene-α-olefin copolymer include a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms. Although it does not specifically limit as an alpha-olefin, 1-propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, etc. are mentioned.
Here, the ethylene-α-olefin copolymer has an ethylene component content of about 80 to 99% by mass.
Examples of the ethylene-α-olefin copolymer include LDPE (low-density polyethylene), LLDPE (linear low-density polyethylene), MDPE (medium-density polyethylene), and polyethylene resins synthesized in the presence of a metallocene catalyst. Among them, LLDPE synthesized in the presence of a metallocene catalyst is preferable.
The density of the ethylene -α- olefin copolymer is preferably ^{0.880~0.940g / cm 3, 0.900~0.930g / cm} 3 is more preferable. When the density is 0.880 to 0.940 g / cm ³ , excellent mechanical properties can be obtained. Further, when the base resin contains a mineral oil, the mineral oil hardly bleeds out and can maintain the appearance of the molded article for a long period of time. The density of the ethylene-α-olefin copolymer can be measured by the method described in JIS K7112.
Examples of the ethylene-α-olefin copolymer include “Kernel” (trade name, manufactured by Nippon Polyethylene), “Evolu” (trade name, manufactured by Prime Polymer), and “Sumikasen” (trade name, manufactured by Sumitomo Chemical Co., Ltd.) , "Engage" (trade name, manufactured by Dow) and the like.
The ethylene-α-olefin copolymer resin contained in the base resin may be one type or two or more types.

(A2) Ethylene-α-olefin copolymer rubber The ethylene-α-olefin copolymer rubber is not particularly limited as long as it is a rubber composed of a copolymer of ethylene and the α-olefin. For example, it is an ethylene-propylene copolymer rubber (EP rubber (EPM)), and includes a rubber-like copolymer of ethylene and propylene. Here, the ethylene-propylene copolymer rubber refers to a rubber having an ethylene component content of usually about 40 to 75% by mass. The ethylene component content in the ethylene-propylene copolymer rubber is preferably from 50 to 75% by mass, and more preferably from 55 to 70% by mass. The ethylene component content is a value measured according to the method described in ASTM D3900.

Ethylene-α-olefin copolymer rubber is an ethylene-propylene terpolymer having a repeating unit having an unsaturated group as a third component other than ethylene and α-olefin (propylene) (for example, ethylene, α-olefin, diene and Terpolymers (EPDM)). In the present invention, one or both of EPM and EPDM may be used as the ethylene-α-olefin copolymer rubber.
Examples of the ethylene-propylene copolymer rubber include "Mitsui EPT" (trade name, manufactured by Mitsui Chemicals, Inc.) and "Nodel" (trade name, manufactured by Dow Chemical Co., Ltd.).
The ethylene-α-olefin copolymer rubber contained in the base resin may be one type or two or more types.

(A3) Ethylene-based copolymer other than ethylene-α-olefin copolymer Ethylene-based copolymer other than ethylene-α-olefin copolymer includes ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic An acid ester copolymer, an ethylene- (meth) acrylic acid copolymer, or the like can be used alone or in an appropriate mixture. By using these ethylene copolymers, flame retardancy can be improved and flexibility can be imparted.
As the ethylene-based copolymer other than the ethylene-α-olefin copolymer, an ethylene-vinyl acetate copolymer and / or an ethylene- (meth) acrylate copolymer can be preferably used.

The ethylene-vinyl acetate copolymer may be an alternating copolymer obtained by alternately polymerizing an ethylene component and a vinyl acetate component as long as it is a copolymer of ethylene and vinyl acetate. It may be a block copolymer in which a polymerization block and a polymerization block of a vinyl acetate component are bonded, or may be a random copolymer in which an ethylene component and a vinyl acetate component are randomly polymerized.
As the ethylene-vinyl acetate copolymer, those having a vinyl acetate component content of 10 to 80% by mass are preferably used. The content of the vinyl acetate component in the ethylene-vinyl acetate copolymer is preferably 12 to 70% by mass, more preferably 15 to 50% by mass, and still more preferably 17 to 45% by mass. Two or more resins having different contents of the vinyl acetate component may be combined.
Examples of the ethylene-vinyl acetate copolymer include Evaflex (trade name, manufactured by Du Pont-Mitsui Polychemicals) and Levaprene (trade name, manufactured by Bayer AG).

The ethylene- (meth) acrylate copolymer includes both an ethylene-acrylate copolymer and an ethylene-methacrylate copolymer. In the present specification, the term “ethylene- (meth) acrylate copolymer” includes both ethylene-methacrylate copolymer and ethylene-methacrylate ester copolymer. (Meth) acrylate copolymer ".
As long as the ethylene- (meth) acrylate copolymer is a copolymer of ethylene and (meth) acrylate, as in the above-mentioned ethylene-vinyl acetate copolymer, the alternating copolymer and the block copolymer are used. Any of a polymer and a random copolymer may be used. The (meth) acrylate component is not particularly limited, but preferably has an alkyl group having 1 to 4 carbon atoms, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, and butyl acrylate. Is mentioned.

  The content of the (meth) acrylate component, which is a copolymer component of the ethylene- (meth) acrylate copolymer, is preferably from 10 to 40% by mass. When the content is in the above range, high tensile strength can be maintained and flame retardancy can be imparted.

Examples of the ethylene- (meth) acrylate copolymer include ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, and ethylene-ethyl methacrylate copolymer. Coalescence and the like.
Examples of the ethylene-acrylate copolymer include Elvaloy (trade name, manufactured by Du Pont-Mitsui Polychemicals).

Examples of the ethylene- (meth) acrylic acid copolymer include Nucrel (trade name, manufactured by Du Pont-Mitsui Polychemicals).
The ethylene-based copolymer other than the ethylene-α-olefin copolymer contained in the base resin may be one type or two or more types.

(A4) High-density polyethylene resin As the high-density polyethylene resin (HDPE), a polyethylene homopolymer or the like can be used.
Is not particularly limited density, preferably 0.965 g / cm ³ or less exceed 0.940, 0.945~0.960g / cm ³ is more preferable. The density of the high-density polyethylene resin can be measured by the method described in JIS K7112.
The MFR (190 ° C., 2.16 kg) is also not particularly limited, but is preferably from 0.2 to 10 g / 10 min, more preferably from 0.8 to 5 g / 10 min. If it is too small, the motor load of the manufacturing equipment will increase, and the high-speed moldability may be poor.
Examples of the high-density polyethylene resin include “HIZEX” (trade name, manufactured by Prime Polymer Co., Ltd.), “Nipolon Hard” (trade name, manufactured by Tosoh Corporation), and “Novatech” (trade name, manufactured by Nippon Polyethylene Corporation). it can.
The high-density polyethylene resin contained in the base resin may be one type or two or more types.

(A5) Polypropylene resin As the polypropylene resin, resins such as propylene homopolymer (homopolypropylene resin), ethylene-propylene random copolymer, and ethylene-propylene block copolymer can be used.
Here, the ethylene-propylene random copolymer refers to one having an ethylene component content of about 1 to 10% by mass, and refers to one in which the ethylene component is randomly incorporated into a propylene chain. The ethylene-propylene block copolymer has a total content of an ethylene component and an ethylene-propylene rubber (EPR) component of about 5 to 20% by mass. The ethylene component and the EPR component are independently contained in the propylene component. It is an existing sea-island structure. Particularly preferred is an ethylene-propylene random copolymer from the viewpoint of the appearance of a molded article after extrusion.
The MFR (JIS K 7210, 230 ° C., 2.16 kg) of the polypropylene resin is preferably 0.5 to 50 g / 10 min, more preferably 0.5 to 30 g / 10 min, and still more preferably 0.5 to 10 g. / 10 minutes. By blending a polypropylene resin having such an MFR value, the molecular weight distribution of the base resin component can be broadened, and the appearance of a molded article after extrusion molding can be improved.
One type of polypropylene may be used, or two or more types may be used in combination.
Examples of the polypropylene resin include “San Allomer PP” (trade name, manufactured by Sun Allomer Co.), “Prime Polypro” (trade name, manufactured by Prime Polymer Co.), “Novatech PP” (trade name, manufactured by Nippon Polypropylene Co., Ltd.), and the like. The base resin may contain one or more polypropylene resins.

In the base resin, the content of each component is appropriately determined such that the total of each component such as the polyolefin-based resin or rubber, a styrene-based thermoplastic elastomer and a mineral oil described below is 100% by mass, and preferably, It is selected from the following range.
When the base resin contains an ethylene-α-olefin copolymer resin, the content of the ethylene-α-olefin copolymer resin in the base resin is preferably 20 to 100% by mass, and 30 to 80% by mass. % Is more preferred.

