AU631492B2

AU631492B2 - Composite material and composite structures as well as methods for producing the same, and the use thereof

Info

Publication number: AU631492B2
Application number: AU74215/91A
Authority: AU
Inventors: Kai Metzger; Georg Spindler
Original assignee: Stahlgruber Otto Gruber GmbH and Co
Current assignee: Stahlgruber Otto Gruber GmbH and Co
Priority date: 1990-04-06
Filing date: 1991-04-08
Publication date: 1992-11-26
Anticipated expiration: 2011-04-08
Also published as: ZA912534B; EP0450634B1; AU7421591A; EP0450634A2; ES2114863T3; DK0450634T3; EP0450634A3; DE59108952D1; ATE164113T1; DE9108269U1; GR3026469T3

Abstract

The invention relates to a composite material in the form of a flat material for coating substrates (7), which contains an underlayer (2) of a prevulcanised, cold-vulcanisable chloroprene rubber which optionally contains a mineral filler, and a top layer (1) of a polyurethane elastomer which is bonded to the underlayer (2) via a binder layer (3) and has been produced by applying a pourable polyurethane system to the underlayer (2) coated with a solvent-free reactive adhesive. The invention furthermore relates to corresponding composite elements which comprise this composite material and a substrate (7) which is bonded to the underlayer (2) of the composite material. The composite material is particularly suitable for the corrosion- or wear-inhibiting coating of metal surfaces. <IMAGE>

Description

r COMMONWEALTH OFA 4 PATENTS ACT 1952 COMPLETE SPECIFICATION NAME ADDRESS OF APPLICANT: STAHLGRUBER Otto Einsteinstrasse 130 D-8000 Miinchen Germany Gruber GmbH Co.

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(a NAME(S) OF INVENTOR(S): Kai METZGER Georg SPINDLER ADDRESS FOR SERVICE: DAVIES COLLISON Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: Composite material and composite structures as well as methods same, and the use thereof for producing the 0 The following statement is a full description of this invention, including the best method of performing it known to me/us:a* *c*V *V M 026C -la- The present invention relates to a composite material in the form of a flat material for coating in particular substrates subject to wear and/or corrosion, to respective composite structures as well as to methods for producing the same, and to the use of said composite material.

The composite material according to the invention comprises o. a bottom loyer made of a chloroprene rubber, the underside of which is provided for applying onto tha substrate to be coated, and a top layer consisting of a polyurethane and connected to the upper side of the bottom layer by mean- of a bonding layer.

s r Linings and coatings of rubber mixtures for the protection against corrosion and for reducing wear and tear of machine parts and structural members subjected to high abrasive forces, and for the protection of construction elements, foundations and the like have long been known, which linings and coatings are applied onto the surface of the respective substrates as sheets and fixedly bonded thereto, using suitable means. The most frequently used and most convenient type of connecting is adhesive bonding, covering large areas. To this end, the surface of the metal part to be protected, for instance, is cleaned and roughened, for example by means of sand-blasting. Subsequently, a reactive binding agent, for example on the basis of a chlorinated rubber having reactive groups, is applied onto the pre-treated surface in one or several layers. Onto those, a sheet consisting of a rubber elastomer is applied, which, at its bondinog side, may comprise a thin layer of a I li r i ii pro-vulcani.zed rubber. Such coatings bring about the advantage of a strong and permanent bond between the wearand-tear-free rubber layer and the substrate, in particullar steel, and also in the case of varying mechanical loads.

Because of their variably settable characteristics polyurethanes, already for some time, have been employed as relatively highly wear- and corrosion-resistant coating and lining materials in the form of sheets, films or other shaped articles. Although this material, whose hardness and elasticity may be set via the degree of cross-linking and optionally a plasticizer addition, meets the requirements with respect to protection against wear and corrosion, there are problems when directly applying it onto the metal ,substrates in as much as a sufficiently firm and permanent adhesive bond between metal substrates and a polyurethane S layer cannot be obtained. In addition, it is indispensable in order to obtain a firm bond of the polyurethane with a metal substrate to roughen the polyurethane layer evenly prior to application of the' binding agent, which in the case of large-size flat materia]s is considerably more difficult to achieve than with the conventional rubber sheets.

i From DE-A-28 30 344 composite structures of a metal substrate and a coating firmely bonded thereto are known, S' which coating consists of a bottom layer made up of a plurality of alternating layers consisting of hard rubber and soft rubber, and of a top layer of a thermoplast or a duroplast. The first layer of the bottom layer which is to be bonded to the substrate, in this ;onnection, may consist of a self-vulcanizing chloroprene rubber. The multi-layer structure serves the purpose of preventing, also in the case of varying thermal stress, the composite material from separating from the substrate, or the formation of cracks due to different thermal expansion coefficients. As duroplastic materials for the top layer, inter alia polyurethanes are mentioned. According to this prior art, I II 'II the composite structures are manufactured in a manner such that the individual layers arc applied onto the bare metal surface one after another, using suitable binding agents, optionally followed by vulcanizing. The individual layers are employed as prefabricated sheets, films or webs. It is not possible, though, to achieve a satisfactory connection between a chloroprene rubber as bottom layer and a top layer of a polyurethane applied as flat material through suitable bonding, even if the bottom layer has been roughened previously. A particular difficulty furthermore resides in the fact that the final vulcanization must be carried out in an autoclave which has to be adapted in size to the size of the composite structure to be produced, which in the case of large objects involves considerable investment and operational expenditure.

