JPH1149895A - Production of rubber composition containing modified carbon black for rubber reinforcement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a rubber master batch composition containing surface-treated carbon black for rubber reinforcement, having excellent tanδ temperature dependency inherent in silica, good in abrasion resistance and processability, and free from any problem due to low electrical conductivity. SOLUTION: This rubber composition is obtained by mixing (a) 100 pts.wt., on a solid basis, of a diene-based rubber component latex with (b) 10-250 pts.wt., on a solid basis, of a slurry containing water-dispersed silica and rubber- reinforcing carbon black or (b') 10-250 pts.wt. of modified carbon black prepared by modification granulation through addition of water-dispersed silica, followed by solidifying the mixture with a solidifying agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a rubber masterbatch composition containing a modified carbon black for rubber reinforcement (hereinafter sometimes simply referred to as "modified carbon"), and more particularly to a diene-based rubber composition. The present invention relates to a method for producing a rubber masterbatch composition containing rubber and a modified carbon black for rubber reinforcement having water-dispersed silica adhered to the surface. The rubber composition containing the modified carbon black for rubber reinforcement can be used for various rubber products such as tire conveyor materials such as tire cap treads and side treads, belt conveyors, industrial rubber rolls and hoses.

[0002]

2. Description of the Related Art In the rubber industry such as the tire industry,
Carbon black used for rubber reinforcement is mixed with rubber in advance using a wet carbon black masterbatch method to simplify the process of kneading carbon black into rubber and dispersibility of carbon black in rubber. (See, for example, JP-A-59-49247 and JP-A-63-43937). By the way, in recent years, with the advent of excellent silane coupling agents, silica has been blended in place of carbon black. Silica has a higher temperature (60
Tan δ at low temperature (around 0 ° C).
Since it has a characteristic of high an δ, for example, when used in a rubber composition for a tire tread, there is an advantage that a tire having low rolling resistance and high gripping force can be manufactured.
However, silica is inferior to carbon black in abrasion resistance and has low electric conductivity.For example, when used for tires, the tires are charged during traveling, and noise is generated in electronic devices such as radios. In some cases, there are various problems such as malfunction.

To improve the dispersibility by coating the surface of a pigment or the like with silica or the like or to improve the weather resistance,
For example, Japanese Patent Publication No. 50-14254 and Japanese Patent Publication No. 7-30
No. 269, etc., none of them mention that silica is adhered to the surface of carbon black for rubber reinforcement. Further, JP-A-8-2
JP-A-77347 describes that silica is adhered to the surface of carbon black for rubber reinforcement, but does not refer to efficient industrial production.

[0004] When compounding silica into a rubber composition, dispersion of silica during kneading is difficult to proceed, and a large amount of labor is required for kneading, so that a master batch such as carbon black is desired. However, silica has heretofore not been able to produce a satisfactory wet silica masterbatch because the coagulation pH (about 4 to 7) is different from the coagulation pH range of rubber latex (about 2.5 to 3).

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an excellent tan δ temperature dependency of silica, good abrasion resistance and workability, and no problems caused by low electric conductivity. Another object of the present invention is to provide a method for producing a rubber masterbatch composition of silica-modified carbon black for rubber reinforcement, which can be produced simply and at low cost.

[0006]

According to the present invention, (a)
A mixture of 100 parts by weight (as a solid content) of a latex of a diene rubber component and 10 to 250 parts by weight (as a solid content) of a slurry containing (b) water-dispersed silica and carbon black for rubber reinforcement is coagulated with a coagulant. A method for producing the modified carbon black-containing rubber composition for rubber reinforcement is provided.

According to the present invention, there is also provided a modified carbon black modified and granulated by adding (a) 100 parts by weight of a diene rubber component latex (as solid content) and (b ') water-dispersed silica. Parts by weight and then coagulating the mixture to provide a process for producing a carbon black-containing rubber composition.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the present inventors
By coagulating with a diene rubber latex, a completely new modified rubber black for rubber reinforcement, which has the excellent tan δ temperature dependency of silica and has good abrasion resistance and no problems caused by low electrical conductivity. Succeeded in obtaining a silica-containing rubber master batch composition by a wet method.

