JP2014004757A - Production method of rubber molding and production method of electric part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a production method of a rubber molding in which an uncrosslinked resin composition for a semiconductive rubber is laminated on an insulation rubber layer crosslinking-cured beforehand, then the resin composition is crosslinking-cured to obtain a laminate type rubber molding, and interlayer bond strength thereof is improved; and a production method of an electric part using the production method of a rubber molding.SOLUTION: The invention provides: (1) a production method of a rubber molding including a step in which a resin composition for semiconductive rubber is laminated on an insulation rubber layer 1 crosslinking-cured beforehand and is crosslinking-cured to form a semiconductive rubber layer 2, wherein a content of a radical generator based on 100 pts.mass of a resin in the resin composition is 3-6 pts.mass; (2) the aforementioned production method of a rubber molding, wherein the radical generator is a peroxide that has a peroxy group and an organic group in a chemical structure; and (3) the aforementioned production method of a rubber molding, wherein the resin is a copolymer that includes ethylene and propylene.

Description

  The present invention relates to a method for manufacturing a rubber molded product and a method for manufacturing an electrical component.

  A power cable, an electrical component, or the like includes a conductor portion and an insulating portion covering the conductor portion. Depending on the application, this insulating portion is configured by laminating different types of rubber. For example, a configuration is known in which a semiconductive rubber layer is formed so as to be in contact with a conductor portion, and an insulating rubber layer is laminated thereon. In many cases, a two-layer structure in which an insulating rubber layer is laminated on a semiconductive rubber layer as in this example is used. However, as in the power cable of Patent Document 1, a semiconductive rubber layer is further laminated. It may be a layered structure. That is, it has a three-layer structure in which an inner semiconductive rubber layer, an insulating rubber layer, and an outer semiconductive rubber layer are sequentially coated on a conductor that is a core of a power cable. As a method for forming this laminated rubber structure, in Patent Document 1, three types of uncrosslinked rubber resin compositions are laminated and coated on a conductor using an extruder, and then the three layers are collectively crosslinked. A curing method is employed.

JP 2011-222324 A

If the electrical part has a simple shape, the three-layer structure can be cross-linked and cured at once as in the case of the above power cable. However, if the electrical part has a complicated shape, it should be covered and cross-linked and cured. It is difficult. Therefore, in order to reliably form an insulating portion that covers the conductor portion, coating and cross-linking curing may be performed layer by layer. For example, in the case of the three-layer structure, a third semiconductive rubber layer is coated on a second cured insulating rubber layer and crosslinked and cured.
However, in a laminated structure in which an uncrosslinked resin composition for a semiconductive rubber is coated on an insulating rubber layer (second layer) that has already been cross-linked and cured, and the semiconductive rubber layer (third layer) is formed by cross-linking and curing, There was a problem that the interface was easy to peel off. On the other hand, in a laminated structure in which a non-crosslinked resin composition for insulating rubber is coated on a semiconductive rubber layer (first layer) that has already been cross-linked and cured to form an insulating rubber layer (second layer) by cross-linking and curing, The problem is not seen.
The present inventors have examined the cause of the problem. When the crosslinking and curing by vulcanization is performed, the problem does not easily occur, and a crosslinking agent (radical generator) such as an organic peroxide that generates radicals is used. It was found that the above problem becomes remarkable when

  The present invention has been made in view of the above circumstances, and is obtained by laminating an uncrosslinked resin composition for a semiconductive rubber on an insulating rubber layer that has been previously crosslinked and cured, and then crosslinking and curing the resin composition. It is an object of the present invention to provide a method for producing a rubber molded product having improved interlayer bonding strength in a laminated rubber molded product and a method for producing an electrical component utilizing the method for producing a rubber molded product.

According to a first aspect of the present invention, there is provided a method for producing a rubber molded article, comprising: laminating an uncrosslinked resin composition for a semiconductive rubber on an insulating rubber layer that has been previously crosslinked and cured; A method for producing a rubber molded article including a step of forming a layer, wherein the content of the radical generator is 3 to 6 parts by mass with respect to 100 parts by mass of the resin in the resin composition.
According to the production method of the present invention, the radical generator in the resin composition supplies a sufficient amount of radicals during the crosslinking and curing of the resin composition for the semiconductive rubber. Crosslinking between the insulating rubber layer and the semiconductive rubber layer is also performed. As a result, the bonding strength between the layers is sufficiently increased.

