DE1470776A1 - Process for improving the adhesive strength of natural and synthetic rubber or rubber mixtures on synthetic fibers - Google Patents

Description

"Method of improving the adhesive strength of naturlichom and synthetic rubber or rubber mixtures on synthetic fibers "There are already numerous proposals for achieving a stable and also under dynamic Conditions that is, for example, under tensile stresses-sufficiently firm Connection between rubber and synthetic fiber material has been made. According to In these known processes, the fibers are usually replaced by an acidic solution, an emulsion or dispersion, which contain the actual adhesive. Subsequently on it the fiber material is then dried at an elevated temperature and is then suitable to be vulcanized into rubber.

Such methods are found, for example, in the treatment of polyamide fibers Use; here the auric bath contains, in addition to the long-known raft, namely the natural rubber-latex-resorcinol-formaldehyde, another one Content of latex based on vinyl pyride interpolymers. These procedures lead generally with polyamide fibers to achieve satisfactory adhesion values on rubber.

Other synthetic fibers, especially those based on Polyesters, for example based on polyethylene glycol terephthalate, leave not treat by the known methods in such a way that their adhesive strength on rubber could be described as satisfactory. Rather, the achievement made Adequate adhesion of polyester fibers to rubber has so far posed great difficulties. The use of the well-known adhesive systems as well as the vinylpyridinterpolymer-containing ones just described Adhesive emulsion therefore only led to very low adhesion values. So one was so far for the purpose of achieving a well-adhering rubber-polyester bond thereon instructed to carry out complicated and expensive multi-step processes. According to this In the process, the polyester fiber material is first using a pretreatment subjected to an aqueous and in other cases also non-aqueous solution or emulsion with simultaneous or subsequent heat treatment of the fiber and among themselves subsequent further treatment using known aqueous Emulsions and then repeated drying.

The baths described for the pretreatment of the fiber contain, for example Isocyanates, triallyl isocyanurate and polyvinyl chloride dispersions.

It has now surprisingly been found that to achieve very good adhesion of rubber to synthetic fibers, in particular of polyester fibers, the complex and cumbersome multi-bath procedure thereby ersetsen last that, according to the present invention, the fiber material before dom Embedding in the chewing cheek in a one-step bath process with aqueous emulsions is treated by blocked isocyanates, sorsugswelse polyisocyanates.-Here is therefore only prepared and dried once.

The additions of masked isocyanates sun one-step bath bring a 2Surprising and great improvement in the adhesion values of synthetic fibers to rubber with himself.

In contrast, epoxies alone lag behind under the conditions investigated Implementation of a single bath process and after a subsequent drying period, the vorsugsvesse lasted an hour, none or at best only a weak one Adhesive effect produced.

It has also surprisingly been found that a combination of precapped isocyanates, in particular of polyisocyanates, with epoxides, preferably with polymeric epoxides, these active ingredients in the form of an aqueous emulsion were used in the single bath process, an extraordinarily favorable influence on the Adhesion of the synthetic fibers, especially the polyester fibers, causes rubber. The adhesive values obtained in this way are largely far above the level of the adhesive values, which can be achieved in the method of treatment g of polyamides described at the outset are.

According to a variant of the invention, the new method is characterized in that that a treatment bath is used, which organic solvents, preferably Contains methylene chloride, to effect a better emulsification of the bath ingredients. These organic solvents can optionally be used before the introduction of the Fasormatertal removed from the bath, for example by aborting.

According to a further preferred embodiment of the present invention the treatment bath contains emulsifiers.

The implementation of the method according to the present invention enables the manufacture of fabric-containing rubber articles such as Tires, drive belts, conveyor belts, hoses, containers, inflatable products, like lifeboats and transport islands.

That. Essence of the present invention is illustrated in the following examples, represent the preferred embodiments, further explained. In the examples were a polyethylene glycol terephthalate monofilament of 0.7 mm diameter and a Polycaprolactam monofilament also used with a diameter of 0.7 mm. The usage of thick monofilaments when testing new adhesives has the great advantage that no obscuration of the adhesive values due to mechanical anchoring of the rubber mixture on cord or fabric is possible.

The preparation of the monofilaments was carried out so that the textiles Immersed in the preparation bath for 1 minute each, then suspended vertically half an hour in the air and then 1 hour at 130 C in the drying cabinet were dried.

The adhesive strength was tested by rubbing the monofilaments from the rubber mixture in a Drage-Multi-Test at room temperature as well as at 80 ° C. In some cases dynamic adhesion tests were carried out.

The rubber mixture used in the examples was a practical carbon black-reinforced one Natural rubber compound used.

The vulcanization took place within 25 minutes at 160 ° C. The The stamp pressure of the press was such that a pressure was applied during vulcanization of 20 atmospheres on the rubber compound.

The cured samples were left for at least 24 hours before testing stored.

In the examples, emulsions were used, which are briefly described below as "Emulsion A", "Emulsion B", etc. are designated. The emulsions were made using a high-speed stirrer of the "Ultra-Turrax" type.

The numbers mean parts by weight, if not expressly something else is stated.

