JPS6361969B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubber composition containing halogenated butyl rubber, and more specifically, the present invention relates to a rubber composition containing halogenated butyl rubber, and more specifically, a halogenated butyl rubber composition that has improved adhesion after co-vulcanization with a rubber composition containing the same or different type of rubber by incorporating a petroleum resin. The present invention relates to a rubber composition containing fluorinated butyl rubber. Tires and industrial rubber products are made by laminating many rubber compositions together during the manufacturing process, especially the molding process. Therefore, the adhesion between rubber compositions after vulcanization (hereinafter referred to as rubber/rubber adhesion) is of greatest concern to the rubber industry. In particular, in order to satisfy the strict quality requirements from users these days, it is often necessary to rely on the introduction of new polymers, that is, raw material rubber. However, it is often difficult to introduce rubber compositions using new polymers because of their insufficient rubber/rubber adhesion. Examples include rubber compositions containing halogenated butyl rubber. Halogenated butyl rubber is a version of butyl rubber with improved vulcanizability.It has the characteristics of conventional butyl rubber, such as excellent gas impermeability and excellent weather resistance, but has also been made possible to blend with general-purpose diene rubber. , which increases the vulcanization rate by adding halogen atoms to the butyl rubber side chains. Therefore, its skeleton has fewer unsaturated bonds than general-purpose rubbers, and it belongs to the so-called low unsaturated rubber category. Therefore, despite the excellent characteristics mentioned above, there are problems with co-vulcanization with general-purpose diene rubbers, and as a result, rubber/rubber adhesion, which is an important property required in the production of rubber products, is poor. It becomes very inferior. In particular, adhesion between rubber compositions containing halogenated butyl rubber and rubber compositions containing natural rubber, styrene-butadiene rubber, isoprene rubber, or butadiene rubber after vulcanization is extremely difficult, causing many problems in product performance. . For example, rubber may peel off due to poor adhesion with different rubbers. Conventionally, as a means to solve this kind of problem, a rubber composition was dissolved in an organic solvent and applied to the rubber surface, or an appropriate vulcanization accelerator was added to the rubber composition in order to bring the vulcanization speed of different rubbers closer together. In some cases, adhesive resins such as alkylphenol resins are added. However, such methods do not give sufficiently satisfactory results, and in particular, rubber compositions containing different rubbers, especially low unsaturated rubber compositions such as halogenated butyl rubber, natural rubber, styrene rubber, etc. Adhesion with unsaturated rubber compositions such as butadiene rubber, isoprene rubber, and butadiene rubber is extremely difficult, and sufficient effects have not been obtained. The reason for this is thought to be that these adherends and the base material of the rubber paste or the adherends have different polarities and a difference in vulcanization rate. Furthermore, it is generally said that asphalt is suitable for improving the rubber/rubber adhesion between a rubber composition containing halogenated butyl rubber and a rubber composition containing a different rubber. It is true that the addition of asphalt has better adhesive strength than the methods described above, in which a rubber composition is dissolved in an organic solvent and applied to the rubber surface, or a suitable vulcanization accelerator or adhesive resin is added to the rubber composition. Although this is an excellent method in terms of level, it is well known that asphalt is often viscous at room temperature, has a strong odor, and is extremely difficult to work on site. As described above, in the conventional methods, there is still no method that satisfies the adhesion after vulcanization between a rubber composition containing a halogenated butyl rubber and a rubber composition containing a different rubber such as a diene rubber, including processability. It is no exaggeration to say that it has not been done. The present invention improves adhesion after vulcanization with other diene rubber compositions, which has traditionally been a problem in the production of rubber products, and also contains halogenated butyl rubber, which has excellent processability. The present invention aims to provide a rubber composition that is widely used in automobile tires, rubber articles, rubber footwear, etc., and is particularly suitable for tire sidewalls, inner liners, and treads. The present inventors have discovered that the above object can be achieved by adding a specific resin to a rubber composition containing halogenated butyl rubber, and have arrived at the present invention. The present invention comprises at least 10 halogenated butyl rubbers.
