JP2006137048A - Vulcanized rubber molded product, weather strip and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vulcanized rubber molded product suppressed in the occurrence of an aromatic organic compound or the occurrence of an unpleasant smell, a weather strip being one kind of the vulcanized rubber molded product and suppressed in the occurrence of the unpleasant smell estimated to be caused by a chemical foaming agent and its manufacturing method. <P>SOLUTION: The vulcanized rubber molded product contains a thiosulfate and the weather strip being the vulcanized rubber molded product includes a vulcanized rubber foam molded part containing the thiosulfate. The content of the thiosulfate is preferably 0.1-3.0 wt.%. The manufacturing method of the weather strip has an extrusion process for extruding a foamable unvulcanized rubber composition containing a foaming agent from the die having a predetermined shape of an extruder to mold an unvulcanized molded product and a vulcanization process for heating and vulcanizing the unvulcanized molded product to form the weather strip being the vulcanized rubber molded product comprising a vulcanized rubber foam. The foamable unvulcanized rubber composition contains the thiosulfate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vulcanized rubber molded body, an automotive weather strip which is a vulcanized rubber molded body, and a method for producing the same.

  In the production of vulcanized rubber moldings, raw rubber, reinforcing agents such as carbon black and silica, unvulcanized rubber composition containing sulfur and vulcanization accelerator for vulcanization in addition to process oil and 160 ° C. It is heated and vulcanized at a higher temperature. At this time, aromatic hydrocarbons such as toluene and xylene, which are presumed to be slightly contained in the process oil as volatile organic compounds, are volatilized and are not preferable in the working environment, and their reduction is required. Further, the vulcanized rubber molded article has a specific odor based on the reaction of sulfur or a vulcanization accelerator, and reduction of these odors is also required.

  A weatherstrip, which is a type of vulcanized rubber molded body, is composed of a vulcanized rubber foam or a combination of a vulcanized rubber foam molded part and a solid rubber molded part, and is used for automobile doors, trunks. It is widely used as a seal member that seals between a body part and an opening and closing member such as a door in a sunroof part. As raw materials for vulcanized rubber foams such as weather strips, in addition to the above components, nitroso-based foaming agents, azodicarbonamide-based foaming agents and the like are blended and used in unvulcanized rubber compositions (Patent Document 1, etc.) ).

These foaming agents for vulcanized rubber moldings generate nitrogen as a foaming gas, but reaction by-products having an unpleasant odor presumed to be slightly derived from the nitrogen of the foaming agent in the vulcanized rubber foam. Remains. Until now, the odor of the vulcanized rubber constituting the weather strip has not been considered a problem, but in recent years, the odor of the vulcanized rubber has been required to be reduced while seeking a more comfortable automobile. .
JP-A-7-33896

  In view of the above-mentioned demands, the present invention is a vulcanized rubber molded product in which generation of an aromatic organic compound and unpleasant odor are suppressed, and a vulcanized rubber molded product, which are presumed to be caused by a chemical foaming agent. An object of the present invention is to provide a weather strip in which the generation of unpleasant odor is suppressed and a method for manufacturing the weather strip.

  The vulcanized rubber molded article of the present invention is characterized by containing a thiosulfate.

  The vulcanized rubber molded body having such a structure has reduced generation of aromatic hydrocarbons such as toluene and xylene, which are volatile organic compounds generated during vulcanization, and is effective in reacting sulfur and vulcanization accelerators. The specific odor based on it is also reduced. In addition, when the vulcanized rubber molded body is a vulcanized rubber foam, unpleasant odor considered to be caused by the foaming agent is suppressed. The reason why the addition of thiosulfate suppresses or eliminates aromatic hydrocarbon volatilization and unpleasant odor is not clear. The vulcanized rubber molded body may be a solid rubber, a vulcanized rubber foam, or a solid rubber portion and a vulcanized rubber foam molded portion.

  In the above vulcanized rubber molded article, the content of the thiosulfate is preferably 0.1 to 3.0% by weight.

  When the content of thiosulfate is less than 0.1% by weight in the vulcanized rubber molding material, the effect of addition may not be sufficiently exhibited. When the content exceeds 3.0% by weight, thiosulfate particles Since it itself does not have any reinforcing properties, it may become a foreign substance and may adversely affect the physical properties of the vulcanized rubber molded body.

  The weather strip of the present invention is a vulcanized rubber molded product including a vulcanized rubber foam molded part, and contains a thiosulfate.

  The weather strip having such a configuration is preferable in terms of manufacturing work environment because volatile organic compounds such as toluene and xylene, which are presumed to be caused by process oil added to the raw unvulcanized rubber composition, are reduced. Also, unpleasant odors presumed to be caused by nitrogen-containing compounds that are decomposition by-products of the foaming agent used to form vulcanized foam rubber molded parts, and unpleasant odors caused by sulfur compounds in solid rubber foam parts or foam rubber molded parts Odor is suppressed or removed. The reason why the unpleasant odor is suppressed or eliminated by the addition of thiosulfate is not clear.

