JPH04225046A - rubber composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition having good processability and excellent rubber physical properties, which is prepared by blending a diene liquid resin with phenols added to solid rubber.

0002

[Prior Art] In the rubber industry, especially in the field of automobile tires, the aim is to achieve low fuel consumption and long life, and for this reason, there is little energy loss due to rolling resistance, heat generation, etc., excellent mechanical strength, and good workability. There is a demand for vulcanized rubbers of butadiene styrene rubber (hereinafter abbreviated as SBR) and natural rubber (hereinafter abbreviated as NR). However, in order to obtain SBR vulcanized rubber with excellent mechanical strength, for example, it is necessary to mix a large amount of adjuvants with SBR, which has strong green strength, but these do not only make the processability of SBR even more difficult. Therefore, large amounts of petroleum-based plasticizers and softeners must be added. However, in tires, when plasticizers and softeners bleed due to heat generated by the tires, especially when running at high speeds, the skid resistance of the tires decreases, which impairs the safety of automobiles and becomes a serious defect.

[0003] Butadiene acrylonitrile rubber (
NBR (hereinafter abbreviated as NBR) has highly polar acrylonitrile as a comonomer component in its molecular main chain, and has very good oil resistance, but is stiff due to strong intermolecular forces and is difficult to process.
Appropriate plasticizers and softeners often have to be used. Ester plasticizers for PVC and coal tar derivatives are generally used as plasticizers, but these weaken the stiffness of NBR during processing, but
It has a very large effect on the properties of vulcanizates. In other words, NBR vulcanized rubber is generally used in long-term contact with oils, solvents, etc., but the general plasticizers and softeners that are blended are extracted by the oils and solvents, reducing the physical properties of the vulcanized material. may cause unexpected trouble.

[0004] Also, a large amount of carbon black is blended as a reinforcing agent in order to improve wear resistance, but it is desirable that carbon black be uniformly dispersed, have a large contact area with rubber, and have a strong affinity. Generally, when carbon black is blended with rubber, the finer the particles of carbon black, the larger the number of particles and the larger the contact area with the rubber, which improves the abrasion resistance, tensile strength, etc. of the vulcanized rubber. but,
For the same particle size, the better the affinity between the carbon black surface and the rubber or rubber composition, the better these physical properties tend to be. For this reason, methods have been proposed in which a coupling agent is added to actively bond with carbon black.

[0005]

[Means for Solving the Problem] As a result of intensive research in view of the above-mentioned circumstances, the inventors of the present invention have found that by blending diene-based liquid resin with phenols added to carbon black compounded rubber, the processability of the rubber can be improved. that the physical properties of the rubber vulcanizate of the rubber, that is, energy loss such as rolling resistance and heat generation properties, and mechanical strength, etc., are significantly improved, when the conventional plasticizers and softeners mentioned above are used. The present inventors have discovered that the above drawbacks can be solved, and have completed the present invention.

That is, the present invention uses 0.2 to 30 parts by weight of a liquid resin obtained by adding phenols to a diene polymer or copolymer having a number average molecular weight of 300 to 10,000 per 100 parts by weight of solid rubber; carbon black 20~20
It relates to a rubber composition containing 0 parts by weight. By blending the above-mentioned diene-based liquid resin with added phenols (hereinafter referred to as phenol-added resin) into solid rubber,
By increasing compatibility and affinity with solid rubber and plasticizing or softening the solid rubber, processability is improved, affinity with carbon black is increased, and dispersibility of carbon black is improved. Further vulcanization causes the carbon-carbon double bonds of the phenol-added resin to co-vulcanize with the solid rubber, resulting in excellent rubber physical properties such as rolling resistance and heat generation, with little energy loss and improved mechanical strength. A vulcanized rubber that has high properties and is free from the above-mentioned problems such as bleeding can be obtained.

The solid rubber referred to in the present invention refers to SB containing 23.5% by weight of bound styrene, which is usually produced industrially.
Examples include NBR and NR having a bonded acrylonitrile content of about 25 to 46% by weight, including R, and chloroprene rubber (CR). Next, the phenol-added resin in the present invention is a conjugated diolefin polymer having a number average molecular weight of 300 to 10,000 or a conjugated diolefin copolymer having 50 mol% or more of conjugated diolefin units, and phenols added to it in a diene system. 0.02 to 100g of polymer or copolymer
1.0 mol was added.

The diene polymer or copolymer is a 1,3-
These include single or copolymers of butadiene, isoprene, and piperylene, and copolymers of diene and styrenes such as styrene, α-methylstyrene, and divinylbenzene, or acrylonitrile and acrylic esters. In addition to these, there are diene polymers or copolymers having hydroxyl groups at the terminals or side chains. Specifically, 1,2-type liquid polybutadiene, liquid polybutadiene having 1,2- and 1,4-bonds randomly, 1,4-type liquid polybutadiene, liquid polyisoprene, having hydroxyl group, cyan group. Examples include liquid polybutadiene.