(A6) Styrene-based thermoplastic elastomer The styrene-based thermoplastic elastomer is a block copolymer or random copolymer elastomer of a component derived from an aromatic vinyl compound and a conjugated diene compound, or a hydrogenated product thereof. And so on. The styrene-based thermoplastic elastomer preferably contains an aromatic vinyl compound in an amount of 5 to 70% by mass, more preferably 10 to 60% by mass. This content can be determined by measuring the UV absorption spectrum with an ultraviolet spectrophotometer using a chloroform solution, for example.
As the aromatic vinyl compound, for example, one or more of styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene and the like can be selected, and among them, styrene is preferable. As the conjugated diene compound, for example, one or more kinds are selected from butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene and the like, and among them, butadiene, isoprene and these Combinations are preferred.

As the styrene-based thermoplastic elastomer, SBS (styrene-butadiene-styrene block copolymer), SIS (styrene-isoprene-styrene block copolymer), SEBS (styrene-ethylene-butylene-styrene block copolymer: hydrogenated SBS), SEEPS ( Styrene-ethylene-ethylene-propylene-styrene block copolymer), SEPS (styrene-ethylene-propylene-styrene block copolymer: hydrogenated SIS), HSBR (hydrogenated styrene-butadiene random copolymer), and the like.
As the styrene-based thermoplastic elastomer, a binary or ternary copolymer composed of a polystyrene block and an elastomer block having a polyolefin structure can be used.
Examples of the styrene-based thermoplastic elastomer include “Septon” (trade name, manufactured by Kuraray Co., Ltd.), “TUFTEC” (trade name, manufactured by Asahi Kasei Chemicals Co., Ltd.), and “Dynalon” (trade name, manufactured by JSR Corporation). it can.

  The styrenic thermoplastic elastomer contained in the base resin may be one type or two or more types.

  The content of the styrene-based thermoplastic elastomer is preferably from 10 to 40% by mass based on 100% by mass of the base resin. When the content is in the range of 10 to 40% by mass, flexibility can be imparted, and gel spots are particularly unlikely to occur.

(A7) Mineral oil The mineral oil used in the present invention is a mixed oil containing an oil having an aromatic ring, an oil having a naphthene ring, and an oil having a paraffin chain. A paraffinic oil is one in which the number of carbon atoms (CP) of a paraffin chain is, for example, 50% or more and less than 75% of the total number of carbon atoms of an aromatic ring, a naphthene ring, and a paraffin chain, and the number of carbon atoms (CN) of a naphthenic chain is 20 to less than 40%, wherein the aromatic ring (CA) has a carbon number of 3 to less than 10%. Naphthenic oils are those having 40 to less than 60% of CN, 30% to less than 50% of CP, and 8% to less than 16% of CA with respect to the total carbon number. Means 16% or more.
The mineral oil is preferably a paraffinic oil or a naphthenic oil, and more preferably a paraffinic oil in terms of mechanical strength.
The mineral oil preferably has a dynamic viscosity at 40 ° C of ²⁰ to 500 mm ² / s, a pour point of -10 to -15 ° C, and a flash point (COC) of 180 to 300 ° C.
The content of the mineral oil is preferably from 10 to 40% by mass based on 100% by mass of the base resin. When the content is in the range of 10 to 40% by mass, gel spots are hardly generated at the time of molding and bleed out is hard to occur. Therefore, a molded article having excellent appearance can be obtained.
The mineral oil includes, for example, "Diana Process Oil" (trade name, manufactured by Idemitsu Kosan Co., Ltd.) and "Cosmo Neutral" (trade name, manufactured by Cosmo Oil Lubricant Co., Ltd.).

  From the viewpoint of obtaining a molded article having an excellent appearance, the base resin preferably contains an ethylene-α-olefin copolymer rubber, a styrene-based thermoplastic elastomer, and a mineral oil.

<Acrylic polymer>
As the acrylic polymer, a homopolymer or copolymer containing (meth) acrylic acid or (meth) acrylic acid ester as a component, that is, a (meth) acrylic acid polymer, a (meth) acrylic acid ester polymer, There is no particular limitation as long as it is a copolymer of (meth) acrylic acid and (meth) acrylic acid ester. As the acrylic processing aid, those used in the production of a resin molded product can be used.
As the (meth) acrylate, alkyl (meth) acrylate is preferred. The alkyl group of the alkyl (meth) acrylate preferably has 1 to 12 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. Specific examples of the alkyl (meth) acrylate preferably include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and ethyl methacrylate. These can be used alone or in combination.
The mass average molecular weight of the acrylic polymer is not particularly limited, but is preferably 50,000 to 3.5 million, more preferably 100,000 to 1,000,000, and further preferably 100,000 to 500,000. From the viewpoint of reducing bleed-out and maintaining the appearance of the molded article for a long period of time, it is preferable that the weight average molecular weight is higher.
Here, the mass average molecular weight can be measured by, for example, GPC (Gel Permeation Chromatography) using THF (tetrahydrofuran) as a developing solvent. Specifically, a calibration curve was prepared for the relationship between the peak position of the GPC spectrogram and the molecular weight of known polystyrene, and then the spectrogram of the acrylic polymer measured by GPC was compared with the calibration curve of polystyrene of known molecular weight. It is determined by calculating the polystyrene equivalent mass average molecular weight.
Examples of the acrylic polymer include Metablen L-1000 (trade name, manufactured by Mitsubishi Rayon Co., Ltd.).

  By using the acrylic polymer, lubricity is imparted to the surface of the molded body, friction between the molded body and a die of an extruder is reduced, and the scumming can be suppressed. In addition, since the acrylic polymer has high compatibility with the polyolefin-based resin or rubber, it helps to disperse various additives such as a silane coupling agent and an inorganic filler to obtain a molded article having good physical properties. Can be. In addition, when an acrylic polymer is used, the graft reaction is not inhibited or excessively promoted during the silane master batch production process, and the condensation reaction between silanol groups is suppressed. As a result, without impairing the physical properties such as heat resistance, it is possible to suppress the build-up during extrusion and to obtain a molded article with a beautiful appearance.

<Organic peroxide>
The organic peroxide generates a radical at least by thermal decomposition, and functions as a catalyst to cause a graft reaction by a radical reaction of the silane coupling agent to the resin component. In particular, when the reaction site of the silane coupling agent contains, for example, an ethylenically unsaturated group, a graft reaction occurs by a radical reaction between the ethylenically unsaturated group and the resin component (including a reaction for extracting hydrogen radicals from the resin component). Work to make it work.
The organic peroxide is not particularly limited as long as it generates a radical. For example, general formulas: R ¹ -OO-R ² , R ³ -OO-C (＝ O) R ⁴ , R ⁵ C A compound represented by (＝ O) —OO (C ＝ O) R ⁶ is preferable. Here, R ^{1 to} R ⁶ each independently represent an alkyl group, an aryl group or an acyl group. Of R ^{1 to} R ⁶ of each compound, those in which all are alkyl groups, or those in which any one is an alkyl group and the rest are acyl groups, are preferred.

  Such organic peroxides include, for example, dicumyl peroxide (DCP), di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, , 5-Dimethyl-2,5-di (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3 , 3,5-trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxide Oxybenzoate, tert-butyl peroxyisopropyl carbonate, diacetate Peroxide, lauroyl peroxide, it may be mentioned tert- butyl cumyl peroxide and the like. Among them, dicumyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, and 2,5-dimethyl-2 are preferable in terms of odor, coloring, and scorch stability. , 5-Di- (tert-butylperoxy) hexyne-3 is preferred.

The decomposition temperature of the organic peroxide is preferably from 80 to 195 ° C, particularly preferably from 125 to 180 ° C.
In the present invention, the decomposition temperature of an organic peroxide is a temperature at which, when an organic peroxide having a single composition is heated, a decomposition reaction by itself occurs in two or more kinds of compounds at a certain temperature or temperature range. means. Specifically, it refers to a temperature at which heat absorption or heat generation starts when heated from room temperature at a rate of 5 ° C./min in a nitrogen gas atmosphere by a thermal analysis such as a DSC method.

<Inorganic filler>
In the present invention, the inorganic filler is not particularly limited as long as the surface has a site capable of chemically bonding to a reaction site such as a silanol group of a silane coupling agent with a hydrogen bond or a covalent bond, or an intermolecular bond on its surface. It can be used without. Examples of the part of the inorganic filler that can chemically bond with the reaction part of the silane coupling agent include an OH group (OH group such as a hydroxyl group, a water molecule containing water or water of crystallization, an OH group such as a carboxy group), an amino group, and an SH group. Can be

  The inorganic filler is not particularly limited, and includes, for example, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide (boehmite, etc.), aluminum nitride, Metal hydrates such as aluminum borate whiskers, hydrated aluminum silicate, hydrated magnesium silicate, basic magnesium carbonate, hydrotalcite, talc, and other compounds having a hydroxyl group or crystal water. In addition, boron nitride, silica (crystalline silica, amorphous silica, etc.), carbon, clay, zinc oxide, tin oxide, titanium oxide, molybdenum oxide, antimony trioxide, silicone compounds, quartz, zinc borate, white carbon, Zinc borate, zinc hydroxy stannate, zinc stannate and the like can be mentioned.

