SU538001A1 - The method of processing crumb synthetic rubber - Google Patents

Description

(54) METHOD FOR TREATING A SYNTHETIC CRUM

RUBBER

one

The invention relates to the production of rubbers in the form of free-flowing non-adherent particles during storage.

The use of rubbers in the form of crumbs or powder, non-sticky during storage and

transportation, in rubber processing and other sectors of the industry allows to significantly intensify and automate the processes of manufacturing rubber compounds, improve the quality of products.

A known method of treating rubber crumbs obtained by mechanical measurement with powders such as talc, chalk, kaolin, starch, magnesite, zinc stearate, and mixtures thereof ll.

There is also known a method of treating crumbs of styrene-butadiene rubber, obtained in the form of particles 1.5–25 mm in size by mechanical grinding of rubber blocks with simultaneous feeding of vinylaromatic resins —lopsigirol, popivinilopuopa, polychlorostyrene, etc. into the grinder. F2j. The resulting rubber crumb does not stick together during storage and is used to intensify the process of dissolving rubber in styrene, followed by graft polymerization. The disadvantages of this method include agglomeration of rubber particles under conditions of long-term storage, the production of rubber chips by mechanical grinding of rubber blocks, which is associated with high energy costs and deterioration of the physical and mechanical properties of vulcanizates.

The purpose of the invention is to reduce the stickiness of rubber crumbs during long-term storage and to improve the strength properties of the vulcanizate.

According to the proposed method, wet rubber crumb obtained in the process of isolating rubbers from latex or polymer solution is treated with vinyl aromatic resins made in the form of fine powder in an amount of 20-80 parts by weight per 1OO in the polymerization process with monomers with two or three vinyl groups. weight, rubber crumb. The pulp produced in the rubber separation process is fed to a sieve, where a drum or other type mixer is separated from the water and sent directly to the B, an excess of powder of a structured vinyl aromatic resin is fed to the sieve, after the crumbing of the rubber crumb, the excess powder is separated on the sieve, and baby post goes to the air dryer. Free flowing, non-sticky rubber particles are obtained. The amount of resin remaining on the rubber surface is 2-10%. The proposed method makes it possible to obtain almost all types of rubbers in the form of a crumb that does not stick together under rather harsh storage conditions, apparently due to the specific properties of the structured polymer. Copolymers of styrene, vinyl toluene, chlorostyrene and other monomers with polyfunctional structuring monomers containing two or more vinyl groups, such as divinyl benzene, diisopropenyl benzene, trimethacrylate, triethanolamine can be used as structured vinyl aromatic resins. Ternary copolymers of the indicated monomers with acrylo-nitrile, oC-methyl-tyrol can also be used. methyl methacrylate, etc. The resins are obtained by radical polymerization in an emulsion, followed by coagulation of the latexes, washing the mineral from the salt: and drying under mild conditions that exclude agglomeration (coalescence) of the powder. The most effective powders with a particle size of 0.05-0.2 mm. The test of rubber crumb for stickiness during storage is carried out by holding it under constant pressure in a plunger form for 4-7 days. The specific pressure on the crumb is from 100 to 4OO GS / cm, which corresponds to the storage time of rubber crumbs for 8-12 months in the lower row of a 1.2 m high pile. Example 1. In a Yul vessel equipped with a propeller agitator, 143 O ml of SCS-ZOARK low temperature styrene-butadiene rubber latex (dry content 20.9% emulsifier – potassium soap mixture of rosin and synthetic fatty acids in a 4: 1 ratio, Mooney rubber viscosity - 38%) is poured; 2250 ml of its valuable chlorine solution In addition, sodium is added and then 1% sulfuric acid is added to a pH of 3-4. The resulting pulp is washed with water, the water is separated on a sieve, and a wet crumb with particles of 1-3 mm in size (see Table 1) is placed in a rotating drum, where gradually within 3-5 minutes powder of a copolymer of styrene, acrylonitrile and divinylbenzoa is obtained, obtained with a monomer ratio of 79: 20: 1 corresponding to 7x: in an amount of 12O g. After 10 minutes of processing the rubber crumb, the contents of the drum are unloaded onto a sieve and by shaking separates the excess powder from the crumb. The amount of powdered gum remaining on the rubber crumb is 6.7%. Powdered crumb is dried in an air dryer at a temperature of 90 ° C. The crumb is tested for adhesion, a standard rubber compound is prepared and the vulcanisate is prepared. The test results are shown in Table. 2. Example 2. 480 ml of latex low-temperature butyenestyrene rubber SKS-ZORKP (dry content 20.9%, emulsifier - a mixture of potassium rosin rosin and synthetic fatty acids in the ratio of 4: 1, Mooney viscosity 38) and fl ochuliruyut his introduction of 6 O ml of a saturated solution of sodium chloride. 15 g of highly aromatic oil PN-6K heated to 70 ° C are introduced into phpocule and complete the coagulation by introducing into the apparatus a mixture of 25 O ml of a saturated solution of sodium chloride with 1000 ml of 1% sulfuric acid solution. A slurry of SKS-ZOARKM-15 oil-filled rubber with an average size of 1-5 mm crumb is obtained. The crumb is washed, the water is separated on a sieve and placed in a rotating drum, where gradually within 3-5 minutes 4O g of styrene copolymer powder, ° C-methylstyrene powder and diisopropenylbenzene obtained at a ratio of monomers of 65: 30: 5, respectively, are supplied. The particle size of the dusting material is less than 0.1 mm (see Table 3). At the end of the rubber crumb treatment, the contents of the drum are placed on a sieve, and the excess powder is removed by shaking. The crumb containing 8.7% resin is dried in an air drier at a temperature of 9 ° C. The resulting crumb is tested for stickiness and a standard rubber compound is prepared and vulcanized. The test results are shown in Table. 2, Example 3. In the vessel according to Example 1, 11OO ml of butadiene nitrite latex, SKN-4OM rubber (emulsifier-nekal, Defo rubber hardness 950 gs, dry matter content 13.6%) is poured and 454O ml of 5% is coagulated sodium chloride solution. The resulting crumb from a particle size of 2-5 mm (see Table 1) is passed through a hammer type crusher, while simultaneously feeding 60 g of styrene-trimethyl methacrylate triethanolamine copolymer powder obtained at a ratio of 95: 5 monomers, respectively.

