JP6782222B2 - Silane-crosslinked acrylic rubber molded article and its manufacturing method, silane-crosslinked acrylic rubber composition, and oil-resistant products - Google Patents

Description

The present invention relates to a silane crosslinked acrylic rubber molded product and a method for producing the same, a silane crosslinked acrylic rubber composition, and an oil resistant product.

Insulated wires, cables, cords, optical fiber core wires or optical fiber cord wiring materials used for internal or external wiring of electrical and electronic equipment have flame retardancy and mechanical properties (eg, tensile strength, breakage). Various characteristics such as elongation), abrasion resistance, and appearance are required.

In the wiring material as described above, the resin or rubber forming the coating layer may be crosslinked in order to improve its characteristics. As a method for cross-linking the resin or rubber, an electron beam cross-linking method or a chemical cross-linking method is generally used. For example, as a method for cross-linking a polyolefin resin such as polyethylene, an electron beam cross-linking method in which an electron beam is irradiated for cross-linking, or a cross-linking method in which an organic peroxide or the like is decomposed by applying heat after molding to carry out a cross-linking reaction. And chemical cross-linking methods such as the silane cross-linking method can be mentioned.
Here, the silane cross-linking method is to obtain a silane graft resin by subjecting a resin to a silane grafting reaction (simply referred to as a grafting reaction) with a silane coupling agent having an unsaturated group in the presence of an organic peroxide. This is a method of obtaining a crosslinked resin by contacting the silane graft resin with water in the presence of a silanol condensation catalyst.
Among the above-mentioned cross-linking methods, the silane cross-linking method often does not require special equipment, and therefore can be used in a wide range of fields.

As an example of applying the silane cross-linking method, for example, Patent Document 1 describes an inorganic filler, a silane coupling agent, and an organic filler in which a resin component obtained by mixing a polyolefin resin and a maleic anhydride-based resin is surface-treated with a silane coupling agent. A method has been proposed in which the peroxide and the cross-linking catalyst are sufficiently melt-kneaded with a kneader and then molded with a uniaxial extruder.

Japanese Unexamined Patent Publication No. 2001-101928

However, in the method described in Patent Document 1, silane coupling agents other than the silane coupling agent that surface-treats the inorganic filler during melt-kneading with a kneader or the like are condensed with each other, resulting in poor appearance of the molded product. There is a problem of causing.

On the other hand, these wiring materials and cables may be used by being immersed in oil (in a state where they can come into contact with machine oil or the like). Wiring materials and the like used for such applications are required to have oil resistance (characteristics that the deterioration of physical properties is small even when oiled). In such a case, a wiring material using a resin material or a rubber material having excellent oil resistance for the coating layer is used as the wiring material.
Polyolefin resin such as polyethylene or acrylic rubber is used as a material having excellent oil resistance for the coating layer of the wiring material. However, even a molded product obtained by using such a resin or rubber has not been sufficient as a molded product for wiring materials in terms of mechanical properties, flame retardancy, and abrasion resistance.

The present invention provides a silane crosslinked acrylic rubber molded product, a method for producing the same, and an oil resistant product, which overcomes the above problems and has excellent appearance, oil resistance, wear resistance, mechanical properties, and flame retardancy. Is the subject.
Another object of the present invention is to provide a silane crosslinked acrylic rubber composition capable of forming the silane crosslinked acrylic rubber molded product.

The present inventors prepare a silane masterbatch using a base rubber containing a specific amount of ethylene-acrylic rubber and a polyolefin resin modified with an unsaturated carboxylic acid component, and a catalyst master containing a silanol condensation catalyst or a silanol condensation catalyst. When a silane-crosslinked acrylic rubber molded product is produced by a specific manufacturing method in which a batch is mixed, the obtained silane-crosslinked acrylic rubber molded product has an appearance while maintaining sufficient flame retardancy and mechanical properties as a molded product for wiring materials. , It was found that each property of oil resistance and abrasion resistance can be imparted at an excellent level. Based on this finding, the present inventors further conducted research and came to the present invention.

That is, the subject of the present invention has been achieved by the following means.
[1] The following steps (1), steps (2) and steps (3)
Step (1): In the presence of 0.01 to 0.5 parts by mass of the organic peroxide, 40 to 250 parts by mass of the inorganic filler, and radicals generated from the organic peroxide with respect to 100 parts by mass of the base rubber. 1 to 15 parts by mass of a silane coupling agent having a grafting reaction site capable of crosslinking with the base rubber and a silanol condensation catalyst are melt-mixed, and the graft is generated by radicals generated from the organic peroxide. A reaction composition containing a silane crosslinkable rubber is obtained by subjecting the radicalization reaction site and the grafting reaction site of the base rubber having the grafting reaction site and the grafting reaction capable site to a grafting reaction. Step Step (2): A step of molding the reaction composition to obtain a molded body Step (3): A silane crosslinked acrylic rubber having a step of bringing the molded body into contact with water to obtain a silane crosslinked acrylic rubber molded body. It is a method of manufacturing a molded body,
The base rubber contains 55 to 95% by mass of ethylene-acrylic rubber and 5 to 45% by mass of a polyolefin resin modified with an unsaturated carboxylic acid component.
When the step (1) has the following steps (a-1), steps (a-2) and steps (c), but a part of the base rubber is melt-mixed in the following steps (a-2). Has the following steps (a-1), steps (a-2), steps (b) and steps (c).
Step (a-1): At least the inorganic filler and the silane coupling agent are mixed to prepare a mixture. Step (a-2): The mixture and all or a part of the base rubber are mixed with the organic catalyst. In the presence of the oxide, the organic peroxide is melt-mixed at a temperature equal to or higher than the decomposition temperature of the organic peroxide, and the radical generated from the organic peroxide causes the grafting reaction site and the grafting reaction site of the base rubber. Step (b): Step of preparing a catalyst master batch by melt-mixing the rest of the base rubber and the silanol condensation catalyst. Step (b): Step of preparing a silane master batch containing a silane crosslinkable rubber. (C): A step of melt-mixing the silane master batch with the silanol condensation catalyst or the catalyst master batch to obtain a reaction composition. A method for producing a silane crosslinked acrylic rubber molded product.
[2] The base rubber contains 70 to 85% by mass of ethylene-acrylic rubber and 15 to 30% by mass of a polyolefin resin modified with an unsaturated carboxylic acid component.
The method for producing a silane crosslinked acrylic rubber molded product according to [1], which contains 80 to 200 parts by weight of the inorganic filler.
[3] The ethylene-acrylic rubber contains a binary copolymer of ethylene and an acrylic acid alkyl ester, and a ternary copolymer of ethylene, an acrylic acid alkyl ester and a copolymer component containing a carboxy group. The method for producing a silane-crosslinked acrylic rubber polymer according to [1] or [2].
[4] Production of the silane crosslinked acrylic rubber molded product according to [3], wherein the ethylene-acrylic rubber contains 25 to 45% by mass of the binary copolymer and 20 to 60% by mass of the ternary copolymer. Method.
[5] The method for producing a silane crosslinked acrylic rubber molded product according to any one of [1] to [4], wherein the inorganic filler is a metal hydrate.
[6] The silane crosslinked acrylic rubber molding according to any one of [1] to [5], wherein the content of the silane coupling agent is 3 to 15 parts by mass with respect to 100 parts by mass of the base rubber. How to make a body.
[7] The method for producing a silane crosslinked acrylic rubber molded product according to any one of [1] to [6], wherein the silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane.
[8] The silane crosslinked acrylic rubber molded product according to any one of [1] to [7], wherein the silanol condensation catalyst is not substantially mixed in the steps (a-1) and (a-2). Production method.
[9] A silane crosslinkable acrylic rubber composition produced by the step (1) according to any one of [1] to [8].
[10] A silane-crosslinked acrylic rubber molded product produced by the method for producing a silane-crosslinked acrylic rubber molded product according to any one of [1] to [8].
[11] An oil-resistant product containing the silane crosslinked acrylic rubber molded product according to [10].
[12] The oil-resistant product according to [11], wherein the silane crosslinked acrylic rubber molded product is a coating of an electric wire or an optical fiber cable.

The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

The method for producing a silane cross-linked acrylic rubber molded product of the present invention overcomes the problems of the conventional silane cross-linking method, and has excellent appearance, oil resistance, abrasion resistance, mechanical properties, and flame retardancy. A rubber molded product can be manufactured.
Therefore, according to the present invention, it is possible to provide a silane crosslinked acrylic rubber molded product having excellent appearance, oil resistance, abrasion resistance, mechanical properties, and flame retardancy, a method for producing the same, and an oil resistant product. Further, it is possible to provide a silane crosslinked acrylic rubber composition capable of forming a silane crosslinked acrylic rubber molded product exhibiting such excellent properties.

First, each component used in the present invention will be described.

<Base rubber>
The base rubber used in the present invention contains ethylene-acrylic rubber as a rubber component and a polyolefin resin modified with an unsaturated carboxylic acid component. All of these resins have a grafting reaction site of a silane coupling agent and a site capable of a grafting reaction in the presence of radicals generated from an organic peroxide, for example, an unsaturated bond site of a carbon chain or a hydrogen atom. It has a carbon atom having the above in the main chain or at the end thereof.
The base rubber may contain a rubber or resin other than the ethylene-acrylic rubber and the polyolefin resin modified with the unsaturated carboxylic acid component. Such rubber or resin is not particularly limited as long as it is a polymer resin or rubber having the above-mentioned graft-reactive site in the main chain or at the end thereof.
The content of each component of this base rubber is appropriately determined so that the total of each component is 100% by mass, and is preferably selected from the following range.

