JPS63128037A - Passenger car tire - Google Patents

Abstract

PURPOSE:To obtain the titled tire outstanding in moldability, high-speed running and wet road grip capabilities and wear resistance, by using in the cap tread section a specific reinforced rubber composition with low Mooney viscosity and good processability despite high elastic modulus. CONSTITUTION:The objective tire can be obtained by using in the cap tread section a rubber composition (pref. with a 300% modulus of the cured product therefrom >=100kg/cm<2>) prepared by incorporating (A) a reinforced rubber composition in which 1-15pts.wt. based on 100pts.wt. of the whole rubber component, of fine short fibers of polyamide capable of fiber formation is embedded in a curable rubber matrix (pref. of natural rubber), with said fibers bonded to the matrix through silane coupling agent with (B) a diene rubber and (C) carbon black. The amount of the natural rubber and/or polyisoprene rubber in the components A plus B is such as to be 5-40wt% based on the whole rubber component; the amount of the component C being 60-90pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a high elastic modulus and a high Mooney viscosity (ML).
is small and has excellent workability. The present invention relates to a passenger car tire in which a rubber composition is used for the cap tread rubber.

[Industrial Application Fields] Tires are generally required to have excellent maneuverability, durability, etc., and in particular, from the viewpoint of safety, they are required to have excellent wet skid resistance on wet road surfaces.

In addition, based on the recent social demand for resource conservation, research and development is being conducted on tires with low rolling resistance, that is, tires with low energy loss, in order to reduce dynamic loss in tires. The energy loss consumed in a free-rotating tire varies depending on the 4H1 of the tire, etc., but about the entire energy loss is consumed in the tread. Therefore, if the internal consumption of tread rubber is reduced, the energy loss during tire rolling is reduced, and a tire with low rolling resistance can be obtained.

Therefore, attempts have been made to modify tread rubber to reduce energy loss. However, such rubber modification tends to reduce wet skid resistance.

Since improvements in rolling resistance and improvements in wet skidding resistance are generally contradictory matters, various improvements have been made to the tire structure in order to achieve both. One of the ways to do this is to make the tread a two-layer structure consisting of a cap tread and a paste tread. That is, the tread is made of two layers: a cap tread with good wet skid resistance and a paste tread with low energy loss, thereby increasing the wet skid resistance of the tire as a whole and reducing energy loss.

In addition to wet skid resistance and abrasion resistance, rubber for cap treads is required to have a high modulus of elasticity for high-speed running properties and a low viscosity that allows it to easily flow to every corner of the complex tread pattern of the mold.

According to the present invention, a rubber composition can be obtained which has a small Mooney viscosity and excellent processability despite the high elastic modulus of the vulcanizate,
This composition can be used for a cap tread to produce a tire with good wet road grip and wear resistance.

[Prior Art] Various methods have been tried in the past to obtain rubber with a high modulus of elasticity. The method of blending a large amount of carbon black is not preferable because the rubber does not come together well during the processing process, the power load increases during kneading and extrusion, and the compound ML increases, making it difficult to mold the tire. The method of blending a large amount of sulfur has disadvantages such as sulfur pluming and increased crosslinking density resulting in faster crack growth. The addition of thermosetting resins is difficult to achieve good dispersion when added in large amounts, as thermosetting resins have low compatibility with commonly used natural rubbers and diene rubbers, and this kneaded dough is difficult to obtain even when unvulcanized. Because it is hard, the load increases during kneading and extrusion, and the workability of tire molding is poor. If short taaa is simply added, the bond between short taaa and rubber is insufficient, resulting in increased creep and reduced fatigue life.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of the prior art, such as low productivity and low abrasion resistance, by blending a special rubber composition with excellent moldability and high-speed molding. For driving performance and wet road surfaces! An object of the present invention is to provide a passenger car tire with good grip and wear resistance.

