CS232200B1 - Method to increase the coherence of rubber products with multilayer stiffening - Google Patents

Abstract

The invention addresses increased cohesion layers of rubber products, especially hoses, with multi-layer reinforcement. So far known ways increasing the consistency between reinforcement a rubber uses either reinforcement adjustments - - impregnation - or treatment of the rubber compound. However, the modification of the rubber compound cannot be achieved between layers reinforcement. Adhesives are needed here most often the deposition of rubber cements in a volatile solvent or rubber interlayer. However, they will not ensure these operations the cohesion of the outer layers of the reinforcement with the rubber, which must provide additional operations (treatment of the substrate or rubber compound) used methods of total security therefore, there is not enough product cohesion efficient or economically demanding. Problems are solved by the way they do of the invention, wherein a coating is applied between the reinforcement layers a reactive adhesive composition which it penetrated to the rubber layers and reacted ensure overall product consistency. The adhesive is prepared from telechelic reactive functional polymer groups and diisocyanate or diepoxide, the liquid prepolymer obtained is as needed mixed with an extension, a sieve, a catalyst, a drying agent. Mix it up applied between the reinforcing layers of the product, which is vulcanized.

Description

The invention relates to a method for increasing the cohesion of layers of rubber articles, in particular hoses, with multilayer reinforcement.

Coherence requirements of high- and low-pressure hoses layers have a decisive impact on manufacturing technology. Especially low is the cohesiveness of the inner rubber and the envelope with untreated natural and synthetic reinforcements.

Pre-impregnated yarns, the deposition of rubber cement in a volatile solvent or an admixture into rubber mixtures are most commonly used to improve consistency on an industrial scale, most often based on resorcinformaldehyde resins, and the latest techniques include the addition of liquid oligomeric compositions such as hydroxyl-terminated oligobutadiene with diisocyanate mixtures. .

With the exception of rubber cements, it is possible by these methods to ensure sufficient bonding of the rubber with both the textile and the wire, but not the bonding between two fully overlapping textile or wire wraps or braids. In this - very common case - it is necessary to use either a double layer of cement or a rubber interlayer.

The use of a double cement coating in a volatile solvent has some disadvantages. Drying of cements must be envisaged, a time-consuming diffusion operation. Capture and regeneration of solvents are investment and energy intensive. Plus working

232 200 solvent environments do not meet current intelligence requirements.

If a rubber interlayer is used, the cell rubber compound for the interlayer must be adapted. - an adhesion promoter - or reinforcement material - by impregnation. The strip of the compound to be used as an interlayer must be separated in the winding to avoid sticking. This separation, often performed by sliding, then deteriorates the cohesion of the final product.

From the technological point of view, the production of rubber band means an additional operation.

Thus, the known methods of increasing the cohesion of rubber products with multilayer reinforcement are not sufficiently effective - 3GC-10CG N / m is achieved - and / or economically demanding.

These disadvantages are overcome by the method of increasing the cohesiveness of the layers of rubber articles with multilayer reinforcement according to the invention. SUMMARY OF THE INVENTION The present invention provides a liquid prepolymer of a telechelic polymer having reactive functional groups, for example, hydroxyl, amine, mercaptan, or carboxylic acid, and a diisocyanate or diepoxide, optionally mixed with an extender, catalyst, desiccant or any combination thereof. The reactive adhesive composition obtained is applied between the reinforcing layers of the article which is then vulcanized.

If an extender ^is used, it is a diol, in particular 1,4-butanediol or ethanediol. The crosslinker is, for example, triethanolamine or glycerin.

If a catalyst is to be used, as in most cases, other catalysts need to be used for the prepolymers formed by the reaction of hydroxyls, amines or mercaptans with diisocyanates - here dibutyltin laurate or triethylenediamine is used for catalysis - and other catalysates when reacting a mixture of carboxylic compounds with epoxides - then the catalyst is quinoline or a complex of chromium with fatty acids.