This rubber composition is characterized in that 10 to 30 parts by weight of a petroleum resin having a softening point of 80 to 120°C and a fixed carbon content of 25 to 50% is blended to 100 parts by weight of raw rubber. The term "halogenated butyl rubber" as used in the present invention refers to rubber in which a halogen atom such as chlorine or bromine is added to a butyl rubber side chain. It is necessary that the halogenated butyl rubber is contained in the raw material rubber in an amount of 10% by weight or more.
If the halogenated butyl rubber is less than 10% by weight, the adhesion after vulcanization with other diene rubber-containing rubber compositions will not be a problem, but the gas impermeability or weather resistance of the halogenated butyl rubber will not be a problem. This characteristic cannot be obtained either. Halogenated butyl rubber may be blended alone or in combination with other raw material rubbers. As the other raw material rubber, at least one of natural rubber and diene-based synthetic rubber is appropriately selected depending on the use of the rubber composition, and the blending amount thereof is 90% or less in the raw material rubber. The petroleum resin used in the present invention consists of a fraction rich in aromatic components extracted from a petroleum fraction (average molecular weight 200 to 800) with furfural, phenol, and other appropriate solvents and an oxygen-containing gas or a gas containing oxygen and ozone. It is a resin compound obtained by catalytic reaction of
%, and an aromatic index of 0.68 or more, and a petroleum resin within this range improves the adhesion of the halogenated butyl rubber-containing rubber composition to other diene-based rubber-containing rubber compositions after vulcanization. The amount of petroleum resin added in the present invention is 10 to 30 parts by weight per 100 parts by weight of raw rubber. If it is less than 10 parts by weight, the adhesion with rubber compositions containing other diene rubbers will be poor and interfacial peeling will occur. arise. If it exceeds 30 parts by weight, the vulcanized physical properties, especially the tensile strength, will decrease, resulting in a decrease in adhesive strength. In the rubber composition of the present invention, compounding agents normally used in the rubber industry, such as carbon black, zinc oxide, stearic acid, extender oil, vulcanization accelerator, and sulfur, are blended in appropriate amounts depending on the intended use. The present invention will be specifically described below based on Examples and Comparative Examples. Note that the blending values in the table are parts by weight. Examples 1 to 2 and Comparative Examples 1 to 4 Commercially available brominated butyl rubber was used as a raw material rubber at the compounding ratio shown in Table 1, and a vulcanization accelerator and compounding agents other than sulfur, as well as various resins or petrolatum were added. The mixture was kneaded for 4 minutes using a B-type Banbury mixer (capacity: about 1.5), a vulcanization accelerator and sulfur were added thereto, and kneaded for 5 minutes using an 8-inch roll to obtain a rubber composition. This rubber composition and a rubber composition using natural rubber as the raw material were laminated together at 160°C.
Press co-vulcanization was performed for 30 minutes and a rubber/rubber adhesion test was performed. This rubber/rubber adhesion test is JIS
Made in accordance with K6301, width 25.0±0.5mm, length 150mm, thickness 6mm with reinforcing material laminated on both sides.
Perform a 180° peel test on a strip-shaped test piece using an autograph at a pulling speed of 50 mm/min, then calculate the average value of each peak (high value) of the wavy part of the tensile load curve, and calculate this as the peel strength. It was expressed as an index with the value of Comparative Example 3 as 100. Furthermore, the state of rubber failure was expressed as a ratio of interface failure (%)/material failure (%). The results are shown in Table 1. Further, Table 2 shows the formulation of a rubber composition using the bonded natural rubber as a raw material rubber.

