DE1292376B - Process for joining polyurethane layers with natural rubber or synthetic rubber layers - Google Patents

Description

The invention relates to a method for joining polyurethane layers with natural rubber or synthetic rubber layers with the help of adhesive solutions, containing organic isocyanates and elastomeric film-forming substances, under pressure and warmth.

It is known that polyurethane elastomers have excellent durability against wear and tear, sunlight, ozone and the like the manufacture of objects such as vehicle tires, shoe soles and heels or the like

In many cases, you only create an external, exposed one Polyurethane elastomer layer, which with the base body made of natural or synthetic rubber connected is. For example, in tire manufacture, the tread is made from Polyurethane elastomers and the shell made of natural or synthetic rubber.

The difficulty in making a satisfactory bond between polyurethane elastomers and natural or synthetic rubber is well known. Contain the most effective binders and adhesives proposed so far for this purpose Isocyanates, however, is the adhesive strength achieved even with these binders in most cases not as high as desired. You already have isocyanates proposed for joining synthetic rubber to other, non-metallic bodies. Better adhesion would also be desirable here.

The invention was based on the object of a method for connecting of polyurethane layers with natural rubber or synthetic rubber to find that causes better adhesive strength between the layers to be connected than this is possible with the adhesives according to the state of the art. The new procedure is characterized in that adhesive solutions are used which a) isocyanates in amounts of at least 1 percent by weight isocyanate groups and b) aromatic nitroso compounds in amounts of at least 0.9 percent by weight of nitroso groups, each based on the solids content of the adhesive solutions.

With this method, rubber with such adhesive strength can be produced to a solid, non-metallic base, e.g. B. of polyurethane elastomers or -Resins, stick on, that when used, more likely to tear in one of the two bodies than occurs in the adhesive layer.

The polyurethane elastomers and polyurethane resins are known isocyanate-extended polyesters. They are made in such a way that an isocyanate compound, usually a diisocyanate, with a comparatively high molecular weight polyester is made to react. In the reaction between the isocyanate and the polyester urethanes are formed. Usually when joining a polyurethane elastomer or polyurethane resin to another body with the application of heat and pressure the polyurethane body used according to the invention in the non-vulcanized state.

Natural rubber is used as the type of rubber for the present invention and unsaturated synthetic rubbers such as polybutadiene, butadiene-styrene rubber, Butadiene - acrylonitrile - rubber, rubbery copolymers of butadiene and vinyl pyridine, rubber-like copolymers of chloroprene and ethylenically unsaturated compounds, Polychloroprene, butyl rubber or the like can be considered.

As the isocyanate, any organic compound with one or more Isocyanate groups are used, since experience has shown that the isocyanate group is the effective site in the binding process, while the rest of the molecule compares is unimportant. There are a variety of different isocyanates that can be used, starting with from simple organic monoisocyanates to polymers with isocyanate groups. Examples of isocyanate compounds include: the alkyl isocyanates, such as Ethyl isocyanate and octadecyl isocyanate, the aryl isocyanates such as phenyl isocyanate and α-naphthyl isocyanate, the diisocyanates, e.g. B. the polymethylene diisocyanates, such as hexamethylene diisocyanate, aromatic diisocyanates such as p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, Toluene diisocyanate, 4,4'-diphenylene methane diisocyanate, benzidine diisocyanate; the corresponding Tri-, tetra- and polyisocyanates, e.g. B. 1,2,4-benzene triisocyanate, triphenylmethane triisocyanate or polymers with isocyanate groups, such as phosgenated aniline-aldehyde resins, such as them z. In U.S. Patent 2,683,730.

According to the invention is used as an adhesive together with the isocyanate Nitroso compound used.

