NO760486L - - Google Patents

Description

"Procedure for the manufacture of

foamed coating materials."

This invention relates to the production of surface coating materials which, for example, comprise floor coating materials, wall coating materials and coating materials for shelves, worktops and the like.

Polyvinyl chloride surface coating materials are well known, and when the term "polyvinyl chloride" is used herein, it includes both vinyl chloride homopolymers and copolymers. Such surface coating materials can be produced in a number of ways. For example, sheets of polyvinyl chloride material can be formed using calendering equipment and then laminated together to provide surface coating materials. In another method, polyvinyl chloride plastisols are applied to a substrate after which the plastisol is gelled and, if desired, additional layers of polyvinyl chloride are applied to provide surface coating materials of suitable thickness. But such surface coating materials are often subject to edge curling and dimensional instability. To prevent such defects, a layer of polyvinyl chloride material can be applied to both sides of the substrate, thereby achieving a balance between material on both sides of the substrate, for example as described in our British patent document No. 1,029,085.

For some purposes, particularly where floor covering materials are concerned, it is desirable to incorporate foamed polyvinyl chloride material into the surface coating to provide a product of increased thickness having elasticity and good wearing surface properties. It is thus known to produce floor covering materials which comprise a foamed layer, by introducing heat-activatable blowing agents into layers of polyvinyl chloride material produced by calendering or by gelling polyvinyl chloride plastiosels, and then causing splitting of the blowing agent and consequently foaming. However, it has been found that the incorporation of a foamed polyvinyl chloride layer in surface coating materials of the type described in our above-mentioned British patent can result in surface coating materials of excessive thickness due to the need, discussed above, to achieve a balance of material on both sides of the substrate if can curling and dimensional instability are to be avoided.

The present invention is based on the discovery that foamed surface coating materials with desired properties can be obtained if, instead of applying a foamable resin mixture as a separate layer to a non-woven substrate that can be impregnated with a non-foamed resin mixture, the substrate is impregnated with a foamable resin mixture. Thus, according to a feature of the present invention, a method for the production of foamed surface coating materials is provided which comprises the steps of impregnating at least selected zones of a non-woven substrate with at least one foamable resin mixture through at least a substantial part of the thickness of the substrate and then causing foaming of the foamable resin mixture(s).

According to a further feature of the invention, a foamed surface coating material is provided which comprises a non-woven substrate, the substrate being impregnated in at least some zones thereof with foamed resin material.

The non-woven substrate used preferably consists of non-woven glass fibres, and such a material is usually available in both "wet laid" and "dry laid" form. It is convenient to use a non-woven substrate which has as flat and even a surface as possible, and consequently "wet laid" non-woven glass fabric is advantageously used. When the non-woven substrate is bonded by means of a thermosetting binder, as is usually the case with substrates of non-woven glass material, it is necessary that the thermosetting binder is stable at the temperatures that are subsequently encountered, e.g. . by heat treatment to effect expansion of the foamable resin mixture. It is important that the substrate has a sufficiently open casting form so that it can be impregnated with a foamable resin mixture. With regard to thickness, it is convenient for the substrate to be sufficiently thick so that it can provide sufficient strength to be easily handled, and with non-woven glass fabric it is preferred to use fabric weighing at least 30 g/m , and fabric weighing from 30 to 100 g/m 2 , advantageously from 35 to 70 g/m 2 , and more particularly from 50 to 60 g/m 2 , is particularly preferred.

If desired, the substrate can be subjected to full coverage impregnation with a simple foamable resin mixture. However, according to a preferred embodiment of the method according to the present invention, only selected parts of the substrate are impregnated with a foamable resin mixture while other areas are impregnated with a non-foamable resin mixture and/or one or more additional foamable resin mixtures which have different foaming properties than the the former foamable resin mixture. Two or more resin mixtures can thus be applied, as at least one such mixture is foamable. By selective application of resin mixtures, surface coating materials can be obtained which have textured effects.

The foamable and non-foamable resin mixtures

are preferably polyvinyl chloride plastisols.

