JPH033569B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for efficiently manufacturing vulcanized rubber products by compositing unvulcanized rubber moldings. In rubber factories, unvulcanized rubber moldings are combined with similar moldings such as unvulcanized rubber moldings and vulcanized moldings of the same or different compositions, or dissimilar moldings such as plastic moldings and metal plates. The unvulcanized rubber molded product is then vulcanized to produce a vulcanized rubber product or semi-finished product. Molded unvulcanized rubber moldings are often stacked on top of each other for temporary storage until they are composited and vulcanized. Due to its tackiness, the rubber parts of unvulcanized rubber moldings may stick together, or it may be necessary to separate the parts that are in close contact with each other to form a composite, and in severe cases, it may be necessary to re-mold. This created problems in efficiently manufacturing rubber products. In addition, if unvulcanized rubber moldings are left on a workbench or storage table,
The unvulcanized rubber adheres to these tables, and it is necessary to peel off the adhered portion, which may significantly reduce the workability of manufacturing rubber products. Furthermore, in order to assemble accurately in compounding, it may be necessary to modify the product, and it is necessary to prevent the unvulcanized rubber molded product from coming into close contact with molded products of the same or different type. As a method for efficiently manufacturing rubber products by preventing the unvulcanized rubber from adhering to moldings of the same or different type in such unvulcanized rubber moldings, molding of the same or different type as the unvulcanized rubber molding is Methods of inserting a polyethylene film between objects or placing an unvulcanized rubber molded object on a polyethylene film are used, but this method requires time and effort to remove the polyethylene film. In addition, if small pieces of polyethylene film that cannot be completely removed are mixed in, there is a problem in that the performance of the rubber product obtained by vulcanization deteriorates. In order to solve the problems of the prior art as described above, the inventors of the present invention have made various studies and found that a molded article made of unvulcanized rubber and a molded article of the same or different type as the unvulcanized rubber are combined and then vulcanized. In producing a vulcanized rubber product, a film of a vulcanizable crystalline polymer having a melting point of 40 to 100°C is interposed between the molded product () and the composite material (). By vulcanizing the molded product () made of unvulcanized rubber, it is possible to prevent the rubber of the molded product () from coming into close contact with the rubber, plastic, metal, etc. of the molded product (), and also to compound it. Even if the film is composited and vulcanized without removing the film, the crystalline polymer forming the film diffuses into the unvulcanized rubber at the vulcanization temperature. Moreover, since the process is co-vulcanized with unvulcanized rubber, the resulting vulcanized rubber products show almost no deterioration, and the inventors have discovered that vulcanized rubber products can be manufactured efficiently, leading to the completion of the present invention. In the present invention, molded products made of unvulcanized rubber () include natural rubber (NR), cis-1,4-polyisoprene rubber (IR), polybutadiene rubber (BR), and styrene-butadiene copolymer rubber (SBR). ), styrene-isoprene copolymer rubber (SIR), acrylonitrile-butadiene copolymer rubber (NBR), acrylonitrile-isoprene copolymer rubber (NIR), chloroprene rubber (CR), ethylene-propylene copolymer rubber (EPR or
Vulcanization of vulcanizing agents such as sulfur, vulcanization accelerators, activators, metal oxides, metal carbonates, fatty acids or their derivatives, etc. to rubber such as EPDM) or butyl rubber (IIR), or mixtures thereof. Contains accelerators, fillers, rubber reinforcing agents, rubber softeners, plasticizers, anti-aging agents, antioxidants, anti-ozonants, ultraviolet absorbers, dyes, pigments or tackifying resins as required. It means an unvulcanized rubber composition formed by molding the composition into a sheet, plate, rod, or hose shape. In the present invention, remarkable effects are observed in adhesive unvulcanized rubber molded products containing sulfur. The molded product may be reinforced with chemical fibers, glass fibers, woven fabrics or attached woven fabrics thereof, metal cords, or metal plates. In addition, molded products of the same type as the unvulcanized rubber molded product () include the aforementioned unvulcanized rubber molded product (′) itself;
It means an unvulcanized rubber molded product ('') or a vulcanized molded product () having a different composition from the molded product, and a different type of molded product means a molded product made of plastics or a metal plate, etc. Furthermore, rubber products include unvulcanized rubber molded products (), unvulcanized rubber molded products ('), unvulcanized rubber molded products (''), or vulcanized molded products ().
or different types of moldings such as moldings made of plastics or moldings of metal materials (e.g. iron, steel or copper),
Refers to products or semi-finished products obtained by vulcanization, such as tires, belts, hoses, footwear, rubber cloth, etc.