  In the above-described weather strip, the content of the thiosulfate is preferably 0.1 to 3.0% by weight.

  When the content of thiosulfate is less than 0.1% by weight in the weatherstrip constituent material, the effect of addition may not be sufficiently exhibited. When the content of thiosulfate exceeds 3.0% by weight, the thiosulfate particles themselves do not have any effect. Since it does not have reinforcement, it may become a foreign substance and affect the physical properties of the weather strip.

The method for producing a weather strip according to the present invention includes an extrusion step of extruding a foamed unvulcanized rubber composition containing a foaming agent from a die having a predetermined shape with an extruder to obtain an unvulcanized molded body, and the unvulcanized molded body It has a vulcanization step of heat vulcanizing and forming a weather strip which is a vulcanized rubber molded body made of a vulcanized rubber foam,
The foamed unvulcanized rubber composition contains a thiosulfate.

  By the manufacturing method having such a configuration, generation of aromatic hydrocarbons in the vulcanized rubber foam molded part, unpleasant odor due to sulfur, vulcanization accelerator, etc. are suppressed, and further, a nitrogen-containing compound which is a decomposition byproduct of the foaming agent Therefore, it is possible to produce a weather strip that suppresses or eliminates the unpleasant odor estimated to be.

In the above-mentioned weather strip manufacturing method, the extruding step further supplies a non-foamed unvulcanized rubber composition containing no foaming agent to the die by a second extruder, and the foamed unvulcanized rubber composition. And the vulcanization step is a weather strip which is a vulcanized rubber molded body having a vulcanized rubber foam molded part and a solid rubber molded part,
The non-foamed unvulcanized rubber composition contains a thiosulfate.

  In the weather strip having the vulcanized rubber foam molded part and the solid rubber molded part, the aromatic hydrocarbon generated from the solid rubber molded part is further suppressed by the manufacturing method having such a configuration, and the vulcanizing agent and the vulcanization accelerator are suppressed. The unpleasant odor caused by the is also suppressed or eliminated.

  In the weatherstrip manufacturing method described above, the thiosulfate content is preferably 0.1 to 3.0% by weight.

   As the rubber material constituting the weather strip of the present invention, any known rubber material can be used without limitation in both vulcanized rubber foam and solid rubber. Specifically, as the weather strip rubber material, EPDM, polychloroprene rubber and the like are preferable from the viewpoint of weather resistance.

  The weather strip, which is a vulcanized rubber molded body, may be composed only of a vulcanized rubber foam, or may be a structure in which a vulcanized rubber foam part and a solid rubber part are integrated.

  Examples of foaming agents that form vulcanized rubber foams include inorganic foaming agents such as sodium bicarbonate, nitroso compounds such as N, N′-dinitrosopentamethylenetetramine, azodicarbonamide compounds such as azodicarbonamide, and benzenesulfonyl. Examples include sulfonyl hydrazides such as hydrazide, p-toluenesulfonyl semicarbazide, and the like, and salicylic acid, urea, and a foaming aid containing these are added as necessary.

  In addition to the above rubber materials, vulcanized rubber foams and solid rubbers are supplemented with reinforcing agents such as carbon black and silica, process oils and plasticizers, and are further filled with fillers, ozone degradation inhibitors, anti-aging agents, and processing aids. Add agents as necessary.

  The thiosulfate used in the present invention is preferably an alkali metal salt of thiosulfate, more preferably sodium thiosulfate or potassium thiosulfate. The thiosulfate is preferably kneaded as a fine powder and added to the unvulcanized rubber composition.

  A method for producing a weather strip, which is an example of a vulcanized rubber molded body, is according to a known method exemplified below.

1) Preparation of unvulcanized rubber composition Preparation of a foamed unvulcanized rubber composition for forming a vulcanized rubber foam is carried out by first kneading a rubber material with ingredients other than a vulcanization accelerator, a vulcanizing agent, a foaming agent, and a foaming aid by a Banbury mixer. Make a batch. After the obtained master batch is cooled, a vulcanization accelerator, a vulcanizing agent, a foaming agent and a foaming aid are added to the master batch using a kneading roll or kneader and kneaded to form an unvulcanized rubber composition for foaming. It is a thing.
B. The preparation of a non-foamed unvulcanized rubber composition used for the production of a weatherstrip composed of a vulcanized rubber foam molded part and a solid rubber part is the same as described above without adding a foaming agent and a foaming aid. Perform by operation. In preparing the non-foamed unvulcanized rubber composition, it is preferable to add a thiosulfate as in the foamed unvulcanized rubber composition.

2) Extrusion process The unvulcanized rubber composition is supplied to an extruder equipped with a die for extruding an unvulcanized molded body having a predetermined shape and extruded into a continuous strip shape. In the production of a weather strip having a vulcanized rubber foam part and a solid rubber part, two extruders, an extruder for extruding an unvulcanized rubber composition for foaming and an extruder for extruding an unvulcanized rubber composition for solid Are connected to one die and extruded by coextrusion.

