KR20100093688A - The manufacturing method of titanium dioxide modified surface and tire rubber with great reinforcement - Google Patents

Abstract

PURPOSE: A manufacturing method of a titanium dioxide, and a tire rubber composition using thereof are provided to improve the photo catalytic activity, the acid/alkali resistance, and the ultraviolet ray aging prevention property of the tire rubber composition. CONSTITUTION: A tire rubber composition contains the following: crude rubber including more than two components selected from natural rubber and synthetic rubber; a titanium dioxide surface modified with a hydroxyl group; and an additive containing more than two components selected from the group consisting of a filler, a reinforcing agent, and a coupling agent.

Description

The manufacturing method of Titanium dioxide modified surface and Tire rubber with great reinforcement}

 The present invention relates to a tire tread rubber having improved reinforcement through a titanium dioxide and a coupling agent whose surface is modified with a hydroxyl group in order to improve anti-aging characteristics and wet road braking characteristics of the tire tread rubber.

In general, calcium carbonate, clay, silica, and the like are used as fillers in white rubber compositions of tires or other rubber products, and titanium dioxide is mainly applied as colorants. In particular, the white sidewall rubber is a tire part exposed to sunlight, which is problematic due to UV aging and oxidation by ozone, and thus the fatigue resistance and tensile properties are important factors.

Titanium dioxide in the white rubber composition by the prior art in the prior art to brighten the color of the rubber, is added as a sunscreen (KR 10-1998-0022349), titanium dioxide as a pigment in order to improve the discoloration resistance in the rubber composition It is applied to the colored tread rubber composition for tires (KR 10-1998-0042584). However, the titanium dioxide in the white rubber composition is incompatible with the rubber, weak dispersibility, and the reinforcing effect is insignificant to the severe rotational movement in direct contact with the road surface and difficult to apply to the tread rubber composition exposed to the outside. Therefore, the present invention is the acid treatment of existing conventional titanium dioxide To modify the surface through the use of coupling agents to provide reinforcement improvements. Of course, even if it is applied as a side wall rubber, the performance is better.

In order to improve the reinforcement of the inorganic compound powder when the conventional inorganic compound powder is applied to the tread rubber composition In the production of dispersion-based composite materials composed of inorganic compound powders and organic polymers, various coupling agents are used to improve the affinity between materials such as surface modification of inorganic powders or matrix modifications to introduce polarity into organic polymers. A rubber composition is prepared (US2006 / 01731, US6699924, US6835769) and a rubber composition which improves UV and discoloration resistance through surface modification of titanium dioxide (US5240056, US 2003/0069332).

This conventional technique is applied to the tread rubber by applying a surface modified titanium dioxide and a coupling agent to improve the reinforcement, but the surface modification method is difficult, there are significant constraints on the processing conditions, the optimum ratio between the mixture There is a difficulty that is difficult to decide.

Recently, in the automobile industry and the tire industry, there is an increasing demand for environmentally friendly tires that are excellent in preventing photoaging and have excellent surface braking characteristics.

Accordingly, the present inventors have endeavored and researched to solve the problems of the existing tire application and meet the demands of the industry, and have come up with a method of modifying the surface of titanium dioxide with hydroxyl, and the surface-modified dioxide with such hydroxyl group. The purpose is to provide a tire tread rubber with improved properties by introducing titanium.

Tire tread rubber of the present invention for solving the above problems is a raw material rubber containing one or two or more selected from natural rubber and synthetic rubber; Titanium dioxide surface-modified with hydroxyl groups; And additives containing one or more selected from fillers, reinforcing agents and coupling agents.

In addition, the present invention relates to a method for producing titanium dioxide surface-modified with a hydroxyl group, after adding titanium dioxide having an anatase structure in a solution of nitric acid (HNO ₃ ) and distilled water in a ratio of 1: 7 to 9 by weight And the surface of the titanium dioxide is modified with a hydroxyl group by heating at a temperature of 90 ° C. or higher.

The tire tread rubber of the present invention is not only excellent in UV anti-aging characteristics and wet road braking characteristics, but also due to the action of the hydroxyl group and the coupling agent present on the modified surface of titanium dioxide when the coupling agent is further introduced. The reinforcement of the tread rubber can be greatly improved.

This invention will be described in detail below.

Tire tread rubber of the present invention is a raw material rubber containing one or more selected from natural rubber and synthetic rubber; Titanium dioxide surface-modified with hydroxyl groups; And additives containing one or more selected from fillers, reinforcing agents and coupling agents. It characterized by including the.

Each of these compositions of the present invention will be described in more detail.

1. Raw material rubber

The raw material rubber to be used in the present invention is not particularly limited, and any rubber can be used as long as it can apply surface modified titanium dioxide.

The raw material rubber may be one or two or more selected from natural rubber and synthetic rubber. The synthetic rubber may be a diene polymer synthetic rubber, a diene copolymer synthetic rubber, a nitrile rubber, a butyl rubber, a urethane rubber, and ethylene-propylene. Preference is given to using one or two or more selected from rubbers. In addition, the synthetic rubber is more preferably used one or two or more selected from polybutadiene rubber, styrene-butadiene rubber and polyisoprene rubber.