[Table] As shown in Table 1, Examples 1 to 2 in which petroleum resin was added are comparative examples 1 to 4 in which petrolatum, alkylphenol resin, C ₉ resin, and C ₅ resin were added.
It has a higher adhesive strength and a higher rate of material destruction than . This shows that Examples 1 and 2 have good adhesion with other rubber compositions after vulcanization.

【table】

[Table] Examples 3 to 4 and Comparative Examples 5 to 8 Rubber compositions were obtained under the same conditions as Example 1 using chlorinated butyl rubber with the formulation shown in Table 3, and co-added with the rubber composition shown in Table 2. The resulting vulcanized rubber was subjected to a rubber/rubber adhesion test, and the results are shown in Table 3. Note that the adhesive strength was expressed as an index with Comparative Example 7 set as 100.

[Table] Examples 3 to 4 in which petroleum resin was added even though chlorinated butyl rubber was used as the raw material rubber as shown in Table 3.
Compared to Comparative Examples 5 to 8 in which other resins or petrolatum were added, the adhesive force was higher and the rate of material destruction was higher. Examples 5 to 6 and Comparative Examples 9 to 10 Rubber compositions were obtained under the same conditions as Example 1 with the formulations shown in Table 4, and laminated and co-vulcanized with the rubber compositions shown in Table 2. A rubber/rubber adhesion test was conducted on the vulcanized rubber, and the results are shown in Table 3. Note that the adhesive strength was expressed as an index with Comparative Example 9 set as 100.

【table】

[Table] As is clear from Table 4, Examples 5 to 6 in which petroleum resin was added had superior adhesive strength and a higher rate of material failure than Comparative Examples 9 to 10 in which straight asphalt or blown asphalt was added. It also has excellent workability. Examples 7 to 11 and Comparative Example 11 Rubber compositions were obtained by kneading the formulations shown in Table 5 under the same conditions as in Example 1.
The physical properties of the vulcanized rubber obtained by press vulcanization for 45 minutes were evaluated. Vulcanized physical properties were evaluated in accordance with JIS K6301, and tensile strength, elongation, hardness (JIS) and tear force (using test piece B) were measured. 5th result
Shown in the table. In addition, the rubber composition having the formulation shown in Table 5 was laminated with the rubber composition shown in Table 2, co-vulcanization was performed in the same manner as in Example 1, and the rubber/rubber adhesion test of the obtained vulcanized rubber was conducted. The results are shown in Table 5. Further, this vulcanized rubber was left in an oven at 100°C for 48 hours, and then a heat aging rubber/rubber adhesion test was conducted to evaluate heat aging properties. The results are also shown in Table 5.

【table】

[Table] From Table 5, as the amount of petroleum resin is increased, the adhesive strength improves, and in the fracture state, interfacial peeling decreases and material peeling increases. However, when the petroleum resin is around 30 parts by weight, the adhesive strength decreases. This is considered to be due to the fact that the physical properties of the vulcanizate, especially the tensile strength, decrease as the amount of petroleum resin increases. Similar results were also obtained in the heat aging resistant adhesion test. This shows that the amount of petroleum resin added is preferably 10 to 30 parts by weight per 100 parts by weight of raw rubber. Examples 12 to 15 Rubber compositions were obtained under the same conditions as in Example 1 with the formulations shown in Table 6, and this rubber composition and the rubber compositions in Table 2 were laminated together and co-vulcanized to produce vulcanized rubber. I got it. The obtained vulcanized rubber was subjected to an adhesion test, and the results are shown in Table 6.

[Table] From Table 6, rubber compositions containing petroleum resin using brominated butyl rubber/natural rubber as the raw material rubber are natural when co-vulcanized with rubber compositions using natural rubber in Table 2 as the raw material rubber It has excellent adhesion to rubber, and the main cause of adhesive failure is material failure.
The reason why the higher the content of natural rubber is, the better the adhesion is is thought to be due to the affinity with similar rubbers. As explained above, by adding a certain amount of petroleum resin to a rubber composition made of halogenated butyl rubber alone or mixed with other rubbers,
Adhesion after vulcanization with rubber compositions containing different rubbers can be improved to a level that could not be achieved by conventional methods. Moreover, since the petroleum resin used in the present invention is a lumpy solid at room temperature, it is very easy to handle and does not cause processing problems like asphalt. Therefore, the rubber composition of the present invention can be used in areas where a rubber composition containing halogenated butyl rubber is used and where adhesion with a rubber composition containing a different type of rubber is required, such as tire inner liners, treads, sidewalls, etc. If this is done, since the adhesion after vulcanization is good, there is no risk of rubber peeling while the tire is running, unlike in the past, and this can contribute to improving the variety of tires.

Claims (1)

[Claims] 1 Softening point 80-120 for 100 parts by weight of raw rubber containing at least 10 parts by weight of halogenated butyl rubber
10-30℃, petroleum resin with fixed carbon content 25-50%
A rubber composition characterized in that it contains parts by weight.