From DE-A-35 14 864 a method for the production of composite articles from reactive rubber and castable polyurethanes is known, wherein as binding agents certain aromatic nitroso \t .compounds or aromatic sulfenic acid chlorides reactive with double bonds of the rubber and isocyanate groups of the polyurethane system are used. Here, first the unvulcanized i and prevulcanized rubber mixture is pre-treated with the S binding agent, whereupon the polyurethane system is cast S0 thereon. According to this prior art, however, a satisi factory bond between the rubber and polyurethane layers can i he achieved only if the binding agent is applied onto the rubber layer in dissolved state in a polyurethane system, S optionally using an additional solvent, such as methylene chloride, as solubilizer. Another shortcoming is that the P rubber sheet first has to be roughened, then be cleaned with a solvent such as naphtha, and subsequently has to be aired prior to applying the binding agent.

Therefore, the production of composite materials with. a very strong bond between chloroprene rubber and polyurethane in a not too expensive manner and the coating of substrates with these composite materials without requiring the use of an autoclave presented problems which, according to the methods of the prior art, could not be solved satisfactorily.

A requirement accordingly exists for a composite material on the basis of a chloroprene rubber coated with polyurethane, composite structures obtained by coating substrates with this composite material as well as methods for the production thereof by which in a technically simple and at the same economical way bonds of high strength between the chloroprene rubber and the polyurethane as well as between the substrate and the chloroprene rubber may be achieved, the composite materials being applicable directly onto the substrate in a simple way without the use of an autoclave.

According to one aspect of the present invention there is provided a composite material in the form of flat material for coating substrates comprising a bottom layer made of a chloroprene rubber, the underside of which is provided for applying onto a substrate, and a top layer comprising a polyurethane and connected to the upper side of the bottom layer by means of a bonding layer, e 25 characterized in that the bottom layer comprises prevulcanized, coldvulcanizable chloroprene rubber optionally comprising a mineral filler, and 30 the top layer comprises an elastomeric polyurethane optionally comprising a plasticizer, which is made by applying a castable polyurethane system onto the bottom layer coated with a solvent-free reactive binding agent.

According to a second aspect of the present invention there is provided a composite structure on the basis of a r s\ substrate as a base, a bottom layer provided thereon and 920909,dbspec.019,74215.spe,4 1 strongly adhesive thereto, made of a chloroprene rubber, and a top layer made of a polyurethane, strongly adhesive to the bottom layer by means of a bonding layer, characterized in that the bottom layer comprises a prevulcanized, coldvulcanizable chloroprene rubber optionally comprising a mineral filler, and the top layer comprises an elastomeric polyurethane optionally comprising a plasticizer and made by applying a castable polyurethane system onto the bottom layer coated with a solvent-free reactive binding agent.

The composite material which is intended for coating especially substrates subject to wear and/or corrosion and which is present in the form of a flat material, and more particularly in the form of sheets, comprises a bottom layer made of a chloroprene rubber, the underside of which is provided for applying onto the substrate, and a top layer consisting of a polyurethane and connected to S; the upper side of the bottom layer by means of a bonding layer, as is known in the generic terms from the abovementioned DE-A-28 30 344. According to the invention it 25 is characterized in that the bottom layer consists of a prevulcanized, cold-vulcanizable chloroprene rubber, which still has reactive cross-linking centres and optionally comprises a mineral filler, and in that the top layer consists of a polyurethane elastomer, in particular on the basis of a polyester polyol, which optionally comprises a plasticizer. The polyurethane elastomer, in this connection, is evenly applied in a flowable form onto the bottom layer that has been coated with a solvent-free reactive binding agent on the basis of a polyurethane elastomer, and is chemically crosslinked therewith.

It is a particular advantage here, both technically in 920909,dbspcc.019,74215.spe,5 I I I I _I 1 -6terms of processing and economically, that the application of the top layer does not require any *roughening of the bottom layer.

In the method of the invention the bottom layer is provided with a reactive binding agent, whereupon onto the resulting bonding layer the top layer of the polyurethane is provided by applying a castable polyurethane elastomer, in particular a prepolymer, which subsequently is cured.

The hardness and the elasticity properties, respectively, of the polyurethane may be set both by the use of plasticizers and by the choice of the degree of crosslinking within wide ranges.

