JPH11198148A - Mold for manufacturing vulcanized rubber product and manufacture of vulcanized rubber product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a frequency of cleaning a mold by forming a vulcanized rubber product without treating such as plating and/or fluroresin coating or the like of its surface after finishing with a high alloy steel, thereby reducing occurrence of a mold dirt. SOLUTION: A high allay steel is adopted as a material. And, a vulcanized rubber product is formed without entirely surface treating such as plating and/or fluororesin coating or the like on a finished surface. In the case of manufacturing the product even without such surface treating, a mold contamination is suppressed, and reduced. As a result, a frequency of cleaning the mold is remarkably reduced, and a productivity is remarkably increased. The steel is obtained by adding 10 to 15 wt.% of chromium as an alloy element to a carbon steel, as a modified product of a SUS420F. and, a compression molding machine (press molding machine), a transfer molding machine, an injection molding machine or the like is used according to the type of the rubber product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for producing a vulcanized rubber product, and more particularly, to reduce mold contamination without applying a treatment such as plating to a finished surface of the mold. The present invention relates to a rubber product-manufacturing mold and a method for producing a vulcanized rubber product, which are excellent in productivity because the frequency of cleaning is extremely low and are capable of producing a highly accurate vulcanized rubber product.

[0002]

2. Description of the Related Art In many cases, various rubber products are usually produced by compression molding, transfer molding, injection molding or the like using a mold. As the mold, usually SUS4
A mold is used in which a material such as 20 series is cut, and the surface is finished, plated with chromium, nickel, or the like, and optionally subjected to a surface treatment such as a fluorine resin processing.

[0003] In chromium plating, which is said to be the most durable, the plating film of the mold has a turtle-like shape, so that volatiles from the rubber composition penetrate into the gaps between the turtles and the coating film is formed. In this case, so-called mold stains occur, which impair the durability of the rubber product and form deposits on the surface of the coating, thereby impairing the surface smoothness of the rubber product and lowering the product accuracy. In order to remove the stains on the mold, the mold must be cleaned, and a large amount of time is required for cleaning the mold, which is a major cause of lowering the productivity.

[0004] In the electroplating, electric charges are easily collected on the sharply protruding portion of the mold surface, and the amount of electrodeposition increases. The roughness is increased and the roughness further increases. Even if polishing is performed after plating, particularly sharp corners can hardly be polished. Even if polishing is performed after plating, it is difficult to prevent mold contamination, and there is a problem that the frequency of mold cleaning is not reduced.

On the other hand, by coating the finished surface of the mold or its plating surface with a fluororesin, the corrosion resistance is improved, and although there is a certain decrease in the amount of deposits on the mold, the frequency of the mold cleaning is greatly increased. No decrease is expected. or,
It is difficult to form a fluororesin film with a uniform thickness, and it is not suitable for manufacturing rubber products that require precision. There is also a problem that the precision of the product is reduced due to the abrasion of the resin film.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to significantly reduce the occurrence of mold contamination and greatly reduce the frequency of mold cleaning, thereby significantly improving productivity and improving surface smoothness. And a method for producing a vulcanized rubber product using the mold. As a result of various studies on the material of the mold, the present inventor found that when the mold was formed using high alloy steel, the surface of the mold after finishing was not subjected to a surface treatment such as plating or a fluorine resin coating. The present inventors have found that the occurrence of mold contamination is significantly reduced, and as a result, the frequency of mold cleaning can be significantly reduced, thus completing the present invention.

[0007]

The above objects of the present invention are attained by the following inventions. That is, the present invention provides a rubber product manufacturing mold and the above-mentioned mold, which are made of high alloy steel, and whose surface after finishing is not subjected to a treatment such as plating and / or fluororesin coating. A method for producing a rubber product, characterized in that it is used.

[0008]

Next, the present invention will be described in more detail with reference to preferred embodiments of the present invention. The rubber product targeted by the present invention is not particularly limited as long as it is a rubber product manufactured using a mold such as compression molding or injection molding, but among others, for medical use, rubber stoppers for food and cosmetic containers, and Rubber products for medical devices are preferred. For example,
Rubber stoppers of various sizes and shapes for vial preparations, pistons (slip stoppers) for syringes, rubber stoppers for sealing containers and syringes (caps for attaching needle injection unit, for inserting in syringe barrel, and sealing lower end), etc. No.

The mold used in the production of the vulcanized rubber product in the present invention uses a high alloy steel as a material and is formed into a predetermined shape by cutting or the like in accordance with the usual method of mold production. It is obtained by subjecting a surface to a surface finishing according to a conventional method. The features of the mold of the present invention are that the material is a high alloy steel and that no surface treatment such as plating and / or fluororesin coating is performed on the surface finishing surface performed in the conventional mold. . Despite not performing such surface treatment, mold contamination is suppressed and reduced in the production of vulcanized rubber products, and as a result, the frequency of cleaning the mold is significantly reduced, and productivity is significantly increased. A remarkable effect is achieved.

[0010] The high alloy steel used in the manufacture of the mold in the present invention is prepared by adding 10 to 15% by weight of chromium as an alloying element to carbon steel.
It is an improved product of SUS420F. Such a high alloy steel is, for example, trade name RAMAX S
(Manufactured by Wooddeholm Co., Ltd.) and can be easily obtained.

