DE1263290B - Process for firmly bonding metals or metal alloys to natural or synthetic rubber - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl: C08c

C08d

German class: 39b - & 2 &rf'fed

Number: 1 263 290

File number: F 44556IV d / 39 b

Filing date: November 27, 1964

Opening day: March 14, 1968

A number of binders are already available for bonding rubber compounds to metals by vulcanization has been proposed. Among other things, it is known synthetic polymers made from butadiene and Methacrylic acid alone and together with chlorinated rubber and other compounds for bonding to use steel with natural as well as synthetic rubber. Also binding layers made of chlorinated Rubber alone or in combination with rubber hydrochloride were used for one more or more less good adhesion mainly of synthetic elastomers to metal. For the purpose but mixtures of degraded chlorinated rubber and polydichlorobutadiene or mixtures can also be used rubber and chlorinated butadiene-styrene rubber can be used. There were too copolymers of conjugated dienes with chlorinated elastomers have already been used. Graft polymers were also used natural or synthetic elastomer with acrylic acid derivatives and chlorinated rubber together with vinyl pyridine compounds.

However, these previously used binders were not generally useful.

A new rubber-metal binder must now have the following properties:

a) Universal usability. The same agent must be used for different types of polymers, for example Natural rubber, butadiene-styrene rubber, oil-extended butadiene-styrene rubber, as well its blends with polybutadiene and for chloroprene rubber and butadiene-acrylonitrile rubber be usable.

b) The bonds achieved must have high strength.

c) The bond obtained must also withstand prolonged dynamic and static loads.

d) The binder must also be used if the treated metal parts before Vulcanization must be stored under the influence of moisture for a long time.

There has now been a method for firmly bonding metals or metal alloys to natural or synthetic rubber by applying adhesive solutions containing copolymers of aliphatic dienes and vinyl pyridine, polychloroprene, chlorinated rubber and carbon black to the cleaned metal surfaces and / or vulcanizable rubber surfaces, evaporating the solvent , Bonding of metal and rubber and heating Process for firmly bonding metals
or metal alloys to natural or
synthetic rubber

Applicant:

Paint factories Bayer Aktiengesellschaft,
5090 Leverkusen

Named as inventor:

Dr. Franz von Spulak, 5090 Leverkusen

of the composite body found at vulcanization temperatures in which adhesive solutions are used, which is a mixture of 20 to 40 percent by weight of a terpolymer of butadiene as solids, 2-vinyl pyridine and styrene, 10 to 30 weight percent polychloroprene ,. 20 to 40 percent by weight chlorinated rubber, 20 to 50 percent by weight of carbon black and 1 to 50 percent by weight of a methyl methacrylate-butadiene copolymer contain.

This rubber-metal binder fulfills the requirements mentioned under a) to d). The known Rubber-metal binder based on triphenylmethane triisocyanate, on the other hand, can only be used for Mixtures of natural rubber, chloroprene rubber and butadiene-acrylonitrile rubber, but not against it for those made of butadiene-styrene rubber, oil-extended butadiene-styrene rubber or blends with polybutadiene.

This is also the case for the mixtures that can be bonded with this metal adhesive Strength level on average only about 60 to 70% of that to be used according to the invention Binder attainable levels. The heat resistance of the bond with triphenylmethane triisocyanate is although sufficient, it is limited to mixtures with natural rubber, butadiene-acrylonitrile rubber and chloroprene rubber and shows a low level here too.

Metal parts treated with triphenylmethane triisocyanate solutions can, above all, be affected by higher humidity can only be stored for a few hours before vulcanization, otherwise it will sink the binding values strongly decrease.

The polymers used for the binder mixture used in the present invention are as follows characterizes:

809 518/706

A terpolymer from butadiene, 2-vinylpyridine and styrene is particularly suitable as the terpolymer 67.9 parts by weight of butadiene, 22.5 parts by weight of styrene and 9.6 parts by weight of 2-vinylpyridine, where the vinyl pyridine can contain 2 to 2.5% PicoHn. The copolymers of these compounds are in generally in aqueous emulsion with resin acid as emulsifier at 45 to 80 ° C.

Polychloroprene is to be understood as meaning a polymer which is predominantly, preferably about 90 to 95%> consists of 1,4-trans-chloroprene monomer units and z. B. in aqueous emulsion at polymerization temperatures from 5 to 20 ° C. These polymers show a strong tendency to crystallize.

The chlorinated rubber to be used is made by chlorinating chemically degraded natural rubber, z. B. in a solution of carbon tetrachloride with the addition of stabilizers such as epoxides, obtain. A product with 66% chlorine content is preferably used.

The methyl methacrylate - butadiene copolymer which is used according to the invention, is preferably a copolymer of methyl methacrylate and butadiene in a molar ratio of 1: 1. This polymer is z. B. by copolymerization of the components in emulsion at about 5 ° C in the presence an emulsifier. For isolation, the product can be extracted from the emulsion, e.g. B. precipitate with table salt and then wash and dry.