-Ethylene-Acrylic rubber-
In the present invention, ethylene-acrylic rubber refers to one obtained by copolymerizing at least ethylene and an acrylic acid alkyl ester as constituent components. The ethylene-acrylic rubber preferably contains an acrylic acid alkyl ester component in an amount of 50% by mass or more. The acrylic acid alkyl ester component is preferably 60% by mass or less. Those containing methyl acrylate and / or ethyl acrylate as the monomer component are more preferable, and those containing methyl acrylate are particularly preferable.
As the ethylene-acrylic rubber, from each copolymer such as a binary copolymer of ethylene and an acrylic acid alkyl ester and a ternary copolymer obtained by copolymerizing a copolymerization component containing a carboxy group with the binary copolymer. Rubber can be used particularly preferably. Examples of such a copolymerization component containing a carboxy group include a compound having a carboxy group and an unsaturated group (usually an ethylenically unsaturated group) copolymerizable with ethylene or an acrylic acid alkyl ester. For example, (meth) acrylic acid and maleic acid can be mentioned. Examples of the ternary copolymer include an ethylene-acrylic acid alkyl ester-acrylic acid copolymer and an ethylene-acrylic acid alkyl ester-maleic acid copolymer, and in particular, an ethylene-acrylic acid alkyl ester-acrylic acid copolymer. Copolymers are preferred.
Examples of the ethylene-acrylic rubber composed of the binary copolymer include Baymac DP and Baymac DLS. Examples of the ethylene-acrylic rubber composed of the ternary copolymer include Baymac G, Baymac HG, Baymac LS, Baymac GLS, and Baymac Ultra HT-OR (trade names, all manufactured by Mitsui and DuPont Polychemical). ..
One type of ethylene-acrylic rubber may be used alone, or two or more types may be used in combination.
The Mooney viscosity of ethylene-acrylic rubber is preferably 10 to 50 (ML (1 + 4) 100 ° C.) in terms of extrusion moldability, tensile strength, wear resistance, etc., and is preferably 15 to 40 (ML (1 + 4) 100 ° C.). ° C.) is more preferred, and 18-35 (ML (1 + 4) 100 ° C.) is even more preferred.
Mooney viscosity is measured based on the measuring method specified in JIS K 630-1: 2013.
From the viewpoint of achieving both extrusion moldability and tensile strength, it is preferable to use a binary copolymer and a ternary copolymer in combination.
By containing ethylene-acrylic rubber in the base rubber used in the production method of the present invention, the appearance, flame retardancy, oil resistance and the like can be improved. Further, heat resistance can be imparted if necessary.

The content of ethylene-acrylic rubber is 55 to 95% by mass in 100% by mass of the base rubber. When the content is 55 to 95% by mass, the silane crosslinked acrylic rubber molded product can be imparted with sufficient appearance, elongation at break, oil resistance, and abrasion resistance. The content of ethylene-acrylic rubber in the base rubber is preferably 70 to 85% by mass. When the content of ethylene-acrylic rubber is within the above range, the flame retardancy or oil resistance of the silane crosslinked acrylic rubber molded product can be further improved.
When the binary copolymer and the ternary copolymer are used in combination, the content (total amount) of the ethylene-acrylic rubber satisfies the above range, and the binary copolymer weight is contained in 100% by mass of the base rubber. It is preferable that the coalescence is 25 to 45% by mass and the ternary copolymer is 20 to 60% by mass. Within the above range, the silane crosslinked acrylic rubber molded product is excellent in extrusion moldability in addition to appearance, mechanical properties, flame retardancy, oil resistance and / or wear resistance.

− Polyolefin resin modified with unsaturated carboxylic acid component −
The polyolefin resin modified with an unsaturated carboxylic acid component (hereinafter, also referred to as an unsaturated carboxylic acid-modified polyolefin resin) is not particularly limited, and a resin or the like of a (co) polymer modified with an unsaturated carboxylic acid component may be used. Can be mentioned.
By including the unsaturated carboxylic acid-modified polyolefin resin in the base rubber used in the production method of the present invention, the appearance, mechanical properties, abrasion resistance and the like can be improved.

The polyolefin resin in the unsaturated carboxylic acid-modified polyolefin resin is not particularly limited as long as it has a site capable of the grafting reaction, and is, for example, a polyethylene resin, a polypropylene resin, a polybutene resin, a polymethylpentene resin, or an ethylene-α. − An olefin copolymer resin, a polyolefin copolymer resin having an acid copolymer component or an acid ester copolymer component, and the like can be mentioned, and one kind of such polyolefin resin may be used alone, or two or more kinds thereof. May be used in combination. In the present invention, it is preferable to use a polyethylene resin, a polypropylene resin, or the like as the polyolefin resin from the viewpoint of the balance between tensile strength and elongation at break.

The polyethylene resin may be a resin of a polymer containing an ethylene component, and is a homopolymer composed only of ethylene, or a copolymer of ethylene and α-olefin (preferably 5 mol% or less) (corresponding to polypropylene). Excludes), as well as resins made of copolymers of ethylene and non-olefins (preferably 1 mol% or less) having only carbon, oxygen and hydrogen atoms as functional groups. As the above-mentioned α-olephyrene and non-olefin, known ones conventionally used as a copolymerization component of polyethylene can be used without particular limitation.
Examples of the polyethylene that can be used in the present invention include high density polyethylene (HDPE), low density polyethylene (LDPE), ultrahigh molecular weight polyethylene (UHMW-PE), linear low density polyethylene (LLDPE) or ultralow density polyethylene (VLDPE). Can be mentioned. Among them, high-density polyethylene, low-density polyethylene, and linear low-density polyethylene are preferable, and linear low-density polyethylene or low-density polyethylene is more preferable. One type of polyethylene resin may be used alone, or two or more types may be used in combination.

The polypropylene resin may be a resin of a polymer containing a propylene component as a main component, and is a resin such as a propylene homopolymer (homopolypropylene resin), an ethylene-propylene random copolymer, or an ethylene-propylene block copolymer. Can be used.
The ethylene-propylene random copolymer means that the content of the ethylene component is about 1 to 10% by mass, and the ethylene component is randomly incorporated into the propylene chain. Further, the ethylene-propylene block copolymer refers to one having an ethylene or ethylene-propylene rubber (EPR) component content of about 5 to 20% by mass, and the ethylene or EPR component is independently present in the propylene component. It is a sea-island structure. Particularly preferred as the polypropylene resin is an ethylene-propylene random copolymer resin in terms of appearance. The ethylene component content is a value measured according to the method described in ASTM D3900.
As the polypropylene resin, one type may be used alone or two or more types may be used in combination.

The ethylene-α-olefin copolymer resin preferably includes a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms (excluding those corresponding to the above-mentioned polyethylene and polypropylene). The α-olefin is not particularly limited, and examples thereof include 1-propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene or 1-dodecene. The ethylene-α-olefin copolymer may be used alone or in combination of two or more.

The acid copolymerization component or acid ester copolymerization component in the polyolefin copolymer resin having an acid copolymerization component or acid ester copolymerization component is not particularly limited, but is not particularly limited, but a carboxylic acid compound such as (meth) acrylic acid, vinyl acetate, etc. Alternatively, an acid ester compound such as an alkyl (meth) acrylate (preferably having 1 to 12 carbon atoms) can be mentioned. Examples of the polyolefin copolymer resin having an acid copolymer component or an acid ester copolymer component include an ethylene-vinyl acetate copolymer (EVA), an ethylene- (meth) acrylic acid copolymer, and an ethylene- (meth) acrylic. Examples thereof include various resins such as an acid alkyl copolymer (preferably an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-butyl acrylate copolymer).

The unsaturated carboxylic acid (including anhydride) forming the unsaturated carboxylic acid-modified polyolefin resin has an unsaturated group (usually an ethylenically unsaturated group) capable of reacting with the above-mentioned polyolefin resin (for example, radical addition reaction). Examples include carboxylic acids. The unsaturated carboxylic acid may have one carboxy group or two or more carboxy groups. For example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, and fumaric acid, and metal salts or organic salts thereof, and anhydrides such as maleic anhydride, itaconic anhydride, and fumaric acid anhydride can be used. .. One of these unsaturated carboxylic acids may be used alone, or two or more thereof may be used in combination.

Examples of the unsaturated carboxylic acid-modified polyolefin resin include those in which an unsaturated group reacts with the above-mentioned polyolefin and has a group derived from an unsaturated carboxylic acid as a side chain (pendant chain, graft chain, etc.).

The density of the unsaturated carboxylic acid-modified polyolefin resin is not particularly limited, but is preferably 0.880 to 0.950 g / cm ³ , and more preferably 0.9000 to 0.930 g / cm ³ . When the density of the unsaturated carboxylic acid-modified polyolefin resin is in the above range, excellent tensile strength and abrasion resistance can be imparted, and extrudability is excellent. The density of the unsaturated carboxylic acid-modified polyolefin resin can be measured by the method described in JIS K 7112.
The amount of modification of the unsaturated carboxylic acid-modified polyolefin resin by the unsaturated carboxylic acid is not particularly limited, but is preferably 0.01 to 10% by mass, more preferably 0.1 to 3% by mass, based on the polyolefin resin (before modification). % Is preferable. When an unsaturated carboxylic acid-modified polyolefin resin in this range is used, high strength and abrasion resistance can be sufficiently imparted to the obtained molded product, and sufficient elongation characteristics can also be imparted. Furthermore, since the load during extrusion molding can be suppressed, the extrusion moldability of the molding material is also excellent.
The melt flow rate (MFR) of an unsaturated carboxylic acid-modified polyolefin resin is measured according to JIS K 7210. When the type of polyolefin resin is polypropylene resin, it is measured at a measurement temperature of 230 ° C. and a load of 2.16 kg, and when it is a resin other than polypropylene resin such as polyethylene resin, it is measured at a measurement temperature of 190 ° C. and a load of 2.16 kg. The value of MFR is preferably 0.05 to 100 g / 10 minutes, more preferably 0.2 to 30 g / 10 minutes. When an unsaturated carboxylic acid-modified polyolefin resin having an MFR in this range is used, it is easily compatible with ethylene-acrylic rubber during kneading and has excellent dispersibility of the inorganic filler, so that high strength characteristics, abrasion resistance, and elongation characteristics can be obtained. ..

The unsaturated carboxylic acid-modified polyolefin resin may be appropriately synthesized or a commercially available product may be used. When synthesizing an unsaturated carboxylic acid-modified polyolefin resin, the polyolefin resin is usually prepared by heating and kneading the polyolefin resin and the unsaturated carboxylic acid in the presence of an organic peroxide at a temperature equal to or higher than the decomposition temperature of the organic peroxide. It can be obtained by modification (reaction with unsaturated carboxylic acid).

As the unsaturated carboxylic acid-modified polyolefin resin, one type may be used, or two or more types may be used in combination.

Commercially available unsaturated carboxylic acid-modified polyolefin resins include, for example, "Adtex" (trade name: manufactured by Japan Polyethylene Corporation), "Admer" (trade name: manufactured by Mitsui Chemicals, Inc.), "Fusabond" (trade name: manufactured by DuPont Co., Ltd.) and the like can be mentioned.