The raw rubber used for producing the vulcanized rubber product using the mold of the present invention may be selected from those satisfying the characteristics required for the rubber product. Not restricted. For example, in the manufacture of rubber stoppers for pharmaceuticals and medical devices, butyl rubber, chlorinated butyl rubber, brominated butyl rubber, divinylbenzene copolymer partially crosslinked butyl rubber, high cis polybutadiene rubber, high cis polyisoprene rubber, epichlorohydrin rubber, styrene- Butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), ethylene-propylene-diene monomer terpolymer rubber (EPDM), acrylic rubber and the like are used.

In order to manufacture a vulcanized rubber product, a raw material rubber is prepared by adding a sulfur vulcanizing agent such as a sulfur vulcanizing agent / vulcanizing aid / vulcanizing accelerator or an organic oxide vulcanizing agent / crosslinking auxiliary. Organic peroxide vulcanization system, if necessary, reinforcing agents such as silica, fillers such as calcium carbonate, coloring agents such as carbon black, processing aids, antioxidants and other compounding agents are added, and a Banbury mixer is added. ,
A vulcanizable rubber composition produced using a usual mixer such as a roll or an internal mixer is used. Each of the above compounding agents can be used those conventionally used in the manufacture of various rubber products, and the type and amount of the compounding agent are determined so as to satisfy the performance required for the vulcanized rubber product. Well, there is no particular limitation. When the rubber product is a rubber product for pharmaceuticals or medical devices, it is important to determine the type and amount of the compounding agent so as to conform to various official standards due to safety and hygiene requirements.

A vulcanized rubber product is produced by a molding machine using the above vulcanizable rubber composition and mounting a mold of the present invention in which a male or female mold is formed in a rubber product shape. Depending on the type of rubber product, a compression molding machine (press molding machine), a transfer molding machine, an injection molding machine, or the like is used.
In the case of using a compression molding machine, at least the surface of the vulcanizable rubber composition and a fluorine-based resin film or polyethylene, an α-olefin-based polymer film such as polypropylene by laminating and molding. A vulcanized rubber product partially coated with the film can be produced.

[0014]

Next, the present invention will be described specifically with reference to examples. Example 1 and Comparative Example 1 A rubber stopper for a vial formulation formed using a high alloy steel (RAMAX S manufactured by Wooddeholm Co., Ltd.) and having no surface treatment such as plating or fluororesin coating on the finished surface. The rubber stopper was manufactured by press molding using a vulcanizable butyl rubber composition in a mold at 160 ° C. for 15 minutes. In this mold, 50 rubber stopper female dies are formed. For comparison, a butyl rubber-made rubber stopper was manufactured in the same manner as described above, except that SUS304 was used and a mold having a finish-processed surface subjected to chrome plating was used.

When the mold of the present invention is used, the repetition
No mold dirt is produced at the time of use 00 times,
There was no need for mold cleaning. On the other hand, when the conventional mold is used, about 20% of the total
Then, mold contamination began to occur, and the mold was washed at the time of use 100 times. After the washing, the molding was started again, and the mold was washed 12 times in total during use 1000 times. Since one mold cleaning takes about 10 minutes, a total of about 2 hours was spent for extra mold cleaning.

[0016]

According to the present invention described above, the number of times of mold cleaning can be significantly reduced, so that the productivity in the production of vulcanized rubber products can be significantly improved. Further, as a result of suppressing mold contamination, it is possible to produce a vulcanized rubber product having excellent dimensional accuracy.

Claims (13)

[Claims] 1. A mold for producing a vulcanized rubber product, which is made of a high alloy steel and whose surface after finishing is not subjected to surface treatment such as plating and / or fluororesin coating. 2. The mold for producing a vulcanized rubber product according to claim 1, wherein the high alloy steel is an improved product of SUS420F. 3. The mold for vulcanized rubber product production according to claim 1, wherein the high alloy steel is obtained by adding chromium element to carbon steel. 4. The high alloy steel is RAMA manufactured by Wooddeholm.
The mold for producing a vulcanized rubber product according to claim 3, which is XS (trade name). 5. The mold for producing a vulcanized rubber product according to any one of claims 1 to 4, wherein the vulcanized rubber product is a rubber stopper of a container for medicine, food and cosmetics. 6. A rubber stopper for a pharmaceutical container, a rubber stopper for a vial preparation container, a piston (slider stopper) for a syringe or a rubber stopper for a syringe / container (cap for a needle attachment portion, insertion and sealing at a lower end portion). 6. The mold for producing a vulcanized rubber product according to claim 5, wherein 7. The vulcanized rubber product mold according to claim 5, wherein at least a part of the surface of the vulcanized rubber product is coated with a film of an α-olefin polymer such as polyethylene or a fluoropolymer. . 8. A high alloy which is not subjected to surface treatment such as plating and / or fluororesin coating on a finished surface as a mold when producing a vulcanized rubber product by compression molding, transfer molding or injection molding. A method for producing a vulcanized rubber product, comprising using a steel mold. 9. The method for producing a vulcanized rubber product according to claim 8, wherein the high alloy steel is an improved product of SUS420F. 10. The method for producing a vulcanized rubber product according to claim 8, wherein the high alloy steel is obtained by adding chromium element to carbon steel. 11. A high alloy steel made by Wooddeholm RAM
The method for producing a vulcanized rubber product according to claim 10, which is AXS (trade name). 12. The method for producing a vulcanized rubber product according to claim 8, wherein the vulcanized rubber product is a rubber stopper of a container for pharmaceuticals, foods, and cosmetics. 13. A rubber stopper for a pharmaceutical container may be a rubber stopper for a vial preparation container, a piston (slider stopper) for a syringe or a rubber stopper for a syringe / container (cap for an injection needle attachment portion, insertion and sealing at a lower end portion). The method for producing a vulcanized rubber product according to claim 12, wherein