NL8703120A - RESILVED SURFACE COATING WITH A WEAR LAYER AND METHOD FOR PROVIDING SUCH SURFACE COATING. - Google Patents

Description

t

873090 / BA / HH

Resilient surface coating with a wear layer and method of providing such a surface coating.

The present invention relates to a resilient surface coating, comprising a resilient support and an adhered cross-linked wear layer.

Resilient surface coatings, in particular resilient floor coverings, are known.

The floor coverings commonly used today are mainly of a vinyl construction and, although they can be made with varying degrees of flexibility, they are resilient compared to conventional natural materials such as a ceramic tile. A variety of such products are commercially available and these products have shown to have good abrasion resistance; yet these coverings are not without certain flaws. For example, vinyl floor coverings have proven to be durable and stain resistant; however, they tend to lose their glossy appearance through wear. A high-gloss appearance for a floor covering is often desired. Accordingly, the manufacturers of such materials have long sought to find improved floor coverings that exhibit good gloss retention.

One method of providing improved gloss retention is the use of polyurethane or other wear layers on vinyl floor covering structures.

Such materials are durable and relatively scratch resistant, and they tend to retain their high gloss appearance over a longer period of time than is the case with vinyl surface floor structures.

Nevertheless, these wearing layers and in particular polyurethane wearing layers also have certain drawbacks. For example, they are more sensitive to stains. Thus, when exposed to common skin care items that tend to stain (such as ball-point pen, lipstick, mustard, shoe polish, etc.), polyurethane coatings tend to be more easily stained than vinyl coatings. is the case. In recent years, considerable efforts have been made by the industry to develop new and different types of coatings comprising coatings based on aminoplast resins. Such materials include urea resins and melamine-formaldehyde resins such as melamines (tri-aminotriazines) which are N-alkylated with formaldehyde to provide melamine-backed or partially methylol-backed melamine. The methylol groups are then etherified or partially etherified to provide a cross-linkable material. Such coatings are generally quite rigid and have found wide application in coatings for cars, equipment and other fairly rigid surface types.

They have also been used in coatings for certain flexible substrates including paper, cardboard, metal foil, cellophane and the like. However, such materials have never been successfully used for floor covering structures and in particular on vinyl floor covering structures or on vinyl floor covering structures comprising polyurethane wearing layers.

Accordingly, an object of the present invention is to provide resilient surface coatings with protective layers with a thickness of 5 µm or more that can deform along with the surface coatings but still exhibit improved scratch and stain resistance.

Another object of the present invention is to provide floor covering structures comprising composite wear surfaces wherein the wear layer material has an improved scratch and stain resistant character.

These and other advantages of the present invention will become apparent from the detailed description of the preferred embodiments which follows.

These aforementioned objects are achieved according to the invention by a resilient surface coating comprising a resilient support and an adhered cross-linked wear layer which is characterized in that the top surface of said wear layer comprises a protective coating which is derived from a composition comprising (1) a urea aminoplast, (2) a vinyl modifying resin, (3) a polyol, and (4) a suitable catalyst, said protective coating being able to adapt to the bends of said wear layer and improving has scratch and stain resistance in relation to the untreated wear layer.

Such a coating can be formed on a release surface and thermally cured. A cross-linkable wear layer composition such as a polyurethane composition is then poured onto the cured layer and cross-linked, after which the assembly is transferred to a support surface. Surface coatings are manufactured which exhibit amazing resistance to conventional household stains and also improved scratch resistance.

The present invention therefore relates to a surface coating and in particular a floor covering comprising polyurethane or other wearing layers with a coating of urea aminoplast which is at least partially etherified with alkyl groups having 4-10 carbon atoms, a vinyl modifying resin, a polyol, and an acid catalyst. .

Second, the present invention relates to a method of providing a wear layer for a resilient surface coating, as described above according to the invention, the method comprising the steps of: providing a release carrier comprising a support surface and a release coating; applying to said release coating a composition comprising .8703120-4- (1) a urea aminoplast, (2) a vinyl modifying resin, (3) a polyol, and (4) a suitable catalyst; At least partially thermally curing said composition; applying a cross-linkable wear layer composition to said urea aminoplast layer; curing said wear layer; 1 ° laminating said wear layer to a resilient support structure and separating said release wearer from the wear layer, said surface coating comprising a wear layer with a protective coating, the protective coating being flexible and scratch and stain resistant as compared to an untreated wear layer.

The resilient surface coatings that can be made according to the present invention are related to those known in the art. They may therefore include an underlying resilient support typical of those used to manufacture vinyl floor covering structures. Carriers of this type may be derived from backing materials, plastisols, foamed plastisols, randomly distributed vinyl particles, screen printed vinyl particles, and the like, the selection of such materials being within the skill of the ordinary artisan.