Phenols include phenol, cresol,
Examples include monohydric phenolic compounds such as xylenol, and polyhydric phenolic compounds such as hydroquinone, resorcinol, and bisphenol A, but monohydric phenolic compounds are preferred, and phenol is more preferred. The method for introducing phenol into the above-mentioned diene polymer or copolymer is the known method described in JP-A No. 61-126162, i.e., using aluminum phenoxide as a catalyst to introduce phenol into the diene polymer or copolymer.
A method of heating to 0°C, preferably 170 to 250°C can be used. The appropriate amount of phenols to be introduced is 0.02 to 1.0 mol per 100 g of the diene polymer or copolymer (hereinafter referred to as phenolization rate of 0.02 to 1.0 mol/100 g). The above reaction can be carried out in the presence or absence of a solvent. Phenolization rate is 0.02
If it is less than 1.0 mol/100 g, the plasticizing effect is sufficient, but the physical properties of the vulcanized rubber are insufficient;
If the amount exceeds 0.00 g, the viscosity will become too high and the plasticizing effect and softening effect will decrease.

The average molecular weight of the diene polymer or copolymer of the present invention is from 300 to 10,000, more preferably from 50 to 10,000.
It is 0-3000. If the molecular weight is lower than 300, no improvement in the physical properties of the solid rubber vulcanizate can be expected, and if it exceeds 10,000, no effect of improving the processability of the solid rubber can be expected, so both are not preferred. The amount of the phenol-added resin is 0.2 to 30 parts by weight per 100 parts by weight of the solid rubber.
It is necessary to add 1 to 20 parts by weight, preferably 1 to 20 parts by weight. If it is less than 0.2 parts by weight, the effect of the present invention cannot be expected, and if it is added in excess of 30 parts by weight, the processability is improved, but the physical property balance of the solid rubber vulcanizate is disturbed and it is uneconomical. It is undesirable because it is

[0011] Carbon black has a particle size of 90 mμ or less,
Dibutyl phthalate (DBP) oil absorption 70ml/100
g or more are preferably used, such as F, FF,
Examples include furnace black such as FEF, GPF, SAFISAF, and SRF, and carbon black such as channel black. These carbon blacks have an affinity for phenol on their surface, and by blending them into solid rubber with phenol-added resins, their dispersibility in the rubber improves, reducing energy loss that occurs at the interface between the rubber and carbon black. The physical properties of the solid rubber vulcanizate are improved, and its reinforcing properties are further enhanced. The blending amount is 20 to 200 parts by weight per 100 parts by weight of solid rubber. If it is less than 20 parts by weight, physical properties such as mechanical strength and abrasion resistance of the solid rubber vulcanizate will decrease, and if it exceeds 200 parts by weight, processability will decrease and the physical property balance of the solid rubber vulcanizate will be disturbed. This is not desirable.

[0012] The rubber composition is used after being vulcanized. As the vulcanizing agent, known vulcanizing agents such as sulfur, organic peroxidants, sulfur-containing compounds, etc. can be used. There are no particular restrictions on the method of blending the vulcanizing agent into the rubber composition;
It can be carried out according to a known compounding method. The blending amount is not particularly limited, but for example, in the case of sulfur, it is in the range of 0.3 to 5 parts by weight per 100 parts by weight of solid rubber. By vulcanizing the rubber composition, crosslinking occurs between the solid rubber and the phenol-added resin, so that the rubber physical properties of the solid rubber vulcanizate can be further improved without impairing the processability of the rubber composition. .

[0013] Furthermore, known rubber chemicals such as vulcanization accelerators, antioxidants, adhesives, and peptizers may be added to the rubber composition as appropriate to the type, characteristics, and use of the solid rubber. be able to. Note that plasticizers such as petroleum softeners, phthalate esters, and polyesters may be used in combination as long as the effects of the present invention are not impaired. Each component of the rubber composition of the present invention can be kneaded using a general kneading method, such as a two-roll mixer, a Banbury mixer, an intensive mixer, etc., to obtain a solid rubber compound.

[0014] It can then be vulcanized by the conventional vulcanization methods described above. For example, vulcanization can be performed at, for example, 120 to 180° C. using a compression molding method using a hot press and a method of heating and vulcanizing directly or indirectly using steam.