Emulsion A: Desmodur AP stable (Farbenfabriken Bayer) 20 (existing from a phenol-capped triisocyanate) methylene chloride 30 water 60 emulsifier 20 drops of emulsion B: Desmodur R-phenol adduct 20 (consisting of phenol-capped Triphenylmethane triisocyanate) chloroform 20 wet 60 emulsifier 20 drops of emulsion C: Oxiron 2000 (Food Mach. Chemical Comp.) 20 (Consists of epoxidized polybutadiene) Chloroform 20 Wet 60 Emulsifier 20 drops Emulsion D: araldite D (Ciba) 20 (consisting of an epoxy resin based on 4,4'-dioxyphenylpropane diglyzidyl ether) Chloroform 20 20? 60 60 emulsifier 20 drops of emulsion E: vinylcycloheylene dioxide 1 chloroform 19 .. 'water 80 emulsifier 20 drops Example 1: Polyethylene glycol terephthalate monofilament were prepared with an emulsion of the following composition: 100 g emulsion A was mixed with 2.5 g vinyl pyridine latex (Politone, 40 percent).

Example 2: Polyethylene glycol terephthalate monofilaments were with a Prepared emulsion of the following composition: The Desmodur R phenol adduct, which is used in emulsion B, by reaction of one mole of Desmodur R with 9 moles of phenol in boiling toluene and subsequent precipitation with petroleum ether obtain.

100 g of emulsion B were mixed with 0.3 g of natural rubber latex (60 percent) and 3 g vinyl pyridene latex (Politone, 40 percent) added.

Using the preparation baths given in Examples 1 and 2 usable adhesive values of medium quality are obtained, which, however, do not quite match the Alert achieved with conventional methods on rayon or polyamide.

Example 5: Polyethylene glycol terephthalate monofilaments were with a Emulsion prepared with the following composition: 100 g of emulsion B were mixed with 20 g Emulsion C mixed; this mixture was mixed with 2 g of natural rubber latex (60 percent) and 3 g vinyl pyridine latex (Politone 40 percent) added.

Example 4: Polyethylene glycol terephthalate monofilaments were with a Emulsion prepared with the following composition: 100 g of emulsion B were mixed with 29 g Emulsion D mixed; 2 g of natural rubber latex (60 percent) were added to the and 3 g vinyl pyridine latex (Politone 40 percent) added.

By using masked polyisocyanates in combination with polymeric epoxides, as described in Examples 3 and 4, are Unusually high adhesion values are achieved, as shown in the table below can be seen.

But monomeric epoxides also produce this effect, or maybe not pronounced as the following example shows.

Example 5: Polyethylene glycol terephthalate monofilaments were with a Prepared emulsion of the following composition: 100 g of emulsion B were mixed with 20 g of Emulsion E; 2 g of natural rubber latex were added to the mixture (60 percent) and 3 g vinylpyridine latex (Politone 40 percent) added * Example 6: Polycaprolactam monofilaments were with an emulsion of the following composition prepared 100 g of emulsion B were mixed with 20 g of emulsion C; this mixture 2 g natural rubber lates (60 percent) and 3 g vinyl pyridine latex (Politone 40 percent) added.

The following table shows some static adhesion values of the Examples compiled experiments described. Ala comparison is a polycaprolactam monofilament, which under optimal conditions in a conventional vinylpyridine-latex-resorcinol-formaldehyde bath was treated (called "Standard").

The second cleat shows the adhesion value, that of the conventional one Preparation of a polyester monofilament with vinylpyridine-latex-resorcinol-formaldehyde obtained (called "polyester conventional").

All listed adhesion values are mean values from at least 5 individual quantities. The spread of the measurements was generally small. The adhesion values are in Kilopond stated per test specimen.

TABLE Preparation and material Adhesion values (kp / test specimen) "Standard" (Polyamide) 11, 8 "conventional polyester" 0, 2 example 1 (polyester) 6, 4 example 2 "6.5 Example 3" 15.5 Example 4 "15.5 Example 5" 7.7 Example 6 (polyamide) 9, 0 Regarding the adhesion values obtained in Examples 3 and 4, it is also noted that that the adhesion was so good that in most Sillon the thread was 15.5 kg tore without the rubber-textile bond having loosened.

The high adhesive values were retained even at 80 ° C.

Claims (6)

Claims: 1. Procedure to improve the adhesive strength from natural and synthetic rubber or rubber mixtures to synthetic Fibers, especially polyester fibers, are noticeable t that the fiber material is in a one-step bath process before it is embedded in the rubber with aqueous emulsions of blocked isocyanates, preferably polyisocyanates, is treated. 2. The method according to claim 1, d a d u r c h g e k e n nz e i c h n e t that the treatment in the presence of epoxides, preferably polymeric epoxides, is carried out in the form of their aqueous emulsion. 3. The method according to claims 1 and 2, d a d u r c h g e k e n It is not noted that a treatment bath is used which contains organic solvents, preferably methylene chloride, to effect a better emulsification of the bath ingredients contains. 4. The method according to claim 3, d a d u r c h g e k e n nz e i c h n e t that the organic solvents are made before the introduction of the fiber material removed from the bathroom. 5. The method according to claim 4, d a d u r c h g e k e n nz e i c h n e t that the organic solvents are removed by stripping. 6. The method according to claims 1 to 5, d a d u r c h g e k e n It is noted that the treatment bath contains emulsifying agents.