Aromatic hydrocarbons, in particular Toluene and methyl ethyl ketone are used. The solutions should be 5 to 10 percent by weight solids contain. To reduce the viscosity of these solutions, about 5 to 10 percent by weight, based on the finished solution, trichlorethylene or ethyl alcohol can be added.

Among natural or synthetic elastomers, their mixtures for rubber-metal bonds Are to be understood:

Natural rubber or synthetic rubbers of various types, especially copolymers Butadiene and styrene, butadiene and acrylonitrile, polychloroprene and polybutadiene.

Metals in the context of this invention are in particular the most varied types of steel, but also zinc, Copper, aluminum, magnesium and their alloys, such as brass, bronze, gunmetal, duralumin, Bondur, electron.

The creation of the bond between the metals and the mixtures of natural or synthetic Elastomers can be made so that the metal surface to be bonded is cleaned with a 15% strength Brushed solution of chlorinated rubber in toluene and dried for 30 to 60 minutes at room temperature will. A solution of the binder to be used according to the invention is then sprayed over. Afterward is covered with the preformed mixture to be bound and placed in molds under pressure in the Vulcanized press.

The vulcanization takes place depending on the mixture composition for the natural or synthetic Elastomers at temperatures of about 110 to 180 ° C, the vulcanization times depending on the type and Align the thickness of the parts to be bound. They are usually between 3 minutes and 2 hours.

It is also possible in some cases to mix the binder to be used according to the invention with the 15 ° / ₀ by weight chlorinated rubber solution to give about 1 used on 1 part by weight binder solution to 5 parts by weight of chlorinated rubber solution. It is also possible to increase the content of chlorinated rubber in the binder solution to two to five times (by weight). When using such a solution, it is not necessary to pretreat the cleaned metal surfaces with a chlorinated rubber solution.

The rubber-metal bond strength is determined on cylindrical rubber-metal parts in which the cylinder diameter is 30 mm, the height of the rubber part is 30 mm and the height of the two metal parts is 15 mm each. Specially designed vulcanization molds are used in which the ejection takes place perpendicular to the bonding surfaces. Ao threads are cut into the metal surfaces opposite the binding surfaces, into which brackets are screwed in order to ensure even clamping and tearing in the tearing machine. The feed rate is 50 mm / minute. The polymer mixtures to be used as adhesion promoters according to the invention can be used per se without the addition of customary rubber auxiliaries. On the other hand, the strength of the bonds achieved is sometimes even beneficial if the solutions or emulsions of the polymer mixtures contain certain amounts of vulcanizing agents, such as sulfur, sulfur-yielding substances, zinc oxide, accelerators, the diphenylnitrosamines known as regulators, organic peroxides, polyisocyanates as well as anti-aging agents, plasticizers and Fillers are added.

The claimed method is of particular importance for the connection of steel with mixtures of Butadiene-styrene copolymers, natural rubber, butadiene-acrylonitrile copolymers and polybutadiene and chloroprene polymers.

Not only are high binding values achieved, but the binding is also particularly resistant against the influence of high temperatures, even under dynamic stress. Such Bonds are hardly or not at all achieved with the substances mentioned at the beginning.

The binding solutions can also be used after standing for a long time without being in the solutions Show settlements or the bonds made with them are impaired. This will be done with the specified and previously known adhesives not achieved.

example 1

The following mixture was produced on the mixing roller:

100.0 parts by weight of a terpolymer of butadiene, 2-vinylpyridine and styrene,

40.0 parts by weight of polychloroprene,
10.0 parts by weight of a copolymer of methyl methacrylate and butadiene,

80.0 parts by weight of chlorinated rubber,
20.0 parts by weight of medium-processable sewer black, 40.0 parts by weight of half-reinforcing furnace black,

290.0 parts by weight.

The mixture was dissolved in toluene in a weight ratio of 1: 8 and the solution with 5% ethyl alcohol offset. Metal blocks made of 00 steel were used in the dimensions described. Was bound a mixture of the following composition:

100.0 parts by weight ßutadiene-styrene rubber, 48.0 parts by weight very highly abrasion-resistant furnace carbon black,

5.0 parts by weight of zinc oxide, 8.0 parts by weight of aromatic oil, 2.0 parts by weight of coumarone resin, 0.6 parts by weight paraffin,

1.5 parts by weight of stearic acid, 1.0 part by weight of phenyl-a-naphthylamine, 1.0 part by weight of N'-phenyl-N'-cyclohexyl-

p-phenylenediamine, 1.8 parts by weight of sulfur, 1.25 parts by weight of benzothiazyl-2-cyclohexyl-

sulfenamide, ao 0.15 parts by weight tetramethylthiurammono-

sulfide,

170.30 parts by weight.

25th

The metal surfaces to be bonded were blasted with quartz sand and the first line was a 15% solution of chlorinated rubber in toluene applied. After a drying time of 30 minutes, a second line became the mentioned binding solution applied. After a further 30 minutes, the was used according to the invention Applied binder mixture and the rubber in molds under pressure for 40 minutes at 152 ° C vulcanized.

