JPS61243843A - Rubber composition - Google Patents

Abstract

PURPOSE:To obtain a rubber compsn. which has excellent moldability and is free from bleeding and migration when vulcanized, consisting of a butyl rubber and a hydrogenated liquid diene rubber having a specified iodine value. CONSTITUTION:A rubber compsn. consists of a butyl rubber (a) and a hydrogenated liquid diene rubber (b) having an iodine value of 10-250. Preferred examples of the liquid diene rubbers are liquid isoprene rubbers such as liquid polyisoprene rubber, liquid isoprene/butadiene copolymer rubber, liquid isoprene/ styrene copolymer rubber and liquid isoprene/arcylonitrile copolymer rubber. Pref. the liquid diene rubber has an average MW of 6,000-100,000.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rubber composition comprising a hydrogenated product of butyl rubber and liquid diene rubber.

[Conventional technology]

Butyl rubber has excellent gas impermeability, heat resistance, and electrical insulation properties. Taking advantage of these properties, it is used in tubes or inner liners for automobile or bicycle tires, waterproof sheets for civil engineering and construction, sealants, belts, hoses, etc. These products are manufactured by kneading butyl rubber and rubber compounding chemicals using an open roll or Banbury mixer, then molding by calendering, extrusion, pressing, etc., and then vulcanizing. In this case, workability during kneading, fluidity during molding, and other processability determine the appearance and performance of the resulting product, and have a large impact on productivity such as product yield.

[Problems to be solved by the invention] However, butyl rubber cannot be said to have excellent moldability. Therefore, when the rubber is subjected to roll kneading, the rubber tends to stick to the rolls, making it difficult to cut back and add fillers that are usually mixed into rubber compositions, and to cause cross-contact in the Banbury mixer. If it is used, it becomes difficult to disperse the filler uniformly in a short period of time, and furthermore, it becomes difficult to discharge the compound, which causes disadvantages. Furthermore, the resulting blend does not necessarily have sufficient fluidity. Therefore,
When subjected to calendering, a sheet with a smooth surface cannot be obtained. Furthermore, when extrusion molding is performed, the extrusion speed cannot be increased, and a molded product having a desired shape cannot be obtained. In order to improve the poor moldability of butyl rubber, it has traditionally been necessary to blend a softener such as process oil, or to blend a solid diene rubber such as natural rubber or styrene-butadiene copolymer rubber. Although these methods have generally achieved the above objectives, new problems have arisen. For example, when butyl rubber is blended with a process oil softener, the softener may bleed and migrate, resulting in poor adhesion to other molded products and roughness when bonded to other molded products in an unfluidized state. When the bonded parts are vulcanized and bonded, there are problems such as poor adhesion at the adhesive interface, and even if vulcanized, the softening agent contaminates other parts that are used in contact with it. It is easily extracted by chemical agents, and there is a risk of volatilization and deterioration when heated, reducing the aging resistance of the physical properties of rubber products.Also, when solid diene rubber is blended, one of the excellent characteristics of butyl rubber Not only does the gas permeability decrease, but also the co-vulcanization of butyl rubber and solid diene rubber is not necessarily sufficient, resulting in a decrease in the modulus, breaking strength, and elongation of the vulcanizate obtained. Physical properties deteriorate.

In view of the current situation, the present invention has excellent moldability, no bleed during vulcanization or migration, and excellent aging resistance, modulus, breaking strength, etc. As a result of intensive studies aimed at providing a rubber composition that provides a vulcanizate with improved physical properties, the present invention has been completed.

[Failure to solve the problem]

According to the present invention, the above object is obtained by hydrogenating butyl rubber (a) and liquid diene rubber.
Achieved by a rubber composition consisting of hydrogenated compound (b) of 250 11. Ru.

The butyl rubber used in the present invention is a copolymer of inbutylene and isoprene or a halide thereof, which is commonly used in the rubber industry.

The liquid diene rubber used as a raw material for the hydrogenation product used in the present invention is a polymer of a conjugated diene such as butadiene, isoprene, or pentadiene, or a copolymer thereof, or a polymer of these conjugated dienes and a polymer such as styrene or acrylonitrile. It is a copolymer of a vinyl compound (a vinyl compound that can be copolymerized with a conjugated diene) and has low molecular weight and exhibits fluidity. Specific examples include liquid polyisoprene rubber, liquid polybutadiene rubber, and liquid isoprene rubber. Examples include butadiene copolymer rubber, f-type butadiene-styrene copolymer rubber, liquid imprene-styrene co-M rubber, liquid butadiene-acrylonitrile copolymer rubber, liquid isoprene-acrylonitrile copolymer rubber, and the like. Among these, liquid isoprene rubbers such as liquid polyisoprene rubber, liquid isoprene-butadiene copolymer rubber, liquid isoprene-styrene copolymer rubber, and liquid imprene-acrylonitrile copolymer rubber are preferred. This is because the viscosity of liquid isoprene rubber does not change significantly before and after hydrogenation, and it still exhibits fluidity even after hydrogenation, and the hydrogenated substance improves the moldability of butyl rubber, making it difficult to form compositions with butyl rubber. This is because the strength and elongation properties of the vulcanizate are improved. Particularly preferred are liquid polyimprene rubber and liquid isoprene-butadiene copolymer rubber containing 50% or more, preferably 55% or more of isoprene units.

