Embossed surface covering having enhanced three-dimensional effect

[57] ABSTRACT

Process of making a decorative surface covering by applying a first printing to a suitable backing followed by coating the printed backing with a transparent (after fusion), resinous coat. A second printing is applied to the transparent coating, the printing composition containing a blowing agent that will penetrate into the transparent coating. On subsequent fusion and decomposition of the blowing agent, raised cellular areas occur in regions where the blowing agent composition was printed.

Claims, 3 Drawing Figures

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PATENTE0APR301974

3.808.024

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PRODUCT

3,808,024 .-1

EMBOSSED SURFACE COVERING HAVING ENHANCED THREE-DIMENSIONAL EFFECT

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to decorative surface coverings, and more particularly to decorative floor and wall coverings. Still more particularly, the invention relates to decorative, flexible, embossed floor and wall coverings presenting a novel and unusual appearance to the eye.

In all fields of interior decoration, and particularly in the floor covering field, there is always a need for special, unusual, and pleasing decorative effects.

2. Description of the Prior Art

British Pat. No. 1,194,490, sealed Oct. 7, 1970, and U.S. Pat. No. 3,399,106, issued Aug. 27, 1968, both contemplate printing on flexible vinyl resin systems with a blowing agent adapted to penetrate the system. On subsequent heating and fusion, the sheet develops cellular raised areas in those regions where the blowing agent occurs, thus raising those areas in contrast to unprinted areas. However, neither of these patents contemplates a decorative system wherein the decorative elements actually lie on two completely different levels in the system.

U.S. Pat. No. 2,920,977, issued Jan. 12, 1960, contemplates printing with a blowing agent on a backing, but again, does not contemplate a two-level decorative system.

SUMMARY OF THE INVENTION

Any suitable design, or a homogeneous layer, may be printed with pigments or dyes onto a backing such as a cellulosic or asbestos felt of the type commonly used in the floor covering industry. This design or layer will be visible in large part in the final product. The printed backing is coated with a vinyl resin plasticized system to cover entirely the printed sheet with a film having a preferred thickness in the range of 2-10 mils. On top of this plasticized vinyl resin system coating, which is transparent after fusion, a second design is printed with an ink composition which contains a blowing agent which will penetrate into the coating. As a preferred embodiment, the blowing agent will penetrate to about 90 percent of the total thickness of the transparent coating. A protective top clear coat may be applied if desired. The system is then subjected to sufficient heat in the range of about 300°-450° F. to fuse the resin system and to decompose the blowing agent in those regions where it has been printed. The final product will then present an embossed appearance by virtue of a cellular structure formed in the regions where the blowing agent occurs. Additionally, the first design will be visible through the clear coat in all areas where the blowing agent composition was not printed, and can even by seen through the cellular structure in the region where the blowing agent occurred provided no obscuring pigment or dye was used in the blowing agent printing composition. Where the blowing agent has penetrated into the clear transparent sheet a distance in the range of about 20-90 percent of the total thickness of the sheet, the eye will actually be able to see under and around the raised regions of cellular structure, thus imparting to the overall appearance of the surface covering a vivid and striking three-dimensional effect.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an enlarged, simplified, cross-sectional view of the product prior to fusion,

FIG. 2 is an enlarged, simplified, cross-sectional view of the fused product having a clear coat as a top layer, and

FIG. 3 is a flow diagram illustrating the process of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The backing to be used in the present invention will be any of those backings normally used in the floor covering industry, or any other similar and suitable backing which can bear printed designs and flexible films.

Normally, the surface of the backing will be coated with a composition adapted to fill the spaces between the fibers in order to present a good printing surface. This fill coating composition may be printed on the surface, or it may be doctored, sprayed, roll coated, or otherwise applied in any convenient and inexpensive thickness. Where this coating composition is pigmented, any suitable color may be used, although generally speaking, the simplest and most inexpensive composition will be white. A binder of casein or acrylic or a vinyl resin may be used, and drying or curing, perhaps followed by calendering, will often take place. Such printable coatings on the surface of flooring felt are well known in the art.

The first design to be printed on the backing may be printed by screen printing, block printing, or more preferably, by rotogravure printing. The designs that may be used in the printing of this first design are virtually limitless. The usual ink compositions customary in such printing will be utilized in the present process. Such printing is well known in the flooring art. A solid, pigmented layer may be applied in lieu of an interrupted design. The fill coating, described above, may serve as the first decorative layer.

The printed backing is next coated with a clear, transparent film of plasticized vinyl chloride resin. The resin may be a homopolymer or vinyl chloride or a copolymer, most usually a vinyl chloride-vinyl acetate copolymer. Such clear coat formulations in the flooring art are well known. In addition to the plasticizer and vinyl resin, the composition will contain heat and/or light stabilizers for the resin. Tinting of the composition may be utilized provided the coating remains clear so that the first-printed design may be seen through it. The film thickness will be in the range of about 2-10 mils, with a preferred range of about 5-10 mils. A preformed film of plasticized poly(vinyl chloride) may be placed over the printed backing, or a plastisol or organosol composition may be doctored^ curtain coated, reverse roll coated, or otherwise applied over the printed backing. The plastisol and organosol films do not become clear until sufficient heat has been applied to fuse or gel them. If latices are used to supply the coating, drying will follow. If plastisols or organosols are used, the system should be heated in order to fuse or gel the coating composition to render it tough, strong, adherent, transparent and ready to receive the printed design which constitutes the next step in the process. If preformed films are laid on the printed backing, heat and pressure

3,808,024 will normally be required to firmly adhere the film to the printed backing.