The content of the unsaturated carboxylic acid-modified polyolefin resin is 5 to 45% by mass in 100% by mass of the base rubber component. When the content is 5 to 45% by mass, a molded product having excellent appearance, wear resistance, and oil resistance can be obtained. In addition, it may be possible to obtain a molded product having excellent elongation at break. The content of the unsaturated carboxylic acid-modified polyolefin resin is preferably 15 to 30% by mass.

The total content of the ethylene-acrylic rubber and the unsaturated carboxylic acid-modified polyolefin resin in 100% by mass of the base rubber is preferably 70 to 100% by mass, more preferably 80 to 100% by mass. When it is 70 to 100% by mass, high tensile strength and oil resistance can be imparted.
The ratio of the content of ethylene-acrylic rubber to the content of unsaturated carboxylic acid-modified polyolefin resin is [content of ethylene-acrylic rubber]: [content of unsaturated carboxylic acid-modified polyolefin resin] = 18: 1-1. .375: 1 is preferable, and 17: 1-3.75: 1 is more preferable.

− Other base rubber components −
Ethylene-α-olefin copolymer resin, polyethylene resin, polypropylene resin (excluding those modified with unsaturated carboxylic acid), styrene-based elastomer, and ethylene-based resin, as long as the effects of the present invention are not impaired. Polymer rubber (excluding the above ethylene-acrylic rubber), mineral oil and the like can be used. Examples of the ethylene-α-olefin copolymer resin, polyethylene resin, and polypropylene resin include those that can be used as the polyolefin resin that forms the unsaturated carboxylic acid-modified polyolefin resin described above. As the polyethylene resin, linear low-density polyethylene is preferable. As the styrene-based elastomer, ethylene-based copolymer rubber, and mineral oil, those usually used for resin compositions or rubber compositions can be used.

When the base rubber contains other base rubber components, the content of the other base rubber components is not particularly limited as long as the amounts of the ethylene-acrylic rubber and the unsaturated carboxylic acid-modified polyolefin resin are within the above ranges, but the base rubber It is preferably 5 to 20% by mass, more preferably 7 to 15% by mass in 100% by mass.

<Organic peroxide>
Organic peroxides generate radicals at least by thermal decomposition, and as a catalyst, graft reaction by radical reaction of silane coupling agent to rubber component (grafting reaction site of silane coupling agent and rubber component) It is a covalent bond forming reaction with a reactive site, and also has a function of causing a (radical) addition reaction). In particular, when the silane coupling agent contains an ethylenically unsaturated group as a grafting reaction site, a grafting reaction by a radical reaction between the ethylenically unsaturated group and the rubber component (including a reaction of extracting hydrogen radicals from the rubber component) is carried out. It works to cause it to occur.
The organic peroxide is not particularly limited as long as it generates radicals. For example, the general formulas: R ^1- OO-R ² , R ^3- OO-C (= O) R ⁴ , R ⁵ C. The compound represented by (= O) -OO (C = O) R ⁶ is preferable. Here, R ^{1 to} R ⁶ independently represent an alkyl group, an aryl group, or an acyl group, respectively. Of R ^{1 to} R ⁶ of each compound, those which are all alkyl groups or those in which one is an alkyl group and the rest are acyl groups are preferable.

Examples of such an organic peroxide include the organic peroxide described in paragraph [0037] of International Publication No. 2015/04647, and the description thereof is referred to herein and the content thereof is described in the present specification. Import as part. Dicumyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di in terms of odor, colorability and scorch stability. -(Tert-Butylperoxy) hexyne-3 is preferred.

The decomposition temperature of the organic peroxide is preferably 120 to 195 ° C, particularly preferably 125 to 180 ° C. The decomposition temperature of the organic peroxide is equal to or lower than the melt mixing temperature in the step (a-2) described later.
In the present invention, the decomposition temperature of an organic peroxide is the temperature at which a single composition of an organic peroxide causes a decomposition reaction with two or more compounds in a certain temperature or temperature range. means. Specifically, it refers to the temperature at which heat absorption or heat generation starts when heated from room temperature at a heating rate of 5 ° C./min in a nitrogen gas atmosphere by thermal analysis such as the DSC method.

<Inorganic filler>
In the present invention, the inorganic filler is particularly limited as long as it has a site on its surface that can be chemically bonded to a reaction site such as a silanol group of a silane coupling agent by hydrogen bond or covalent bond, or by intermolecular bond. Can be used without. Examples of the site of this inorganic filler that can be chemically bonded to the reaction site of the silane coupling agent include an OH group (hydroxyl group, water molecule of water-containing or water of crystallization, OH group such as carboxy group), amino group, SH group and the like. Be done.

The inorganic filler is not particularly limited, and for example, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whisk, and the like. Examples thereof include metal hydrates such as hydrated aluminum silicate, hydrated magnesium silicate, basic magnesium carbonate, hydrotalcite, talc and other compounds having hydroxyl groups or crystalline water. In addition, boron nitride, silica (crystalline silica, amorphous silica, etc.), carbon, clay, zinc oxide, tin oxide, titanium oxide, molybdenum oxide, antimony trioxide, silicone compound, quartz, zinc borate, white carbon, Examples thereof include zinc borate, zinc hydroxytinate, and zinc tinate.

As the inorganic filler, a surface-treated inorganic filler surface-treated with a silane coupling agent or the like can be used. For example, examples of the silane coupling agent surface-treated inorganic filler include Kisuma 5L and Kisma 5P (both trade names, magnesium hydroxide, manufactured by Kyowa Chemical Industry Co., Ltd., etc.). The amount of the surface treatment of the inorganic filler with the silane coupling agent is not particularly limited, but is, for example, 3% by mass or less.
When the inorganic filler is surface-treated in advance, aggregation of the inorganic fillers is suppressed and the dispersibility of the inorganic filler is enhanced. Therefore, it is considered that the chances of cross-linking between the inorganic filler and the unsaturated carboxylic acid-modified polyolefin resin are increased, and the abrasion resistance and the like are improved.

Among these inorganic fillers, at least one selected from the group consisting of metal hydrate, talc, clay, silica and carbon black is preferable, and metal hydrate is more preferable.
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 0.2 to 10 μm, more preferably 0.3 to 8 μm, further preferably 0.4 to 5 μm, and particularly preferably 0.4 to 3 μm. preferable. When the average particle size is within the above range, the holding effect of the silane coupling agent is high and the tensile strength is excellent. Further, if necessary, the heat resistance can be made excellent. In addition, the inorganic filler is less likely to be secondarily aggregated when mixed with the silane coupling agent, resulting in an excellent appearance. The average particle size is determined by an optical particle size measuring device such as a laser diffraction / scattering type particle size distribution measuring device in which an inorganic filler is dispersed with alcohol or water.

<Silane coupling agent>
The silane coupling agent used in the present invention chemically bonds an inorganic filler with a grafting reaction site (group or atom) capable of grafting with a base rubber in the presence of radicals generated by decomposition of an organic peroxide. Any one having at least a reaction site capable of reacting with a vulnerable site and capable of silanol condensation (including a site produced by hydrolysis, for example, a mono, di or trialkoxysilyl group) may be used. Examples of such a silane coupling agent include silane coupling agents conventionally used in the silane cross-linking 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, 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 from each other.

R _a11 is a grafting reaction sites, groups containing ethylenically unsaturated groups are preferred. Examples of the group containing an ethylenically unsaturated group include a vinyl group, a (meth) acryloyloxyalkylene group, and a p-styryl group. Of these, 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 monovalent aliphatic hydrocarbon groups having 1 to 8 carbon atoms excluding the aliphatic unsaturated hydrocarbon group. R _b11 is preferably Y ¹³ described later.

Y ¹¹ , Y ¹² and Y ¹³ indicate silanol condensable reaction sites (hydrolyzable organic groups). For example, 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 can be mentioned, and an alkoxy group is preferable. Specific examples of the organic group that can be hydrolyzed include methoxy, ethoxy, butoxy, and acyloxy. Of these, 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 cup 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 allyltri. Examples thereof include vinylsilanes such as ethoxysilane and vinyltriacetoxysilane, and (meth) acryloxisilanes such as metharoxypropyltrimethoxysilane, metharoxypropyltriethoxysilane, and metharoxypropylmethyldimethoxysilane.

Among the above silane coupling agents, a silane coupling agent having a vinyl group and an alkoxy group at the ends 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 diluted with a solvent or the like.

<Silanol condensation catalyst>
The silanol condensation catalyst has a function of causing a silane coupling agent grafted on the base rubber to undergo a condensation reaction in the presence of water. Based on the action of this silanol condensation catalyst, the rubber components are crosslinked with each other via a silane coupling agent. As a result, a silane crosslinked acrylic rubber molded product having excellent tensile strength can be obtained. Further, if necessary, a silane crosslinked acrylic rubber molded product having excellent heat resistance can be obtained.

The silanol condensation catalyst is not particularly limited, and examples thereof include an organotin compound, a metallic soap, and a platinum compound. Common 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.

<Career>
The silanol condensation catalyst is used, if desired, mixed with resin or rubber. The resin or rubber (also referred to as a carrier) is not particularly limited, but the rubber and / or resin component described in the base rubber can be used. The carrier is preferably a polyethylene resin.

<Additives>
An object of the present invention is various additives generally used in electric wires, electric cables, electric cords, automobile parts, OA equipment, building parts, miscellaneous goods, sheets, foams, tubes, and pipes. It may be appropriately blended as long as the effect is not impaired. Examples of such additives include cross-linking aids, antioxidants, lubricants, metal deactivators, flame-retardant (auxiliary) agents and other resins.

A cross-linking aid is a compound that forms a partially cross-linked structure with a rubber component in the presence of an organic peroxide. For example, a polyfunctional compound and the like can be mentioned.
The antioxidant is not particularly limited, and examples thereof include an amine antioxidant, a phenol antioxidant, and a sulfur antioxidant.
Examples of the lubricant include hydrocarbons, siloxanes, fatty acids, fatty acid amides, esters, alcohols, metal soaps and the like.

<Manufacturing method of silane crosslinked acrylic rubber molded product>
Hereinafter, a method for producing the silane crosslinked acrylic rubber molded product of the present invention will be described.