The amount of foamable resin mixture applied is preferably sufficient to impregnate at least 50%, preferably at least 75%, and more particularly 95-100%, of the thickness of the non-woven substrate. The part of the non-woven substrate that is not impregnated is thus, in a way, unused material when it comes to the present invention. With non-woven glass fabric weighing, for example, from 50 to 60 g/m 2 , it is necessary to apply from 300 to 700 g/m 2 of foamable resin mixture to achieve impregnation of at least 95% of the thickness of the substrate. In order to apply such quantities of foamable mixture to selected areas of the substrate, the application is conveniently carried out by the technique consisting of rotary "screen printing". In this impingement method, the foamable resin mixture is forced through a rotating cylindrical metal screen and onto the substrate. The pattern is formed by either covering areas of the sight, e.g. by using a crosslinkable varnish, or alternatively by using a screen which, instead of having meshes everywhere, has meshes that have the shape of the desired pattern, while other areas of the screen do not have mesh holes. When using selective impregnation, it is usually desirable to gel the foamable resin mixture at a temperature insufficient to cause the mixture to foam.

After applying a first foamable mixture to selected areas of the substrate, it is possible, if desired, to apply a substance weighing at least 30 g/m 2 and a substance weighing from 30 to 100 g/m 2 , advantageously from 35 to 70 g/m 2 , and more particularly from 50 to 60 g/m 2 , is particularly preferred.

If desired, the substrate can be subjected to full coverage impregnation with a simple foamable resin mixture. However, according to a preferred embodiment of the method according to the present invention, only selected parts of the substrate are impregnated. with a foamable resin mixture while other areas are impregnated with a non-foamable resin mixture and</>or one or more additional foamable resin mixtures having different foaming properties than the first-mentioned foamable resin mixture. Two or more resin mixtures can thus be applied, with at least one such mixture being foamable. By selective application of resin mixtures, surface coating materials can be obtained which have textured effects.

The foamable and non-foamable resin mixtures

are preferably polyvinyl chloride plastisols.

The amount of foamable resin mixture. which is applied, is preferably sufficient to impregnate at least 50%, preferably at least 75%, and more particularly 95-100%, of the thickness of the non-woven substrate. The part of the non-woven substrate that is not impregnated is thus, in a way, unused material when it comes to the present invention. With non-woven glass fabric weighing, for example, from 50 to 60 g/m^, it is necessary to apply from 300 to 700 g/m 2 of foamable resin mixture to achieve impregnation of at least 95% of the thickness of the substrate. In order to apply such quantities of foamable mixture to selected areas of the substrate, the application is conveniently carried out by the technique consisting of rotary "screen printing". By this imprinting method. the foamable resin mixture is forced through a rotating cylindrical metal screen onto the substrate. The pattern is formed by either covering areas of the sight, e.g. by using a crosslinkable varnish, or alternatively by using a sieve which, instead of having meshes everywhere, has meshes that have the shape of the desired pattern, while other areas of the sieve do not have mesh holes. By. application of selective impregnation, it is usually desirable to gel the foamable resin composition at a temperature insufficient to cause the composition to foam.

After having applied a first foamable composition to selected areas of the substrate, it is dm desired possible to apply one or more further foamable compositions to other areas of one or more further foamable compositions to other areas of the substrate, and this again can conveniently be done with one such technique that uses rotary screen printing followed by heating to effect gelation. It is possible in some ways by using different foamable mixtures which, after heating, will expand to different degrees, to produce final products with textured effects without using non-foamable mixtures.

With this, it is usually preferred, after applying one or more foamable mixtures, to apply a substantially non-foamable resin mixture in order to complement and thus impregnate the areas of the substrate that are not previously impregnated with foamable mixtures and also to level the surface of the impregnated substrate on the side facing up on the finished surface coating material. And again it is advantageous that the amount of non-foamable resin mixture applied is sufficient to impregnate at least 50%, preferably at least 75%, and more particularly 95-100%, of the thickness of the non-woven substrate. It can be applied if desired

sufficient non-foamable resin mixture to not only complement but also to provide a solid surface layer covering the surface of previously applied foamable resin mixture.

When such an all-over surface is gelled against a hot casting roll, a very smooth, flat surface is produced which is very well suited to receiving an imprinted layer, especially a layer that is imprinted by the gravure process.

In one embodiment of the present invention, the complementary non-foamable composition may be applied by conventional coating techniques, e.g. by using a coating knife or an air knife or by rotary "screen printing" equipment with a mesh screen over the whole. The complementary non-foamable mixture is then gelled, preferably by means of a hot casting roll.