A printed design is then applied to the transparent coating composition. The printed design may in a manner known in the designers’ art be complimentary to the first-printed design first placed on the backing. The second-printed design will not normally cover the entire surface of the clear coating, and it may be an independent design in the sense that it needs no registration during the printing operation with the first-printed design on the backing. The second printing composition must contain a blowing agent adapted to penetrate into the transparent layer. Any suitable blowing agent which will decompose in the range 300°-450° F. will suffice so long as it will penetrate into the clear layer. These blowing agents yield a gas on heat decomposition. The gas is usually nitrogen. Among the blowing agents which may be used are the azo esters such as diethylazodicarboxylate, diisopropylazodicarboxylate, and diethylene bis(ethyl azocarboxylate). These blowing agents will normally be used in the presence of solvents for the vinyl composition which makes up the clear, transparent layer on which the blowing agent composition is printed. Thus, tetrahydrofuran, dimethylsulfoxide, ketones, and hydrocarbons may be used with or without thickeners to speed or slow the rate of penetration of the liquid blowing agent and to give to the blowing agent composition the desired viscosity for application to the gelled sheet. Solid blowing agents may be used, and in fact, the solid azodicarbonamide (azobisformamide) is the preferred blowing agent in the present invention. Other potential blowing agents to be used are azobisisobutyronitrile, N,N'-dimethylN,N'-dinitrosoterephthalamide, ρ,ρ'-oxybis (benzene sulfonylhydrazide) and dinitrosopentamethylene tetramine. These solid blowing agents are not soluble in any component of the clear, transparent sheet, but if they are sufficiently finely divided and are carried by a solvent or swelling agent for the vinyl resin composition, they will penetrate the sheet and give rise to a cellular structure on heat decomposition. The very finely divided particle size of these solid blowing agents is accomplished by preparing the printing composition on an ink mill or paint mill. It is a preferred embodiment of the present invention that the blowing agents do not penetrate the complete thickness of the clear, transparent coating composition. A maximum penetration of about 90 percent of the total thickness is preferred, and about 50 percent penetration is ideal. Since penetration should be at least about 10 percent to achieve significant cellular structure, the range of penetration of the blowing agent in the preferred embodiment of the present process is about 10-90 percent of the total thickness of the clear sheet. With such penetration, the bottom portion of the clear sheet remains solid and clear, thus enabling light to pass through that portion of the clear sheet, unobstructed and unscattered. Hence, when the finished product is viewed with the eye, one can actually see under the cellular structures. The striking and startling three-dimensional effect thereby achieved has not been duplicated elsewhere. Apparently, it arises by virtue of the fact that a portion of the clear sheet scatters and obstructs the passage of light therethrough, while another portion beneath the cellular portion is clear and does not scatter light, the first-printed design on the backing being visible underneath the actual cellular structure. The blowing agent ink composition may be dyed or pigmented if desired. If heavily pigmented, one will not be able to see the first-printed design through the cellular structure, but one can see under the opaque, cellular structure. This enhances the three-dimensional effect. However, the blowing agent ink composition may be transparent or tinted or lightly pigmented to achieve any desired degree of light transmission and to achieve the effect desired by the designer. The blowing agent composition will normally contain a blowing agent accelerator, or activator. These activators are well known in the art and a variety of them is available commercially. Many of them are metallic soaps. The principal metallic portions of the activators are zinc, lead and cadmium. The fatty acid portion of the soap will generally contain from seven to 18 carbon atoms. Soaps containing eight to 12 carbon atoms are preferred, and the octoate is primarily preferred. Lead octoate and zinc octoate have high activities as activators for reducing the decomposition temperature of many of these blowing agents. The blowing agent activator may be present in the transparent film instead of in the foamable ink. Although printing is the preferred method of applying the blowing agent composition, it may be applied by spraying or wiping through a stencil positioned against the surface of the sheet.

After printing or otherwise applying the blowing agent composition in the desired design, the printed sheet will normally be aged to allow penetration of the blowing agent into the clear, transparent film to which it has been applied. Liquid azo esters penetrate rapidly; normally no more than a few seconds is needed. Overnight aging is normally all that is needed even for use with the solid blowing agents. If desired, gentle heat, insufficient to decompose the blowing agent, may be applied to aid penetration, or to control penetration.