The method for producing a rubber molded article according to claim 2 of the present invention is characterized in that, in claim 1, the radical generator is a peroxide having a peroxy group and an organic group in a chemical structure. By using the peroxide, radicals that contribute to cross-linking between layers can be easily supplied in a sufficient amount.
The method for producing a rubber molded article according to claim 3 of the present invention is characterized in that, in claim 1 or 2, the resin is a copolymer containing ethylene and propylene. By using the copolymer, the bonding strength between the layers can be further increased.
The method for producing a rubber molded article according to claim 4 of the present invention is the method according to any one of claims 1 to 3, wherein the resin is a terpolymer composed of ethylene, propylene and a non-conjugated diene monomer. It is characterized by. By using the terpolymer, the bonding strength between the layers can be further increased.
The method for producing a rubber molded article according to claim 5 of the present invention is characterized in that in any one of claims 1 to 4, the insulating rubber layer is a layer containing ethylene-propylene-diene rubber. . By using EPDM as the insulating rubber, the bonding strength between the layers can be further increased.
The method for producing a rubber molded product according to claim 6 of the present invention is characterized in that, in any one of claims 1 to 5, the resin composition contains a carbon material. By including the carbon material in the composition, conductivity can be imparted to the semiconductive rubber layer, and the bonding strength between the layers can be further increased.

In the method for producing an electrical component according to claim 7 of the present invention, an insulating rubber layer is formed by coating an uncrosslinked resin composition for insulating rubber on a base material having a conductor and then curing by crosslinking. Furthermore, a method for producing an electrical component, comprising: forming a semiconductive rubber layer by coating an uncrosslinked resin composition for semiconductive rubber on the insulating rubber layer and crosslinking and curing the composition. The content of the radical generator with respect to 100 parts by mass of the resin in the uncrosslinked resin composition for rubber is 3 to 6 parts by mass.
According to the method for manufacturing an electrical component of the present invention, the insulating rubber layer and the semiconductive rubber layer are individually formed even when the base material has a complicated shape. A part can be formed reliably. Furthermore, the bonding force between the insulating rubber layer and the semiconductive rubber layer can be improved.

According to the method for producing a rubber molded product of the present invention, a laminated rubber obtained by laminating a resin composition for a semiconductive rubber on an insulating rubber layer that has been crosslinked and cured in advance, and then crosslinking and curing the resin composition. In the molded product, the bonding strength between the insulating rubber layer and the semiconductive rubber layer can be improved.
According to the method for manufacturing an electrical component of the present invention, an insulating rubber layer and a semiconductive rubber layer are individually formed in this order on a base material having a conductor, thereby insulating the base material. Can be reliably formed. Furthermore, the bonding strength between the insulating rubber layer and the semiconductive rubber layer can be improved.

It is an example of the rubber molded product produced in the Example.

Hereinafter, although embodiment of this invention is described, this invention is not limited to this embodiment.
<Rubber molded product manufacturing method>
The method for producing a rubber molded article according to the present invention includes a step of forming a semiconductive rubber layer by laminating an uncrosslinked resin composition for a semiconductive rubber on an insulating rubber layer that has been previously crosslinked and cured, and then crosslinking and curing the composition. including.
The rubber molded product may be a rubber product that functions alone, or may constitute a part of another industrial product. In the latter case, the process may be included in the manufacturing process of the industrial product, or may be independent of other processes.

The insulating rubber layer may be formed on the base material or may have a predetermined shape alone. That is, the thickness and shape of the insulating rubber layer are not particularly limited.
The substrate is preferably a conductor through which an electric current flows or a conductor covered with another member. The other members are not particularly limited, and examples thereof include a semiconductive rubber layer. An example of this configuration is the power cable having the three-layer structure described above.
As the conductor, for example, a conductor used for a general electric component can be applied, and specifically, a metal member constituting a core of a power cable (electric wire), a surface wiring of an electronic substrate, and the like can be given.