Examples include various rubber products such as rubber rolls and anti-vibration rubber, and semi-finished products thereof. A major feature of the present invention is the use of a vulcanizable crystalline polymer film having a melting point of 40 to 100°C, which has various effects, which will be explained below. In the present invention, if the vulcanizable crystalline polymer used in the form of a film has a high melting point, the vulcanizing agent (sulfur) blended to make the unvulcanized rubber molding () during vulcanization, Rubber compounding chemicals such as accelerators or vulcanization accelerators do not diffuse sufficiently into the vulcanizable crystalline polymer used in film form, reducing the performance of the rubber product obtained by vulcanization. It is necessary that the melting point of the vulcanizable crystalline polymer used in film form does not exceed 100°C. On the other hand, if the melting point is low, the film strength at room temperature will be insufficient, so the melting point needs to be 40°C or higher. In the present invention, the melting point refers to the temperature of the endothermic peak on the highest temperature side of the endothermic peak due to melting of the crystal obtained by differential thermal analysis. In addition, the crystalline polymer having a melting point of 40 to 100°C used in the form of a film in the present invention is not co-cured with the unvulcanized rubber in the unvulcanized rubber molded product (), but is vulcanized without removing the film. Since curing deteriorates the physical properties of the vulcanized rubber product, especially the strength at the interface of the molded product, it is necessary to be able to vulcanize it and to co-vulcanize it with unvulcanized rubber. Polymers satisfying these conditions may be crystalline polymers made of conjugated dienes such as butadiene, isoprene, or chloroprene, and the most preferred examples are trans-1,4-polyisoprene or syndiotactic polymers. 1,2-polybutadiene is mentioned. In particular, trans-1,4-polyisoprene is most suitable. If the crystallinity of these crystalline polymers is low, the strength of the film obtained from the polymer will be insufficient.
The polymer needs to have a structure exhibiting high stereoregularity; for example, in the case of trans-1,4-polyisoprene, it contains 90% or more, preferably 95% or more of trans-1,4-bonds. In the case of syndiotactic-1,2-polybutadiene, it is desirable to have 1,2-bonds of 90% or more, preferably 95% or more. Examples of such crystalline polymers include natural products of trans-1,4-polyisoprene such as balata and gutta percha, or those polymerized by conventional methods. In the case of trans-1,4-polyisoprene, which is preferably used in the present invention, isoprene monomers are polymerized using a Ziegler catalyst or syndiotactic.
In the case of 1,2-polybutadiene, it can be obtained by polymerizing butadiene monomers using an anionic catalyst. Such a crystalline polymer is made into a film by a conventional method using an extruder. At that time, natural rubber, synthetic cis-1,4
- Synthetic rubbers such as polyisolene rubber (IR), polybutadiene rubber (BR), styrene-diene copolymer rubber (SBR or SIR), acrylonitrile-diene copolymer rubber (NBR or NIR) may be blended. Also an anti-aging agent, usually used in rubber factories,
Antioxidants, antiozonants, ultraviolet absorbers,
Dyes, pigments, rubber reinforcing agents, fillers, rubber softeners,
Rubber compounding chemicals such as plasticizers or tackifying resins may also be blended. Note that a rubber adhesive may be applied to one side of the obtained film. If the film of the crystalline polymer obtained in this way is too thin, it may not be applied to or inserted between unvulcanized rubber moldings () or other moldings (). 5 to 200 microns, because the strength will be insufficient and if it is too thick, the physical properties of the resulting vulcanized rubber product will deteriorate.