Step (1): Silane coupling agent 1 having 0.01 to 0.5 parts by mass of organic peroxide, 40 to 250 parts by mass of inorganic filler, and the above-mentioned grafting reaction site with respect to 100 parts by mass of base rubber. Silane is obtained by melt-mixing ~ 15 parts by mass or less with a silanol condensation catalyst and allowing a radical generated from an organic peroxide to carry out a grafting reaction between a grafting reaction site and a site capable of a grafting reaction of the base rubber. Step of obtaining a reaction composition containing a crosslinkable rubber Step (2): Step of molding the reaction composition to obtain a molded product Step (3): Contacting the molded product with water to form a silane crosslinked acrylic rubber The process of getting a body

When this step (1) melts and mixes all of the base rubber in the following step (a-2), it has a step (a-1), a step (a-2), and a step (c). When a part of the base rubber is melt-mixed in (a-2), it has a step (a-1), a step (a-2), a step (b) and a step (c).
Step (a-1): At least a step of mixing an inorganic filler and a silane coupling agent to prepare a mixture Step (a-2): A mixture and all or a part of the base rubber in the presence of an organic peroxide. By melting and mixing at a temperature higher than the decomposition temperature of the organic peroxide and causing the grafting reaction site and the grafting reaction-capable site of the base rubber to undergo a grafting reaction with radicals generated from the organic peroxide, silane Step of preparing a silane master batch containing a crosslinkable rubber Step (b): A step of melt-mixing the rest of the base rubber and a silanol condensation catalyst to prepare a catalyst master batch Step (c): Silane master batch and silanol condensation Step of melt-mixing a catalyst or a catalyst master batch to obtain the above reaction composition Hereinafter, both steps (a-1) and (a-2) may be collectively referred to as step (a).

In the production method of the present invention, the "base rubber" is a rubber for forming a silane crosslinked acrylic rubber molded product or a silane crosslinked acrylic rubber composition. Therefore, in the production method of the present invention, it is sufficient that the reaction composition obtained in the step (1) contains 100 parts by mass of the base rubber. For example, in the step (a), "a mode in which the entire amount (100 parts by mass) of the base rubber is blended" and "a mode in which a part of the base rubber is blended" are included.

When a part of the base rubber is blended in the step (a-2), 100 parts by mass of the base rubber blended in the step (1) is the base rubber mixed in the steps (a-2) and (b). The total amount.
Here, when the balance of the base rubber is blended in the step (b), the base rubber is preferably blended in an amount of 80 to 99% by mass, more preferably 94 to 98% by mass in the step (a-2). In step (b), preferably 1 to 20% by mass, more preferably 2 to 6% by mass is blended.

In the step (1), the blending amount (content) in the base rubber of the ethylene-acrylic rubber and the polyolefin resin modified with the unsaturated carboxylic acid component is as described above.

In the step (1), the blending amount of the organic peroxide is 0.01 to 0.5 parts by mass, preferably 0.05 to 0.2 parts by mass with respect to 100 parts by mass of the base rubber. By setting the blending amount of the organic peroxide to 0.01 to 0.5 parts by mass, the grafting reaction can be carried out in an appropriate range, the condensation between the silane coupling agents can be suppressed, and the mechanical properties can be improved. In some cases, sufficient heat resistance and reinforcing properties can be obtained, and since direct cross-linking of the rubber component due to a side reaction is suppressed, a composition having an excellent appearance can be obtained without causing gel lumps. ..

The blending amount of the inorganic filler is 40 to 250 parts by mass, preferably 80 to 200 parts by mass, and more preferably 100 to 130 parts by mass with respect to 100 parts by mass of the base rubber. By setting the blending amount of the inorganic filler to 40 to 250 parts by mass, flame retardancy and mechanical properties required for the wiring material can be imparted to the silane crosslinked acrylic rubber molded product. Further, it is possible to suppress an increase in load during molding and kneading, and enable secondary molding.
From the viewpoint of imparting high tensile strength, oil resistance, abrasion resistance and flame retardancy, the polyolefin resin 15 modified with 70 to 85% by mass of ethylene-acrylic rubber and an unsaturated carboxylic acid component in 100% by mass of the base rubber. It is preferably ~ 30% by mass, and the blending amount of the inorganic filler with respect to 100 parts by mass of the base rubber is 80 to 200 parts by mass.

The blending amount of the silane coupling agent is 1 to 15 parts by mass, preferably 3 to 15 parts by mass, and more preferably 4 to 8 parts by mass with respect to 100 parts by mass of the base rubber.
When the blending amount of the silane coupling agent is 1 to 15 parts by mass, the silane coupling agent is adsorbed on the surface of the inorganic filler and the silane coupling agent can be suppressed from volatilizing during kneading, which is economical. is there. In addition, it is possible to prevent the non-adsorbed silane coupling agent from condensing and causing gels and roughness on the molded product to deteriorate the appearance. Further, if necessary, the cross-linking reaction can be sufficiently advanced to exert excellent tensile strength.

When the blending amount of the silane coupling agent exceeds 4.0 parts by mass and is 15.0 parts by mass or less, a silane crosslinked acrylic rubber molded product having more excellent oil resistance can be produced.

The blending amount of the silanol condensation catalyst is not particularly limited, and is preferably 0.0001 to 0.5 parts by mass, and more preferably 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the base rubber. When the blending amount of the silanol condensation catalyst is within the above range, the cross-linking reaction by the condensation reaction of the silane coupling agent tends to proceed almost uniformly, and the mechanical properties, appearance and physical properties of the silane-crosslinked acrylic rubber molded product are excellent and the productivity Is not impaired. In addition, heat resistance can be imparted if necessary.

The blending amount of the silanol condensation catalyst preferably satisfies the blending amount with respect to 100 parts by mass of the base rubber, but can also be specified in relation to the rubber component in the base rubber. Specifically, it is preferably 0.01 to 0. With respect to 100 parts by mass of the rubber component (the total of ethylene-acrylic rubber and the rubber component when it is contained as another rubber component) in the base rubber. It is 5 parts by mass, more preferably 0.03 to 0.3 parts by mass, and further preferably 0.05 to 0.2 parts by mass. By adjusting to this blending amount, it is possible to suppress the generation of gel lumps during molding, and the cross-linking proceeds sufficiently, and the mechanical strength and, in some cases, the heat resistance are excellent.

In the silane masterbatch, all or part of the base rubber, the organic peroxide, the inorganic filler, and the silane coupling agent are charged into the mixer in the above-mentioned amounts, and the temperature exceeds the decomposition temperature of the organic peroxide. By the step (a) of melt-kneading while heating to the temperature of (a), the above-mentioned grafting reaction can be caused to prepare.
In the present invention, "melting and mixing all or part of the base rubber, organic peroxide, inorganic filler and silane coupling agent" does not specify the mixing order at the time of melting and mixing. It means that they may be mixed in order. That is, the mixing order in the step (a) is not particularly limited.
Further, the method of mixing the base rubber is not particularly limited. For example, a base rubber prepared by mixing in advance may be used, or each component, for example, each rubber component may be mixed separately.

In the present invention, preferably, the silane coupling agent is not introduced alone into the silane masterbatch, but is premixed with an inorganic filler or the like. That is, at least an inorganic filler and a silane coupling agent are mixed to prepare a mixture (step (a-1)). It is considered that 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. This makes it possible to reduce the volatilization of the silane coupling agent during the subsequent melt mixing. Further, it is possible to prevent the silane coupling agent that does not adsorb or bond with the inorganic filler from condensing and making melt kneading difficult. Furthermore, a desired shape can be obtained during extrusion molding.

As such a mixing method, the organic peroxide, the inorganic filler, and the silane coupling agent are preferably mixed at a temperature lower than the decomposition temperature of the organic peroxide, preferably room temperature (25 ° C.), for about several minutes to several hours. A method of melt-mixing the obtained mixture and the base rubber after mixing (dispersing) by a dry method or a wet method can be mentioned (step (a)). By this melt mixing, radicals generated from the organic peroxide cause a grafting reaction between the grafting reaction site of the silane coupling agent and the grafting reaction site of the base rubber. As a result, a silane crosslinkable rubber (silane graft polymer) in which the silane coupling agent is covalently bonded to the rubber component is synthesized, and a silane master batch containing the silane crosslinkable rubber is prepared. In this grafting reaction, one molecule of silane coupling agent is usually added to one grafting reaction-capable site, but the present invention is not limited thereto.
The melt mixing is preferably performed in a mixer-type kneader such as a Banbury mixer or a kneader. By doing so, it is possible to prevent an excessive cross-linking reaction between the rubber components, and the appearance is excellent.
In mixing at a temperature lower than the decomposition temperature of the organic peroxide, the base rubber may be present as long as the temperature lower than the decomposition temperature is maintained. In this case, it is preferable to mix the inorganic filler and the silane coupling agent together with the base rubber at the above temperature (step (a-1)), and then melt-mix them. That is, the radical grafting reaction between the base rubber and the silane coupling agent is suppressed to prepare a mixture thereof (for example, a dry blend), and then the obtained mixture is further melt-mixed to obtain the above-mentioned grafting reaction. It is preferable to cause. In the present invention, each of the above components can be melt-mixed at once. In this case, part or all of the silane coupling agent is adsorbed or bonded to the inorganic filler during melt mixing.

The method of mixing the inorganic filler and the silane coupling agent is not particularly limited, and the organic peroxide may be mixed at the same time as the inorganic filler or the like, or in any of the mixing steps of the inorganic filler and the silane coupling agent. It 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. In the present invention, the organic peroxide and the silane coupling agent should be mixed substantially together. On the other hand, 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.
Further, the organic peroxide may be a mixture with other components or may be a simple substance.

Examples of the method for mixing the inorganic filler, the silane coupling agent, and the organic peroxide include a mixing method such as a wet treatment and a dry treatment. Specific examples thereof include a wet treatment in which a silane coupling agent is added in a solvent such as alcohol or water in which an inorganic filler is dispersed, a dry treatment in which both are added and mixed with or without heating, and both. In the present invention, a dry treatment in which a silane coupling agent is added to an inorganic filler, preferably a dried inorganic filler, with or without heating and mixed is preferable.
In the wet mixing, the bond between the silane coupling agent and the inorganic filler becomes strong, so that the volatilization of the silane coupling agent can be effectively suppressed, but the silanol condensation reaction may not proceed easily. On the other hand, in the dry mixing, the silane coupling agent easily volatilizes, but the binding force between the inorganic filler and the silane coupling agent becomes relatively weak, so that the silanol condensation reaction easily proceeds efficiently.