[Insulating rubber layer]
As the resin constituting the insulating rubber layer that has been crosslinked and cured in advance, a resin that can be crosslinked with the resin constituting the semiconductive rubber layer to be laminated later is preferable. The cross-linking is preferably caused by radicals such as oxygen radicals. Specifically, the resin is preferably a copolymer obtained by polymerizing monomers such as ethylene, propylene, isoprene, acrylonitrile, chloroprene, styrene, and non-conjugated diene monomer, and is a three-component resin composed of ethylene, propylene, and non-conjugated diene. More preferably, it is an original polymer.
The main rubber component of the insulating rubber layer formed by crosslinking the resin is ethylene-propylene rubber (EP), ethylene-propylene-diene rubber (EPDM), nitrile rubber, chloroprene rubber, acrylic rubber, butyl rubber or urethane. Rubber is preferred.
As the resin and the rubber component constituting the insulating rubber layer, one type may be used alone, or two or more types may be used in combination. When two or more kinds are used in combination, the combination or blending ratio of the resin or rubber components is appropriately selected according to the use of the rubber molded product.

  EPDM is obtained by copolymerizing these monomers using ethylene and propylene as main monomers and a small amount of non-conjugated diene monomer having a polymerizable unsaturated bond (double bond). . The blending ratio of each monomer is appropriately adjusted according to the required rubber characteristics.

  As the non-conjugated diene monomer, known ones can be used, and preferred are 5-ethylidene-2-norbornene (ENB), vinyl norbornene (VNB), dicyclopentadiene (DCPD), 1,4-hexadiene (1, 4-HD) and 1,3-butadiene. The said nonconjugated diene monomer may be used individually by 1 type, and may use 2 or more types together. When using 2 or more types together, the combination and ratio may be appropriately selected according to the purpose.

  The insulating rubber layer can be formed by a conventionally known method. For example, it can be formed by preparing an uncrosslinked resin composition for insulating rubber containing the resin and a crosslinking agent, and crosslinking and curing the resin composition on a suitable substrate. It is preferable that content of the said resin in the said resin composition is 35-95 mass%, and it is preferable that it is 40-70 mass%. By setting it as such a range, an insulating rubber layer with better characteristics can be obtained. The remainder in the resin composition can be composed of a solvent for dilution, for example.

  The method for obtaining a cured rubber by crosslinking the resins (polymers) contained in the uncrosslinked resin composition for insulating rubber is not particularly limited, and for example, a vulcanization or radical method can be applied. Examples of the method of generating radicals for crosslinking and curing in the resin composition include a method of containing a radical generator (crosslinking agent) that generates radicals by light irradiation or heating in the resin composition. . The content of the radical generator, light irradiation, and heating conditions are appropriately adjusted according to the type of radical generator used, the type of resin to be cross-linked, and the like. What is necessary is just to set in the range of 5-2.5 mass parts.

The hardness of the insulating rubber layer is not particularly limited, but is preferably 45 to 70, for example, more preferably 50 to 70, and still more preferably 55 to 65. The standard of the hardness is “JIS K 6253-2006”.
When the hardness is within the above range, the bonding strength or adhesion to the semiconductive rubber layer laminated thereon can be enhanced.

  The surface property of the insulating rubber layer is not particularly limited as long as the semiconductive rubber composition can be laminated thereon. The surface may be a smooth surface, or irregularities may be formed on the surface, or the surface may be roughened using a sand blaster or the like. By performing the non-smoothing treatment on the surface of the insulating rubber layer, the adhesion of the semiconductive rubber layer laminated thereon may be improved.

[Method of forming semiconductive rubber layer]
The semiconductive rubber layer is formed by laminating an uncrosslinked resin composition for the semiconductive rubber on the insulating rubber layer previously crosslinked and cured, and crosslinking and curing the laminated resin composition for the semiconductive rubber. Is formed. Thereby, a laminated rubber molded product in which the semiconductive rubber layer is laminated on the insulating rubber layer is formed. The thickness of the semiconductive rubber layer and the shape of the rubber molded product are not particularly limited, and may be appropriately selected depending on the application.

The lamination method is not particularly limited, and a method using a conventionally known extruder, a spin coating method, a screen printing method, or the like can be applied. After the lamination, heat treatment or light irradiation treatment is performed to generate radicals and crosslink and cure.
Moreover, the method of performing lamination | stacking and crosslinking hardening continuously can also be applied. Specifically, the mold process which shape | molds using a type | mold is mentioned. The insulating rubber layer is disposed on a press plate, the uncrosslinked resin composition for the semiconductive rubber is applied on the insulating rubber layer, and another press plate is used using a spacer having an appropriate thickness. Put on. Then, the rubber molding product of the shape along the shape of the said mold is obtained by performing the mold processing which heats and pressurizes.

