CS210706B1 - A method of making liquid telechelic rubber compositions for rubber articles - Google Patents

Abstract

Processing of liquid telechelic rubbers for the production of rubber products, especially technical rubber, represents one of the potential possibilities of fundamental innovation in rubber production. The method of producing mixtures of liquid telechelic rubbers for rubber products processed by procedures common in rubber practice consists in preparing the mixture from two separate, different basic batches of mixtures according to their reactivity, where the first and/or second batch contain fillers premixed with parts of the liquid rubber components and a silage activator, it is exposed to shear forces in the gap and/or to vacuum, a chain extender and a crosslinking agent are mixed into the second basic batch of the mixture, after which both basic batches of the mixture are transferred under pressure into the closed space of the mixer, where they are homogenized into a reactive mixture. The resulting mixture has a limited processability for time and temperature and is therefore used as soon as possible for vulcanization of products in molds.

Description

SUMMARY OF THE INVENTION The present invention provides a process for the manufacture of a mixture of liquid telechelic rubbers for rubber products processed by processes conventional in rubber industry.

. Processing of liquid telechelic rubbers into rubber products represents one of the potential possibilities of a fundamental innovation of rubber production. The issue of the development of raw materials, processing equipment and technologies for the preparation of mixtures and vulcanisates is addressed in all industrialized countries.

The level of quality and assortment of raw materials necessary for the preparation of rubbers, which by their properties correspond to the rubbers of solid polymers, currently requires dosing of reinforcing fillers, especially carbon black. This has a decisive impact on the choice of raw material processing technology and the design of machinery.

The previously used methods of processing mixtures filled with mineral fillers using the mixing and dispersing capabilities of multi-roll machines have not proved to be particularly satisfactory because they do not allow the use of elements of mechanization and automation of the processing process and require a significant amount of human labor.

Recently, attempts have been made in the world literature to provide a more complete solution for the treatment of liquid telechelic rubbers.

The first described process consists of premixing the liquid rubber with the mineral fillers on a double device, dispersing the mineral fillers in the liquid rubber, mixing the mixture, mixing the mixture with the vulcanizing additives and injecting the final mixture into the molds.

In the process described further, the process of processing liquid rubbers is as follows: raw material containers, 1. mixing, 1. evacuation, 2. mixing where vulcanizing agents are added, 2. evacuation and processing by casting, injection, extrusion, etc.

Similarly, the further process described for the processing of filled rubber mixtures is carried out in the following sequence: raw material, premixing, dispersion, evacuation, mixing with the addition of vulcanizing agents, molding, vulcanization and product.

The proposed technological procedures are more or less theoretical except for the first described procedure, which was tested on a model device. Mixing has not been structurally solved especially for mixtures with higher viscosity. A further drawback of this process is the placement of the reservoir after the dispersion, since the liquid rubber compositions containing the dispersed carbon black particles, when not subjected to shear stress, create significant thixotropic structures which make it difficult to transport the mixture further. This process also does not include treatment of the crosslinking agents ₍ i.e., mixing and dehumidifying and volatile components). the process also does not include dosing the mixture streams.

According to a further described process, a combination of several technological operations, in particular the dispersion of carbon black and the homogenization of several components, is envisaged in the first mixing. A disadvantage of this process is the necessity to cool the stirred mixture to a temperature of less than +20 ° C depending on the viscosity of the liquid rubber used to obtain a good dispersion of the carbon black particles. Similarly to the first described process, this treatment of the crosslinking agents and the mechanized dosing of the individual streams of the mixture are not included.

The next described technological process is similar to the first process with all the shortcomings. The only improvement is the inclusion of evacuation after the dispersion of fillers.

It has now been found how to advantageously carry out a process for the manufacture of liquid telechelic rubber compositions for rubber products processed by the conventional rubber process according to the method of the invention, wherein the composition is prepared from two separate reactivity different bases, wherein the first and / or second base batches comprise fillers premixed with portions of the liquid rubber components and a crosslinking activator, subjected to shear forces in the slit and / or vacuum, mixing the chain extender and baking agent into the second base batch of the mixture; the batches are transferred under pressure to the enclosure of the agitator where they homogenize to a reactive mixture. .

The process for preparing the compositions of the invention consists of preparing two separate batches of mixtures of different reactivity and additives, which are first processed separately and finally both are homogenized to a final reactive mixture in a selected mixing ratio. Both batches of mixtures have a shelf life of not less than three days.

The first basic charge of the mixture is mixed on the basis of liquid telechelic rubber with a filler, typically 40.0 wt. parts and activator in an amount of 4.0 wt. parts per 100.0 wt. parts of rubber in the evacuated mixing space.

The second basic batch of the blend is mixed on the basis of liquid telechelic rubber with a chain extender and a crosslinking agent in an amount of 16.0% by weight. parts per 100.0 wt. rubber parts.

The resulting reactive mixture resulting from mixing the two basic batches of the mixtures has a workability time and temperature limited _; and is therefore used immediately for vulcanizing molded articles.

The following examples show the recipes of both the basic batches of mixtures and the physico-mechanical properties of the stick products obtained.

He did

1. the basic dose of the mixture

Liquid butadiene acrylonitrile copolymer terminated with carboxyl groups of 100.0 wt. d. Sulfur activator 4.0 wt. fi. filler, high carbon black 40.0 wt. d.

2. the basic dose of the mixture

Liquid butadiene acrylonitrile copolymer terminated with carboxyl groups Chain extender and crosslinking agent Physical-mechanical properties of the product Tensile strength, MPa elongation,% elongation% modulus 100%, MPa modulus 200%, MPa modulus 300%, 1 "Pq hardness Shore A elasticity% density , kg / i and

100.0 wt. d. d.

17.7

390

3.23

7.88

13.3

1.0

Example 2

1. basic charge of a mixture of liquid butadiene rubber terminated with hydroxyl groups of 81.1 wt. d diisocyanate 31.3 wt. d filler, high-reactive carbon black 40.0 wt. d

2. a basic batch of liquid butadiene rubber terminated with hydroxyl chain extender crosslinking agent

Physical-mebhanic properties of the product Tensile strength, MPa elongation,% modulus 50%, MPa modulus 100%, MPa elongation,% Shore A elasticity,% density, kg / nP groups 66.0 wt., D

4.0 wt. d 1.0 wt. d

19.7

140.11, 9 17.4 5 89 40

1 20

Claims (1)

THE SESSION OF THE INVENTION A process for the manufacture of a mixture of liquid telechelic rubbers for rubber products processed by conventional rubber techniques, characterized in that the mixture is prepared from two separate reactivity different batches of the mixture, wherein the first and / or second base batches contain fillers premixed with portions of the liquid components. rubber and sieve activator, exposed to shear forces in the slot and / or vacuum, mix the chain extender and sieving agent into the second basic batch mixture, and then transfer the two basic batches under pressure to a closed agitator space to homogenize the reactive mixture .