[Means for Solving the Problems] That is, in the present invention, fine short FalIn of polyamide capable of forming am is embedded in a vulcanizable rubber, and the fibers are vulcanizable with the polyamide at the interface of the w1 fibers. A reinforced rubber composition (A) in which rubber is bonded via a silane coupling agent, a diene rubber (B), and carbon black (C), and the following (I) to (IT The present invention relates to a passenger car tire characterized in that a rubber composition satisfying the following conditions is used in the cap tread portion.

(I) The amount of counterfeit polyamide is 1 to 15 parts by weight based on 100 parts by weight of the total rubber component, and (II) The proportion of natural rubber and/or polyisoprene in component (A) and component CB) is the same as that of the total rubber component. (m) the amount of carbon black is 60 to 90 parts by weight based on 100 parts by weight of the total rubber components; (IT) 300% by weight of the vulcanizate of the rubber composition; % modulus is 100Kg/ct
It is greater than or equal to n'.

The rubber composition for cap tread used in this invention is:
Due to its high elastic modulus, Mooney viscosity MLI and 4 (1
00°C) and excellent workability and flowability, it easily flows to every corner of the complex tread pattern of the mold, and has good wet skid resistance and abrasion resistance.

In this invention, fine short 1Ili fibers of polyamide capable of forming fibers are embedded in vulcanizable rubber, and at the interface of the fibers, the polyamide and vulcanizable rubber are exposed to a silane coupling agent. It is necessary to blend a reinforcing rubber composition in which the FjA male is bonded to the polymer, and by this, it is possible to produce a rubber composition with excellent moldability even though the FjA male is blended with the polymer. It can be used in treads to produce tires that grip wet road surfaces and have good wear resistance.

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

Vulcanizable rubbers used in the reinforced rubber composition constituting the rubber composition for cap treads of the present invention include natural rubber, cis-1,4 polybutadiene, polyisoprene,
Examples include styrene-butadiene copolymer rubber and isoprene-isobutylene copolymer, and among these rubbers, natural rubber is preferred.

Furthermore, the polyamide used in the reinforced rubber composition is
ia fiber forming material, melting point 150-260°C, preferably 190-235°C, nylon 6, nylon 61
0. Nylon 12. Nylon 611, nylon 612,
Examples include nylon 66 and copolymers thereof. The polyamide is not particularly limited as long as it has fiber-forming ability, but if the number average molecular weight is too low, preferably 35,000 or more, preferably a, ooo or more, the fiber-forming ability will be poor and the strength will be low.

The lily fibers used in the reinforced rubber composition of the present invention are fine short fibers of the above-mentioned polyamide, and these short fibers are
It has a form in which molecules are arranged in the direction of the fiber axis, and preferably has an average diameter of 0.05 to 0.81 L, particularly a circular cross section and a minimum fiber length of 1 hi or more.

In addition, the silane coupling agent used in the reinforced rubber composition has the structural formula Y-RISiX3 or Y
A compound represented by -R1S i R2X2 is used.

Here, Y, R1, R2, and X each represent the following groups.

H5-C3H3- R1: ApCnH2nBqCmH2mB□Cj
H21A: C5H4P=0~2 n=o~5 B: O, NHQ=O~2 Rin=0~5 1;O~5 R2: Cn H2n+1 n
=1~4X: Dr Cn H2n Es C
+s H24+1D: O, C look “=
0 to 2n=o to 5 E: Os=1 to 2 ■=1 to 5 Specifically, γ-7 minopropyltrimethoxysilane, γ
-7 Minoprobyltriethoxysilane, N-β (aminoethyl)γ-7 Minoprobyltrimethoxysilane, N
-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-(diethylenetriamino)propyltrimethoxysilane, γ-ureidopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(βmethoxyethoxy) Silane, γ-glycidoxypropylmethyljethoxysilane, γ-glycidoxypropyltrimethoxysilane, β-
(3,4 epoxycyclohexyl)ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, N-phenyl-γ
-aminopropyltriethoxysilane, N-β(N-vinylbenzylaminoethyl)-γ-7minobrobyltrimethoxysilane hydrochloride group, and the like can be suitably used.

