JPS63335A - Rubber composition - Google Patents

Abstract

PURPOSE:To provide a rubber compsn. having excellent resistance to cutting and chipping and suitable for use as a material for the tread of a large-size tire, by blending natural and/or synthetic rubber with a specified resin. CONSTITUTION:100pts.(by weight; the same applies hereinbelow) compd. (a) selected from among compds. having a cyclopentadiene ring, represented by the formula (wherein R is a 1-3C alkyl; and m is a number of 0-6) and Diels- Alder adduts thereof is reacted with 2-120pts. compd. (b) having a polymerizable double bond and hydroxy group(s) selected from the group consisting of 3-22C unsaturated alcohols, unsaturated dihydric alcohols and hydroxy (meth)acrylates at 150-300 deg.C for 10min-20hr to obtain a cyclopentadiene resin having hydroxyl groups. The resin is reacted with a polyisocyante compd. (c) in an equivalent ratio of the isocyanate group to the hydroxyl group in the resin of 0.05-1.5 at 20-280 deg.C for 10min-20hr to obtain a resin. 100pts. natural and/or synthetic rubber (A) are/is blended with 1-30pts. component B.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention improves cut resistance and chipping resistance by blending a rubber composition, particularly a specific hydroxyl group-containing cyclopentadiene resin modified with a polyisocyanate compound. The present invention relates to a rubber composition.

(Prior art) Large tires for heavy-duty trucks and buses that often run on unpaved roads, especially rough roads with exposed rocks, or 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 cut area can corrode the steel cord reinforcing material 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, as a means to improve 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 was a problem that the chipping resistance and heat generation properties were extremely poor, and the kneading and extrusion workability were also extremely poor.

In contrast, one of the applicant's companies
No. 615 describes a softening point of 50 to 200°C and an odor cumulative value of 40 to 200°C.
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 problems, the present inventors found that a compound having a cyclopentadiene ring or its Diels-Alder adduct has polymerizable properties in its molecule. Hydroxyl group-containing cyclopentadiene is copolymerized with a compound having both a double bond and a hydroxyl group.
It was confirmed that the above problems could be solved, and the present invention was achieved.

That is, this invention is based on the general formula (wherein 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 and their Diels-Alder adducts, and a polymerizable double bond in the molecule. Hydroxyl group-containing cyclopentadiene (sealing resin (R1
), and further add component C, which is a polyisocyanate compound, in such a proportion that the equivalent ratio of the amount of incyanate groups in component C to the amount of hydroxyl groups in the resin (R1) is within the range of 0.05 to 1.5. The resin (R2) obtained by the reaction is added in an amount of 1 to 30% per 100 weight ff1fl of at least one rubber selected from the group consisting of natural rubber and synthetic rubber.
This is a rubber composition containing parts by weight.

In this invention, synthetic rubbers include synthetic polyisoprene rubber, polybutadiene rubber, styrene butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene propylene co-polymer, acrylonitrile butadiene rubber, etc., and these may be used alone. It can also be 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 I, such as cyclopentadiene, methylcyclopentadiene, Diels-Alder compounds of general formula
Examples of adducts include dicyclopentadiene, cyclopentadiene-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.

Although it is not necessary that cyclopentadiene, dicyclopentadiene, or an alkyl-substituted derivative thereof has high purity, 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, C5 of high-temperature pyrolysis by-product oil such as naphtha
By thermally dimerizing cyclopentadiene and methylcyclopentadiene contained in the fraction, dicyclopentadiene, dimethylcyclopentadiene, cyclopentadiene-methylcyclopentadiene codimer, and cyclopencdiene-isoprene are produced. After forming a mixture of codimer, cyclopentadiene-piperylene codimer, etc., the concentrated fraction obtained by removing most of the C5 components such as 05 olefin, C, and paraffin by distillation is used. I don't mind.

Component B, that is, a compound having both a polymerizable double bond and a hydroxyl group in the molecule, includes allyl alcohol, methallylalconopecrotylalconobecin, namylalconopemethylvinylruby, /-ru, and allylcarbyl. unsaturated alcohols such as alcohol, methylpropenyl carbinol, 2-butene-1,4-diol, 3-hexene-2
, unsaturated dihydric alcohols such as 5-diol, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate, 2
- 3 to 2 carbon atoms that can be thermally copolymerized with component A such as hydroxyalkyl methacrylates such as hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate
Two hydroxyl group-containing unsaturated compounds and mixtures of two or more thereof are included.

Hydroxyl group-containing cyclopentadiene resin used in this invention (
R1) is the component 82 to 00 parts by weight of the above component Al.
120 parts by weight, preferably 5 to 100 parts by weight to 150 to 120 parts by weight
300℃, preferably 200-280℃ for 10 minutes to 2
It can be produced by carrying out a heating reaction without a catalyst for 0 hours, preferably 1 hour to 10 hours.

