JPH0672196B2 - Rubber composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber composition, particularly a specific hydroxyl group modified with at least one compound selected from polyisocyanates, polybasic acids, their anhydrides and their esters. The present invention relates to a rubber composition having improved cut resistance and chipping resistance by compounding a contained cyclopentadiene resin.

(Prior Art) Large tires for heavy duty trucks / buses that often run on unpaved roads, especially on rough roads where rocks are exposed, or off-the-road tires used at quarry sites, etc. There is a lot of opportunity to receive cuts in the parts and sidewalls, and these cuts tend to grow and damage the tire, or rainwater and the like that infiltrate from the cuts corrode the steel cord reinforcing material and cause tire damage. Therefore, there is a need for a rubber composition having excellent cut resistance and chipping resistance, especially in the tread portion of the tire.

In general, a method of highly filling carbon black is used as a means for improving the cut resistance of a rubber composition, but the cut resistance is improved by this method, but it is required in running on rough roads like the cut resistance. However, there is a problem that the chipping resistance and the heat generation property are remarkably inferior, and the kneading and extrusion workability is remarkably inferior.

On the other hand, in Japanese Patent Publication No. 48-38615, which is one of the applicants of the present invention, a dicyclopentadiene resin having a softening point of 50 to 200 ° C. and a bromine number of 40 to 150 is blended with a styrene-butadiene copolymer rubber. Although it is described that the cut resistance of the rubber composition can be improved, the cut resistance was considerably improved by this, but there was a drawback that the chipping resistance was still poor.

(Problems to be Solved by the Invention) In order to solve such problems, the present applicants in Japanese Patent Application No. 61-24963 and Japanese Patent Application No. 61-142967 disclose 5-alkylidene norbornene-2 or It has been proposed to blend a cyclopentadiene resin modified with the derivative or a cyclopentadiene resin modified with a polyisocyanate compound into the rubber composition, but it is extremely important to further improve the cut resistance and chipping resistance. .

Therefore, an object of the present invention is to provide a very useful rubber composition which exhibits remarkably excellent cut resistance and chipping resistance when used for a tread of a large tire or an off-the-road tire that travels on a rough road. is there.

(Means for Solving the Problems) As a result of intensive studies to solve the above problems, the present inventors have found that a compound having a cyclopentadiene ring or a Diels-Alder adduct thereof and 5-alkylidene norbornene-2. And at least one compound selected from polyisocyanates, polybasic acids, their anhydrides and their esters in a hydroxyl group-containing cyclopentadiene resin obtained by copolymerizing a compound having both a polymerizable double bond and a hydroxyl group in the molecule. If the resin obtained by reacting
It was confirmed that the above problems could be solved, and the present invention was achieved.

That is, the present invention has the general formula (In the formula, R is an alkyl group having 1 to 3 carbon atoms, and m is 0.
Is an integer from 6 to 6. 100 parts by weight of component A, which is at least one compound selected from the group consisting of a compound having a cyclopentadiene ring represented by the formula (1) and a Diels-Ahnder adduct thereof, (Wherein R ¹ R ² and R ³ are hydrogen atoms or alkyl groups having 1 to 3 carbon atoms, and n is 0 or 1)
Alkylidene norbornene-2 or a derivative thereof, which was obtained by heat-copolymerizing 15 parts by weight of component B2 to 15 parts by weight and component C1 to 120 parts by weight of a compound having both a polymerizable double bond and a hydroxyl group in the molecule. Component D, which is at least one compound selected from the group consisting of polyisocyanates, polybasic acids, their anhydrides and their esters, is added to the hydroxyl group-containing cyclopentadiene resin (R1) and the amount of isocyanate groups in component D and / or Alternatively, the equivalent ratio of the amount of carboxyl group and / or the amount of acid anhydride group (one acid anhydride group is divalent) and / or the amount of ester group to the amount of hydroxyl group of the resin (R1) is in the range of 0.05 to 1.5. Resin (R
2) to 1 to 30 with respect to 100 parts by weight of at least one rubber selected from the group consisting of natural rubber and synthetic rubber.
The present invention relates to a rubber composition characterized by being mixed in parts by weight.

In the present invention, the synthetic rubber, synthetic polyisoprene rubber, polybutadiene rubber, styrene butadiene rubber,
Butyl rubber, halogenated butyl rubber, ethylene propylene terpolymer, acrylonitrile butadiene rubber and the like, which may be used alone or as a blend. Natural rubber may also be used alone and in a blend with at least one rubber of the above synthetic rubbers.