It is especially desirable to have a thickness of 20 to 100 microns. The film thus obtained is placed between an unvulcanized rubber molded product obtained by a conventional method and a molded product of the same or different type as the unvulcanized rubber molded product. As for the method. There are various methods such as pasting the film on the molded product () and arranging the molded product (), placing the film on the molded product () and replacing the molded product (), etc. Variations are possible. Note that if a film is attached to the molded product (), it will be extremely easy to compose it, and when the molded products are stacked for storage, not only will the rubber not adhere to each other, but for example, composite When the conversion is performed on a drum, it also has the advantage that it is easy to attach and detach from the drum. In this way, a composite product consisting of an unvulcanized rubber molded article interposed with a film of a vulcanizable polymer having a melting point of 40 to 100°C and a molded article of the same or different type as the unvulcanized rubber molded article is obtained. However, since the unvulcanized rubber molded product () is not in close contact with the molded product () or the molded product (), it is extremely easy to
In addition, it can be easily placed at the location where it is to be combined. Therefore, the compositing work can be performed extremely efficiently. There are many advantages especially when combining two or more molded products. The composite thus obtained is vulcanized by a conventional method at 100°C or higher, preferably 120°C or higher, where sulfur is easily vulcanized, to form a rubber product. A film of vulcanizable polymer with a melting point of 40-100° C. dissolves during vulcanization, diffuses into the unvulcanized rubber molding () and covulcanizes with the unvulcanized rubber. Therefore, the interface of the molded product will not be easily peeled off. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples in any way. Comparative Example 1 An unvulcanized rubber composition of synthetic cis-1,4-polyisoprene rubber was kneaded using an 8-inch open roll according to the formulation shown in Table 1, and the mixture was kneaded to a thickness of 3 mm.
An unvulcanized rubber sheet was separated. Cut out two specimens of 15cm x 15cm from this unvulcanized rubber sheet, stack them tightly, and cut them horizontally 5cm along one side.
A Teflon sheet measuring 15 cm x 15 cm was inserted to create a composite of unvulcanized rubber sheets. This composite was then press-vulcanized at 135°C for 60 minutes to obtain a vulcanized rubber sheet. When the Teflon sheet was removed from the vulcanized rubber sheet and visually inspected, there was a part where the two unvulcanized rubber sheets were vulcanized together (part A), and a part where the two unvulcanized rubber sheets were vulcanized together, and a part where they were not integrated due to the presence of the Teflon sheet and were vulcanized separately. It was found that a vulcanized rubber sheet having both a part (B part or B' part) was obtained. In addition, when the above-mentioned composite sheet of unvulcanized rubber sheets is stacked without being pressed, the unvulcanized rubber sticks together and is extremely difficult to separate. Cut out a 1 cm wide specimen from the vulcanized rubber sheet in a direction perpendicular to the vertical direction of the inserted Teflon sheet, that is, parallel to the horizontal direction of the inserted Teflon sheet, and use parts B and B' as chucks. A 90 degree peel test was performed using scissors and a tensile speed of 50 cm/min. In the peel test, no peeling was observed at part A, and breakage occurred at the chuck scissors part (part B or B'), but the stress at that time was 87 kg/cm ² .

【table】

[Table] Example 1 A dispensing sheet (2 mm x 15 cm x 15 cm) prepared in the same manner as Comparative Example 1 was placed along one side by 5 cm horizontally.
Place a 15cm tall Teflon sheet, and place trans-1,4-polyisoprene with a melting point of 67℃ (cis-1,4 bond content: 99%) on the part not covered with the Teflon sheet. Thickness obtained by extruding TP-301)
The 50 micron sheets (10 cm x 15 cm) were placed tightly on top of each other, and then the dispensed sheet was placed on top of the dispensed sheet and pressed to form a composite. After pressing, when the two divided sheets were pulled from both sides, they were easily peeled off. In addition, when examined two weeks later, the above-mentioned releasability remained unchanged. The complex was then prepared in the same manner as in Example 1.