The particle size of the dusting material is given in Table 3. On the sieve, shaking off the excess powder and chips, containing 4.3% of the dusting material, dried in an air dryer at a temperature of 8 ° C. A rubber crumb is obtained which does not stick together during storage, the test results of which are given in Table. 2. In parallel, test the crumb SKN-40M rubber, treated with polystyrene powder according to US patent No. 2895939.

The test results are shown in Table. four.

Example 4. A thermostated 10 liter cylindrical vessel equipped with a stirrer containing 8 liters of water at a temperature of 95-98 ° C is introduced in small portions of 1 liter of a 10% aqueous solution of butikabuchuka brand BK-1675T in isopentone. The resulting crumb with particles of 1.5-4 mm in size is washed, separated on a sieve from water, and fed to a hammer type crusher, at the same time entering 80 g of powder into it.

Fractional composition of rubber crumb

five

5 3 2 1

copolymer of styrene and divinylbenzene obtained with a monomer ratio of 90: 1 and, respectively. The crumb separated on a sieve from the shaking of the powder by shaking is dried in an air drier at a temperature of 90 ° C. A rubber crumb is obtained that does not stick together during storage, containing 7.2% of dusting material, the test results of which are given in Table. 2. In parallel, a crumb of rubber BK-1675T, treated in the same way with ordinary (commercial) polystyrene powder, is tested.

The test results are shown in Table. four.

The proposed rubber crumb treatment method makes it possible to manufacture practically all types of rubber Bites in the form of particles that do not stick together under rather harsh storage conditions. The physicomechanical indicators of vulcanizates made on the basis of rubber crumb obtained by the proposed method are superior to those of vulcanizates based on rubber produced according to patent J 2895939, and practically do not differ from the physicomechanical indicators of vulcanizates based on traditional rubber obtained without dusting.

Table 1

2.4 38.6 30.2 25.7

ZD and 3 a bout rmu p a Method for treating synthetic rubber crumbs () by mixing it with powdered vinaparomaticheskaya smogy, about and with the fact that, in order to reduce the stapleness of the crumbs during storage and improve the strength properties of the vulcanizate obtained from the crumb, the treatment is carried out with a vinyl aromatic resin, structured 5380 en and 5 10 1 baths during polymerization with monomers with two or three vinyl groups, in an amount of 2 ~ 80 parts by weight. per 100 weight. h. crumbs. Sources of information taken into account in the examination: 1. Production of tires, RTI and ATI, M, TsNIITEneftekhim, 1970, No. 8, p. 2, 2. US Patent No. 2895939, cl. 260-45 .5, 1959 - a prototype.