JPS61118205A - Preventing method of flow of rubber between adjoining rubber components - Google Patents

Abstract

PURPOSE:To prevent flow of inner liner rubber into ply coating rubber by improving green strength, by a method wherein surface treatment of the surface of one side unvulcanized rubber components adjoining to each other is performed by a rubber accelerator through which low temperature or room temperature vulcanization is possible and molding is performed by sticking the components together. CONSTITUTION:At the time of manufacture of a rubber article, surface treat ment of at least the surface of one side out of either the one side or both the sides of unvulcanized rubber components adjoining to each other which are made of at least one kind of rubber selected out of a group consisting of natural rubber and diene series synthetic rubber, and then after particle vulcanization of said surface, press vulcanization is performed by performing molding by sticking these rubber components together. Although this method is suitable for the titled method preventing flow of inner liner rubber of a tire into ply coating rubber, it is not limited only to the method but applied to the method preventing flow of the rubber into a space between various rubber components adjoining each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for preventing flow between adjacent rubber members in a vulcanization process for rubber articles, particularly for preventing the flow of inner liner rubber of a tire into ply coating rubber. 0 (Prior art) Rubber articles, especially those used under harsh conditions such as tires, have different performance requirements for their constituent elements, and each component has its own performance requirements in order to satisfy these requirements. It is not uncommon for individual rubber members to be used in the elements.

However, at the stage of vulcanizing a rubber article made up of a plurality of rubber members, the rubber flows between adjacent rubber members, making it impossible to arrange the rubber member or the reinforcing elements present together with the rubber member in the desired designed structure. was often the case.

In particular, when vulcanizing a tire, the inner liner rubber is subjected to tension as the internal pressure increases due to the pressure applied by the Prada, and at the same time is strongly pressed against the carcass compound, so the inner liner rubber is pushed between the carcass ply cords. As a result, the ply coating rubber may separate from the cord, causing ply separation. In severe cases, the ply cord may be exposed from the inner liner comb, causing failure of the tube bank, ply separation, etc. This reduced the effective thickness of the liner rubber, deteriorating its properties as an air barrier, and was also unfavorable in terms of the inner surface appearance of the tire.

Conventionally, as a method for preventing such rubber flow from the inner liner rubber to the carcass ply rubber, for example, prior to tire molding and vulcanization, the inner liner rubber after sheeting in a calendar is partially vulcanized using radiation such as an electron beam. After that, it is molded and vulcanized.
There are methods described in No. 0, Japanese Patent Application Laid-open No. 49-99776, etc. h Still, rubber flow can be improved by improving the green modulus when unvulcanized, but for that reason,
For example, methods for creating relatively small meshes during unvulcanization are disclosed in Japanese Patent Application Laid-open No. 48-42080 and Japanese Patent Publication No. 47-11895.
It is described in US Pat. No. 8,512,808, etc., and methods for improving green strength by increasing cohesive force are disclosed in Japanese Patent Publication No. 45-831707, Japanese Patent Publication No. 47-18082,
Special Publication No. 47-15702, Japanese Patent Publication No. 16996-1971, Special Publication No. 4-12571! No., Special Publication Showa 48-10685
No., JP-A-49-78790, JP-A-49-? 81
No. 91, Japanese Patent Publication No. 50-67890, Japanese Patent Application Publication No. 51-4
5198, JP 48-1051148, JP 1υ JP 51.28848, JP 58-287, JP 56-141810, JP 58-147811, and U.S. Patent No. 4181658. It will be stated in the statement etc.

In addition, methods for improving green strength through ionic bonding are disclosed in JP-A-50-75685 and JP-A-50.7954.
No. 1, JP-A-51-117842, JP-A-52-11
No. 71141, Japanese Patent Application Laid-Open No. 155652/1983, West German Patent No. 1570304, and the like.

Furthermore, Special Publication No. 34-6538 and Special Publication No. 44-80
No. 990 and Dutch Patent No. 6807047, US Patent No. 4020115 and US Patent No. 89519
A method for improving green strength by increasing the crystallinity of a polymer, as seen in the specification of US Patent No. 86, etc.
8fS8844 specification, JP-A-50-77448,
JP 58-52589, JP 47-11815, JP 48-12071, and U.S. Patent No. 409
A method using polymer entanglement by adding a polymeric component as seen in Japanese Patent Publication No. 41-8782, Japanese Patent Publication No. 41-13!70, and US Pat. No. 4179480, U.S. Patent No. 416828
6, U.S. Pat. No. 4,152,870, etc., or methods using additives, such as Japanese Patent Publication No. 46-40415 and Japanese Patent Publication No. 48
-3900, JP-A-48-102147, JP-A-5
1-109049, JP 47-39147, JP 48-14786, JP 50-51144, JP 54-7450, and U.S. Patent No. 396807
There is a method described in Specification No. 6, etc.

