JPH0655854B2 - Tires for passenger cars - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a high elastic modulus and a Mooney viscosity (ML).
The present invention relates to a passenger car tire using a rubber composition having a small size and excellent processability as a cap tread rubber.

[Industrial field of application] Generally, tires are required to have excellent handling properties, durability, and the like, and in particular, they are required to have excellent wet skid resistance on wet road surfaces in terms of safety. Further, based on the social demand for resource saving in recent years, in order to reduce the dynamic loss of tires, research and development of tires with low rolling resistance, that is, tires with low energy loss are being conducted. The energy loss consumed by a free-rotating tire varies depending on the tire structure, etc., but about half of the total is consumed in the tread portion. Therefore, if the internal consumption of the tread rubber is reduced, the energy loss at the time of rolling of the tire is reduced, and a tire with low rolling resistance can be obtained.

Therefore, it has been attempted to modify the tread rubber so as to reduce the energy loss. However, such rubber modification tends to reduce wet skid resistance.
Since the improvement of rolling resistance and the improvement of wet skid resistance are generally contradictory matters, various attempts have been made to improve the tire structure in order to make them compatible. One of the measures is to make the tread into two layers, that is, a cap tread and a paste red. That is, a cap tread having a good wet skid resistance and a paste red having a small energy loss are provided in two layers to increase the wet skid resistance of the tire and reduce the energy loss as a whole.

In addition to wet skid resistance and abrasion resistance, the cap tread rubber is required to have a high elastic modulus due to high-speed running property and a low viscosity that easily flows to every corner of the complicated tread pattern of the mold.

According to the present invention, a rubber composition having a small Mooney viscosity and excellent processability can be obtained in spite of the high elastic modulus of the vulcanized product,
By using this composition for a cap tread, a tire having good wet road surface gripping property and abrasion resistance can be manufactured.

[Prior Art] Various methods have hitherto been attempted to obtain a rubber having a high elastic modulus. The method of blending a large amount of carbon black is not preferable because the cohesion of rubber in the processing step is poor, the electric power load is increased during kneading and extrusion, and the compound ML becomes large, which causes difficulties during tire molding. . The method of blending a large amount of sulfur has drawbacks such as the plume of sulfur and the crack growth being accelerated due to an increase in crosslink density. When the thermosetting resin is added, since the thermosetting resin has a low compatibility with the normally used natural rubber and diene rubber, it is difficult to obtain a good dispersion when it is added in a large amount. Further, since this kneaded material is hard even when it is not vulcanized, the load becomes large during kneading and extrusion, and the workability of tire molding becomes poor. In the method of simply blending the short fibers, the creep is increased or the fatigue life is shortened because the short fibers and the rubber are not sufficiently bonded.

[Problems to be Solved by the Invention] The present invention has excellent moldability and high speed by blending a special rubber composition with the drawbacks such as low productivity and low abrasion resistance of the conventional technology. An object of the present invention is to provide a passenger car tire having good running property, wet road surface grasping property, and wear resistance.

[Means for Solving Problems] That is, according to the present invention, fine short fibers of a fiber-forming polyamide are embedded in a vulcanizable rubber, and vulcanization with the polyamide is possible at an interface of the fiber. A reinforced rubber composition (A) in which a rubber is bonded via a silane coupling agent, a diene rubber (B), and carbon black (C) are blended, and the following (I) to (IV)
The present invention relates to a tire for passenger cars, which is characterized in that a rubber composition satisfying the above condition is used in a cap tread portion.

(I) The amount of the polyamide is 1 to 15 parts by weight based on 100 parts by weight of all rubber components, and (II) the ratio of natural rubber and / or polyisoprene in the components (A) and (B) is all. 5-40 for rubber component
%, (III) the amount of carbon black is 60 to 90 parts by weight based on 100 parts by weight of the total rubber component, and (IV) the 300% modulus of the vulcanizate of the rubber composition is 100 Kg / cm ^2. That is all.

The rubber composition for cap tread used in the present invention,
Mooney viscosity ML _{1 + 4} (100
Since it has a small temperature (° C) and excellent workability and fluidity, it easily flows to every corner of the complicated tread pattern of the mold, and also has good wet skid resistance and wear resistance.

