JPS62184039A - Rubber composition - Google Patents

Abstract

PURPOSE:To improve cutting and chipping resistance in application to the treads of large tires or off-road tires for running on a rough road, by adding a specified hydrocarbon resin to a rubber. CONSTITUTION:1-30pts.wt. hydrocarbon resin is added to 100pts.wt. at least one rubber selected from the group consisting of natural and synthetic rubbers. Said hydrocarbon resin is one obtained by copolymerizing 100pts.wt. component A comprising at least one compound selected from a cyclopentadiene ring- containing compound of formula I (wherein R is a 1-3C alkyl and m is an integer of 0-6) and its Diels-Alder adduct with 5-150pts.wt. component B comprising a 5-alkylidenenorbornene-2 of formula II (wherein R<1>, R<2> and R<3> are each H or a 1-3C alkyl group and n is 0 or 1) or its derivative.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a rubber composition, and particularly to a rubber composition with improved cut resistance and chipping resistance by blending a specific hydrocarbon 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 rock crushing sites, etc. There are many opportunities for cuts to occur in the cant and sidewall areas (this cut can grow and cause tire damage, or rainwater that has entered through the cant area can corrode the steel cord reinforcement and cause tire damage). Therefore, there is a need for a rubber composition with excellent cut resistance and chipping resistance, especially for the tread portion of the tire.

Generally, a method of highly filling carbon black is used as a means to improve the cut resistance of a rubber composition, 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 wire crosstalk and extrusion workability were also extremely poor.

In contrast, one of the applicant's companies
615, a softening point of 50 to 200°C, a bromine number of 40 to
It is described that the cut resistance of a rubber composition can be improved by blending a dicyclopentadiene resin of No. 150 into a styrene-butadiene copolymer rubber. However, it had the disadvantage of poor chipping resistance.

(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 tread 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-mentioned problems, the present inventors have found that a petroleum-based hydrocarbon resin copolymerized with 5-alkylidenenorbornene-2 is blended into rubber. In other words, it was confirmed that the above problems could be solved, and the present invention was achieved.

That is, the present invention provides a method in which a small amount of rubber selected from the group consisting of natural rubber and synthetic rubber (both rubbers) of the general formula (wherein R is an alkyl group having 1 to 3 carbon atoms) shows,
m is an integer from 0 to 6. 100 parts by weight of component A, which is at least one compound selected from the group consisting of compounds having a cyclopentadiene ring represented by R3 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is 0 or 1. This is a rubber composition containing 1 to 30 parts by weight of a hydrocarbon resin obtained by copolymerization.

In this invention, synthetic rubber refers to synthetic polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber,
These include butyl rubber, halogenated butyl rubber, ethylene propylene terpolymer, acrylonitrile butadiene rubber, 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 Diels-Alder compounds of general formula I, such as cyclopentadiene, methylcyclopentadiene, etc.
Examples of adducts include dicyclopentadiene, cyclopencdiene-methylcyclopentadiene codimer,
Examples include tricyclopentadiene, and these and mixtures thereof are preferably used industrially, and among these, cyclopentadiene, dicyclopentadiene, or a mixture of both is particularly preferred.

It is not necessarily necessary that cyclopentadiene, dicyclopentadiene, or an alkyl-substituted derivative thereof has high purity, or it is preferable that cyclopentadiene, dicyclopentadiene, or an alkyl-substituted derivative thereof is present in an amount of 80% by weight or more. In addition, C1 of high-temperature pyrolysis by-product oil such as naphtha
By thermally dimerizing cyclopentadiene and methylcyclopentadiene contained in the fraction, dicyclopentadiene, dimethylschiff self-pentadiene, cyclopentadiene-methylcyclopentadiene co-dimer, and cyclopentadiene-isoprene co-dimer are produced. After forming a mixture of dimer, cyclopentadiene-piperylene co-dimer, etc., the concentrated fraction obtained by removing most of C3 components such as C, olefin, and CB paraffin by distillation is used. I can't help it.

As component B, for example, 5-ethylidenenorbornene-22,5-ethylidenemethylnorbornene-2,5-
Examples include ethylidenedimethylnorbornene-2,5-propylidenenorbornene-2,5-isopropylidenenorbornene-2, and these may be used in combination of two or more types. 2 is preferred because it can be easily obtained industrially.

