DE1953624A1 - Bonding agent for the vulcanization of rubber mixtures on carrier materials and processes for their production - Google Patents

Description

GERMAN GOLD AND SILVER SCHEIDEANSTALT FORMERLY ROESSLER Frankfurt / Main, tfeissfrauenstr. 9

Bonding agent for the vulcanization of rubber compounds on carrier materials and processes for their production.

The invention relates to a novel bonding agent on the basis of formaldehyde donating "compounds for the vulcanization of rubber compounds, soft to resin Formaldehyde-capable phenols and / or amines on carrier materials such as textiles and / or contain Metals.

Objects made of rubber that are subject to considerable dynamic loads such as vehicle tires, conveyor belts or drive belts, are generally reinforced with textiles in the form of cord or cross weave. There it comes on that the rubber layer adheres as firmly as possible to the reinforcing textile material, regardless of whether it is the latter to natural fabric or to synthetic fibers made of polyesters or made of polyamides.

It is known that the textile fabric is prepared for this purpose using rubber latex and a phenol-formaldehyde condensation product, Resorcinol is usually used as the phenol. On the one hand, this resin component reacts with the functional groups of the respective textile material, on the other hand with the elastomer used and so causes the adhesion of the applied rubber layer to the fabric.

If the elastomer, be it natural or synthetic rubber, is reinforced with carbon black as a filler, as usual, and resorcinol and hexamethylenetetramine, the latter as formaldehyde generators, are added to this mixture, then resin formation occurs

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during vulcanization and causes the vulcanizate to adhere to the prepared or unprepared textiles. However, the increased demands placed on such a composite body in practice require the highest possible adhesion of the elastomer on the fabric, so that the filled rubber layer and the textile fabric even under greater dynamic stress do not separate from each other.

According to a known method, an improvement in the adhesion of mixtures of natural or synthetic rubber on prepared and unprepared textiles by means of condensation products of phenols or amines and aldehydes capable of resin formation can be achieved by using a rubber mixture in which as a filler active silicic acid in amounts of from Io to 1oo parts by weight, calculated on 1oo wt. parts of rubber, is incorporated alone or in a blend with carbon black, wherein as active silica, both precipitated from water glass by means of acids in finely distributed, amorphous form, as well as the Silicas produced thermally directly as finely divided powder with a specific BET surface area of 3o - 400 m / g and an average primary particle size of 1o - hoo microns can be used. The reaction of the resin components with the functional groups of the textile material, the rubber and the reinforcing filler enables a significant increase in the adhesion values.

Condensation products of resorcinol and formaldehyde have proven to be optimally effective. By grinding of equal parts of resorcinol and finely divided silicas or adsorptive coating a solution of the resin formers on the silica, the disadvantage of the difficult Dispergierbarkelt of resorcinol are fixed · As Fo rmal de-

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The hyd component or formaldehyde donor is used for finely ground products Hexamethylenetetramine, which during the vulcanization »temperature those required for resin formation with the resorcinol Formaldehyde developed.

Even if with this system, especially with natural rubber and Also various synthetic rubber aortas, very good effectiveness was achieved, so it has in the course of the Further development work has shown that hexamethylenetetramine does not achieve optimal adhesion values for every formulation can be. In addition, there is a certain amount of fiber damage Effect on polyester fibers as a result of the amines or TMs formed during the decomposition of hexamethylenetetramine

Ammonia.

The invention was based on the task as a bonding agent for the vulcanization of rubber compounds containing fillers, in particular silica, which contain phenols and / or amines capable of resin formation with formaldehyde, a formaldehyde donor on carrier materials indicate that does not have the disadvantages observed with hexamethylenetetramine and, moreover, as well Hexamethylenetetramine only with the applied vulcanization temperature of rubber compounds formaldehyde for the Gives off condensation process with resorcinol. I.

It has surprisingly been found that of the possible formaldehyde donors, such as, for example, the (06- » ß ~ and / - polyoxymethylenes), the ε-polyoxymethylenes as formaldehyde donors for the stated application are most effective.

The 6-polyoxymethylenes are mixtures linear polyoxyraethylene glycols of the type

HO (CH ₂ O) _n - H,

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whose average degree of condensation η (chain length of the Formaldehyde units) is not less than 100, but in the order of magnitude of over 2oo

These formaldehyde donors, referred to below as FOD, are produced in a relatively simple manner 3-day tempering of paraformaldehyde HO · (CH θ) · H (n, mean chain length> · 3ο - 1oo) at approx. 7o ° C. This Paraformaldehyde is produced by condensation of aqueous formaldehyde solution with the addition of a slightly increased acid concentration obtain. Surprisingly, it isn't

possible to obtain FOD by annealing N-paraformaldehyde. N-Paraformaldehyde is produced by the condensation of aqueous Formaldehyde solution, which usually contains only a very small amount of formic acid, is produced.

In the production of FOD, one can continue to proceed in such a way that, by treating the paraformaldehyde, the possible Any remaining low molecular weight components can be removed using highly dilute sulfuric acid or sodium hydroxide solution. The residue remaining after filtration is then washed out with water again under the same Conditions, i.e., about 3 days at about 7o C, annealed.

The usefulness of the FOD obtained in this way for the stated application can be checked by that the product practically no longer meets the conditions of the so-called "resorcinol test", as it is in U.S. U.S. Patent 2 4p1,981 and U.S. Patent 2,5 "x 9,550.

Compared to hexamethylenetetramine, as can be seen from the following examples, FOD can be used particularly with peroxidically crosslinked SBR mixtures, Hypalon, EPDM adhesive mixtures as well as chloaoprene rubber for polyester

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and polyester-nylon blended fabrics, better adhesion values can be achieved.