By an alternative method of. applying the complementary non-foamable resin composition, which provides an alternative embodiment of the present invention, the impregnation of the non-foamable composition is carried out by pressing the partially impregnated substrate into a layer of the non-foamable composition. When carrying out this method, it is usually preferred to apply the partially impregnated substrate to the layer of non-foamable mixture with the surface on which the foamable mixture(s) have been applied, at the top, so that the non-foamable mixture is absorbed into the substrate on the side of the substrate furthest from the side on which the foamable mixture has been applied. This can conveniently be carried out by pressing the partially impregnated substrate into a layer of non-foamable resin mixture. It is important that the non-foamable mixture substantially completes the impregnation of the substrate in order to exclude as much air as possible from the substrate. The layer of non-foamable mixture into which the partially impregnated substrate is pressed, e.g. by stretching, over a roller, can, if desired, be carried on a preformed plastic sheet, for example a calendered polyvinyl chloride sheet, and then, after subsequent gelation of the preformed sheet, be bonded to the substrate and serve as a backing layer for it. The layer of non-foamable composition may alternatively be supported on a release substrate, in which case excess non-foamable composition adhering to the substrate may provide eri backing.

For. to gel the resin mixtures, the substrate can be passed over a hot casting roll whereby any resin mixture that adheres to the surface is cast into a smooth, flat surface.

The surface of the impregnated non-woven substrate on which the foamable resin mixture is applied should preferably face up in the finished product. It is usually desirable with surface coating materials to provide a pattern on the material and it is also often desirable to apply a wear layer to improve the wear properties of the product. In order to provide a final product with a pleasing appearance, it is usually advantageous to ensure that the surface of the impregnated nonwoven substrate to which a printed pattern and, if desired, a wear layer is applied, is as flat and free of irregularities as possible. In the above-described method according to the invention, this can be achieved by applying a full-covering coating to the surface of both foamable and non-foamable mixtures and subsequent gelation. Any desired printed pattern can then be applied to the surface of the covering coating. But this method involves additional coating and gelation, and this results in additional costs for the production of the product. It is therefore preferred to provide as smooth a surface as possible during the gelation step which follows the application of the non-foamable compositions, and it has been found that if the gelation is carried out by a special method (which method is an important feature of the present invention), surface coating materials with an appealing appearance can be obtained without having to apply a

special covering coating.

The gelling method which is advantageously used according to the present invention thus comprises bringing the impregnated substrate, after filling with the non-foamable mixture, into contact with the surface of a heated roller, preferably using a pinch-roller system, whereby the surface of the impregnated substrate on which the foamable mixture has been applied and which will face upwards in the final product, is leveled and smoothed as the gelation takes place.

The heated surface of the roller is suitable

a smooth metal surface. When the partially impregnated substrate is pressed into a layer of non-foamable mixture to effect filling, it is possible to use a clamping system with a heated roller whereby the impregnation of the non-foamable mixture and the gelation of the non-foamable mixing thus applied is carried out simultaneously.

As mentioned, it is usually desirable to provide a pattern in the finished surface coating material. One method of providing such a pattern is to use pigmented foamable and non-foamable mixtures. If this is done, the surface of the impregnated substrate is leveled during the gelation of the non-foamable mixture, as described above, and a transparent wear layer is added for subsequent heating to expand the foamable mixture, and thus a product can be obtained where a pattern is provided which is in exact accordance with the textured effect achieved due to expansion of the foamed mixture.

Another method of providing a pattern involves embossing. on the areas of the substrate that are impregnated with foamable mixture, or on the gelled, leveled surface of the completely impregnated substrate. Such printing can conveniently be carried out by rotary "screen printing" or gravure printing,

but other printing techniques can also be used if desired, so

like for example. block printing. The applied pattern may be in close agreement with any textured effect provided by subsequent foaming of the foamable resin composition. It is usually preferred to apply an all-over transparent wear layer to the assembly. The wear layer is conveniently provided in both cases with a polyvinyl chloride mixture and is preferably applied as a polyvinyl chloride plastisol, but it may be desired

preformed calendered films are used. The thickness of the wear layer is suitable from 0.1 to 1.0 mm.

After the application of the wear layer, assembly can be carried out

. is heated so that foaming is achieved.