In the present invention, a hydrocarbon resin is produced by reacting 85 to 150 parts by weight, preferably 10 to 100 parts by weight, of the above-mentioned component A with respect to 100 parts by weight in the absence of a catalyst or in the presence of a catalyst. When the reaction is carried out without a catalyst, the mixture of component A and component B is mixed at 200-300%
A hydrocarbon resin can be produced by heating at a temperature of 30 minutes to 15 hours, preferably 1 to 7 hours. On the other hand, when a catalyst is used, a Friedel-Crafts type catalyst, such as boron trifluoride or its complexes such as phenol, ether, acetic acid, or aluminum chloride, is used at 0.1 to 100% relative to the total amount of monomers. % by weight, preferably 0.3 to 2% by weight, in which case the reaction temperature is -30 to 100°C, preferably 0 to 50°C.
℃ and a reaction time of 10 minutes to 20 hours, preferably 1 to 15 hours.

In the hydrocarbon 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.
If the amount is less than 5 parts by weight, the cut resistance and chipping resistance of the finally obtained rubber composition will be insufficient, and if it exceeds 150 parts by weight, the yield of the resin will be extremely reduced. However, not only the softening point of the resin decreases, but also the cut resistance decreases, and blocking of the resin occurs, resulting in poor scouring workability.

Further, in producing the above-mentioned hydrocarbon resin, it is also possible to use an unsaturated component in the 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,
Industrially, the so-called C9 fraction, which is produced as a by-product during the decomposition of naphtha and the like, is preferred.

The combined use of such unsaturated components in petroleum fractions can improve the performance of the rubber composition to some extent, and for example, the combined use of styrene and the like can further improve the cut resistance. In this case, there is no change in the amount range of component B used relative to component A.

The hydrocarbon IIA fat used in this invention is prepared by the ring and ball method (
The softening point measured according to JIS 2531-60 is preferably in the range of 50 to 180°C, particularly 70 to 160°C. When the softening point is lower than 50° C., the modulus of the rubber composition under low elongation is reduced, and not only the cut resistance is deteriorated, but also the resin tends to cause blocking and the scouring workability is deteriorated. On the other hand, if the temperature is higher than 180°C, uniform dispersion in the rubber becomes difficult.

The amount of the hydrocarbon resin used in this invention is 1 to 30 parts by weight, preferably 3 to 151 parts by weight, per 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 chimping resistance are not improved. On the other hand, if it is more than 30 parts by weight,
Not only can no longer be expected to increase the weight, but physical properties such as abrasion resistance deteriorate significantly.

In addition to the above-mentioned hydrocarbon resin, the present invention also uses compounding agents commonly used in the rubber industry, such as reinforcing fillers, vulcanizing agents, vulcanization accelerators, vulcanization accelerators, softeners, and anti-aging agents. Agents, etc. can be blended as appropriate.

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

Reference charcoal 1 Dicyclopentadiene (DcPD) 350 with a purity of 97%
g-5-ethylidenenorbornene-2 (t
iNB) 150g (4 parts per 100 parts by weight of DCPD)
3.3 parts by weight) and 500 g of mixed xylene were placed in a No. 21 autoclave and heated at 250° C. for 5 hours with stirring in a nitrogen atmosphere. After heating, the autoclave was cooled and the contents were distilled to remove unreacted monomers, low polymers, and xylene, yielding 398 g of resin volume 1 as a residue.

The softening point was 96°C.

480 g of DCPo of 97% purity, E of 98% purity
N8220g (46.3 parts per 100 parts by weight of DCPD)
Parts by weight) and 300 g of mixed xylene were reacted by heating at 270°C for 6 hours while stirring in an autoclave 1, Reference Example 1
660 g of resin 11h2 was obtained. The softening point was 145°C.

480 g of 97% pure DCPo, 5 of 98% purity
-isopropylidenenorbornene-222h (DCP
46.3 parts by weight per 100 parts by weight) and 300 g of mixed xylene were reacted by heating at 260°C for 5 hours with stirring in an autoclave, and treated in the same manner as in Reference Example 1 to obtain 630
Resin positive 3 of g was obtained. The softening point was 130°C.

Moxibustion Charcoal 97% pure DCPo 343 g, 98% pure E
86 g of NB (25.3 parts by weight per 100 parts by weight of DCPD), 143 g of an aromatic fraction with a boiling point range of 140 to 280°C produced by thermal decomposition of naphtha, and 428 g of mixed xylene.
g was reacted by heating at 270°C for 5 hours while stirring in an autoclave, and treated in the same manner as in Reference Example 1 to obtain 440 g of resin 1.
1kL4 was obtained. The softening point was 130°C.

