JPS58152031A - Rubber composition - Google Patents

Abstract

PURPOSE:A rubber composition, obtained from a latex mixture of a styrene- butadiene rubber latex with a polybutadiene rubber latex and a styrene-butadiene rubber latex, and having improved abrasion and wet skid resistance. CONSTITUTION:A rubber composition obtained by incorporating (A) preferably 20-80wt%, based on the solid content, stytene-butadiene rubber latex having 30wt% or more bound styrene content with (B) preferably 80-20wt%, based on the solid content, polybutadiene rubber latex and/or styrene-butadiene rubber latex having 15wt% or less bound styrene content, and if necessary carbon black, various oils, inorganic filler, antioxidant, pigment, etc., coagulating, dehydrating and drying the resultant mixture. USE:Tire treads, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a rubber composition obtained from a latex mixture in which 10% of rubber is mixed, each in a latex state. Specifically, the present invention relates to a rubber composition that has good abrasion resistance and wet skid resistance and is useful as a rubber for tires.

As is well known, styrene tadiene rubber (hereinafter referred to as 8BR) is the main synthetic rubber that established the current synthetic rubber era. Generally synthesized by emulsion polymerization, it accounts for approximately 40% of all synthetic rubber produced and shipped by your company, and is used in a wide variety of rubber products. In particular, it has an overwhelming consumption record for passenger car tires, which are the main product of rubber products.

In the field of passenger car tires, 1I, which has a combined styrene content of 13.1% by weight, is the most popular because of the balance between processability and physical properties.
B1t has been used for a long time, but in recent years, due to social demands for resource and energy conservation, there has been an urgent need to consider fuel-efficient tires in connection with the development of automobiles that consume less gasoline.

On tires! ! Tire tread performance is one of the seven performance requirements. At present, the most important aspects of tire tread performance are low rolling resistance, which is the ability to accurately transmit engine output to the road surface without consuming it in the tire, and braking performance, which is essential for vehicle safety, especially in the rain. day's braking performance,
That is, wet skid resistance.

However, Jin's two properties are in a so-called antinomic relationship, meaning that improving one property will worsen the other.91 It was thought that it would be impossible to break away from this relationship as long as existing rubber materials were used.

An important aspect of tire tread performance is wear resistance, which is important from the perspective of resource conservation.

However, in this case as well, abrasion resistance and wet skid resistance have a trade-off relationship, similar to the relationship between transfer resistance and wet skid resistance.

Some of the present inventors previously proposed a rubber composition C% consisting of 8BR with a high styrene content and BBB with a low styrene content.
2/JJ-JJ) and a rubber composition consisting of natural rubber and 81R with a low styrene content (% GanshojA-ColJjCo/), but the blend state of these rubber compositions is macroscopically homogeneous. In terms of constant chromatography, it is in a non-uniform state, that is, in an electron microscope field, it looks like a sea-island.9 When used as a tire, the complicated tire trend overall performance balance as mentioned above is difficult to achieve. Gives you improved tires.

By the way, conventionally, rubber compounds have been made with very high raw materials.
The polymer latex obtained by polymerizing is coagulated, dehydrated,
Normal 703 X J j Tan ×-〇a with compressed bottom plate after drying
It is manufactured by kneading a solid product (pail) of several Sa in size -Q to #1i clothes using a large machine such as a Banbury mixer or an oven roll.

However, in order to obtain a blend in which each component is macroscopically homogeneous by veil blending two or more types of rubber components in this manner, a large amount of energy is required.

Therefore, the present inventor, Gin, conducted intensive studies to easily provide a rubber composition with well-balanced physical properties, and the following results were obtained.
When each rubber component is blended in a latex state, it becomes more homogeneous macroscopically.

Furthermore, the inventors have discovered that it is possible to easily obtain a microscopically non-uniform blend, thereby achieving the desired objective, and have completed the present invention.

That is, 1) the gist of the present invention is that the amount of bound styrene is 30
Heavy windward styrene-butadiene rubber latex and (
A rubber composition obtained from a latex mixture with a truncated polygetadiene rubber latex and a styrene-butadiene rubber latex having an amount of /l or bound styrene of less than lj weight.

