JPS61101542A - Rubber composition - Google Patents

Abstract

PURPOSE:To obtain a rubber compsn. which gives a vulcanized rubber having improved mechanical properties, by blending an ester derived from a liquid diene polymer contg. hydroxyl groups at its terminals and an alkenyl succinic anhydride with a solid rubber. CONSTITUTION:A rubber compsn. consists of a solid rubber and an ester derived from a liquid diene polymer contg. hydroxyl groups at its terminals and an alkenyl succinic anhydride. The ester is used in a quantity of 1-50pts.wt., pref. 5-45pts.wt. per 100pts.wt. solid rubber. The rubber compsn. can be obtd. by blending the solid rubber with the ester and kneading the mixture. Examples of the solid rubbers are synthetic and natural rubber. Optionally, crosslinking agent, vulcanizing agent, vulcanization accelerator, vulcanizing acid, antioxidant, reinforcing agent, filler, tackifier, plasticizer, etc. may be added to the compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to rubber compositions, and more particularly to rubber compositions that provide vulcanized rubber with improved mechanical properties.

BACKGROUND ART Conventionally, rubber compositions made by blending solid rubber with a liquid diene polymer having a hydroxyl group at the end have been known, and vulcanized rubber obtained from this composition is used for cushioning materials and the like.

However, although this composition has excellent workability such as handling during compounding, there is room for improvement in the mechanical properties, particularly the tensile strength and modulus, of the vulcanized rubber obtained from this composition. Furthermore, it also has the disadvantage of a large amount of dynamic heat generation.

Therefore, as a result of intensive research to develop a rubber composition that eliminates the above-mentioned drawbacks, the present inventor discovered that the desired rubber composition could be obtained by adding a specific substance to solid rubber, and based on this knowledge, As a result, the present invention was completed.

That is, the present invention is a rubber composition comprising a solid rubber and an esterified product of a liquid diene polymer having a terminal hydroxyl group and alkenyl succinic anhydride.

In the present invention, the solid rubber is not particularly limited, and synthetic rubber, natural rubber, etc. are widely used.

Specifically, butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), isoptylene-isoprene rubber (I)
IR) and mixtures thereof.

Next, the esterified product of the liquid diene polymer having a terminal hydroxyl group and alkenyl succinic anhydride of the present invention is obtained by subjecting a liquid diene polymer having a terminal hydroxyl group and alkenyl succinic anhydride to a esterification reaction. That's what you get. Here, the liquid diene polymer having a hydroxyl group at the terminal has a number average molecular weight of 300 to 20,000, preferably about 500 to 6,000, and a hydroxyl group equivalent of 0.1 to 10 meq.
/g, preferably 0.3 to 3 meq/g. Specifically, butadiene homopolymer, isoprene homopolymer, butadiene-styrene copolymer, butadiene-isoprene copolymer.

Examples include butadiene-acrylonitrile copolymer, butadiene-2-ethylhexyl acrylate copolymer, butadiene-n-octadecyl acrylate copolymer, and the like.

Furthermore, alkenyl succinic anhydride is a succinic anhydride having an alkenyl group, and the alkenyl group specifically includes olefins such as tetradecenyl group, hexadecenyl group, and octadecenyl group, and olefin oligomers such as propylene oligomer and isobutylene oligomer. Can be mentioned.

The esterification reaction may be carried out by a commonly used method and is not particularly limited. That is, a liquid diene polymer having a hydroxyl group at the -1 terminal and alkenyl succinic anhydride are blended at a reaction temperature of 10 to 200°C, preferably 70 to 180°C, and a reaction pressure of 1 to 10 atm, preferably 1 to 5 atll. The reaction may be carried out for 0.5 to 24 hours, preferably 1 to 12 hours. The blending ratio of the liquid diene polymer having a hydroxyl group at the end and the alkenyl succinic anhydride may be determined by considering the hydroxyl equivalent of the liquid diene polymer, etc. The above alkenyl succinic anhydrides should be used.

Further, although this reaction proceeds even in the absence of a solvent, it is preferable to use a solvent. Examples of solvents used in this case include benzene, toluene, and xylene. Furthermore, sulfuric acid, para-toluenesulfonic acid, etc. can also be used as an esterification catalyst.

