Method for Producing an Unbacked Tension Floor

1. Field of the Invention

The field of the invention relates to decorative thermoplastic vinyl resin-containing sheet surface coverings or flooring which may be installed such that they have a tension built in on installation.

2. Description of the Prior Art

It has been recognized in the prior art that stresses sometimes built into commercial thermoplastic vinyl resin-containing decorative sheet floor coverings may sometimes be taken advantage of in that the tension caused by the stresses may be used, utilizing certain installation techniques, to create an installed floor product having a self-induced tension built in therein. Examples of such installations are disclosed in Deichert et al, U.S. Pat. No. 3,464,178 and Evans U.S. Application Ser. No. 153,872 filed June 16, 1971. It is also known from Hassel U.S. Pat. No. 2,913,773 to consolidate a homogeneous vinyl resin composition decorative layer to a strippable backing after which the backing is removed and from Adams U.S. Pat. No. 2,920,977 to apply a film to a strippable backing after which a cellular vinyl layer is applied to the film. Neither Hassel nor Adams suggests that a self-induced tension floor installation could be achieved with their products.

In accordance with my invention, I have provided an unbacked decorative thermoplastic vinyl resin-containing sheet surface covering having at least two distinct thermoplastic layers wherein the compositions and thicknesses of such layers are such that, on rolling the sheet, the layer facing outward in the roll is stretched to a degree greater than the degree to which the other layer is compressed. On unrolling the sheet, the sheet is placed under tension by the stresses set up therein by the opposing stretching and compressive forces, these forces stretching the surface covering to a dimension greater than its original dimension. When the sheet is installed before tension has been relieved, a self-induced tension is built into the installed sheet and this acts to maintain the sheet flat even on a wood substrate that is subjected to a fluctuating environment.

In a copending application, Ser. No. 153,872, filed June 16, 1971 and now abandoned, I have described a method of installing a resilient decorative thermoplastic surface covering wherein a vinyl resin-containing composition is fused under heat and pressure to a thermally dimensionally stable strippable backing layer with the backing layer maintaining the fused thermoplastic wear layer under tension until ready for installation. At the installation site, the backing is stripped and the wear layer secured against movement with respect to the surface being covered only at its periphery. The installation is completed before stresses in the wear layer are relieved and a self-induced tension is built into the wear layer keeping it flat even on a wood substrate that is subjected to a fluctuating environment.

I have now discovered that an all thermoplastic sheet consisting of two or more thermoplastic layers may be constructed such that, when rolled for transporting, and unrolled for installation, it also will have a self-induced tension built therein when installed by securing it at its periphery against movement with respect to the surface being covered. This results in an obvious advantage over the invention described in my copending application in that no backing has to be stripped from the thermoplastic sheet at the installation site prior to cutting the sheet to size and installing the sheet.

As described herein, the thermoplastic decorative or wear layer means the decorative wear layer, per se and any protective clear coat which may be applied thereto.

In accordance with my invention, a carrier such as paper or felt carrying a release coating thereon is coated with a vinyl resin-containing coating which may be compounded to the degree required to give it the desired compression or elongation characteristics after which a separate and distinct decorative vinyl resin-containing layer is applied thereover and the whole consolidated and fused to form two distinct thermoplastic vinyl resin-containing layers. As the resins used, I prefer to use plasticized poly(vinyl chloride), either the homopolymers or copolymers customarily used in the manufacture of decorative thermoplastic coverings of the type currently commercially available, and I have found that I may form these layers with conventional plastisols and/or conventional dry blending resin formulations. The only critical factor of which I am aware are the adjustments that must be made as to the thicknesses of the two distinct layers and adjustments between resins, fillers, plasticizers, etc. used in formulating so as to achieve the desired results when the sheet is rolled, whereby the outward facing layer is stretched and the other layer compressed when the sheet is in a rolled form. The several parameters must be adjusted such that, when the sheet is rolled, the outward facing layer is stretched to a degree which is greater than the degree to which the other layer is compressed. That is, when the sheet or surface covering is unrolled, the elongated layer must overcome the compressed layer such that the surface covering is initially stretched to a dimension greater than its original unrolled dimension. The respective layers may be so designed that the sheet may be rolled with the decorative layer facing outward or inward in the roll depending on the elongation and compression characteristics of said layers.

