KR20040102839A - The rubber compounds for tire sidewall - Google Patents

Abstract

PURPOSE: A rubber composition for tire sidewall is provided to prevent soiling of tire, thereby improving the appearance and antiaging properties of the resulted tire, with reducing the use of an antiaging agent such as 6PPD. CONSTITUTION: The rubber composition for tire side wall comprises N-(1,3-dimethylbutyl)-N'-phenyl-para-phenylenediamine(6PPD) and TMDQ (Polymerized 2,2,4-trimethyl-1,2-dihydroquinoline) and wax, each of which is used as the same amount, ranged between 1-3phr, based on 100phr of rubber. The wax comprises 10-50% micro-type wax, and has the molecular weight distribution of carbons of 20-45, wherein the maximum molecular weight distribution of carbons includes broad and/or two peaks in the range of 26-35.

Description

Rubber composition for tire sidewalls

The present invention relates to a rubber composition for tire sidewalls, and more particularly to avoiding the maximum carbon molecular weight biased to medium temperature in the rubber composition for tire sidewalls, the maximum carbon molecular weight distribution having a wide distribution at 26 to 35 or having two peaks. (26 ~ 27, 34 ~ 35) If you use wax, you can adjust blooming at medium temperature, improve the appearance pollution, reduce 6PPD anti-aging agent which promotes the movement of wax, and apply TMDQ to improve the appearance improvement It relates to a rubber composition for sidewalls.

The amount of the preservative 6PPD having excellent ozone aging resistance functions to promote the movement of the wax proportionally. In addition, by the experiment, the ozone anti-aging agent plays a role of improving the mutual function together with the heat-resistant anti-aging agent. Therefore, the aging resistance is improved by reducing the content of 6PPD, controlling the content of TMDQ and wax, and controlling the maximum carbon molecular weight distribution of the wax.

Waxes used in tires are classified into low temperature (about 0 ° C), medium temperature (about 20 ~ 30 ° C), or high temperature (about 40 ° C or more), and are usually used for medium temperature, or medium and high temperature. Our company manufactures and uses the 1: 1 mixture of medium temperature and high temperature. However, in the case of using such a wax, sometimes excessive wax is surface-shifted in the storage temperature range, causing appearance contamination. This is because the maximum carbon molecular weight (31 or 33) of the wax is for the medium temperature range. Since the required temperature condition of the wax is in the medium temperature range, the surface movement is particularly good, while the excessive movement of the wax may cause surface contamination. However, when the maximum carbon molecular weight distribution has a wide distribution or two waxes (with double peaks at 26 to 27 and 34 to 35), blooming can be controlled at medium temperature and excellent ozone aging resistance. Was evaluated.

When the wax is incorporated into the rubber, it acts as an internal lubricant of the rubber to shorten the kneading time and to help disperse the filler. In addition, the rubber has a function to prevent the aging phenomenon that the crack is caused by light and ozone action in the air.

Since the wax is blended with rubber and moves over time from the inside of the rubber to the rubber surface, the ozone reaction is prevented from starting. This phenomenon is influenced by the properties of the wax itself, the content of rubber compounding, and the time and temperature before and after the foot exposure. In addition, the wax properties required to achieve the lubrication effect include 1) rapid formation of a film (adequate transition speed depending on temperature) 2) formation of a good surface film (cohesiveness, plasticity, adhesion), and 3) direct effect. The wax is a mixture of linear, branched, cyclic hydrocarbons, etc., and the complexity determines the protective coating properties peculiar to the wax based on the solubility of the wax in rubber and mobility in the rubber.

This rise and fall of temperature is relative to the melting point of the wax. In the relationship between the melting point of the wax, that is, the molecular weight and the solubility-mobility, the paraffin wax shows the maximum value, whereas the high melting point microwax shows a larger molecule and a more complicated molecular structure than the paraffin wax, resulting in poor mobility. At the same time, the melting point gradually decreases. Paraffin wax is faster at 40 ° C than 40 ° C, and in the case of microwax, the reverse tendency is observed.

Therefore, if the effect is to be obtained over a wide temperature range, the mixed use of both is recommended.

The amount of blooming is related to the solubility and mobility of the wax. When the wax remains above the solubility in rubber, continuous blooming occurs and the bloom is terminated after equilibrium is reached. As the temperature rises, the solubility of the wax naturally increases, and the wax on the rubber surface is dissolved again and disappeared. In order to increase the amount of wax blooming, the temperature is adjusted to low temperature.

The most effective wax is about 0.5 μm at 25pphm ozone concentration. When the quality of the wax is deteriorated, an incomplete film is easily formed on the surface of the rubber, and the micro parts generated by the incomplete film are subjected to a concentrated attack of ozone, which is a small number, but is more likely to cause large and severe cracking than the rubber surface without the wax.

In order to preserve the rubber surface for a long time, it should not be influenced by climate change, abrasion damage and loss while maintaining the required film thickness during that time.

The rate of blooming and recovery rate of the break coating depends on the mobility and solubility of the wax in the rubber, as mentioned earlier. Generally, melting | fusing point of a wax is 50-75 degreeC. Wax below this melting point increases mobility, but solubility increases, and above 75 ° C. is because the bloom rate decreases and it does not form a film necessary before cracking starts.

In spite of the function of the wax, the shape of the wax transferred to the surface is incomplete and the film does not form a stable film, and even the appearance of contamination on the tire surface is caused.