As the temperature of the said heating, 155-220 degreeC is preferable, 165-200 degreeC is more preferable, 170-185 degreeC is further more preferable.
When it is not less than the lower limit of the above range, not only the crosslinking and curing within the semiconductive rubber layer but also the crosslinking with the insulating rubber layer is sufficiently promoted to sufficiently improve the bonding force between the layers. be able to. When the amount is not more than the upper limit of the above range, the rate of crosslinking and curing is excessively increased, and the crosslinking and curing can be prevented from becoming nonuniform, and the crosslinking and curing can be uniformly performed.

The pressurizing pressure is preferably 2.0 to 10.0 MPa, more preferably 3.0 to 9.0 MPa, and even more preferably 5.0 to 8.0 MPa.
When it is at least the lower limit of the above range, the cross-linking between the insulating rubber layer and the insulating rubber layer can be sufficiently promoted, and the bonding strength between the layers can be sufficiently improved. When the amount is not more than the upper limit of the above range, the elasticity of the formed rubber molded article can be sufficiently secured.

[Resin composition for semiconductive rubber]
The resin constituting the semiconductive rubber layer is preferably one that can be crosslinked with the resin constituting the insulating rubber layer, and more preferably the same resin as that constituting the insulating rubber layer. By using the same resin, the probability that the insulating rubber layer and the semiconductive rubber layer are cross-linked can be increased, and the bonding force between the layers can be further improved.
From the viewpoint of enhancing the thermal stability between the layers, the cross-linking between the layers is preferably formed by radicals.

  As the resin constituting the semiconductive rubber layer, those exemplified as the resin constituting the insulating rubber layer can be applied. Among these, from the viewpoint of increasing the bonding force between the layers, a copolymer containing ethylene and propylene is preferable, and a terpolymer composed of ethylene, propylene and non-conjugated diene is more preferable. Specifically, the main rubber component constituting the semiconductive rubber layer is ethylene-propylene rubber (EP) and ethylene-propylene-diene rubber (EPDM), nitrile rubber, chloroprene rubber, acrylic rubber, butyl rubber or urethane rubber. Preferably, EP or EPDM is more preferable.

  When both the insulating rubber layer and the semiconductive rubber layer contain EP or EPDM, the bonding force between the layers can be further increased. The reason for this is unclear, but it is presumed that the molecular motion of EP or EPDM constituting the surface of each layer is high enough to promote cross-linking between layers.

  The resin and the rubber component constituting the semiconductive rubber layer may be used alone or in combination of two or more. When two or more kinds are used in combination, the combination or blending ratio of the resin or rubber components is appropriately selected according to the use of the rubber molded product.

The semiconductive rubber layer is prepared by preparing a resin composition for a semiconductive rubber containing the resin and a radical generator, laminating the resin composition for the semiconductive rubber on the insulating rubber layer, and crosslinking and curing the resin composition. Can be formed.
However, in the manufacturing method which concerns on this invention, content of the radical generating agent with respect to 100 mass parts of said resins in the resin composition for said semiconductive rubber shall be 3-6 mass parts. This ratio allows the radical generator in the composition to supply a sufficient amount of radicals during crosslinking and curing of the resin composition for the semiconductive rubber, so that not only the crosslinking and curing inside the layer but also the insulating rubber layer Cross-linking between the semiconductive rubber layers is also performed. As a result, the bonding strength between the layers is sufficiently increased. On the other hand, when the content of the radical generator is less than 3 parts by mass, the crosslinking between the layers is not promoted to the extent that the bonding strength between the layers is increased. If it exceeds 6 parts by mass, it becomes difficult to control the timing and speed of crosslinking and curing, and when the crosslinking and curing of the resin composition is not intended, unevenness occurs in the degree of crosslinking in the layer. Therefore, there arises a problem that it becomes difficult to form the predetermined shape.
Except for including the radical generator in the above ratio in the resin composition for the semiconductive rubber, a conventionally known method for forming the semiconductive rubber layer can be applied without departing from the spirit of the present invention. .

  The content of the radical generator with respect to 100 parts by mass of the resin in the resin composition for semiconductive rubber is preferably 3 to 6 parts by mass, more preferably 4 to 6 parts by mass, and still more preferably 5 to 6 parts by mass. . Within the above range, the higher the content of the radical generator, the higher the bonding strength between the layers.