In the production method of the present invention, the obtained mixture, all or part of the base rubber, and the remaining components not mixed in the step (a-1) are then organically prepared in the presence of an organic peroxide. Melt and knead while heating above the decomposition temperature of the peroxide (step (a-2)). As a result, the grafting reaction of the silane coupling agent to the base rubber is caused to prepare a silane masterbatch containing the silane crosslinkable rubber.

In the step (a-2), the temperature at which the above components are melt-mixed (also referred to as melt-kneading or kneading) is equal to or higher than the decomposition temperature of the organic peroxide, preferably the decomposition temperature of the organic peroxide + (25 to 110). At a temperature of ° C, more preferably 150-230 ° C. This decomposition temperature is preferably set after the rubber component has melted. At the above mixing temperature, the above components are melted, the organic peroxide is decomposed and acts, and the necessary silane grafting reaction proceeds sufficiently in the step (a-2). Other conditions, such as 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 depending on, for example, the blending amount of the inorganic filler. As the kneading 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 rubber component and the stability of the cross-linking reaction, a closed mixer such as a Banbury mixer or various kneaders is preferable.
In addition, when such an inorganic filler is usually mixed in an amount of more than 100 parts by mass with respect to 100 parts by mass of the base rubber, it is preferable to knead it with a continuous kneader, a pressure kneader, or a Banbury mixer.

In the step (a-1) and the step (a-2), particularly the step (a-2), it is preferable to knead each of the above-mentioned components without substantially mixing the silanol condensation catalyst. This makes it possible to suppress the condensation reaction of the silane coupling agent, facilitate melt-mixing, and obtain a desired shape during extrusion molding. Here, "substantially not mixed" does not exclude the silanol condensation catalyst that is inevitably present, and exists to the extent that the above-mentioned problem due to silanol condensation of the silane coupling agent does not occur. It means that it is also 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 with respect to 100 parts by mass of the base rubber.

In the step (1), the blending amounts of the other base rubber components and the additives that can be used in addition to the above components are appropriately set as long as the object of the present invention is not impaired.
In step (1), the additives, particularly antioxidants and metal deactivators, may be mixed in any step or with the components, but are preferably mixed with the carrier.
It is preferable that the cross-linking aid is not substantially mixed in the step (1), particularly in the steps (a-1) and (a-2). If the cross-linking aid is not substantially mixed, cross-linking between the rubber components is unlikely to occur during melt mixing, and the appearance of the silane-cross-linked acrylic rubber molded product is excellent. Here, "substantially not mixed" means that the cross-linking aid is not positively mixed, and does not exclude unavoidable mixing.

In this way, the step (a) consisting of the step (a-1) and the step (a-2) is performed to graft the silane coupling agent and the base rubber into a silane masterbatch (also referred to as silane MB). ) Is prepared. The silane MB thus obtained is preferably used in the production of the reaction composition (silane crosslinkable acrylic rubber composition) prepared in the step (1), preferably together with a silanol condensation catalyst or a catalyst master batch described later, as described later. Used. Silane MB is a mixture containing a silane crosslinkable rubber in which a silane coupling agent is grafted to a rubber component to the extent that it can be molded by the step (2) described later.

In the production method of the present invention, when a part of the base rubber is then melt-mixed in the step (a-2), the rest of the base rubber and the silanol condensation catalyst are melt-mixed to form a catalyst master batch (catalyst MB). The step (b) for preparing (also referred to as) is performed. Therefore, when the entire base rubber is melt-mixed in the step (a-2), the step (b) may not be performed, or another base rubber component may be mixed with the silanol condensation catalyst.

The mixing ratio of the base rubber as a carrier and the silanol condensation catalyst is not particularly limited, but is preferably set so as to satisfy the above-mentioned blending amount in the step (1).
The mixing may be any method as long as it can be mixed uniformly, and examples thereof include mixing performed under melting of the base rubber (melt mixing). The melt mixing can be performed in the same manner as the melt mixing in the above step (a-2). For example, the mixing temperature can be preferably 120 to 200 ° C, more preferably 140 to 180 ° C. Other conditions, such as the mixing time, can be set as appropriate.

In step (b), another resin can be used as a carrier in place of or in addition to the rest of the base rubber. That is, in the step (b), the rest of the base rubber when a part of the base rubber is melt-mixed in the step (a-2), or a resin other than the rubber component used in the step (a-2), and silanol. A catalyst masterbatch may be prepared by melt-mixing with a condensation catalyst.
When the carrier is another resin, the grafting reaction can be promoted in the step (a-2), and lumps are less likely to occur during molding. Therefore, the amount of the other resin blended is 100 parts by mass of the base rubber. On the other hand, it is preferably 1 to 60 parts by mass, more preferably 2 to 50 parts by mass, and further preferably 3 to 40 parts by mass.

In addition, an inorganic filler may be used in the step (b). In this case, the blending amount of the inorganic filler is not particularly limited, but is preferably 350 parts by mass or less with respect to 100 parts by mass of the carrier. By setting the amount of the inorganic filler to 350 parts by mass or less, the silanol condensation catalyst is appropriately dispersed and cross-linking easily proceeds. Further, if necessary, sufficient heat resistance can be obtained.

The catalyst MB thus prepared is a (melted) mixture of silanol condensation catalyst and carrier, optionally added filler.
This catalyst MB, together with the silane MB, is used as a masterbatch set in the production of the silane crosslinkable acrylic rubber composition prepared in the step (1).

In the production method of the present invention, the step (c) of mixing the silane MB with the silanol condensation catalyst or the catalyst MB to obtain a reaction composition is then carried out. This reaction composition is a composition containing a silane crosslinkable rubber synthesized in the above step (a-2).
The mixing method may be any mixing method as long as a uniform reaction composition can be obtained as described above.

The mixing is basically the same as the melt mixing in step (a-2). There are rubber components whose melting point cannot be measured by DSC or the like, such as elastomers, but kneading is performed at a temperature at which at least one of the rubber components and the organic peroxide melts. The melting temperature is appropriately selected according to the melting temperature of the base rubber or the carrier, and is, for example, preferably 80 to 250 ° C., more preferably 100 to 240 ° C. Other conditions, such as mixing (kneading) time, can be set as appropriate.

In the step (c), in order to avoid the silanol condensation reaction, it is preferable that the silane MB and the silanol condensation catalyst are not kept in a high temperature state for a long time in a mixed state.

This step (c) may be any step as long as the silane master batch and the silanol condensation catalyst are mixed to obtain the above reaction composition as a melt mixture thereof, and the catalyst master batch containing the silanol condensation catalyst and the carrier and silane may be used. The step of melting and mixing with the master batch is preferable.

In this way, steps (a) to (c) (step (1)) are carried out to produce a silane crosslinkable acrylic rubber composition as a reaction composition. This silane crosslinkable acrylic rubber composition contains a silane crosslinkable rubber having a different crosslinking method. In this silane crosslinkable rubber, the reaction site capable of silanol condensation 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 rubber is a crosslinkable rubber in which a silane coupling agent bonded or adsorbed to an inorganic filler is grafted to the base rubber, and a silane coupling agent not bonded or adsorbed to the inorganic filler is grafted to the base rubber. Includes at least crosslinkable rubber. Further, the silane crosslinkable rubber may have a silane coupling agent to which the inorganic filler is bonded or adsorbed, and a silane coupling agent to which the inorganic filler is not bonded or adsorbed. Further, it may contain an unreacted rubber component with the silane coupling agent.
As described above, the silane crosslinkable rubber is an uncrosslinked body in which the silane coupling agent is not silanol-condensed. In practice, when melt-mixed in step (c), partial cross-linking (partial cross-linking) is unavoidable, but the obtained silane cross-linkable acrylic rubber composition is molded at least in molding in step (2). It is assumed that the sex is retained.

In step (1), steps (a) to (c) can be performed simultaneously or continuously.

The method for producing a silane crosslinked acrylic rubber molded product of the present invention is then carried out in steps (2) and (3).
In the method for producing a silane crosslinked acrylic rubber molded product of the present invention, the step (2) of molding the obtained reaction composition to obtain a molded product is performed. In this step (2), it suffices if the reaction composition can be molded, and the molding method and molding conditions are appropriately selected according to the form of the oil-resistant product of the present invention. Examples of the molding method include extrusion molding using an extruder, extrusion molding using an injection molding machine, and molding using another molding machine. Extrusion molding is preferred when the oil resistant product of the present invention is an electric wire or an optical fiber cable.
When the step (2) is carried out by extrusion molding, the molding speed (extrusion speed) is not particularly limited and can be usually set to a linear speed of less than 10 to 250 m / min, preferably 20 to 100 m / min.
In a preferred embodiment of the above manufacturing method, extrusion molding can be set to a speed lower than the linear speed normally set. The low linear velocity is effective when forming a wiring material having a reduced diameter. For example, the linear speed can be set to less than 0.5 to 10 m / min, preferably 2 to 8 m / min.

Further, the step (2) can be performed at the same time as or continuously of the step (c). That is, as one embodiment of the melt mixing of the step (c), there is an embodiment in which the molding raw materials are melt-mixed at the time of melt molding, for example, at the time of extrusion molding, or immediately before that. For example, pellets such as dry blend may be mixed at room temperature or high temperature and introduced into a molding machine (melt mixing), or after mixing, melt mixing is performed, pelletization is performed again, and the pellet is introduced into a molding machine. May be good. More specifically, a molding material composed of a silane MB and a silanol condensation catalyst or a catalyst MB is melt-kneaded in a coating device, and then extruded and coated on an outer peripheral surface of a conductor or the like to form a desired shape. The process can be adopted.
In this way, a molded product of the silane crosslinkable acrylic rubber composition is obtained. Similar to the silane crosslinkable acrylic rubber composition, this molded product is partially crosslinked, but is in a partially crosslinked state that retains moldability in the step (2). Therefore, the silane crosslinked acrylic rubber molded article of the present invention can be crosslinked or finally crosslinked by carrying out step (3).