The nitroso compound used generally consists of one aromatic compound with at least one bonded directly to a ring carbon atom Nitroso group. If, as preferred, two or more nitroso groups are present, they are bound to non-adjacent ring carbon atoms. The aromatic group can be unsubstituted except for the nitroso group or groups or other substituents have, in which one or more of the nuclear hydrogen atoms are substituted by alkyl, Alkoxy, cycloalkyl, aryl, arylalkyl, arylamine, arylnitrosamine, halogen, or the like Groups can be replaced. Since the nitroso group is the most effective with regard to the invention Is part of the nitroso compound, has the presence of such substituents on the aromatic nucleus only minor influence on the effectiveness of the nitroso compound, and to the best of our knowledge, there is no limit to the nature of the substituents. So much for aromatic nitroso compounds, nitrosobenzenes or nitrosonaphthalenes Reference is made to include both unsubstituted and substituted Nitroso compounds be understood, unless otherwise specified. There according to literature hydroxy-substituted, aromatic nitroso compounds with of the nitroso group with the formation of: Oximes react, they do not become the nitroso compounds defined here calculated.

The preferred aromatic nitroso compounds include the nitrosobenzenes and naphthalenes and especially the dinitroso compounds, especially the meta- or para-dinitrosobenzenes and -naphthalenes.

When carrying out the method according to the invention, a Adhesive containing an isocyanate and a nitroso compound between the Surfaces to be connected are inserted. The isocyanate must be present in the intermediate phase of adhesion at least at the interface between the polyurethane layer and the intermediate adhesive phase and the nitroso compound at least at the interface between the rubber and the intermediate adhesive phase.

Such an intermediate phase of adhesion is usually achieved by applying an adhesive mixture containing the isocyanate and the nitroso compound is achieved, but can also be effected by applying their components separately.

Furthermore, the adhesive must also be an elastomeric film-forming one Contain substance. In this case, the adhesive stick can be made from a preformed Sheet that are isocyanate, nitroso compound and elastomeric film-forming Contains substance. The exact type of procedure does not matter, be preferred however, the isocyanate and the nitroso compound and the elastomeric film-forming substance applied in intimate mixture.

The elastomeric film-forming substance serves as a carrier for the isocyanate or the nitroso compound, or both. To this end, everyone is organic elastomer film-forming substance suitable, but which have a high internal strength should. Your choice also depends on the type of composite structure and its later Use from. For example, for a structure that is supposed to be flexible, one becomes a Use flexible, film-forming substance. Suitable examples of elastomers are the polymers and copolymers of ethylenically unsaturated substances such as vinyl polymers and copolymers and their non-halogenated derivatives, polymers of conjugated dienes and their post-halogenated products. Particularly suitable film-forming substances are polychloroprene, poly-2,3, dichlorobutadiene (1,3) and post-brominated poly-2,3-dichlorobutadiene (1,3), especially those with a bromine content between about 7.5 and 42, preferably between about 15 and 36 mole percent.

One of the main components of the intermediate adhesive phase can also be used be a component of the elastomeric film-forming substance, such as polyurethane elastomers or polyurethane resins, d. H. an isocyanate-extended polyester.

The intermediate phase of adhesion can also be used for any other purpose contain useful substances. For example, together with the isocyanate also catalysts, e.g. B. of reactive hydrogen free, tertiary amines, for the purpose Acceleration of the isocyanate reaction can be added.

The ratio of the main components of the adhesive to one another can vary within wide limits. The isocyanate group effective for the isocyanate Experience has shown that at least in the border area to polyurethane in a quantity of at least 10 / o, calculated on the weight of the solids in the intermediate adhesion phase, to be available. The proportion of isocyanate used can be so high that the Isocyanate groups - of course, to a certain extent depending on the selected isocyanate - at least in the area adjacent to the polyurethane about 50 to 600/0, based on the weight of solids calculated in the interim phase of detention. Preferably so much isocyanate should be used be used that about 2 to 25 percent by weight isocyanate groups on the specified Basis are in place, with the aim of achieving particularly good adhesion higher temperatures at least about 5% isocyanate groups on the given basis are recommended.

In the case of the nitroso compound, as in the case of isocyanate, there is the nitroso group itself the effect factor, and it depends on how many nitroso groups at least at the interface between the natural or. Synthetic rubber and the intermediate adhesive phase available. Experience has shown that as much nitroso compound should be used as that the nitroso groups at least in the border area to rubber at least 0.4010, calculated on the weight of solids in the intermediate adhesion phase. The amount the applied nitroso compound can at least in the border area to natural rubber or synthetic rubber layer up to 42% by weight of solids in the intermediate adhesive phase calculated, make up. The preferred amount of nitroso compound applied corresponds to preferably a nitroso group content between 0.9 to 22 percent by weight in the above Senses.