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When processing the viscose fiber, it is necessary to take into account a considerable moisture content of the material which reaches 5 ^ 7% by weight. ♦ Water reacts at the vulcanization temperature with isocyanate groups, thereby partially destroying and releasing carbon dioxide which can act as separator between impermeable rubber layers. . This problem is solved by adding a desiccant - calcium oxide in the form of an oil paste to the reactive prepolymer blends, water and carbon dioxide.

The deposition of the reactive adhesive composition of the present invention is defined by certain factors, both in chemical and physical terms.

At the time of application, the adhesive composition is capable of further reaction, namely:

- with added extenders and crosslinkers - formation of solid binding mass

- with reactive groups of reinforcement material - cotton, viscose, polyamide

- with rubber compound - metallization.

From a physical point of view, the viscosity of the reactive adhesive composition is an important factor. The viscosity must be so low that the adhesive can pass between the fibers (strands) of the reinforcement up to the rubber layers. The adhesive is applied between the layers of reinforcement so that a deposit is formed on one reinforcement layer and this layer is covered with the other reinforcement layer. Therefore, it is advantageous to adjust the reaction rate and the associated viscosity increase of the adhesive such that the second reinforcing layer does not slip and is well fixed when applied to the adhesive coating.

Telechelic polymers with reactive groups, with an average molecular weight of 800-8000 and a mean number functionality of 1.3-2.3, based on butadiene and its copolymers and acrylonitrile, styrene, polyisoprene and its copolymers, polyethers, and polymers are used for the preparation of adhesive compositions. polyesters.

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232 200

Examples of raw materials used to prepare the adhesive composition and their dosage are shown in Table I.

Table I

Mixture δ. Reactive M_ polymer RP parts per 100 wt.RP Diizo- cyanate extender 1. Polybutadiene 2100 terminated hydroxyly 2.1 15-35 (MDI) 0 2. r ^M -2400 1.3 5-15 (TDI) 0 3. 3300 2.3 12-25 (TDI) 0 4 · - 2100 2.1 15-35 (MDI) 0,2-6 (Buol) 5. - 2100 2.1 15-35 (MDI) 0,1-4 (glycol) 6 · - 2100 2.1 17-30 (TDI) 0,2-8 (Buol) 7. - 2100 2.1 17-30 (TDI) 5-80 (PPG) 8. copolymer 2400 styrene / butadiene termin. hydroxyl 1.7 10-25 (TDI) 0 9. copolymer 3000 but adiene / acrylonitrile term, hydroxyls 2.1 12-30 (MDI) 0,1-4 (glycol) 10. polybutadiene 3500 terminated with mercaptan groups 1.9 8-20 0,1—8 (Buol) 11. copolymer 3300 butadiene / acrylonitrile termin. amino groups 1,8 8-20 (TDI) 0 12. Polycaprolactone - 8000 tons 2 Table 2-10 (TDI) ⁰ 13. Polypropylene-2000 oxide term, hydroxyls 2 8-35 0 14. Polybutadiene 3000 terminated with carboxyl groups 2.2 15-40 (Diepoxid) 0

P232 200 wherein MDI-4,4 diphenylmethyadiisocyanate

TDI - a mixture of 2,4 and 2,6 toluene diisocyanate Buol-1,4 butanediol

Glycol-ethyndiol

Jiepoxide - 4,4 * diphenylisopropyldiglycidyl ether PPG - polypropylene oxide diol

The preparation of the composition is carried out in a reactor into which the necessary components are metered. With stirring, a prepolymer is formed which is either applied on its own to the first reinforcement layer or is mixed with an extension or a screen just prior to application. and a catalyst such as triethylenediamine, dibutyltin laurate.

Since hydroxyl-terminated liquid polybutadienes are more economically demanding than liquid polyethers, for example, mixtures of the two may be used to prepare the prepolymer. Generally, the increased content of polybutadienes or copolymers thereof increases the cohesion with the rubber due to the double bonds present and thus the possibility of metallising.