In the method for producing a silane crosslinked acrylic rubber molded product of the present invention, the step (3) of bringing the molded product obtained in the step (2) into contact with water is performed. As a result, the reaction site of the silane coupling agent capable of condensing silanol is hydrolyzed to silanol, and the hydroxylanol condensation catalyst present in the molded product condenses the hydroxyl groups of silanol to cause a cross-linking reaction. In this way, a silane-crosslinked acrylic rubber molded product obtained by cross-linking the silane coupling agent with silanol condensation can be obtained.
The process itself of this step (3) can be performed by a usual method. Condensation between silane coupling agents proceeds only by storing at room temperature. Therefore, in step (3), it is not necessary to positively bring the molded product into contact with water. In order to promote this cross-linking reaction, the molded product can also be brought into contact with water. For example, a method of actively contacting with water such as immersion in hot water, charging into a moist heat tank, and exposure to high-temperature steam can be adopted. Further, at that time, pressure may be applied to allow water to permeate into the inside.

In this way, the method for producing a silane crosslinked acrylic rubber molded product of the present invention is carried out, and a silane crosslinked acrylic rubber molded product is produced from the silane crosslinked acrylic rubber composition of the present invention. As will be described later, this silane crosslinked acrylic rubber molded body contains a crosslinked rubber in which a silane crosslinkable rubber is condensed via a siloxane bond. One form of this silane crosslinked acrylic rubber molded product contains a silane crosslinked rubber and an inorganic filler. Here, the inorganic filler may be bonded to the silane coupling agent of the silane crosslinked rubber. Therefore, this silane crosslinked rubber is a crosslinked rubber in which a plurality of crosslinked rubbers are bonded or adsorbed to an inorganic filler by a silane coupling agent and bonded (crosslinked) via the inorganic filler and the silane coupling agent, and the above-mentioned crosslinkable rubber. The reaction site of the silane coupling agent is hydrolyzed and undergoes a silanol condensation reaction with each other, thereby containing at least a crosslinked rubber crosslinked via the silane coupling agent. Further, the silane crosslinked rubber may be a mixture of bonding (crosslinking) via an inorganic filler and a silane coupling agent and crosslinking via a silane coupling agent. Further, it may contain a rubber component that has not reacted with the silane coupling agent and / or a silane crosslinkable rubber that has not been crosslinked.

The details of the reaction mechanism in the production method of the present invention have not been clarified yet, but it is considered as follows. That is, when the rubber component is heated and kneaded together with the inorganic filler and the 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, the organic peroxide decomposes to generate radicals and becomes a rubber component. On the other hand, grafting of the silane coupling agent occurs.

The heating in step (a-2) also partially causes a reaction of forming a chemical bond by a covalent bond between the silane coupling agent and a group such as a hydroxyl group on the surface of the inorganic filler.
In the present invention, the final cross-linking reaction may be carried out in the step (3), and if a specific amount of the silane coupling agent is added to the base rubber as described above, the processability at the time of molding (extrusion moldability is impaired). It is possible to blend a large amount of inorganic filler without any problem, and it is possible to have heat resistance, mechanical properties, etc. while ensuring flame retardancy.

The mechanism of action of the above process of the present invention is not yet clear, but is presumed as follows. That is, by using an inorganic filler and a silane coupling agent before and / or during kneading with the base rubber, the silane coupling agent can be combined with the inorganic filler via a group capable of chemically bonding to the reaction site. It binds and is retained by binding to the uncrosslinked portion of the rubber component (the site where the grafting reaction is possible) with a group capable of grafting reaction, which is present at the other end. Alternatively, it is physically or chemically adsorbed and retained in the holes or surfaces of the inorganic filler without binding to the inorganic filler. In this way, a silane coupling agent that binds to the inorganic filler with a strong bond (for example, the formation of a chemical bond with a hydroxyl group on the surface of the inorganic filler is considered) and a silane coupling agent that binds to the inorganic filler with a weak bond (the reason is considered). The reason may be, for example, an interaction due to hydrogen bonds, an interaction between ions, partial charges or dipoles, an action due to adsorption, etc.). In this state, when organic peroxide is added and kneaded, the silane coupling agent hardly volatilizes as described later, and the silane coupling agent having a different bond with the inorganic filler reacts with the rubber component by grafting. A silane crosslinkable rubber is formed.

By the above-mentioned 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 the group capable of the grafting reaction, which is a cross-linking group, is a rubber component. It reacts with the cross-linking site by grafting. 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 rubber components are bonded via the inorganic filler particles. These reactions or bonds expand the cross-linking network through this inorganic filler. That is, a silane crosslinkable rubber formed by a silane coupling agent bonded to an inorganic filler reacting with a rubber component by grafting is formed.

In the case of a silane coupling agent having a strong bond with the inorganic filler, the condensation reaction with the silanol condensation catalyst in the presence of water is unlikely to occur, and the bond with the inorganic filler is maintained. It is considered that the reason why the silanol condensation reaction is unlikely to occur is that the binding energy between the inorganic filler and the silane coupling agent is very high, and the condensation reaction does not occur even under the silanol condensation catalyst. In this way, the rubber component and the inorganic filler are bonded, and the rubber component is crosslinked via the silane coupling agent. As a result, the adhesion between the rubber component and the inorganic filler is strengthened, the mechanical strength and wear resistance are good, and a molded product that is not easily scratched can be 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 to the inorganic filler with a strong bond is considered to contribute to high mechanical properties, wear resistance, and in some cases, scratch 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, and the radical that can undergo a grafting reaction, which is a cross-linking group of the silane coupling agent, is organic peroxide. A grafting reaction occurs by reacting with radicals of rubber components generated by extraction of hydrogen radicals by radicals generated by decomposition of an object. That is, a silane crosslinkable rubber is formed in which the silane coupling agent separated from the inorganic filler is grafted onto the rubber component. The silane coupling agent of the graft portion thus produced is subsequently mixed with a silanol condensation catalyst and brought into contact with water to cause a condensation reaction (crosslinking reaction). The heat resistance of the silane-crosslinked acrylic rubber molded product obtained by this cross-linking reaction becomes high, and it becomes possible to obtain a silane-crosslinked acrylic rubber molded product that does not melt even at a high temperature. As described above, the silane coupling agent bonded to the inorganic filler with a weak bond is considered to contribute to the improvement of the degree of cross-linking, that is, the improvement of heat resistance.

In particular, in the present invention, the cross-linking reaction by condensation using a silanol condensation catalyst in the presence of water in step (3) is performed after forming the molded product. As a result, as compared with the conventional method of forming a molded body after the final cross-linking reaction, workability in the process up to forming the molded body is excellent, and it is possible to obtain higher heat resistance than before.

Further, when the silane coupling agent is mixed with the inorganic filler 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. Moreover, in the present invention, when a silane coupling agent of more than 4.0 parts by mass and 15.0 parts by mass or less is mixed with the inorganic filler, as described above, the step (1), particularly the step (a-). The cross-linking reaction between the rubber components during the melt-kneading in 2) can be effectively suppressed. In addition, the silane coupling agent is bound to the inorganic filler, and is less likely to volatilize during melt-kneading in the step (1), especially in the step (a-2), and the reaction between the liberated silane coupling agents also occurs. It can be effectively suppressed.

The production method of the present invention can impart excellent oil resistance and wear resistance to a silane crosslinked acrylic rubber molded product while maintaining mechanical properties and flame retardancy.
The details of the ability to impart such excellent properties to the silane-crosslinked acrylic rubber molded product are not yet clear, but it is considered that the base rubber component and the inorganic filler cooperate to act as follows.
The reason why the silane crosslinked acrylic rubber molded product can be imparted with mechanical properties and flame retardancy is that a base rubber containing a specific amount of ethylene-acrylic rubber and an unsaturated carboxylic acid-modified polyolefin resin is used, and a specific amount of an inorganic filler is blended. , It is probable that the silane cross-linking was performed.
The unsaturated carboxylic acid-modified polyolefin resin contained in the base rubber binds or adsorbs (chemically or physically interacts) with the inorganic filler via the carboxylic acid group introduced by the modification. Therefore, in the present invention, in addition to the above-mentioned cross-linking by the strong bond and the weak bond between the silane coupling agent and the inorganic filler, the cross-linking (bonding) between the inorganic filler and the unsaturated carboxylic acid-modified polyolefin is also formed. .. As a result, the degree of adhesion between the inorganic filler and the base rubber component is increased. In addition, the unsaturated carboxylic acid-modified polyolefin enhances the dispersibility of the inorganic filler. As a result, it is considered that excellent wear resistance can be obtained. In addition, sufficient elongation at break (flexibility) can be maintained as a wiring material.
Further, although ethylene-acrylic rubber is non-crystalline at high temperature, it is hard to melt and has high polarity. In addition to this, since unsaturated carboxylic acid-modified polyolefin is used, the degree of adhesion between the inorganic filler and the base rubber component is high as described above. By using an ethylene-acrylic rubber having such characteristics and physical properties and an unsaturated carboxylic acid-modified polyolefin resin in a specific ratio, it becomes difficult for oil to penetrate into the silane crosslinked acrylic rubber molded body, and high oil resistance can be obtained. It is thought that it can be done.

The manufacturing method of the present invention includes products that require oil resistance (including semi-finished products, parts, and members), products that require strength in addition to oil resistance, products that require flame retardancy, rubber materials, and the like. It can be applied to the manufacture of a component of a product of the above or a member thereof. Therefore, the oil-resistant product of the present invention is such a product. At this time, the oil-resistant product of the present invention may be a product containing a silane-crosslinked acrylic rubber molded product, or a product consisting of only a silane-crosslinked acrylic rubber molded product.
Examples of the oil-resistant product of the present invention include electric wires such as flame-retardant insulated wires, coating materials for flame-retardant cables, rubber substitute electric wires / cable materials, other flame-retardant electric wire parts, flame-retardant heat-resistant sheets, flame-retardant films, and the like. Can be mentioned. In addition, power plugs, connectors, sleeves, boxes, tape base materials, tubes, seats, packings, cushioning materials, earthquake-proof materials, wiring materials used for internal and external wiring of electrical and electronic equipment, especially electric wires and optical cables. Be done.

Among the above oil-resistant products, the production method of the present invention is particularly preferably applied to the production of electric wires and optical cables, and these coating materials (insulators, sheaths) can be formed.