As the inorganic filler, a surface-treated inorganic filler surface-treated with a silane coupling agent or the like can be used. For example, as the silane coupling agent surface-treated inorganic filler, Kisuma 5L and Kisuma 5P (both are trade names, magnesium hydroxide, manufactured by Kyowa Chemical Industry Co., Ltd.) and the like are exemplified. Although the surface treatment amount of the inorganic filler with the silane coupling agent is not particularly limited, it is, for example, 3% by mass or less.
Among these inorganic fillers, silica, boehmite, clay, talc, aluminum hydroxide, magnesium hydroxide or calcium carbonate or a combination thereof is preferred.
One type of inorganic filler may be used alone, or two or more types may be used in combination.

  When the inorganic filler is a powder, the average particle size of the inorganic filler is preferably from 0.2 to 10 μm, more preferably from 0.3 to 8 μm, still more preferably from 0.4 to 5 μm, particularly preferably from 0.4 to 3 μm. preferable. When the average particle size is within the above range, the effect of holding the silane coupling agent is high and the heat resistance is excellent. In addition, the inorganic filler does not easily undergo secondary agglomeration when mixed with the silane coupling agent, resulting in an excellent appearance. The average particle size is obtained by dispersing an inorganic filler in alcohol or water, and using an optical particle size measuring device such as a laser diffraction / scattering type particle size distribution measuring device.

<Silane coupling agent>
The silane coupling agent used in the present invention can chemically bond a graft reaction site (group or atom) capable of performing a graft reaction to a base resin in the presence of a radical generated by decomposition of an organic peroxide with an inorganic filler. Any site may be used as long as it has at least a reaction site capable of reacting with a site and capable of silanol condensation (including a site generated by hydrolysis, such as a silyl ester group). Examples of such a silane coupling agent include silane coupling agents conventionally used in a silane crosslinking method.

  As the silane coupling agent, for example, a compound represented by the following general formula (1) can be used.

In the general formula (1), R _a11 is a group containing an ethylenically unsaturated group, and R _b11 is an aliphatic hydrocarbon group, a hydrogen atom, or Y ¹³ . Y ¹¹ , Y ¹² and Y ¹³ are hydrolyzable organic groups. Y ¹¹ , Y ¹² and Y ¹³ may be the same or different.
_Ra11 is a grafting reaction site, and is preferably a group containing an ethylenically unsaturated group. Examples of the group containing an ethylenically unsaturated group include a vinyl group, a (meth) acryloyloxyalkylene group, and a p-styryl group. Among them, a vinyl group is preferable.

R _b11 represents an aliphatic hydrocarbon group, a hydrogen atom or Y ¹³ described later. Examples of the aliphatic hydrocarbon group include a monovalent aliphatic hydrocarbon group having 1 to 8 carbon atoms excluding an aliphatic unsaturated hydrocarbon group. R _b11 is preferably below ^{Y 13.}

Y ¹¹ , Y ¹² and Y ¹³ represent a reactive site capable of silanol condensation (hydrolyzable organic group). Examples thereof include an alkoxy group having 1 to 6 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, and an acyloxy group having 1 to 4 carbon atoms, and an alkoxy group is preferable. Specific examples of the hydrolyzable organic group include methoxy, ethoxy, butoxy, acyloxy and the like. Among them, methoxy or ethoxy is more preferable from the viewpoint of the reactivity of the silane coupling agent.

The silane coupling agent is preferably a silane coupling agent having a high hydrolysis rate, and more preferably a silane coupling agent in which R _b11 is Y ¹³ and Y ¹¹ , Y ¹² and Y ¹³ are the same as each other. A ring agent or a silane coupling agent in which at least one of Y ¹¹ , Y ¹² and Y ¹³ is a methoxy group.

Specific examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinyldimethoxyethoxysilane, vinyldimethoxybutoxysilane, vinyldiethoxybutoxysilane, allyltrimethoxysilane, and allyltrimethoxysilane. Examples thereof include vinyl silanes such as ethoxy silane and vinyl triacetoxy silane, and (meth) acryloxy silanes such as methacryloxy propyl trimethoxy silane, methacryloxy propyl triethoxy silane, and methacryloxy propyl methyl dimethoxy silane.
Among the above silane coupling agents, a silane coupling agent having a vinyl group and an alkoxy group at a terminal is more preferable, and vinyltrimethoxysilane or vinyltriethoxysilane is particularly preferable.
One type of silane coupling agent may be used alone, or two or more types may be used in combination. Further, it may be used as it is, or may be used after diluted with a solvent or the like.

<Silanol condensation catalyst>
The silanol condensation catalyst has a function to cause a silane coupling agent grafted to a polyolefin resin or rubber to undergo a condensation reaction in the presence of moisture. Based on the function of the silanol condensation catalyst, the resin components are cross-linked via the silane coupling agent. As a result, a silane crosslinked resin molded article having excellent heat resistance can be obtained.

The silanol condensation catalyst is not particularly restricted but includes, for example, organotin compounds, metallic soaps, platinum compounds and the like. Typical silanol condensation catalysts include, for example, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctate, dibutyltin diacetate, zinc stearate, lead stearate, barium stearate, calcium stearate, sodium stearate, lead naphthenate, Lead sulfate, zinc sulfate, organic platinum compounds and the like are used.
When the silane graft resin component and the silane crosslinking catalyst masterbatch are mixed, the addition amount of the silanol condensation catalyst is 0.02 to 0.5 part by mass, preferably 0.1 to 0.5 part by mass, based on 100 parts by mass of both resin components. The amount is from 0.5 to 0.4 part by mass, and more preferably from 0.08 to 0.3 part by mass. By adjusting to this blending amount, generation of gel spots during molding can be suppressed, and crosslinking is sufficiently advanced, resulting in excellent strength and heat resistance.

<Carrier resin>
The silanol condensation catalyst is used by being mixed with a resin if desired. Such a resin (also referred to as a carrier resin) is not particularly limited, but each resin or rubber described for the base resin can be used.

<Other additives>
In the present invention, various additives commonly used in electric wires, electric cables, electric cords, automobile members, OA equipment, building members, miscellaneous goods, sheets, foams, tubes, and pipes are intended. You may mix suitably as long as the effect is not impaired. Examples of such additives include a crosslinking aid, an antioxidant, a lubricant, a metal deactivator, a flame retardant (auxiliary) agent, and other resins.
The crosslinking assistant refers to a compound that forms a partially crosslinked structure with a resin component in the presence of an organic peroxide. For example, a polyfunctional compound and the like can be mentioned.
Although it does not specifically limit as an antioxidant, For example, an amine antioxidant, a phenol antioxidant, a sulfur antioxidant, etc. are mentioned.
Examples of the lubricant include lubricants such as hydrocarbon, siloxane, fatty acid, fatty acid amide, ester, alcohol, and metallic soap.

Next, the production method of the present invention will be specifically described.
The method for producing a silane crosslinked resin molded article of the present invention includes the following steps (a) to (c).
The silane master batch of the present invention is produced by the following step (a), and the master batch mixture of the present invention is produced by the following steps (a) and (b).

Step (a): 0.1 to 20 parts by mass of an acrylic polymer, 0.003 to 0.3 parts by mass of an organic peroxide, and 0. 0 parts by mass of an inorganic filler with respect to 100 parts by mass of a polyolefin-based resin or rubber. 5 to 400 parts by mass and more than 2 parts by mass and 15.0 parts by mass or less of the silane coupling agent are melt-mixed (also referred to as melt-kneading or kneading) at a temperature not lower than the decomposition temperature of the organic peroxide, Step of preparing a silane masterbatch Step (b): a step of mixing the silane masterbatch obtained in the step (a) with a silanol condensation catalyst and then molding Step (c): a molded article obtained in the step (b) Here, mixing is referred to as obtaining a uniform mixture.

  In the step (a), the base resin component is not particularly limited as long as it contains a polyolefin-based resin or rubber, and a styrene-based thermoplastic elastomer, a mineral oil, or the like can be used together.

  In step (a), the base resin is melt-mixed with an acrylic polymer, an inorganic filler and a silane coupling agent at a temperature equal to or higher than the decomposition temperature of the organic peroxide in the presence of the organic peroxide. By the step (a), a silane masterbatch (also referred to as silane MB) is obtained as a molten mixture.