Regarding the attachment of the intermediate detention phase described earlier in one or the other in both of the surfaces to be united it comes from the general From the point of view of the invention, not the special condition of the components at the time of their attachment. One or more of the same components can be applied in solid, finely divided or preferably in liquid form. In the latter case, for example, a solvent for a component or several of the same can be used. Preferably at the time of Attachment of at least one component in a liquid state. The isocyanate and in particular the nitroso compounds are often suspended in the solution.

The solvent used must be volatile enough to be excessive long drying times can be avoided. Preferred solvents include aromatic hydrocarbons, such as benzene, toluene, xylene or the like, which are chlorinated aromatic hydrocarbons, such as monochlorobenzene, dichlorobenzene or the like, ketones, such as methyl ethyl ketone or the like, esters such as ethyl acetate or the like. Alcohols are not used because their hydroxyl groups react with the isocyanate.

After the ingredients are applied and all solvents have evaporated the surfaces to be joined are brought together, and the composite structure is heated to vulcanize the rubber. Like the professional is known, the exact duration and temperature of vulcanization depend on nature and composition of the rubber mixture and the constituents of the adhesive phase. In general, the vulcanization temperature is between 121 and 1770 C and the duration between about 20 and about 100 minutes.

Example 1 A freshly mixed adhesive composed of 100 parts of polyurethane elastomers, 50 parts of polyisocyanate produced by phosgenating aniline-formaldehyde resin, 25 parts of p-nitrosodiphenylamine and 567 parts of methyl ethyl ketone was applied to the surface a freshly rolled polyurethane elastomer mixture containing a conventional vulcanizing agent applied and allowed to dry. A slab was then freshly rolled out unvulcanized rubber mixture onto the adhesive-coated polyurethane elastomer surface upset. The rubber mixture consisted of 100 parts of butadiene-styrene rubber, 50 parts of highly abrasion-resistant furnace black, 5 parts of zinc oxide, 1 part of stearic acid, 1.75 Parts of sulfur and 1.25 parts N-Cyclohexyl-2-benzthiazylsulfenamide. The composite was vulcanized under pressure for 60 minutes at 134 ° C, then off taken from the mold and vulcanized in an oven at 70 ° C for 24 hours.

The bond achieved here is so good that the composite body neither could still be separated at 930 C at room temperature without the polyurethane layer tear down.

Example 2 A freshly mixed adhesive composed of 100 parts of polyurethane elastomers, 50 parts polyisocyanate made by phosgenating aniline-formaldehyde resin, 10 parts of N'4-Dinitrosodiphenylamin and 567 parts of methyl ethyl ketone was on a freshly rolled polyurethane elastomer containing a conventional vulcanization system brushed on and left to dry. This was followed by a sheet of freshly rolled out applied unvulcanized natural rubber mixture. The mix consisted of 100 Parts smoked sheets, 50 parts highly abrasion-resistant furnace soot, 15 parts zinc oxide, 1 Part of stearic acid, 2 parts of sulfur, 1.5 parts of dibenzothiazyl disulfide and 2 parts Zinc methyl dithiocarbamate. The joint was pressurized for 60 minutes at 1340 C vulcanized, then removed from the mold and post-vulcanized at 70 ° C for 24 hours. The test of the composite piece showed a firm bond, so that when you separate the Composite body, tearing of the rubber layer was observed.

