JPS5949247A - Rubber composition for tire tread - Google Patents

Abstract

PURPOSE:To obtain titled composition capable of giving racing tires with high strength and wear resistance and large energy loss at the contact road surface, by using a master batch prepared by blending, in a wet process, a rubber component with specific ultrafine carbon black, etc. CONSTITUTION:A coagulant is added to a master batch consisting of (A) 100pts.wt. on a solid basis, of a rubber latex containing >=70wt% of diene rubber component, (B) 80-15pts.wt. on a solid basis of a slurry prepared by dispersing in water a carbon black with a nitorgen adsorptive specific surface area of 120-200m<2>/g, and (C) 70-110pts.wt. of an aromatic process oil and/or high viscosity oil to effect coagulation. Subsequently, 100pts.wt. of the rubber component in the dried solid from the above coagulated product is incorporated with 5-30pts.wt. of the carbon black mentioned above and 0-30pts.wt. of the ingredient (C), thus obtaining the objective composition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rubber composition for a tire tread, particularly a rubber composition suitable for a tread for a racing tire. More specifically, the present invention relates to a tire composition suitable for treads for racing tires, which has excellent durability and is obtained by using a wet process carbon black masterbatch.

When obtaining a rubber composition, carphone black (
(hereinafter simply referred to as OB) is added or mixed in order to increase the hardness, tensile strength, and tear or peel strength of the final product. When adding CB to a rubber material, fine particles of OB must be uniformly dispersed and mixed into the rubber material. To perform such mixing, conventionally, CB is mixed with the rubber and other ingredients in a Banbury mixer, or OB is added and kneaded with the other ingredients to the rubber being kneaded on a roll mill. These mixing methods are usually called dry mix methods, and are currently the most widely used method for blending and dispersing OB in the rubber industry.

By using the 1 Ni Drymix method, ordinary OB is well dispersed at a practical level and is widely used as a rubber composition for general purposes.

On the other hand, when changing the OB to be added from the generally used particle size range to a significantly smaller particle size,
In particular, ultrafine particles of CB (i.e., those with an increased specific surface area indicated by the amount of nitrogen adsorbed), specifically N-1to (N-ti□ is called in ASTM as a grade of OB) The name is N −/1
0 is the specific surface area/Jsm"/j?) When it comes to OBs with fine particle diameters near or larger, it is not easy to reach a practical level of OB dispersion using the normal dry mix method. That is, in general, the nitrogen adsorption specific surface area (8N2,
As the IK (hereinafter referred to as BN2) increases, the tensile strength increases
B (hereinafter referred to as TB) increases, but the degree of dispersion of OB begins to decrease rapidly. Then, TB stops rising from around 5N2==/λθ, and when SN2 exceeds lkoO, it reverses to r
B shows a tendency to decrease, and in this case, it requires human power dedicated to energy that exceeds the kneading energy 1 that is usually considered. To avoid this, a slight improvement can be made by increasing the kneading process into multiple stages, but the fundamental This is not a practical solution.

- In the case of racing tire treads, due to the special performance requirements, so-called styrene-butadiene rubber (SBR) has a bonded styrene stitch of 3θ or more.
) and OB with a small particle size are often used. Normally, as the kneading of SBR progresses, the viscosity of SBR decreases due to temperature rise or molecular cutting.

High styrene SDR is standard 8BR (bonded styrene Jj
i, 23. When using CB whose dispersion is j1b in the presence of stress, the viscosity decreases rapidly due to kneading compared to the
Part B (sexuality will be significantly reduced).

In addition to the above-mentioned problems, racing tire treads require small particle diameters of O and B that are unimaginable for tire treads of Jt 1 and above in order to improve their marginal performance. Furthermore, the bad conditions will turn into cars.

In the 11 temples and 4 cities of Lage/Getaia, it is difficult to disperse with the normal dry mix method, that is, EIN2.
ga/i-o m7. ! Ultrafine particle OB of 7 or more and 5.2 o o nV9 is often used, and in this case the kneading is +jB? 1'l requires great care and a great deal of kneading.