  In the step (a), the blending amount of the acrylic polymer is 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 1 to 6 parts by mass with respect to 100 parts by mass of the base resin. More preferred. If the blending amount of the acrylic polymer is less than 0.1 part by mass, scumming may occur during extrusion molding. On the other hand, if it exceeds 20 parts by mass, physical properties such as heat resistance and mechanical strength may be reduced. Bleed out may occur.

  In the step (a), the compounding amount of the organic peroxide is 0.003 to 0.3 parts by mass, preferably 0.005 to 0.3 parts by mass, and more preferably 0.005 to 0.3 parts by mass with respect to 100 parts by mass of the base resin. 005 to 0.1 part by mass is more preferred. If the amount of the organic peroxide is less than 0.003 parts by mass, the graft reaction does not proceed, the unreacted silane coupling agents are condensed or the unreacted silane coupling agent volatilizes, and the heat resistance is sufficiently increased. May not be available. On the other hand, if it exceeds 0.3 parts by mass, many of the resin components are directly crosslinked by side reactions to form bumps, which may cause poor appearance. In addition, a silane master batch having excellent extrudability may not be obtained. That is, by setting the compounding amount of the organic peroxide within this range, a graft reaction can be performed within an appropriate range, and a silane master excellent in extrudability without generating gel-like bumps (agglomerates). Batches and the like can be obtained.

  The compounding amount of the inorganic filler is 0.5 to 400 parts by mass, preferably 30 to 280 parts by mass, based on 100 parts by mass of the base resin. If the compounding amount of the inorganic filler is less than 0.5 part by mass, the graft reaction of the silane coupling agent becomes non-uniform, and excellent heat resistance may not be imparted to the silane cross-linked resin molded article. Further, the graft reaction of the silane coupling agent becomes non-uniform, and the appearance of the silane cross-linked resin molded article may be deteriorated. On the other hand, when the amount exceeds 400 parts by mass, the load during molding or melt mixing becomes extremely large, and secondary molding may be difficult. In addition, heat resistance and appearance may be reduced.

The amount of the silane coupling agent is more than 2.0 parts by mass and 15.0 parts by mass or less based on 100 parts by mass of the base resin. If the compounding amount of the silane coupling agent is 2.0 parts by mass or less, the crosslinking reaction does not sufficiently proceed, and excellent heat resistance may not be exhibited. In addition, when molded together with the silanol condensation catalyst, poor appearance or lumps may occur, and when the extruder is stopped, many lumps may occur. On the other hand, if the amount exceeds 15.0 parts by mass, the silane coupling agent cannot be completely adsorbed on the surface of the inorganic filler, and the silane coupling agent volatilizes during the melt mixing, which is not economical. In addition, the silane coupling agent that does not adsorb may be condensed, and the molded article may have crosslinked gel spots or burns, which may deteriorate the appearance.
From the above viewpoint, the compounding amount of the silane coupling agent is preferably 3 to 12.0 parts by mass, more preferably 4 to 12.0 parts by mass, based on 100 parts by mass of the base resin.

  The amount of the silanol condensation catalyst is not particularly limited, and is preferably 0.0001 to 0.5 part by mass, more preferably 0.001 to 0.2 part by mass, based on 100 parts by mass of the base resin. When the amount of the silanol condensation catalyst is within the above range, the crosslinking reaction by the condensation reaction of the silane coupling agent tends to proceed almost uniformly, and the heat resistance, appearance and physical properties of the silane crosslinked resin molded article are excellent, and the productivity is also high. improves. That is, if the blending amount of the silanol condensation catalyst is too small, the crosslinking by the condensation reaction of the silane coupling agent becomes difficult to proceed, and the heat resistance of the silane crosslinked resin molded body is not easily improved, and the productivity is reduced, or the crosslinking is reduced. May be uneven. On the other hand, if the content is too large, the silanol condensation reaction proceeds very quickly, and partial gelation may occur, which may lower the appearance. In addition, the physical properties of the silane cross-linked resin molded product (resin) may be reduced.

In the present invention, "melt-mixing an acrylic polymer, an organic peroxide, an inorganic filler and a silane coupling agent to a polyolefin-based resin or rubber" specifies the mixing order when melt-mixing. It does not mean that they may be mixed in any order. The mixing order in the step (a) is not particularly limited. In the present invention, the inorganic filler is preferably used in a mixture with a silane coupling agent. That is, in the present invention, it is preferable that the above components are (melted) mixed in the following steps (a-1) and (a-2).
Step (a-1): Step of preparing a mixture by mixing at least an inorganic filler and a silane coupling agent Step (a-2): All or one of the mixture obtained in Step (a-1) and the base resin Part and an acrylic polymer, in the presence of an organic peroxide, at a temperature equal to or higher than the decomposition temperature of the organic peroxide, and melt-mixing the same.

The step (a-2) includes "an embodiment in which the entire amount (100 parts by mass) of the base resin is blended" and "an embodiment in which a part of the base resin is blended". When a part of the base resin is blended in the step (a-2), the remainder of the base resin is preferably blended in the step (b).
When a part of the base resin is blended in the step (a-2), 100 parts by mass of the base resin in the steps (a) and (b) are mixed in the steps (a-2) and (b). This is the total amount of base resin used.
Here, when the remainder of the base resin is blended in the step (b), the base resin is preferably blended in the step (a-2) in an amount of 55 to 99% by mass, more preferably 60 to 95% by mass, In the step (b), preferably 1 to 45% by mass, more preferably 5 to 40% by mass is blended.

In the present invention, the silane coupling agent is preferably premixed with the inorganic filler as described above (step (a-1)).
The method of mixing the inorganic filler and the silane coupling agent is not particularly limited, and examples thereof include a mixing method such as a wet treatment and a dry treatment. Specifically, a wet treatment in which the silane coupling agent is dispersed in a state in which the inorganic filler is dispersed in a solvent such as alcohol or water, or in an untreated inorganic filler, or in advance with stearic acid, oleic acid, a phosphate ester or Dry treatment in which a silane coupling agent is added with heating or non-heating to an inorganic filler whose part has been surface-treated with a silane coupling agent and mixed, and both of them are given. In the present invention, a dry treatment in which a silane coupling agent is added to or mixed with an inorganic filler, preferably a dried inorganic filler, with or without heating is preferred.
The silane coupling agent premixed in this manner exists so as to surround the surface of the inorganic filler, and a part or all of the silane coupling agent is adsorbed or bonded to the inorganic filler. Thereby, volatilization of the silane coupling agent at the time of subsequent melt mixing can be reduced. In addition, it is possible to prevent the silane coupling agent that does not adsorb or bind to the inorganic filler from condensing and making melt mixing difficult. Further, a desired shape can be obtained at the time of extrusion molding.

As such a mixing method, the inorganic filler and the silane coupling agent are preferably mixed at a temperature lower than the decomposition temperature of the organic peroxide, preferably at room temperature (25 ° C.), for several minutes to several hours, in a dry or wet manner. After (dispersion), a method of melt-mixing the mixture and the resin in the presence of an organic peroxide may be mentioned. This mixing is preferably performed by a mixer type mixer such as a Banbury mixer or a kneader. In this case, an excessive crosslinking reaction between the resin components can be prevented, and the appearance is excellent.
In this mixing method, a resin may be present as long as the temperature below the decomposition temperature is maintained. In this case, it is preferable that the metal oxide and the silane coupling agent are mixed together with the resin at the above temperature (step (a-1)) and then melt-mixed.

The method for mixing the organic peroxide is not particularly limited, as long as it is present when the mixture and the base resin are melt-mixed. The organic peroxide, for example, may be mixed simultaneously with the inorganic filler or the like, or may be mixed at any of the mixing stages of the inorganic filler and the silane coupling agent, to a mixture of the inorganic filler and the silane coupling agent They may be mixed. For example, the organic peroxide may be mixed with the inorganic filler after being mixed with the silane coupling agent, or may be separately mixed with the inorganic filler separately from the silane coupling agent. Depending on the production conditions, only the silane coupling agent may be mixed with the inorganic filler, and then the organic peroxide may be mixed.
The organic peroxide may be mixed with other components, or may be used alone.

  In the method of mixing the inorganic filler and the silane coupling agent, in wet mixing, since the bonding force between the silane coupling agent and the inorganic filler is increased, the volatilization of the silane coupling agent can be effectively suppressed. The condensation reaction may not easily proceed. On the other hand, in the dry mixing, the silane coupling agent is easily volatilized, but the bonding force between the inorganic filler and the silane coupling agent is relatively weak, so that the silanol condensation reaction easily proceeds easily.

  The method for mixing the acrylic polymer is not particularly limited, and may be any as long as it is present when the mixture and the base resin are melt-mixed.