The surface coatings also include 50 composite * wear layer compositions. The major portion of the wear layer will include materials currently known in the art. Examples of such materials are cross-linked wear layers derived from urethanes, acrylated or methacrylated urethanes, unsaturated 55 polyesters and the like which are all known. Such wear layers can be cross-linked by moisture curing techniques, thermally induced free radical curing techniques, oxidative curing techniques, radiation curing techniques, or a combination thereof.

The novelty of the present invention lies in the presence of a second protective layer on the conventional wear layer components. This second material is derived from urea aminoplast resin, a polyol, an acidic catalyst and a vinyl modifying resin and provides a flexible yet scratch and stain resistant top surface.

The resins that can be used to practice the present invention are hereinafter also referred to as "aminoplasts". Compared to melamine formaldehyde resins, these materials may be partially or substantially methylated and the methylol groups may be partially or fully etherified with methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl groups, isomers of these groups and mixtures thereof; however, preferably the aminoplast will be at least partially etherified with a relatively long chain alkyl group having 20 of 4-10 carbon atoms. The long chain portions of the urea aminoplast contribute to provide flexibility of the cured vinyl product. As for the urea-based resins, many of these aminoplasts are commercially available and are sold, for example, as Resimene resins by Monsanto Company.

The vinyl modifying resins to be used will be one or a combination of the resins known in the art. Examples of such resins are solution vinyl copolymer resins derived from vinyl chloride and vinyl acetate. Resins of this type are sold by Union Carbide and may or may not have a hydroxyl or other functionality.

One such resin is available under the trade designation VAGH. Others may include VAGD, VROH, and 35 VYES resins. Examples of other resins are specialty resins such as polyvinyl acetals (e.g. polyvinyl butyral) either alone or in combination with polyvinyl alcohol and / or polyvinyl acetate, and polyvinyl esters such as polyvinyl acetate. Such materials are known in the art because they are suitable for solution application; they are therefore distinguishable from dispersion type resins and general purpose resins which are substantially insoluble in the most common solvents. Essentially, the modifying resins should be suitable to increase the flexibility and strength of the cured compositions without adversely affecting stain resistance.

The polyols that can be used to practice the present invention are alcohols containing 2 or more alcohol groups. For example, 1,6-hexanediol, 1,4-cyclohexanedimethanol, glycerine, neopentyl glycol, tripropylene glycol, 1,4-butanediol, tri-methylolpropane, pentaerythritol, and many other polyols or esters of such polyols, such as the neopentyl glycol ester and the like can be used to practice the present invention, wherein said polyols are well known in the art.

The acidic catalysts which can be used to catalyze the thermal curing reaction between the vinyl modifying resin, the urea-aminoplast, the polyol and the wear layer surface are all known in the art. Examples of such catalysts are sulfonic acids, such as methanesulfonic acid and p-toluenesulfonic acid, and other acids such as citric, maleic, phthalic, and the like. The catalysts can be used in the free acid form, but they can also be stabilized, such as, for example, by using an amine to neutralize the acid. Examples of such amines are ammonia, di-isopropanolamine and 2-amino-2-methyl-1-propanol. The only limitation is that the catalysts must be tolerated by the other components of the system. Since these catalysts are all known to those skilled in the art, their choice will be within the skill of the ordinary artisan.

. 87 0 3 1 2 0 -7-

For the practice of the present invention, a release surface is provided for the urea-aminoplast composition. As the very smooth surface, a polished chrome plate or a release paper coated with a polyalkylene material can be used. A particularly good example of the latter is polypropylene matted by calendering. For less glossy surfaces, other types of coated papers or tapes may be used, examples of which are silicone, complexed chrome and methyl cellulose-treated papers or tapes. The choice of such materials is within the ability of the ordinary skilled artisan.

A layer of urea-aminoplast composition is poured onto the release paper. Although the component-15 ratios of the composition may vary considerably, the composition will usually comprise about 4-1 parts of the modifying resin on any 1-4 parts of urea aminoplast / polyol blend. Furthermore, the urea aminoplast polyol blend may comprise from about 5-1 parts of urea aminoplast to 20 every 1-5 parts of polyol. Preferably, however, 3f-1 parts of the modifying resin will be present for every 1-2 parts of urea aminoplast / polyol with the ratio of about 3: 1 parts of urea aminoplast for every 1-3 parts of polyol. Usually this composition will be present in an organic solvent; however, it is also possible to apply the composition in aqueous form.