2. With hydroxyl Surface modified  Titanium dioxide

The titanium dioxide surface-modified with one of the components of the present invention is a titanium dioxide having an anatase crystal structure in a solution in which nitric acid (HNO ₃ ) and distilled water are mixed at a weight ratio of 1: 7-9, 90 ° C. The surface of the titanium dioxide is modified with a hydroxyl group by heating at the above temperature, and the heating is appropriate for about 7 to 9 hours.

Titanium dioxide surface-modified with the hydroxyl group overcomes van der Waals forces between materials and facilitates dispersion, and when a coupling agent is used, it increases the bonding strength with rubber, thereby improving mechanical properties, particularly reinforcement of tire tread rubber. You can.

Titanium dioxide surface-modified by the hydroxyl group is preferably used that can be blended with other inorganic powders and general carbon black, the inorganic powder is at least one selected from calcium carbonate, clay, silica and Fensens carbon black Include.

In the present invention, the surface-modified titanium dioxide may be used 1 to 70 parts by weight based on 100 parts by weight of the raw material rubber, preferably 1 to 40 parts by weight, more preferably economics and effects It is recommended to use 2 to 20 parts by weight. At this time, when the amount of the titanium dioxide surface-modified by the hydroxyl group is less than 1 part by weight, the effect of UV aging, wet road braking and reinforcement may not be increased, and when it exceeds 70 parts by weight, the workability and physical properties of the tire tread rubber may be deteriorated. It is recommended to use it within the above range as it may .

It is preferable to use titanium dioxide having an average diameter of 10 to 500 nm and a BET surface area of 10 to 200 m ² / g, but having an average diameter of 10 nm is too expensive and uses a surface of more than 500 nm in small specific surface area. Since the reinforcement property is reduced, it is better to use the thing within the said range.

3. Additive

The additive, which is a component of the present invention, is characterized in that it contains one or two or more selected from fillers, reinforcing agents, and coupling agents, and the additives include one or two or more selected from vulcanizing agents, vulcanizing agents, and vulcanization accelerators. It may contain more.

The type and amount of the fillers, vulcanizing agents, vulcanizing agents, vulcanization accelerators and reinforcing agents are not particularly limited in the present invention, and those generally used in the art may be used.

The coupling agent which is one of the additive components will be described in detail.

Inorganic powders, such as silica, serve to bond between the inorganic powder and the rubber as a binder in the rubber composition and the inorganic powder serves to facilitate dispersion in the rubber matrix. That is, the coupling agent forms a sufficient chemical and physical bond between the filler and the reinforcing agent and the rubber and has at least two functional groups.

                       A-C-B

A represents a group of functional groups capable of chemically and physically bonding inorganic powders. For example, in the present invention, A represents a hydroxyl group on the surface of titanium dioxide.

B represents a group of functional groups capable of chemically and physically bonding to rubber.

C represents a hydrocarbon group connecting A and B.

The coupling agent, which is one of the components of the present invention, is bis (3-triethoxysilypropyl) tetrasulphide, TESPT, [(C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ S ₂ ] ₂ )}, bis (triethoxysilypropyl) disulphide, TESPD [(C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ S] ₂ )}, Bis (triethoxysilypropyl) monosulfide {bis (triethoxysilypropyl) monosulphide, TESPM, [(C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ S (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ ]} , Bis (triethoxysilyl) ethane {bis (triethoxysilyl) ethane, ETES, [(C ₂ H ₅ ) ₃ Si (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ ]}, bis (triethoxysil) Hexane {bis (triethoxysilyl) hexane, HTES, [(C ₂ H ₅ O) ₃ Si (CH ₂ ) ₆ Si (OC ₂ H ₅ ) ₃ ]}, bis (triethoxysilyl) decane {bis (triethoxysilyl) decane , DTES, [(C ₂ H ₅ O) ₃ Si (CH ₂ ) ₁₀ Si (OC ₂ H ₅ ) ₃ ]} and γ-mercaptopropyltriethoxysilane {γ-mercaptopropyltriethoxysilane, MPTES, [(C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ SH]} It is preferable to use one or two or more selected from.

The coupling agent is preferably used 0.5 to 5 parts by weight based on 100 parts by weight of the raw material rubber, wherein when the amount of the coupling agent used is less than 0.5 parts by weight, the reinforcement improvement of the tire tread rubber is poor, and when it exceeds 5 parts by weight Since the hardness of the tire tread rubber may be too large and the elongation may decrease, it is preferable to use it within the range suggested by the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the technical scope of the present invention is not limited by the examples.

EXAMPLE

Production Example

With hydroxyl Surface modified  Preparation of Titanium Dioxide

A solution was prepared by mixing and stirring nitric acid (HNO ₃ ) and distilled water in a beaker at a weight ratio of 1: 8, and then adding titanium dioxide having an anatase structure having an average diameter of 50 nm and a BET surface area of 100 m ² / g. . The solution to which titanium dioxide was added was heated at a temperature of 90 ° C. or more for about 8 hours to prepare titanium dioxide surface-modified with a hydroxyl group.