In the present invention, the component A includes a compound of the general formula I, for example, cyclopentadiene, methylcyclopentadiene and the like, and a Diels-Alder adduct of the compound of the general formula I, for example, dicyclopentadiene, cyclopentadiene-methylcyclo Pentadiene codimer,
Examples thereof include tricyclopentadiene, and these and mixtures thereof are industrially preferably used, and among these, cyclopentadiene, dicyclopentadiene, or a mixture of both is particularly preferable.

High purity of cyclopentadiene, dicyclopentadiene or an alkyl-substituted derivative thereof is not necessarily required, but 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, C _{5 of by-} product oil of high temperature pyrolysis such as naphtha
By dimerizing cyclopentadiene and methylcyclopentadiene contained in the fraction by thermal dimerization, dicyclopentadiene, dimethylcyclopentadiene, cyclopentadiene-methylcyclopentadiene co-dimer, cyclopentadiene-isoprene co-dimer, cyclopentadiene It is possible to use a concentrated fraction obtained by removing most of C ₅ components such as C ₅ olefin and C ₅ paraffin by distillation after forming a mixture of piperylene co-dimer and the like.

Examples of the component B include 5-ethylidene norbornene-2, 5-ethylidene methyl norbornene-2, 5
-Ethylidene dimethyl norbornene-2, 5-propylidene norbornene-2, 5-isopropylidene norbornene-2 and the like may be mentioned. These may be used as a mixture of two or more kinds, and among these, 5-ethylidene Norbornene-2 is preferred because it can be easily obtained industrially.

Component C, 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,
Unsaturated alcohols such as methylpropenylcarpinol, unsaturated dihydric alcohols such as 2-butene 1,4-diol, 3-hexene-2,5-diol, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, etc. Hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and other hydroxyalkyl methacrylates and the like, which can be thermally copolymerized with component A, and a hydroxyl group-containing unsaturated compound having 3 to 22 carbon atoms, and these 2 Includes mixtures of more than one type.

The hydroxyl group-containing cyclopentadiene resin (R1) used in the present invention is based on the above component A of 100 parts by weight, component B2 to 150 parts by weight, preferably 5 to 100 parts by weight and component C1 to 120 parts by weight, preferably 2 to 100 parts by weight. Part can be produced by heating at 150 to 300 ° C., preferably 200 to 280 ° C. for 10 minutes to 20 hours, preferably 1 hour to 15 hours without catalyst.

In the resin (R2) used in the present invention, the ratio of the component B or the component C to the component A in the copolymerization reaction carried out for its production is extremely important, and the amount of the component B is 2 parts with respect to 100 parts by weight of the component A. If the weight part or the amount of the component C is less than 1 part by weight, the rubber plastic product finally obtained has insufficient cut resistance and chipping resistance, and the amount of the component B is 150 parts by weight or the component. If the amount of C exceeds 120 parts by weight, hydroxyl group-containing cyclopentadiene resin (R1)
The yield of the resin (R2) is extremely lowered, the softening point of the resin (R2) is also lowered, the cut resistance is rather lowered, and the refining workability is deteriorated due to blocking of the resin (R2).

In addition, the above-mentioned hydroxyl group-containing cyclopentadiene resin (R1)
In the production, it is also possible to use an unsaturated component in the petroleum fraction, especially an unsaturated aromatic component, in an amount equal to or less than that of the component A. For example, styrene, α-methylstyrene,
Vinyltoluene, indene, methylindene, and a mixture thereof can be used, and industrially, a so-called C ₉ fraction produced as a by-product upon decomposition of naphtha or the like is preferable.

By using such an unsaturated component in the petroleum fraction in combination, it is possible to improve the performance of the rubber composition to some extent. For example, in combination with styrene or the like, it is possible to further improve the cut resistance. In this case, there is no change in the usage amount range of the component B and the component C with respect to the component A.

The polyisocyanate compound of the component D is an aliphatic polyisocyanate, an alicyclic polyisocyanate, a heterocyclic polyisocyanate or an aromatic polyisocyanate, for example, 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-tolylene 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, 1-methoxyphenylene-2,4- Diisocyanate, benzene-1,2,4
-Triisocyanate, tolidine diisocyanate and the like can be mentioned, and a mixture of two or more kinds of these can also be used.