A particular advantage of the method according to this invention is that relatively thin floor coverings or other surface covering materials can be produced, which nevertheless have properties that are usually associated with thicker and more expensive materials. With, for example, floor covering materials comprising a non-woven substrate and a foamed resin layer applied to this substrate, as previously explained it is usually necessary to achieve balancing to have materials on both sides of the substrate if edge curling is to be avoided and the dimension instability. Thus, when a floor covering material includes a substrate, foamed mixture carried on the substrate and a wear layer on said foamed mixture, balancing material of substantial thickness is usually required on the underside of the substrate. When using the present origin, it is only necessary to have a wear layer on the upper surface of the impregnated substrate, and thus any balancing backing layer on the underside of the substrate only needs to be of a relatively small thickness. The combination of the substrate and the foamed layer eliminates one layer from the final product, compared to products that have a separate foamed layer. It has also been found that non-woven substrates, and in particular non-woven glass fabric, maintain sufficient reinforcing and stabilizing properties, despite being impregnated with a foamable composition which is subsequently foamed, to provide surface coating materials with sufficient strength and uncommon dimensional stability when incorporated into relatively thin surface coating materials. It has in fact been found that the foam-impregnated substrate provides a product that feels firm and elastic, and this is believed to be a particularly desirable property of the products according to the invention, while the presence of the non-woven matrix at or near the wear layer supports the wear layer , and this means that the wear layer feels hard. Thus, according to the present invention, for example, floor covering materials can be produced with a total thickness of from 1.2 to 1.5 mm, which includes a foamed layer, which is essentially free of a tendency to edge curling and which has good strength and dimensional stability. In reality, the thickness of such floor covering materials can, if desired, be reduced to less than 1.2 mm,

for example, down to 1 mm or less, and increased to 2.5 mm or more.

When necessary, a balancing backing layer can be provided, as previously described, by using a calendered film carrying a non-foamable composition to complement the partially impregnated substrate, whereby the calendered film after subsequent gelation is debonded to the substrate.

Alternatively, a backing layer can then be applied either by lamination by heating or gluing a pre-formed calendered sheet or by coating with a resin mixture and subsequent gelling using infrared heaters or by contact with a heated roller. Other possibilities include the use of hot melt compounds, thermoplastic compounds of low molecular weight polypropylene, acrylic plastic emulsion compounds and the like.

When a surface coating material according to the invention consists of a foamed layer with an incorporated non-woven substance according to the present invention, a wear layer and a backing layer, it should be understood that the backing layer should preferably at least "balance" the wear layer. Thus, when both the wearing layer and the backing layer are polyvinyl chloride materials, the backing layer should have a greater thickness than the wearing layer. When the polyvinyl chloride wear layer has a thickness of from 0.1 to 1 mm, backing layers of suitable thicknesses in the range from 0.25 to 1.2 mm are usually conveniently used.

The foamable and non-foamable resin mixtures used in the method according to the present invention are preferably polyvinyl chloride plastisols, and they should have such viscosities that the desired impregnation of the substrate is achieved. Such polyvinyl chloride plastisols may for example contain, in addition to polyvinyl chloride resin, plasticizers, stabilizers, fillers, viscosity modifiers, volatile additives and pigments, together with, in the case of foamable mixtures, a blowing agent and blowing agent activators or "kickers".

The polyvinyl chloride included in the plastisol can be a homopolymer or a copolymer. When copolymers are used, these preferably contain a major proportion of units originating from vinyl chloride. Other copolymerized monomers which may be incorporated into the copolymer if desired include, for example, vinyl acetate and vinylidene chloride. When it comes to mixtures for rotary screen printing, the particle size of the polymer used is important because the polymer particles. and the filler particles must easily pass through the rotary screen used in the printing. The particle shape can also be of importance in achieving a plastisol mixture that has the most desired viscosity properties for rotary screen printing. Generally, the particle shape should be chosen with a view to increasing the pseudoplastic character of the plastisol. A polyvinyl chloride polymer that can be advantageously used in the formation of plastisols for rotary "screen printing" is that known under the trade name "Vipla PM".

The plasticizers used in polyvinyl chloride plastisols for rotary "screen printing" are usually phthalate plasticizers, for example nonyl, octyl, butyl, butylbenzyl and diphenyl phthalates. Phosphates (e.g. trixylenyl and tricresyl phosphates), adipates and sebacates can, for example, also be used as plasticizers.

