JP5048989B2 - Rubber mold materials and rubber mold products - Google Patents

Description

  The present invention relates to a rubber mold material having environmentally friendly characteristics, and a rubber mold product used for an electric wire terminal portion and a connection portion formed using the rubber mold material.

In recent years, eco-material electric wires (hereinafter abbreviated as eco electric wires) have been provided as environmentally friendly electric wires. In order to reduce the burden on the environment with this eco-electric wire, for example, it does not contain halogen elements or toxic heavy metals as insulation coating materials, it emits less smoke during combustion, does not generate corrosion-resistant gas, A resin material having high heat resistance and excellent recyclability is used. Furthermore, if necessary, high flame retardancy and damage resistance may be required as characteristics of the insulating coating material (for example, Patent Document 1).
JP 2002-231068 A

  By using the insulation coating material as described above, eco-friendly eco-electric wires can be obtained. However, when looking at the laying (use) status of the electric wires, there are usually stress cones etc. If parts (parts such as molded products) are used and the entire wire laying system including this is not eco-friendly, it can be said that it is insufficient as an environmental measure.

  Therefore, the present inventor pays attention to the terminal portion and the connecting portion of the electric wire in the electric wire laying system, and the stress cone and the like used here are usually made of a rubber mold material. It was.

  First, as with insulation coating materials, it does not contain halogen elements or toxic heavy metals, it emits less smoke during combustion, does not generate corrosion-resistant gas, has high heat resistance depending on the application, and has excellent recyclability. Therefore, the base rubber material was selected as an ethylene / propylene rubber (in particular, ethylene / propylene / gen copolymer: EPDM alone or a rubber containing this as a main component).

However, when vulcanizing the ethylene / propylene rubber, if a sulfur-containing compound-based vulcanizing agent (crosslinking agent) is used, there is a concern that the acidity may be increased depending on the amount added. The eco electric wire is required to have low acidity (pH = 4.3 or more ) in JIS-C3666-2 (method for measuring gas generated during combustion of electric cable).

Therefore, when the present inventor used a thiuram vulcanizing agent as a sulfur-containing compound vulcanizing agent and changed the amount of addition as appropriate, as shown in FIG. 1 and FIG. It has been found that there is a certain correlation between the amount of sulfur contained in the resin and the acidity of the resulting rubber mold product, that is, the hydrogen ion concentration. More specifically, from the hydrogen ion concentration (5.0 × 10 ⁻⁵ mol / L ) corresponding to the acidity pH = 4.3, vulcanization is performed for eco-friendly rubber mold products. It was determined that the amount of sulfur contained in the agent must be 0.36 wt% to 0.48 wt% (= mass%) or less. FIG. 1 shows a case where the rubber molded product is an insulating rubber (insulator product), and FIG. 2 shows a case where the rubber molded product is a semiconductive rubber (semiconductive product).

Based on this, the present inventor, as will be described later, the sulfur content in the vulcanizing agent (all materials) is 0.36 wt% even when other sulfur-containing compound-based vulcanizing agents are used alone or in combination. It was ascertained that the acidity of the obtained rubber mold product was pH = 4.3 or more when it was ˜0.48 wt% .

  The present invention has been made in view of the above-mentioned viewpoints. A rubber mold material in which ethylene / propylene rubber is selected as a base rubber material and the amount of sulfur in the material is equal to or less than a predetermined value to achieve environmentally friendly characteristics. And a rubber molded product using the same.

The present invention is claimed in claim 1, wherein the base rubber material ethylene propylene rubber, vulcanizing agent thiuram-based, thiazole-based, dithiocarbamate-based, sulfur alone or in the rubber molding material is these combination, the The rubber mold material is characterized in that the total amount of sulfur in the rubber mold material is 0.36 wt% to 0.48 wt% .

  2. The rubber mold according to claim 1, wherein the ethylene-propylene rubber is an ethylene-propylene-gen copolymer (EPDM) alone or a rubber mainly composed thereof. In the material.

3. The present invention described is in the base rubber material, a filler, a carbon, a softener, a lubricant, an anti-aging agent, wherein the optionally added one or more ones selected from stabilizers according It exists in the rubber mold material of claim | item 1 or 2 .

According to a fourth aspect of the present invention, there is provided a rubber mold product which is molded from the rubber mold material according to any one of the first to third aspects.

In the rubber mold material of the present invention and the rubber mold product obtained thereby, the base rubber material is ethylene / propylene rubber, and the total sulfur content in the material is 0.36 wt% to 0.48 wt%. The degree can be set to pH = 4.3 or more.
That is, the same characteristic as an eco electric wire can be acquired about acidity. Other characteristics such as not containing halogen elements or toxic heavy metals, low smoke generation during combustion, no generation of corrosion-resistant gas, high heat resistance, excellent recyclability, etc. Obtained by the characteristics of the base rubber material.

