KR100932973B1 - Rubber composition for tires using photocatalyst coating - Google Patents

Abstract

The present invention relates to a rubber composition for tires using a photocatalyst coating, wherein the rubber composition for tires using a photocatalyst coating is a rubber compound comprising a raw material rubber and a filler and an ammonium phosphate salt as a titanium oxide and a dispersion stabilizer as a photocatalyst. And a photocatalyst dispersion comprising polyvinyl alcohol as a crosslinking agent.

According to the rubber composition for a tire using the photocatalyst coating of the present invention, the appearance of the tire can be maintained, that is, the blackness can be continuously maintained, thereby maintaining the gloss of the first production as it is, and at the same time, in the rubber composition by preventing aging of the rubber. Minimize the use of antioxidants.

Tire * Photocatalyst * Coating * Anti-Aging

Description

Rubber composition for tire using photocatalyst coating

The present invention relates to a rubber composition for a tire, and more particularly, to a rubber composition for a tire using a photocatalyst coating which can maintain the gloss of the tire produced as the first using a photocatalytic coating technique and greatly improve appearance quality. will be.

Among the components of the tire, the tread part and the sidewall part are so-called exterior appearances that are constantly outside even after being mounted on the wheel. In particular, according to the recent consumer trend, the appearance is more important in the purchase or price of tires.

However, the tire rubber material of the tread part and the sidewall part actually contains a large number of chemicals. In particular, the anti-aging agent, which is added to prevent the aging of the rubber, literally moves to the rubber surface in order to prevent the aging of the rubber. Should act to prevent the aging of rubber by oxygen or ozone. These antioxidants are responsible for the browning action that changes the color of the tread or sidewall to brown.

In the real tire industry, there are cases where a new anti-aging agent is basically introduced to solve this problem, but inevitably, the blackness of the tire is reduced when it moves to the surface and comes into contact with the atmosphere. Moreover, these anti-aging agents are also undesirable in terms of price competitiveness.

On the other hand, the prior art for overcoming such a problem is disclosed, for example, in the Republic of Korea Patent Publication No. 2007-59150, there is a method for surface coating on the appearance of the tire and such surface coating method is generally silicone graft acrylic resin It is made to dissolve in a solvent so that a uniform film is formed, and it gives gloss to the flexible and elastic surface of a tire, and prevents stickiness and adhesion of contaminants.

However, the above-described prior art has no ultimate sustainability because it is easily cleaned by rain water when the tire is actually mounted and used.

The present invention was created to solve the above problems, by developing a photocatalyst coating technology for tire coating to remove the harmful substances in the interior and exterior of the building to maintain the blackness of the tire continuously, To provide a rubber composition for a tire using a photocatalyst coating that can maintain the glossiness of the first product produced as it is.

Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. Furthermore, the objects and advantages of the present invention can be realized by means and combinations indicated in the claims.

The rubber composition for tires using the photocatalyst coating according to the present invention comprises a rubber compound comprising a raw material rubber and a filler, a photocatalyst dispersion comprising titanium oxide as a photocatalyst, ammonium phosphate salt as a dispersion stabilizer, and polyvinyl alcohol as a crosslinking agent.

The rubber compounding agent may include a raw material rubber that can be commonly used in the tread portion and the side wall portion, and carbon black or silica as a filler and other additives such as zinc oxide, stearic acid, process oil and the like.

Photocatalyst coating technology is a technique that is commonly practiced for removing harmful substances in building interior and exterior agents, but in the present invention, such a technology was developed for tire coating to achieve an improved appearance of tires.

On the other hand, the photocatalyst technique is briefly described, and when light is irradiated to particles having semiconductor properties, electrons having a strong reducing action and holes having a strong oxidation action are generated, and the molecular species in contact with the semiconductor are redoxed. Decompose by action. This action is called a photocatalytic action, and by using the photocatalytic action, it is possible to decompose and harmless the surrounding organic matters.

Therefore, a substance exhibiting a photocatalytic action, that is, a photocatalyst has recently begun to be used for various purposes such as, for example, water treatment, deodorization, exhaust gas treatment, atmospheric purification, and soil treatment.

The photocatalyst dispersion includes a photocatalyst, a dispersion stabilizer, and a crosslinking agent.

The photocatalyst in the present invention may be a powder containing a component exhibiting photocatalytic activity. For example, one or two or more oxides, nitrides, sulfides, and the like of a metal element such as Ti, Zr, Hf, V, and Nb may be used. include a powder as an ingredient, and it is preferable to use the general-purpose and put to practical use a titanium oxide (TiO _2).

On the other hand, in order to put a photocatalyst such as titanium oxide into practical use, it is necessary to fix the photocatalyst to a substrate or the like. For example, the photocatalyst is dispersed in a liquid medium and applied to a substrate or the like in the form of a dispersion.