The rubber reinforcing carbon black used as a raw material for the production of the silica-modified carbon black for rubber reinforcing used in the present invention includes any carbon conventionally used widely as a rubber reinforcing carbon for tires and the like. Black can be used. Preferred carbon blacks are GPF to SAF grade rubber reinforcing carbon blacks produced by an oil furnace method. Depending on the use of the rubber composition, the carbon blacks can be selectively used or a blend of two or more types can be used.

The modified carbon black for rubber reinforcement according to the present invention can be produced, for example, as follows. That is, the carbon black for rubber reinforcement and the water-dispersed silica are mixed to form a slurry. To improve the dispersibility of carbon black, a suitable dispersant (eg, methanol,
(Various surfactants) may be added. By setting this to, for example, a pH (around 7) in a region where water-dispersed silica particles cannot independently exist, a modified carbon black in which silica adheres around the carbon black can be obtained. The slurry thus obtained is mixed with rubber latex. The amount of silica attached to the surface of the carbon black is not particularly limited, but is preferably 0.1 to 25% by weight based on the weight of the silica-modified carbon black. If the silica adhesion amount is too large, coagulation with the rubber latex tends to be difficult. Further, after adding the water-dispersed silica to the carbon black, the carbon black granulated in the granulating step is slurried by a conventional method, and the resulting mixture is mixed with a latex of a diene rubber component to obtain a mixture.

The rubber latex-modified carbon black slurry mixture of the present invention can also be produced by coagulating the thus obtained rubber latex-modified carbon black slurry mixture by a conventional method. As the coagulant, for example, acids such as sulfuric acid and formic acid, electrolytes such as salt, and general coagulants such as a polymer flocculant can be used (these may be used in combination). It is on the street.

As the water-dispersed silica used in the present invention, those produced by mixing and reacting a metal silicate and an acid according to a conventional method can be used. The form of the water-dispersed silica (whether it may be a sol or a gel) and the concentration of silica in the water-dispersed silica are not particularly limited. The following are appropriate: On the other hand, a commercially available water-dispersed silica can also be used. Commercially available water-dispersed silica is generally produced by the ion-exchange membrane method and contains almost no impurities such as sodium salts as compared with those produced by the above method. It is characterized by its state being maintained, and can be suitably used for producing the rubber composition of the present invention. The preferred diameter of the silica particles is 1 to 100 nm, and the sodium ion content thereof is 1.0% by weight or less in terms of Na ₂ O.

The water-dispersed silica sol is a dispersion of silica primary particles or silica having a low-order structure in water, and is usually stabilized in a basic state. In the present invention, in the production of the treated carbon black, for example, after adjusting to a neutral condition under which the silica sol gels by adding an acid, the mixture is mixed with the carbon black or after mixing the carbon black and the water-dispersed silica, and then added with an acid. The carbon black and silica can be compounded by adjusting the conditions to the properties. In addition, simply mixing water-dispersed silica and carbon black and drying them causes gelation of the silica during the drying process, and also causes complexation with the carbon black (at least a portion of the silica is deposited on the surface of the carbon black). Glue). The step of compounding the carbon black and the silica by the above-described method may be a granulation step or after the carbon black is slurried.

A feature of the present invention resides in that the water-dispersed silica is used as a source of silica for attaching to carbon black. The modified carbon black for rubber reinforcement disclosed by the present inventors in Japanese Patent Application Laid-Open No. 8-277347 is disclosed. It can be manufactured more industrially and efficiently.