Next, in the production method of the present invention, the obtained mixture, all or a part of the base resin, and the remaining components not mixed in the step (a-1) are treated with an organic peroxide in the presence of an organic peroxide. Melt and mix while heating to a temperature equal to or higher than the decomposition temperature of the peroxide (step (a-2)).
In the melt mixing in the step (a-2), the order of mixing the components is not particularly limited, and the components may be mixed in any order. For example, the above components may be melt-mixed at once, or the above-mentioned mixture or the like may be mixed after all or a part of the base resin is melted.

In the step (a-2), the temperature at which the above components are melted and mixed is a temperature equal to or higher than the decomposition temperature of the organic peroxide, preferably the decomposition temperature of the organic peroxide + (25 to 110) ° C, and more preferably. 150-230 ° C. The decomposition temperature is preferably set after the resin component has melted. At the mixing temperature, the components are melted, the organic peroxide is decomposed and acts, and the necessary silane graft reaction proceeds sufficiently in the step (a-2). Other conditions, for example, the mixing time can be set as appropriate.
The mixing method is not particularly limited as long as it is a method usually used for rubber, plastic, and the like. The mixing device is appropriately selected according to, for example, the blending amount of the inorganic filler. As the mixing device, a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, various kneaders, or the like is used. From the viewpoint of the dispersibility of the resin component and the stability of the crosslinking reaction, a closed mixer is preferable among Banbury mixers and various kneaders.
In addition, usually, when such an inorganic filler is mixed in an amount exceeding 100 parts by mass with respect to 100 parts by mass of the base resin, the mixture is melt-mixed in a closed mixer such as a continuous mixer, a pressurized kneader, and a Banbury mixer. Is good.
The method of mixing the base resin is not particularly limited. For example, the base resin may be directly mixed, or each component, for example, a resin component such as a polyolefin resin, an oil or a plasticizer may be separately mixed.

In the present invention, when the above components are melt-mixed at once, the conditions of the melt-mixing are not particularly limited, but the conditions of step (a-2) can be employed.
In this case, a part or all of the silane coupling agent is adsorbed or bonded to the inorganic filler during melt mixing.

  In the step (a), particularly the step (a-2), it is preferable to melt-mix the above-mentioned components without substantially mixing the silanol condensation catalyst. Thereby, the condensation reaction of the silane coupling agent can be suppressed, the mixture can be easily melt-mixed, and a desired shape can be obtained during extrusion molding. Here, "substantially not mixed" does not exclude the inevitably present silanol condensation catalyst, but exists to such an extent that the above-mentioned problem due to silanol condensation of the silane coupling agent does not occur. Also means good. For example, in the step (a-2), the silanol condensation catalyst may be present as long as it is 0.01 part by mass or less based on 100 parts by mass of the base resin.

In the step (a), the compounding amount of other resins and the above additives which can be used in addition to the above components is appropriately set within a range not to impair the object of the present invention.
In the step (a), the above additives, particularly the antioxidant and the metal deactivator, may be mixed in any step or with the component, but the grafting of the silane coupling agent mixed with the inorganic filler to the resin is carried out. It is advisable to mix it with the carrier resin in order not to hinder the reaction.
In the step (a), particularly in the step (a-2), it is preferable that the crosslinking aid is not substantially mixed. If the crosslinking aid is not substantially mixed, a crosslinking reaction between the resin components is unlikely to occur due to the organic peroxide during the melt mixing, and the appearance is excellent. Further, the graft reaction of the silane coupling agent to the resin hardly occurs, and the heat resistance is excellent. Here, “not substantially mixed” does not exclude the inevitable cross-linking aid, but means that it may be present to such an extent that the above-mentioned problem does not occur.

  Thus, the step (a) is performed to prepare a silane masterbatch (also referred to as silane MB) used for producing a masterbatch mixture. The silane MB contains a silane crosslinkable resin in which a silane coupling agent is grafted to a base resin to such an extent that it can be molded in step (b) described below. In the silane master batch, it is preferable that each component is uniformly dispersed.

Next, in the production method of the present invention, a step (b) of molding after mixing the silane MB obtained in the step (a) and the silanol condensation catalyst is performed.
In the step (b), when a part of the base resin is melt-mixed in the step (a-2), the remainder of the base resin and the silanol condensation catalyst are melt-mixed to form a catalyst masterbatch (also referred to as catalyst MB). It is preferably prepared and used. Note that, in addition to the rest of the base resin, another resin or the like may be added as needed.

The mixing ratio of the rest of the base resin as the carrier resin and the silanol condensation catalyst is not particularly limited, but is preferably set so as to satisfy the above-mentioned amount in the step (a).
The mixing may be any method as long as it can be uniformly mixed, and examples include mixing performed under melting of the base resin (melt mixing). The melt mixing can be performed in the same manner as the melt mixing in the step (a-2). For example, the mixing temperature is preferably, for example, 120 to 170C. Other conditions, for example, the mixing time can be set as appropriate.
The catalyst MB thus prepared is a mixture of a silanol condensation catalyst, a carrier resin, and a filler optionally added.

On the other hand, when the entire base resin is melt-mixed in step (a-2), in step (b), a silanol condensation catalyst itself or a mixture of another resin and a silanol condensation catalyst is used. The method for mixing the other resin with the silanol condensation catalyst is the same as that for the above-mentioned catalyst MB.
The compounding amount of the other resin is preferably 1 to 60 parts by mass with respect to 100 parts by mass of the base resin, because the grafting reaction can be promoted in the step (a-2), and there is little occurrence of bumps during molding. Part, more preferably 2 to 50 parts by mass, even more preferably 2 to 40 parts by mass.

In the production method of the present invention, silane MB and a silanol condensation catalyst (silanol condensation catalyst itself or catalyst MB or a mixture of silanol condensation catalyst and another resin) are mixed.
The mixing method may be any mixing method as long as a uniform mixture can be obtained as described above. For example, the mixing is basically the same as the melt mixing in the step (a-2). Although there is a resin component whose melting point cannot be measured by DSC or the like, for example, an elastomer, it is melt-mixed at least at a temperature at which the base resin melts. The melting temperature is appropriately selected according to the melting temperature of the base resin or the carrier resin, and is, for example, preferably 80 to 250 ° C, more preferably 100 to 240 ° C. Other conditions, for example, the mixing time can be set as appropriate.
In step (b), in order to avoid a silanol condensation reaction, it is preferable that the silane MB and the silanol condensation catalyst are not kept at a high temperature for a long time in a mixed state.

  In the step (b), the silane MB and the silanol condensation catalyst may be mixed, and when the silane MB and the catalyst MB are used, it is preferable that they are melt-mixed.

  In the present invention, the silane MB and the silanol condensation catalyst can be dry-blended before being melt-mixed. The method and conditions of the dry blending are not particularly limited, and include, for example, dry mixing in step (a-1) and its conditions. By this dry blending, a master batch mixture containing silane MB and a silanol condensation catalyst is obtained.

  In the step (b), an inorganic filler may be used. In this case, the amount of the inorganic filler is not particularly limited, but is preferably 350 parts by mass or less based on 100 parts by mass of the carrier resin. If the amount of the inorganic filler is too large, the silanol condensation catalyst is difficult to disperse, and the crosslinking is difficult to progress. On the other hand, if the amount of the inorganic filler is too small, the degree of cross-linking of the molded article is reduced, and sufficient heat resistance may not be obtained.

  In the present invention, the mixing of the steps (a) and (b) can be performed simultaneously or continuously.

In the step (b), the mixture thus obtained is molded.
In this molding step, it is sufficient that the mixture can be molded, and a molding method and molding conditions are appropriately selected according to the form of the heat-resistant product of the present invention. Examples of the molding method include extrusion molding using an extruder.

In the step (b), the molding step can be performed simultaneously or continuously with the mixing step. That is, as one embodiment of the melt mixing in the mixing step, there is an embodiment in which the forming raw materials are melt mixed at the time of melt molding, for example, at the time of, or immediately before, extrusion molding. For example, pellets such as a dry blend may be mixed at room temperature or high temperature and introduced into a molding machine (melt mixing), or they may be mixed and melt-mixed, then pelletized again, and introduced into a molding machine. Is also good. More specifically, a series of steps of melt-mixing a mixture (molding material) of silane MB and a silanol condensation catalyst in a coating apparatus, and then extruding and coating the outer peripheral surface of a conductor or the like to form a desired shape. Can be adopted.
Thus, a silane masterbatch and a silanol condensation catalyst are dry-blended to prepare a masterbatch mixture, and the masterbatch mixture is introduced into a molding machine and molded to obtain a molded body of the silane crosslinkable resin composition. .