When a diluent solvent or the like is excessively added to the resin composition for semiconductive rubber, the effective concentration of the radical generator that crosslinks and cures the resin may be lowered. In order to prevent this, the concentration of the radical generator in the resin composition is preferably 1.70 to 3.50% by mass, more preferably 2.00 to 3.40% by mass. More preferably, it is 50-3.30 mass%.
Within the above range, the effective concentration of the radical generator can be sufficiently increased, the resin composition can be sufficiently crosslinked and cured, and the bonding strength between the layers can be increased.

  The content of the resin in the resin composition for the semiconductive rubber is preferably 35 to 95% by mass, and preferably 40 to 70% by mass. By setting it as such a range, the bond strength with an insulating layer can be improved further. The remainder in the resin composition can be composed of a solvent for dilution, for example.

  As the radical generator, those that generate radicals by light irradiation or heating are preferable, and those that generate radicals by heating are preferable. By heating, not only radicals are generated, but also the molecular motion of the resin in the resin composition for the semiconductive rubber can be enhanced to further promote cross-linking between layers at the interface with the insulating rubber layer. it can. As the temperature of the said heating, 155-220 degreeC is preferable, 165-200 degreeC is more preferable, 170-185 degreeC is further more preferable.

  The radical generator is more preferably a peroxide having a peroxy group (—O—O—) and an organic group in the chemical structure, that is, an organic peroxide. The organic group is not particularly limited as long as it is a group having a carbon atom.

Examples of the organic peroxide include dicumyl peroxide (DCP), t-butylcumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexine-3, and di-t-butyl. Examples include peroxide, di- (2-t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, and the like. Among these, DCP is preferable because it promotes cross-linking between layers and sufficiently increases the bonding force between the layers.
The said radical generator may be used individually by 1 type, and may use 2 or more types together. Even when two or more kinds are used in combination, the total amount of the radical generating agent relative to 100 parts by mass of the resin in the resin composition for a semiconductive rubber is the content.

The semiconductive rubber layer has a much higher conductivity than the insulating rubber layer. In order to impart the conductivity, the semiconductive rubber layer preferably contains a conductive substance.
As the conductive substance, those contained in a conventionally known semiconductive rubber can be applied. For example, carbon materials such as carbon black, acetylene black, fullerene, carbon nanotube, and graphene are suitable.

The content of the carbon material in the resin composition for the semiconductive rubber is preferably 20 to 100 parts by mass, more preferably 30 to 100 parts by mass with respect to 100 parts by mass of the resin. More preferably, it is 40-80 mass parts.
When the content of the carbon material is less than 20 parts by mass, it is difficult to impart conductivity necessary for the semiconductive layer. When the content of the carbon material exceeds 100 parts by mass, the mechanical properties of the semiconductive rubber layer may be deteriorated or the bonding strength with the insulating rubber layer may not be sufficiently increased.

  The resin composition for the semiconductive rubber contains, as other materials, a filler, a colorant, an oil agent, a lubricant, a stabilizer, an antioxidant, a crosslinking aid, and the like without departing from the scope of the present invention. It does n’t matter.

Sulfur (S) can be used as the crosslinking aid. In this case, the content of sulfur as a crosslinking aid is independent of the content of the radical generator.
The content of sulfur as the crosslinking aid is preferably 0.1 to 0.5 parts by mass, more preferably 0.15 to 0.4 parts by mass, and 0.2 to 0 with respect to 100 parts by mass of the resin. More preferably, 3 parts by mass.

It is preferable that the resin composition for the insulating rubber and the resin composition for the semiconductive rubber are prepared by blending each component and thoroughly mixing them by various means. At this time, each component may be mixed while sequentially adding them, or all components may be mixed at once.
The mixing method of each component is not particularly limited, and for example, a known method of mixing for a predetermined time at normal temperature or under heating conditions using a stirring blade, a ball mill, an ultrasonic disperser, a kneader or the like is applied. That's fine.

The Mooney viscosity (ML1 + 4, 100 ° C.) of the prepared resin composition for insulating rubber and resin composition for semiconductive rubber is preferably 20-100, more preferably 20-80, and even more preferably 30-60.
Here, the Mooney viscosity (ML1 + 4, 100 ° C.) is a value measured by a method based on “JIS K6300-1: (2001)” or “International Standard ASTM D 1646”. By being the said range, each resin composition can be laminated | stacked easily.

