Abstract:
An unbacked decorative thermoplastic vinyl resin containing surface covering having a self-induced tension is manufactured by (1) fusing a vinyl resin composition decorative layer and a vinyl resin composition backing layer to a strippable dimensionally stable backing to form a fused thermoplastic decorative surface covering, and (2) removing the strippable backing and rolling the surface covering, thus placing the surface covering under tension and thereby elongating the outward facing layer and compressing the other layer. The composition and structure of the outward facing layer is such that, on unrolling the surface covering, the elongated layer overcomes the compressed layer and the surface covering is stretched to a dimension greater than its original unrolled dimension. On securing the surface covering at its periphery only, the tendency of the surface covering to return to its original dimension, i.e. its elastic memory, creates a self-induced tension therein.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of application Ser. No. 606,449, filed Aug. 21, 1975, now abandoned, which is a continuation of application Ser. No. 524,562, filed Nov. 18, 1974, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     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. 
     SUMMARY OF THE INVENTION 
     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. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     EXAMPLE 1 
     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. 
     
         ______________________________________Release Coat                       Parts byIngredient                  Weight______________________________________Methocel, 15 cps. (Methyl Cellulose)                       525Water                       5272Crushed Ice                 800Polyglycol P-1200 (Polypropylene Glycol MW-1200)                       7.4White Pigment (T.sub.1 O.sub.2)                       65.0Green Pigment (Iron Nitroso Beta Naphthol Pulp)                       35.0______________________________________ 
    
     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° F. 
     
         ______________________________________Base Coat                       Parts byIngredient                  Weight______________________________________Tenneco 1732 (Dispersion PVC HomopolymerResin MW-106,000)           625.0Diamond PVC-71 (PVC Homopolymer ResinMW-139,000                  625.0Tenneco 501 (Blending Resin MW-95,300, Poly(vinyl chloride - vinyl acetate) CopolymerResin - 95.5% vinyl chloride, 4.5% vinylacetate)                    1250.0DOP (Di-2-Ethylhexyl phthalate)                       400.0White Paste (50/50 DOP/T.sub.1 O.sub.2)                       249.0Black Pigment (Carbon black)                       1.0Drapex 4.4 (Cetyl Epoxy Tallate)                       125.0TXIB (2-2-4 Trimethyl-1,3 PentanediolMonoisobutyrate ester)      250.0V-1366 (Ba. Ca. Zn. Phosphite)                       125.0Peg 200 (Polyethylene Glycol Monolaurate)                       50.0Camel Carb. (Calcium Carbonate)                       1000.0SMS (Mineral Spirits)       62.5______________________________________ 
    
     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° F. 
     
         ______________________________________Foam                       Parts byIngredient                  Weight______________________________________Exon 605 (Dispersion PVC Homopolymer ResinMW 80,400)                  1200Stauffer SCC-20 (Dispersion PVC HomopolymerResin MW 114,000)           500Geon 120 × 251 (PVC Homopolymer Resin)                       320Goodyear M-70 (Blending PVC Homopolymer ResinMW-81,100)                  700Drapex 4.4 (Octyl Epoxy Tallate)                       30DOP (Di-2-Ethylhexyl phthalate)                       1546T-3603 (Ba. Zn. Neodecanoate)                       284LU-390 (Aluminum Silicate)  350______________________________________ 
    
     The gelled foam is then printed with standard inks in the desired design on a Rotogravure Press. A standard ink formulation is as follows: 
     
         ______________________________________                      Percent byIngredient                 Weight______________________________________Plastoprint Extender (5-Q-211)                      5.24Plastoprint Clay Extender (10-Q-948)                      5.24Plastoprint Solvent        17.48Triton X-100 (Alkylated Acryl Polyether Alcohol)                      0.87Plastoprint Brown (80-Q-860)                      31.47Plastoprint Medium Chrome  15.73Yellow (20-Q-210)Plastoprint Molybdate Orange (30-Q-149)                      19.23Polyethylene Wax Dispersion                      4.74______________________________________ 
    
     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° F. causing the blowing agent to decompose to foam the foam layer and to fuse the clear coat. 
     
         ______________________________________Clear Coat                      Parts byIngredient                 Weight______________________________________Tenneco 1742 (Dispersion PVC Homopolymer ResinMW-120,000)                1920.0Tenneco 521 (Poly(vinyl chloride - vinyl acetate)Copolymer Extender Resin MW-75,900, 95.5%vinyl chloride, 4.5% vinyl acetate                      1280.0Drapex 4.4 (Octyl Epoxy Tallate)                      160.0DOP (Di-2-Ethylhexyl phthalate)                      384.0TXIB (2-2-4 Trimethyl-1,3 PentanediolMonoisobutyrate ester)     160.0Nuostabe V-1060 (Ba, Cd, Zn Compound)                      96.0Nuopaz 1046 (2-2-4 Trimethyl-1,3 PentanediolMonoisobutyrate ester)     864.0______________________________________ 
    
     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. 
     EXAMPLE 2 
     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° F. 
     
         ______________________________________Base Coat                      Parts byIngredient                 Weight______________________________________Exon 6337 (PVC Homopolymer Dispersion ResinMw-141,000)                400Blacar 1738 (PVC Homopolymer Dispersion ResinMW-233,000)                1250Blacar 501 (PVC Homopolymer Blending ResinMW-95,300)                 1100DOP (di-2-Ethylhexyl phthalate)                      383TXIB (2-2-4 Trimethyl-1,3 PentanediolMonoisobutyrate ester)     383S-160 (Butyl-Benzyl Phthalate)                      205V-1366 (1% Ba., .8% Ca., .9% Zn, 5.4% P)                      77Pigment as required______________________________________ 
    
     The base coat is then coated with a very thin layer of a clear plastisol that is applied with a rotary screen printer. 
     
