RU2094442C1 - Method of preparing rubber mix - Google Patents

Abstract

FIELD: rubber industry, more particularly preparation of porous vulcanizates. SUBSTANCE: hydrolysis polyurethane is first mixed with organic "ЧХЗ-21" or "ЧХЗ-57" at 40-140 C for 0.25-1.5 h. 1.0:0.26-1.6 by weight are then mixed with other ingredients. Rubber, antiagers, vulcanizing sulfur-free group. Industrial carbon, plasticizer and sulfur are added, and vulcanization is carried out in molten salts at 230 C for 15 minutes. Hydrolysis polyurethane includes polyurethane hydrolysis waste products. Chloroprene rubber based vulcanizates have rigidity of 0.1-10.13 MPa, density of 300-380 kg/cu. m residual compressive strain of 27-35 % ozone resistance of 53-64 h. EFFECT: more efficient preparation method. 4 tbl

Description

 The invention relates to the rubber industry, in particular to methods for preparing a rubber mixture based on carbochain rubber to obtain porous vulcanizates.

 Closest to the invention is a method of preparing a rubber mixture, comprising mixing carbochain rubber with a vulcanizing group, plasticizer, antioxidant, carbon black, organic blowing agent.

The mixture is intended for the manufacture of sponge car seals and has the following composition, wt. hours per 100 wt. including rubber:
Chloroprene rubber (Denka 40) 50.00
Styrene-butadiene rubber SKMS-30-ARKM-27 50.00
Sulfur 2.00
Hexachloroparaxylene 1.00
Diphenylguanidine 1.00
Burnt Magnesia 4.00
Zinc Oxide 5.00
Carbon black P-514 40.00
Carbon black T-900 60.00
Oil PN-6 20.00
Dibutyl phthalate 10.00
Diafen FP 2.00
Acetononil 1.00
Hempor 1.50
Porofor ChHZ-21 1.50
Emulfine "K" 5.00
Calcium Naft 10.00
The known method provides for the manufacture of rubber compounds by introducing the ingredients into the mixture in a certain sequence: the mixing of rubber with pore-forming and emulphine "K" begins immediately after they are jointly loaded into a rubber mixer without any preliminary treatment of pore-forming. With this mode of preparation of the mixture, the vulcanizates are not provided with sufficient rigidity and ozone resistance.

 The technical result of the invention is a decrease in stiffness and an increase in ozone resistance of vulcanizates.

This is achieved by the fact that the rubber is first mixed with a modifying additive by the products of hydrolysis of waste products of a polyurethane fiber based on polytetramethylene ether glycol with a molecular weight of 2000, 4,4-diphenylmethanediisocyanate and 1,2-diaminopropane in a 1: 2: 1 molar ratio containing 1.5 2 , 0 wt. hydroxyl and 0.08 to 0.5 wt. amine groups pre-mixed with organic blowing agents at 40 - 140 ^o C for 0.25 1.5 hours with a mass ratio of 1.0: 0.26 1.6, respectively, after which the remaining ingredients are introduced into the mixture.

 Wastes of polyurethane fiber based on polytetramethylene ether glycol of molecular weight 2000, 4,4-diphenylmethanediisocyanate and 1,2-diaminopropane in a molar ratio of 1: 2: 1, containing 1.5 2.0 hydroxyl and 0.08 0.5 are used as hydrolysis products. wt. amine groups.

 As pore-forming agents we used: azodicarbonamide (trade name Porophore ChKhZ-21) and N, N'-dinitrosopentamethylenetetramine (trade name Hempor, ChKhZ-18), azodibutyronitrile (trade name Porophore ChKhZ-57).

The resulting paste hydrolyzed polyurethane (GP) with pore-forming has a softening temperature of 40 45 ^o C; the gas number, depending on the content of pore-forming agents, is 0.070 0.140 m ³ / kg.

Under the conditions of mixing, a finely dispersed phase of pore formers is formed in the dispersive medium of the GP. This contributes to a more uniform distribution of pore formers in the rubber matrix. When introducing into the rubber mixture GP and pore formers separately and without observing the conditions of their preliminary mixing in a mass ratio of 1 0.26 1.60 at 40 140 ^o C for 0.25 16 h, a uniform distribution of pore formers in the rubber is not achieved, which leads to obtaining large and small pores, ultimately adversely affecting the physicomechanical properties of vulcanizates, their rigidity increases. On the other hand, the use of GP in rubber compounds contributes to obtaining a microstructure that does not lead to the appearance of local stress concentrators, which is especially important in conditions of ozone aging.

The mixture of GP with blowing agents is carried out at 40 140 ^o C for 0.25 1.5 hours with a mass ratio of 1 0.26 1.60, respectively. The adoption of the lower temperature limit is explained by the fact that the production of paste is possible when the HP passes into a viscous-fluid state, i.e. 40 ^o C. At temperatures above 140 ^o C there is a decomposition of pore formers. The time interval of 0.25 to 1.5 hours is sufficient to obtain a paste that provides the necessary properties of vulcanizates.