As mentioned above, it is a difficult time! In the dry mix method, which is economically disadvantageous due to M The dispersion degree was only a few inches lower, and it can be seen how the OB dispersion becomes a limiting factor in improving the performance of the rubber composition.

In addition, one of the basic physical properties required for racing tires is energy loss or hysteresis loss between the tire tread and the road surface, which affects the stability and maneuverability of the car equipped with the tire. , stability is improved. And the given rubber species, carbon black god,
In order to minimize the energy loss mentioned above in addition of carbon black, carbon black, and addition of oil (aromatic process oil), it is sufficient to maximize the interaction between OB and rubber. In the mix method, S
When blending OB with N2: / J, o -zg or more, (poor dispersion of 3B, that is, agglomeration of 0'B, tends to occur, so it is necessary to effectively use CB with a high SN2 value as described above. I can't.

Under the above-mentioned background, the inventors have developed the above-mentioned rough
(Several σ) There are many inconvenient problems, and it is also unsatisfactory in terms of efficiency... We have conducted various studies to find a rational OB dispersion method instead of the dry mix method of istyrene SDR and ultrafine particle CB. The present invention has achieved C"-. That is, the present invention satisfies the requirements for tire treads, especially racing tire treads. 1 is well dispersed and blended to maintain strength, 1tlP↓' wear and tear, and when used as a tire]-sa (improves energy loss between the ground and the heat surface) The purpose is to provide a rubber composition effective for use in racing tire treads, the gist of which is (a) 7.
Rubber latex containing a diene type component of 0-Ba ■Measurement weight (b) Carbon black with a nitrogen adsorption area of 1.20 to 200 g Solid content of carbon black slurry obtained by dispersing it in water is 0 to 0 parts by weight, and (C) aromatic process oil and/or high viscosity oil 7
A tire obtained by adding a coagulant to a mixture obtained by mixing O-I10N, and blending it with ~30 parts by weight of counterfeit black and ~30 parts by weight of aromatic process oil and/or high viscosity oil. Existing in rubber for treads.

The present invention will be explained in detail below.

In the method of the present invention, the diene thread rubber latex is /, 3
= A conventionally known method in which butane diene St form or/and 3-butadiene monomer and styrene monomer are emulsified and dispersed in an aqueous medium using an emulsifier, and a polymerization reaction is caused by adding a polymerization initiator. Manufactured by:

As the emulsifier used, anionic surfactants such as fatty heavy soap, rosin heavy soap, naphthalene sylephonate sodium formalin butyrate, and sodium alkylbenzenesulfonate are usually used.

Redox initiators are used in Gold Rubber formulations, which polymerize at 0-20°C. Redox I;・Combination of saturated peroxides such as idrovermexite, barometasonoid 1,1 veroxitide and sulfuric acid 'l'E-chichi.・
In general, sulfogyralates and the like are used as main agents.

Alternatively, if you want to obtain emulsified polybutadigone (EBR) latex using only 3-butadiene, add nitroben-vinyl 11j a, r-based W addition 1a, can also be done)
.

, :l0 When the usual emulsion IIi:i &' (two times polybutadiene comb or styrene-butadiene rubber) is introduced, when the polymerization reaction rate reaches tS -1,A%I/i- [If the 111 reaction rate is 6S% or more, branching (': + fractional acid component) will occur in the polymer main chain, and the processability of the raw material will be significantly reduced.] The polymerization reaction is stopped by adding a polymerization termination + E agent such as carbamate or diethyl hydroxylamine.Unreacted monomers are stripped off using steam or the like, and the polybutadiene rubber latex is
I can do 1 toro.

The rubber latex used in the method of the present invention is a diene-based rubber J
It contains 70% by weight or more (proportion as solid content) of 1 component, and if it is less than this amount, the dispersibility of CB is poor and IL 1. 'N wear resistance is reduced. Other than diene rubber components, natural rubber, ethylene-propylene rubber 1. Also, rubber latexes containing diene rubber components include SBR, especially EIBR radex of istyrene, and polybutadiene rubber (F
jilR) Use of latex [SBR/BBR=tro
/, 2o-2o/Io (solid content ratio)], the il abrasion resistance can be improved.

