JPS6221820B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for activating scrap vulcanizate. Scrap vulcanized rubber is generated in extremely large quantities from various rubber products such as automobile tires, bicycle tires, tubes, belts, etc., and to effectively recycle it, it is necessary to recycle it as a raw material for rubber and use it as a waste tire. This is becoming increasingly important from the standpoint of preventing pollution such as illegal dumping. The method of decomposing scrap vulcanized rubber and recovering and utilizing the generated carbon black, liquid and gaseous hydrocarbons, etc.
Although some methods have already been put into practical use, the technology for reusing scrap vulcanized rubber as a rubber raw material has not yet been put into practical use. That is, for the regeneration of scrap vulcanized rubber, a method of pressurizing and heating using, for example, acid, alkali or other chemicals has been used. However, these methods require a high-pressure heating device and have the disadvantage that the processing takes a long time. In addition, in order to crush scrap vulcanized rubber, there is a method of crushing waste rubber products such as scrap tires, removing metals and fibers, and then crushing it at room temperature or, recently, pulverizing it by low-temperature brittle destruction. is used. In particular, the latter, recycling technology for low-temperature frozen powder rubber, is an unexplored field, and the recycled vulcanized rubber powder itself has already aged to a considerable extent, and when it is recycled and used again to make rubber products. However, the current state of the art is that it can only be evaluated as a filler. The present invention solves all of the above-mentioned problems when recycling scrap vulcanized rubber, can be carried out industrially easily and in an extremely short time, and moreover, it can be recycled with almost the same quality as raw rubber. The present invention provides a method for activating scrap vulcanized rubber, which makes it possible to obtain recycled rubber. That is, the present invention provides scrap vulcanized rubber powder.
After adding and mixing 1 to 15 parts by weight of at least one selected from the group consisting of compounds having an OH group and/or COOH group and quinones to 100 parts by weight, the mixture is mixed without substantially causing decomposition of the rubber. The present invention relates to a method for activating scrap vulcanized rubber, which is characterized by irradiating high frequency waves. The method of the present invention includes automobile tires and tubes made of natural rubber or synthetic rubber such as SBR and NBR;
It can be applied to scrap vulcanized rubber for various rubber products such as bicycle tires, tubes, and belts, but it is most commonly used for automobile tires. In applying the method of the present invention, these scrap vulcanized rubbers are pulverized to remove metals and fibers by conventional methods and are made into powder. The viscosity of the powder is not particularly limited, but in order to perform the activation treatment in as short a time as possible, it is advantageous to have a particle size of 1 mm or less.
It is preferable that the particle size is such that it can pass through. The pulverization may be carried out by any conventional method, and the above-mentioned low-temperature freezing pulverization may also be used. To the scrap vulcanized rubber powder thus obtained,
At least one member selected from the group consisting of compounds having OH groups and/or COOH groups and quinones is added and mixed by any means such as spraying, scattering, or kneading. Various inorganic or organic compounds are used as compounds having OH groups and/or COOH groups and quinones, and inorganic substances include water, KOH,
Examples of organic substances include phenols, quinones, fatty acids, vegetable oils containing fatty acids (salad oil, tall oil, etc.), mineral oils (C heavy oil, etc.), and the like. Among these compounds,
Inorganic substances such as KOH and NaOH are usually about 0.1N to 0.5N
The organic substance is added to the scrap vulcanized rubber powder as an aqueous solution with a certain concentration. The amount of these compounds added is 0.1 to 15% by weight, more preferably about 0.2 to about 12% by weight, based on the scrap vulcanized rubber powder. If the amount added is less than 0.1%, the activation effect due to high frequency irradiation cannot be obtained sufficiently,
Even when the concentration exceeds 15%, no particularly significant increase in the activation effect is observed. Scrap vulcanized rubber and OH group and/or COOH
The conditions for irradiating a mixture with a compound having a group of 915 to 915 Hz vary somewhat depending on the type and particle size of the rubber to be treated, but care is taken not to substantially cause decomposition of the rubber to be treated. ~15000
Radio waves having a frequency of Hz, preferably about 915 to about 2450 Hz are irradiated for 3 to 5 minutes. Continuous irradiation for more than 5 minutes causes excessive decomposition of the rubber to be treated and smoke generation due to overheating, so if further irradiation is required, the above 3 to 5 minute irradiation is repeated at slight intervals. According to the present invention, by irradiating scrap vulcanized rubber with high frequency waves for a short period of time in the presence of compounds and/or quinones having an OH group and/or a COOH group, the scrap vulcanized rubber is sufficiently activated, and the raw material rubber is activated. Recycled rubber having substantially the same quality can be obtained. Although the mechanism of activation of scrap rubber according to the present invention has not yet been fully elucidated, high-frequency irradiation in the presence of the specific compound causes depolymerization or crosslinking of the scrap vulcanized rubber, and the surface of the rubber particles is It is presumed that this is based on improving the affinity and affinity with other polymeric substances by making them wet (wetting phenomenon) or fluidizing them. The present invention will be explained in more detail below by giving examples. Example Property composition of scrap vulcanized rubber Natural rubber + SBR (blend ratio 20:80) Polymer content 48.5% Acetone extract 17.2% Ash 4.6% Moisture 0.6% Specific gravity 1.15 Apparent specific gravity 0.33 Cord content Trace Iron content Trace Scrap vulcanization with the above properties Powder obtained by cryogenically freezing and pulverizing rubber (particle size: 100% passed through a wire mesh of 0.297 mm)
110 g of tall oil was added to 1000 g, and this was kneaded with a roll. The kneaded product was placed on a porcelain plate and subjected to high frequency irradiation at a frequency of 2450±50 MHz for 4 minutes to obtain an activated rubber. Rubber Powder Compounding Test Using the above activated rubber powder and non-activated rubber powder for comparison, each was blended with natural rubber and synthetic rubber in the proportions shown in Table 1, and the blends were kneaded with a roll.

[Table] Table 2 shows the results of measuring the physical properties of the vulcanized products obtained by vulcanizing the kneaded product samples having the formulations shown in Table 1 under the following vulcanization conditions. Vulcanization conditions (1) 141℃ 10 minutes (2) 141℃ 20 minutes (3) 141℃ 30 minutes The physical property test is based on JIS K.6301-1975 and JIS
Performed according to K.6300-1974.

[Table] From the results shown in Table 2 above, samples C, D, C' and D', in which the activated rubber powder obtained according to the present invention was blended with synthetic rubber or natural rubber, were blended with non-activated rubber. Corresponding samples A, B,
300% compared to A′ and B′ under the same vulcanization conditions.
It is recognized that all of the tensile stress, tensile strength and tear strength are excellent. In the above example, instead of tall oil,
When rubber powder activated using KOH (0.5N aqueous solution), salad oil, hydroquinone, and C heavy oil was used as a sample, the physical properties of the kneaded vulcanizate with natural rubber and synthetic rubber were measured, and the same results as above were obtained. .

Claims (1)

[Claims] 1. To 100 parts by weight of scrap vulcanized rubber powder,
At least one selected from the group consisting of compounds having an OH group and/or COOH group and quinones1
A method for activating scrap vulcanized rubber, which comprises adding and mixing up to 15 parts by weight and then irradiating high frequency waves without substantially causing decomposition of the rubber.