Further, the polybasic acid, its anhydride and its ester of the component D means an aliphatic polybasic acid, its anhydride and its ester, an alicyclic polybasic acid, its anhydride and its ester,
Aromatic polybasic acids, their anhydrides and their esters, such as adipic acid, sebacic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, dimethyl maleate, tetrahydrophthalic acid, 3,6-endomerene. Examples include tetravidrophthalic anhydride, dimethyl tetrahydrophthalate, phthalic acid, isophthalic acid, phthalic anhydride, tetrachlorophthalic anhydride, trimellitic anhydride, dimethyl terephthalate, etc. Use a mixture of two or more of these. You can also

The reaction between the hydroxyl group-containing cyclopentadiene resin (R1) and the component D is at 20 to 300 ° C, preferably 30 to 280 ° C for 10 minutes to
It is carried out for 20 hours, preferably 30 minutes to 15 hours. The amount of the component D used is such that the amount of isocyanate group and / or the amount of carboxyl group and / or the amount of acid anhydride group (one acid anhydride group is divalent) and / or the amount of ester group is a hydroxyl group-containing cyclohexyl group. The equivalent ratio is 0.05 to 1.5, preferably 0.1 to 1.2 with respect to the amount of hydroxyl groups in the pentadiene resin (R1).

When the amount of component D is less than the corresponding amount ratio of 0.05, almost no effect of increasing the molecular weight of the resin (R1) is observed, and the cut resistance of the finally obtained rubber composition is insufficient. Is. Further, when the equivalent ratio exceeds 1.5, there is a drawback that the change with time of the resin is remarkable due to the effect of the residual polar group such as the residual isocyanate group or the carboxyl group, or the vulcanization rate of the rubber composition is significantly reduced. Occurs.

Further, in the case of the polybasic acid ester of the component D, the reaction can be efficiently carried out by using an ester exchange catalyst such as calcium acetate, lead acetate, aluminum alkoxide or the like.

The resin (R2) used in this invention is a ring and ball method (JIS K253
1-60), the softening point is 50-190 ℃, especially 7
It is preferably in the range of 0 to 180 ° C. When the softening point is lower than 50 ° C., the modulus of the rubber composition under low elongation is lowered, and not only the cut resistance is deteriorated, but also the resin is blocked and the refining workability tends to be deteriorated. On the other hand, when the temperature is higher than 190 ° C, it becomes difficult to uniformly disperse in rubber.

The amount of the resin (R2) used in the present invention is
1 to 30 parts by weight, preferably 3-1 to 100 parts by weight of rubber
5 parts by weight. If the blending amount is less than 1 part by weight, the effect of the addition is not exerted, and the cut resistance and chipping resistance are not improved. On the other hand, when 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 remarkably deteriorated.

In the present invention, in addition to the resin (R2), compounding agents usually used in the rubber industry, for example, reinforcing filler, vulcanizing agent, vulcanization accelerator, vulcanization accelerating aid, softening agent, aging Inhibitors and the like can be appropriately added.

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

Reference Example 1 600 g of dicyclopentadiene (DCPD) with a purity of 97%, purity of 98
% 5-ethylidene norbornene-2 (ENB) 67 g (DCPD
11.2 parts by weight to 100 parts by weight), 33 g of allyl alcohol
(5.5 parts by weight with respect to 100 parts by weight of DCPD) and 300 g of mixed xylene were charged into an autoclave 2 and heated at 260 ° C. for 5 hours under stirring in a nitrogen atmosphere. After heating,
Cool the autoclave and distill the contents to remove unreacted monomers, low polymers and xylene, leaving 63
7 g of resin (a) was obtained. The softening point of resin (a) is 142.0
The hydroxyl value at 48 ° C was 48 mgKOH / g.

500 g of this resin (a) was dissolved in 300 g of toluene, and 29.8 g of 2,4-tolylene diisocyanate (equivalent ratio to 0.8 of the amount of hydroxyl groups of resin (a) was added dropwise under stirring. The reaction was carried out at ℃ for 11.5 hours. After confirming that no isocyanate group remained by infrared absorption spectrum analysis, toluene was removed by distillation to remove resin N
I got o.1. Resin No. 1 has a softening point of 156.0 ° C and a hydroxyl value of 10
It was mgKOH / g.