An object of the present invention is to improve the aging resistance and to reduce the appearance contamination by the wax by adjusting the anti-aging system with the wax used in the tire sidewall rubber composition to solve the problems of the prior art as described above.

In order to achieve the above object, the rubber composition for a tire sidewall of the present invention contains the same amount of 6PPD, TMDQ, and wax, respectively, and the content is added 1 to 3phr.

In the present invention, the wax has a carbon molecular weight distribution in the range of 20 to 45, contains 10 to 50% of the microtype wax, and has a maximum and / or two peaks at a maximum carbon molecular weight distribution of 26 to 35. .

The present invention will be described in more detail with reference to the following examples.

Table 1 is a table showing the amount of wax movement according to the concentration of 6PPD.

Referring to Table 1, it can be seen that as the concentration of 6PPD increases, the amount of wax movement increases with time.

Table 1 Relationship between 6PPD concentration and wax migration

Wax Bloom, ㎍ / ㎠

density Early 1 week 3 weeks 6 Weeks 6PPD = 0 15 15 15 15 6PPD = 1 15 15 18 17 6PPD = 3 15 23 25 27

Table 2 shows the ozone resistance of the tire when the amount of wax is fixed after fixing the amount of wax in the static state or the amount of wax is fixed after fixing the amount of 6PPD.

Referring to Table 2, when the concentration of 6PPD is fixed and the amount of wax is increased, ozone resistance is significantly increased.However, when the amount of wax is fixed and the amount of 6PPD is increased, the concentration of 6PPD is fixed and the amount of wax is increased. The increase in ozone resistance was small compared to the increase.

Table 2) Evaluation result of ozone resistance in static state

Anti-aging Wax 0 One 3 5 0 0 0 6PPD 0 0 0 0 One 2 3 Ozone resistance duration 25 25 > 210 > 210 25 60 77

Table 3 is a table showing the dynamic fatigue life of the tire when changing the amount of 6PPD after fixing the amount of wax in the dynamic state or the amount of wax after fixing the amount of 6PPD.

Referring to Table 3, the ozone resistance was decreased when the concentration of 6PPD was fixed and the amount of wax was increased in the dynamic state, but the ozone resistance was increased when the amount of the wax was fixed and the amount of 6PPD was increased.

Table 3) Dynamic Fatigue Life

Anti-aging Wax 0 5 5 0 One 6PPD 0 0 One 3 3 Ozone resistance duration 95 72 105 160 130

Table 4 is a table showing the change in physical properties when the road system of the rubber composition of the tire sidewall is changed.

Hereinafter, the present invention will be described by the following comparative examples, examples and test examples. However, these do not limit the technical scope of the present invention.

Comparative Example 1

Wax, 6PPD, wax are not included and the same as usual PCR T / D comp'd.

Comparative Example 2

It is the same as a conventional PCR T / D comp'd except that it contains 2 µg / cm 2 of wax.

Comparative Example 3

It is the same as a conventional PCR T / D comp'd except that it contains 2 µg / cm 2 of wax and 4 µg / cm 2 of 6PPD.

<Example 1>

It is the same as normal PCR T / D comp'd except including wax 2 microgram / cm <2>, 6PPD 4 microgram / cm <2>, and TMDQ 2 microgram / cm <2>.

The content of wax, 6PPD, and TMDQ is different compared to Comparative Example 1, the content of 6PPD and TMDQ is different compared to Comparative Example 2, and the content of 6PPD and TMDQ is different compared to Comparative Example 3.

Table 4) Relationship between the changes in the labor protection system

* Change only the fire protection system to normal PCR T / D comp'd

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Changes in the defense system (others identical) Wax 0 2 2 2 6PPD Barrier 0 0 4 3 TMDQ 0 0 0 2 Vulcanization Characteristics TOQ (max) 36.3 35.2 32.3 31.9 TOQ (minimum) 12.4 10.6 10 10 T40 6.81 7.08 6.13 6.27 T90 10.15 10.81 9.74 10 EC 11.16 11.89 10.71 11 Initial tensile property HARD'S 58 58 57 58 M-300% 83.4 90 76.9 80.8 T.S. 232.8 218.2 217.9 221.8 E.B. 604.1 558.1 604.2 604.8 Tensile Properties after Aging A-HARD'S 64 65 64 65 A-M-300% 134.3 135.3 118.9 119.9 A- T.S. 179.4 162.2 185.3 182.8 A- E.B. 382.3 348.4 434.4 428.1 Thermal Aging Characteristics After thermal aging Retention rate 77 74 85 82

Optimal road system improvement can prevent tire pollution and improve aging resistance.

Claims (2)

Rubber composition for tire sidewalls comprising N- (1.3-dimethybutyl) -N'-phenyl-para-phenylenediamine (6PPD) and TMDQ (Polymerized 2,2,4-trimethyl-1,2) for 100 phr of rubber -dihydroquinoline) and the content of the wax, each containing the same amount, the content is 1 to 3phr rubber composition for the tire sidewall, characterized in that the addition. The wax of claim 1 wherein the wax has a carbon molecular weight distribution in the range of 20-45, comprises 10-50% of microtype wax, and has a maximum carbon molecular weight distribution of 26-35 wide and / or two. It has a peak, The rubber composition for tire side walls.