After application of the blowing agent ink composition, and after any aging, a final clear coat may be applied over the entire system in order to serve as a wearresistant layer. These clear coats are well known in the art and frequently comprise poly (vinyl chloride) plastisols containing small amounts of solvents to aid in controlling the thickness of the film. The final clear coat thickness may measure in the range of about 1-15 mils, and is applied by conventional and well known methods.

The system is then ready for the final heating step. The system is subjected to heat in conventional manner in the range of 3OO°-45O° F. in order to complete any final fusion of the vinyl resins if needed, and in order to decompose the blowing agent and form a cellular structure in the clear, transparent sheet to which the blowing agent ink composition has been applied. While hot air ovens are preferred for the final heating step, other methods such as infrared lamps, resistance heaters and the like may be used. On cooling, a striking design effect will be manifest, particularly in the preferred embodiment wherein the eye can see under and around the raised areas of cellular structure which exists in the clear, transparent film.

Referring to FIG. 1, the backing 1 has the firstprinted design 2 thereon, and the clear, transparent film 3 overlies the first-printed design 2. The blowing agent ink composition 4 lies on top of the clear, transparent film 3 before penetration. Referring to FIG. 2, the backing 1, the first-printed design 2, and the clear coat 3 appear as in FIG. 1 except that the printed ink

3,808,024 composition 4 of FIG. 1 has, after penetration and heating, produced the cellular structure 5 in FIG. 2. The top clear coat 6 serves as a protective wear layer for the system.

The following examples illustrate several embodiments of the invention. All parts are by weight unless otherwise stated.

EXAMPLE 1

A first design was printed on a smooth, beater saturated asbestos sheet backing using an ink of the following composition:

Ingredients Parts

<td> Solution ink base - clear ‘°</td><td> 7.0</td>

<td> Solution ink base - pigmented ¹²¹</td><td> 15.1</td>

<td> Alkyl aryl polyether surfactant</td><td> 1.0</td>

<td> Methyl isobutyl ketone</td><td> 29.4</td>

<td> Cellosolve acetate</td><td> 19.6</td>

<td> Silica</td><td> 3.0</td>

<td> Metallic pigment</td><td> 23.0 .</td>

<td> (1) Poly (vinyl chloride-acetate) solution (29% resin) (2) Poly(vinyl chloride-acetate) solution (15% resin.</td><td> 30% silica)</td>

<td> The printed sheet was coated with sol having the following formula:</td><td> a deaerated plasti</td>

<td> Ingredients</td><td> Parts</td>

<td> Poly(viny) chloride) resin</td><td> 100.0</td>

<td> Dioctyl phthalate plasticizer</td><td> 41.5</td>

<td> Butyl benzyl phthalate</td><td> 10.0</td>

<td> Epoxidized tallate plasticizer/stabilizer</td><td> 5.0</td>

<td> Zinc octoate type activator/stabilizer</td><td> 3.0</td>

Gellation was carried out by heating^the sheet for 2 minutes at 275° F. to produce a clear film 0.012 inch thick.

A second design was printed on the clear film with a foamable ink of the following composition:

<td> Ingredients</td><td> Parts</td>

<td> Solution ink base - clear &gt;</td><td> 45.0</td>

<td> Azodicarbonam ide/dibutyl phthalate,</td><td> 37.5</td>

<td> 40/60 paste</td><td></td>

<td> Alkyl aryl polyether surfactant</td><td> 0.75</td>

<td> Tetrahydrofurari</td><td> 20.0</td>

<td> Cyclohexanone</td><td> 65.0</td>

<td> Pigment/DOP paste (58% TiO₂)</td><td> 8.6</td>

<td> Pigment/DOP paste (60% pigment)</td><td> 9.2</td>

<td> Silica</td><td> 4.0</td>

(l) Poly(vinyl chloride-acetate) solution (29% resin)

A clear coat of the following formula was mixed on a paint mill and then applied:

Ingredients Parts

<td> Poly(vinyl chloride) resin, dispersion grade</td><td> 75</td>

<td> Poly(vinyl chloride) resin, blending grade</td><td> 25</td>

<td> Butyl benzyl phthulute</td><td> 15</td>

<td> Dioctyl phthalate</td><td> 17</td>

<td> Epoxidized tallate</td><td> 3</td>

<td> Calcium-zinc stabilizer</td><td> 2.5</td>

<td> Texanol isobutyrate</td><td> 15</td>

Final fusion was carried out at 375° F. for 3 minutes to produce a product having a stark, three-dimensional appearance due to the fact that the first printed design was visible under the cellular structure in the regions where the blowing agent had been printed.

EXAMPLE 2

An attractive visual effect was obtained by applying a white, aqueous paint to a beater saturated asbestos sheet backing, drying the paint, and applying and gelling the deaerated plastisol of Example 1. A tile design was printed on the transparent film using the foamable ink of Example 1. An additional amount of the foamable ink was pigmented with a different color and was also printed on the transparent film to add a texture to the tile design.

After clear coating and fusion as in Example 1, there resulted a floor covering having a strong threedimensional appearance in which the deep-set white paint appeared as the grout line in a tile having a tile background and raised texture accents at different levels.