Reference Example 2 DCPD 500 g with a purity of 97%, ENB 67 g with a purity of 98% (13.4 parts by weight to 100 parts by weight of DCPD), allyl alcohol 33 g (DCPD100
6.6 parts by weight relative to parts by weight) 140 generated by thermal decomposition of naphtha
200g aromatic fraction and mixed xylenes in the boiling range of ~ 280 ℃
00 g was heated and stirred at 260 ° C. for 7 hours in an autoclave with stirring and treated in the same manner as in Reference Example 1 to obtain 662 g of a resin (b). The softening point of the resin (b) was 137.5 ° C, and the hydroxyl value was 48 mgKOH / g.

500 g of this resin (b) was dissolved in 300 g of toluene, and under stirring, 37.3 g of 2,4-tolylene diisocyanate (equal ratio 1.0 to the amount of hydroxyl groups of resin (b)) was added dropwise. The reaction was carried out at 11 ° C. for 11 hours, and the same treatment as in Reference Example 1 was carried out to obtain Resin No. 2. Resin No. 2 has a softening point of 147.5
C., hydroxyl value was 6 mg KOH / g.

Reference Example 3 When producing ethylene, propylene, etc. by steam cracking of naphtha, a C ₅ decomposition fraction (boiling point 28-
(60 ° C.) is heated at 120 ° C. for 4 hours and the C ₅ fraction is removed by distillation to give a residue containing 85% DCPD and 15% cyclopentadiene and isoprene or piperylene co-dimer. 613g residue containing this DCPD 85%, purity 98%
58 g of ENB (11.1 parts by weight per 100 parts by weight of DCPD), 2-butene-1,4-diol (mixture of cis and trans forms) 2
9g (5.6 parts by weight for 100 parts by weight of DCPD) and mixed xylene
300 g of the resin was heated in an autoclave with stirring at 260 ° C. for 4 hours, and treated in the same manner as in Reference Example 1 to obtain 559 g of a resin (c). The softening point of the resin (C) was 119.0 ° C, and the hydroxyl value was 62 mgKOH / g.

500 g of this resin (c) was heated and melted at 140 ° C, and under stirring, 43.3 g of 2,4-tolylene diisocyanate (resin (c))
Resin (No. 3) was obtained by adding 0.9) in an equivalent ratio with respect to the amount of hydroxyl groups of, and reacting in a nitrogen atmosphere for 2 hours. Resin No. 3 had a softening point of 142.5 ° C and a hydroxyl value of 8 mgKOH / g.

Reference Example 4 500 g of the resin (a) obtained in Reference Example 1 and 33.2 g of dimethyl terephthalate (equivalent ratio to the amount of hydroxyl groups of the resin (a) were 0.
8) and 0.9 g of zinc acetate were placed in a 1.5-necked three-necked flask and blown with nitrogen to remove methanol, and then at 4 ° C at 200 ° C.
The reaction was carried out over time. After completion of the reaction, residual methanol was removed by distillation to obtain Resin No. 4. Resin No. 4 has a softening point of 151.0
The hydroxyl value was 11 mgKOH / g at ℃.

Reference Example 5 500 g of the resin (c) obtained in Reference Example 3 and 42.9 g of dimethyl terephthalate (equivalent ratio to the amount of hydroxyl groups of the resin (c) were 0.
8) and 1.2 g of zinc acetate are placed in a 1.5-necked 3-neck flask and blown with nitrogen to remove methanol, and
After reacting for a time, the same treatment as in Reference Example 4 was carried out to obtain Resin No. 5. Resin No. 5 has a softening point of 140.5 ° C and a hydroxyl value of 13 mgKOH
It was / g.

Reference Example 6 DCPD 403 g with 97% purity 140-280 produced by thermal decomposition of naphtha
226g of aromatic fraction and 371g of mixed xylene in boiling range of ℃
Was heated in an autoclave under stirring at 260 ° C. for 3 hours and treated in the same manner as in Reference Example 1 to give 490 g of the comparative resin a.
Got The softening point was 131 ° C.

Reference Example 7 500 g of DCPD having a purity of 97% and 500 g of mixed xylene were reacted by heating at 250 ° C. for 4 hours under stirring in an autoclave,
The same treatment as in Reference Example 1 was carried out to obtain 342 g of Comparative Resin b. The softening point was 108 ° C.

Examples 1 to 5, Comparative Examples 1 to 2 12 parts by weight of each of the resins synthesized in Reference Examples 1 to 6 was used with respect to 100 parts by weight of styrene-butadiene rubber (SBR1500).
Others were compounded with the ingredients shown in Table 1 and kneaded in a Banbury mixer, followed by vulcanization, and the following cut resistance and tread appearance when these rubber compositions were used for a tire tread were examined. The results are shown in Table 1.