After the thermoplastic sheet surface covering has been formed in accordance with this invention, it is stripped from the strippable carrier and rolled so that stresses are built into the sheet by the above-described stretching and compressing forces acting on the layers while the sheet is in rolled form.

As is the usual custom, the sheet is shipped to the installation site where it is unrolled, cut to size and installed. When the sheet is installed, and before the stresses therein are relieved, by securing the sheet along the periphery thereof and over the surface to be covered, the stresses set up in the sheet create a built-in self-induced tension such that the sheet is unaffected even on a wood substrate that is subjected to a fluctuating environment and remains flat on the surface over which it is installed.

The following examples illustrate specific embodiments of the invention. In the examples, PVC means poly(vinyl chloride) and MN means average molecular weight.

A carrier is coated with a release coating and dried. This release coating is applied to the carrier using a forward roll coater and then air dried.

Seven mils of a filled plastisol base coat are applied to the release coated carrier using a reverse roll coater. This coating is then gelled in an oven to 290.degree. F.

Twenty-one mils of plastisol foam are applied on top of the base coat using a reverse roll coater and this is gelled in an oven to 270.degree. F.

The gelled foam is then printed with standard inks in the desired design on a Rotogravure Press. A standard ink formulation is as follows:

In the above formulation, the Plastoprint Solvent is a mixture of 77 percent by weight 2-nitropropane, 13 percent by weight diacetone alcohol and 10 percent by weight isopropyl acetate. The Plastoprint Extender is a solution of a poly(vinyl chloride-vinyl acetate) copolymer (between about 3 and 8 percent vinyl acetate) in Plastoprint Solvent and the Plastoprint Clay Extender is Plastoprint Extender containing about 30 percent by weight clay. All of the pigments are mixed with Plastoprint Extender; the Plastoprint Brown containing about 21 percent by weight molybdate orange and 4 percent by weight molybdate black; the Plastoprint Medium Chrome Yellow containing about 29.8 percent by weight medium chrome yellow; and the Plastoprint Molybdate Orange containing about 30 percent by weight molybdate orange.

Fourteen mils of a clear plastisol are applied using a reverse roll coater and then the decorative surface covering heated to 385.degree. F. causing the blowing agent to decompose to foam the foam layer and to fuse the clear coat.

The release carrier is stripped from the product, and is utilized as a slip sheet with the product being wound on a seven inch core in roll form.

A carrier is coated with a release coating and dried in the same manner as set forth in Example 1.

A reverse roll coater is used to apply seven mils of a plastisol base coat to the release carrier. This coating is then gelled in an oven to 290.degree. F.

The base coat is then coated with a very thin layer of a clear plastisol that is applied with a rotary screen printer.

A dry blend 28 mils thick is metered onto the wet plastisol coat and the dry blend is then sintered at 350.degree. F.

Foamable plastisol inks are printed into the sintered dry blend in the desired design and those areas not printed are then printed with non-foamable plastisol inks using a Zimmer Printer. The inks are then gelled at 270.degree. F.

The foamable ink contains 20.72 parts by weight paste and 400.00 parts by weight paste foamable ink.

The structure is then coated with a clear plastisol using a reverse roll coater and heated to 385.degree. F. to fuse the resins and expand the pattern in the areas printed with the foamable inks.

The release carrier is stripped from the product and can be utilized as a slip sheet when rolling up the product.

The following tables report the amounts the decorative layers are stretched and the backing layers compressed while in roll form and the change in dimensions of the surface covering on unrolling. Table I shows measurements for the decorative surface covering produced in accordance with Example 1 and Table II shows measurements for the decorative surface covering produced in accordance with Example 2. Measurements were made lengthwise on the respective surface coverings.

When floors produced in accordance with Examples 1 and 2 were unrolled and installed over a wooden subfloor and before the sheets could substantially return to their original dimensions, by stapling the sheets at their peripheries to the subfloor, the sheets remained taut and flat even in a fluctuating environment.

When sheet flooring produced in accordance with Examples 1 and 2 was rolled inside out, that is with the decorative layers facing inwardly in the roll, the sheets grew on unrolling and buckled in a fluctuating environment when installed by securing the sheets at their peripheries over a wooden subfloor.