Press vulcanization was performed at 135°C for 60 minutes. Visual inspection of the cross section of the obtained vulcanized rubber sheet revealed that trans-
Its presence was not confirmed in the portion where 1,4-polyisoprene was interposed, and the upper and lower two sheets were completely integrated. A 90 degree peel test was conducted on this vulcanized rubber sheet in the same manner as in Comparative Example 1. In this case, as in Comparative Example 1, cutting was performed at the gripping portion, and the stress at that time was 86 Kg/cm ² . This is comparative example 1
This is almost the same value as when a vulcanized rubber sheet was manufactured without intervening a trans-1,4-polyisoprene film, and in this example also, when laminating the vulcanized rubber sheet with a trans-1,4-polyisoprene film interposed, This is presumed to indicate that the two unvulcanized rubber sheets were completely integrated during vulcanization. Comparative Example 2 Two unvulcanized rubber sheets with a thickness of 2 mm produced in the same manner as in Comparative Example 1 were stacked and press-vulcanized at 135° C. for 60 minutes to obtain a vulcanized rubber sheet. JIS No. 3 dumbbells were punched out from the vulcanized rubber sheet, and a tensile test was conducted at a tensile speed of 50 cm/min. The results are shown in Table 2. Example 2 A transformer with a melting point of 67°C was placed between two unvulcanized rubber sheets with a thickness of 2 mm produced in the same manner as in Comparative Example 1.
1,4-Polyisoprene (Kuraprene TP-301)
films (thickness, 50 microns) were stacked on top of each other and pressed to form a composite. When the unvulcanized rubber sheets on both sides were pulled, they were easily peeled off. The composite was then press-vulcanized at 135°C for 60 minutes to obtain a vulcanized rubber sheet. When this sheet was subjected to a tensile test in the same manner as in Comparative Example 2, the results shown in Table 2 were obtained. A comparison with Comparative Example 2 shows that the tensile properties of the vulcanized rubber sheet are not affected in any way by the presence of the trans-1,4-polyisoprene film.

[Table] Example 3 Instead of a 50 micron thick sheet obtained by extrusion of trans-1,4-polyisoprene, syndiotactic-1 having a melting point of 75°C
2-polybutadiene (1,2 bond amount, 90% or more;
In addition to using a 30 micron thick sheet obtained by extruding JSR RB820 manufactured by Japan Synthetic Rubber Co., Ltd.,
Two unvulcanized rubber sheets were prepared in the same manner as in Example 1,
In the meantime, a composite product in which syndiotactic-1,2-polybutadiene was inserted was prepared. In addition, when this was pressed and the releasability of the unvulcanized rubber sheet was examined, the releasability was extremely good. Next, the above composite was heated at 135℃ for 60 minutes.
Press vulcanization was performed for a minute to obtain a vulcanized rubber sheet. When a 90 degree peel test was carried out using this vulcanized rubber sheet in the same manner as Comparative Example 1, breakage occurred at the gripping part, and the stress was 84 Kg/cm ² , which is almost the same as the result of Comparative Example 1. It was hot.
Therefore, it can be seen that even if syndiotactic-1,2-polybutadiene is interposed between unvulcanized rubber sheets, the physical properties of the vulcanized product are not affected at all.

Claims (1)

[Claims] 1. In manufacturing a vulcanized rubber product by vulcanizing a molded product made of unvulcanized rubber and a molded product of the same or different type as the molded product, A rubber characterized in that a film of a vulcanizable crystalline polymer having a melting point of ~100°C is interposed between the molded product () and the molded product () to form a composite, and then vulcanized. How the product is manufactured. 2. The manufacturing method according to claim 1, wherein the vulcanizable crystalline polymer having a melting point of 40 to 100°C is trans-1,4-polyisoprene. 3. The manufacturing method according to claim 1, wherein the vulcanizable crystalline polymer having a melting point of 40 to 100°C is syndiotactic-1,2-polybutadiene. 4. The manufacturing method according to claim 1, wherein the film has a thickness of 5 to 200 microns.