In this invention, fine short fibers of a fiber-forming polyamide are embedded in a vulcanizable rubber, and at the interface of the fibers, the polyamide and the vulcanizable rubber are mediated by a silane coupling agent. It is necessary to blend a reinforced rubber composition that is bonded together, and thereby a rubber composition having excellent moldability can be produced despite blending fibers into the polymer, and this composition can be used as a cap tread. It can be used to produce tires with good wet road grip and good wear resistance.

Hereinafter, the rubber composition for a cap tread of the present invention will be described in detail.

Examples of the vulcanizable rubber used in the reinforced rubber composition constituting the rubber composition for a cap tread of the present invention include natural rubber, cis-1.4 polybutanediene, polyisobrene, styrene-butadiene copolymer rubber and isobrene. −
Examples thereof include isobutylene copolymer, and natural rubber is preferable among these rubbers.

Further, the polyamide used in the reinforced rubber composition,
It is capable of forming fibers and has a melting point of 150 to 260 ° C, preferably 190 to 235 ° C, nylon 6, nylon 61
0, nylon 12, nylon 611, nylon 612,
Examples thereof include nylon 66 and copolymers thereof. The polyamide is not particularly limited as long as it has a fiber-forming ability, but has a number average molecular weight of 5,000 or more, preferably 8,000 or more. If the molecular weight is too low, the fiber-forming ability is poor and the strength is low.

Short fibers used in the reinforced rubber composition of the present invention,
The above-mentioned polyamide fine short fibers, in which the short fibers have a form in which molecules are arranged in the fiber axis direction, and the average diameter thereof is preferably 0.05 to 0.8 µ, particularly a circular cross section and the shortest fiber length. Is preferably 1 μm or more.

The silane coupling agent used in the reinforced rubber composition has a structural formula of Y—R ₁ SiX ₃ or Y—.
The compound represented by R ₁ SiR ₂ X ₂ is used.

Here, Y, R ₁ , R ₂ and X each represent the following groups.

_{R 1: A P C n H} 2n B Q C m H 2m B Q C l H 2l A: C 6 H 4 P = 0~2 n = 0~5 B: O, NH Q = 0~2 m = 0 _{~5 l = 0~5 R 2: C} n H 2n + 1 n = 1~4 X: D r C n H 2n E s C m H 2m + 1 D: O, Cl r = 0~2 n = 0 ~ 5 E: Os = 1-2 m = 1-5 Specifically, γ-aminopropyltrimethoxysilane, γ
-Aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-
β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ- (diethylenetriamino) propyltrimethoxysilane, γ-ureate-propyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (βmethoxyethoxy) silane , Γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, β
-(3.4 epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, N-phenyl-
γ-aminopropyltrienoxysilane, N-β (N-
Vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride group and the like can be preferably used.

Further, the ratio of the weight of the vulcanizable rubber to the weight of the fine polyamide short fibers embedded in the vulcanizable rubber (vulcanizable rubber / fine polyamide short fibers) is 1
It is preferable that the polyamide forming the short fibers and the vulcanizable rubber are bonded to each other via a silane coupling agent so as to be 0 to 30% by weight, particularly 15 to 30% by weight.

The above-mentioned reinforced rubber composition used in the present invention is produced, for example, as follows. The vulcanizable rubber, 5 to 100 parts by weight of polyamide per 100 parts by weight of the vulcanizable rubber, and 0.1 to 5.5 parts by weight of a silane coupling agent per 100 parts by weight of the polyamide are added to the melting point of the polyamide. Kneading at the above temperature, by extruding the resulting kneaded product at a temperature of the melting point of the polyamide or higher, or further, appropriately stretch the extrudate at a temperature higher than or lower than the melting point of the polyamide Is obtained by Furthermore,
It can also be obtained by using these stretching methods together.

The rubber composition for cap tread used in the present invention,
It is prepared by blending the reinforced rubber composition (A), the diene rubber (B), and the carbon black (C).

Examples of the diene rubber (B) include natural rubber and cis-
1.4-polyisoprene, cis-1.4 polybutadiene, styrene-butadiene copolymer rubber, isoprene-
Examples include isoptylene copolymers.