The vulcanized rubber-metal parts were torn after storage for 24 hours at a rate of 50 mm / minute. Rubber-to-metal adhesion values of 125 kg / cm ^{2 were} achieved.

B e i s ρ i e 1 2

The same binding solutions were used as in Example 1 and otherwise the same procedure was used, only the mixture to be bound had the following composition:

100.0 parts by weight of butadiene-styrene mixed poly-

merisate containing 50 parts by weight of oil per 100 parts by weight of rubber, 45.0 parts by weight of medium-processable sewer carbon black, 7.5 parts by weight zinc oxide,

5.0 parts by weight of coumarone resin, 1.7 parts by weight of sulfur,

1.2 parts by weight of benzothiazyl-2-cyclohexyl-

sulfenamide,

0.8 parts by weight phenyl / 5-naphthylamine,

161.2 parts by weight.

Vulcanization took place for 40 minutes at 152 ° C. The bond strength achieved was 96 kg / cm ^a . This value is also not achieved with the adhesives mentioned at the beginning.

_{Example3 6s}

The procedure was as in Example 1. A natural rubber mixture of the following composition was bound:

100.0 parts by weight of smoked sheets, 44.0 parts by weight of medium-processable sewer soot, 8.0 parts by weight of zinc oxide,

4.0 parts by weight of aromatic oil as a plasticizer,

4.0 parts by weight of stearic acid, 3.0 parts by weight of sulfur,

1.0 part by weight of 2-mercaptobenzothiazole,

1.5 parts by weight of N-phenyl-N'-isopropylp-phenylenediamine,

165.5 parts by weight.

The vulcanization was carried out for 30 minutes at 143 ⁰ C. It has a bond strength of 112 kg / cm ² found. This exceeds the peak values found for this quality with other adhesives.

Example 4

The procedure was as in Example 1. However, the following mixture was used as the mixture to be bound:

100.0 parts by weight of butadiene-acrylonitrile mixed

polymer (acrylonitrile content: 33%),

3.0 parts by weight zinc oxide,
40.0 parts by weight of semi-reinforcing furnace black, 15.0 parts by weight of highly abrasion-resistant furnace black, 1.0 part by weight of stearic acid, 3.0 parts by weight of aromatic oil, 1.0 part by weight of rosin, 1.8 parts by weight of sulfur,

1.2 parts by weight of benzothiazyl-2-cyclohexylsulfenamide,

166.0 parts by weight.

Vulcanization: 30 minutes at 152 ° C. A bond strength of 82 kg / cm ^{2 was} achieved.

Example 5

The procedure was as in Example 1. However, the following mixture was used as the mixture to be bound:

Parts by weight of polybutadiene, parts by weight of smoked sheets, 4 parts by weight of zinc oxide,
Parts by weight of very highly abrasion-resistant furnace black, 1 part by weight of phenyl - /? - naphthylamine, 1 part by weight of N-phenyl-N-isopropyl-

p-phenylenediamine, 3 parts by weight of aromatic oil as plasticizer,

3 parts by weight synthetic resin,

1.5 parts by weight of stearic acid,

1.6 parts by weight of benzothiazyl-2-sulfenmorpholide, 0.3 parts by weight of tetramethylthiuram disulfide, 1.0 part by weight plasticizer.

Vulcanization: 30 minutes at 152 ° C. A bond strength of 99 kg / cm ^{2 was} achieved.

Example 6

The procedure is as in Example 1, with the only difference that the primer is made of 15% chlorinated rubber solution not applicable, but instead of 80 parts by weight of chlorinated rubber in the binder solution 360 parts by weight of chlorinated rubber are incorporated.

Claims (1)

With this so-called one-part process, a bond strength of 78 kg / cm ^{2 is} achieved. Example 7 A number of rubber-metal parts, which are produced according to the procedure of Example 1 with the aid of steel blocks of type 00 , are stored at different temperatures for 8 days and also torn at these temperatures, namely at 20, 50, 70, 100, 120 and 150 ⁰ C Binding strengths of 117, 99, 83, 66, 52 and 43 kg / cm ^{2 are} found. These values exceed the results with other commercially available binders and prove the high heat resistance of the rubber-metal bond achieved. 15th Claim: Process for firmly bonding metals or metal alloys to natural or synthetic rubber by applying adhesive solutions containing copolymers of aliphatic dienes and vinyl pyridine, polychloroprene, chlorinated rubber and carbon black to the cleaned metal surfaces and / or vulcanizable rubber surfaces, evaporation of the solvent, bonding of metal and rubber and heating of the composite body to vulcanization temperatures, characterized in that adhesive solutions are used which, as solids, contain a mixture of 20 to 40 percent by weight of a terpolymer of butadiene, 2- vinylpyridine and styrene, 10 to 30 percent by weight of polychloroprene, 20 to 40 percent by weight of chlorinated rubber, Contain 20 to 50 percent by weight of carbon black and 1 to 50 percent by weight of a methyl methacrylate-butadiene copolymer. Considered publications:
French Patent No. 1,297,490. A test report was displayed when the registration was announced. 809 518/706 3.68 © Bundesdruckerei Berlin