As binding agent for bonding the chloroprene rubber bottom layer to the top layer of the polyurethane elastomer a solvent-free reactive polyurethane adhesive (binding agent), respectively one that has been made solvent-free, is used, which is reactive with respect to the castable polyurethane system that still comprises free, reactive isocyanate groups and/or hydroxy groups, and with respect to the chloroprene rubber. Such 25 adhesives are known as such to those skilled in the art.

The castable polyurethane system advantageously comprises polyester polyol as polyol component; however other polyols, too, are suited within the scope of the 30 invention.

As polyisocyanate component of the polyurethane system •usual polyisocyanates such as, for example TDI, are suited. The polyurethane system advantageously is used in the form of a corresponding prepolymer.

According to the third aspect of the present invention there is provided a method for producing a composite 920909,dbspec.019,74215.spe,6 it material as defined above, comprising the steps of applying a layer of a binding agent onto a flat material of a chloroprene rubber, applying a layer of a castable polyurethane elastomer onto the flat material of the chloroprene rubber provided with the binding agent, and curing the polyurethane system, characterized in that a prevulcanized, cold-vulcanizable chloroprene rubber optionally comprising a mineral filler, and as binding agent a solvent-free reactive binding agent, particularly on the basis of a polyurethane elastomer, are used.

According to a fourth aspect of the present invention there is provided a method for producing a composite structure as defined above, comprising the steps of applying a layer of a binding agent onto a flat material of a chloroprene rubber, applying a layer of a castable polyurethane elastomer onto the flat material of the chloroprene rubber provided with the binding agent, curing the polyurethane system to produce a composite material and applying the composite material onto a 25 substrate, characterized in that a prevulcanized, cold-vulcanizable chloroprene rubber optionally comprising a mineral filler, and 30 as binding agent a solvent-free reactive binding agent, particularly on the basis of a polyurethane elastomer, are used.

The general method when making up the composite material is that, first, a bottom layer of a prevulcanized, coldvulcanizable chloroprene rubber is provided, onto which, following treatment with the binding agent, the i i i::i 1 i r

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i! i ij b-3 -r r 920909,dbspec.019,74215.spe,7 I II I i -8polyurethane system is applied directly and in the desired thickness, advantageously by pouring, casting or spin-coating. Owing to application of the reactive polyurethane adhesive, which, in case it contains a solvent, is made solvent-free by airing, a chemically modified surface of the chloroprene rubber results which is quasi polyurethane-modified and therefore is optimal for being cross-linked with the cast-on polyurethane system. For coating, the chloroprene rubber of the bottom layer is heated to a temperature above room temperature, ranging from 80 to 15 0 with the polyurethane system advantageously equally being applied in preheated form.

After the top layer has been applied this is followed, if required, by a thermal post-treatment at an elevated temperature in the range of from 80 to 150°C, especially in order to further or completely cross-link the polyurethane.

The possibility provided by the present invention of coating any substrates with the prefabricated composite material, without this requiring an autoclaving step, presents a great technical and industrial advantage over 25 the conventional method, wherein the substrate first is covered with a rubber layer and subsequently, via a bonding layer, with an elastomer layer in the form of a flat material whose firm bonding can be guaranteed only in an autoclave.

The strength of the bond between the chloroprene rubber and the polyurethane, and that without roughening the bottom layer prior to application of the polyurethane, is so high that in the tear test structural rupture occurs within the polyurethane layer, the rupture does not occur in the bonding plane between chloroprene rubber and polyurethane.

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u-; 920909,dbspec.019,7421.sp,8 I f, 8a The bonding of the bottom layer consisting of the chloroprene rubber to a substrate, particularly a metal substrate, is effected by means of a reactive binding agent, preferably a reactive chloroprene adhesive, which is optimally set for the chloroprene rubber layer, coldvulcanization being possible. The chloroprene adhesive has the advantage that a high initial strength is quickly achieved, which allows rapid fixing of the composite material also on considerably inclined or overhanging substrate surfaces. If necessary, the substrate first is treated with a usual primer.

The composite material and corresponding composite structures, respectively, advantageously are so dimensioned that the bottom layer has a thickness in the range of about 0.7 to about 5.0 mm, and preferably of about 3 mm. Analogously, the top layer, according to the invention, advantageously has a thickness in the range of about 2 to about 30 mm, and preferably of about 15 mm.

The composite materials are suited for the coating or lining of a variety of substrates, in particular of very 25 large area substrates, as no autoclaving is required.

They are particularly suited for the coating of substrates consisting of metal, in particular steel, but also for substrates of different materials such as plastic materials, wood, cement or concrete.

30 Accordingly, the composite materials are particularly suited in chemical engineering and in chemical apparatus engineering, as well as for the protection of construction elements such as foundations and the like.