As the carbon black, those having a particle diameter of 90 mμ or less and a dibutyl phthalate (DBP) oil absorption amount of 70 ml / 100 g or more are preferably used. As carbon black, for example, HAF, FF, FEF, GPE, SAF, I
Various carbon blacks such as SAF and SRF are used.

The amount of each component, (I) the polyamide (short fibers) is 1 to 15 parts by weight, preferably 2 to 15 parts by weight, based on 100 parts by weight of the total of the rubber components, and the ratio of (II) rubber is The total amount of the natural rubber or polyisoprene in the component (A) and the component (B) is 5 to 40% by weight,
The amount of I) carbon black is 60 to 90 parts by weight based on 100 parts by weight of the total rubber component, and the vulcanized product of the (IV) composition has a 300% elastic modulus defined by JIS K6301 of 100 Kg / cm ^2. It is mixed so as to satisfy the above conditions. If the amount of carbon black is less than the lower limit, the elastic modulus of the vulcanizate will decrease, while if it is greater than the upper limit, the Mooney viscosity will tend to be too high and tire moldability will tend to deteriorate. Further, if the proportion of the rubber is out of the above range, the vulcanized product has poor pico-abrasive properties and wet skid resistance.

The rubber composition used in the present invention is prepared by mixing each of the above components with a kneading machine such as a Banbury mixer or a roll extruder in an amount of 50 to 1
It can be obtained by kneading at 80 ° C. for about 1 to 60 minutes. Additives such as a vulcanizing agent are added to the rubber composition.

As the vulcanizing agent, known vulcanizing agents such as sulfur, organic peroxides, and sulfur-containing compounds can be used. The method of compounding the vulcanizing agent with the rubber composition is not particularly limited, and a compounding method known per se can be adopted. Along with vulcanizing agents, white carbon, activated calcium carbonate, ultrafine magnesium silicate, high styrene resin, coumarone indene resin, phenol resin, lignin, modified melamine resin, petroleum resin and other reinforcing agents, various grades of calcium carbonate, base Fillers such as soluble magnesium carbonate, clay, zinc white, diatomaceous earth, reclaimed rubber, powdered rubber, ebonite powder, aldehydes, ammonia, aldehydes, amines, guanidines, thioureas, thiazoles, thiurams, dithiocar Vulcanization accelerators such as pamates and xanthates, vulcanization accelerators such as metal oxides and fatty acids, amines / aldehydes, amines / ketones, amines, phenols, imidazoles, sulfur-containing compounds Phosphorus anti-aging agents, naphthenic and aromatic process oils Etc. can be adjusted to effect blended within a range that does not impair the composition of the present invention.

[Effect of the present invention] The rubber composition for a cap tread of the present invention has a high Mooney viscosity, a small Mooney viscosity ML _{1 + 4} (100 ° C), and excellent workability and fluidity, so that the mold has a complicated structure. It easily flows to every corner of the tread pattern and has good moldability. Further, it has good wet skid resistance and wear resistance, and can be used for cap treads of passenger cars, buses, trucks, airplanes and the like in place of conventionally known compositions to produce tires with good wet road surface grasping and good wear resistance.

[Examples of the Present Invention] Examples and comparative examples are shown below. In the following examples, parts mean parts by weight.

The Mooney viscosity ML _{1 + 4} (100 ° C) of the rubber composition is JI
According to SK6300, the tensile modulus of vulcanizate is JIS
Picowear was measured according to ASTM D2228 according to K6301. The wet skid resistance was measured by using a portable skid tester and a safety walk (Type B) manufactured by Three M Company.

In addition, the composition (blending ratio) of the reinforced rubber composition in the following Examples 1 to 14 and Comparative Example 1, the composition (blending ratio) of the cap tread rubber composition of the present invention, and the rubber composition for a cap tread of the present invention. The physical properties and the like are collectively shown in Tables 1 and 2 below.