Here, the molten mixture of the master batch mixture contains silane crosslinkable resins having different crosslinking methods. In the silane crosslinkable resin, the reaction site of the silane coupling agent may be bonded or adsorbed to the inorganic filler, but is not silanol-condensed as described later. Therefore, the silane crosslinkable resin, the silane coupling agent bonded or adsorbed to the inorganic filler, the base resin, grafted crosslinkable resin, the silane coupling agent not bonded or adsorbed to the inorganic filler was grafted to the base resin. At least a crosslinkable resin. Further, the silane crosslinkable resin may have a silane coupling agent to which an inorganic filler is bonded or adsorbed, and a silane coupling agent to which an inorganic filler is not bonded or adsorbed. Further, it may contain a resin component that has not reacted with the silane coupling agent.
As described above, the silane crosslinkable resin is an uncrosslinked body in which the silane coupling agent has not been subjected to silanol condensation. Actually, when melt-mixed in the step (b), partial cross-linking (partial cross-linking) is unavoidable, but the obtained silane cross-linkable resin composition retains at least the moldability at the time of molding. And
Like the above mixture, the molded article obtained in the step (b) is in a partially crosslinked state in which the crosslinkability cannot be avoided, but retains the moldability that can be molded in the step (b). Therefore, the silane crosslinked resin molded article of the present invention is a crosslinked or finally crosslinked molded article by performing the step (c).

In the method for producing a silane crosslinked resin molded article of the present invention, a step (c) of bringing the molded article obtained in the step (b) into contact with water is performed. As a result, the reaction site of the silane coupling agent is hydrolyzed to silanol, and the hydroxyl groups of silanol are condensed by the silanol condensation catalyst present in the molded body to cause a crosslinking reaction. In this way, a silane crosslinked resin molded product in which the silane coupling agent is silanol condensed and crosslinked can be obtained.
The processing itself of the step (c) can be performed by a usual method. Condensation between silane coupling agents proceeds only by storage at room temperature. Therefore, in the step (c), there is no need to positively contact the molded body with water.
In order to accelerate this crosslinking reaction, the molded article can be brought into contact with moisture. For example, a method of positively contacting with water, such as immersion in warm water, introduction into a wet heat tank, or exposure to high-temperature steam, can be adopted. At that time, pressure may be applied to make water permeate inside.

  In this way, the method for producing a silane crosslinked resin molded article of the present invention is performed, and a silane crosslinked resin molded article is produced. This silane crosslinked resin molded article contains a crosslinked resin in which a (silane crosslinkable) resin is condensed via a silanol bond (siloxane bond). One form of the silane crosslinked resin molded body contains a silane crosslinked resin and an inorganic filler. Here, the inorganic filler may be bonded to the silane coupling agent of the silane crosslinked resin. Therefore, the present invention includes an embodiment in which the base resin is crosslinked with the inorganic filler via a silanol bond. Specifically, the silane cross-linked resin is obtained by bonding or adsorbing a plurality of cross-linked resins to an inorganic filler with a silane coupling agent, and bonding (cross-linking) the inorganic resin and the silane coupling agent via the silane coupling agent, The reaction site of the silane coupling agent grafted on the crosslinkable resin is hydrolyzed to cause a silanol condensation reaction with each other, thereby containing at least a crosslinked resin crosslinked via the silane coupling agent. In the silane cross-linked resin, a bond (cross-linking) via an inorganic filler and a silane coupling agent and a cross-linking via a silane coupling agent may be mixed. Further, it may contain a resin component not reacted with the silane coupling agent and / or a silane crosslinkable resin that is not crosslinked.

The manufacturing method of the present invention can be expressed as follows.
A method for producing a silane crosslinked resin molded article having the following steps (A), (B) and (C), wherein step (A) comprises the following steps (A1) to (A4): How to make the body.
Step (A): 0.1 to 20 parts by mass of an acrylic polymer, 0.003 to 0.3 parts by mass of an organic peroxide, and 0.5 of an inorganic filler with respect to 100 parts by mass of a polyolefin-based resin or rubber. Step (B) of mixing -400 parts by mass, more than 2 parts by mass of the silane coupling agent and not more than 15.0 parts by mass, and the silanol condensation catalyst to obtain a mixture. Step (B): Step (C) of obtaining a molded article by molding: Step (A1) of obtaining a silane-crosslinked resin molded article by bringing the molded article obtained in step (B) into contact with water: at least an inorganic filler and a silane coupling agent (A2): a step of melt-mixing the mixture obtained in the step (A1) and all or a part of the base resin at a temperature not lower than the decomposition temperature of the organic peroxide in the presence of the organic peroxide. Step (A3): Silano (A4): mixing the molten mixture obtained in the step (A2) and the mixture obtained in the step (A3) with the condensation catalyst and a resin different from the base resin or the remainder of the base resin as the carrier resin. Step of mixing In the above method, the step (A) corresponds to the mixing of the steps (a) and (b), the step (B) corresponds to the molding step of the step (b), and the step (C) ) Corresponds to step (c) above. In addition, the step (A1) corresponds to the step (a-1), the step (A2) corresponds to the step (a-2), and the steps (A3) and (A4) correspond to the step (b). Each corresponds.

Although the details of the reaction mechanism in the production method of the present invention are not yet clear, it is considered as follows.
That is, before and / or during kneading with the base resin, by using (mixing) the inorganic filler and the silane coupling agent, the silane coupling agent binds to the inorganic filler with a chemically bondable group, The non-crosslinked portion of the resin component is bonded to and retained by a group capable of performing a graft reaction at the other end. Alternatively, the silane coupling agent is physically or chemically adsorbed to the holes or surfaces of the inorganic filler without being bonded to the inorganic filler by a group capable of chemically bonding, and the resin component is a group capable of performing a graft reaction. It is bound and retained by the uncrosslinked portion. As described above, the silane coupling agent that binds to the inorganic filler with a strong bond (the reason is considered to be, for example, the formation of a chemical bond with a hydroxyl group or the like on the surface of the inorganic filler) is considered as the silane coupling agent that binds with the weak bond ( The reason is, for example, an interaction due to a hydrogen bond, an interaction between ions, partial charges or dipoles, an effect due to adsorption, and the like can be formed. In this state, when the organic peroxide is added and kneaded with the base resin, the silane coupling agent hardly volatilizes as described above, and the condensation between the silane coupling agents is suppressed, and the inorganic filler and A silane crosslinkable resin is formed by grafting a silane coupling agent having a different bond to a resin component.

Even by the above-described kneading, the silane coupling agent having a strong bond with the inorganic filler among the silane coupling agents retains the bond with the inorganic filler, and a group capable of performing a graft reaction, which is a cross-linking group, is formed at a cross-linking site of the resin component. Perform a graft reaction. In particular, when a plurality of silane coupling agents are bonded to the surface of one inorganic filler particle via a strong bond, a plurality of resin components are bonded via the inorganic filler particle. By these reactions or bonds, a crosslinked network via the inorganic filler is expanded. That is, a silane crosslinkable resin formed by a graft reaction of the silane coupling agent bonded to the inorganic filler to the resin component is formed.
The silane coupling agent having a strong bond with the inorganic filler hardly causes a condensation reaction in the presence of water by the silanol condensation catalyst, and the bond with the inorganic filler is maintained. It is considered that the reason why the silanol condensation reaction hardly occurs is that the binding energy between the inorganic filler and the silane coupling agent is extremely high, and the condensation reaction does not occur even under the silanol condensation catalyst. As described above, the binding between the resin component and the inorganic filler occurs, and the crosslinking of the resin component via the silane coupling agent occurs. Thereby, the adhesion between the resin component and the inorganic filler is strengthened, and a molded article having good mechanical strength and abrasion resistance and resistant to scratching is obtained. In particular, a plurality of silane coupling agents can be bonded to the surface of one inorganic filler particle, and high mechanical strength can be obtained. As described above, the silane coupling agent bonded by a strong bond to the inorganic filler is considered to contribute to the development or improvement of scratch resistance, mechanical properties, and in some cases, wear resistance.

  On the other hand, among the silane coupling agents, the silane coupling agent having a weak bond with the inorganic filler is separated from the surface of the inorganic filler by the above-described kneading, and a group capable of performing a graft reaction which is a crosslinking group of the silane coupling agent. Reacts with radicals of the resin component generated by abstraction of hydrogen radicals by radicals generated by decomposition of the organic peroxide to cause a graft reaction. That is, a silane crosslinkable resin is formed in which the silane coupling agent released from the inorganic filler undergoes a graft reaction to the resin component. The silane coupling agent in the graft portion thus generated is then mixed with a silanol condensation catalyst and brought into contact with moisture to cause a condensation reaction (crosslinking reaction). The heat resistance of the silane cross-linked resin molded product obtained by this cross-linking reaction increases. As described above, it is considered that the silane coupling agent bonded to the inorganic filler by a weak bond contributes to improvement in the degree of crosslinking, that is, improvement in heat resistance.