It also is a special advantage in this connection that the composite material canbe applied in a simple way also onto vertical or overhanging surfaces, in particular container inner walls. Due to no roughening of the 9209G9,dbsc.O19j74215.spc,9 -i L

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8b surfaces to be bonded being required any coating operations may accordingly ba performed in considerably shorter periods of time than in the prior art. Owing to the thicknesses of the bottom and top layers being selectable within a wide range, the strength, vibration damping properties and viration resistance of the composite materials may be optimally adapted to the respective application. Accordingly, the composite materials, apart from the bonding layer irrelevant in terms of thickness, also in the case of a two-layer structure exhibit excellent adhesive properties both at the substrate/bottom interface and between the bottom layer and the top layer, even in cases of varying thermal stress.

For lining a metal container, for instance, it is proceeded e.g. in such a manner that to the metal surface a liquid primer is applied, after solidification of which an adhesive, in particular on the basis of a chloroprene rubber, is applied. The same adhesive is applied to the underside of the bottom layer, which need not be roughened to this effect. After putting the composite 25 sheet prepared in this way on the metal surface a fixation through cold-vulcanization takes place in relatively short reaction times, wherein a sufficient initial strength of the bond is achieved quickly, thus facilitating a quick fixation of respective sheets in 30 their predetermined position, without any lateral slipping taking place. Post-vulcanization may be effected through post-heating.

According to an advantageous further development the composite material comprises a

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A a 920909,dbspec.019,74215.5pe, 1 F bottom layer of three superposed layers, with the bottom layer provided for application onto the substrate and, in the case of composite structures, respectively, for being bonded to said substrate so as to firmly adhere thereto, and the upper layer consisting of prevulcanized, cold-vulcanizable chloroprene rubber, which in the case of the composite structures, is correspondingly vulc."nized, and the intermediate layer consisting of vuiicanized chloroprene rubber.

Furthermore, according to another advantageous embodiment Is Sthe inention. an additional layer of chloroprene rubber may be provided, which may consist of one or several layers.

Advantageously, this additional layer consists of three layers and has the same or a similar structure and composition as the above-explained three-layer bottom layer.

The respective layers in each case are bonded to one another with a reactive binding agent, in particular on the basis of a polyurethane elastomer and/or a polychloroprene elastomer.

On the additional layer, in turn, in order to obtain a multi-layer composite structure, one or several layers of the composite material according to the invention may be provided, with what has been said abcve in regard of the respective bondings applying.

According to furthe' embodiments of the method according to the invention one or several of the measures listed below may be taken: Using a castable polyurethane elastomer on the basis of a polyester polyol for the top layer; using a castable polyurethane elastomer for the top layer, comprising a plasticizer; preparing or using a flat material made of the chloroprene rubber as bottom layer in a thicknes, of about 0.7 to mm, and preferably of about 3 mm; flat material of a cloroprene rubber, applying a layer of a castable polyurethane elastomer onto the flat material of the chloroprene rubber provided with the S./2 S i producing the top layer of the polyurethane in a thickness of about 2 to 30 ilim, and preferably of about 15 mm; applying an additional layer consisting of one or more layers made of chlotroprene rubber, preferably consisting of a prevulcanized, cold-vulcanizable chloroprene rubber, onto the top layer; applying an additional layer made of three layers, the two outer layers thereof consisting of a prevulcanized, cold-vulcanizable chloroprene rubber, and the intermediate layer consisting of a vulcanized chloroprene rubber, by bonding one uf the outer layers by means of a reactive binding agent on the basis of a polyurethane elastomer onto the top layer; I applying a composite material as defined above to the additional layer; applying a prefabricated composite material as defined above, particularly in the form of sheets, onto a substrate of a metal, particularly of steel, .lastics, wood, cement or concrete, and particularly onto the inner surface of containers, particularly by bonding, and S...preferably by means of a cold-vulcanizable chloroprene rubber adhesive; applying the castable polyurethane elastomer of the top layer by cast ng, spin-coating or centrifugation; applying the castable poiyuirethane elastomer of the top layer at a temperature above its melting point; post-cross-linking the polyurethane of the top layer at an elevated temperature as compared with room temperature, preferably at about 130 °C; t h -1I1Iapplying the top layer, withouit previotts r-oughening- of the bottom layer; pre-treating the substrate with a primer before applying the composite material; using a cold-cross-linking polyurethane adhesive as binding agent for the bonding layer.

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se aS 0 I I IIIIIL'ICO~"I- 12 In the following the invention will be explained by way of examples and comparative examples with reference to the accompanying drawings.

Fig. 1 shows a schematic perspective representation of a composite material according to the present invention, and Fig. 2 shows a cross-section of a composite structure according to the present invention comprising an additional multi-layer structure provided on the top layer.

