JPH037214B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a rubber composition, and particularly to a rubber composition having improved cut resistance and chipping resistance by incorporating a specific hydroxyl group-containing cyclopentadiene resin. (Prior art) Large tires for heavy-duty trucks and buses that often run on unpaved roads, especially rough roads with exposed rocks, and off-the-road tires used at quarry sites, etc. There are many opportunities for cuts to occur in the steel cord reinforcement and sidewall areas, and these cuts can grow and cause tire damage, or rainwater that has entered through the cuts can corrode the steel cord reinforcing material and cause tire damage. Therefore, there is a need for a rubber composition that has excellent cut resistance and chipping resistance, particularly for the tread portion of the tire. Generally, as a means of improving the cut resistance of a rubber composition, a method of highly filling carbon black is used, but while this improves the cut resistance, it is also necessary for driving on rough roads. However, there were problems in that chipping resistance and heat generation properties were extremely poor, and kneading and extrusion workability were also extremely poor. In contrast, one of the applicant's companies
-38615 publication, softening point 50~200℃, bromine number 40~
150 dicyclopentadiene resin to styrene
By blending with butadiene copolymer rubber,
It is described that the cut resistance of the rubber composition can be improved, but although the cut resistance has improved considerably, there is still a drawback that the chipping resistance is poor. (Problems to be Solved by the Invention) The present invention provides an extremely useful rubber composition that exhibits excellent cut resistance and chipping resistance when used in the treads of large tires running on rough roads and off-the-road tires. Solve the problem of providing things. (Means for Solving the Problems) As a result of intensive studies to solve the above problems, the present inventors discovered that a compound having a cyclopentadiene ring or its Diels-Ander adduct and a polymerizable double bond in the molecule. It was confirmed that the above-mentioned problems could be solved by blending into rubber a hydroxyl group-containing cyclopentadiene resin copolymerized with a compound having both a bond and a hydroxyl group, and the present invention was accomplished. That is, the present invention provides that, for 100 parts by weight of at least one rubber selected from the group consisting of natural rubber and synthetic rubber, the general formula (In the formula, R represents an alkyl group having 1 to 3 carbon atoms, and m is an integer of 0 to 6.) A group consisting of compounds having a cyclopentadiene ring and their Diels-Ander adducts. 100 parts by weight of component A, which is at least one compound selected from the following, and components B2 to 120, which are compounds having both a polymerizable double bond and a hydroxyl group in the molecule.
This is a rubber composition characterized by blending 1 to 30 parts by weight of a hydroxyl group-containing cyclopentadiene resin obtained by heat copolymerizing with parts by weight. In this invention, the synthetic rubber includes synthetic polyisoprene rubber, polybutadiene rubber, styrene butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene propylene terpolymer, acrylonitrile butadiene rubber, etc., and these may be used alone or as a blend. Natural rubber may be used alone or in a blend with at least one of the synthetic rubbers mentioned above. In this invention, component A includes compounds of general formula 1, such as cyclopentadiene and methylcyclopentadiene, and Diels-Ander adducts of compounds of general formula 1, such as dicyclopentadiene, cyclopentadiene-methylcyclo Pentadiene codimers, tricyclopentadiene, etc. are mentioned, and these and mixtures thereof are preferably used industrially, and among these, cyclopentadiene, dicyclopentadiene, or a mixture of both is particularly preferred. Although it is not necessarily necessary that cyclopentadiene, dicyclopentadiene or its alkyl-substituted derivatives have high purity, cyclopentadiene, dicyclopentadiene or its alkyl-substituted derivatives are
Preferably, it is present in an amount of 80% by weight or more. In addition, by thermally dimerizing cyclopentadiene and methylcyclopentadiene contained in the _C5 fraction of high-temperature pyrolysis byproduct oil such as naphtha, dicyclopentadiene, dimethylcyclopentadiene, cyclopentadiene-methylcyclopentadiene, etc. codimer, cyclopentadiene-isoprene codimer,
It is also possible to use a concentrated fraction obtained by forming a mixture of cyclopentadiene-piperylene codimer, etc., and then removing most of the _C5 components such as _C5 olefins and _C5 paraffins by distillation. . Component B, that is, a compound having both a polymerizable double bond and a hydroxyl group in the molecule, includes allyl alcohol, methallyl alcohol, crotyl alcohol, cinnamyl alcohol, methyl vinyl carbinol, allyl carbinol, and methyl propenyl carbinol. unsaturated alcohols such as 2-butene-1,4-diol, 3-hexene-2,5-
Component A such as unsaturated dihydric alcohols such as diols, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc.
and a hydroxyl group-containing unsaturated compound having 3 to 22 carbon atoms that can be thermally copolymerized with the hydroxyl group, and mixtures of two or more thereof. Among these, allyl alcohol, 2-butene-1,4-diol, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate are preferred because they can be easily obtained industrially. The hydroxyl group-containing cyclopentadiene resin used in this invention is based on 100 parts by weight of the above component A, and 2 parts by weight of component B.
~120 parts by weight, preferably 5 to 100 parts by weight to 150 to 120 parts by weight
10 minutes to 20 hours at 300℃, preferably 200-280℃,
Preferably, it can be produced by carrying out a heating reaction in the absence of a catalyst for 1 to 10 hours. In the hydroxyl group-containing cyclopentadiene resin used in this invention, the ratio of component B to component A in the copolymerization reaction carried out for its production is extremely important, and the amount of component B is 2 parts by weight per 100 parts by weight of component A. If it is less than 120 parts by weight, the cut resistance and chipping resistance of the final rubber composition obtained will be insufficient, and if it exceeds 120 parts by weight, the resin yield will be extremely low and the softening point of the resin will be lowered. Not only does this decrease, but the cut resistance also decreases, and blocking of the resin occurs, resulting in poor refining workability. Further, in producing the above-mentioned hydroxyl group-containing cyclopentadiene resin, it is also possible to use an unsaturated component in a petroleum fraction, particularly an unsaturated aromatic component, in an amount equal to or less than the amount of component A. For example, styrene