  Furthermore, when the silane coupling agent is mixed with the inorganic filler in advance by the production method of the present invention, the appearance is excellent because the condensation between the silane coupling agents is suppressed as described above.

In the production method of the present invention, a polyolefin resin or rubber is used as a base resin, and when an acrylic polymer is used in combination at a specific ratio, it is possible to prevent mold during extrusion molding, and to a silane crosslinked resin molded article, Excellent appearance can be provided without impairing heat resistance. The details of the fact that such excellent properties can be imparted to the silane cross-linked resin molded body are not yet clear, but are considered as follows.
That is, when the above-mentioned polyolefin-based resin or rubber and the acrylic polymer are used together in a specific ratio, the graft reaction is not hindered at the time of preparing the silane master batch, and an excessive graft reaction hardly occurs. Further, a condensation reaction between silanol groups hardly occurs. This is probably because the acrylic polymer does not have the function of a metal catalyst. Thereby, the occurrence of gel spots is reduced, and a molded article having excellent appearance can be obtained.
In addition, the polyolefin-based resin or rubber and the acrylic polymer are highly compatible, and particularly high-molecular-weight acrylic copolymers are easily entangled with the base resin, and the melt elasticity of the molten mixture is increased. Since it works, the dispersibility of other components such as a silane coupling agent and an inorganic filler is enhanced by the acrylic polymer. Thereby, crosslinking and the like proceed uniformly, and it is possible to suppress a decrease in physical properties such as heat resistance of the molded article.
Furthermore, since a part of the acrylic polymer is exposed on the surface of the molten mixture (or the silane crosslinkable resin molded product), the adhesiveness of the molten mixture can be reduced. Thereby, the friction between the die of the extruder and the molten mixture is reduced, and the generation of resin scum at the die outlet can be suppressed.
In the present invention, when these are exerted in a well-balanced manner, it is possible to reduce the occurrence of mold buildup during molding and to impart excellent appearance and heat resistance to the silane crosslinked resin molded article.

The production method of the present invention can be applied to the production of components (including semi-finished products, parts, and members) requiring heat resistance, components of products such as rubber materials, and members thereof. Therefore, the heat-resistant product of the present invention is a product having heat resistance as described above. At this time, the heat-resistant product may be a product containing a silane cross-linked resin molded product, or may be a product composed of only a silane cross-linked resin molded product.
Examples of the heat-resistant product of the present invention include not only coating materials for heat-resistant electric wires or cables, but also rubber mold materials requiring heat resistance (eg, glass run channels for automobiles, weather strips, rubber hoses, wiper blade rubbers, vibration-proof rubbers). ), Polyolefin material products that have undergone a crosslinking or chemical vulcanization step by electron beam irradiation, and alternative products to EP rubber products.

The production method of the present invention is suitably applied to the production of electric wires and optical fiber cables among the above products, and can form a coating material (insulator or sheath) thereof.
When the heat-resistant product of the present invention is an electric wire or a cable, preferably, the molding material is melt-kneaded in an extruder (extrusion coating apparatus) to prepare the silane-crosslinkable resin composition. The composition can be manufactured by extruding the composition to the outer periphery of a conductor or the like and coating the conductor or the like. Such a heat-resistant product can be produced by adding a large amount of an inorganic filler to a silane crosslinkable resin composition without using special equipment such as an electron beam crosslinker using a general-purpose extrusion coating apparatus to form a resin around the conductor. Alternatively, it can be formed by extrusion-coating a tensile strength fiber around a vertically laid or twisted conductor. For example, as the conductor, a single wire or a stranded wire of soft copper, a copper alloy, aluminum or the like can be used. In addition to the bare wire, a tin-plated conductor or a conductor having an enamel-coated insulating layer can be used as the conductor. The thickness of the insulating layer formed around the conductor (the coating layer formed of the silane cross-linked resin molded article of the present invention) is not particularly limited, but is usually about 0.15 to 5 mm.
When extruding an electric wire, the temperature of the extruder depends on the type of resin and various conditions such as the take-up speed of the conductor, etc., but it is 120 to 150 ° C. in the cylinder part and about 160 to 180 ° C. in the cross head part. It is preferable to set the degree.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
In Tables 1 and 2, numerical values relating to the blending amount in each example represent parts by mass unless otherwise specified.

Examples 1 to 6, 10 to 14 , Reference Examples 7 to 9 and Comparative Examples 1 to 8 were carried out using the following components by setting the respective parameters to the conditions shown in Tables 1 and 2, Tables 1 and 2 also show the evaluation results described later.

The following components were used as the components shown in Tables 1 and 2.
<Base resin>
(Polyolefin resin or rubber)
Ethylene-α-olefin copolymer rubber: Nodel 3720P (trade name, manufactured by Dow, ethylene-propylene-ethylidene norbornene rubber, ethylene component content 70% by mass, diene component content 0.5% by mass)
Ethylene-α-olefin copolymer rubber: EPT0045 (trade name, manufactured by Mitsui Chemicals, Inc., ethylene-propylene rubber, ethylene component content 51% by mass, diene component content 0% by mass)
Resin of ethylene-α-olefin copolymer: Sumikacene CU5003 (trade name, manufactured by Sumitomo Chemical Co., Ltd., metallocene low density polyethylene, density 0.928 g / cm ³ )
Ethylene-vinyl acetate copolymer: VF120S (trade name, manufactured by Ube Industries, Ltd., vinyl acetate component content 20%)
Ethylene-acrylate copolymer: NUC6510 (trade name, manufactured by NUC, ethylene-ethyl acrylate copolymer, acrylate component content 23% by mass, density 0.93 g / cm ³ )
(Other components)
Styrenic thermoplastic elastomer: Tuftec N504 (trade name, manufactured by Asahi Kasei Chemicals Corporation, hydrogenated SEBS)
Mineral oil: Diana process oil PW90 (trade name, manufactured by Idemitsu Kosan Co., Ltd., paraffin oil)
Silane grafter: Linklon XCF730N (trade name, manufactured by Mitsubishi Chemical Corporation, resin obtained by silane grafting of linear low-density polyethylene)
<Inorganic filler>
McSeeds FK621 (trade name, manufactured by Kamishima Chemical Co., Ltd., magnesium hydroxide)
<Additive)
Acrylic polymer 1: Metablen L-1000 (trade name, manufactured by Mitsubishi Rayon Co., Ltd., weight average molecular weight 270,000)
Acrylic polymer 2: Metablen P-501A (trade name, manufactured by Mitsubishi Rayon Co., Ltd., mass average molecular weight 800,000)
Acrylic polymer 3: Metablen P-530A (trade name, manufactured by Mitsubishi Rayon Co., Ltd., weight average molecular weight 3.1 million)
Acrylic polymer 4: ARUFON UP-1170 (trade name, manufactured by Toagosei Co., Ltd., mass average molecular weight: 88,000)
Fluoropolymer: Metablen A-3300 (trade name, manufactured by Mitsubishi Rayon Co., Ltd., acrylic-modified polytetrafluoroethylene)
Oleic amide: Armoslip CP (trade name, manufactured by Lion Specialty Chemicals)
Calcium stearate: Ca-St (trade name, manufactured by Nitto Kasei)
Silicone gum: X-21-3043 (trade name, manufactured by Shin-Etsu Silicone Co., Ltd.)
Polyethylene wax: AC polyethylene No. 6 (trade name, manufactured by Honeywell)
<Silane coupling agent>
KBM1003 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., vinyltrimethoxysilane)
<Organic peroxide)
Perhexa 25B (trade name, manufactured by NOF CORPORATION, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, decomposition temperature 179 ° C)
<Silanol condensation catalyst>
ADK STAB OT-1 (trade name, manufactured by ADEKA, dioctyltin dilaurate)

(Examples 1 to 6, 10 to 13 , Reference Examples 7 to 9 , Comparative Examples 1 to 8)
First, an inorganic filler and a silane coupling agent were charged into a 10 L Henschel mixer manufactured by Toyo Seiki Co., Ltd. at the mass ratios shown in Tables 1 and 2, and mixed at room temperature (25 ° C.) for 1 hour to obtain a powder mixture. Was. Here, such a mixing method is referred to as pre-blend (PB).
Next, each component shown in the base resin column of Table 1 and Table 2 was charged into a 2 L Banbury mixer made by Nippon Roll, and each component was melted. Thereafter, the powder mixture, the organic peroxides shown in Tables 1 and 2, and the components shown in the additive column were charged into the Banbury mixer at the mass ratios shown in Tables 1 and 2, and the organic peroxide was added. After melting and mixing at a temperature higher than the decomposition temperature of the substance, specifically at 190 ° C. for 10 minutes, the mixture was discharged at a material discharge temperature of 190 ° C. to obtain silane MB. The obtained silane MB contains a silane crosslinkable resin obtained by grafting a silane coupling agent to a base resin.

