RU2740555C1 - Method of vulcanisation of polymer composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method for vulcanisation of polymer compositions and can be used for making brewing chambers, diaphragms and sealing sealed joints in vulcanising equipment for tires and rubber articles: autoclaves, vulcanizer formers, vertical stack presses operated for a long time in a moist steam-air medium with high temperature and high pressure. Method includes vulcanisation of article at the beginning at steam temperature of 165–170 °C for 50–45 minutes, and then at temperature of 195–205 °C for 10–5 minutes.

EFFECT: technical result is higher strength, hardness, tear resistance of article.

1 cl, 4 tbl, 2 ex

Description

The invention relates to the processes of vulcanization of polymer compositions, in particular, rubber compounds based on butyl rubber and can be used for the manufacture of cooking chambers, diaphragms and sealing hermetic joints in vulcanization equipment for tires and rubber goods: autoclaves, shapers-vulcanizers, vertical deck presses, operated for a long time time in a humid vapor-air environment with high temperature and high pressure.

A known method of vulcanization of a polymer composition (see DL Fedyukin, FA Makhlis "Technical and technological properties of rubbers" M. "Chemistry", 1985, pp. 130-131, Koshelev FF, etc. " General rubber technology "M." Chemistry "1978, pp. 92-95), when rubber compounds based on butyl rubber (BC) are vulcanized with sulfur with accelerators, alkyl phenol-formaldehyde resins in combination with chlorine-containing polymers with the supply of a heat carrier with a constant constant temperature.

The disadvantages of the known method of vulcanization is that the operational resistance of rubbers based on butyl rubber at a constant vulcanization temperature is reduced and the result is lowered against the required heat resistance, endurance, durability.

The closest in technical essence and the achieved technical result - the prototype is a method of vulcanization of a polymer composition based on butyl rubber (see A.E. Kornev et al. "Technology of elastomeric materials" M. GOU VPO Moscow State Academy of Fine Chemical Technology named after M.V. Lomonosov, 2009, pp. 86-88) in which a workpiece is placed in a mold and a heat carrier with a constant vulcanization temperature of 150 ° C is supplied.

The disadvantages of the known prototype are also the fact that at a constant low vulcanization temperature, the operational and chemical resistance of rubbers based on butyl rubber of the product decreases to low physical and mechanical parameters, such as hardness, tensile strength, tear resistance.

The technical result of the claimed invention is the elimination of these disadvantages, increased performance by improving the physical and mechanical parameters: strength, hardness, tear resistance.

The specified technical result is achieved due to the fact that the method of vulcanization of a polymer composition, for example, a rubber mixture based on butyl rubber, which consists in inserting a workpiece into a mold and supplying a heat carrier mainly, steam, differs in that initially the product is vulcanized at a steam temperature of 165 -170 ° C for 50-45 minutes, and then at 195-205 ° C for 10-5 minutes.

These products, cooking chambers, diaphragms and sealing joints must be airtight and have a long service life.

In the process of vulcanization of tires and rubber-technical products, due to sharp changes in high temperature and pressure associated with the peculiarities of the vulcanization mode, the time spent in complex vapor-air environments, the cooking chambers mounted on the vulcanization equipment, diaphragms and sealing hermetic joints lose their operational properties: heat resistance , endurance (in terms of the service life of the sealing movable contact), durability (time of continuous stay in the unit) and prematurely fails.

Due to the low flexibility of the molecular chains of butyl rubber and the high density of their packaging, by changing the formulation of the rubber mixture based on butyl rubber by introducing ingredients of various natures aimed at increasing the heat resistance of strength, and the hardness of even reinforcing fillers in products, there is no significant increase in physical and mechanical properties, it is proposed to carry out vulcanization rubber mixture in 2 stages in the range of butyl rubber brands BK-0845 TD, BK-1030T, BK-1645T, BK-1675T, produced by synthetic rubber enterprises.

The essence of the invention is illustrated by the following examples.

Example 1

The production of a rubber mixture based on butyl rubber of the BK-0845TD brand with a minimum limit is carried out in a standard rubber mixer in two stages:

at the first stage, a masterbatch is made, and at the second stage, a vulcanizing group is introduced into it.