α-methylstyrene, vinyltoluene, indene, methylindene, and mixtures thereof can be used, and from an industrial perspective, the so-called _C9 fraction, which is produced as a by-product during the decomposition of naphtha and the like, is preferred. The performance of the rubber composition can be improved to some extent by the combined use of such unsaturated components in petroleum fractions, and the cut resistance can be further improved by the combined use of, for example, styrene. In this case, there is no change in the amount range of component B used relative to component A. The hydroxyl group-containing cyclopentadiene resin used in this invention is manufactured using the ring and ball method (based on JIS K2531-60).
Softening point measured by 50~180℃, especially 70~160℃
Preferably, it is in the range of °C. If the softening point is lower than 50°C, the modulus of the rubber composition under low elongation will not only decrease, but also the cut resistance will deteriorate.
Resin tends to cause blocking and refining workability deteriorates. On the other hand, if the temperature is higher than 180℃,
Uniform dispersion in rubber becomes difficult. The amount of the hydroxyl group-containing cyclopentadiene resin used in this invention is 1 to 30 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of rubber. If the amount is less than 1 part by weight, the addition has no effect and the cut resistance and chipping resistance are not improved. On the other hand, if the amount is more than 30 parts by weight, not only the effect of increasing the amount can no longer be expected, but also physical properties such as abrasion resistance are significantly deteriorated. In this invention, in addition to the hydroxyl group-containing cyclopentadiene resin, compounding agents commonly used in the rubber industry, such as reinforcing fillers, vulcanizing agents, vulcanization accelerators, vulcanization accelerators, softeners, Anti-aging agents and the like can be added as appropriate. (Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, Comparative Examples, and Reference Examples. Reference example 1 Dicyclopentadiene (DCPD) with a purity of 97%
574 g of allyl alcohol, 126 g of allyl alcohol (22.6 parts by weight per 100 parts of DCPD), and 300 g of mixed xylene were placed in the autoclave No. 2, and heated at 260° C. for 3 hours under stirring in a nitrogen atmosphere. After heating, it was cooled in an autoclave, and the contents were distilled to remove unreacted monomers, low polymers, and xylene, and 590 g of Resin No. 1 was obtained as a residue. Resin No.
The softening point of No. 1 is 105.0℃, and the hydroxyl value is 132mgKOH/
It was hot at g. Reference example 2 DCPD 417g with purity 97%, allyl alcohol 69g
g (17.0 parts by weight per 100 parts by weight of DCPD), 302 g of aromatic fraction with a boiling point range of 140 to 280°C produced by thermal decomposition of naphtha, and 212 g of mixed xylene were heated at 260°C for 3.5 hours while stirring in an autoclave. The reaction was carried out in the same manner as in Reference Example 1 to obtain 534 g of resin No.
I got 2. Resin No. 2 had a softening point of 97.5°C and a hydroxyl value of 97 mgKOH/g. Reference example 3 610 g of DCPD with a purity of 97%, 2-butene-1,4
-Diol (mixture of cis and trans forms) 90g
(15.2 parts by weight per 100 parts by weight of DCPD) and 300 g of mixed xylene were stirred in an autoclave.
The reaction was carried out at 270° C. for 4.0 hours and treated in the same manner as in Reference Example 1 to obtain 618 g of Resin No. 3. Resin No. 3 had a softening point of 136.5°C and a hydroxyl value of 146.6 mgKOH/g. Reference example 4 459 g of DCPD with a purity of 97%, 241 g of 2-hydroxyethyl acrylate (per 100 parts by weight of DCPD)
54.1 parts by weight) and 300 g of mixed xylene were reacted at 260°C for 4.0 hours while stirring in an autoclave, and treated in the same manner as in Reference Example 1 to obtain 571 g of Resin No. 4.
I got it. The softening point of resin No. 4 is 93.0℃, and the hydroxyl value is
It was 131mgKOH/g. Reference example 5 C ₅ is a by-product when producing ethylene, propylene, etc. by steam cracking naphtha.
When the cracked fraction (boiling point 28-60℃) is heated at 120℃ for 4 hours and the _C5 fraction is removed by distillation, 85%
A residue is obtained containing DCPD and 15% codimer of cyclopentadiene and isoprene or piperylene. 675g of this residue containing 85% DCPD,
126 g of allyl alcohol (22.0 parts by weight per 100 parts by weight of DCPD) and 199 g of mixed xylene were stirred in an autoclave and reacted at 270°C for 8 hours, and treated in the same manner as in Reference Example 1 to produce 688 g of resin No. 5.
I got it. Resin No. 5 had a softening point of 154.0°C and a hydroxyl value of 149 mgKOH/g. Reference example 6 403g of DCPD with a purity of 97%, 226g of aromatic fraction with a boiling point range of 140 to 280℃ produced by thermal decomposition of naphtha
and 371 g of mixed xylene were heated and reacted at 260° C. for 3 hours while stirring in an autoclave, and treated in the same manner as in Reference Example 1 to obtain 490 g of comparative resin a.
The softening point was 131°C. Reference example 7 500g of DCPD with a purity of 97% and 500g of mixed xylene
was reacted by heating at 250℃ for 4 hours while stirring in an autoclave, and treated in the same manner as in Reference Example 1 to obtain 342.
Comparative resin b of g was obtained. The softening point was 108°C. Examples 1 to 5, Comparative Examples 1 to 2 Each of the resins synthesized in Reference Examples 1 to 7 was added to 100 parts by weight of styrene-butadiene rubber (SBR1500).
Using 12 parts by weight, the other ingredients shown in Table 1 were kneaded in a Banbury mixer, then vulcanized, and the cut resistance and tread appearance when these rubber compositions were used for tire treads were determined as shown below. We considered gender. The results are shown in Table 1. The various tests are as follows. (a) Cut resistance A steel blade is struck from a certain height using a pendulum type impact cut tester to create a scratch, the depth of the cut is measured, and the value of Comparative Example 1 is set as 100 and expressed as an index. did. The larger the value, the better the cut resistance. (b) Tradition appearance test A 1000R20 truck/bus tire was made from the rubber composition shown in Table 1 by dividing the tread into four parts and driving it for 5000km on a rough road with many protruding rocks such as a quarry while frequently braking suddenly. After running, the number of large cuts (scratches with a depth of 5 mm or ^more ), small cuts (scratches with a depth of 1 mm or more and less than 5 mm), and chips (small pieces of rubber with an area of 25 mm or more) were removed per 100 cm ² of the tored surface. Phenomenon) number was evaluated and expressed as an index with Comparative Example 1 set as 100. The larger the value, the better.

