KR20020089894A - Masterbatch for tire rubber composition - Google Patents

Abstract

PURPOSE: Provided is a master batch for a tire rubber composition, which comprises a natural rubber and a vulcanizing agent and is excellent in processability and dispersibility. CONSTITUTION: The master batch for the tire rubber composition comprises 10-40wt% of the natural rubber and 60-90wt% of the vulcanizing agent containing a vulcanizing accelerator, wherein the vulcanizing agent is sulfur or insoluble sulfur and the vulcanizing accelerator is selected from the group consisting of dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazyl sulfenamide, N-tert-butyl-2-benzothiazyl sulfenamide, and etc.

Description

Masterbatch for tire rubber composition

The present invention relates to a master batch for tire rubber composition, and more particularly, to a master batch made of natural rubber as a base rubber and a large amount of vulcanizing agent added thereto, and used for the tire rubber composition.

The various vulcanizing agents and vulcanization accelerators used in the rubber for tires are in the form of powder and are used in small amounts compared to other compounding agents, but they are rubber chemicals that greatly affect the physical properties of the rubber. When the vulcanizing agent and the vulcanizing accelerator are added to the banbari mixer or open roll for mixing with the other components of the tire rubber composition, it is a small amount of powder, which causes loss and causes pollution of the surrounding environment. The loss of these chemicals due to the device, etc. is a cause of quality deviation of the compounded rubber.

In addition, these vulcanizing agents are difficult to improve the dispersibility due to the binding force acting between these particles during mixing with the rubber, which leads to a decrease in the rubber properties. As a means for improving this, the mixing time of the rubber is generally extended. In this case, there is a problem in that manufacturing costs such as processing costs are increased.

In order to solve such a series of problems, 'batch' mixed with rubber in vulcanizing agents and vulcanization accelerators in a certain ratio is manufactured and added to the rubber composition in the form of plate or pellet to prevent the loss of chemicals and to prevent environmental pollution and By weakening the bonding strength between the mixed particles, it is possible to improve the dispersibility in the mixing process.

In general, since the master batch is not easy to manufacture, the rubber to be mixed during manufacture is SBR (styrene-butadiene rubber) which is easy to disperse powder and is easily extruded or rolled to form a plate or pellet. It is common to use relatively low molecular weight rubber such as EPDM (ethylene-propylene-diene monomer), and the chemical content in the masterbatch had to be lowered. As a result, the rubber composition for tires manufactured using the master batch thus prepared was limited due to the deterioration of physical properties.

As an example of the preparation of a specific masterbatch, US Pat. No. 5,284,907 discloses a masterbatch obtained by emulsion polymerization of a conjugated diene monomer copolymerizable with a functionalized monomer containing a polymerizable vinyl group.

In Japanese Patent Application Laid-Open No. 1996-87889, a masterbatch containing peroxide is disclosed, wherein saturated nitrile copolymer rubber is used as the basic rubber.

In Japanese Patent Laid-Open No. 1997-278946, a master obtained by using a halide polymer such as chlorinated polyethylene as a main binder and blending a carbonate or oxide of a sulfide compound, a sulfenamide compound, a mercaptan compound, and an alkali transition metal Deployment is disclosed.

In addition to the master batch as described above, various master batches and a method of manufacturing the same are known, but the rubber is a synthetic rubber system.

However, in recent years, rubber tends to be mixed in an open roll in addition to the banbari mixer. In this case, unlike an internal mixer such as the banbari mixer, the mixing is performed outside of the facility, so when powder is used, Losses occur and cause quality problems.

Open roll formulation is mainly used to mix the rubber composition based on natural rubber, it is necessary to use a master batch based on natural rubber in order to prevent the physical properties of the rubber composition.

However, until now it has been extremely limited to use a master batch in the rubber composition for tires, and when manufacturing a master batch using natural rubber, the masterbatch based on natural rubber is extremely rare due to disadvantageous manufacturing processability.

As an example of a master batch based on natural rubber, Japanese Patent Application Laid-Open No. 1996-20677 discloses 50 to 80% by weight of a drug such as a vulcanizing agent or a vulcanizing accelerator, and made of natural rubber or isoprene rubber and ethylene-vinylacetate copolymer, except ethylene. -Vinyl acetate copolymer is disclosed for the masterbatch obtained by mixing 10-40 weight% of rubber which is 70 weight% or less of rubber component, 10-40 weight% of adsorbent powder, naphthenic oil or dibutyl phthalate, and 20 weight% or less of fatty acid. Doing.

Although the masterbatch disclosed herein illustrates that it can be used as a basic rubber rather than a synthetic rubber, it is necessary to include a large amount of ethylene-vinylacetate copolymer and the like in the rubber component and to use an adsorbent powder. It is complicated and its practical use is limited. In addition, the adsorbent ethylene-vinylacetate and the adsorbent powder used are likely to cause a decrease in physical properties in the composition for tire rubber, which requires great reinforcement.