(Problems to be Solved by the Invention) These conventional techniques, for example, involve irradiation with radiation such as electron beams as a means of creating a relatively small network during unvulcanization, which requires a large amount of capital investment to introduce. In addition, methods that utilize ionic bonds require methods such as adding a tertiary amine during polymerization, or polymerizing monomers to which a tertiary amine has been added in advance, and cannot be applied to natural rubber. It has drawbacks such as:

In addition, methods of increasing the crystallinity of the polymer, adding polymer components, or using block polymers may improve the clean strength, but the properties of the matrix will change significantly, which will have a negative impact on the physical properties of the rubber after vulcanization. However, if the green strength is improved, the viscosity of the unvulcanized state increases, except for the above-mentioned method of partially vulcanizing the inner liner rubber with an electron beam.
As a result, there was a drawback that 1, factory workability such as calender workability and extrusion workability was significantly reduced.

That is, there has been no technology for preventing rubber flow between adjacent rubber members due to vulcanization at low cost and without reducing factory workability.

(Means for Solving the Problems) As a result of intensive studies in order to solve the above-mentioned drawbacks, the inventors of the present invention found that in manufacturing a rubber article, at least one surface of an adjacent unvulcanized rubber member is partially vulcanized in advance. As a result, the present invention was achieved by confirming that it was suitable for the above purpose.

That is, the structure of the present invention is that, in manufacturing a rubber article, one or both of adjacent unvulcanized rubber members each made of at least one kind of rubber selected from the group consisting of natural rubber and diene-based synthetic rubber. At least one side of both is surface treated with a vulcanization accelerator that can be vulcanized at low temperature or naturally, and then, after partially vulcanizing the surface, these rubber members are laminated to form dust, and then pressure vulcanized. A method for preventing rubber flow between adjacent rubber members.

In the present invention, natural rubber and diene-based synthetic rubber are used as the rubber constituting the rubber member. Diene-based synthetic rubber includes synthetic polyisoprene rubber, polybutadiene rubber,
Examples include styrene-butadiene rubber, acrylonitrile-butadiene rubber, and ethylene-propylene terpolymer rubber.1 These may be used alone or in a blend.

The vulcanization accelerators that can be vulcanized at low temperatures or naturally used in the present invention include tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram tetrasulfide, dipentamethylenethiuram hexasulfide, and diethyldithiocarbamic acid. sodium, di-n-
Fium butyldithiocarbamate, potassium di-n-butyldithiocarbamate, zinc di-n-butyldithiocarbamate, zinc dimethyldithiocarbamate, complex salt of zinc dibutyldithiocarbamate and diptylamine, zinc dimethylpentamethylenedithiocarbamate, ethyl/L/ Zinc phenyldithiocarbamate 1 complex zinc salt of dithiocarbamic acid, diethylamine diethyldithiocarbamate 1 N,N-dimethylcyclohexamine salt of diptyldithiocarbamate, piperidine pentamethylene dithiocarbamate, bipefrine pentamethylene dithiocarbamate, activated dithiocarbamate, isopropyl xanthogen These are sodium acid, zinc isopropylxanthate, zinc ethylxanthate, or zinc butylxanthate, and these may be used alone or in combination.

In the present invention, the above-mentioned vulcanization accelerator is applied to at least one surface of one or both of adjacent unvulcanized rubber members by coating or dipping, and the treated surface is partially vulcanized. is preferably applied to one or both surfaces of the unvulcanized rubber member to be adjoined, and after partial vulcanization,
Laminate and mold and pressure vulcanize. In addition, the methods for applying these vulcanization accelerators to the rubber surface include liquid ones such as sodium 1-n-butyldithiocarpamate and potassium di-n-butyldithiocarbamate, or other solid forms. As well as acetone, ethanol,
Dissolve it in a suitable solvent such as chloroform or rubber mq oil at an appropriate concentration and apply it to the rubber surface using a brush or roll, spray S, or immerse it in a solution containing a vulcanization accelerator. The method of doing so is used, but
Any other method may be used as long as it does not impair the purpose of the present invention. In addition, after applying the vulcanization accelerator and before bonding, it is necessary to leave it for partial vulcanization, but if you perform heat treatment at a temperature of about 50 to 12,080 degrees, you can shorten the leaving time and also It is also possible to reduce variations in the degree of partial vulcanization due to changes in temperature.

The method of the present invention is suitable as a method for preventing the tire inner liner rubber from flowing into the ply coating rubber, as shown in the following examples, but the present invention is not limited to this only, and can be used in various ways. It is applied to prevent rubber from flowing between adjacent rubber members, such as between the tread rubber member and carcass of a tire, the rubber member of the sidewall part, or between multilayer rubber hoses or vibration-proof rubber members. and achieve equally favorable results.