3) Vulcanization process A continuous strip-shaped unvulcanized molded body extruded from an extruder is heated, vulcanized and foamed to form a continuous weather strip. The obtained weather strip is subjected to surface coating as necessary, and cut into a final shape.

  In processing to the final shape, corner portions and the like may be molded, but it is a preferable aspect that thiosulfate is also added to the rubber material constituting the molded portion.

  In the case of a vulcanized rubber molded body made of solid rubber, it can be produced by a press molding method, an injection molding method, a transfer molding method or the like in addition to the above-described extrusion molding. An injection molding method or the like can also be used to form a molded part for connecting a weather strip which is a vulcanized rubber foam and is extruded.

Example 1
100 parts by weight of ethylene propylene rubber (Sumitomo Chemical), 100 parts by weight of carbon black (Tokai Carbon), 65 parts by weight of process oil (Idemitsu), 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 10 parts by weight of white filler, processing 1 part by weight of auxiliary agent, 2 parts by weight of calcium oxide, 2 parts by weight of foaming agent OBSH, 5 parts by weight of vulcanization accelerator, 1 part by weight of sulfur and sodium thiosulfate are 0.1% by weight in the unvulcanized rubber composition. And kneaded by the above method to prepare an unvulcanized rubber composition for foaming.

  The unvulcanized rubber composition is supplied to an extruder to obtain an unvulcanized molded body, which is heated and vulcanized at 200 ° C. for 10 minutes to obtain a cylindrical evaluation foam having an outer diameter of 30 mm and an inner diameter of 20 mm. Obtained.

(Example 2)
A foam for evaluation was produced in the same manner as in Example 1 except that the amount of sodium thiosulfate added was 2.0% by weight in the unvulcanized rubber composition.

(Example 3)
A foam for evaluation was produced in the same manner as in Example 1 except that the amount of sodium thiosulfate added was 3.0% by weight in the unvulcanized rubber composition.

(Comparative Example 1)
A foam for evaluation was produced in the same manner as in Example 1 except that sodium thiosulfate was not added.

<Evaluation>
(Aromatic hydrocarbon)
A sample is cut out to obtain an evaluation sample so that the surface area becomes 100 cm ² . This evaluation sample is enclosed in a 4 L capacity Tedlar bag and heated in a hot air dryer at 60 ° C. for 2 hours. Next, the gas in the Tedlar bag is sucked by a pump, and volatile organic substances in the gas are adsorbed on a predetermined adsorption tube. The adsorption tube was connected to a gas chromatograph, and toluene and xylene in the adsorbed volatile organic compound were quantitatively analyzed. The measurement results are shown in Table 1.
(Odor)
A test sample having a length of 100 mm was cut out from the evaluation foam in the form of a continuous strip, placed in a commercially available sampling bag for collecting a gas sample, and heated at 60 ° C. for 2 hours. The odor was evaluated with a monitor after the sampling bag was cooled to room temperature. The results are also shown in Table 1.

この表の結果より、本発明の加硫ゴム成形体であるウェザーストリップは芳香族炭化水素の発生量が効果的に抑制されていることが分かる。また不快臭も抑制されていることが明らかである。

From the results in this table, it can be seen that the weather strip, which is the vulcanized rubber molded body of the present invention, effectively suppresses the amount of aromatic hydrocarbons generated. It is clear that unpleasant odor is also suppressed.

Claims (7)

  A vulcanized rubber molded article containing a thiosulfate.   The vulcanized rubber molded article according to claim 1, wherein the thiosulfate content is 0.1 to 3.0 wt%.   A weatherstrip, which is a vulcanized rubber molded product including a vulcanized rubber foam molded part and contains thiosulfate.   The weather strip according to claim 3, wherein a content of the thiosulfate is 0.1 to 3.0% by weight in the vulcanized rubber molded body. An extruding step in which a foamed unvulcanized rubber composition containing a foaming agent is extruded from a die having a predetermined shape by an extruder to form an unvulcanized molded body, and the unvulcanized molded body is heated and vulcanized to obtain a vulcanized rubber foam. A vulcanization process comprising a weather strip that is a vulcanized rubber molded body comprising:
A method for producing a weather strip, wherein the foamed unvulcanized rubber composition contains a thiosulfate. The extruding step further comprises supplying a non-foamed unvulcanized rubber composition containing no foaming agent to the die with a second extruder and coextruding the foamed unvulcanized rubber composition. The vulcanization process is a weather strip which is a vulcanized rubber molded body having a vulcanized rubber foam molded part and a solid rubber molded part,
The method for producing a weather strip according to claim 5, wherein the non-foamed unvulcanized rubber composition contains a thiosulfate. The method for producing a weather strip according to claim 5 or 6, wherein the content of the thiosulfate is 0.1 to 3.0% by weight.