In addition, the ratio of vulcanizable rubber to the weight of polyamide fine short mfa embedded in vulcanizable rubber (vulcanizable rubber/polyamide fine short fibers) is
It is preferable that the polyamide forming the short fibers and the vulcanizable rubber are bonded via a silane coupling agent so that the amount is 10 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. Vulcanizable rubber.

5 to 100 parts of polyamide per 100 parts of the vulcanizable rubber, and 1 part of a silane coupling agent of 0.1 to 5.5 mff per 100 parts of the polyamide at a temperature equal to or higher than the melting point of the polyamide. By kneading and extruding the obtained kneaded product at a temperature higher than the melting point of the polyamide,
Alternatively, it may be obtained by stretching the extrudate at a temperature above or below the melting point of the polyamide, as appropriate. Furthermore, it can also be obtained by using these stretching methods in combination.

The rubber composition for cap tread used in this invention is:
It is made by blending the above-mentioned reinforced rubber composition (A), diene rubber (B), and carbon black (C).

As the diene rubber (B), natural rubber, cis-
Examples include 1,4-polyisoprene, cis-1,4 polybutadiene, styrene-butadiene copolymer rubber, and isoprene-isobutylene copolymer.

Carbon black has a particle diameter of 90 m Jl or less, dibutyl phthalate (DBP) oil absorption [70 m Jl/
Those weighing 100 g or more are preferably used.

Examples of carbon black include HAF and FF.

Various carbon blacks such as FEF, GPE, SAF, 15AF, and SRF are used.

(1) The amount of the polyamide (short fibers m) is the total of the rubber components of 1001. It is 1 to 15 parts by weight, preferably 2 to 15 parts by weight, based on the fi part, and the ratio of rubber is the same as that of natural rubber or polyisoprene in component (A).
The total amount of component B) is 5 to 40% by weight, (m) the amount of carbon black is 60 to 9017 parts per 100 parts by weight of the rubber component, and (IV) vulcanization of the composition. The material is blended to satisfy the condition that the 300% modulus of elasticity is greater than or equal to loOKg/cm'' as specified in JIS K6301.If the amount of carbon black is less than the lower limit, the modulus of elasticity of the vulcanizate decreases. On the other hand, if the amount exceeds the upper limit, the Mooney viscosity becomes too large and tire moldability tends to deteriorate.Also.

If the proportion of rubber is outside the above range, the pico abrasion and wet skid resistance of the vulcanizate will be reduced.

The rubber composition used in this invention is prepared by mixing each of the above-mentioned components in a mixer such as a Banbury mixer or a roll extruder to give a
It can be obtained by kneading at 80°C for about 1 to 60 minutes. Additives such as a vulcanizing agent are blended into this rubber composition.

As the vulcanizing agent, known vulcanizing agents 1 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, and any known blending method can be employed. Along with the vulcanizing agent, white carbon, activated calcium carbonate, ultrafine magnesium silicate, high styrene resin,
Coumarone indene resin, phenolic resin, lignin.

Modified melamine resin, reinforcing agents such as petroleum resin, various grades of calcium carbonate, basic magnesium carbonate, clay,
Fillers such as zinc white, diatomaceous earth, recycled rubber, powdered rubber, ebonite powder, aldehydes, ammonias, aldehyde-amines, guanidines, thioureas, thiazoles, thiurams, dithiocarbamates, xanthates, etc. Vulcanization accelerators, metal oxides, vulcanization accelerators such as fatty acids, amines/aldehydes, amine ketones, amines, phenols, imidazoles, sulfur-containing or sulfur-containing anti-aging agents, naphthenes The composition can be adjusted by blending aromatic or aromatic process oils within a range that does not impair the effects of the present invention.