The prepared prepolymer can be stored without the access of air and moisture theoretically indefinitely, practically (in the reactor) for several months. The prepared reactive composition lasts according to the type of 5-15 min., Therefore it is prepared in an amount proportionally smaller, but also in an enclosed space, so that the operator does not come into contact with liquid toluene diisocyanate or its vapors.

Particular embodiments of the process of the invention are described in the following examples.

Example 1 (composition of the mixture according to No. 13 in Table I)

10 parts by weight of polypropylene oxide diol according to No. 13 with 32 parts by weight of diphenylmethane diisocyanate at 90 DEG C. and 8 parts of calcium oxide are added to the prepolymer. Just before application on the first textile wrap - viscose silk

232 200 are admixed with 3 parts of ethylene glycol with .2.6% triethylenediamine. The reacting hot deposit (70 ° C) solidifies and a second wrap is immediately placed in it. A rubber wrapper is formed in the crosshead of the extruder. This is followed by vulcanization at 150 ° C in hot water. The mixture of core and shell was based on butadiene styrene rubber.

Example 2 (composition of mixtures according to Nos. 4 and 13 in Table I) *

pbw according polypropylenoxiddiolu. 13A 20 parts by weight of liquid polybutadiene according to no. 4, 32 parts by weight of diphenylmethane diisocyanate and 8 parts by weight of calcium oxide formed at ^90? C for the prepolymer, before the application is added 4.5 pbw .dílu butarúiolu 2 h °. triethylenediamine. Embodiments similar to Example 1.

Example 3 (composition of the mixture according to No. 4 in Table I)

100 parts by weight of polybutadiene according to FIG. parts of a diphenylmethane diisocyanate prepolymer which is; wrapped on textile wrap. as in Example 1.

In Examples 1-3, a rubber composition based on nutadiene-styrene rubber was used for both the core and the shell.

Example 4 (composition of mixture according to No. 14 in table Ϊ)

100 parts by weight of liquid polybutanedienacrylonitrile rubber according to No. 14 with 16 parts by weight of epoxy 4,4-diphenylisopropyldiglycidyl ether - and 4 parts by weight of quinoline are mixed just prior to application to the first layer of binder-viscose rayon. A second wrap is made into this deposit and the rubber wrap is laid.

In this case, a mixture of the soul and the cover based on butadiene acrylonitrile rubber was used. After steam curing and mating, the cohesion between the textile layers and between the textile and the rubber was measured. '

Table II shows the cohesion of the individual layers as averages of the three measurements.

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Table II

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Fř. Cohesion soul-textile N / m Cohesion textile packaging N / m Cohesion textile-textile N / m 1 750 820 3 450 2 1 600 1 850 3 200 3 2 100 2 080 \ 2 700 4 1 800 1 800 2 ^ 300

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Claims (5)

Method for increasing the cohesion of rubber products, in particular hoses, with multilayer reinforcement, in particular bilayer textile or wire reinforcement, by means of a reactive adhesive composition, characterized in that of a telechelic polymer with reactive functional groups, for example hydroxyl, amine, mercaptan or carboxyl, of a diisocyanate or diepoxide, a liquid prepolymer is prepared, optionally mixed with an extender, a crosslinker, a catalyst, a drying agent or any combination thereof, wherein the reactive functional groups, including reactive groups contained in textile fibers and in impurities, especially water, are in stoichiometric ratio , the obtained reactive composition is applied between the reinforcing layers of the article, which is then vulcanized. Method according to claim 1, characterized in that the extender is a diol, in particular 1,4-butanediol or ethanediol. 3. The method of claim 1 wherein the crosslinker is triethanolamine or glycerin. 4. The process of claim 1 wherein the catalyst is dibutyltin laurate or triethylenediamine for hydroxyl, amine, mercaptan-diisocyanate-terminated telechelic polymer compositions, or quinoline or chromium fatty acid complex for telechelic-terminated telechelide polymer compositions. 5. The method according to claim 1, wherein the drying agent used in the case of non-dried textile reinforcement is, for example, calcium oxide.