[Table] *1 Anti-aging agent manufactured by Mitsubishi Monsanto Chemical Co., Ltd. As is clear from Table 1, the rubber composition of the present invention has significantly improved cut resistance and chipping resistance. I understand. Examples 6 to 10, Comparative Examples 3 to 4 Rubber compositions were prepared with the formulations shown in Table 2, and evaluated in the same manner as in Example 1. The results are shown in Table 2. The results are expressed as an index with Comparative Example 3 set as 100, and similarly, the larger the value, the better the results.

【table】

[Table] *1 Anti-aging agent manufactured by Mitsubishi Monsanto Chemical Co., Ltd. As is clear from Table 2, the rubber composition of the present invention has significantly improved cut resistance and chipping resistance even in natural rubber systems. It can be seen that it has been significantly improved. (Effects of the Invention) The rubber composition of the present invention, which is a mixture of natural rubber and/or synthetic rubber with a specific hydroxyl group-containing cyclopentadiene resin, has excellent cut resistance and chipping resistance, and is therefore suitable for use in tires, especially on rough roads. It is useful for treading large tires that are frequently driven, but it can also be used in tire sidewalls and other components, or in other rubber products such as conveyor belts and hoses.

Claims (1)

[Scope of Claims] 1. For 100 parts by weight of at least one rubber selected from the group consisting of natural rubber and synthetic rubber, the general formula (In the formula, R represents an alkyl group having 1 to 3 carbon atoms, and m is an integer of 0 to 6.) A group consisting of compounds having a cyclopentadiene ring and their Diels-Alder adducts. 100 parts by weight of component A, which is at least one compound selected from the following, and components B2 to 120, which are compounds having both a polymerizable double bond and a hydroxyl group in the molecule.
1. A rubber composition comprising 1 to 30 parts by weight of a hydroxyl group-containing cyclopentadiene resin obtained by heat copolymerizing with parts by weight. 2. The rubber composition according to claim 1, wherein component A is cyclopentadiene, methylcyclopentadiene, dicyclopetadiene, cyclopentadiene-methylcyclopentadiene copolymer, or tricyclopentadiene. 3. The rubber composition according to claim 1, wherein component B is an unsaturated alcohol having 3 to 22 carbon atoms, an unsaturated dihydric alcohol, a hydroxyalkyl acrylate, or a hydroxyalkyl methacrylate. 4 Component B is allyl alcohol, 2-butene-
The rubber composition according to claim 1, which is 1,4-diol, 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.