Example 1 In a Brabender blast graph set at 220 ° C. and 50 rpm, a natural rubber (N having a viscosity of 1 × 10 ⁶ poise (N
R) 100 parts, and N- (3-methacryloyloxy-2-hydroxypropyl) -N'-phenyl-P-phenylenediamine [trade name Nocrac G as an antioxidant.
1, Ouchi Shinko Chemical Industry Co., Ltd.] 1.0 part was added, and after kneading these for 30 seconds, nylon 6 (trade name 1030
B, Ube Industries, Ltd., melting point 221 ° C, molecular weight 30,000
0) 2 parts by weight of 100 parts by weight of N-β (aminoethyl) γ-aminopropyltrimethoxysilane (trade name K
BM603, manufactured by Shin-Etsu Chemical Co., Ltd., hereinafter referred to as Silane A) was charged with 51 parts of pellets which were kneaded in advance and kneaded for 13 minutes (while the temperature in the Brabender increased to 230 ° C.) to obtain a kneaded product. . The obtained kneaded product was cord-shaped at a die set temperature of 235 ° C. using a 20 mmφ extruder (manufactured by Haake) having a circular die having an inner diameter of the nozzle of 2 mm and a ratio of the length of the nozzle to the inner diameter (L / D) of 2. Then, the extrudate was wound on a bobbin at a draft ratio of 10 (speed of 38.8 m / min) through a guide roll installed 3 m below the nozzle. Approximately 500 rolls are bundled into a sheet shape (thickness of about 2
mm, width about 150 mm), and this sheet-like material is rolled about 10 times with a pair of rolling rolls having a roll gap of 0.2 mm and a temperature of 60 ° C. to obtain a reinforced rubber composition (master patch).
(Sample 1) was obtained.

Next, with a Banbury set at 90 ° C. and 77 rpm, the compounding ingredients shown in Table 2 except the vulcanization accelerator and sulfur were kneaded to obtain a kneaded product, and then 10 The vulcanization accelerator and sulfur were kneaded on an inch roll, rolled out into a sheet, and placed in a mold for vulcanization to obtain a vulcanized product. Vulcanization was performed at 145 ° C. for 40 minutes.

Example 2 Instead of silane A, vinyltris (β-methoxyethoxy) silane (trade name: KBC1003, Shin-Etsu Chemical Co., Ltd.)
Manufactured, silane B) was used to obtain a reinforced rubber composition (Sample 2) in the same manner as in Example 1, and the use 2 was used as a reinforced rubber composition in the same manner as in Example 1 except that the cap tread was used. A rubber composition for use was obtained.

Example 3 γ-methacryloxypropyltrimethoxysilane (trade name KBM503, Shin-Etsu Chemical Co., Ltd.) in place of silane A
Manufactured, silane C) was used in the same manner as in Example 1 to obtain a reinforced rubber composition (Sample 3). This sample 3 was used as the reinforced rubber composition in the same manner as in Example 1 except that the cap tread was used. A rubber composition for use was obtained.

Example 4 A reinforced rubber composition (Sample 4) was obtained in the same manner as in Example 1 except that γ-mercaptopropyltrimethoxysilane (trade name KBM803, Shin-Etsu Chemical Co., Ltd., Silane D) was used instead of silane A. A rubber composition for a cap tread was obtained in the same manner as in Example 1 except that this sample 4 was used as a reinforced rubber composition.

Example 5 Instead of silane A, β- (3.4-epoxycyclohexyl) ethyltrimethoxysilane (trade name KBM303,
Example 1 except that Silane E) manufactured by Shin-Etsu Chemical Co., Ltd. was used.
A reinforced rubber composition (Sample 5) was obtained in the same manner as in 1. and a rubber composition for a cap tread was obtained in the same manner as in Example 1 except that this Sample 5 was used as a reinforced rubber composition.

Example 6 Nylon 6 (trade name 1013B, Ube Industries, Ltd., melting point 221 ° C., molecular weight 13,000) 4 parts by weight per 100 parts by weight of silane A 52 parts of pellets kneaded in advance were used. A reinforced rubber composition (Sample 6) was obtained in the same manner as in Example 1, and a rubber composition for a cap tread was obtained in the same manner as in Example 1 except that this Sample 6 was used as a reinforced rubber composition.