  Next, the silane MB and the silanol condensation catalyst were charged into a closed ribbon blender, and were dry-blended at room temperature (25 ° C.) for 5 minutes to obtain a dry blend (master batch mixture). At this time, the mixing ratio between the silane MB and the silanol condensation catalyst is the mass ratio shown in Tables 1 and 2.

Next, the obtained dry blend was introduced into a 25 mmφ extruder (L / D (ratio of effective screw length L to diameter D) = 25). While melting and mixing the dry blend in this extruder, under the following extrusion temperature conditions, around the conductor (bare soft copper wire, 0.8 mmφ), the outer diameter is 2.4 mmφ, and the insulation thickness is 0.8 mm. Coating was performed at a linear velocity of 10 m / min to obtain a coated conductor.
As for the temperature conditions, the die temperature in the extruder was set to 200 ° C., and the C3 zone was set to 180 ° C., the C2 zone was set to 150 ° C., and the C1 zone was set to 130 ° C.
The obtained coated conductor was allowed to stand at room temperature (23 ° C., 50% RH) for 24 hours to bring the coated conductor (molded product of the silane crosslinkable composition) into contact with water.
Thus, an electric wire having a coating layer made of a silane cross-linked resin molded product on the outer peripheral surface of the conductor was manufactured. The silane crosslinked resin molded article as the coating layer has the above silane crosslinked resin.

(Example 14)
Without preparing the powder mixture, each component shown in the base resin column of Table 1, inorganic filler, silane coupling agent, organic peroxide, and each component shown in the additives column, by mass ratio shown in Table 1, Silane MB was obtained in the same manner as in Example 2 except that it was charged into a 2 L Banbury mixer manufactured by Nippon Roll. Here, such simultaneous mixing is called all blend (AB: All Blend).
Further, a coated conductor and an electric wire were obtained in the same manner as in Example 2 except that the silane MB obtained above was used.

  The following tests were performed on the manufactured electric wires, and the results are shown in Tables 1 and 2.

1. When the wire was extruded under the conditions described above, the production length at the time when the wire adhered to the surface of the wire was measured. When the production length is 1000 m or more, A (excellent), 500 m or more and less than 1000 m B (excellent), 300 m or more and less than 500 m C (good), 200 m or more and less than 300 m D (good), and 200 m or less less E (good) Failed).

2. Appearance At the time of electric wire production, "AA (advanced)" when the surface of the electric wire is very clean and good appearance, and "A (good)""E" (rejected) indicates that the surface of the electric wire has gel spots or roughness.

3. Bleed-out (reference test)
The manufactured electric wire was left in an environment of 23 ° C. and 50% RH. "A (advanced)" indicates that there is no change in the surface of the electric wire visually even after leaving it for more than 6 months. "B", and those oozing in less than one month were designated "E". This evaluation is a reference test.

4. Heat shrinkage Heat shrinkage was measured in order to confirm whether sufficient crosslinking had proceeded and had heat resistance.
After the conductor was pulled out from the manufactured electric wire to obtain a 200 mm tubular piece, it was left in a thermostat at 100 ° C. for 22 hours, then left at room temperature for 3 hours, and the heat shrinkage was calculated by the following equation.
Heat shrinkage (%) = {(initial length)-(length after heating)} / (initial length) × 100
"A (high grade)" when the heat shrinkage is less than 3%, "B (good)" when 3% or more and less than 5%, "C (good)" when 5% or more and less than 8%, 8 % Or more was evaluated as “E (fail)”.

As is clear from the results shown in Tables 1 and 2, all of Examples 1 to 6, and 10 to 14 passed the measurement test, the appearance test, and the heat shrinkage test. As described above, according to the present invention, an electric wire having a coating layer of a silane cross-linked resin molded product having reduced appearance of heat generation during extrusion molding, capable of continuous extrusion of 1,000 m or more, and having excellent appearance and heat resistance is provided. It could be manufactured.
Furthermore, in each of Examples 1 to 6, 10 to 12, and 14 using an acrylic polymer having a mass average molecular weight of 100,000 or more, bleed out was suppressed. According to the present invention, an electric wire having a silane cross-linked resin molded article having a more excellent appearance as a coating layer in addition to the above-mentioned excellent properties can be produced.

  On the other hand, in Comparative Example 1 using the fluorine-based polymer, rust occurred when the production length was less than 200 m, and the appearance of the obtained electric wire was poor. In Comparative Example 2 in which oleic acid amide was used, scum was generated when the production length was less than 200 m. Comparative Example 3 using calcium stearate was inferior in appearance. In each of Comparative Example 4 using silicone gum and Comparative Example 5 using polyethylene wax, scum occurred when the production length was less than 200 m. In Comparative Example 6 in which silane MB containing too little acrylic polymer was used, scumming occurred when the production length was less than 200 m. Comparative Example 7, which used silane MB containing too much acrylic polymer, failed the heat shrink test. Bleed-out was also observed. Comparative Example 8 using a silane graftmer as the base resin failed the heat shrink test.

Claims (13)

A polyolefin- based base rubber containing an ethylene-α-olefin copolymer rubber or containing an ethylene-α-olefin copolymer rubber and a styrene-based thermoplastic elastomer (however, excluding an ethylene-vinyl acetate copolymer) ) With respect to 100 parts by mass, 0.1 to 20 parts by mass of an acrylic polymer, 0.003 to 0.3 parts by mass of an organic peroxide, 0.5 to 400 parts by mass of an inorganic filler, and silane coupling. More than 2 parts by mass of the agent and not more than 15.0 parts by mass are melt-mixed at a temperature not lower than the decomposition temperature of the organic peroxide , and a graft reaction is performed between the polyolefin base rubber and the silane coupling agent to form a silane. Step (a) of preparing a silane masterbatch containing a crosslinkable resin ,
(B) shaping after mixing the silane master batch obtained in the step (a) and the silanol condensation catalyst;
A step (c) of bringing the molded body obtained in the step (b) into contact with moisture to crosslink,
A method for producing a silane crosslinked resin molded article having:   The method for producing a silane crosslinked resin molded article according to claim 1, wherein the acrylic polymer has a mass average molecular weight of 100,000 to 1,000,000. The method for producing a silane crosslinked resin molded product according to claim 1 or 2, wherein the acrylic polymer is 0.5 to 10 parts by mass based on 100 parts by mass of the polyolefin- based rubber . The method for producing a silane crosslinked resin molded product according to any one of claims 1 to 3, wherein the acrylic polymer is 1 to 6 parts by mass based on 100 parts by mass of the polyolefin- based rubber .   The method for producing a silane crosslinked resin molded product according to any one of claims 1 to 4, wherein the silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane.   The method for producing a silane crosslinked resin molded product according to any one of claims 1 to 5, wherein the inorganic filler includes silica, boehmite, clay, talc, aluminum hydroxide, magnesium hydroxide, calcium carbonate, or a combination thereof. .   The method for producing a silane crosslinked resin molded article according to any one of claims 1 to 6, wherein the melt mixing in the step (a) is performed using a closed mixer. A polyolefin- based base rubber containing an ethylene-α-olefin copolymer rubber or containing an ethylene-α-olefin copolymer rubber and a styrene-based thermoplastic elastomer (however, excluding an ethylene-vinyl acetate copolymer) ) 100 parts by mass, 0.1 to 20 parts by mass of an acrylic polymer, 0.003 to 0.3 parts by mass of an organic peroxide, 0.5 to 400 parts by mass of an inorganic filler, and a silane coupling agent A silane master batch used for producing a master batch mixture obtained by mixing more than 2 parts by mass and not more than 15.0 parts by mass with a silanol condensation catalyst,
The base rubber, the acrylic polymer, the organic peroxide, the inorganic filler, and the silane coupling agent are melt-mixed at a temperature equal to or higher than the decomposition temperature of the organic peroxide, and the polyolefin-based rubber and the silane are mixed. A silane masterbatch containing a silane crosslinkable resin obtained by performing a graft reaction with a coupling agent .   A master batch mixture containing the silane master batch according to claim 8 and a silanol condensation catalyst. A molded product obtained by molding a master batch mixture obtained by dry blending the silane master batch according to claim 9 and a silanol condensation catalyst.   A silane crosslinked resin molded article produced by the method for producing a silane crosslinked resin molded article according to claim 1. The silane crosslinked resin molded product according to claim 11, wherein the base rubber is crosslinked with the inorganic filler via a silanol bond. A heat-resistant product comprising the silane crosslinked resin molded product according to claim 11.