JPS586722B2 - How to recycle waste rubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for effectively recycling waste rubber such as waste tires.

In recent years, with the remarkable development of motorization, the amount of discarded used tires has also increased rapidly, and the disposal of them has become a problem.

Up until now, the main methods of disposing of waste tires have been reusing them in their original form, landfilling, and incineration.
It cannot be said that it meets social demands such as effective use of resources.

One way to meet these demands is to recycle waste rubber, which has been practiced for a long time, and this seems to be something that should be actively developed in the future.

In the past, various methods have been proposed for recycling waste rubber, but most of them require high temperatures of 150°C or higher and are difficult to implement unless someone has special equipment for that purpose. I couldn't.

Furthermore, most of the conventional recycling methods were developed for natural rubber, and rubber containing a large amount of synthetic rubber could not be effectively recycled.

The object of the present invention is to provide a new method for recycling waste rubber that overcomes these drawbacks.

The gist of the present invention is a method for recycling waste rubber, which comprises kneading waste rubber with oil and alkyl-substituted benzenesulfinic acid.

The method of the present invention has a lower processing temperature than other regeneration methods,
In addition, those who normally work in the rubber industry, such as rolls, can use the existing equipment as is.

Furthermore, according to the present invention, not only natural rubber but also waste rubber containing a large amount of synthetic rubber, which has been difficult to regenerate using conventional methods, can be effectively recycled.

Furthermore, the recycled rubber obtained by the method of the present invention exhibits superior performance than recycled rubber obtained by conventional methods.

The present invention will be explained in detail below.

The waste rubber that can be recycled in the present invention includes truck and bus tires in which natural rubber is mainly used, passenger car tires in which synthetic rubber is preferably used, and waste rubber such as belt hoses, sheets, and packing.

Of course, this also includes waste rubber generated during the molding of the above-mentioned articles.

These waste rubbers do not necessarily need to be powdered before being recycled, and any piece or sheet that is large enough to pass through the rolls may be used.

What are the alkyl-substituted benzenesulfinic acids used as regenerants? P-toluenesulfinic acid, O-toluenesulfinic acid, P-ethylbenzenesulfinic acid, O-ethylbenzenesulfinic acid, etc. benzenesulfinic acid with 1 carbon number
It includes those having 1 to 2 substitutions with about 4 to 4 alkyl groups.

Benzene sulfuric acid is equally effective.

Among these, P-toluenesulfinic acid is preferred.

It is preferable to use the alkyl-substituted benzenesulfuric acid in an amount that allows effective regeneration and does not inhibit the revulcanization reaction of the recycled rubber.

From this point of view, the ratio of 100 parts by weight of waste rubber is 0.1 to 1.
About 0 parts by weight is used.

Among these, effective regeneration is achieved within the range of 0.3 to 5 parts by weight.
A revulcanization reaction takes place.

In the present invention, the alkyl-substituted benzenesulfuric acid must be used together with oil.

When kneading with rubber, alkyl-substituted benzenesulfinic acid alone or oil alone does not cause plasticization, but it is extremely insufficient, and a significant effect is observed only when both are used together.

The oil that can be used in the present invention may be any softening oil or recycled oil used in the rubber industry.

For example, paraffinic, naphthenic, or aromatic process oils, high-boiling oils such as petroleum asphalt and coal tar, and vegetable oils such as tall oil, rosin, pine tar, and dipentene can be used.

The larger the amount of oil used, the more effective it is for regeneration.

However, since excessive use deteriorates the performance of the recycled rubber, it is usually used in an amount of 1 to 40 parts by weight, preferably 5 to 20 parts by weight, per 100 parts by weight of waste rubber.

Recycling of waste rubber is carried out by kneading the waste rubber with alkylbenzenesulfinic acid and oil on rolls.

Kneading can be carried out at a temperature of 150°C or lower,
It is better to work at a temperature of 100°C or lower, and the effect is greater.

The kneading time varies depending on the degree of plasticity required, but is usually
Sufficient plasticization can be achieved in 5 to 60 minutes.

Furthermore, by narrowing the gap between the rolls, the regeneration effect can be further improved.