<Rubber molded products>
The rubber molded product obtained by the production method of the present invention has a laminated structure in which the semiconductive rubber layer is laminated on the insulating rubber layer.
The rubber molded product may be a rubber product that functions alone, or may constitute a part of another industrial product. As an application of the molded article, it is preferable to use it as a member constituting an insulating part of an electrical component.
The shape of the rubber molded product is not particularly limited, and is suitably selected according to the application, such as a block shape, a plate shape, a sheet shape, a film shape, and a cylindrical shape.

<Method for manufacturing electrical parts>
The method for producing a rubber molded product described above can be applied to the method for producing an electrical component according to the present invention. The method for manufacturing an electrical component of the present invention can be described mainly by dividing it into two steps.

[First step]
The first step is a step of forming an insulating rubber layer by coating an uncrosslinked resin composition for insulating rubber on a base material having a conductor, followed by crosslinking and curing.
As a method of coating the insulating rubber resin composition on the base material, a method of coating so as to satisfy the insulating properties required for the electrical component is preferable. As such a method, a method using a conventionally known extruder, a spin coating method, a screen printing method, a mold processing using a mold, or the like can be applied. The thickness and shape of the insulating rubber layer are not particularly limited, and may be appropriately selected depending on the shape and application of the base material.

The substrate is preferably a conductor through which a current flows or the conductor is covered with another member. The other members are not particularly limited, and examples thereof include a semiconductive rubber layer. An example of this configuration is the power cable having the three-layer structure described above.
The conductor included in the base material is preferably an electric wire or wiring constituting the electric component. Specific examples of the conductor include a metal member constituting a core of a conventionally known power cable (electric wire), a surface wiring of an electronic substrate, and the like.

  Since the description of the resin composition for insulating rubber and the insulating rubber layer is the same as the description of the method for manufacturing a rubber molded product described above, the description thereof is omitted here.

[Second step]
The second step is a step of forming a semiconductive rubber layer by coating an uncrosslinked resin composition for semiconductive rubber on the insulating rubber layer and crosslinking and curing. Under the present circumstances, content of the radical generating agent with respect to 100 mass parts of resin in the resin composition for semiconductive rubber shall be 3-6 mass parts.
The insulating rubber layer formed in the first step is already crosslinked and cured in the second step. Since the description of the method of coating the semiconductive rubber layer on the insulating rubber layer is the same as the description of the method for manufacturing a rubber molded product described above, a description thereof is omitted here.

  According to the method for manufacturing an electrical component of the present invention, the insulating rubber layer and the semiconductive rubber layer are individually formed even when the base material has a complicated shape. A part can be formed reliably. Furthermore, the bonding force between the insulating rubber layer and the semiconductive rubber layer can be improved.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.

[Examples 1-4, Comparative Examples 1-2]
<Preparation of resin composition for insulating rubber and resin composition for semiconductive rubber>
First, each component except a radical generator (crosslinking agent) and sulfur (crosslinking aid) is blended so as to have the composition shown in Table 1, and roll mixing is performed at 120 ° C. for 10 to 15 minutes using two rolls. After smelting, a radical generator and sulfur are further added and kneaded at 50 ° C. for 5 to 10 minutes to prepare an uncrosslinked resin composition for insulating rubber and a resin composition for semiconductive rubber. did.
The Mooney viscosity (ML1 + 4, 100 ° C.) of each resin composition was 38 for the insulating rubber resin composition and 41 to 42 for the semiconductive rubber resin, respectively.

Here, the abbreviations in Table 1 mean the following.
"Phr": means mass part.
“Mitsui EPT3045”: a terpolymer (EPDM) of ethylene, propylene and 5-ethylidene-2-norbornene manufactured by Mitsui Chemicals.
"Dexy clay": R.I. T. T. et al. A filler manufactured by Vanderbilt.
“Carbon Asahi # 35”: Carbon material for coloring manufactured by Asahi Carbon Co., Ltd.
“Acetylene black”: a carbon material for electrical conductivity, manufactured by Denki Kagaku Kogyo.
"Koumo Rex H22": An oil agent for imparting the workability of Nippon Oil Corporation (currently JX Nippon Oil & Energy).
"Paraffin": A lubricant for improving the exfoliation workability of the product of Nippon Oil Corporation (currently JX Nippon Oil & Energy) from the mold.
"Zinc stearate": A lubricant for improving processability manufactured by Sakai Chemical Co., Ltd.
"NOCRACK 300R": An antioxidant for preventing thermal deterioration and oxidation deterioration at the time of manufacture and use by Ouchi Shinsei Chemical Co., Ltd.
"Zinc flower (zinc oxide)": A stabilizer made by Sakai Chemical Co., Ltd. to promote crosslinking.
・ "Io": A crosslinking aid manufactured by Tsurumi Chemical Co., Ltd.
“DCP”: a radical generator manufactured by NOF Corporation (currently Nippon Oil).