Note that the liquid imprene-7tadiene copolymer rubber has a random copolymer, polyisoprene block tI, and polybutadiene block t-B, depending on the bonding mode, 1-n diblock, I-B. - ■ or B -
There are block copolymers such as i-H triblock and multiblock, and any of these are preferably used.

In the present invention, the liquid diene rubber has an average molecular weight of 6,000 to 100,000. Preferably 10,000
Preferably, it is within the range of ~60,000. If the average molecular weight of the liquid diene rubber is too small, the co-vulcanization of the hydrogenated product produced by hydrogenation and butyl rubber will be poor, and when it is blended with butyl rubber and then vulcanized to form a vulcanizate, vulcanization will occur. The decline in the strength and elongation properties of the product increases. on the other hand,
If the average molecular weight is too large, the viscosity of the hydrogenated product produced by hydrogenation will increase, and even if the hydrogenated product is blended, the molding processability of butyl rubber will not be improved, and furthermore, the surface of the vulcanizate will not improve. Smoothing becomes difficult tI & 1. Note that the average molecular weight here refers to the viscosity average molecule m (My)
The viscosity average molecular weight (Jl) is determined by measuring the normal viscosity ([η]) at 30°C in a toluene layer liquid.
= 1.21 XI O' (1) It is obtained by calculating from the formula.

In the present invention, the amount of vinyl bonds in the liquid diene rubber is preferably 30% or less, preferably 20% or less. Vinyl bond amount, i.e. 1.2 bonds and/or
Alternatively, if the amount of 3.4 bonds exceeds 3σ%, the glass transition temperature of the liquid diene rubber becomes too low and the fluidity becomes poor, and furthermore, it can be used as a vulcanizate after hydrogenation to obtain its low-temperature properties. decreases, which is not desirable.

Such liquid diene rubbers include natural rubber and synthetic rubber.
It can be produced by thermally decomposing a solid rubber such as 1,4-polyisoprene rubber or polybutadiene rubber, or by polymerizing a conjugated diene using a known method. In the present invention, since the produced liquid diene rubber contains few impurities, it is preferably produced by the latter method, that is, the present method. Examples of polymerization methods include radical polymerization, anionic polymerization, and Ziegler polymerization. Above all, it is easy to control the molecular weight, and the amount of vinyl bonds can be kept low.
Further, in the case of inbrene-butadiene copolymer rubber, an anionic polymerization method using a lithium-based initiator is most preferable because the form of copolymerization can be easily changed.

The liquid diene rubber may have a functional group such as a carboxyl group, an acid anhydride group, or a hydroxyl group at the molecular end or in the molecular chain.

Such a liquid diene rubber is hydrogenated by a known method to obtain a hydrogenated product. Examples of hydrogenation reactions include metals such as nickel, palladium, platinum, ruthenium, or rhodium supported on carbon or alumina, heterogeneous catalysts such as Raney nickel, Urushihara nickel, or transition metal halides and aluminum, alkalis. Using a homogeneous catalyst such as a Ziegler catalyst in combination with an alkylated product of an earth metal or an alkali metal, it is heated at room temperature to 200°C with hydrogen gas at normal pressure to 300 atm for 1 to 2 minutes.
Examples include a method of contacting for 0 hours, and a method of ring formation with p-toluenesulfonyl hydrazide.

In this way, a hydrogenated product of liquid diene rubber is obtained, and in the present invention, the iodine value of the hydrogenated product is 10 to 10.
250, preferably 10-200, more preferably 1
It is important that the number is within the range of 5 to 150. If the iodine value of the hydrogenated product is too small, the co-vulcanization of the hydrogenated product and butyl rubber will be poor, resulting in a large decrease in the strength and physical properties of the vulcanized product from the resulting composition, and the hydrogenated product will bleed and Migration is likely to occur. On the other hand, if the iodine value is too high, even if it is blended with butyl rubber to form a composition and the composition is vulcanized, the surface will not necessarily be smooth and its aging resistance will deteriorate. In addition, the iodine value is J18 → 070
It is determined by the method specified by.