*e The compecrite material shown in Fig. 1 consists of the bottom layer 2 m&de of chloroprene rubber which is still reactive after the complete formation of the composite

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layers and cold-vulcanizable, the bonding layer 3 on the basis of a polyurethane elastomer and the top layer 1 made of a polyurethane elastomer fixedly bonded to the bottom layer 2 by means of the bonding layer 3. For most practical applications, the bottom layer 2 consists of one single chloroprene rubber layer which is cold-vulcanizable and Smay be fixedly bonded onto a correspondingly pre-treated substrate surface, particularly a metal surface, by means of an adhesive as defined above. In the embodiment shown in Fig. 1 the bottom layer 2 consists of three layers 4, 5, 6 provided upon another, where the lower layer 4 provided for being applied onto a substrate, and the upper layer 6 being in contact with the bonding layer 3 or the top layer 1, respectively, consist of prevulcanized, coldvulcanizable chloroprene rubber which, accordingly, still 13 comprises reactive cross-linking sites, and the intermediate layer 5 consists of a partially or preferably completely vulcanized chloroprene rubber.

i This composite material may be fixedly bonded to a substrate 7 according to the method as described above by cold-vulcanization or cold-cross-linking, respectively, by means of a solvent-free reactive adhesive on the basis of Sa polyurethane elastomer or a chloroprene rubber elasto- ;mer.

Such a composite structure is shown in Fig. 2. In accordance with the above, it consists of the composite material shown in Fig. 1, i.e. of the top layer 1 made of che elastomeric polyurethane, the bonding layer 3 and the bottom layer 2 being in contact with the substrate and stronly adhering thereto, wherein the bottom layer 2 again has the same construction a's described above comprising a lower layer 4, an intermediate layer 5 and an upper layer 6.

On the top layer 1, an additional layer 8 is provided consisting of three layer 9, 10, 11 wherein the two outer layers 9, 11 again consist of a prevulcanized and coldi vulcanizable chloroprene rubber, and the intermediate layer 10 consists of a completely vulcanized chloroprene rubber. The outer layer 9 is bonded to the top layer 1 by means of a reactive adhesive as defined above.

On the basis of this method, multi-layer composite materials may be obtained having the advantage of a higher elasticity as compared with composite materials consisting of three layers with a top layer 1 of a corresponding thickness. Further, composite materials of very large thickness may be manufactured in such a way having still I I i i 14 improved structural stability and wherein even under extr.:me thermal and mechanical stress, particularly shear stress, no delamination occurs at the respective interfaces.

The composite material shown in Fig. 1 and the composite I structure shown in Fig. 2 may be manufactured in accor- Sdan, with the above-described method, namely by applying the solvent-free reactive adhesive on the basis of a polyurethane elastomer onto a flat material made of a prevulcanized and cold-vulcanizable chloroprene rubber as bottom layer, providing a layer of a castable polyurethane elastomer on the bottom layer provided with the respective Sbinding agent, and curing or post-curing the polyurethane I, elastomer or the polyurethane elastomer prepolymer, rei* spectively, whereby a top layer is obtained. Subsequently, the obtained composite material may be applied onto a substrate 7.

The invention represents a combination of the coating of substrates with cold-vulcanizable elastomers known as such with a polyurethane top layer which, in turn, shows an extremely good adhesion to the bottom layer because of its formation from a liquid polyurethane elastomer system according to the method of the invention, where the composite material may be applied onto pre-treated substrate surfaces, particularly metal surfaces, in a very simple manner and with rapid fixation without previous roughening by means of the adhesive bonding.

Since processing in an autoclave is not necessary, the method and composite materials and composite structures according to the present invention not only lead to a significantly higher economy, but simultaneously allow a

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i I 15 quicker coating of substrate surfaces as compared with the prior art.

Comparative Example 1 A

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A4 Ot *r A A *Z A S-I A polyurethane sheet on the basis of a polyester polyol was bonded to a steel surface pre-treated in the usual manner, without roughening the polyurethane sheet. As binding agent a chloroprene adhesive was used. The resulting tear resistance was 4 1 N/mm.

Comparative Example 2 The same procedure as in Comparative Example 1 was used, but with previous mechanical roughening of the polyurethane sheet before the bonding. The mechanical roughening of polyurethane flat materials is still more complicated and expensive because polyutethane sheets tend to smear on roughening.

The resulting tear resistance measured as in Comparative Example 1 was about 3 N/mm.

Example in accordance with the present invention A polyurethane elastomer prepolymer on the same basis as in Comparative Examples 1 and 2 was poured in hot state with a temperature above its melting point onto a reactive adhesive layer on the basis of a reactive polyurethane rubber provided on a bottom layer made of a prevulcanized and cold-vulcanizable chloroprene rubber, whereupon the obtained composite material was bonded to steel after stoving in the same manner as in Comparative Examples 1 and 2.

16 The resulting tear resistance was about 20 N/mm.

i N' 9. **ftf 4 i ii i Tearing tests have shown that composite materials according to the present invention show no rupture at the metal chloroprene rubber interface or at the chloroprene rubber polyurethane elastomer interface, but exhibit structural rupture within the polyurethane elastomer layer. This shows the excellent adhesion at the respective interfaces, the improvement of the tear resistanc' by a factor of about 20 or about 7, respectively, as compared with that of the Comparative Examples 1 and 2, being unexpectedly high.