  As a result, since the eco-friendly rubber molded product used for the electric wire terminal portion and the connecting portion such as the stress cone can be made ecological, the electric wire laying system as a whole can be made eco-friendly as a result.

  The base rubber material used in the present invention is ethylene / propylene / gen copolymer (EPDM) alone or ethylene / propylene rubber containing this as a main component. When EPDM is the main component, for example, an ethylene / propylene copolymer or natural rubber is blended and used as the other component as long as various properties are not impaired. EPDM includes a copolymer of ethylene, propylene, and a gen-based monomer such as ethylidene norbornene, 1,4 hexagen, dicyclopentagen or the like. Moreover, the thing whose propylene content in EPDM is about 30-55 wt% is desirable. It is because moderate hardness and elongation required as a rubber mold product are ensured by setting it as this content.

  Of course, this base rubber material does not contain halogen elements or toxic heavy metals, and the main chain is made of a chemically stable saturated hydrocarbon, so that various excellent characteristics such as heat resistance, cold resistance, Excellent chemical properties, weather resistance, ozone resistance, electrical properties (corona resistance, tracking resistance, etc.) and processability can be obtained. In the present invention, for example, Mitsui EPT4021 (trade name, manufactured by Mitsui Chemicals) was used as the commercially available product.

Some examples of specific compounds of the sulfur-containing vulcanizing agent are shown in FIG. 3 (table). This table shows the amount of sulfur contained in the compound (sulfur ratio =%). Incidentally, TT of thiuram type used in Example and Comparative Example to be described later (tetramethylthiuram disulfide), TET (tetraethyl thiuram disulfide), TBT (tetrabutyl thiuram disulfide), TRA (dipentamethylenethiuram tetrasulfide) or thiazole Commercial products of MDB (2- (4′-morpholinodithio) benzothiazole), DM (di-2-benzothiazolyl disulfide), and M (2-mercaptobenzothiazole) are all manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. belongs to. A commercial product of dithiocarbamate TL (tellurium diethylthiocarbonate) is manufactured by Kawaguchi Chemical Co., Ltd. A commercial product of sulfur alone is manufactured by Karuizawa Refinery.

  Some examples of specific compounds of the sulfur-containing vulcanizing agent are shown in FIG. 3 (table). This table shows the amount of sulfur contained in the compound (sulfur ratio =%). In addition, Tyrium-based TT (tetramethyltyramium disulfide), TET (tetraethyltyramium disulfide), TBT (tetrabutyltyramium disulfide), TRA (dipentamethylenetyramium tetrasulfide) used in Examples and Comparative Examples described later ) And thiazole-based MDB (2- (4′-morpholinodithio) benzothiazole), DM (di-2-benzothiazolyl disulfide), and M (2-mercaptobenzothiazole) are all in Ouchi It is made by Shinsei Chemical Industry. A commercial product of dithiocarbamate TL (tellurium diethylthiocarbonate) is manufactured by Kawaguchi Chemical Co., Ltd. A commercial product of sulfur alone is manufactured by Karuizawa Refinery.

  And this addition amount is preferably 1 to 3 parts (parts by mass) in order to obtain an appropriate degree of vulcanization with respect to 100 parts (parts by mass) of the base rubber material. 100 parts of material (parts by weight)).

  In addition to the vulcanizing agent, the following can be appropriately added to the base rubber material in accordance with the required specifications as in the case of a normal rubber material. Fillers, carbon, softeners, lubricants, anti-aging agents, stabilizers and the like. In addition, a flame retardant etc. can be added if necessary.

  Examples of the filler include calcium carbonate, aluminum hydroxide, those obtained by surface treatment with a silane coupling agent, talc, fine powder talc, clay, silica, and the like. With these additions, it is possible to adjust mechanical properties such as tensile strength, tear strength, and abrasion resistance of rubber, and electrical properties such as tracking resistance. This addition amount is preferably 50 to 150 parts. Burgess KE (manufactured by Shiraishi Calcium Co., Ltd.) was used in Examples and Comparative Examples described later. The addition of carbon can improve the reinforcing effect and weather resistance. This addition amount is preferably 1 to 2 parts for insulating rubber and 40 to 80 parts for semiconductive rubber. In Examples and Comparative Examples described later, carbon Asahi # 35 (manufactured by Asahi Carbon Co.) was used for the insulating rubber, and acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd.) was used for the semiconductive rubber.