Example 3 A freshly mixed adhesive composed of 100 parts of polyurethane elastomers, 50 parts polyisocyanate made by phosgenating aniline-formaldehyde resin, 25 parts of p-dinitrosobenzene and 567 parts of methyl ethyl ketone was applied to the surface a freshly rolled polyurethane elastomer mixture containing a conventional vulcanization system applied and allowed to dry. A slab was then freshly rolled out unvulcanized carriage mix applied to the coated surface. the The rubber mixture consisted of 100 parts of butadiene-styrene rubber, 50 parts of highly abrasion-resistant Furnace black, 5 parts of zinc oxide, 1 part of stearic acid, 175 parts of sulfur and 1.25 parts N-Cyclohexyl-2-benzthiazylsulfenamide. The joint was under pressure for 60 minutes vulcanized at 134 ° C, then removed from the mold and post-vulcanized at 700 C for 24 hours. The bond was so good that the composite was neither at room temperature nor at 93 ° C could be separated from each other without tearing the polyurethane layer Example 4 Example 3 was repeated, but the rubber mixture had the following Composition: 100 parts smoked sheets, 50 parts highly abrasion-resistant furnace black, 15 Parts of zinc oxide, 1 part of stearic acid, 2 parts of sulfur, 1.5 parts of dibenzthiadisulfide and 0.2 parts of zinc dimethyl dithiocarbamate. It got the same strength of the connection as achieved in example 3. Example 5 A freshly mixed adhesive made from 100 Parts of polychloroprene, 50 parts by phosgenating aniline-formaldehyde resin produced polyisocyanate, 25 parts of p-dinitrosobenzene and 567 parts Methyl ethyl ketone was applied to the surface of a freshly rolled, a common vulcanization system containing polyurethane elastomer mixture applied and allowed to dry. A sheet of freshly rolled out unvulcanized natural rubber mixture was then according to the composition mentioned in Example 4, onto the coated polyurethane surface applied and the composite piece under the ratios given in Example 4 vulcanized. When the composite body tore, the polyurethane elastomer tore.

Example 6 A freshly mixed adhesive made from 100 parts of post-brominated Poly-2,3-dichlorobutadiene- (1,3) (about 20 weight percent Br), 25 parts by phosgenation polyisocyanate made from aniline-formaldehyde resin, 25 parts p-dinitrosobenzene and 400 parts of monochlorobenzene was applied to the surface of a freshly rolled, a conventional vulcanizing agent containing polyurethane rubber applied and left to dry. A sheet of unvulcanized rubber compound was then according to Example 1, applied to the coated polyurethane surface. That Composite piece was vulcanized under the conditions given in Example 1. The bond achieved here is so good that the composite body is neither at room temperature could still be separated at 93 ° C without tearing the polyurethane layer.

Example 7 A freshly mixed adhesive according to example 6, was applied to the surface of a freshly rolled, common vulcanizing agent containing polyurethane elastomers applied. As a result, a slab was unvulcanized Natural rubber, corresponding to Example 2, on the coated polyurethane surface upset. The composite piece was made under the proportions given in Example 1 vulcanized. The bond achieved in this way was so good that the composite body neither Could still be separated at 93 ° C at room temperature without the polyurethane layer tore.

Example 8 A freshly mixed adhesive made from 100 parts of post-brominated Poly-2,3-dichlorobutadiene (1,3) (about 20 weight percent Br), 25 parts orthotoluidine diisocyanate, 25 parts of p-dinitrosobenzene and 400 parts of monochlorobenzene was applied to the surface of a freshly rolled polyurethane elastomer containing conventional vulcanizing agents applied and allowed to dry. A panel was then made from an unvulcanized one Rubber mixture, corresponding to Example 1, on the coated polyurethane surface upset. The composite was vulcanized under pressure for 60 minutes at 134 ° C, then removed from the mold and post-vulcanized in an oven at 70 ° C for 24 hours. The bond achieved here was so good that the composite body did not separate could without tearing the polyurethane layer.

Example 9 A freshly mixed adhesive according to Example 8 was used onto the surface of a freshly rolled, one common vulcanizing agent containing polyurethane elastomer mixture applied and allowed to dry. Thereupon a sheet of unvulcanized natural rubber mixture was made, accordingly Example 2 applied to the coated polyurethane surface. The composite piece was vulcanized under pressure at 1340 C for 60 minutes, then removed from the mold and post-vulcanized in an oven at 700 ° C. for 24 hours. The bond achieved in this way was so good that the composite did not separate either at room temperature or at 930.degree could be without tearing the polyurethane layer.