In accordance with the present invention a prevulcanized and still cold-vulcanizable chloroprene rubber is generally used as bottom layer 2, i.e. a chloroprene rubber still having reactive cross-linking centres. Due to the lamination with the top layer by means of the bonding layer which is usually carried out at an elevated temperature as compared with room temperature, a further vulcanization of the bottom layer is induced. Nevertheless, the bottom layer 2 made of chloroprene rubber still has sufficient cold-vulcanizability even in the final composite material according to the present invention to be reactively bonded by means of a suitable adhesive or binding agent, respectively, to substrate surfaces.

The reference numerals in the following claims do not in any way limit the scope of the respective claims.

Claims

17- TEiS CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. A composite material in the form of flat material for coating substrates comprising a bottom layer made of a chloroprene rubber, the underside of which is provided for applying onto a substrate, and a top layer comprising a polyurethane and connected to the upper side of the bottom layer by means of a bonding layer, characterized in that the bottom layer comprises prevulcanized, cold- vulcanizable chloroprene rubber optionally comprising a mineral filler, and the top layer comprises an elastomeric polyurethane optionally comprising a plasticizer, which is made by applying a castable polyurethane system onto the bottom layer coated with a solvent-free reactive binding agent. 20 2. A composite material in the form of flat material for coating substrates comprising a bottom layer made of a chloroprene rubber, the underside of which is provided for applying onto a substrate, and a top layer comprising a polyurethane and connected to the upper side of the 25 bottom layer by means of a bonding layer, obtainable by applying a solvent-free reactive binding agent onto a flat material made of a prevulcanized, cold- vulcanizable chloroprene rubber optionally 30 comprising a mineral filler, as bottom layer, applying a layer of a castable polyurethane elastomer optionally comprising a plasticizer, onto the bottom layer provided with the binding agent, and curing the polyurethane elastomer, thereby obtaining a top layer. i i I L i j i I i i i ""1 ?d I IN i 920909,dbsp.QO19,74215.spe,17 -18- 3. A composite material according to claim 1 or 2, characterized in that the composite material is in the form of sheet material. 4. A composite material according to any one of the preceding claims, characterized in that the substrates to be coated are substrates subject to wear and/or corrosion. 5. A composite material according to claim 1, characterized in that the top layer comprises an elastomeric polyurethane on the basis of a polyester polyol. 6. A composite material according to any one 0oi tnu= i preceding claims, characterized in that the bottom layer is coated with a solvent-free reactive binding agent on the basis of a polyurethane elastomer. 20 7. A composite material according to any one of claims 2 to 4, characterized in that the composite material is applied onto the substrate by bonding with a reactive chloroprene binding agent. 25 8. A composite material according to any one of the preceding claims, characterized in that the bottom layer has a thickness within the range of from about 0.7 to mm and/or the top layer has a thickness within the range of from about 2 to 30 mm. 9. A composite material according to claim 8, characterized in that the bottom layer has a thickness of about 3 mm. 10. A composite material according to claim 8 or 9, characterized in that the top layer has a thickness of V 1 about 15 mm. 920909,dbspec.019,74215..pe,18 -19- 11. A composite material according to any one of the preceding claims, characterized in that the bottom layer comprises three layers provided upon another, wherein the lower layer provided for applying onto the substrate and fixedly adhesive to the substrate, respectively, and the upper layer comprise prevulcanized, cold-vulcanizable chloroprene rubber, and the intermediate layer comprises vulcanized chloroprene rubber. 12. A composite material according to any one of the preceding claims, characterized in that an additional layer made of chloroprene rubber is provided on the top layer, comprising one or more layers and being bonded to the top layer by means of a reactive binding agent on the basis of a polyurethane elastomer. 13. A composite material according to claim 12, characterized in that the chloroprene rubber is prevulcanized, cold-vulcanizable chloroprene rubber. 14. A composite material according to claim 12 or 13, S. characterized in that the additional layer consists of S. three layers with the two outer layers comprising prevulcanized, cold-vulcanizable chloroprene rubber and 25 the intermediate layer consisting of a vulcanized chloroprene rubber, and one of the outer layers being bonded to the top layer by means of a reactive binding agent on the basis of a polyurethane elastomer. 15. A composite material according to any one of claims 12 to 14, charac uerized in that a composite material according to any one of claims 1, 2 and 8 to 14 is provided on the additional layer. 16. A method for producing a composite material according to any one of the preceding claims, comprising the steps of applying a layer of a binding agent onto a S" flat material of a chloroprene rubber, applying a layer 920909,dbspc,019,7421,spe, 19 I of a castable polyurethane elastomer onto the flat material of the chloroprene rubber provided with the binding agent, and curing the polyurethane system, characterized in that a prevulcanized, cold-vulcanizable chloroprene rubber optionally comprising a mineral filler, and as binding agent a solvent-free reactive binding agent, particularly on the basis of a polyurethane elastomer, are used. 17. A method according to claim 16, characterized in that one or more of the following measures are applied in any combination: using a castable polyurethane elastomer on the basis of a polyester polyol for the top layer; using a castable polyurethane elastomer for the top layer comprising a plasticizer; preparing or using a flat material made of a chloroprene rubber as bottom layer in a thickness of about 0.7 to 5.0 mm; producing the top layer of the polyurethane in a thickness of about 2 to 30 mm; applying an additional layer comprising one or more layers made of chloroprene rubber, onto the top layer; applying an additional layer made of three layers, the two outer layers thereof comprising a prevulcanized, cold-vulcanizable chloroprene rubber, and the intermediate layer comprisir 3 a vulcanized chloroprene rubber, by bonding one of the outer layers by means of a reactive binding agent on the basis of a polyurethane elastomer onto the top layer; applying a composite material according to any one of claims 1, 2 and 8 to 14 onto the additional layer; V I I S 920909,dbspec.019,74215.spe,2 -21- applying the castable polyurethane elastomer of the top layer by casting, spin-coating or centrifugation; applying the castable polyurethane elastomer of the top layer at a temperature above its melting point; post-curing the polyurethane of the top layer at an elevated temperature as compared with room temperature; S applying the top layer onto the bottom layer without previous roughing of the bottom layer; and using a cold-cross-linking polyurethane binding agent for the bonding layer.