C6 cracked fraction (boiling point 2
8 to 60℃) at 120℃ for 4 hours to remove C by distillation.
Removal of the 5 fractions yields a residue containing 85% DCPD and 15% cyclopentadiene and isoprene or piperylene codimer. 470 g of residue containing 85% of this DCPD, 98% pure ENBloh
(24.5 parts by weight per 100 parts by weight of DCPD) and 430 g of mixed xylene were stirred in an autoclave.
The reaction mixture was heated at 260° C. for 3 hours and treated in the same manner as in Reference Example 1 to obtain 430 g of resin 11h5. Softening point is 112
It was ℃.

1111 403 g of DCPo with a purity of 97%, aromatic fraction 2 with a boiling point range of 140 to 280 °C produced by thermal decomposition of naphtha
26 g and 371 g of mixed xylene were heated and reacted in an autoclave at 260° C. for 3 hours while stirring, and treated in the same manner as in Reference Example 1 to obtain 490 g of comparative resin a. Softening point is 1
The temperature was 31°C.

Exchange: 500g of DCPo with 97% purity and 50g of mixed xylene
0 g was heated and reacted in an autoclave at 250° C. for 4 hours with stirring, and treated in the same manner as in Reference Example 1 to obtain 342 g of comparative tree ptJb. The softening point was 108°C.

Styrene-butadiene rubber (SBR1500) 100
12 parts by weight of each of the resins synthesized in Reference Examples 1 to 7
Parts by weight were used, and the other ingredients listed in Table 1 were kneaded in a Banbury mixer, then vulcanized, and the cut resistance and tread appearance when these rubber compositions were used in tire trends as shown below. We considered gender. The results are shown in Table 1.

Various test methods are as follows.

(B) Cut resistance A steel blade is struck from a certain height using a pendulum type impact cutting 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) Tread appearance test The tread was divided into four parts and 10
After making 00R20 trunk and bus tires and driving 5,000km on rough roads with many protruding rocks such as at a quarry, while frequently braking suddenly, the trend surface was 100cm!
Number of large cuts (scratches with a depth of 5III11 or more), small cuts (scratches with a depth of 1++++++ or more and less than 5Il111)
The number and the number of chippings (a phenomenon in which small pieces of rubber with an area of 25 mm+" or more are scraped off) were evaluated and expressed as an index, with Comparative Example 1 set as 100. The larger the value, the better it is.

As is clear from Table 1, the rubber compositions of the present invention have equivalent to significantly improved cut resistance, and significantly improved chipping resistance.

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.

Note that the results are expressed as an index with Comparative Example 3 set as 100, and similarly, the larger the value, the better.

As is clear from Table 2, even in natural rubber systems, the rubber compositions of the present invention have equivalent or significantly improved cut resistance, and significantly improved chipping resistance.

(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 hydrocarbon resin containing an alkylidene norbornene unit, has extremely excellent cut resistance and chipping resistance, and is therefore suitable for use in tires. It is particularly useful in the treads of large tires that frequently travel on rough roads, but it can also be used in tire sidewalls and other components, as well as other rubber products such as conveyor belts and hoses.

Claims (1)

[Claims] 1. For 100 parts by weight of at least one rubber selected from the group consisting of natural rubber and synthetic rubber, a general formula ▲a mathematical formula, a chemical formula, a table, etc.▼ (in the formula, R represents an alkyl group having 1 to 3 carbon atoms,
m is an integer from 0 to 6. 100 parts by weight of component A, which is at least one compound selected from the group consisting of compounds having a cyclopentadiene ring represented by 5-alkylidene norbornene represented by A rubber composition comprising 1 to 30 parts by weight of a hydrocarbon resin obtained by copolymerizing Component B-2 or a derivative thereof, 5 to 150 parts by weight. 2. Component A is cyclopentadiene, methylcyclopentadiene, dicyclopentadiene, cyclopentadiene-
The rubber composition according to claim 1, which is a methylcyclopentadiene copolymer or tricyclopentadiene. 3. Component B is 5-ethylidenenorbornene-2, 5-ethylidenemethylnorbornene-2, 5-ethylidenedimethylnorbornene-2, 5-propylidenenorbornene-2, 5-isopropylidenenorbornene-2 Claim No. Rubber composition according to item 1.