 The content of pore formers in the paste is less than 0.26 and more than 1.60 wt. including it is not advisable, since in the first case there is an increase in the residual compressive strain of the vulcanizates, in the second, an increase in their rigidity.

 The preparation of the paste can be carried out in a heated adhesive mixer with shaped blades.

The finished product with a softening temperature of 40 45 ^o C and a gas number of 0.070 0.140 m ³ / kg is discharged from the mixer for use in rubber mixtures.

 The method is illustrated by the following examples of specific performance.

Example 1. In a heated glue mixer SRK-3 is heated by GP to 140 ^o C. Then, based on 1.0 wt. including GP in the mixer load of 0.80 hemorrh and 0.80 wt. including porphore ChHZ-21. The mixture is carried out at 140 ^o C for 15 minutes The finished product with a softening temperature of 40 ^o C and a gas number of 0.140 m ³ / kg is cooled to room temperature and sent to the site of preparation of rubber compounds. The mixture is prepared in a laboratory rubber mixer (chamber capacity 2 dm ³ ). Pasta and rubber are loaded simultaneously. The remaining ingredients are introduced into the mixture in accordance with the technological mode of manufacturing the mixture 26-517. The composition of the test mixture is shown in table. 1 (composition 3). Similarly, using the same mixing equipment and technological regime, rubber mixtures of the known method are prepared. The rubber compounds are vulcanized in a molten salt at 230 ^° C. for 15 minutes.

Example 2. Analogously to example 1. The preparation of paste GP is carried out analogously to example 1. The content of GP, hemorrhoid, porophore, is 1.00; 0.65; 0.65 wt. hours respectively. The temperature of the paste in the mixing process is 60 ^o C. The cooking time of the paste is 1 hour. Product properties: softening point 43 ^o C, gas number 0,100 m ³ / kg The composition of the mixture is given in table. 1 (composition 6).

Example 3. Analogously to example 1. The content of GP, hemorrh and porophore is 1.0; 0.13; 0.13 wt. hours respectively. The temperature of the paste during mixing is 40 ^o C. Cooking time is 1.5 hours. Product properties: softening temperature is 40 ^o C, gas number is 0.070 m ³ / kg. The composition of the mixture is given in table. 1 (composition 4).

 Physico-mechanical properties of vulcanizates according to the known method, control and according to the invention (compositions 3 to 8) are presented in table. 2. From the above data it follows that preliminary mixing of HP with pore formers with a mass ratio of 1.0 0.26 1.60 (compositions 4-6) helps to reduce stiffness from 0.15 to 0.1 0.12 MPa and increase resistance to ozone from 42 48 hours to 53 64 hours. Moreover, for vulcanizates from mixtures of the method according to the invention is also characterized by a decrease in residual compressive strain and density. Compositions 3 and 8 (with smaller and larger quantities compared with the claimed) do not satisfy the required set of physical and mechanical parameters of vulcanizates. In the first case, with an increase in the proportion of HP in the total volume of the rubber mixture, there is an increase in the residual compressive strain of the vulcanizate, and in the second an increase in its rigidity.

It should be noted that due to the inherent paste, made according to examples 1 to 3, of thixotropic properties, it is capable of hardening at 18 - 20 ^o C after 4 8 hours after its preparation. In this case, technological difficulties arise when hanging. Adding 3 to 5% wt. plasticizer in the manufacture of paste (stabiloil 18, dibutyl phthalate, etc.), you can increase the time of the paste-like state up to 20 24 hours, without affecting the physical and mechanical properties of the vulcanizates.

 The use of GP paste with blowing agents makes it possible in this recipe to partially or completely replace chloroprene rubber with a less scarce and expensive ethylene propylene.

 The compositions of the rubber compounds in the table. 3 differ from the previous ones (Table 1) in that instead of two rubbers of chloroprene and styrene-butadiene, they use a combination of trichloroprene, styrene-butadiene and ethylene-propylene. In addition, the porphore CHKhZ-21 is being replaced by the porophore CHKhZ-57.

 As follows from the table. 4 physical and mechanical parameters, a decrease in stiffness, permanent compression deformation and an increase in the ozone resistance of vulcanizates is possible only when using blowing agents in the form of a paste (compositions 5 and 6).

Claims (1)

A method of preparing a rubber mixture comprising mixing carbochain rubber with a vulcanizing group, a plasticizer, an antioxidant, carbon black, an organic blowing agent, characterized in that the rubber is first mixed with a modifying additive by the hydrolysis products of waste polyurethane fibers based on polytetramethylene ether glycol of molecular weight equal to 2000, 4, -diphenylmethanediisocyanate and 1,2-diaminopropane in a molar ratio of 1: 2: 1, containing 1.5 to 2.0 wt. hydroxyl and 0.08 to 0.5 wt. amine groups, pre-mixed with organic blowing agents at 40 140 ^o C for 0.25 1.5 hours at a mass ratio of 1.0: 0.26 1.6, respectively, after which the remaining ingredients are introduced into the mixture.

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