It is usually necessary to incorporate a certain amount of a stabilizer into plastisols, and the stabilizer is a substance capable of inhibiting decomposition of the resin during mixing and subsequent exposure to light. The chosen stabilizer is preferably one which also has the property that it can cause the blowing agent to split over a narrower temperature range, hereinafter referred to as a "stabiliser kicker". Dibasic lead phthalate is a suitable stabilizer kicker, and other substances which are used include certain other lead-containing compounds, certain organotin compounds and certain metal soaps, especially stearates of metals such as zinc, cadmium, barium and aluminium.

The blowing agent that is incorporated into the foamable plastisol is usually an organic substance that releases nitrogen when heated. Substances that are conveniently used as blowing agents are those that decompose over a relatively narrow temperature range. A particularly suitable blowing agent for use in the method according to the invention is azodicarbonamide.

As possible components, fillers can be incorporated into the plastisols. Various inorganic substances can be used as fillers, and the most convenient is calcium carbonate, e.g. in the form of slimy chalk, precipitated lime, ground limestone or ground dolomite.

Viscosity-modifying agents can also be incorporated when it is necessary to influence the viscosity properties of the plastisols, and hexylene glycol is an example of a viscosity-modifying agent that can conveniently be used.

Volatile additives can also be incorporated into the plastisols. Examples of such additives are solvents such as white spirit, kerosene, dodecylbenzene and low-boiling esters.

Preferred plastisols for use according to the present invention contain, for every 100 parts by weight of polymer present, from 30 to. 100 parts by weight softener, up to

.5 parts by weight stabilizer, up to 10 parts by weight blowing agent, up to 30 parts by weight, preferably up to 15 parts by weight filler, up to 10 parts by weight viscosity modifier and up to 20 parts by weight volatile additive.

To better illustrate the present invention,

reference must be made to the accompanying drawings. Figures 1

to 11 show schematic steps in the production of foamed surface coating materials according to two embodiments of the present invention. Figure 12 of the accompanying drawings is a schematic diagram of apparatus for adhering a layer of resin mixture to a partially impregnated nonwoven fabric.

Figure 1 shows a non-woven glass fabric 1. In Figure 2, selected parts of fabric 1 in Figure 1 have been impregnated with a foamable resin mixture 2. In Figure 3, parts of the non-woven fabric 1 that have not been impregnated with the foamable resin mixture 2, has been filled with a non-foamable resin mixture 3 which also provides a full coverage coating. In figure 4, a decorative pattern 4a, 4b has been printed on the surface of the solid coating in close correspondence with the areas of foamable mixture. Pattern 4a has been printed over the foamable mixture while pattern 4b has been printed over the non-foamable area. In Figure 5, a wear layer 5 has been applied. Figure 6 shows the assembly after foaming. Finally, figure 7 shows that a backing layer 6 has been applied.

In Figure 8, a plastisol 7 has been applied to a calendered backside 8 and the calendered backside 8, and substrate 2 has been combined whereby the plastisol 7 complements the substrate 2 and provides a full coverage coating 9 on the side of the substrate 2 furthest from the backside 8. In Figure 9, decorative patterns 4a and 4b have been printed on the surface of the all-covering coating, as in Figure 4. In Figure 10, a wear layer 5 has been applied. Figure 11 shows the assembly after foaming.

Reference is now made to figure 12 where a calendered PVC layer 8 coated with PVC plastisol 7 is brought together with a non-woven glass fabric 2 while being stretched over a roller 10 and around a hot casting roller 11. The combined layer is then carried away over a roller 12.

The following example illustrates the production of a textured foam floor material using a substrate in accordance with the present invention.

Example

A foamable resin mixture with the following composition is produced:

The foam master mix used in the formation of the above mix was prepared in advance from the following:

This foamable resin composition which is in the form of a paste, suitable for printing through a rotary screen printer, is applied to a non-woven glass fiber fabric in selected areas at a coating density of 300 g/m . The coated substrate is then dried by infrared heating at 140°C followed by cooling in contact with a water-cooled roll.

The non-woven glass fiber fabric used as substrate comprises glass fibers with an average diameter of 16 microns bonded with a cross-linked urea formaldehyde resin. The total substance weight of the material is 60 g/m 2.

A non-foam bar is then produced

resin mixture with the following composition:

The non-foamable resin mixture, which is in the form of a sprayable paste, is applied as a solid coating with a spreader knife to the printed non-woven glass fabric. This coating complements the areas in the glass fabric between the areas of foamable printing, and provides a thin continuous layer over the entire surface. The coating density in the non-printed areas is approximately 300 g/m 2 and the coating thickness over the printed foam is approximately 0.1 mm. The coated/filled tissue is then fed into a clamp formed between a water cooled rubber coated roll and a PTFE coated steel roll heated to 180°C. The coated web is kept in contact with the heated roller on at least 50% of its circumference.