Thus, the inventors of the present invention are limited in the use of a master batch based on some synthetic rubber, and while trying to solve the compositional limitation of the master batch containing a part of natural rubber, other synthetic rubber components are not contained at all. Instead of using only natural rubber as a base rubber, and increasing the chemical content of the vulcanizing agent, it was found that there is no problem in processability and that the blendability in the Banbari mixer is also improved, thereby completing the present invention.

Accordingly, it is an object of the present invention to provide a masterbatch for tire rubber having no problem in workability and having good dispersibility.

The masterbatch for tire rubber of the present invention for achieving the above object is characterized by consisting of 10 to 40% by weight of natural rubber and 60 to 90% by weight of a vulcanizing agent.

The present invention will be described in more detail as follows.

The present invention relates to a master batch using natural rubber, the use of natural rubber as the basic rubber of the masterbatch can be wider range of use compared to SBR or EPDM, and furthermore, the main component is a natural rubber that is processed in an open roll It can be used easily for mix | blending of the rubber composition for tires to make.

However, in practice, natural rubber except for the vulcanizing agent is an auxiliary material for manufacturing the master batch, and when used in rubber compositions, the amount of vulcanizing agent should be increased as much as possible. However, if the content of the vulcanizing agent is excessively increased, it is difficult to prepare the master batch due to difficulty in mixing, extruding, rolling, etc. during the production of the master batch, and if the content is too small, the natural rubber in the master batch in the rubber composition The addition of a large amount can lead to a change in the physical properties of the rubber composition, and also to avoid equipment problems and time loss due to excessive metering when weighing the masterbatch for input into an open roll or semi-barrier mixer, and for complete dispersion thereof during mixing. There may be a problem of a decrease in productivity due to the extension of the mixing time. Thus, the preferred amount of vulcanizing agent is 60 to 90% by weight of the total masterbatch composition.

The vulcanizing agent which may be used herein is a generic term for vulcanizing agents and vulcanization accelerators that can be used in rubber compositions for tires, and specific vulcanizing agents include sulfur or insoluble sulfur, and vulcanization accelerators include dibenzothiazyl disulfide (dibenzothiazyl). disulfide), N - cyclohexyl-2-benzothiazole sulfene amide quality (N -cyclohexyl-2-benzothiazyl sulfenamide ), N - tert - butyl-2-benzothiazole sulfene amide quality (N - tert -butyl-2- benzothiazyl sulfenamide there may be mentioned the promoter acids including diphenyl guanidine (N, N -diphenyl guanidine) - ), hexamethylene tetraamine (hexamethylene tetramine), tetramethyl thiuram disulfide (tertamethyl thiuram disulfide), N, N. However, it is not limited to this.

Thus, even if made of only natural rubber and vulcanizing agent, there is no deterioration in processability or physical properties, but may also include a processing aid to improve the processability by using natural rubber. In other words, when using a masterbatch using natural rubber having a high molecular weight as a basic rubber, some vulcanizing agents are difficult to process in the manufacturing process for mixing and mixing them into plates or pellets. A certain amount can be used.

As the processing aid, fatty acid esters and hydrocarbon compounds, specifically, fatty acid esters and hydrocarbon compounds having a melting point of 35 to 100 ° C., stearic acid, fatty acids, etc. may be used. It is preferable that it is 100 parts by weight or less with respect to. If the added amount is more than 100 parts by weight based on 100 parts by weight of natural rubber, the prepared masterbatch is too soft and may cause problems with the masterbatch particles or facilities during storage, transport and weighing thereof.

In addition, depending on the type of vulcanizing agent, it may be possible to use Soviet accelerators to soviet the natural rubber used during process oil or masterbatch manufacture, if necessary.

Process oil may include naphthenic oil, paraffin oil or aromatic oil generally used in the tire industry. When the process oil is added, the content thereof is preferably 100 parts by weight or less with respect to 100 parts by weight of the natural rubber. If the content is more than 100 parts by weight, the master batch manufactured as in the case of using a large amount of processing aid is too soft to During storage, transport and weighing, problems may arise with the masterbatch particles or with the equipment.

The masterbatch according to the present invention does not need to separately mix synthetic rubber with natural rubber and can exhibit excellent processability and dispersibility without adding various additives and the like.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Preparation Example 1

Masterbatch was prepared by mixing 80% by weight of insoluble sulfur in 20% by weight of natural rubber (SMR-5L) using a fatty acid ester and 1% by weight of a hydrocarbon compound as a processing aid. This is called 'MB 1'.

Preparation Example 2

Masterbatch was prepared by mixing 75 wt% of insoluble sulfur with 25 wt% of natural rubber (SMR-5L). This is called 'MB 2'.

Preparation Example 3

Masterbatch was prepared by mixing 70 wt% of insoluble sulfur with 30 wt% of natural rubber (SMR-5L). This is called 'MB 3'.

Preparation Example 4

Masterbatch was prepared by mixing 65 wt% of insoluble sulfur with 35 wt% of natural rubber (SMR-5L). This is called 'MB 4'.

Preparation Example 5

To 15% by weight of natural rubber (SMR-5L), 80% by weight of N, N-dicyclohexyl-2-benzothiazylsulfenamide, 1% by weight of naphthenic oil, and 4% by weight of fatty acid ester and hydrocarbon compound as a processing aid Mixing made a masterbatch. This is called 'MB 5'.