After the urea aminoplast composition is applied to the release paper, it is dried and at least partially cured at about 250 ° F (121 ° C). Although it is possible to form the laminates of the present invention using partially cured aminoplast layers to obtain a high quality product, it is usually preferred to ensure that the aminoplast layer is fully cured before applying the urethane layer .

The crosslinkable wear layer coating composition can be applied directly to the aminoplast layer after the aminoplast layer has cured. It is noted, however, that those skilled in the art may optionally choose to pretreat the surface of the cured urea aminoplast layer with a corona discharge or to apply an adhesive layer composition 5 to promote adhesion between the layers. The latter compositions, which are typically vinyl lacquers, are widely used and are known to those skilled in the art. Such compositions include vinyl chloride copolymer solution resins such as the VAGH 10 resin as described above.

Corona discharge is also known in the art and causes an increase in surface energy by exposing the surface to an electric arc discharge. The amount of energy required to promote good adhesion can be quickly determined in a standard manner. The surface tension of the coating composition can thus be determined according to ASTM D 1331 and the surface energy of the surface to be coated can be determined essentially as described in ASTM D 2578. The aim is to determine the surface energy of the surface to be coated. increase that it is wetted by the coating composition. Ideally, the surface energy resulting from the corona treatment will be at least 25 10 dynes / cm higher than the surface tension of the coating composition

The coating thickness of the wear layer composition may range from 25-200 µm, but will preferably range from 62.5 µm to about 112.5 µm. The composition 30 may be a low solids solution (e.g. 40%) of a moisture curable polyether or polyester based urethane or it may comprise a two component system such as a polyester having a hydroxyl functionality in combination with 35 diisocyanate. The latter composition is cured by reaction of the diisocyanate with the hydroxyl groups of the polyester as well as with the moisture from the air. Otherwise, radiation-curable or. 87 0 3 1 2 0 -9- combined under the influence of radiation and moisture-curing constituents are used. As with the aminoplast layers, it is also recommended to ensure that the urethane layer is fully cured before the lamination 5 is applied to the resilient surface coating. *

When fully cured materials are manufactured and then laminated to resilient surface coatings, poor adhesion of the laminate to the surface coating has sometimes been observed.

Both with aminoplast layer and wear layer, it has been found desirable to avoid the lamination problems by providing an adhesive layer between the (exposed) back surface of the wear layer and the resilient layer 15 against which it abuts. As an alternative, a corona discharge treatment is also available to facilitate the adhesion of the coatings.

The upward-facing wear layer is coupled to the surface layer of the resilient support, with or without an intermediate bonding layer or corona discharge treatment, and the composite material is then subjected to heat and pressure to ensure good adhesion. The composite material may also be adhered in the same manner to granular or hard-pressed screen printing vinyl products.

After the curing is complete, release paper is taken from the hot sample to form a decorative surface coating that exhibits good scratch and stain resistance. The materials are therefore resistant to stains from household items such as lipstick, mustard, shoe polish, food coloring and the like.

The present invention will be better understood by the following examples.

These examples are given by way of illustration and not by way of limitation.

.8703120 r -10- EXAMPLES Example 1

The following compositions have been prepared in which each of the indicated ingredients is in parts by weight 5.

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Each of a series of polypropylene coated release papers was coated on samples 1-1 to 1-5 with a wet thickness of about 62.5 to 87.5 µm using a reversal roller coater. The coated paper was then passed through an oven at 260 ° F (127 ° C) so that the coating remained in the oven for 4 min.

A moisture curable polyurethane coating composition as shown in Table 2 was prepared to be applied to the coated release papers.

Table 2

Ingredient weight (grams)

Folyether diol (Union Carbide LHT 240) 40.80 15 Folyether diol (Union Carabide LHT 112) 14.20

Xylene solvent 110.00

Toluene solvent 46.00

Dimethyltin dineodecanoate catalyst (Witco UL-28) 0.55 20 Surfactant (Monsanto XA-677 Mult if lew) 0.30

Light stabilizer (American Cyanamid UV-5411) 0.20

These ingredients were placed in a stirred nitrogen purged glass reactor and heated to 70 ° C for 1 hour. 44.90 g of 4,4'-dicyclohexylmethane diisocyanate was added dropwise over a period of 30 min at a rate sufficient to maintain the temperature of the mixture at 70 ° C. After a further 2 hours of stirring and heating at 70 ° C, the product was cooled.

On each of the aminoplastic coated release papers, a wet coat 25-62.5 µm thick of an adhesive lacquer was applied comprising 18.54 wt% VAGH resin, 0.37% Thermolite 31, 0.0094% UVitex 35 OB and 81.08% methyl isobutyl ketone solvent. The coated sample was then dried in ambient air or under slight heating to remove the solvent.