[Effects of the present invention] The rubber composition for cap tread of the present invention is as follows.

Despite having a high elastic modulus, Mooney viscosity M L 1 +4
(100℃) is small and has excellent processability and fluidity, so it easily flows to every corner of the complex tread pattern of the mold and has good moldability.It also has good wet skid resistance and abrasion resistance, and has a Instead of a composition, it can be used for cap treads for passenger cars, passes, trucks, airplanes, etc. to produce tires with good wet road grip and wear resistance.

[Examples of the present invention] Examples and comparative examples are shown below. In each of the following, parts mean parts by weight.

The Mooney viscosity ML1.4 (100°C) of the rubber composition is J
According to IS K6300, the tensile modulus of the vulcanizate is JI
According to S K2SO3, pico wear is ASTM D222
Measured according to 8. Wet skid resistance was tested using a portable skid tester.

Measurement was performed using ThreeM's Safety Walk (Type B).

The compositions (blending ratios) of the reinforced rubber compositions in Examples 1 to 14 and Comparative Example 1 below are 0, Group J & (blending ratio) of the cap tread rubber compositions of the present invention, and the rubber compositions for cap treads of the present invention. Regarding the physical properties etc., please refer to Part 1 below.
They are summarized in Table and Table 2.

Example 1 100 parts of natural rubber (NR) having a viscosity of txto'boys and N-(3
-methacryloyloxy-2-hydroxypropyl)
-N'-2P-phenylenediamine (trade name: Tsukrak G-1, manufactured by Ohmukai Shinko Chemical Industry ■) was added, and after mixing these for 30 seconds, nylon 6 (trade name: 1030B, manufactured by Ube Industries, Ltd.) was added. Made in ■, melting point 221”0, molecule m3
0.000) 2 parts by weight per 100gl of N-β(aminoethyl)γ-aminopropyltrimethoxysilane (
Product name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd., hereinafter referred to as Silane A
) was mixed in with 51 parts of beret, and 1
Knead for 3 minutes.During this time, the temperature inside the Brabender is 230℃.
), a crosstalk was obtained. The obtained kneaded material was passed through the nozzle 1, ) inner diameter. 11.7e7. ,)□Yon! ,=o ratio.

/D) is a 20mmφ extruder with 2 circular dies (Ha
The extrudate was extruded into a string at a set temperature of 235°C using a 235° C.
/min). Approximately 500 of these rolls were bundled into a sheet (thickness: approximately 21 mm, width: approximately 150 am), and this sheet was rolled to approximately 10 times its size using a pair of rolling rolls with a roll gap of 0.2 mm and a temperature of 60°C. It was rolled to obtain a reinforced rubber composition (masterbatch) (Sample Manufacturing Co., Ltd.).

Next, 90°C, 77 r, P, 11. Using a Banbury machine set at After kneading sulfur and rolling it out into a sheet, it was placed in a mold and vulcanized to obtain a vulcanized product. Vulcanization was performed at 145° C. for 40 minutes.

Example 2 Vinyltris(β-methoxyethoxy)silane [trade name KBC1003, manufactured by Shin-Etsu Chemical Co., Ltd.] was used instead of Silane A.
A reinforced rubber composition (sample 2) was obtained in the same manner as in Example 1, except that Silane B) was used, and a capped rubber composition (sample 2) was obtained in the same manner as in Example 1, except that Use 2 was used as the reinforced rubber composition.
A rubber composition for /-/ was obtained.

Example 3 Instead of Silane A, γ-methacryloxypropyltrimethoxysilane (trade name KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.,
A reinforced rubber composition (sample 3) was obtained in the same manner as in Example 1, except that silane C) was used, and a rubber for cap tread was obtained in the same manner as in Example 1, except that this sample 3 was used as the reinforced rubber composition. A composition was obtained.