To explain the present invention, the amount of bound styrene, which is the rubber component of the present invention, is J o-4]t% or more, preferably 100% by weight or less, is a styrene-butane, diene rubber latex (
Hereinafter referred to as high styrene 81R latex, polybutadiene rubber latex (hereinafter referred to as EBR latex)
and the amount of bound styrene is less than or equal to the amount by weight, preferably.

Styrene-butadiene rubber latex (hereinafter referred to as low styrene 8% by weight) preferably 10% by weight or more and 11% by weight or less
BR latex and c) can be obtained according to known emulsion polymerization methods.

Specifically, for example, d% mBR latex is prepared according to the method described in Japanese Patent Publication Akihiro J-/47111/C.
, 3-butadiene monomer is emulsified and dispersed in an aqueous medium using an emulsifier, and a polymerization reaction is caused by adding a polymerization initiator.

In addition, high styrene-8B only latex or low styrene 8BR latex contains styrene monomer and/or J
- It can be obtained by similarly emulsifying and dispersing butadiene monomer in an aqueous medium and adding a polymerization N initiator to cause a p,x reaction.

Emulsifiers used include Fi, fatty acid soap, rosin acid soap, naphthalene sulfonic acid soda foshimarin m compound. Anionic surfactants such as sodium alkylbenzene sulfonate are common.

As a polymerization initiator, it is a so-called hot rubber formulation that performs polymerization at a high temperature of 10-40°C.

Potassium persulfate is used, and Fi, a redox initiator, is used in a cold tube formulation that polymerizes at 0-10°C.

As a redox initiator, a combination of an organic peroxide such as Kuhn's hydroperoxide, diisopropylbenzene hydroperoxide, or para-menthane hydroperoxide and iron sulfate is generally used, and sulfoxylate, etc. is used as a reducing agent. are used together.

Furthermore, when polymerizing the BR latex, nitrobenzene can be added to the polymerization system to improve linearity.

When obtaining cibolyptadiene rubber or styrene-butadiene rubber by ordinary emulsion polymerization.

Polymerization reaction rate! ! ~t! When the temperature reaches -, a polymerization terminator such as thorium, dimethyldithiocarbamate, or Silua 27 in diethylhydro is added to stop the first polymerization reaction. Furthermore, unreacted monomers are stripped with steam or the like to form EIR texex, high styrene 8BR latex, or low styrene 8 BR latex.
11R latex can be obtained.

Next, the high styrene 8BR latex, IBR latex and/or low styrene 8BR latex are mixed.

In the present invention, since the rubber components are mixed in a two-technique state, a mixture can be easily obtained.

Usually, high styrene 8BN') TEX is -0-10 weight-1 in terms of solid content, preferably 30 to 96.
Particularly preferably, IBR latex and/1 or low styrene 8BR cutex is added to 1O-JO weight qh1 in terms of solid content, preferably 70
-20 weight ts, particularly preferably in the range of 11 to 1 weight.

The rubber composition of the present invention can be obtained by coagulating, dehydrating, and drying the latex mixture thus obtained according to a conventional method.

Carbon black is usually added to the rubber composition of the present invention. Any known carbon black can be used, but when used as a rubber compound for tires, II! 1 has an iodine adsorption amount (A) of 70 to 1λOg
M#/f1 dibutyl 7 tallate oil absorption (DBP) is 10
-/JOd/100f is preferred.

Two car pumps are usually added in an amount of 0 to 100 parts by weight, preferably 50 to 10 parts by weight, per 100 parts by weight of the rubber component, and kneaded.

Further, the rubber composition of the present invention includes aromatic foil h f 7 ten oil, par? fin oil, tall oil,
Stearic acid, general rubber chemicals such as wax, and, if necessary, various other compounds, such as 1 silica, inorganic chemicals such as calcium carbonate, M-phenyl-N'-(
It is also possible to add an anti-aging agent such as i,J-dimethylbutyl)-p-phenylenesiaden, pigments, fibers, etc. Particularly, when aromatic foil, F-7 ten oil, or fragrant oil is added in an amount of 70 parts by weight or less, preferably 10-to parts by weight, based on 10 parts by weight of the rubber component.

This is preferable because it improves workability.