According to the present invention, a rubber composition having excellent abrasion resistance, grip performance, rolling resistance and the like can be obtained by blending a modified carbon black for rubber reinforcement with a crosslinkable component such as a diene rubber. . Examples of such crosslinkable rubbers include natural rubber (NR), various butadiene rubbers (BR), various styrene-butadiene copolymer rubbers (SBR), polyisoprene rubber (IR), butyl rubber (IIR), acryloyl Nitrilobutadiene rubber, chloroprene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene copolymer rubber , Chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber,
Fluororubber, urethane rubber, and the like can be used, and these can be used alone or as a blend. When a blend is used, the blend ratio is not particularly limited.

The modified carbon black-containing composition for rubber reinforcement used in the present invention contains 10 to 250 parts by weight, more preferably 15 to 200 parts by weight, of the modified carbon black for rubber reinforcement per 100 parts by weight of the rubber component. If the compounding amount is too small, the modified carbon for rubber reinforcement cannot be compounded in an amount normally required (10 parts or more) when used as various rubber products. Conversely, if the content is too large, the hardness becomes too high, and the workability is lowered.
In the rubber composition, in addition to the water-dispersed silica-modified carbon black, any carbon black and / or silica usually blended in the rubber composition can be used in combination.

In the rubber composition, in addition to the rubber, carbon black having water-dispersed silica adhered to the surface, etc., any compounding agent usually used in the rubber industry, for example, sulfur, organic peroxide, softening agent Agents, anti-aging agents, vulcanization accelerators,
A filler, a plasticizer, a silane coupling agent, and the like can be appropriately compounded as needed within a usual compounding amount range.

The modified carbon black-containing rubber composition for reinforcing rubber of the present invention can be produced by the same method as a usual wet carbon black masterbatch method. A slurry of carbon black having silica adhered to the surface is produced by the method described above, and this is mixed with a diene rubber latex (for example, SBR latex) at an appropriate ratio.
Next, a coagulant (for example, a polymer flocculant, NaCl, etc.) generally used for the production of a carbon black masterbatch or the like is added to these to coagulate.
The coagulated rubber composition is separated from the aqueous phase, and water is removed by, for example, hot-air drying to obtain a target rubber master batch composition. In the above process, additives such as an antioxidant process oil and a silane coupling agent can be added as required.

As described above, the modified carbon black for rubber reinforcement used in the present invention is produced by, for example, adhering water-dispersed silica to the surface of the carbon black in a carbon black slurry. Exist in a state. Therefore, the rubber composition of the present invention can also be produced by directly mixing this slurry with rubber latex. As a result, the labor of kneading silica with rubber can be omitted, and the dispersion of the rubber reinforcing modified carbon black in the rubber is improved, and the rubber reinforcing modified carbon black is recovered from the slurry and dried. The process is skipped, which can further contribute to a reduction in manufacturing costs.

In a preferred embodiment of the present invention, a process oil and / or a synthetic plasticizer such as an aroma oil, a paraffin oil and a naphthene oil which are conventionally generally used for compounding rubber during the wet mixing. 10 to 200 parts by weight of a liquid material such as liquid rubber per 100 parts by weight of diene rubber
Parts by weight can be blended.

[0021]

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples, but it goes without saying that the scope of the present invention is not limited to these Examples.

Examples 1 to 7 and Comparative Examples 1 to 2 Preparation of modified carbon black for rubber reinforcement (for Example 1 ) 100 g of carbon black for rubber reinforcement (N339) was used, and 2 liter of water-dispersed silica was added thereto. A mixed slurry was formed. As water-dispersed silica, sodium hydroxide
JIS No. 1 sodium silicate aqueous solution and a predetermined amount of dilute sulfuric acid for neutralizing the aqueous solution are added to water adjusted to pH 10, and a sol-like water-dispersed silica is finally added in an amount of 0.5% by weight as SiO _2. Obtained.

The water-dispersed silica slurry of carbon black obtained above is heated to 90 ° C., the pH is adjusted to 7, and a slurry-like substance (solid content: 5.2% by weight) containing the desired modified carbon black is added. Obtained.