Example 10 A freshly mixed adhesive composed of 100 parts of polychloroprene, 25 parts of orthotoluidine diisocyanate, 25 parts of p-dinitrosobenzene and 567 parts of methyl ethyl ketone has been rolled onto the surface of a freshly rolled, a common vulcanizing agent containing polyurethane elastomers applied and allowed to dry. Thereupon a sheet of freshly rolled out unvulcanized rubber mixture was applied. The mixture consisted of butadiene-styrene rubber (100 parts), 40 parts of sewer black, 5 parts of zinc oxide, 2 parts of sulfur, 2 parts of dibenzothiazyl disulfide. The composite piece was vulcanized under pressure at 134 ° C. for 60 minutes, then removed from the mold and post-vulcanized in an oven at 700 ° C. for 24 hours. The bond achieved in this way was so good that the composite could not be separated without removing the polyurethane layer tore.

Example 11 A freshly mixed 100 part common adhesive Polyurethane elastomers, 25 parts of orthotoluidine diisocyanate, 25 parts of p-dinitrosobenzene and 567 parts of methyl ethyl ketone was applied to the surface of a freshly rolled, a conventional vulcanizing agent containing polyurethane elastomers applied and left to dry. Then a sheet of freshly rolled unvulcanized ones was made Natural rubber mixture according to Example 2 on the adhesive-coated polyurethane surface upset.

The composite was vulcanized under pressure for 60 minutes at 134 ° C, then removed from the mold and post-vulcanized at 700 ° C. for 24 hours.

The bond achieved in this way was so good that the composite body neither could still be separated at 930 C at room temperature without the polyurethane layer tore.

Example 12 A freshly mixed 100 part common adhesive Polyurethane elastomers, 50 parts by phosgenating aniline-formaldehyde resin produced polyisocyanate, 25 parts of 2,5-dinitroso-p-cymene and 567 parts of methyl ethyl ketone has been rolled onto the surface of a freshly rolled, a common vulcanizing agent containing polyurethane elastomers applied. Thereupon a board became fresh rolled out unvulcanized rubber mixture according to Example 1 onto the adhesive-coated Polyurethane surface applied. The joint was under pressure for 60 minutes vulcanized at 134 ° C, then removed from the mold and the one in an oven post-vulcanized at 70 ° C. The bond achieved in this way was so good that the composite body could not be separated either at room temperature or at 930 C without the polyurethane layer tore.

Example 13 A freshly mixed 100 part common adhesive Polyurethane elastomers, 50 parts by phosgenating aniline-formaldehyde resin produced polyisocyanate, 50 parts of 2,4-dinitrosonaphthalene and 567 parts of methyl ethyl ketone has been rolled onto the surface of a freshly rolled, a common vulcanizing agent containing polyurethane elastomers applied. Thereupon a board became fresh rolled out unvulcanized natural rubber mixture according to Example 2 on the coated Polyurethane surface applied. The joint was under pressure for 60 minutes vulcanized at 134 ° C, then removed from the mold and placed in an oven for 24 hours post-vulcanized at 70 ° C. The test of the connecting piece showed a strong bond, so that when the composite bodies are separated, tearing of the rubber layer is observed became.

Example 14 A freshly mixed 100 part common adhesive Polyurethane elastomers, 50 parts by phosgenation of aniline-formaldehyde resin produced polyisocyanate, 50 parts of p-dinitrosobenzene and 567 parts of methyl ethyl ketone has been rolled onto the surface of a freshly rolled, a common vulcanizing agent containing polyurethane elastomers applied and allowed to dry. Thereupon became a sheet of freshly rolled out unvulcanized polychloroprene rubber mixture upset. The mixture consisted of 100 parts of polychloroprene, 0.5 part of stearic acid, 4 parts of magnesium oxide, 2 parts of phenyl-ß-naphthylamine, 50 parts of sewer black, 5 parts Zinc oxide and 0.5 part of 2-mercaptoimidazoline on the adhesive-coated polyurethane surface applied and vulcanized under the conditions specified in Example 8. The bond achieved here was so good that the composite body did not separate could without tearing the polyurethane layer.

Claims (1)

Claim: Method for joining polyurethane layers with natural rubber or synthetic rubber layers with the help of adhesive solutions, containing organic isocyanates and elastomeric film-forming substances, under pressure and heat, characterized in that such adhesive solutions are used that a) Isocyanates in amounts of at least 1 percent by weight of isocyanate groups and b) aromatic Nitroso compounds in amounts of at least 0.9 percent by weight of nitroso groups, each based on the solids content of the adhesive solutions.