18. A method according to claim 17, characterized in that the thickness of the bottom layer is about 3 mm.

19. A method according to claim 17 or 18, characterized in that the thickness of the polyurethane is about 15 mm. 20 20. A method according to any one of claims 17 to 19, characterized in that the chloroprene rubber is prevulcanized, cold-vulcanizable chloroprene rubber.

21. A method according to any one of claims 17 to 25 characterized in that the prefabricated compra' material is applied in the form of sheets. e*

22. A method according to any one of claims 17 to 21, characterized in that the metal is steel.

23. A method according to any one of claims 17 to 22, characterized in that the elevated temperature is about 130°C.

24. A composite structure 'on the basis of a substrate as a base, a bottom layer provided thereon and strongly adhesive thereto, made of a chloroprene rubber, and a top layer made of a polyurethane, strongly adhesive to the 920909,dbspc.0 19,74215.spe,21 I i i i ii i.l I i r 1 i -22- bottom layer by means of a bonding layer, characterized in that the bottom layer comprises a prevulcanized, cold- vulcanizable chloroprene rubber optionally 5 comprising a mineral filler, and the top layer comprises an elastomeric polyurethane optionally comprising a plasticizer and made by applying a castable polyurethane system onto the bottom layer coated with a solvent-free reactive binding agent. A composite structure on the basis of a substrate as a base, a bottom layer provided thereon and strongly adhesive thereto, made of a chloroprene rubber, and a top layer made of a polyurethane, strongly adhesive to the bottom layer by means of a bonding layer, obtainable by applying a solvent-free reactive binding agent, onto a flat material made of a prevulcanized, cold- vulcanizable chloroprene rubber optionally comprising a mineral filler, as bottom layer, iPolying a layer of a castable polyurethane elastomer optionally comprising a plasticizer, onto 25 the bottom layer provided with the binding agent, curing the polyurethane elastomer, thereby obtaining a top layer, and applying the obtained composite material onto a substrate.

26. A composite structure according to claim 24 or characterized in that the solvent-free reactive binding agent is on the basis of a polyurethane elastomer.

27. A composite structure according to any one of claims 24 to 26, characterized in that the elastomeric polyurethane is on the basis of a polyester polyol. r 920909,dbspec.019,7421S.spe,22 -23-

28. A composite structure according to claim 25 or 26, characterized in that the composite material is applied on the substrate by bonding with a reactive chloroprene binding agent. S29. A composite structure according to any one of the claims 24 to 28, characterized in that the bottom layer has a thicknens within the range of from about 0.7 to mm and/or the top layer has a thickness within the range i 10 of from about 2 to 30 mm.

30. A composite material according to claim 29, characterized in that the bottom layer has a thickness of I about 3 mm. i 31, A composite material according to claim 29 or characterized in that the top layer has a. thickness of about 15 mm. i 20 32. A composite structure according to any one of claims ji 24 to 31, characterized in that the b .t.om layer eomprises three layerz provided upon another, wherein the I lower layer provided for applying onto the substrate and fixedly adhesive to the substrate, respectively, and the 25 upper layer comprise prevulcanized, cold-vulcanizable chloroprene rubber, and the intermediate layer comprises V vulcanized chloroprene rubber. I 33. A composite structure according to any one of the j 30 claims 24 to 32, characterized in that an additional layer made of chloroprene rubber is provided on the top layer, comprising one or more layers and being bonded to V, top layer by means of a reactive binding agent on the basis of a polyurethane elastomer.