In the present invention, the latex mixture can also be used as a carbon black masterbatch in which carbon black, oil, etc. are mixed in advance by a wet method.

Incidentally, the vulcanization or crosslinking of the rubber can be carried out by adding a vulcanizing agent such as sulfur and, if necessary, a vulcanization accelerator, or by adding peroxide or azun.

This is done by crosslinking using metal salts, radiation, etc. Rubber vulcanization or crosslinking is usually done.

This is carried out after mixing the above-mentioned components using a Banbury mixer, an open roll, etc.

The present invention has been described in detail above, but if utex blending is performed according to the present invention, the energy consumption required for blending high styrene 8BR and/or low styrene SBH can be reduced, and the resulting rubber composition is This tire has better workability than the conventional 8BRK.

It can be advantageously used in various applications such as belt conveyors, anti-vibration rubber, and fenders. In particular, the rubber composition of the present invention has simultaneously improved wet skid resistance and abrasion resistance without impairing rolling resistance, so when used for tire treads, it will significantly improve automobile safety and tire life. I can do it with Jin.

EXAMPLES The present invention will be further explained in detail by giving examples below.

Example/High styrene 8B obtained by emulsion polymerization and shown in Table 1 below
R? The latex and FfBR latex and/or low styrene 8BR latex were mixed at the blending ratios shown in Table 1 (in terms of solid content) to obtain a latex mixture.

Next, this latex mixture is coagulated, dehydrated, and dried to obtain a rubber composition.

With respect to ioo parts by weight of this rubber composition, as other components,
Carbon black (M-33ri) Otsu! Adding parts by weight, aromatic oil JJ parts by weight, stearic acid/parts by weight, anti-aging agent - parts by weight, zinc oxide parts by weight, sulfur parts by weight, and 1.7 parts by weight of a vulcanization accelerator, Kobe Steel J1
11 o o c type Banbury mixer (circulating water temperature 70℃
, rotor rotation speed zu, 5(1)/4λ-J (vk)
Then, the unvulcanized rubber sheeted with an open roll was press-vulcanized at 1zzc for 30 minutes to obtain a molded sample.

From the sample obtained here, the length is 10cm.

width! - test pieces were punched out and subjected to a viscoelastic spectrometer test.

Viscoelastic spectrometer (manufactured by Iwamotodono Seisakusho) was used under the conditions of a temperature range of -ioo°C to +lO'C% and a frequency of 10 Hz to perform a dynamic #j test to determine the mechanical loss tangent (-δn).

Wet skid resistance was measured using a Votaple wet skid tester (manufactured by 8Tanley, road surface: Safety Walk TRP@B, manufactured by 3M, water temperature: 0° C.).

The wear resistance index is 69, which is the average value of Akron wear and Pico wear data. The larger the index, the better.

The power consumption of the Banbury mixer can be measured using a power meter connected directly to the drive motor power supply.

The results of Jinre et al. are shown in Table 3.

In addition, the glass transition point ('l) of the vulcanized and molded sample was determined using a differential scanning calorimetry needle (D80), and one glass transition point unique to each of the rubbers of Ku, Niro, High Styrene 8BR, and Low Styrene 8BR was determined. It was found that this sample was in a Miku non-uniform state.

For comparison, the physical properties of rubber compositions obtained in the same manner as in each example except that the veil blend rubber shown in Table 1 or the standard EIBRt with a bound styrene content of 23.3 weight were used as the rubber component are shown below. Also included in the reference.

Claims (3)

[Claims] (1) Styrene-butadiene rubber latex with a bound styrene content of 30 weight or more and (g) polybutadiene rubber latex and /l or a bound styrene content of lj
A rubber composition obtained from a latex mixture with a styrene-butadiene rubber latex below the mold weight. (2) The amount of (trans)bonded styrene in the latex mixture is
The styrene-butadiene rubber latex on a 30-weight plate and the styrene-butadiene rubber latex (tetrapolygetadiene rubber latex and /Makusha styrene-butadiene rubber latex with a combined styrene content of /j weight or less) were each weighed 20% in terms of solid content. 10. The rubber composition according to claim 1, which is obtained by mixing 10 to 0% by weight. (3) The rubber composition according to claim 1 or 2, wherein the latex mixture contains carbon black or oil.