In the sealing resin (R2) 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 120 parts by weight, the cut resistance and chipping resistance of the finally obtained rubber composition will be insufficient, and if it exceeds 120 parts by weight, the yield of the hydroxyl group-containing cyclopentadiene resin (R1) will be reduced. decreased significantly,
Not only the softening point of the resin (R2) is lowered, but also the cut resistance is lowered, and the refining workability is deteriorated due to blocking of the sealant (R2).

In addition, the above hydroxyl group-containing cyclopentadiene resin (R1
), it is also possible to use unsaturated components in the petroleum fraction, especially unsaturated aromatic components, 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 standpoint, 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 polyisocyanate compound of component C is an aliphatic polyisocyanate, an alicyclic polyisocyanate, a heterocyclic polyisocyanate, or an aromatic polyisocyanate, such as butylene-1,4-diisocyanate, ethylene diisocyanate, trimethylene diisocyanate, Tetramethylene diisocyanate, hexamethylene diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate), 2.4-tolylene diisocyanate, 2.6-)lylene diisocyanate, 1,4-phenylene diisocyanate, 1.4-naphthalene diisocyanate, 1,5
-Naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, diphenyl-3,3'-dimethyl-4°4'-diisocyanate, xylene diisocyanate, ■-methoxyphenylene-2,4-diisocyanate, benzene-1,2,4- ) diisocyanate, tolidine diisocyanate, etc., and these two
Mixtures of more than one type can also be used.

Hydroxyl group-containing cyclopentadiene (fat (R1) and component C
The reaction with the polyisocyanate compound is from 20 to 280°C.
, preferably at 30 to 260°C for 10 minutes to 20 hours, preferably 30 minutes to 15 hours. The amount of the positive isocyanate compound used is such that the amount of incyanate groups thereof is 0.05 to 1.5, preferably 0.1 to 1.5 in equivalent ratio to the amount of hydroxyl groups in the hydroxyl group-containing cyclopentadiene sealing resin (R1). This is a range of 1.0.

The amount of polyisocyanate compound is the corresponding amount ratio value of 0.05
If it corresponds to less than δ, the effect of increasing the molecular weight of the resin (R1) will hardly be tolerated, and the cut resistance of the finally obtained rubber composition will be insufficient.

Moreover, when the equivalent ratio exceeds 1.5, the change in the resin over time due to the influence of residual isocyanate groups becomes significant.

The It fat (R2) used in this invention is obtained by the ring and ball method (JI
Softening point measured according to SK2531-60) is 5.
The temperature range is preferably from 0 to 180°C, particularly from 70 to 160°C. When the softening point is lower than 50° C., the modulus of the rubber composition under low elongation is decreased, and not only the proof stress and stiffness are deteriorated, but also the resin tends to cause blocking and the refining 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 resin (R2) 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 cutting properties 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 resin (R2), 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% 57
4g.

126 g of allyl alcohol (22.6 parts by weight per 100 parts by weight of DCPo) and 300 g of mixed xylene were
The mixture was charged into a β autoclave and heated at 260° C. for 3 hours under stirring in a nitrogen cloud atmosphere. After heating, the autoclave was cooled, the contents were distilled to remove unreacted monomers, low polymers, and xylene, and 604 g of t was left as a residue.
A fit fat (A) was obtained. The softening point of resin (a) is 93.0
℃, and the hydroxyl value was 139 mg KOH/g.

400 g of this resin (A) was dissolved in 300 g of toluene, and while stirring, 2,4-tolylene diisocyanate 6
9g (0.8 in equivalent ratio to the amount of hydroxyl groups in resin (a))
was added dropwise, and the reaction was carried out at 65° C. for 11.5 hours under a nitrogen cloud. After confirming that no incyanate group remained by infrared absorption spectrum analysis, toluene was removed by distillation to obtain resin Nα1. The softening point of the resin Nα1 was 146.0°C, and the hydroxyl value was 20 mgKDH/g.

Reference Example 2 430 g of DCPD with a purity of 97%, 90 g of allyl alcohol (21.6 parts by weight per 100 parts by weight of DCPD), 360 K aromatic fraction with a boiling point range of 140 to 280°C produced by thermal decomposition of naphtha, and 120 g of mixed xylene. was stirred in an autoclave and reacted by heating at 260° C. for 2.5 hours, and treated in the same manner as in Reference Example 1 to obtain 596 g of resin (b). (The softening point of the sealant (b) was 87.5°C, and the hydroxyl value was 102 mg KDH/g.

Dissolve 400 g of this resin (B) in 300 g of toluene, stir, and dissolve 2.4-tolylene diisocyanate 5
1g (0.8 in equivalent ratio to the amount of hydroxyl groups in resin (b))
was added dropwise, and the reaction was carried out at 65°C for 11 hours under a nitrogen atmosphere.
Resin Nα2 was obtained by processing in the same manner as in Reference Example 1.

The softening point of resin No. 2 is 131.0°C, and the hydroxyl value is 1.
It was 6 mgKDH/g.