Example  1 and Comparative example  One

As raw material rubber, styrene-butadiene rubber (SBR 1500), titanium dioxide surface-modified with the hydroxyl group prepared in the preparation example, carbon black as a filler, stearic acid as a vulcanizing agent, zinc oxide, n-sulfur as a vulcanizing agent, and vulcanization accelerator Phosphorus t-butylbenzothiazolesulfenamide (tert butylbenzothiazolesulfenamide, TBBS) was mixed, melted and cured to have a composition as shown in Table 1 below to prepare a tire tread rubber specimen.

Test Example  One

The specimens prepared in Example 1 and Comparative Example 1 were pressed at 160 ° C. for 25 minutes using a hot press, and then made a plate having a thickness of 3 mm, and then measured for hardness, 300% modulus, tensile strength, and elongation according to ASTM-related regulations. The test was carried out, and the test results after UV aging for 3 days and 6 days are described in Table 2. Here, the hardness means the hardness, the higher the numerical value for tensile properties (300% modulus, tensile strength, elongation) means that the respective properties are excellent.

Looking at the test results of Table 2, Comparative Example 1, when UV aging occurs, the hardness is increased, 300% modulus, tensile strength, elongation all decreases drastically, Example 1 is all of the above physical properties constant UV It can be confirmed that aging is prevented.

In addition to improving the reinforcement of the surface-modified titanium dioxide rubber, wet road surface braking (Tanδ (0 ° C)) and rolling resistance (Tanδ (60 ° C)) are significantly improved.

Example  2 and Comparative example  2 to 6

To prepare a tire tread rubber specimens in the same manner as in Example 1, but to have a composition ratio as shown in Table 3, in Table 3 below, bis (3-triethoxysilpropyl) tetrasulfide as a coupling agent (TESPT, 50% TESPT available under the trade name X-50S. In Comparative Example 3-4, titanium dioxide was used as an anatase structure having an average surface diameter of 50 nm and a BET surface area of 100 m ² / g without surface modification.

Test Example  2

The physical properties of the rubber specimens prepared in Experimental Example 2 and Comparative Examples 2 to 6 were measured in the same manner as in Test Example 1, and the results are shown in Table 4 below. Here, Tanδ (0 ℃) is a value that can predict wet traction characteristics of the wet state of the tire performance, the higher the value means better, Tanδ (60 ℃) is a rolling resistance characteristic of the tire performance The lower the value, the better.

Comparative Example 2 and Comparative Example 3 has similar mechanical properties and dynamic properties, it can be seen that titanium dioxide does not significantly affect the physical properties.

Compared with Comparative Example 2 with titanium dioxide, Example 2 with surface modified titanium dioxide had a vulcanization rate of about 1 minute and 18 seconds, and 300% modulus and tensile strength increased by 17% and 10%, respectively. In addition, the wet road braking characteristics (0 ℃ tanδ) and rolling resistance (60 ℃ tanδ) are also improved by 25% and 3%, respectively.

When the surface modified titanium dioxide is applied, the vulcanization rate, physical properties, wet road surface properties, and rolling resistance properties are all excellent.

The tire tread rubber of the present invention including titanium dioxide surface-modified with such hydroxyl groups is not only excellent in UV anti-aging and wet road surface braking property, but also can improve reinforcement by adding a coupling agent. The tire tread rubber of the present invention is expected to be applied as a component of tires.

Claims (5)

  Raw rubbers containing one or more selected from natural and synthetic rubbers; Titanium dioxide surface-modified with hydroxyl groups; And Rubber for tires excellent in ultraviolet aging, wet road braking and reinforcement, characterized in that it comprises an additive or one or more selected from fillers, reinforcing agents and coupling agents. The method of claim 1, Rubber for tires having excellent ultraviolet aging, wet road braking and reinforcement, comprising 1 to 40 parts by weight of titanium dioxide surface-modified with hydroxyl based on 100 parts by weight of the raw material rubber. The method according to claim 1 or 2, The synthetic rubber is UV aging, wet road braking, characterized in that it comprises one or more selected from the diene polymer synthetic rubber, diene copolymer synthetic rubber, nitrile rubber, butyl rubber, urethane rubber and ethylene-propylene rubber And rubber for tires with excellent reinforcement. The method of claim 1, The coupling agent is bis (3-triethoxysilpropyl) tetrasulfide, bis (triethoxy silpropyl propyl sulfide, Bis (triethoxysilpropyl) monosulfide, bis (triethoxysil) ethane, bis (triethoxysil) hexane, bis (triethoxysil) decane and γ-mercaptopropyltriethoxysilane Rubber for tires excellent in ultraviolet aging, wet road braking and reinforcement, comprising 0.5 to 10 parts by weight of discontinuous or two or more kinds. To a solution of nitric acid and distilled water in a weight ratio of 1: 7 to 9, a titanium dioxide having an average diameter of 10 to 500 nm and a BET surface area of 10 to 200 m ² / g, anatase crystal structure, and then heated at a temperature of 90 ° C. or more A method for producing titanium dioxide surface-modified with a hydroxyl group, characterized in that the surface of the titanium dioxide is modified with a hydroxyl group.