<Production of rubber molded product>
The prepared resin composition for insulating rubber was applied on a suitable base material and heat-molded at 170 ° C. for 15 minutes to obtain a sheet-like insulating rubber layer having a length of 100 mm × width 25 mm × thickness 2 mm. On this, the prepared resin composition for semiconductive rubber was laminated | stacked by thickness 2mm. At this time, a mylar sheet was inserted into a 40 mm portion (leading portion) from one end in the vertical direction so that the insulating rubber layer and the semiconductive rubber layer were not in contact with each other. The laminate was sandwiched between press plates using a spacer having a thickness of 3.8 mm, heated at 170 ° C. for 15 minutes, and pressed at a pressure of 7.0 MPa to produce a rubber molded article 10 shown in FIG.

<Evaluation of bonding strength between layers>
Using the rubber molded product 10 that was produced, the lead-out part that prevented the bonding between the layers by inserting the Mylar sheet 3 was picked with a chuck of a tensile tester (Strograph R1) manufactured by Toyo Seiki Seisakusho, and insulated. The rubber layer 1 was pulled upward, the semiconductive rubber layer 2 was pulled downward, and the layers bonded to each other (regions other than the lead portion) were pulled apart. This tensile test was performed in an oven at a temperature of 100 ° C. at a pulling rate of 200 mm / min, and the peeling state was evaluated.

When the peeling state is observed, the case where the interface (surface of each layer) appears as it is is “peeling” (×), and when one rubber is attached to the surface of the other rubber layer (remains), “ Cohesive failure ”(◯), when peeling between layers did not occur, and when the lead portion of any rubber layer picked by the chuck was cut, it was evaluated as“ extension failure ”(」). The results are also shown in Table 1.
“Peeling” (×): Bonding between the insulating rubber layer 1 and the semiconductive rubber layer 2 is poor.
“Cohesive failure” (◯): Bonding between the insulating rubber layer 1 and the semiconductive rubber layer 2 is good.
“Unsatisfied” (◎): Bonding between the insulating rubber layer 1 and the semiconductive rubber layer 2 is better.

  From the above results, it is apparent that Examples 1 to 4 according to the present invention are superior in bonding strength (adhesive strength) between the layers in the rubber molded product as compared with Comparative Examples 1 and 2.

  The present invention can be used for manufacturing electrical components such as power cables.

Claims (7)

A method for producing a rubber molded article comprising a step of forming a semiconductive rubber layer by laminating an uncrosslinked resin composition for a semiconductive rubber on an insulating rubber layer that has been cross-linked and cured in advance and crosslinking and curing,
Content of radical generator with respect to 100 mass parts of resin in the said resin composition is 3-6 mass parts, The manufacturing method of the rubber molded product characterized by the above-mentioned.   The method for producing a rubber molded article according to claim 1, wherein the radical generator is a peroxide having a peroxy group and an organic group in a chemical structure.   The method for producing a rubber molded article according to claim 1 or 2, wherein the resin is a copolymer containing ethylene and propylene.   The method for producing a rubber molded article according to any one of claims 1 to 3, wherein the resin is a terpolymer composed of ethylene, propylene and a non-conjugated diene monomer.   The method for producing a rubber molded product according to any one of claims 1 to 4, wherein the insulating rubber layer is a layer containing ethylene-propylene-diene rubber.   The method for producing a rubber molded article according to any one of claims 1 to 5, wherein a carbon material is contained in the resin composition. An insulating rubber layer is formed by coating an uncrosslinked resin composition for insulating rubber on a base material having a conductor and curing by crosslinking, and further, an uncrosslinked for semiconductive rubber is formed on the insulating rubber layer. A method for producing an electrical component comprising forming a semiconductive rubber layer by coating and curing a resin composition,
The method for producing an electrical component, wherein the content of the radical generator with respect to 100 parts by mass of the resin in the uncrosslinked resin composition for the semiconductive rubber is 3 to 6 parts by mass.

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