The substrate is then imprinted on its coated surface with an appropriate pattern in close correspondence with the areas of imprinted foamable compound using conventional rotogravure printers and PVC inks.

A third mixture is then produced which serves to provide a transparent wear layer, with the following composition:

The third mixture, which is in the form of a sprayable paste, is applied with a spreader knife as an all-over coating having a thickness over the surface of the gravure-printed layer of 0.2 mm.

The assembly is then heated in a hot air oven for approximately 2 minutes at 180°C to gel the plastisols and expand the foamable mixture. The assembly is then cooled.

A further non-foamable resin mixture with the following composition is then produced:

This mixture is mixed in an internal mixer and calendered to a thin continuous film with a total thickness of 0.5 mm.

An adhesive based on a solution of acrylonitrile rubber is applied to the side of the impregnated non-woven fabric furthest from the wear layer and to one side of the calendered layer using reverse roller coaters. The adhesive is dried by passing both layers through a flame-proof hot air oven before the layers are brought together, and adhesive is then brought into contact with adhesive through a pressure clamp for debonding. The assembly is then cooled and rolled to provide the final product.

Claims (52)

1. Foamed surface coating material, characterized in that it comprises a non-woven substrate, the substrate being impregnated at least in some zones thereof with foamed resin material. 2. Surface coating material as specified in claim 1, characterized in that substantially all of the non-woven substrate is impregnated with the foamed resin material. 3. Coating material as stated in claim 1, characterized in that it includes zones that are not impregnated with the foamed resin material, whereby substantially all of the said zones are impregnated with non-foamed resin material. 4.B laying material as stated in any one of claims 1 to 3, characterized in that the substrate is a non-woven glass material. 5.B laying material as specified in any one of claims 1 to 4, characterized in that the substrate is supported on a backing layer. 6. Coating material as specified in any of claims l to 5, characterized in that the surface furthest from the backing layer, when present, is provided with an all-covering layer of non-foamed resin material. 7. Coating material as set forth in any one of claims 1 to 6, characterized in that it also includes a decorative pattern. 8.B paving material as stated in claim 7, characterized in that the decorative pattern is at least partially in exact agreement with the zones of foamed resin material. 9. Coating material as stated in any of claims 1 to 8, characterized in that pigments are incorporated into any of the aforementioned resin materials. 10.B paving material as stated in any one of claims 1 to 9, characterized in that it further includes a fully covering wear layer. 11. Coating material as stated in claim 10, characterized in that the wear layer is transparent. 12.. Coating material as specified in claim 10 or 11, characterized in that the wear layer has a thickness of from 0.1 to 1.0 mm. 13. Coating material as stated in claim 12, characterized in that it has a backing layer with a thickness of 0.25 to 1.2 mm. 14. Coating material as stated in any of claims 1 to 13, characterized in that it has a total thickness of from 1 to 2.5 mm. 15.B paving material as stated in claim 14, characterized in that it has a total thickness of from 1.2 to 1.5 mm. 16.B covering material as specified in any of claims 1 to 15, characterized in that it has the form of a floor covering material. 17. Method for producing foamed surfaces . , -, ■ • , as stated in claim 1 , , tea coating materials/, characterized by the steps comprising impregnating at least selected zones of a non-woven substrate with at least one foamable resin mixture through at least a substantial part of the thickness of the substrate and then causing foaming of the foamable resin mixture(s). 18. Method as stated in claim 17, characterized in that a substrate comprising a non-woven glass material is used. 19. Method as stated in claim 18, characterized in that a substrate comprising a "wet-laid" non-woven glass fabric is used. 20. Method as stated in claim 18 or 19, characterized in that a glass substance is used which has a weight - per area unit of at least 30 g/m <2> . 21. Method as stated in claim 20, characterized in that a glass substance is used which has a weight per area unit of from 30 to 100 g/m . 22. Method as stated in claim 21, characterized in that a glass substance is used which has a weight per area unit from 35 to 70 g/m . 23.. Procedure as stated in claim 22, character-. certified by using a glass substance that has a weight per area unit of from 50 to 60 g/m . 24. Method as stated in any one of claims 18 to 23, characterized in that the substrate is debonded. using a suitable thermosetting binder. 