         ______________________________________Clear Plastisol                       Parts byIngredient                  Weight______________________________________Blacar 1732 (PVC Homopolymer Dispersion Resin)                       100DOP (di-2-ethylhexyl phthalate)                       32TXIB (2-2-4 Trimethyl-1,3 PentanediolMonoisobutyrate ester)      17M-275 (Organotin Stabilizer)                       2______________________________________ 
    
     A dry blend 28 mils thick is metered onto the wet plastisol coat and the dry blend is then sintered at 350° F. 
     
         ______________________________________Dry Blend                       Parts byIngredient                  Weight______________________________________Exon 9290 (PVC Homopolymer MW-83,900)                       250M-275 (Organotin Stabilizer)                       5DOP (Di-2-ethylhexyl phthalate)                       75Hi Sil 233 (Amorphous Hydrated Silicate)                       0.63______________________________________ 
    
     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° F. 
     The foamable ink contains 20.72 parts by weight paste and 400.00 parts by weight paste foamable ink. 
     
         ______________________________________Foamable Ink                     Parts byIngredient                Weight______________________________________Exon 605 (PVC Homopolymer Dispersion Resin MW-80,400)               2000DOP (Di-2-ethylhexyl phthalate)                     900Drapex 4.4 (Octyl Epoxy Tallate)                     40ABC-18 (Organic Zinc Complex)                     60                     3000______________________________________ 
    
     
         ______________________________________Paste                    Parts byIngredient               Weight______________________________________Kempore AF (Azodicarbonamide)                    90.1DOP (Di-2-ethylhexyl phthalate)                    128.7                    218.8______________________________________ 
    
     
         ______________________________________Non-Foamable Ink                      Parts byIngredient                 Weight______________________________________Blacar 1732 (PVC Homopolymer Dispersion Resin MW-106,000)               2100DOP (Di-2-ethylhexyl phthalate)                      252S-711 (C.sub.7 -C.sub. 9 -C.sub. 11 Mixture, Phthalates)                      630Synpron 744 (Ba. Zn. Phosphite Stabilizer)                      42                      3024______________________________________ 
    
     The structure is then coated with a clear plastisol using a reverse roll coater and heated to 385° F. to fuse the resins and expand the pattern in the areas printed with the foamable inks. 
     
         ______________________________________Clear Plastisol                      Parts byIngredient                 Weight______________________________________Exon 6337 (PVC Homopolymer Dispersion Resin MW-141,000)               550Blacar 1738 (PVC Homopolymer Dispersion Resin MW-233,000)               1360Blacar 501 (PVC Homopolymer Blending Resin MW-95,300)                816DOP (Di-2-ethylhexyl phthalate)                      550TXIB (2-2-4 Trimethyl-1,3 Pentanediol Monoisobutyrate ester)    408S-160 (Butyl Benzyl phthalate                      217Synpron 744 (Ba. Zn. Phosphite Stabilizer)                      81.6______________________________________ 
    
     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. 
     
                       TABLE 1______________________________________    Elapsed           Wear Layer   Backing          Time     18    46     18    46          After    Inch  Inch   Inch  InchDate   Time    Unroll   Mark  Mark   Mark  Mark______________________________________Initial Marks   17.997  45.996   18.000                                  45.999Measurement on Core.           18.266           17.749Unrolled7-3-74 8:36    1 min.   18.050                         46.073 18.042                                      46.070  8:40    5 min.   18.038                         46.053 18.032                                      46.049  8:50    15 min.  18.032                         46.038 18.026                                      46.036  9:05    30 min.  18.028                         46.030 18.025                                      46.033  9:35    1 hr.    18.025                         46.020 18.022                                      46.024  10:35   2 hr.    18.023                         46.020 18.020                                      46.021  1:35    5 hr.    18.022                         46.017 18.019                                      46.0197-8-74 11:35   123 hr.  18.004                         45.986 18.000                                      45.9837-16-74  8:35    312 hr.  18.001                         45.975 17.998                                      45.9797-22-74  8:35    456 hr.  17.996                         45.961 17.991                                      45.962______________________________________ 
    
     
                       TABLE II______________________________________    Elapsed           Wear Layer   Backing          Time     18    46     18    46          After    Inch  Inch   Inch  InchDate   Time    Unroll   Mark  Mark   Mark  Mark______________________________________Initial Marks   18.000  45.998   17.999                                  46.000Measurement on Core.           18.219           17.792Unrolled7-3-74 8:54    1 min.   18.022                         46.041 18.027                                      46.048  8:58    5 min.   18.020                         46.035 18.023                                      46.048  9:08    15 min.  18.017                         46.028 18.020                                      46.036  9:23    30 min.  18.016                         46.026 18.018                                      46.030  9:53    1 hr.    18.014                         46.022 18.017                                      46.028  10:53   2 hr.    18.013                         46.022 18.015                                      46.023  1:53    5 hr.    18.010                         46.018 18.012                                      46.0197-8-74 11:53   123 hr.  18.002                         45.994 18.000                                      45.9907-16-74  8:53    312 hr.  18.006                         46.003 18.005                                      46.0047-22-74  8:53    456 hr.  18.001                         46.000 18.000                                      45.994______________________________________ 
    
     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.