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

Example 5 β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (trade name KBM303,
A reinforced rubber composition (Sample 5) was obtained in the same manner as in Example 1 except that Silane E) manufactured by Shin-Etsu Chemical Co., Ltd. was used.
A rubber composition for a cap tread was obtained in the same manner as in Example 1, except that the following was used as the reinforced rubber composition.

Example 6 Nylon 6 (trade name: IOL 313, manufactured by Ube Industries, Ltd.).

A reinforced rubber composition (Sample 6) was prepared in the same manner as in Example 1, except that 52 parts of pellets in which 4 parts by weight of Silane A were pre-mixed per 100 parts by weight (melting point 221"0, molecular weight 13,000) were used. A rubber composition for a cap tread was obtained in the same manner as in Example 1, except that 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 the 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 the natural rubber was changed to 20 parts, and this Sample 8 was used as a reinforced rubber composition. Otherwise, a rubber composition for a cap tread was obtained in the same manner as in Example 1.

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 to be blended was changed
A goto composition for cap tread was obtained in the same manner as above.

Comparative Example 1 A rubber composition for a cap tread was obtained in the same manner as in Example 1, except that the reinforcing rubber composition was not used and the proportions (composition) of each component were changed as shown in Table 2.

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

[Measurement of bonded rubber amount]

2 g of each reinforced rubber composition was added to 200 mJL of toluene at 80° C. to dissolve the rubber component in each reinforced rubber composition, and the resulting slurry was centrifuged at room temperature to separate into a solution portion and a precipitated portion. After repeating the above operation seven times for the precipitated portion.

The precipitated portion was dried to obtain nylon fibers. This nylon m-fiber was dissolved in a mixed solvent of phenol and orthodichlorobenzene, and 1H nuclear magnetic resonance spectrum (NMR) was obtained.
Analysis (internal standard tetramethylsilane) L, NMR chart shows methyl groups and methylene groups originating from rubber, 6-
Methylene group adjacent to CO group originating from nylon, NH
For each peak of the methylene group adjacent to the group and the other three methylene groups, the molar ratio of 6-nylon to natural rubber was determined by the cut area method, and the amount of bonded rubber was calculated. In addition, the shape of the nylon fibers is approximately 20 mm.
Measurements were made using a Scan 1J1 microscope at a magnification of 10.000x. am was an extremely thin short fiber with a circular cross section.

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

(Note 1) BR: Polybutadiene (UBEPOL-BR153A.

(Made by Ube Industries) (Note 2) N-110: SAF, particle size 18 mp, DBP oil absorption Jil 15 ml/100 g N-220: 15 AF,
n 21mp, // 117mQ/100gN-
330: HAF, tt 30rnIL, n
! 10m1/LOOgN-440:FF, n
38rng, n 75mA/100gN-550
:FEF, n 41mIL, // L22m
Q/100g (Note 3) 3 parts of other compounding agents zinc white.

2 parts stearic acid.

Antiaging agent N-phenyl-No-isopropyl-P-
Phenylenediamine 1 part Vulcanization accelerator N-oxydiethylenebenzothiazyl-2
- Sulfenamide 0.8 parts Sulfur 1.7 parts

Claims (1)

[Claims] Fine short fibers of polyamide capable of forming fibers are embedded in vulcanizable rubber, and at the interface of the fibers, the polyamide and vulcanizable rubber absorb a silane coupling agent. A rubber composition comprising a reinforced rubber composition (A), a diene rubber (B), and carbon black (C) that are bonded through a rubber composition, and which satisfies the following conditions (I) to (IV): A passenger car tire characterized in that a cap tread 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 the total rubber components, and (II) The proportion of natural rubber and/or polyisoprene in components (A) and (B) is 1 to 15 parts by weight. 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 components; (IV) the 300% modulus of the vulcanizate of the rubber composition is 100 Kg/cm^ It is 2 or more.