After completion of the drying, each paper was coated with a wet layer thickness of 125-162.5 µm of the moisture curable polyurethane material as described above. The coated samples were then passed through an oven at 250 ° F (121 ° C) to dry the sample 5 completely, the residence time in the oven being 7 min.

Coatings of samples from 1-6 to 1-9 were prepared on polypropylene coated paper using a drawn No. 30 wire-wrapped rod to obtain coatings of 12.5 .mu.m thickness after drying. The samples were then cured at 250 F (121 C) for 5 mm. Sample 1-6 delaminated completely and was discarded. The remaining samples were coated with a moisturizing polyurethane coating composition as indicated above.

The lamination and hardening steps for laboratory evaluation involve the use of a 300x 300 mm press to produce 225x225 mm samples. The top plate of the press was heated to 310 ° F (154 ° C) while the bottom plate was heated to 300 ° F (149 ° C). The residence time in the press was 10 sec at a 250 lb (17.25 bar) pressure followed by 10 sec at 1200 lb (82.8 bar) pressure. Following removal of the sample from the press, the hot sample release paper was peeled off.

Both screen printed vinyl and gelled vinyl plastisol type resilient support materials can be used for lamination with the above coatings and stain resistance could be determined using known household stains. Although specimens 1-7 were clearly more sensitive to stains than the others, all specimens exhibited a special resistance compared to the untreated polyurethane material and also showed good scratch resistance.

. 87 0? 126

Claims (13)

Resilient surface coating comprising a resilient support and an adhered cross-linked wear layer, characterized in that the top surface of said wear layer comprises a protective coating 5 derived from a composition comprising (a) a urea aminoplast, (b) a vinyl modifying resin , (c) a polyol, and (d) a suitable catalyst, wherein said protective coating is able to adapt to the bends of said wear layer, and has improved scratch and stain resistance relative to the untreated wear layer. Surface coating according to claim 15, characterized in that said wear layer is derived from materials selected from the group consisting of urethanes acrylated urethanes, methacrylated urethanes and unsaturated polyesters. Surface coating according to claim 20. or 2, characterized in that said vinyl modifying resin is a soluble vinyl copolymer resin. Surface coating according to claim 3, characterized in that said resin is derived from vinyl chloride and vinyl acetate. Surface coating according to claim 1 or 2, characterized in that said modifying resin is selected from the group consisting of polyvinyl acetal, polyvinyl ester and a combination of polyvinyl acetal with polyvinyl alcohol or a polyvinyl ester. Surface coating according to any one of claims 1 to 5, characterized in that the composition contains 4-1 part of modifying resin on every 1-4 parts of urea aminoplast / polyol mixture, the mixture of 5-1 part of urea aminoplast on every 1-5 parts. polyol. Surface coating according to claim 6, characterized in that the composition contains 3 ^ -1 part modifying resin on every 1-2 parts urea aminoplast / polyol mixture. 87 0 3 12 C Λ, the mixture containing 3-1 part urea aminoplast for every 1-3 parts polyol. Surface coating according to any one of claims 1-7, characterized in that the adhesion between the wear layer and said aminoplast layer is improved by an adhesive coating layer. Surface coating according to any one of claims 1-7, characterized in that the adhesion between the wear layer and said urea aminoplast layer is improved by a corona discharge pretreatment of said urea aminoplast layer. 10. A method of providing a wear layer for a resilient surface coating according to any one of claims 1-9, characterized in that said method comprises the steps of: providing a release support comprising a support surface and a release coating, applying to said release coating of a composition comprising, (a) a urea aminoplast, (b) a vinyl modifying resin, (c) a polyol, and (d) a suitable catalyst, at least partially thermosetting of said composition, applying a cross-linkable wear layer composition to said urea aminoplast layer. curing said wear layer, laminating said hardened wear layer 30 on a resilient support structure and separating said release wearer from the wear layer, the surface coating comprising a wear layer with a protective coating, the protective coating being flexible and scratch and stain resistant as compared to an unhandy divided 35 wear layer. A method according to claim 10, characterized in that an adhesive coating layer is provided between said wear resistant layer and said aminoplast layer. , 8703120 -iT- A method according to claim 10, characterized in that said urea aminoplast layer is subjected to a corona discharge before said abrasion resistant layer is applied to said urea aminoplast layer. A method according to claim 10, characterized in that the urea aminoplast layer is fully cured before the wear layer composition is applied thereto. . 8? 0 3 1 2 C