RU2220985C1 - Rubber compound softener preparation method - Google Patents

Abstract

FIELD: rubber industry. SUBSTANCE: method consists in preparing mix of ground rubber waste (5-90%) with still residue from rectification of ethylene oligomer production products (10-95%), which mix is then thermally treated at 150-250 C during 0.5 to 24 h. EFFECT: limited use of valuable material resources due to reuse of rubber waste. 1 tbl, 12 ex

Description

 The invention can be used in the tire and rubber industry to obtain a softener rubber compounds based on rubber waste.

 As softeners and plasticizers are used products of oil refining, coal, shale, substances of plant origin, etc. Mineral oils and extracts of the selective purification of oils, fuel oils, tar, tar, petroleum jelly, paraffins, ceresins are most widely used for these purposes. ozokerites, petrolatum, bottoms from oil refining processes.

 PN-6Sh oil is currently widely used as a softener in the tire industry.

It is known that PN-6Sh oil contains light aromatic hydrocarbons up to 18-20%, average aromatic hydrocarbons 55-65%. Oil PN-6Sh is characterized by an aniline point of 55-67 ^o С, which indicates a high content of aromatic compounds (Handbook of rubber worker: Materials of rubber production. / Ed. By P.I. Zakharchenko, F.I. Yashunskaya, V.F. Evstratova. - M .: Chemistry, 1971.- S. 443-446).

 Also, PN-6Sh oil, like all other mineral oils, contains polycyclic aromatic substances (RAS), while these aromatic oils have a certain carcinogenic potential (Savvinova Yu.A., Vasilyev N.Ya. / Toxic properties of aromatic oils - softeners.// Prostor, -1999.- 9.- P.44-47).

 All this requires the replacement of aromatic process oils used as rubber softeners with safer oils in terms of maintaining the health of tire industry workers.

 Distillate aromatic extracts with a high content of polycyclic aromatic hydrocarbons are widely used as aromatic process oils for the production of oil-filled NK and SK, as well as in finished tires. However, various studies have shown the potential carcinogenicity of these oils. The European legislation (EC Directive 67/548) (EEC) concerning substances classifies these distillate aromatic extracts as carcinogenic and gives these mineral oils the hazardous substance marking “R45” (can cause cancer) and the designation “T” (skull and bones).

 A Kemi study, published in Sweden in 1994, emphasized that environmental problems arise with these potentially carcinogenic products in tire treads. The total wear during the operation of tires in Sweden was estimated at 10,000 tons / year, of which approximately 14 tons / year were polycyclic aromatic hydrocarbons (KGK Kautschuk Gummi Kunststoffe, 48 (1995) 237).

 The PN-6Sh oil, widely used as a rubber softener, which is a by-product of the oil refining process, is gradually disappearing from the market. Currently, this is due to the tendency to increase the depth of oil refining using new modern oil refining processes. With new refining processes, there are no by-products such as PN-6 oil (Lemmon. M., et.al., Impact of base oil trends on future lubricant formulations - the additive perspective. Presentation 1997 National Petroleum Refiners Association annual meeting, San Antonio, USA 16-18 March 1997); (Juergen E. Pocklington, Deutsche Shell AG, Germany. // A safer alternative to aromatik process oils. - Tire Technologi International. -1998.- p. 43-47).

 In addition to softeners obtained as by-products and waste from various oil refining processes, softeners obtained in other ways are used in the rubber industry.

The softeners obtained by pyrolytic decomposition of used tires contain significantly less aromatic compounds. In US Pat. US 4175211 (IPC 7 C07C-003/26, published on November 20, 1979) describes a method for processing used tires, which includes grinding them to sizes of 4-0.75 mm, mixing with petroleum products, heating the resulting mixture in a reactor at 65-370 ^o C for a time sufficient to dissolve the material, the catalytic cracking of the resulting solution in the reactor at a temperature of not lower than 450 ^o C and elevated pressure, discharging product from the reactor and its subsequent distillation to form gaseous products, gasoline, light oil and heavy fractions products. The resulting heavy fractions are used as emollients.

 The disadvantage of the emollient obtained by this method should be attributed to the fact that it contains aromatic substances originally present in the original petroleum products.

A softener is also known (US Patent 5157176, IPC 7 G 10L 001/16: G10L 005/00: C07C-001/00, publ. 10/20/1992), obtained from used tires, consisting of the following stages: placing the tire or crushed rubber in a closed reactor, pyrolytic heating in countercurrent pyrolysis gas at a temperature of 176 ^o C (350 ^o F) to 260 ^o C (500 ^o F) with control of the oxygen content in this gas (pyrolysis gas is obtained by partial burning of waste tires); fractional separation of pyrolytic gases and oil after the reactor. After separation, the resulting oil is used as a softener.

The softener has a flash point starting from 171 ^o C (340 ^o F), which is lower than the oil PN-6Sh, and therefore is more fire hazard.

 The objective of the invention is to reduce the proportion of aromatic compounds in the softener, increasing the flash point and expanding the raw material base of softeners of rubber compounds.

The problem is solved in that the claimed emollient is obtained as follows: creating a mixture of crushed rubber waste with a bottom residue of rectification of the products of production of ethylene oligomers, the emollient is obtained by heat treatment of the mixture at a temperature of 150-250 ^o C for 0.5-24 hours in the following ratio components, wt.%:
Ground rubber waste - 5-90
VAT residue rectification products of the production of ethylene oligomers - 10-95
The bottom residue of the rectification of the products of the production of ethylene oligomers is a mixture of olefinic hydrocarbons with different lengths of the hydrocarbon chain. Hydrocarbons are mainly of a linear structure with С _n Н _2n composition, where n for a significant amount of hydrocarbons is 28 <n <60.

 It does not contain aromatic compounds, and its introduction into the composition of the mixture helps to reduce the content of aromatic compounds in the softener compared to their content in the original rubber waste.

 For the process, crushed rubber wastes were used, for example, rubber crumb obtained from the recycling of used tires, rough rubber, etc.

 The technical solution is illustrated by the following examples of specific performance.

 Example 1

The softener is prepared as follows: 47 g of crushed rubber wastes are placed in the reactor, 20 g of bottoms from the rectification of the products of ethylene oligomers production are heated and heated at a temperature of 150 ^{° C.} with constant stirring for 180 minutes. The resulting mass is discharged from the reactor, cooled to ambient temperature and averaged on laboratory rollers or on mixing equipment.

 The flash point in an open crucible is determined according to GOST 26378-84. See table.

 Aniline point is determined according to GOST 12329-77. See table.

 Example 2-12

 The softener is prepared in the same manner as in example 1, the ratio of components and mode are shown in the table.

 As can be seen from the table, the proposed emollient is characterized by a higher aniline point in comparison with the PN-6Sh oil and a higher flash point compared with the emollient described in US patent 5157176.

 A higher aniline point of the emollient obtained by us indicates a lower content of aromatic compounds in comparison with the widely used PN-6Sh oil.

 The higher flash point of the emollient obtained by us helps to reduce the fire hazard when used for the manufacture of rubber compounds.

 The softener offered by us expands the market of softeners.

 The use of rubber waste in the production of softener helps to save material resources and solves the problem of recovery of rubber waste.

Claims (1)

A method of obtaining a softener of a rubber mixture containing crushed rubber waste, followed by heat treatment, characterized in that an additional bottoms distillation residue is introduced from the production of ethylene oligomers, the softener is obtained by heat treatment of the mixture at a temperature of 150-250 ° C for 0.5-24 hours in the following ratio of components, wt.%: Ground rubber waste 5-90 VAT residue rectification products of the production of ethylene oligomers 10-95

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