The mixtures given in the examples are prepared in a known manner, either by adding active silicas and resorcinol added separately to the rubber mixture and im Kneaders are mixed or premixes of resorcinol and active silicic acid are first produced and these are supplemented further active silica until the total amount is reached of filler are added to the rubber sheet on the roller. The FOD can be mixed in in the same way.

It has already been mentioned that resorcinol can be dissolved in a suitable solvent, such as toluene, can apply directly to the silica as a carrier substance, the Phenol derivative is bound adsorptively. Then, after drying with recovery of the solvent, the coated Silica in powder form of the rubber mixture on the Roll or in the kneader added.

In the same way as resorcinol, one can also use the second Resin component FOD as an aldehyde donor, for better distribution and easier mixing in the rubber with the Grind active silica or apply it to the silica by adsorption in solution. The addition to the rubber mixture then takes place after the first components have been mixed in, with the addition of corresponding additional amounts of silica and optionally with the addition of active soot as a further Filler. As is known, the tissue adhesion is still favored through intimate contact of the silanol groups on the silica surface it increases the functional groups of the rubbers.

Both those precipitated from water glass solutions by means of mineral acids in finely divided, amorphous form, as well as those produced by thermal means directly as finely divided powder with a spec. BET surface area of Jo - 400 m / g and a medium one

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- 6 primary part sizes 1o - 4o m microns can be used.

The rait FOD achieved in the following examples Adhesion results are reproduced on the basis of suitable mixing recipes.

Example 1 ι styrene-butadiene / natural rubber blend 75/25

Mixture 1 with Hexa Mixture 2 with FOD methylene tetramine

Styrene butadiene

^ Copolymer (SBR 15o2) 75

Natural rubber 25

Phenyl-iS-naphthylamine 1

Active soot 3o

Active silica 12.5

High aroma. Plasticizer 7

Zinc oxide 1o

Sulfur 2.3

Sulfenamide accelerator 1.4 1.4

Cofill 11 6 6 -

Hexamethylenetetramine 1.5 ~

FOD 26 - 1.5

Diphenylguanidine - ο, k

Vulcanization 3o min / 15o ° C

Adhesion (kp / 2.5 cm)

on polyamide not prepared 18.5 22

not prepared on polyester 12 16

· ' - 5 15th 25th 3ο 3 12, 7th 1ο 2

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Example 2 ? Chlorosulfonated polyethylene

Mixture 1 with hexa-Mixture 2 with FOD methy1entetramine

Chlorosulfonated

Polyethylene 1oo 1oo

Active soot 3o 3o

Active silica 12 12

Naphtha. Plasticizer 1o Io

Magnesia usta 1o * Io

PbO Id 1o

Anti-aging agents 2 2

Dibenzothiazyl disulfide o, 5 o, 5

Dipentymethylene thiuram

tetrasulfide ο, 75 ο, 75

Cofill 11 6 6

Hexamethylenetetramine 1.5

FOD 26 - 1.5

Vulcanization 2o min / 16o ° C

Adhesion (kp / 2.5 cm)

on polyamide not prepared 1.5 13

not prepared on polyester k 1 ^

-B-

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Example 3: Chioroprene chewing school

Mixture 1 with Hexa Mixture 2 with FOd

methylene tetrarnine 1 οό 1.5 1 oo Chi oroprene chewing school 2.5 2.5 Stearic acid 4th 4th Magnesia usta 5 5 zinc oxide 1 1 Anti-aging agents 18.5 IR, 5 Active silica 3o 3o kaolin ίο 1o Tricresyl phosphate Io 1o Napthen. Plasticizers 3 3 Cofill 11 1 1 sulfur Tetramethylthiuramdxsulfid ο, 6 o, 7 Hexamethylenetetramine - FOD 26 1.5

Vulcanization 2o min / i5o ° C adhesion (kp / 2.5 cm)

not prepared on polyamide 24

not prepared on polyester 39

9 -

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Example 4: ethylene-propylene terpolymer

Mis osition 1 me. Ilexa Mis ellation 2 with FOD methylentetramine

Ä tliy 1 en-Propy 1 en-

Terpolymer. loo 1oo

Active silica 15 15

Active carbon 25 25

Naphtha. Weicamacher 5 5

Stearic acid 3 _p 3

Zinc oxide 5 ^

Cofill 11 6 6

Tetrametlaylthiuram disulfide 1.7 1

Mercaptobenzothiazole 1 1

Sulfur 1.6 1.6

Hexamethylenetetramine 1.5 -

FOD 26 - 1.5

Vulcanization 3ο min / i6o C

Adhesion (kp / 2.5 cm)

not prepared on polyamide 15. 2o

not prepared on polyester 13 ² B

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Claims (2)

- 1ο - claims 1) Adhesive strength agent materials on the basis of formaldehyde-donating compounds for the retreading of fillers _r, in particular silica rubber compounds containing, which enabled for resin formation and formaldehyde phenols and / or amines, to support materials, characterized in that it consists of C ^ - Polyoxymethylenes of the type * HO '(CH ₂ O) _n H, their average degree of condensation η (chain length of the "formaldehyde units) in the range from 100 to 500, preferably in the range from 200 to 500, lies. 2.) Process for the production of a bonding agent according to Claim 1, characterized in that polyoxymethylenes with an average chain length of ^ 3o to 1oo im Temperature range from 6o to 8o ° C over a period of two to four days. 3.) Process according to claim 2, characterized in that polyoxymethylene is first treated with highly dilute sulfuric acid or sodium hydroxide solution and the washed residue remaining after filtration is subjected to tempering. Go / Spi
23.1ο. 69 109819/1973