When the oil-resistant product of the present invention is an extruded product such as an electric wire or a cable, preferably, the molding material is melt-kneaded in an extruder (extrusion coating device) and subjected to the above-mentioned grafting reaction to cause a silane crosslinkable acrylic rubber. While preparing the composition, the silane crosslinkable acrylic rubber composition can be produced by extruding the silane crosslinkable acrylic rubber composition to the outer periphery of the conductor or the like and coating the conductor or the like (steps (c) and (2)). The temperature of the extruder at this time is preferably about 120 to 180 ° C. for the cylinder part and about 160 to 210 ° C. for the crosshead part, although it depends on various conditions of the rubber type, the take-up speed of the conductor and the like. .. In such an oil-resistant product, a silane crosslinkable acrylic rubber composition to which a large amount of inorganic filler is added is applied around the conductor by using a general-purpose extrusion coating device without using a special machine such as an electron beam crosslinker. Or, it can be formed by extruding and coating around a conductor in which tensile strength fibers are vertically attached or twisted. For example, as the conductor, a single wire such as annealed copper, a copper alloy, or aluminum, or a stranded wire can be used. Further, as the conductor, in addition to the bare wire, a conductor plated with tin or having an enamel-coated insulating layer can also be used. The wall thickness of the insulating layer (coating layer made of the silane crosslinkable acrylic rubber composition of the present invention) formed around the conductor is not particularly limited, but is usually about 0.15 to 5 mm.

The silane crosslinked acrylic rubber molded product of the present invention is effective in a portion where oil resistance, particularly high temperature oil resistance, is required. For example, not only a covering material for flame-retardant electric wires / cables, but also hoses, tubes, and rubber. It can be used as a replacement for acrylic rubber materials such as molding materials that have conventionally undergone cross-linking or chemical vulcanization steps by electron beam irradiation. Further, it is particularly effective for members requiring wear resistance, and can be used, for example, for electric wires for vehicles and electric wires for automobiles.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.
In Table 1, the numerical values relating to the blending amount of each example represent parts by mass unless otherwise specified. Further, the blanks for each component mean that the blending amount of the corresponding component is 0 parts by mass.

(Examples 1 to 16, Comparative Examples 1 to 8 and 10)
In Examples 1 to 16 and Comparative Examples 1 to 8 and 10, a part (PE) of the rubber component constituting the base rubber was used as a carrier of the catalyst MB.

First, the organic peroxide, the inorganic filler, the silane coupling agent and the antioxidant were put into a 10L Henschel mixer manufactured by Toyo Seiki in the mass ratio shown in Table 1 and mixed at room temperature (25 ° C.) for 10 minutes. A powder mixture was obtained (step (a-1)). Next, the powder mixture thus obtained and the components shown in the base rubber column of Table 1 were put into a 2L Banbury mixer manufactured by Nippon Roll in the mass ratio shown in Table 1 to carry an organic peroxide. After kneading at a temperature equal to or higher than the decomposition temperature of No. 1, specifically 190 ° C. for 10 minutes, the mixture was discharged at a material discharge temperature of 190 to 210 ° C. to obtain silane MB (step (a-2)). The silane MB thus obtained contains a silane crosslinkable rubber in which a silane coupling agent is grafted into a rubber component.

On the other hand, the carrier, the silanol condensation catalyst, and the antioxidant are melt-mixed with a Banbury mixer at a mass ratio shown in Table 1 at 180 to 190 ° C. and discharged at a material discharge temperature of 180 to 190 ° C. to obtain a catalyst MB. Obtained (step (b)). This catalyst MB is a melt mixture of carriers and silanol condensation catalysts.

Next, the silane MB and the catalyst MB were put into a closed ribbon blender and dry-blended at room temperature (25 ° C.) for 5 minutes to obtain a dry blend. At this time, the mixing ratio of the silane MB and the catalyst MB is the mass ratio shown in Table 1. Specifically, in Examples 1 to 15 and Comparative Examples 1 to 8, the ratio was such that the base rubber of the silane MB was 95 parts by mass and the carrier of the catalyst MB was 5 parts by mass. In Example 16, the base rubber of the silane MB was 80 parts by mass, and the carrier of the catalyst MB was 20 parts by mass.

Next, with a 25 mmφ extruder (L / D = 25), the die temperature was set to 200 ° C., and then to the feeder side, the extrusion temperature conditions were set to C3 = 180 ° C., C2 = 150 ° C., and C1 = 130 ° C. The prepared dry blend is put into this extruder and melt-mixed (step (c)) to obtain an outer diameter of 2.4 mmφ and an insulation thickness of 0.8 mm on a 0.8 mmφ conductor made of bare annealed copper wire. As described above, a coated conductor was obtained by extrusion and coating at a linear speed of 7 m / min (condition of appearance test (1)) or a linear speed of 20 m / min (condition of appearance test (2)).
As described above, the dry blend was melt-mixed in the extruder before extrusion molding (step (c)) to prepare a silane crosslinkable acrylic rubber composition as a reaction composition. This silane crosslinkable acrylic rubber composition is a melt mixture of silane MB and catalyst MB, and contains the above-mentioned silane crosslinkable rubber.

The obtained coated conductor was allowed to stand at room temperature (23 ° C., 50% RH) for 24 hours to hydrolyze the reaction site (trialkoxysilyl group) of the silane coupling agent, and then undergo a silanol condensation reaction (silane cross-linking). (Step (3)). In this way, each electric wire in which the conductor was coated with a silane crosslinked acrylic rubber molded body was manufactured according to the extrusion molding conditions (1) and (2). The silane-crosslinked acrylic rubber molded product as a coating has the above-mentioned silane-crosslinked acrylic rubber.

(Comparative Example 9)
An electric wire was manufactured in the same manner as in Example 1 except that the components described in the silane MB column and the catalyst MB column were melt-mixed using a 2 L Banbury mixer at the mass ratio shown in Table 1 and charged into the extruder. did.

The following components were used as the components shown in Table 1.
(1) Ethylene-acrylic rubber 1: Baymac DP (trade name, binary copolymer, manufactured by DuPont, methyl acrylate component: 65% by mass, Mooney viscosity (ML (1 + 4) 100 ° C.) = 22)
(2) Ethylene-acrylic rubber 2: Baymac Ultra HT-OR (trade name, ternary copolymer, manufactured by DuPont, methyl acrylate component: 65% by mass, carboxy group-containing copolymer component, Mooney viscosity (ML (ML) 1 + 4) 100 ° C) = 35)
(3) Ethylene-propylene-diene rubber (EPDM): Nodel 3720P (trade name, manufactured by Dow Chemical Co., Ltd.)
(4) EEA: NUC-6070 (trade name, ethylene ethyl acrylate copolymer, manufactured by Nippon Unicar Co., Ltd., ethyl acrylate component: 25% by mass, MFR (190 ° C., 2.16 kg) = 250 g / 10 minutes)
(5) PE resin: Novatec LL (trade name, linear low-density polyethylene, UE320 grade, manufactured by Japan Polyethylene Corporation)
(6) PP resin: PB222A (trade name, random polypropylene, manufactured by SunAllomer Ltd., MFR (230 ° C., 2.16 kg) = 0.8 g / 10 minutes)
(7) Modified PO1: Fusabond E226Y (trade name, unsaturated carboxylic acid (maleic acid) modified polyethylene, manufactured by DuPont, density 0.930 g / cm ³ , MFR (190 ° C, 2.16 kg) = 1.8 g / 10 Minutes)
(8) Modified PO2: Admer QE800 (trade name, unsaturated carboxylic acid (maleic acid) modified polypropylene resin, density 0.910 / cm ³ , manufactured by Mitsui Chemicals, Inc., MFR (230 ° C, 2.16 kg) = 20 g / 10 Minutes)
(9) Modified PO3: Fusabond C250 (trade name, unsaturated carboxylic acid (maleic acid) modified ethylene-vinyl acetate copolymer, manufactured by DuPont, density 0.960 g / cm ³ , MFR (190 ° C., 2.16 kg)) = 1.5 g / 10 minutes, vinyl acetate content 28%)
(10) Inorganic filler 1: Kisuma 5L (trade name, magnesium hydroxide, manufactured by Kyowa Chemical Industry Co., Ltd.)
(11) Inorganic filler 2: Heidilite H42M (trade name, aluminum hydroxide, manufactured by Showa Denko KK)
(12) Silane coupling agent: KBM-1003 (trade name, vinyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.)
(13) Organic Peroxide: Perhexa 25B (trade name, Dicumyl Peroxide, manufactured by NOF CORPORATION, decomposition temperature 179 ° C)
(14) Antioxidant: Irganox 1076 (trade name, 3- (3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate, manufactured by BASF)
(15) Silanol condensation catalyst: ADEKA STUB OT-1 (trade name, dioctyltin dilaurate, manufactured by ADEKA)

The following tests were performed on each of the manufactured electric wires, and the results are shown in Table 1.

1. 1. Appearance test (1)
When manufacturing an electric wire by extrusion molding at a linear speed of 7 m / min, if the surface of the electric wire is clean and no gel lumps are observed and the appearance is excellent, "A (advanced one)", and gel lumps are per 1 m on the wire surface. "B (good)" is when 1 to 5 pieces are seen but there is no problem with the appearance as an electric wire, and "C (C (good)" is when a lot of gels and roughness are seen on the surface of the electric wire and the appearance of the electric wire is bad. Fail) ”. A passing level of this test is that the evaluation is "B" or higher.

2. Appearance test (2)
When manufacturing an electric wire by extrusion molding at a linear speed of 20 m / min, if the surface of the electric wire is clean and no gel lumps are observed and the appearance is excellent, "A (advanced one)", and the gel lumps on the wire surface per 1 m. "B (good)" is when 1 to 5 pieces are seen but there is no problem in the appearance as an electric wire, and "C (C)" is when a lot of gels and roughness are seen on the surface of the electric wire and the appearance of the electric wire is bad. Fail) ”. A passing level of this test is that the evaluation is "B" or higher.

3. 3. Mechanical Properties A tensile test was performed on the coating (tubular piece) extracted from each electric wire manufactured using the coated conductor obtained under the condition of the above appearance test (1).
In this tensile test, the tensile strength (MPa) and the elongation at break (%) were measured under the conditions of a distance between marked lines of 25 mm and a tensile speed of 200 mm / min according to JIS C 3005.
Tensile strength of 8 MPa or more is represented by "A" as an excellent level, and those of 6 MPa or more and less than 8 MPa are represented by "B" as a passing level of this test, and those of less than 6 MPa. The fail level of the test is represented by "C".
The elongation at break was 125% or more as an excellent level, represented by "A", and 100% or more and less than 125% was represented by "B" as a passing level of this test, and was less than 100%. These are indicated by "C" as the failure level of this test.