Example 7 A reinforced rubber composition (Sample 7) was prepared in the same manner as in Example 1 except that the amount of 6-nylon added to natural rubber was changed to 100 parts.
A rubber composition for a cap tread was obtained in the same manner as in Example 1 except that Sample 7 was used as a reinforced rubber composition.

Example 8 A reinforced rubber composition (Sample 8) was obtained in the same manner as in Example 1 except that the amount of 6-nylon added to natural rubber was changed to 20 parts, and this Sample 8 was used as the reinforced rubber composition. A rubber composition for a cap tread was obtained in the same manner as in Example 1 except for the above.

Examples 9 to 11 Rubber compositions for cap treads were obtained in the same manner as in Example 1 except that the composition (blending ratio) of each component was changed as shown in Table 2.

Examples 12 to 14 Example 1 except that the type of carbon black blended was changed.
A rubber composition for a cap tread was obtained in the same manner as.

Comparative Example 1 A rubber composition for a cap tread was obtained in the same manner as in Example 1 except that the use ratio (composition) of each component was changed as shown in Table 2 without using the reinforced rubber composition.

The amount of bound rubber in each of Samples 1 to 8 (reinforced rubber composition) shown in Table 1 was measured as follows.

[Measurement of bound rubber amount]

2 g of the reinforced rubber composition is added to 200 ml of toluene respectively.
Add at 0 ° C to dissolve the rubber component in the reinforced rubber composition,
The resulting slurry was centrifuged at room temperature to separate a solution portion and a precipitation portion. The above operation was repeated 7 times for the precipitated portion, and then the precipitated portion was dried to obtain a nylon fiber. This nylon fiber was dissolved in a mixed solvent of phenol and orthodichlorobenzene and analyzed by ¹ H nuclear magnetic resonance spectrum (NMR) (internal standard tetramethylsilane). From the NMR chart, methyl groups and methylene groups derived from rubber were analyzed. , A methylene group adjacent to a CO group, a methylene group adjacent to an NH group, and other 3 groups derived from 6-nylon
For each peak of each methylene group, the amount of bound rubber was calculated by obtaining the molar ratio of 6-nylon and natural rubber by the cut area method. The shape of the nylon fiber was measured for about 200 fibers using a scanning microscope at a magnification of 10,000 times. The fibers were very fine short fibers with a circular cross section.

Further, (Note 1) to (Note 4) in Table 2 are as follows.

(Note 1) BR: polybutadiene (UBEPOL-BR1
53A, manufactured by Ube Industries Ltd. (Note 2) N-110: SAF, particle size 18 mμ, DBP oil absorption amount 115 ml / 100 g N-220: ISAF, particle size 21 mμ, DBP oil absorption amount 117 ml / 100 g N-330: HAF , Particle size 30mμ, DBP oil absorption 110ml / 100g N-440: FF, particle size 38mμ, DBP oil absorption 75ml / 100
g N-550: FEF, particle size 41mμ, DBP oil absorption 122ml / 100g (Note 3) Other compounding agents Zinc white 3 parts, stearic acid 2 parts, anti-aging agent N-phenyl-N'-isopropyl-P-
Phenylenediamine 1 part Vulcanization accelerator N-oxydiethylenebenzothiazyl-2
-Sulfenamide 0.8 parts Sulfur 1.7 parts

Claims (1)

[Claims] 1. A fine vulcanizable polyamide short fiber is embedded in a vulcanizable rubber, and at the interface of the fiber, the polyamide and the vulcanizable rubber interpose a silane coupling agent. A rubber composition obtained by blending a reinforced rubber composition (A), a diene rubber (B), and a carbon black (C) that are bonded together and satisfy the following conditions (I) to (IV): A passenger car tire characterized by being used for a cap tread portion. (I) The amount of the polyamide is 1 to 15 parts by weight based on 100 parts by weight of all rubber components, and (II) the ratio of natural rubber and / or polyisoprene in the components (A) and (B) is all. 5-40 for rubber component
%, (III) the amount of carbon black is 60 to 90 parts by weight based on 100 parts by weight of the total rubber component, and (IV) the 300% modulus of the vulcanizate of the rubber composition is 100 Kg / cm ^2. That is all.