(Example) Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Examples 1 and 2 Comparative Example 1 This will be explained with reference to FIG. 1 showing the inner side of a part of the tire shoulder. The tread and sidewall parts are made of a commonly used rubber composition, the carcass and belt are made of steel cord 1, and the number of carcass plies is 28.
A green tire was prepared using a rubber composition having the composition shown in Table 1 as inner liner rubber 8 and ply coating rubber 2 for the 10G0R20114PH truck/pass radial tire, which is a 1/60 parrot. Vulcanized by At this time, a low-temperature vulcanization accelerator [tetrabutylthiuram disulfide (TBT), di-n-butyldithiocarbamine sodium (TP)] was applied to the surface of the inner liner rubber 8 (thickness 4 pieces) adjacent to the carcass ply. At a concentration of 50% by weight, TBT was dissolved in rubber volatile oil and TP was dissolved in Edano I and applied, the solvent was air dried, heat treatment was performed at 100 °C for 90 minutes, and the green modulus at 80 °C was measured. I used it after my bowel movements. In this example, heat treatment was performed to shorten the period required for the evaluation test, but equivalent vulcanization and hardening can be obtained by discharging at room temperature for a certain period of time without heating. Next, the inner liner gauge (gauge L shown in Figure 1) of the shoulder part of the above radial tire for trucks and buses (the gauge becomes thinner even after vulcanization) was cured at 155°C for 60 minutes.・UNIT PROOESS A
Non-Destructive Coating Thickness Tester (NON-) manufactured by SSEMBLES INO,
DESTRUOTIVE C0ATINGTHIciK
NEss TESTJiR) Dermitron D
-9, measurements were taken at four locations on the tire circumference. Furthermore, as a comparative example, a tire to which no vulcanization accelerator was applied was also evaluated in the same manner. The results are shown in Table 2.

Table 1 Part by weight Natural rubber 90IR
220010 HAF carbon black
50 aroma oil
2 Zinc oxide.

N-oxydiethylene-2-benzothiazolesulfenamide 0.5 sulfur
5 Table 2 As is clear from Table 2, in the method according to the present invention, the inner liner gauge after vulcanization is more than twice as thick as that of Comparative Example 1, and there are fewer variations, and the inner liner gauge 8 has a smaller thickness. The flow into the rubber band 2 is significantly improved.

The squares in Table 2 represent the average value, and the standard deviation value.

(Effects of the Invention) As explained above in the Examples and Comparative Examples, the method of the present invention is capable of promoting vulcanization that allows at least one surface of one or both of adjacent unvulcanized rubber members to be vulcanized at low temperature or naturally. By treating the surface with a chemical agent, then partially vulcanizing the surface, and then bonding and molding these rubber members, factory workability is good, green strength is improved, and the inner liner gauge after vulcanization is It can be seen that the inner liner rubber is more than twice as thick as the conventional example, and there is less variation in thickness, and that the flow of the inner liner rubber into the ply footing rubber is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of essential parts showing the inner side of a part of the tire shoulder. 1...Carcass ply cord 2...Carcass splicing rubber 8...Inner liner

Claims (1)

[Claims] 1. In manufacturing a rubber article, at least one or both of adjacent unvulcanized rubber members each made of at least one kind of rubber selected from the group consisting of natural rubber and diene-based synthetic rubber. It is characterized by treating one side with a vulcanization accelerator that can be vulcanized at low temperature or naturally, and then partially vulcanizing the surface, and then bonding these rubber members together, molding them, and vulcanizing them under pressure. A method for preventing rubber flow between adjacent rubber members. 2. Vulcanization accelerators that can be vulcanized at low temperatures or naturally include tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram tetrasulfide, dipentamethylenethiuram hexasulfide, sodium diethyldithiocarbamate, di-n -Sodium butyldithiocarbamate, potassium di-n-butyldithiocarbamate, zinc di-n-butyldithiocarbamate, zinc dimethyldithiocarbamate, complex salt of zinc dibutyldithiocarbamate and dibutylamine, zinc dimethylpentamethylenedithiocarbamate, ethylphenyldithiocarbamic acid Zinc, complex zinc salt of dithiocarbamate, diethylamine diethyldithiocarbamate, N,N-dimethylcyclohexamine salt of dibutyldithiocarbamate, piperidine pentamethylenedithiocarbamate, pipecoline pentamethylenedithiocarbamate, activated dithiocarbamate, sodium isopropyl xanthate, isopropyl The method according to claim 1, wherein the method is at least one selected from the group consisting of zinc xanthate, zinc ethylxanthate, and zinc butylxanthate.