25. Method as stated in any of the preceding claims, characterized in that the substrate is subjected to impregnation essentially over the whole with a single foamable resin mixture. 26. Method as set forth in any one of claims 17 to 24, characterized in that selected zones of the substrate are impregnated with a first foamable resin mixture leaving other zones that are not impregnated by said first foamable mixture. 27. Method as stated in claim 26, characterized in that at least some of the zones in the substrate which are not impregnated with the first foamable resin mixture are selectively impregnated with one or more further foamable resin mixtures which have foaming properties different from the first-mentioned foamable resin mixture. 28. Method as stated in claim 26, characterized in that essentially all zones in the substrate which are not impregnated with a foamable resin mixture are impregnated with a non-foamable resin mixture. 29. Method as set forth in claim 28, characterized in that impregnation with the non-foamable mixture is carried out by applying a layer of the non-foamable mixture to the surface of the substrate which lies farthest from it. foamable mixture has been applied. 30. method as stated in claim 28 or 29, characterized in that the layer of non-foamable mixture is supported on a pre-formed plastic sheet which is capable of binding to the substrate by subsequent gelation and then forming a backing layer for this. 31. Method as stated in claim 28 or 29, characterized in that a separate backing layer is applied to one surface of the impregnated non-woven substrate. 32. Method as stated in claim 31, characterized in that a pre-formed, calendered sheet is laminated to the substrate by means of heat or adhesive, the sheet serving as a backing layer. 33. Method as stated in claim 31, characterized in that a backing layer is applied by coating a surface of the substrate with a resin mixture and then gelling the mixture. 34. Method as stated in any of the preceding claims, characterized in that the resinous mixture(s) is applied to impregnate at least 50% of the thickness of the non-woven substrate. 35. Method as stated in claim 34, characterized in that the resinous mixture(s) is applied to impregnate from 95 to 100% of the thickness of the non-woven substrate. 36. Method as stated in claim 35, characterized in that the foamable resin mixture is applied in an amount of from 300 to 700 g/m on a non-woven glass fabric substrate. 37. Method as stated in any of the preceding claims, characterized in that the resin mixture. applied to selected areas by rotating "screen printing". 38. Method as stated in any of the preceding claims, characterized in that a full coverage coating is applied to one surface of the impregnated non-woven substrate. 39. Method as stated in claim 38, characterized in that the substrate is impregnated with a non-foamable resin mixture, the non-foamable resin mixture being applied to additionally form the full coverage coating. 40. Method as stated in any of the preceding claims, characterized in that it impregnated substrate is brought into contact with a heated roller, whereby gelation of the resinous mixture(s) is effected. 41 Method as stated in any of the preceding claims, characterized in that it includes the step of applying a decorative pattern to the impregnated non-woven substrate. 42. Method as stated in claim 41, characterized in that the decorative pattern is printed on the surface of a leveling coating which is applied to the non-woven substrate. 43. Method as stated in claim 41 or 42, characterized in that the decorative pattern is applied by rotary "screen printing". 44. Method as stated in any of the preceding claims, characterized in that one or more resin mixtures containing a pigment are used. 45. Method as stated in any of the preceding claims, characterized by the further step of applying a fully covering wear layer to the entire assembly. 46. Method as stated in claim 45, characterized in that a transparent wear layer is applied. 47. Method as stated in claim 45 or 46, characterized in that the wear layer is applied as a polyvinyl chloride plastisol. 48. Method as stated in any one of claims 45 to 47, characterized in that the wear layer is applied to a thickness of from 0.1 to 1.0 mm. 49. Method as stated in any of the preceding claims, characterized in that one or more foamable and/or non-foamable resin mixtures comprising polyvinyl chloride plastisol(s) are used. 50. Method as stated in claim 49, characterized in that a foamable resin mixture comprising a polyvinyl chloride plastisol containing a blowing agent is used. 51. Method as stated in claim 50, characterized in that a blowing agent comprising azodicarbonamide is used. 52. Method as stated in any of the preceding claims, characterized in that a foamable resin mixture is used which contains per 100 parts by weight polymer from 30 to 100 parts by weight plasticizer, up to 5 parts by weight stabilizer, up to 10 parts by weight blowing agent, up to 30 parts by weight filler, up to 10 parts by weight viscosity modifier and up to 20 parts by weight volatile additive.