Comparative Production Example 1

A masterbatch was prepared by mixing 80% by weight of insoluble sulfur in 20% by weight of styrene-butadiene rubber. This is called 'PMB 1'.

Comparative Production Example 2

A masterbatch was prepared by mixing 50 wt% of insoluble sulfur with 50 wt% of natural rubber (SMR-5L). This is called "PMB 2".

Examples 1-5 and Comparative Examples 1-3

Rubber compositions for tires were prepared using the masterbatches obtained according to Production Examples 1 to 5 and Comparative Production Examples 1 to 2 as shown in Table 1 below.

Hardness, 200% modulus, elongation, tensile strength and chemical dispersibility of the obtained specimens were measured. The vulcanization conditions for the evaluation of the properties were carried out at 150 ° C. for 30 minutes, and the mixture was mixed for 45 seconds using a 255 L half-barrier mixer. It was.

The chemical dispersibility is obtained by mixing rubber using a half-barrier mixer, making a sheet using a sheet control, and then randomly taking 10 specimens to obtain the maximum torque point using MDR (Alpha Tech). Obtain the coefficient of variation from The lower the coefficient of variation (CV), the better the dispersibility.

Physical property evaluation results are shown in Table 1 below.

Example Comparative example One 2 3 4 One 2 3 Composition (part by weight) Natural rubber 100 100 100 100 100 100 100 Carbon black 60 60 60 60 60 60 60 Vulcanizer MB 1 (12.5) MB 2 (12.5) MB 3 (12.5) MB 4 (12.5) Insoluble Sulfur Powder (10) PMB 1 (12.5) PMB 2 (12.5) Vulcanization accelerator MB 5 (1.25) MB 5 (1.25) MB 5 (1.25) MB 5 (1.25) N, N-dicyclohexyl-2-benzothiazyl sulfenamide powder PMB 1 (1.25) PMB 1 (1.25) Properties Hardness 76 76 76 75 76 76 74 200% Modulus (kg / ㎠) 140 140 138 137 138 135 130 % Elongation 320 325 330 340 318 270 380 Tensile Strength (kg / ㎠) 243 242 240 238 239 212 196 Chemical Dispersibility (CV) 2.63 2.75 2.78 3.21 9.45 2.58 3.85

The vulcanizing agent 12.5 and the vulcanizing accelerator 1.25 in the above examples are parts by weight of the drug substance based on 100 parts by weight of rubber, and this weight was calculated and used based on the drug content included in the master batch (for example, insoluble in case of MB1). When sulfur was 80% by weight, MB1 used 12.626% by weight.)

From the results of Table 1, it can be seen that the dispersibility of the drug is improved both when the natural rubber or synthetic rubber is prepared by the addition of the master batch, but the master batch obtained by mixing the vulcanizing agent above a certain content based on the natural rubber In the case of using, it can be seen that the physical properties such as modulus, elongation and tensile strength are excellent.

As described in detail above, when the master batch obtained by using natural rubber as a base rubber and containing a large amount of a vulcanizing agent is added as a vulcanizing agent to the tire rubber composition, it is added as a chemical agent instead of a master batch. Compared with the masterbatch manufactured with synthetic rubber as the basic rubber, it can solve the problem of powder dissipation and excellent dispersibility, and it can not only improve other physical properties but also mix with other synthetic rubber or absorbent powder. Excellent workability and dispersibility can be exhibited without addition, which is particularly useful for the production of rubber for tires, which is blended in an open roll.

Claims (5)

A master batch for tire rubber composition consisting of 10 to 40% by weight of natural rubber and 60 to 90% by weight of vulcanizing agent. The masterbatch for tire rubber composition according to claim 1, wherein the vulcanizing agent comprises a vulcanizing agent and a vulcanizing accelerator. The method of claim 2, wherein the vulcanizing agent is sulfur or insoluble sulfur and a vulcanization accelerator is dibenzothiazyl disulfide (dibenzothiazyl disulfide), N - cyclohexyl-2-benzothiazole sulfene amide quality (N -cyclohexyl-2-benzothiazyl sulfenamide ) , N - tert - butyl-2-benzothiazole sulfene amide quality (N - tert -butyl-2- benzothiazyl sulfenamide), hexamethylenetetramine (hexamethylene tetramine), tetramethyl thiuram disulfide (thiuram disulfide tertamethyl) and N, N Masterbatches for the composition of tire rubbers, characterized in that selected from the group consisting of diphenyl guanidine ( N, N -diphenyl guanidine). The method of claim 1, wherein the master batch further comprises a processing aid selected from the group consisting of fatty acid ester and hydrocarbon compound having a melting point of 35 to 55 ℃ 100 parts by weight or less based on 100 parts by weight of the natural rubber Masterbatch for Tire Rubber Composition. The master batch of claim 1, wherein the master batch further comprises process oil so that the process oil is 100 parts by weight or less with respect to 100 parts by weight of the natural rubber.