The esterified product thus obtained has a number average molecular weight of 4
00-25000, preferably 600-6000, viscosity 0.1-3000 poise/25°C, preferably 1-10
It has an acid value of about 1 to 1000 mgKOH/g, preferably 10 to 300 mgKOH/H.

The rubber composition of the present invention can be obtained by blending and kneading the solid rubber and the esterified product obtained as described above.

The present invention basically consists of these two components, the solid rubber and the esterified product, but various additives can be added as necessary. The additives used in this case are sulfur,
Crosslinking or vulcanizing agents such as organic sulfur compounds, metal oxides, and polyamines; Vulcanization accelerators such as aldehyde-amines, dithiocarbamates, guanidines, and sulfides; Vulcanization accelerators such as metal oxides and fatty acids ; Anti-aging agents such as amines, amine-aldehyde reactants, amine-ketone reactants, phenols; carbon blank,
Reinforcing agents such as white carbon; Fillers such as calcium carbonate, basic magnesium carbonate, diatomaceous earth, and clay; Tackifiers such as hydrogenated rosin, coumaron-indene resin, and polybutene; Dimethyl phthalate (DMP)
Plasticizers such as , diethyl phthalate (DEP), and dioctyl phthalate (DOP); paraffinic, naphthenic, and aromatic process oils.

The composition of the present invention can be obtained by blending the above components. The blending ratio of the solid rubber and the esterified product is not particularly limited, but it is usually 1 to 50 parts by weight, preferably 5 to 45 parts by weight, of the esterified product per 100 parts by weight of the solid rubber.

If the amount of the esterified product is less than 1 part by weight, the workability of rubber kneading will be poor, and if it exceeds 50 parts by weight, the physical properties of the composition will deteriorate and a bleed phenomenon will occur, which is undesirable.

The components may be blended using an internal mixer roll, two rubber kneading rolls, etc. at 10 to 120°C, preferably 20 to 80°C, for 5 to 200 minutes, preferably 10 to 60 minutes.

The vulcanized rubber obtained by vulcanizing the rubber composition thus obtained has mechanical properties, particularly tensile strength of 30
It has excellent 0% modulus and low dynamic calorific value.

Therefore, the rubber composition of the present invention can be very suitably used for cushioning materials, tires, etc.

Next, the present invention will be explained in detail with reference to examples.

Production example (Production of esterified product of liquid diene polymer having a hydroxyl group at the end and alkenyl succinic anhydride) Liquid polybutadiene having a hydroxyl group (manufactured by Idemitsu Petrochemical Co., Ltd., number average molecular weight 2800, hydroxyl equivalent 0.82 meq)
/g) and 52.8 g of a maleic anhydride adduct of isobutyne tetramer were placed in a No. 11 flask equipped with a reflux tube together with 200 ml of benzene, and the reaction was carried out under reflux for 4 hours. Thereafter, benzene was distilled off to obtain a pale yellow liquid esterified product.

This product has a viscosity of 50 voids/25°C and a number average molecular weight of 28.
30. The acid value was 67 KOH/g.

Examples 1 and 2 and Comparative Examples 1 to 3 Predetermined amounts of each component shown in Table 1 were blended and kneaded at 45° C. for 30 minutes using an internal mixer roll to produce a rubber composition.

The obtained rubber composition was press-vulcanized at 150° C. for 30 minutes to obtain a vulcanized rubber. The tensile strength of this thing.

The measurement results of elongation, 300% modulus and calorific value are shown in Table 1.

Table 1 *1: Manufactured by Idemitsu Petrochemical ■, number average molecular weight 2800,
Hydroxyl equivalent: 0.79 meq/g, product name: rPoly
bd R-45HTJ*2...Oil Furnace Black*3...Measured with Koka type flow tester*4...J
Conforms to ISK-6301 *5: Conforms to ASTM D-623 Using Gutdrich flexometer Measurement conditions: 251b, stroke 4.4, temperature 10
0℃, rotation speed

Claims (2)

[Claims] (1) A rubber composition comprising a solid rubber and an esterified product of a liquid diene polymer having a terminal hydroxyl group and alkenyl succinic anhydride. (2) 1 to 50 parts by weight of an esterified product of a liquid diene polymer having a terminal hydroxyl group and alkenyl succinic anhydride is blended with 100 parts by weight of the solid rubber. Rubber composition.