In the rubber latex obtained as described above, the superimitation particles OB, i.e., SN2/, 20-200 gou of CB [the latter ♂O to iro parts by weight per 100M parts of solid content of the former (by weight)
Aromatic process oil and/or high viscosity oil (70 to 10 parts by weight based on 10 parts by weight of rubber slate) which are commonly used to improve the ratio of solid content] and the processability of rubber are mixed. Make a CB rubber latex masterbatch. In this case, the OB to be mixed is an aqueous dispersion (slurry)
Add to rubber latte in the form of As the aqueous dispersion of CB, it is preferable to use a so-called super dispersion method in which OB is added to water and stirred at high speed to obtain an OB slurry. In other words, the finger pressure is weak (・and the water is not compatible with the CB.There is a problem with this. Regarding this super dispersion, for example, see Yoneyama Patent No. 2, 71.'
17ri! It is preferable to carry out the method described in No. 4).

As described above, the rubber latex and CB slurry batch are coagulated with an acid such as sulfuric acid, and then subjected to water washing, filtration, and drying, and then subjected to a carbon black masterbatch (hereinafter abbreviated as W-OBMB) using a wet method. obtain).

For W-OBMB thus obtained, OBj ~ 30 parts by weight (100 parts by weight of the rubber component)
The CB used in this case is not particularly limited, but has a nitrogen adsorption specific surface area of 7.20 to 200? It is even better if CB of 9 is used) and aromatic process oil and/or high viscosity oil θ ~ 30 heavy forged parts, and if necessary,
Compounding agents commonly used in this field are added, kneaded in a Banbury mixer, and vulcanized in a conventional manner.

In the composition of the present invention, W-C! In the preparation of BMB and the final composition therefrom, the Nocom component, O
The blending ratios of the B acid component and oil components such as process oil were specified for the following reasons. In other words, automobile tires must have a good balance of functions such as performance, ride comfort, and stability when running, and rubber compositions for tires each have a role to play, and each By changing the amount of additive, a slight difference will be made in the balance of tire performance.For example, increasing the CB stitch will make the tire harder and make the ride of the car worse.
Increasing the tire will make the tire softer and the ride will be more comfortable. However, if the oil is added too much, the wear resistance will be extremely reduced. Furthermore, as the amount of sulfur increases, the tires become harder and ride comfort decreases. Taking these various factors into consideration, in the present invention, the proportions of each compounded component were determined so as to obtain a tire tread rubber composition suitable for racing use.

As described above, according to the present invention, ultrafine particles, that is, OB with a large specific surface area, are used and mixed with rubber components and other compounding components to create a masterbatch by a wet method, compared to the conventional dry mix method. 1. Achieves good OB dispersion with a small number of steps and low kneading energy, and has excellent properties such as wear resistance and blowout characteristics, and when made into a tire, it has a good OB dispersion rate and a low kneading energy. It is possible to obtain a rubber composition suitable for a racing tire tread, which has a large energy loss and provides stable maneuverability.

Next, Examples and Comparative Examples of the present invention will be shown.

Example 1 / 3-Butadiene monomer and styrene monomer were emulsified and dispersed in an aqueous medium using a mixed emulsifier of fatty heavy soap and rosin heavy soap, and a polymerization initiator was used as hafmethane. It is a combination of hydroperoxide and ferrous sulfate, and sodium formaldehyde sipoxylate is used as a reducing agent.

Polymerization was carried out at temperatures below °C. This SBR with a bound styrene content μO% was collected.