Preparation of modified carbon black for rubber reinforcement
(Examples 2 to 7) Modified carbon black for rubber reinforcement was produced as follows using commercially available water-dispersed silica (see Table III). Table for non-granulated carbon black (N339)
The commercially available water-dispersed silica shown in III is appropriately diluted with water and mixed so that the silica content is equal to the weight of carbon and each silica content is 1% by weight of the total amount of carbon black and silica. Granulation was performed at about 80 ° C. using a black granulator (barbed screw type). About 105 ° C
To obtain a modified carbon black for rubber reinforcement shown in Table II.

Preparation of Rubber Composition Containing Modified Carbon Black
(Examples 1 to 7) Next, the modified carbon black obtained above was slurried (concentration: 1).
2.5% by weight), 200 g of the mixture and 125 g of SBR1502 latex (concentration: 41% by weight) were mixed, and 1,000 g of saline (concentration: 3% by weight) was added as a coagulant. After stirring for 5 hours, the mixture was dried at 80 ° C. for 24 hours to obtain a rubber composition containing silica-modified carbon black for rubber reinforcement (master batches 1 to 7).

Silica of modified carbon black for rubber reinforcement
The content of the modified carbon black sample was incinerated at 600 ° C. in an electric furnace, the ash was fluorinated, and the weight loss was attached as silica, and the weight fraction of silica relative to the original modified carbon was 1
0% by weight and 1% by weight were confirmed.

Various rubber compositions were kneaded with a Banbury mixer and a roll machine according to the following formulas according to a conventional method (vulcanization conditions: 160 ° C. × 30 minutes). The results are shown in Table I.

Compounding Table 1 Diene rubber (SBR1502): 100 parts by weight ^{* 1} Reinforcing filler (see Table I) 50 parts by weight ^{* 1} Silane coupling agent ^{* 2} : 3 parts by weight ^{* 3} Zinc white (JIS No. 3): 3 parts by weight Stearic acid: 2 parts by weight Antioxidant ^{* 4} : 2 parts by weight Powdered sulfur: 2 parts by weight Vulcanization Accelerator ^{* 5} : 1 part by weight ──────────────────────── * 1) Wet master batch * 2) Si 69 (made by Degussa) * 3 Not used when reinforcing filler is carbon black. * 4) Santoflex 13 (Monsant) * 5) Santocure NS (Monsant)

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

[0033]

As is evident from the results of Table I, the method for producing the rubber composition containing water-dispersed silica-modified carbon black for rubber reinforcement according to the present invention is the same as that of a conventional carbon masterbatch, and is simple and inexpensive. Can be manufactured, and the resulting composition is also compared to carbon black,
The tan δ in the high temperature range (60 ° C.) is low, and the wear resistance does not decrease.

Claims (8)

[Claims] 1. (a) Latex 1 of a diene rubber component
Slurry containing 00 parts by weight (as solid content) and (b) water-dispersed silica and carbon black for reinforcing rubber 10 to 25
0 part by weight (as solid content) and then coagulating the mixture with a coagulant to produce a rubber composition containing a modified carbon black for reinforcing rubber. 2. The production method according to claim 1, wherein the carbon black for rubber reinforcement before the silica is attached is a GPF or SAF grade produced by an oil furnace method. 3. An aromatic processing oil and / or a high-viscosity oil 5.
The production method according to claim 1, wherein the mixture further contains １５０150 parts by weight. 4. The method according to claim 1, wherein the silica content is 0.1 to 25% by weight of the modified carbon black. 5. (a) Latex 1 of diene rubber component
100 parts by weight (as solid content) and (b ') modified carbon black modified and granulated by adding water-dispersed silica.
0 part by weight and then coagulating the mixture to produce a carbon black-containing rubber composition. 6. The water-dispersed silica contains silica particles having a diameter of 1 nm to 100 nm, and has a sodium ion content of N.
The process according to claim 5 in a ₂ O conversion is 1.0 wt% or less. 7. Aromatic processing oil and / or high viscosity oil 5
The method according to claim 5, wherein the mixture further comprises 150 parts by weight. 8. The method according to claim 5, wherein the silica content is 0.1 to 25% by weight of the modified carbon black.