In the present invention, the hydrogenated compound of the liquid diene thread rubber is blended in an amount of 3 to 40 parts by weight, preferably 5 to 30 parts by weight, per 100 N parts of butyl rubber. If the blending ratio is too large, a vulcanized product with superior strength and elongation properties cannot be obtained even if it is blended with butyl rubber and vulcanized. - If the mounting weight is too small, the molding processability of butyl rubber will not be improved.

The rubber composition of the present invention contains rubber compounding chemicals commonly used in the rubber industry. Rubber compounding chemicals include sulfur, peroxide, vulcanizing agents such as alkylphenol resins, crosslinking agents, processing aids such as ml, stearic acid, vulcanization accelerators, carbon black, silica, clay, etc.
Calcium carbonate, etc., filler, adhesion promoter resin, anti-aging natural rubber (Nl(), imprene rubber (111), butadiene rubber (Bl(), styrene)
Butadiene copolymer rubber (iMflll), chloroprene rubber (aii), butyl rubber (llb), ethylene-propylene copolymer rubber with water-based additives (within a range of 5 or less parts per 100 parts of total) Plasticizers such as process oil and dioctyl phthalate may be mixed within a range that does not deteriorate the aging resistance of the vulcanizate made from the superior rubber composition and does not cause bleeding or migration. Strength and elongation physical properties tl of vulcanizate from rubber composition
-Prepared by kneading the hydrogenated rubber compound and each embroidery rubber compounding agent within a range that does not cause deterioration, using an open roll, Banbury mixer, kneader, etc., and molding using a press, calender, extruder, etc. It is made into a product by vulcanization.

The rubber composition of the present invention can be used for tubes or inner liners of tires such as automobiles or bicycles, tubes for poles, [M coatings, waterproof sheets, sealing materials, lining materials, anti-vibration rubber, pharmaceutical rubber plugs, heat-resistant belts, etc. Preferably used in this field.

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the same extent by these Examples.

Examples 1 to 3 and Comparative Examples 1 to 4 Liquid polyisoprene rubber with a molecular weight of 26,000 and a vinyl bond content of 13% (in Table 1, LIH
) was prepared. Using 4% by weight of palladium-carbon supported catalyst with respect to this liquid polyisoprene rubber,
Hydrogenated products with iodine values (abbreviated as IV in the first gen) of 168.65.25 and 5 were prepared by hydrogenating in an autoclave at 120°C and a hydrogen pressure of 20 ky/al. .

Using each of these hydrogenated substances, butyl rubber, and each of the rubber compounded chemicals, they were mixed using an open roll at the compounding ratios shown in Table 1 to prepare butyl rubber compositions. For comparison, butyl rubber compositions were prepared using non-hydrogenated liquid polyisoprene rubber (iodine value 370) and process oil instead of the hydrogenated material. At that time, the quality of molding processability was also evaluated. Roll processability is evaluated by comprehensively considering the filler kneading time, how well the filler is rolled onto the roll, and workability during cutting, and calender formability is evaluated based on whether the sheet has a smooth mirror surface after calendering. The evaluation was made by observing whether the skin showed rough skin or uneven Ezu skin.

The obtained rubber composition was press-vulcanized at 180°C for 30 minutes.
A plate-shaped vulcanizate of X10X1ad was prepared.

Regarding the obtained vulcanizate, according to JISK6301, it was
The vulcanizate was immersed in benzene at 25° C. for 48 hours, and the amount of benzene extracted from the vulcanizate was determined from the change in weight before and after immersion. The results are shown in Table 1.

As is clear from Table 1, by blending liquid polyisoprene rubber, its hydrogenated product, or oil with butyl rubber, the Mooney viscosity decreases, and with the exception of some calendering properties, the molding processability of these products decreases. This is improved compared to the one that does not contain it at all (Comparative Example 1).

However, in the case of a composition containing a hydrogenated substance or oil with a low iodine value, the strength and elongation properties of the vulcanizate are lower than those of Comparative Example 1, and even when the benzene extract is It's big. Night watches indicate that bleed and migration may occur and that there are problems with solvent resistance. - In a rubber composition blended with a hydrogenated substance having an iodine value of 168 to 25, the strength and elongation properties of the vulcanizate were improved compared to Comparative Example 1, and the benzene extractable content was improved. It's also small. This is because the crosstalk situation has been improved.
I appreciate that it is completely co-vulcanized.