Rubber recycled by the method of the present invention can be reused as a raw material for tires, belts, hoses, sheets, packing, etc., either alone or in combination with new rubber.

The present invention will be explained in more detail with reference to Examples below.

In the examples, the plasticity used as an index of the degree of regeneration was measured using a Rapid Plastymeter manufactured by Wallace at a temperature of 100°C and a load of 12.7 kg/cm.
Measured under r2 conditions.

The smaller this value is, the greater the plasticity is, and a value of 70 or less is practically desired.

The parts in the blending ratio are parts by weight.

Example 1 100 parts by weight of 30 mesh powder rubber (about 70% natural rubber, about 20% styrene-ptadiene rubber, about 10% butadiene rubber) obtained from waste passenger car tires was added to 1 part by weight in a suitable container. of P-toluenesulfinic acid and 10 parts by weight of process oil.

This mixture was transferred onto a roll with a narrow gap and passed through repeatedly, and the powdered rubber immediately became a sheet.

Although this sheet initially had poor plasticity and still retained elasticity, its plasticity rapidly increased during continued kneading.

After 30 minutes, the rubber sheet was collected from the roll.

During this time, the roll temperature was maintained at 40 to 60°C.

The plasticity of the rubber sheet thus obtained was 53, indicating that the regeneration was effective.

Example 2 Except that 3 parts of P-}luenesulfinic acid were used.
The same treatment as in Example 1 was performed.

The plasticity in this case was 45, and an even greater effect was obtained.

Comparative Examples 1 and 2 The same treatments as in Example 1 were carried out using 100 parts of the powdered rubber used in Example 1 and 3 parts of P-toluenesulfinic acid, and 100 parts of the powdered rubber and 10 parts of process oil. .

The plasticity in this case is 93 and 73, respectively, and when used alone, the value when both are used together is 45.
I understand that it is not as good as .

Examples 3 and 4 Rubber scraps from waste truck and bus tires (mainly natural rubber)
The same treatment as in Example 1 was carried out using a vulcanized rubber having a size of 1 to 2 mm% and a 2 mm square vulcanized rubber made of styrene-butadiene rubber.

However, for rubber made only of styrene-butadiene rubber,
15 parts of process oil was used, and the kneading time was also 60 minutes.

Next, these recycled rubbers were compounded and vulcanized according to the method of JIS K6313 to prepare a slap sheet with a thickness of 2 mm, and the hardness (JIS), strength at break, and elongation at break were measured.

These physical property values and plasticity upon regeneration are summarized and listed in Table 1 below.

Comparative Example 3 For comparison, commercially available recycled rubber from waste truck and bus tires was also compounded and vulcanized according to the JIS K6313 process, and its physical properties are listed in Table 1.

In Table 1, it is clear that the vulcanized physical properties of rubber recycled from waste truck and bus tires by the method of the present invention are superior to the vulcanized physical properties of commercially available recycled rubber from tires of the same type.

Furthermore, Example 4 shows that the method of the present invention is also effective for recycling rubber made only of synthetic rubber.

Claims (1)

[Scope of Claims] 1. A method for recycling waste rubber, which comprises kneading waste rubber with tea oil and alkyl-substituted benzenesulfinic acid. 2. The method for recycling waste rubber according to claim 1, wherein the amount of the alkyl-substituted benzenesulfinic acid is 0.1 to 10 parts by weight per 100 parts by weight of the waste rubber. 3. The method for recycling waste rubber according to claim 2, wherein the amount of the alkyl-substituted benzenesulfinic acid is 0.3 to 5 parts by weight. 4. The method for recycling waste rubber according to claim 1, wherein the alkyl-substituted benzenesulfinic acid is P-toluenesulfinic acid. 5 The blending amount of the oil is 1 to 1 per 100 parts by weight of the waste rubber.
40 parts by weight of the method for recycling waste rubber according to claim 1. 6. The method for recycling waste rubber according to claim 5, wherein the amount of the oil is 5 to 20 parts by weight. 7. The waste rubber recycling method according to claim 1, wherein the kneading method is roll kneading. 8. The method for recycling waste rubber according to claim 1, wherein the kneading temperature is 150° C. or lower. 9. The method for recycling waste rubber according to claim 8, wherein the kneading temperature is 100°C or less.