700 parts by weight of aromatic process oil and carbon black, 'N//0 [SN2
73 n1 dibuti cephthalate (hereinafter abbreviated as DBP) oil absorption iiAml/loog]ioo parts by weight were dispersed into 71< by ultra-dispersion method (according to the method described in the specification of U.S. Patent No. Schiff 6z7rij) to obtain OB. Add the slurry, mix well at SO~70℃, coagulate with sulfuric acid, wash with water at ℃・, filter,
Dry at θ°C.

The thus obtained W-OBM B, [, this W'-CBM: B was mixed with ioo parts by weight of the rubber component in B, and was mixed into a 00C type Banbury mixer [circulating water humidity 70°C, rotor rotation speed jμ , j (front)/lQ, t (rear) rpm
] and mixed the mixed compound at 70 inches (,2t,
μcnt) Cooled with a roll and made into a sheet.

The rubber 7 to 7 thus obtained was added with sulfur, 73 heavy parts and a vulcanization accelerator (Sancera NOB, manufactured by Mikumi Kagaku Co., Ltd.).
Add the active ingredient N-oxydiethylene-nopenzothiazyllebenamide)
The mixture is kneaded using an OOC type panburi mixer, and then the kneaded product is cooled using a 70-inch roll and formed into a sheet. This rubber sheet was molded and vulcanized using a super press at 133° C. for 30 minutes. The physical properties of this product are shown in Table 7 below.

Example λ SN2 is /17q as OB, 9. DBP oil absorber is 1
．． A rubber composition was obtained in the same manner as in Example 1 except that 22 ml//00 g of ultrafine particles CB was used. The physical properties of this product are shown in Table 2.

Comparison 1teri This is based on the conventional dry mix method.

/, high styrene 8B from 3-butadiene and styrene
The procedure was the same as in Example 1 until the R latex was obtained.
To BR latex, 37. , 1 part of tMrf is mixed at 0~70°C, coagulated with sulfuric acid, washed with water, filtered, and dried at 20°C.

The process oil-containing SBH obtained in this way was treated with the 100M rubber component as a reference.
J j 5' (SN2 is I I rtVj?,
DB “Beat Yuden・/j J me//00,!
9)' / (7-fold flower and aromatic process oil A
2. jM: Divide and blend parts as follows. That is, the final total weight is OB//Q, weight 14 parts, process oil/'
Make sure that there are 00 double characters.

First, process oil Kanyu 8BH, its rubber component y 00
, j[j divided by j to H = part, /7.2 of the total formulation i of 043 and process oil [it and stearic acid /, O weight h1 part and rβ zinc oxide 3.0 relay part OO
A-type Panbarimigiza? Rz building, and this product is cooled with a 10-inch roll and made into a sheet.

With this 1 ton of nitrogen, the remaining OB
I, H and process oil were mixed in the same way using an O O type Banbury mixer (4 L), and this mixture was cooled and sorted using an I/O inch roll.

This sort and Ikuya/, 73 circumstances department and vulcanization accelerator (Sunseller N0B)), 0 accounting department are 000
The mixture was kneaded using a JrlIj Banbury mixer, and the kneaded product was cooled using a 10-inch roll and formed into a sheet.

Next, mold this rubber sheet, use a heat press, izs
Vulcanization was carried out at 1.20 minutes. The physical properties of this product are shown in Table 7.

Comparative Example This example uses the wet mix method to prepare w-cBbtn, as in Example 1, but for comparison as OB (Fll
The same SN 2 used in / is O of r g , , yg
B (N 3-?) is used (・, all others are real hf)
The same procedure as in Example 1 was carried out. Table 1 shows the physical properties of the rubber composition.

Comparative Example 3 In this example, like Comparative Example 1, O
B is mixed, but CB N, 2.20 (E'!N
2 is 10aylyyg, DBP oil absorption M is /, i sm
e//00g) was used, and the rest was carried out in the same manner as in Comparative Example/2. The obtained rubber composition (1) was added to the seventh
1゜ Comparative Example 1 This example is similar to Example 1, and uses the wet mix method to make W-C and BMB, except that OB is used in Comparative Example 3 (same as , SN2 is IO'1rrl). /C of I
B112.20 was used, and everything else was carried out in the same manner as in Example. The physical properties of the obtained rubber composition are shown in Table 1.