The various tests are as follows.

(A) Cut resistance A pendulum type impact cut tester hits a steel blade from a certain height to scratch it, and the depth of the cut is measured. displayed. The larger the value, the better the cut resistance.

(B) Tread appearance test Divide the tread into 4 parts and use the rubber composition shown in Table 1 to 1000R2
We made 0 truck and bus tires, and applied 5000 km while frequently applying sudden braking on rough roads with many protruding rocks such as quarries.
After running, a large cut per 100 cm ^{2 of} tread surface (depth 5 m
Number of scratches (m or more), small cut (scratches with a depth of 1 mm or more and less than 5 mm)
The number and the number of chippings (a phenomenon in which a small piece of rubber having an area of 25 mm ² or more was scraped off) were evaluated, and Comparative Example 1 was set as 100 and indicated by an index. The larger the value, the better.

As is clear from Table 1, the rubber composition of the present invention has remarkably improved cut resistance and remarkably improved chipping resistance.

Examples 6 to 10 and Comparative Examples 3 to 4 Rubber compositions were prepared with the compounding contents shown in Table 2 and evaluated in the same manner as in Example 1. The results are shown in Table 2. In addition, the results are shown by an index with Comparative Example 3 being 100, and similarly, the larger the value, the better.

As is clear from Table 2, even in the natural rubber system, the rubber composition of the present invention has remarkably improved cut resistance and remarkably improved chipping resistance.

(Effects of the invention) As described above, a hydroxyl group-containing cyclopentadiene resin obtained by reacting natural rubber and / or synthetic rubber with 5-alkylidene norbornene-2 is prepared from polyisocyanate, polybasic acid, its anhydride and its ester. This rubber composition containing a specific cyclopentadiene resin modified with at least one compound selected from the group consisting of the following groups is remarkably excellent in cut resistance and chipping resistance, and therefore tires, especially on rough roads It is useful for treads of large tires that run frequently, but can also be used for tire sidewalls and many other parts thereof, or other rubber products such as conveyor belts and hoses.

Claims (5)

[Claims] 1. A general formula (In the formula, R is an alkyl group having 1 to 3 carbon atoms, and m is 0.
A compound having a cyclopentadiene ring represented by the formula: and a Diels-Alder adduct thereof, which is at least one compound selected from the following formula: (Wherein R ¹ , R ² and R ³ are hydrogen atoms or alkyl groups having 1 to 3 carbon atoms, n is 0 or 1)
Hydroxyl group obtained by heat-copolymerizing alkylidene norbornene-2 or a derivative thereof, component B2 to 150 parts by weight, and component C1 to 120 parts by weight, which is a compound having both a polymerizable double bond and a hydroxyl group in the molecule. Component D, which is at least one compound selected from the group consisting of polyisocyanates, polybasic acids, their anhydrides and their esters, is added to the contained cyclopentadiene resin (R1) and the amount of isocyanate groups in component D and / or Reaction with an equivalent ratio of the amount of carboxyl groups and / or the amount of acid anhydride groups (one acid anhydride group is divalent) and / or the amount of ester groups to the amount of hydroxyl groups of the resin (R1) in the range of 0.05 to 1.5 1 to 30 parts by weight of the resin (R2) thus obtained is mixed with 100 parts by weight of at least one rubber selected from the group consisting of natural rubber and synthetic rubber. And a rubber composition. 2. The rubber composition according to claim 1, wherein the component A is cyclopentadiene, methylcyclopentadiene, dicyclopentadiene, cyclopentadiene-methylcyclopentadiene co-dimer or tricyclopentadiene. 3. Component B is 5-ethylidene norbornene-
The rubber composition according to claim 1, which is 2,5-ethylidenemethylnorbornene-2, 5-ethylidenedimethylnorbornene-2, 5-propylidenenorbornene-2 or 5-isopropylidenenorbornene-2. 4. The rubber composition according to claim 1, wherein the component C is an unsaturated alcohol having 3 to 22 carbon atoms, an unsaturated dihydric alcohol, a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate. object. 5. Component D is an aliphatic polyisocyanate, an alicyclic polyisocyanate, a heterocyclic polyisocyanate,
The rubber according to claim 1, which is an aromatic polyisocyanate, an aliphatic polybasic acid, an alicyclic polybasic acid, an aromatic polybasic acid, an anhydride of these polybasic acids or an ester of these polybasic acids. Composition.