4. Oxygen index (flame retardant)
The level of flame retardancy was measured with an oxygen index according to JIS K 7201. As the test piece, a press sheet formed to a thickness of 3 mm was used. The press sheet was prepared by melting and mixing the silane MB and the catalyst MB prepared in the same manner as in each Example and Comparative Example at 160 to 200 ° C. using an 8-inch roll, and then quickly using a press machine preheated and kept warm at 170 ° C. Was pressed at 170 ° C. for 5 minutes and left at room temperature (23 ° C., 50% RH) for 24 hours to allow silane cross-linking to proceed.
The oxygen index was 30 or more and was represented by "A" as an excellent level, and 27 or more and less than 30 was represented by "B" as a preferable level in this test and was 24 or more and less than 27. Was represented by "C" as the pass level of this test, and those below 24 were represented by "D" as the fail level of this test.

5. Oil resistance test (A)
The "oil resistance test" described in JIS C 3005 was performed on each electric wire manufactured by using the coated conductor obtained under the condition of the appearance test (1). In the oil resistance test (A), the oil immersion temperature was 100 ° C., the oil immersion time was 24 hours, and IRM903 was used as the oil.
In the evaluation of this test, the residual ratio of tensile strength and the residual ratio of elongation at break before and after the oil resistance test are both 60% or more, which is indicated by "A" as the passing level of this test, and the residual ratio of tensile strength. And one of the residual rates of elongation at break was less than 60%, which was indicated by "C" as the fail level of this test.

6. Oil resistance test (B)
The "oil resistance test" described in JIS C 3005 was performed on each electric wire manufactured by using the coated conductor obtained under the condition of the appearance test (1). In the oil resistance test (B), the oil immersion temperature was 100 ° C., the oil immersion time was 48 hours, and IRM903 was used as the oil.
In the evaluation of this test, the residual ratio of tensile strength and the residual ratio of elongation at break before and after the oil resistance test are both 60% or more, which is indicated by "A" as the passing level of this test, and the residual ratio of tensile strength. And one of the residual ratios of elongation at break was less than 60%, which was represented by "C". This oil resistance test (B) is a reference test.

7. Oil resistance test (C)
The "oil resistance test" described in JIS C 3005 was performed on each electric wire manufactured by using the coated conductor obtained under the condition of the appearance test (1). In the oil resistance test (C), the oil immersion temperature was 100 ° C., the oil immersion time was 72 hours, and IRM903 was used as the oil.
In the evaluation of this test, the residual ratio of tensile strength and the residual ratio of elongation at break before and after the oil resistance test are both 60% or more, which is indicated by "A" as the passing level of this test, and the residual ratio of tensile strength. And one of the residual ratios of elongation at break was less than 60%, which was represented by "C". This oil resistance test (C) is a reference test.

8. Oil resistance test (D)
The "oil resistance test" described in JIS C 3005 was performed on each electric wire manufactured by using the coated conductor obtained under the condition of the appearance test (1). In the oil resistance test (D), the oil immersion temperature was 100 ° C., the oil immersion time was 168 hours, and IRM903 was used as the oil.
In the evaluation of this test, the residual ratio of tensile strength and the residual ratio of elongation at break before and after the oil resistance test are both 60% or more, which is indicated by "A" as the passing level of this test, and the residual ratio of tensile strength. And one of the residual ratios of elongation at break was less than 60%, which was represented by "C". This oil resistance test (D) is a reference test.

9. Abrasion resistance Abrasion resistance test was performed in accordance with EN50305 using each electric wire obtained under the condition of the above appearance test (1). The coating layer was worn using a steel blade having a diameter of 0.45 mm while applying a load of 7 N on the wire sample installed horizontally. The blade was continuously reciprocated until it reached the conductor of the sample. The worn portion was subjected to 90, 180, 270, 360 degrees in the circumferential direction a total of 4 times per sample, and the average value of the number of round trips was calculated. Those with an average value of 50 times or more are "A (advanced)", those with an average value of 30 to 49 times are "B (good)", and those with an average value of 20 to 29 times are "C (allowable range)". , 19 times or less was defined as "D (failure)".

From the results in Table 1, the following was found.
Comparative examples were inferior in appearance, mechanical properties, flame retardancy, oil resistance, and wear resistance. Comparative Example 1 in which the amount of the modified polyolefin resin was too small was inferior in appearance. Comparative Example 2 in which the amount of the modified polyolefin resin was too large and the amount of ethylene-acrylic rubber was too small was inferior in elongation at break and oil resistance. Comparative Example 3 in which the amount of the inorganic filler compounded was too small was inferior in flame retardancy. Comparative Example 4 in which the amount of the inorganic filler compounded was too large was inferior in mechanical properties. Comparative Example 5 in which the amount of the silane coupling agent blended was too small was inferior in tensile strength and oil resistance. Comparative Example 6 in which the amount of the silane coupling agent was too large was inferior in appearance. Comparative Example 7 in which the modified polyolefin resin was not blended was inferior in abrasion resistance. Comparative Example 8 in which ethylene ethyl acrylate was used instead of ethylene-acrylic rubber was inferior in oil resistance. Comparative Example 9 in which ethylene ethyl acrylate was used instead of ethylene-acrylic rubber, the components were mixed at once and kneaded, was inferior in appearance and oil resistance. Comparative Example 10 in which ethylene-propylene-diene rubber was used instead of ethylene-acrylic rubber was inferior in flame retardancy and oil resistance.
On the other hand, Examples 1 to 3 prepared by the production method of the present invention by blending a specific amount of ethylene-acrylic rubber and a modified polyolefin resin and further using a specific amount of an organic peroxide, an inorganic filler, and a silane coupling agent. No. 16 was excellent in appearance, mechanical properties, flame retardancy, oil resistance, and abrasion resistance.
Since it passed the appearance test 1, it was possible to manufacture an electric wire having an excellent appearance by suppressing the occurrence of lumps even under the manufacturing conditions where the linear velocity is low (the screw rotation speed is low).
When the base rubber is 70 to 85% by mass of ethylene-acrylic rubber and 15 to 30% by mass of a polyolefin resin modified with an unsaturated carboxylic acid component, and the blending amount of the inorganic filler is 80 to 200 parts by mass, high tensile strength and oil resistance We were able to obtain a good balance of sex and flame retardancy.

Claims (12)

The following steps (1), steps (2) and steps (3)
Step (1): In the presence of 0.01 to 0.5 parts by mass of the organic peroxide, 40 to 250 parts by mass of the inorganic filler, and radicals generated from the organic peroxide with respect to 100 parts by mass of the base rubber. 1 to 15 parts by mass of a silane coupling agent having a grafting reaction site capable of crosslinking with the base rubber and a silanol condensation catalyst are melt-mixed, and the graft is generated by radicals generated from the organic peroxide. A reaction composition containing a silane crosslinkable rubber is obtained by subjecting the radicalization reaction site and the grafting reaction site of the base rubber having the grafting reaction site and the grafting reaction capable site to a grafting reaction. Step Step (2): A step of molding the reaction composition to obtain a molded body Step (3): A silane crosslinked acrylic rubber having a step of bringing the molded body into contact with water to obtain a silane crosslinked acrylic rubber molded body. It is a method of manufacturing a molded body,
The base rubber contains 55 to 95% by mass of ethylene-acrylic rubber and 5 to 45% by mass of a polyolefin resin modified with an unsaturated carboxylic acid component.
When the step (1) has the following steps (a-1), steps (a-2) and steps (c), but a part of the base rubber is melt-mixed in the following steps (a-2). Has the following steps (a-1), steps (a-2), steps (b) and steps (c).
Step (a-1): At least the inorganic filler and the silane coupling agent are mixed to prepare a mixture. Step (a-2): The mixture and all or a part of the base rubber are mixed with the organic catalyst. In the presence of the oxide, the organic peroxide is melt-mixed at a temperature equal to or higher than the decomposition temperature of the organic peroxide, and the radical generated from the organic peroxide causes the grafting reaction site and the grafting reaction site of the base rubber. Step (b): Step of preparing a catalyst master batch by melt-mixing the rest of the base rubber and the silanol condensation catalyst. Step (b): Step of preparing a catalyst master batch by subjecting the above to a grafting reaction. (C): A step of melt-mixing the silane master batch with the silanol condensation catalyst or the catalyst master batch to obtain the reaction composition. A method for producing a silane crosslinked acrylic rubber molded product. The base rubber contains 70 to 85% by mass of ethylene-acrylic rubber and 15 to 30% by mass of a polyolefin resin modified with an unsaturated carboxylic acid component.
The method for producing a silane crosslinked acrylic rubber molded product according to claim 1, which contains 80 to 200 parts by weight of the inorganic filler. Claim 1 in which the ethylene-acrylic rubber contains a binary copolymer of ethylene and an acrylic acid alkyl ester and a ternary copolymer of ethylene, an acrylic acid alkyl ester and a copolymer component containing a carboxy group. Alternatively, the method for producing a silane-crosslinked acrylic rubber polymer according to 2. The method for producing a silane crosslinked acrylic rubber molded product according to claim 3, wherein the ethylene-acrylic rubber contains 25 to 45% by mass of the binary copolymer and 20 to 60% by mass of the ternary copolymer. The method for producing a silane crosslinked acrylic rubber molded product according to any one of claims 1 to 4, wherein the inorganic filler is a metal hydrate. The method for producing a silane crosslinked acrylic rubber molded product according to any one of claims 1 to 5, wherein the content of the silane coupling agent is 3 to 15 parts by mass with respect to 100 parts by mass of the base rubber. The method for producing a silane crosslinked acrylic rubber molded product according to any one of claims 1 to 6, wherein the silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane. The method for producing a silane crosslinked acrylic rubber molded product according to any one of claims 1 to 7, wherein the silanol condensation catalyst is not substantially mixed in the steps (a-1) and (a-2). A silane crosslinkable acrylic rubber composition produced by the step (1) according to any one of claims 1 to 8. A silane-crosslinked acrylic rubber molded product produced by the method for producing a silane-crosslinked acrylic rubber molded product according to any one of claims 1 to 8. An oil-resistant product containing the silane crosslinked acrylic rubber molded product according to claim 10. The oil-resistant product according to claim 11, wherein the silane crosslinked acrylic rubber molded product is a coating of an electric wire or an optical fiber cable.