34. A composite structure according to claim 33, characterized in that the chloroprene rubber is Sprevulcanize cold-vulcanizable chloroprene rubber. S: 920909,dbspec.19,74215.spe,23 '4- -24- A composite structure according to claim 33 or 34, characterized in that the additional layer consists cf three layers with the two outer layers comprisijig prevulcanized, cold-vulcanizable chloroprene rubber and 5 the intermediate layer consisting of a vulcanized chloroprene rubber, and one of the outer layers being bonded to the top layer by means of a reactive binding agent on the basis of a polyurethane elastomer.

36. A composite structure according to any one of claims 33 to 35, characterized in that: a composite material according to any one of claims 1, 2 and 8 to 14 is provided on the additional layer.

37. A composite structure according to any one of claims 24 to 30, characterized in that the substrate consists of a metal, a plastic material, wood, cement or concrete.

38. A composite structure according to claim 37, 20 characterized in that the metal is steel.

39. A composite structure according to any one of claims 24 to 31, characterized in that the substrate is a container on the inner surface of which the composite 25 material is provided.

40. A method for producing a composite structure according to any one of claims 24 to 39, comprising the steps of applying a layer of a binding agent onto a flat 30 material of a chloroprene rubber, applying a layer of a castable polyurethane elastomer onto the flat material of the chloroprene rubber provided with the binding agent, curing the polyurethane system to produce a composite material and applying the composite material onto a substrate, characterized in that a prevulcanized, cold-vulcanizable chloroprene rubber optionally comprising a mineral filler, o i 3 i j r j i i i I W Ljtb rr 920909,dbspe;4 fkl9,7421.spe,24 i and as binding agent a solvent-free reactive binding agent, particularly on the basis of a polyurethane elastomer, are used.

41. A method according to claim 40, characterized in that one or more of the following measures are applied in any combination: using a castable polyurethane elastomer on the basis of a polyester polyol for the top layer; using a castable polyurethane elastomer for the top layer comprising a plasticizer; S preparing or using a flat material made of a chloroprene rubber as bottom layer in a thickness of about 0.7 to 5.0 mm; S prodlciing the top layer of the polyurethane in a thickness of about 2 to 30 mm; S applying an additional layer comprising one or more layers made of chloroprene rubber, onto the top layer; applying an additional layer made of three layers, the two outer layers thereof comprising a ii !I 4f.? prevulcanized, cold-vulcanizable chloroprene rubber, and the intermediate layer comprising a vulcanized chloroprenc rubber, by bonding one of the outer layers by means of a reactive binding agent on the basis of a polyurethane elastomer onto the top layer; applying a composite material according to any one of claims 1, 2 and 8 to 14 onto the additional layer; applying a prefabricated composite material according to any one of claims 1, 2 and 8 to 14, onto a substrate of a metal, plastics, wood, cement or concrete; applying the castable polyurethane elastomer of the top layer by casting, spin-coating or 920909,dbspec.019,74215.spe,25 IC~C3"1~I~ ii -26- centrifugation; applying the castable polyurethane elastomer of the top layer at a temperature above its melting point; post-curing the polyurethane of the top layer at an elevated temperature as compared with room temperature; applying the top layer onto the bottom layer without previous roughing of the bottom layer; pre-treating the substrate before applying the composite material with a primer; and using a cold-cross-linking polyurethane binding agent for the bonding layer.

42. that A method according to claim 41, characterized in the thickness of the bottom layer is about 3 mm. i :2 i II i: i i r i i 2 i -r

43. A method according to claim 41 or 42, characterized in that the thickness of the polyurethane is about 15 mm.

44. A method according to any one of claims 41 to 43, characterized in that the chloroprene rubber is prevulcanized, cold-vulcanizable chloroprene rubber.

45. A method according to any one of claims 41 to 44, 25 characterized in that the prefabricated composite material is applied in the form of sheets.

46. A method according to any one of claims 41 to characterized in that the metal is steel.

47. A method according to any one of claims 41 to 46, characterized in that the substrate is an inner surface of containers.

48. A method according to any one of claims 41 to 47, characterized in that the prefabricated composite material is applied onto a substrate by bonding. 920909,dbspec.019,74215.spe,26 r_ i i -~-CiUli -27-

49. A method according to any one of claims 41 to 48, characterized in that the prefabricated composite material is applied onto a substrate by means of a cold- vulcanizable chloroprene rubber binding agent. A method according to any one of claims 41 to 49, characterized in that the elevated temperature is about 1300C.

51. Composite materials or composite structures or methods for producing the composite materials or composite structures substantially as hereinbefore described with reference to the drawings and/or Examples (excluding the Comparative Examples) i i' Vt i, I DATED this 9th day of September, 1992. 25 STAHLGRUBER OTTO GRUBER GMBH CO. By Its Patent Attorneys DAVIES COLLISON CAVE i 1 VS -r' 920909,dbspec.019,74215.spe,27