In the case of producing such a photocatalyst dispersion, when the corrosiveness or the danger to the human body becomes a problem, a dispersion having a pH of a neutral region which is not acidic or alkaline is considered to be preferable, but the photocatalyst particles are difficult to disperse in the neutral region. .

In order to overcome this problem, the present invention contains an ammonium phosphate salt as a dispersion stabilizer and at the same time includes a hydrophilic polyvinyl alcohol (hereinafter referred to as 'PVA') resin as a crosslinking agent.

The ammonium phosphate salt is included in an amount of 5 to 20 parts by weight based on 100 parts by weight of the photocatalyst. If the content is less than 5 parts by weight, the dispersion stability effect is insignificant, and when used in excess of 20 parts by weight, the photocatalytic activity of the coating film obtained using the dispersion. This lowers or raises the viscosity of the dispersion during storage.

The PVA resin as the crosslinking agent enables the uniform coating film formation between the photocatalyst particles and at the same time enables the long term storage, and the content of the PVA resin is 5 to 10 parts by weight based on 100 parts by weight of the photocatalyst. desirable.

By incorporating the PVA resin as described above in the photocatalyst dispersion, there is an advantage in that the rubber aging can be suppressed as a result, thereby preventing an accident due to the growth of the fine cracks on the surface in advance.

In addition, since the photocatalyst dispersion is contained in the tire rubber composition, a sufficient anti-aging effect can be obtained without using a predetermined amount or a total amount of anti-aging agent, and thus, it is expected to contribute greatly to cost reduction and environmental pollution of the compound.

On the other hand, the photocatalyst dispersion according to the present invention preferably maintains the pH at a level of 6.5 to 7.5, so that the rubber surface of the tire is not damaged when it is within the above range.

The terms or words used in this specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best describe their invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

The rubber composition for a tire using the photocatalyst coating according to the present invention provides the following effects.

The improvement of the appearance of the tire, that is, the blackness can be maintained continuously to maintain the gloss of the first production as it is, and at the same time it can minimize the use of the anti-aging agent in the rubber composition by preventing the aging of the rubber.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but it should be noted that the present invention is not limited by the following examples.

The composition of the photocatalyst dispersion is shown in [Table 1] and the sidewall rubber compounding agents are shown in [Table 2].

Sidewall Rubber Composition

In the following Examples and Comparative Examples, the sidewall rubber compounding agent of the tire manufactured in common is a raw material rubber consisting of 60 parts by weight of natural rubber and 40 parts by weight of synthetic rubber, 50 parts by weight of carbon black, 3.0 parts by weight of zinc oxide, and stearic acid 2.0. Parts by weight, 5.0 parts by weight of oil, 3.0 parts by weight of adhesive and 1.5 / 0.8 parts by weight of sulfur / promoter.

Example  And Comparative example

<Example 1>

Aqueous ammonium phosphate solution was prepared at 0.53 wt% based on the ion exchanged water, and 0.53 wt% of the PVA resin was added to the prepared ammonium phosphate aqueous solution based on the total content of ammonium phosphate, ion exchanged water, and PVA as shown in Table 1 below. By dissolving sufficiently, an ammonium phosphate / PVA aqueous solution was prepared. Next, a titanium oxide dry powder having a BET surface area of 15.0 to 30.0 m 2 / g in an aqueous solution of ammonium phosphate / PVA was added in an amount of 5 wt% based on the total content of ammonium phosphate, ion-exchanged water, PVA and titanium oxide, as shown in Table 1 below. The content was placed in a stirring disperser, and zirconia beads having a diameter of 0.2 mm were used as the dispersion medium, and mixed at 1000 rpm for 1 hour. As a result, a titanium oxide photocatalyst dispersion having an average particle diameter of 200 nm was prepared. The dispersion was centrifuged at 1500 rpm for 20 minutes to remove granulated powder, to obtain a photocatalyst dispersion having a solid content of 10 wt%, which was diluted with ion-exchanged water to give a final solid content of 5 wt%. In this case, the solid content concentration means a concentration including titanium oxide and PVA prepared as a dispersion. The photocatalyst dispersion prepared as described above is sprayed onto a tire containing 6 parts by weight of an anti-aging agent.

<Example 2>

The same procedure as in Example 1 was conducted except that the PVA resin was changed to 0.26 wt%.

<Example 3>

Example 3 was carried out in the same manner as in Example 2, except that the antioxidant was completely removed from the sidewall compound of the tire to be coated.

Comparative Example 1

It was prepared in the same manner as in Example 1 except that the photocatalyst was easily dispersed to have an acidic pH using an aqueous solution of nitrate without using ammonium phosphate salt and using a polymerizable silicon compound which is commonly used without using PVA. It was carried out by the method.

Comparative Example 2

The same procedure as in Example 1 was carried out except that a polymerizable silicon compound was used without using PVA.