Reference Example 3 When producing ethylene, propylene, etc. by steam scrubbing naphtha, the 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% ocPo and 15% cyclopentadiene and isoprene or piperylene codimer.

658 g of this residue containing 85% DCPo, 42 g of 2-butene-1,4-diol (mixture of cis form and trans form) (7.5 parts by weight per 100 parts by weight of DCPo) and 300 g of mixed xylene were placed in an autoclave. The mixture was reacted by heating at 260° C. for 2.5 hours under stirring, and treated in the same manner as in Reference Example 1 to obtain 589 g of resin ()X).

The softening point of the resin (c) is 94.0°C, and the hydroxyl value is 70.4.
mg KOH/g.

400 g of this resin (c) was heated and melted at 140°C, and while stirring, 35 g of 2.4-) lylene diisocyanate (
The equivalent ratio of 0.8) to the amount of hydroxyl groups in the resin (c) was added dropwise, and the reaction was carried out for 2 hours in a nitrogen atmosphere.
Got 3. The softening point of the resin Nα3 was 125.5°C, and the hydroxyl value was 10 mg KOH/g.

Reference Example 4 631 g of DCPo with a purity of 97%, 69 g of allyl alcohol, and 300 g of mixed xylene were heated and reacted at 260°C for 2.5 hours while stirring in an autoclave, and treated in the same manner as in Reference Example 1 to obtain 590 g of resin (d). I got it. °
The softening point of resin (d) is 94.0°C, and the hydroxyl value is 70 m.
gKOH/g.

400 g of this resin (d) was heated and melted at 140°C, and while stirring, 34 g of hexamethylene diisocyanate (equivalent ratio of 0.8 to the amount of hydroxyl groups in resin (d)) was added dropwise, and the mixture was reacted for 3 hours under a nitrogen atmosphere. ) to obtain emulsion Nα4. Resin No. 4 had a softening point of 109.5° C. and a hydroxyl value of 21 mg Kn)I/g.

Reference Example 5 403 g of DCPo with a purity of 97%, aromatic fraction 22 with a boiling point range of 140 to 280°C produced by thermal decomposition of naphtha
6 g 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 6 500g of DCPo with a purity of 97% and 50g of mixed xylene
0 g was reacted by heating at 250° C. for 4 hours while stirring in an autoclave, and treated in the same manner as in Reference Example 1 to obtain 342 g of comparative resin. The softening point was 108°C.

Examples 1-4, Comparative Examples 1-2 Styrene-butadiene rubber (SBR1500) 100
12 parts by weight of each of the resins synthesized in Reference Examples 1 to 6
Parts by weight were used, and the other ingredients shown in Table 1 were mixed 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 follows. We considered gender. The results are shown in Table 1.

The various tests 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 tested using the rubber composition shown in Table 1.
0 R20 truck and bus tires were manufactured, and after driving 5000 km on rough roads with many protruding rocks such as in quarries, with frequent sudden braking, the tread surface became 100 ctd.
Evaluate the number of large cuts (scratches with a depth of 5 mm or more), small cuts (scratches with a depth of 1 or more and less than 5n++n), and chipping (a phenomenon in which small pieces of rubber with an area of 25 mm or more are scraped off). It was expressed as an index with Comparative Example 1 set as 100. The larger the value, the better.

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.

Examples 5 to 8, 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 higher the number of shifts, the better.

Table 2 Book 1 Mitsubishi Monsanto Chemical Co., Ltd. Anti-aging agent No. 2
As is clear from the table, even in natural rubber systems, the rubber compositions of the present invention have equivalent to significantly improved cut resistance, and significantly improved chipping resistance.

(Effects of the Invention) The rubber composition of the present invention, which is a combination of natural rubber and/or synthetic rubber with a specific fat (R2) containing an alkylidene norbornene unit, has extremely excellent cut resistance and chipping resistance. It is useful in the treads of tires, especially large tires that often travel on rough roads, 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)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, 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 Hydroxyl group-containing cyclopentadiene resin (R1) obtained by heating copolymerization with 2 to 120 parts by weight of component B, which is a compound having both
Furthermore, component C, which is a polyisocyanate compound, is reacted at a rate such that the equivalent ratio of the amount of isocyanate groups in component C to the amount of hydroxyl groups in the resin (R1) is within the range of 0.05 to 1.5. A rubber composition characterized in that 1 to 30 parts by weight of the resin (R2) obtained by the above are blended with 100 parts by weight of at least one rubber selected from the group consisting of natural rubber and synthetic rubber. . 2. Component A is cyclopentadiene, methylcyclopentadiene, syncropentadiene, cyclopentadiene-
The rubber composition according to claim 1, which is a 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. The rubber composition according to claim 1, wherein component C is an aliphatic polyisocyanate, an alicyclic polyisocyanate, a heterocyclic polyisocyanate, or an aromatic polyisocyanate.