Then, on an extruder with a profile in the head of the required shape and size, blanks for cooking chambers, diaphragms, and sealing hermetic joints are produced from the rubber mixture.

Then, depending on the purpose, the blanks for diaphragms are vulcanized in an injection press, cooking chambers in a vulcanization press.

Workpieces are placed in a mold and a heat carrier-steam with a temperature of 165 ° C and a pressure of 0.5 MPa is fed into the steam chamber of the vulcanization equipment and cured for 50 minutes, after which steam is supplied with a temperature of 195 ° C and a pressure of 1.2 MPa and cure for another 10 minutes.

The finished product was removed from the mold and sent further to the final operations of cutting the extrusions and acceptance by the Quality Control Department.

Example 2

The production of a rubber compound based on butyl rubber of the BK-1675T brand with maximum non-limitation is carried out in a standard rubber mixer in two stages:

at the first stage, a masterbatch is made, and at the second stage, a vulcanizing group is introduced into it.

Then, on an extruder with a profile in the head of the required shape and size, blanks for cooking chambers, diaphragms, and sealing hermetic joints are produced from the rubber mixture.

Then, depending on the purpose, the blanks for diaphragms are vulcanized in an injection press, cooking chambers in a vulcanization press.

Workpieces are placed in a mold and a heat carrier-steam with a temperature of 170 ° C and a pressure of 0.6 MPa is fed into the steam chamber of the vulcanization equipment and cured for 45 minutes, after which steam is supplied with a temperature of 205 ° C and a pressure of 1.4 MPa and vulcanize for another 5 minutes.

The finished product was removed from the mold and sent further to the final operations of cutting the extrusions and acceptance by the Quality Control Department.

To verify the validity of the industrial applicability of the proposed invention, tests were carried out by comparing the physical and mechanical parameters in laboratory conditions on the basis of butyl rubber after vulcanization of samples in one stage and according to the proposed invention in two stages.

Two rubber compounds were made on the basis of BK-0845DT butyl rubber with a minimum unsaturation of 0.8% (mol) and on the basis of BK-1675T butyl rubber with a maximum unsaturation of 1.6% (mol). The formulation of rubber compounds is presented in table 1.

The manufacture of rubber mixtures was carried out on laboratory rolls Lb320-160 / 160 with a mixing mode of 30 min. at a roll temperature of 40-50 ° C.

The vulcanization of rubber samples was carried out in a vulcanization press "ZOOS" with double-sided heating of the plates in a closed mold in accordance with GOST 30263-96 according to the modes presented in table 2.

Samples 1 and 2 were vulcanized in a one-stage mode at t = 150 ° C for 65 minutes, and sample 3 with a minimum unsaturation in the mode in two stages: the first stage was carried out at t = 165 ° C, steam supplied to the mold for 50 minutes, and then the steam temperature rose to 195 ° C and the second stage of vulcanization lasted for 10 minutes. Sample 4 with maximum unsaturation at the first stage was vulcanized at t = 170 ° C for 45 minutes, and at the second stage the temperature was increased to 205 ° C and the vulcanization process took another 5 minutes.

Determination of physical and mechanical parameters of vulcanizates was carried out on a tensile testing machine ZwikRoill according to GOST 270-75. The test results are shown in Table 3.

To determine the effect of temperature on the heat resistance of vulcanizate samples, they were thermally aged at 200 ° C for 4 hours.

The results of the work are presented in table 4.

As can be seen from Table 2, the heat resistance of specimens 3 and 4 after two-stage vulcanization has rather high indicators compared to specimens with vulcanized in one-stage mode.

The use of the invention will improve the performance of vulcanized products in contact with various media by increasing the strength and hardness.

Claims (1)

A method for vulcanizing a polymer composition, for example a rubber compound based on butyl rubber, which consists in filling the mold of a workpiece with a heat carrier, mainly steam, characterized in that at the beginning, the vulcanization of the product is carried out at a steam temperature of 165-170 ° C for 50- 45 minutes, and then at 195-205 ° C for 10-5 minutes.