Example 4 and Comparative Examples 5 to 6 Liquid polyisogrene rubber having a molecular weight of 33,000 and a vinyl bond content of 12% was prepared by the same polymerization method as in Example 1 except that the amount of butyllithium was changed. A hydrogenated product of the rubber having a shodine number of 30 was prepared in the same manner as the hydrogenation method of Example 1 except that the rubber was used.

This hydrogenated product, butyl rubber, and various rubber compounding chemicals were mixed in an oven roll at the mixing ratios shown in Table 2 to prepare a butyl rubber composition. For comparison, a butyl rubber composition was prepared using process oil in place of the hydrogenated substance. At that time, the quality of molding processability was evaluated in the same manner as in Example 1.

Using the obtained rubber composition, a 4×10×lcII plate-shaped vulcanizate was prepared under the same vulcanization conditions as in Example.

The obtained rubber composition was subjected to shiveless vulcanization under the same vulcanization conditions as in Example 1 to prepare a plate-shaped vulcanizate of 4×10×1c1M.

The vulcanizate was examined for strength and elongation properties and benzene extractables in the same manner as in Example 1. In addition, by measuring the physical properties of the vulcanized product after heating it at 150° C. for 48 hours, the retention rate of the strength and elongation physical properties before the heat treatment was determined, and the aging resistance was evaluated. These results are shown in Table 2.

Table 2 Butyl rubber (butyl 301) 100
85 100LIR hydrogen additive -1
5-Oil --20 Zinc white 4 4 4 Carbon book (SRF') 60
60 60 stearic acid
l 1 ] Sulfur
0.75 0.75 0.7
50-ru workability k～O○ 0M
3DOCkg/cJ) 77
71 35 Breaking strength (#/J) t
lo 108 103 Elongation at break (%)
570 590 830M300 retention rate (96) 78 74
62 Breaking strength retention rate (96) 53 57
49υ dibenzothiazyl disulfide Tsukusela-DM manufactured by Ni-Ouchi Shinko Kagaku■ Difference in vulcanizate hardness before and after heating Example 5 and Comparative Examples 7 to 8 Using n-butyllithium as a catalyst, isoprene and butadiene were sequentially added. By polymerizing I(-11-I+
A liquid imprene-butadiene copolymer rubber (abbreviated as LIBB in Table 2) of H was prepared. The molecular weight of the rubber is 47,000, and the amount of vinyl bonds (1,2 bonds and 3.
The total of 4 bonds (111k) was 189b, and the heavy filtration ratio of the ■block/B block was 70/30. This liquid copolymer rubber was hydrogenated using nickel under the same conditions as in Example 1 to prepare a hydrogenated product having an iodine value of 42.

Using this hydrogenated product and butyl rubber, a rubber composition was prepared using an open roll according to the formulation shown in Table 3.

At that time, moldability was evaluated using the same method as in Example 1. For comparison, non-hydrogenated liquid copolymer rubber (iodine value 399) was used instead of the hydrogenated material.
A t-compounded rubber composition was prepared.

The rubber composition was press-vulcanized under the same vulcanization conditions as in Example 1, and the physical properties of the obtained vulcanizate in terms of strength and elongation, its benzene extractable content, and aging resistance were examined. The results are shown in Table 3.

Table 3 Butyl Column (Butyl 301) 100
ss 85LIBR-15
- LIBR hydrogen additive -115 zinc white
5 5 5 Car pump hook (FEF) 60
60 60 stearic acid
]11 Sulfur 1.6 1
．． 6 1.6 Vulcanization accelerator TT 1
1 10-ru processability
× ○ 0M30D Ckg〆J)
65 28 7] Breaking strength (〃
) 119 103 103 Elongation at break (%) 670 490. 55
0Maoo retention rate (%) 62 5
4 67 Breaking strength retention rate (%) 66
51 70 Breaking elongation retention rate (%)
1os 121 108 [Effects of the Invention] The rubber composition of the present invention has excellent moldability and has no problems of bleeding or migration after vulcanization.
Provides a vulcanizate with excellent aging resistance and enviable physical properties such as modulus, breaking strength and hardness.

Claims (4)

[Claims] (1) Hydrogenated product with an iodine value of 10 to 250 obtained by hydrogenating butyl rubber (a) and liquid diene rubber (
A rubber composition consisting of b). (2) The rubber composition according to claim 1, wherein the liquid diene rubber is liquid polyisoprene rubber. (3) The rubber composition according to claim 1, wherein the liquid diene rubber is a liquid isoprene-butadiene copolymer rubber. (4) The average molecular weight of the liquid diene rubber is 6,000 to 1
00,000. The rubber composition according to any one of claims 1, 2, or 3.