  The softening agent is for ensuring the flexibility of rubber and includes various oil-based ones (mineral oils, synthetic oils, etc.). Specific examples include process oil. This added amount needs to be within a range of 8.00 wt% or less in the material, but is preferably 5 to 15 parts. By setting the amount within this range, an increase in acidity can be avoided. In Examples and Comparative Examples described later, Thumper 2280 (manufactured by Nippon San Oil Co., Ltd.) was used as process oil.

  Examples of the lubricant include paraffin / wax, liquid paraffin, paraffin-based synthetic wax, polyethylene wax, zinc stearate, hydroxystearic acid, fatty acid amide, and fatty acid ester. This addition amount is preferably 3 to 6 parts. In Examples and Comparative Examples described later, paraffin (manufactured by Nippon Oil Corporation) and zinc stearate (manufactured by Sakai Chemical Industry Co., Ltd.) were used.

  Antiaging agents include naphthylamine, diphenylamine, p-phenyldiamine, quinoline, hydroquinone derivatives, monophenols, thiobisphenols, hindered phenols, phosphites, and the like. This addition amount is preferably 0.5 to 1.5 parts. In Examples and Comparative Examples described later, Irganox 1010 (manufactured by Ciba Specialty Chemicals) was used. Examples of stabilizers include zinc white, activated zinc white, surface-treated zinc white, composite zinc white, zinc carbonate white, magnesium oxide, surface-treated magnesium oxide, calcium hydroxide, stearic acid, oleic acid, and amines. . This addition amount is preferably 3 to 5 parts. In the examples and comparative examples described later, zinc white (manufactured by Mitsui Kinzoku Mining Co., Ltd.) was used.

In Tables 1 to 4, samples of rubber molds (rubber stress cones, Examples 1 to 12 , Reference Examples 1 to 2 and Comparative Examples 1 to 6) were manufactured and obtained using the materials described above. Acidity (pH), hydrogen ion concentration (mol / L), and sulfur content (wt%) were determined.
In addition, the addition amount of the material in each table | surface is shown by the number of parts (mass part) as mentioned above. The blending ratio is indicated by wt% (= mass%). In addition, the three digits after the decimal point are rounded off when calculating the ratio. In addition, in the above rubber molded products, those of Examples 1 to 9 , Reference Example 1 and Comparative Examples 1 to 4 having a small amount of carbon addition are insulating rubber rubber stress cones. Examples 10 to 12 and Reference Example 2 Comparative Examples 5 to 6 are semiconductive rubber rubber stress cones.

From these Tables 1 to 4, when the total sulfur amount in the vulcanizing agent in the ethylene / propylene rubber of the base rubber material is 0.36 wt% to 0.48 wt% (Examples 1 to 12 ), the acidity is too high. It can be seen that a pH = 4.3 or higher is obtained. Of course, when sulfur is not contained (reference examples 1-2), it turns out that acidity is low. On the other hand, when the total amount of sulfur in the vulcanizing agent exceeds 0.48 wt% (Comparative Examples 1 to 6), the acidity is less than pH = 4.3, and only high acidity (strong) is obtained. I can't understand.

In the above description, the total sulfur amount in the material is the same as the total sulfur amount in the vulcanizing agent. However, the present invention is not limited to this and is mixed into the material for some reason. Including the amount of sulfur. For example, since sulfur is mixed in by other additives that are added in various ways , it is necessary in the present invention that the total sulfur amount in the material including this sulfur amount is 0.36 wt% to 0.48 wt%. It is said.

It is the graph which showed the relationship between the amount of sulfur in a vulcanizing agent in a rubber material (insulating material), and hydrogen ion concentration. It is the other graph which showed the relationship between the amount of sulfur in a vulcanizing agent, and hydrogen ion concentration in rubber material (semiconductive material). It is the table | surface which showed the kind of vulcanizing agent.

Claims (4)

In a rubber mold material in which the base rubber material is ethylene / propylene rubber and the vulcanizing agent is thiuram, thiazole, dithiocarbamate, sulfur alone or a combination thereof, the total amount of sulfur in the rubber mold material is A rubber molding material characterized by being 0.36 wt% to 0.48 wt% .   2. The rubber mold material according to claim 1, wherein the ethylene / propylene rubber is ethylene / propylene / gen copolymer (EPDM) alone or a rubber mainly composed thereof. The rubber mold material according to claim 1 or 2, wherein one or more selected from fillers, carbon, softeners, lubricants, anti-aging agents, and stabilizers are appropriately added to the base rubber material. . A rubber mold product, which is molded from the rubber mold material according to any one of claims 1 to 3 .

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