Comparative Example 3

Comparative Example 3 was carried out in the same manner as in Example 3, except that the photocatalyst coating was not performed.

<Comparative Example 4>

Comparative Example 4 was carried out in the same manner as in Comparative Example 2 except that no antioxidant was used.

Unit: parts by weight Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4   Photocatalyst Dispersion Composition Ion exchange water 1880 1880 1880 1880 1880   No photocatalytic coating 1880 Ammonium Phosphate 10 10 10 - 10 10 nitric acid - - - 10 - - PVA 10 5 5 - - - Polymerizable Silicon Compound - - - 10 10 10 Titanium Oxide ⁽¹⁾ 100 100 100 100 100 100

Corporation

(1): BET surface area is 15.0-30.0 m <2> / g, and average particle diameter is 200 nm.

Sidewall Rubber Compounding Unit: parts by weight Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4  Configuration Common application Natural rubber / synthetic rubber: 60/40, carbon black: 50 zinc oxide: 3.0, stearic acid: 2.0, oil: 5.0 adhesive: 3.0, sulfur / accelerator: 1.5 / 0.8  Anti aging agents 6PPD 3.0 3.0 - 3.0 3.0 - - RD 1.0 1.0 - 1.0 1.0 - - Wax 1.0 1.0 - 1.0 1.0 - -

Performance evaluation of the Examples and Comparative Examples is shown in Table 3 below.

Performance evaluation Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Luster ◎ ◎ ◎ △ ○ X ○ Surface contamination after driving ○ ○ ◎ X X X X Rubber Aging Rate (%) 19 21 35 48 39 78 56

Glossiness: Evaluation after 3 months after tire manufacturing (◎: Very good, ○: Good, △: Normal, X: Poor)

Surface contamination after running: Evaluation after 6 months after tire running (◎: Very good, ○: Good, △: Normal, X: Poor)

Rubber aging rate: tires are collected one year after driving, and the aging property is evaluated to evaluate the aging rate.

The tire coated with the photocatalyst dispersion according to Example 1 did not change at all after 3 months of appearance gloss, and was superior to the tire without the photocatalytic coating even after the vehicle was actually mounted on the vehicle. As a result of evaluating the degree of aging of the rubber physical properties, the aging rate was 19%, showing a significantly improved result compared to Comparative Example 1.

In addition, in Example 1, the pH of the photocatalyst dispersion was 6.7, so that the risk of corrosion and damage to the tire surface could be prevented.

It can be seen that the physical properties of Example 2 also show the same level as in Example 1, in the case of Example 3, the appearance of the gloss of the same excellent gloss as the tires of Examples 1 and 2 to which the anti-aging agent was applied after 3 months The surface contamination after running was much better than that of Examples 1 and 2 in non-pollution.

On the other hand, in the aging rate, Example 3 was found to be somewhat lower than in Examples 1 and 2, but showed an improved result compared to the comparative example and compared to Comparative Examples 3 and 4 in particular not using the same anti-aging agent Showed greatly improved results.

In addition, the pH of the photocatalyst dispersion of Comparative Example 1 was 2.5, and the glossiness of the appearance was maintained at a normal level, and the degree of surface contamination and the aging rate after running were significantly lower than those of the examples.

In addition, Comparative Example 2 showed a relatively good gloss compared to Comparative Example 1, but the surface contamination degree and aging rate after running showed the same results as Comparative Example 1.

Comparative Example 3 is basically a result of not applying the photocatalyst coating showed that the glossiness after 3 months showed a significantly worse level, the same after driving. The compound's aging rate was the lowest at 78%.

In Comparative Example 4, the glossiness was good, but the surface contamination degree after running was also largely different from the examples of the present invention, and thus appeared to be greatly contaminated. Seemed.

Through the above results, it can be seen that the photocatalyst dispersion containing ammonium phosphate salt, PVA, and titanium oxide prevents contamination of the tire surface and greatly improves the appearance performance.

In addition, even by limiting or excluding the use of the anti-aging agent can maintain the same level of physical properties there is an advantage that can contribute to cost reduction and environmental pollution of the compound.

Claims (4)

Rubber compounding agent including raw rubber and filler; And A photocatalyst dispersion comprising titanium oxide as a photocatalyst and ammonium phosphate salt as a dispersion stabilizer and polyvinyl alcohol as a crosslinking agent, The photocatalyst dispersion is a rubber composition for a tire using a photocatalytic coating comprising 5 to 20 parts by weight of ammonium phosphate salt and 5 to 10 parts by weight of polyvinyl alcohol based on 100 parts by weight of titanium oxide. delete The method of claim 1, The photocatalyst dispersion is a rubber composition for a tire using a photocatalyst coating, characterized in that the pH is maintained at 6.5 to 7.5. The method of claim 1, The rubber composition is a rubber composition for a tire using a photocatalyst coating, characterized in that it does not contain an antioxidant.