[0015]

[Examples] Next, the present invention will be illustrated in more detail with reference to Examples. [Examples 1 to 3] Commercially available SBR rubber (JSR1500,
10 parts by weight of a phenol-added resin, 50 parts by weight of carbon black (HAF carbon), and other compounding agents were added to 100 parts by weight (manufactured by Japan Synthetic Rubber Co., Ltd.) as shown in Table 1, and kneaded. The kneading method was carried out using two 8-inch rolls at a roll surface temperature of 50±5° C. for about 20 minutes. Thereafter, it was subjected to an unvulcanized rubber test and a vulcanized rubber test, and the results are shown in Table 2. The Mooney viscosity of the unvulcanized rubber was determined by 1 minute of preheating and 4 minutes of rotor rotation, and the vulcanization test showed the time to reach 10% and 90% of the hardness increase Δh due to vulcanization (scorch time). Vulcanized rubber physical properties are 14
Each measurement was made using a sheet press-vulcanized under vulcanization conditions of 5° C. for 40 minutes. The tensile modulus of vulcanized rubber is 100%
The tensile strength was measured by the maximum tensile stress, the elongation was measured by the maximum elongation, the hardness was measured by the ASTM-A method, and the abrasion resistance was measured by the Akron A wear amount.

The phenol-added resin of Examples 1 and 2 was a liquid resin obtained by adding phenol to liquid polybutadiene having an average molecular weight of 700 (Nisseki Polybutadiene P-700-300).
, phenol addition rate 300 mmol/100 g, manufactured by Nippon Petrochemical Co., Ltd.) was used. The phenol-added resin of Example 3 was prepared by adding 2,
Liquid resin added with 4-xylenol (P-1000 as above)
-500X, xylenol addition rate 500 mmol/10
0g) was used.

[Comparative Examples 1 to 3] The same procedure as in Examples 1 to 3 was carried out, except that in Comparative Example 1, no phenol-added resin was added.
In Comparative Example 2, a petroleum softener (Comolex 700, manufactured by Nippon Oil Co., Ltd.) was used instead of the phenol-added resin. In Comparative Example 3, the phenol addition resin of Example 1 was added to 0.1
Parts by weight. These compounding ratios and rubber test results are also listed in Tables 1 and 2.

[Examples 4 to 6] Commercially available NBR for solid rubber
Rubber (Nipol 1042, manufactured by Nippon Zeon Co., Ltd.)
Examples 1-3 were repeated using However, the physical properties of the vulcanized rubber were measured using sheets press-vulcanized under vulcanization conditions of 145° C. for 20 minutes. The recipe and measurement results are shown in Tables 3 and 4.

[Comparative Examples 4 to 6] Same NB as Examples 4 to 6
Comparative Examples 1-3 were repeated using R rubber. However, in Comparative Example 5, the plasticizer DOP was used instead of the phenol-added resin. For the physical properties of the vulcanized rubber, a sheet press-vulcanized under vulcanization conditions of 145° C. for 20 minutes was used. The recipe and measurement results are also listed in Tables 3 and 4.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[0020]

Effects of the Invention According to the present invention, by blending a phenol-added resin with carbon black into solid rubber, the processability of the compound is improved, and the physical properties of the vulcanized rubber, such as rolling resistance and heat generation properties, are improved. A rubber composition with significantly improved energy loss, mechanical strength, etc. can be obtained. In other words, the blending of phenol-added resin not only provides the effect as a softener or plasticizer to solid rubber, but also has a good affinity with carbon black because it has a phenolic hydroxyl group in the molecule. It improves the physical properties of the solid rubber vulcanizate, such as improving the dispersibility of the rubber and reducing the energy loss that occurs at the interface between the rubber and carbon black, and further enhances the reinforcing properties of the carbon black. Further, the obtained vulcanized rubber does not cause bleeding or blooming over a long period of time as a result of crosslinking between the phenol-added resin and the solid rubber during vulcanization, and has further excellent rubber physical properties.

Claims (5)

[Claims] [Claim 1] (a) Solid rubber

100 parts by weight (b) Number average molecular weight 300-10,00
Liquid resin made by adding phenols to a diene polymer or copolymer of 0.
0.2 to 30 parts by weight and (c) carbon black
A rubber composition comprising 20 to 200 parts by weight. 2. The rubber composition according to claim 1, wherein the solid rubber is one or more solid rubbers selected from the group consisting of butadiene styrene rubber, butadiene acrylonitrile rubber, natural rubber, and chloroprene rubber. . 3. The rubber composition according to claim 1 or 2, wherein the diene in the diene polymer or copolymer is butadiene. 4. The rubber composition according to claim 1, 2 or 3, wherein the phenol is phenol. 5. The amount of phenol added is 0.02 to 1.0 mol per 100 g of the diene polymer or copolymer. rubber composition.