Comparative Example j Similar to this Example Comparative Example/, CB was produced by the dry mink method.
711 sum, but as OB used in Example 1 (・
The same procedure as in Comparative Example 1 was used except that SN2 was 13JIH-I and CBIJ/10 was used. Physical properties of J products in the 7th Kayami] ":Zu.

Example 31J for each comparative example t: Comparison [6+1 / Similarly, 1f rows, OB and
Ultrafine particles OB having a particle size of /f 77n''/g were used.The physical properties of the obtained rubber composition are shown in Table 7.

Write down the physical properties and other properties of each rubber composition in t112 above with a brush 1.
As shown in the table, each medium eye in this table was measured by the following method.

The degree of dispersion of OB was measured using a sledge-type microtome (TJeitz
(manufactured by).

The viscoelastic properties were determined using a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho) at a temperature of 23
℃, frequency 1OH2, strain j% mechanical treetop error correct hit! ', (
tan δ) was determined.

The anti-singing elasticity is J Engineering 5K-1,30/, and the Lübke equation (,
Measurements were made using a 1 year old model).

Abrasion resistance is Akron abrasion (BS standard 903 Part A9)
C) and wear and tear (ASTM D, 72.2
1) Both were measured. The former is the Akron abrasion test (1
Yu (-L Island Seisakusho 㔜゛L), the latter is Pico), wear F, A'
,? ;j; Machine [Ferry W Schiff (Ferry Ma
(manufactured by Chine).

Wet skid resistance value (index) was measured using a portable wet skid tester (UK 5tan, Ley Co., Ltd.).
lJ, road surface: Sumitomo 3M Company Safe Day Walk
Taigu B, Mizusawa, 20°C) was used for measurement.

The boot o-out characteristics are determined by the Gutdrich flexometer (
The temperature is 100℃, the stroke is 7.2 mm, the load is 6.2 bond (2, 1',
/ kg), and took 7 minutes (・, The cut cross section was evaluated as follows. In other words, J grade evaluation was performed (・, crack generation is l, small hole formation is 3, hole formation is 4F). ：None is set as j,
Evaluate λ and l as intermediate between it'e h.

Power consumption 5-4 shows the power consumption by operating the 00C type Banbury mixer, and the power consumption in the 7th stage does not include the vulcanizing agent. A compound containing a sulfuric agent that consumes heavy nails.

In the above table, OB is mixed in the form of an aqueous slurry, as in the dry mix method, and wet is in the uninvented method.
From the table, q) The method of mixing with latex shows that the method of mixing with the latex has various physical properties of the resulting composition, consumption during production, and It is clear that %<, 11 (・).

However, the examples listed in the examples are in addition to typical examples for obtaining 3,4i1mN+141J of the present invention, and the non-explosion [! No. 11 is not limited by these examples, and other modifications may be made within the gist of the invention.

337-

Claims (3)

[Claims] (1) (a) Rubber latex containing 70% car sickness% 1s7 diene rubber component as solid content, ioo parts by weight, (b
) I (solid content of carbon black slurry obtained by dispersing carbon black with an elementary adsorption specific surface area of /20-.2007J9 in water, gO ~ /10 parts), and (c) aromatic A coagulant is added to the mixture obtained by mixing 70 to 11 parts of process oil and/or high viscosity oil, and t to 30 parts of carbon black are juxtaposed with aromatic process oil and A rubber composition for tire treads, which is partially blended with 0 to 30 weight M of high viscosity oil and/or high viscosity oil. (2) The diene thread rubber component of the rubber latex is a styrene-butadiene rubber having a bonded styrene/j N60 weight ratio. Rubber composition for tire tread according to LJi (3) The rubber latex contains bound styrene/styrene-butadiene rubber latex with a weight ratio of J-30 and polybutadiene rubber latex (obtained by an emulsion polymerization method). Rubber composition for tire tread according to item 7