GB2053734A - Process for the manufacture of a floor covering - Google Patents

Abstract

In a process for the manufacture of a decorative flooring material based on a fusible resin, the material is planished prior to application of a near layer and fusion to form the final product. Planishing, by a steel roll, removes air from the material and increases penetration of the inks used in the decorative pattern, while providing a final product with irregular texture.

Description

SPECIFICATION A process for forming a floor covering This invention is directed to a process for forming a floor covering.

The present invention provides a process for making a floor covering having a base layer formed from a layer of finely divided fusible resinous materials bound together to form a resinous layer having an irregular surface which comprises: (a) printing with a geliable, fusible printing ink on the surface of the layer to provide it with a decorative pattern, and then gelling the ink, (b) planishing the printed surface, (c) applying a fusible wear layer plastisol to the planished printed surface, and (d) heating to fuse the printing ink, base layer material, and the wear layer coating.

More especially, there is provided a process for making such a floor covering wherein planishing is carried out with a smooth surface steel roll and the wear layer plastisol is advantageously applied by means of a reverse roll coater.

Advantageously, the planishing step is carried out using a smooth surface chilled chrome steel roll in conjunction with a rubber backup roll to provide a nip size which is approximately half that of the thickness of the base layer, and the layer being planished is wrapped around a portion of the smooth surface steel roll.

This portion advantageously extends around an arc of the roll surface subtending an angle up to 160".

The planishing step smoothes the printed surface of the base layer and consolidates the base material, removing trapped air. Surprisingly, however, the fused product has an irregular surface texture.

More especially, the invention is directed to a process for making a floor covering material wherein a base material is formed from a layer of finely divided resinous materials, the particles of which are bound together to form a layer having an irregular surface. The upper, irregular surface of this layer is printed with a gellable ink to provide a design on it. The ink is gelled after printing. Then the printed surface is planished with a steel roll having a smooth surface. Over the planished surface is then provided a wear layer plastisol which is applied by means of a reverse roll coater. Finally, the composite structure is heated and the heating operation fuses the printing ink, the base material and the wear layer coating so as to provide a floor covering material.Surprisingly, the material has an irregular surface texture and it has been found that the process provides a reduction of the blistering which often occurs in the printed areas of products made by an otherwise similar process but in which the planishing is omitted.

One method of carrying out the process of the invention will now be described in greater detail, by way of example only, with reference to the accompanying drawing, which is a schematic diagram of one form of apparatus suitable for carrying out the process.

Referring to the drawing, a web 20 of a base layer comprising finely divided fusible resin particles bound together, on a carrier, which may be a permanent carrier or may be separable from the base layer after completion of the manufacturing process, is passed in the direction indicated by the arrow A past a printing station, indicated generally by the reference numeral 1, and subsequently heated by gas or electrical resistance heaters 2 and, optionally, 3, which gel the ink. A planisher, indicated generally by the reference numeral 4, and which comprises a steel roll 5 and a rubber backup roll 6, is so positioned in the path of travel of the web that the web carrying the gelled ink passes over up to about 160" of the surface of the steel roll 5.

The web 20 now passes to an optional pre-wetting station 11, and then to a coating station, indicated generally by the reference numeral 7, which is a reverse roll coater comprising an upper coating roll 8, rotating in the direction shown by the arrow B so that the portion of its circumferential surface in contact with the web 20 is moving in the direction contrary thereto, and a backup roll 9. A wear layer composition is applied by the coating roll 8. Finally, the coated web passes through a heating station comprising an oven 19 to fuse the resins of the base, the ink and the wear layer coating.

In a presently preferred process, the floor covering is made with a base layer of a sintered layer of fine vinyl polymer particles. The surface of the sintered particles is a sandpaper-like surface. It is quite easy to print a design into this surface since the printing ink can readily be applied to an irregular surface. A wear layer coating is then placed over the printed surface, and this wear layer is normally about 10 mils (0.25 mm) thick. The irregular surface makes it difficult to use a reverse coaterto apply a continuous smooth coating on the surface and, consequently, the irregularities in the surface have, prior to the present invention, been filled in with a clear plastisol by a pre-wettechnique. This provides a relatively smooth surface, and a reverse roll coater can be used to provide the wear layer.It has been found that sometimes blisters occur in the vicinity of the printing ink, apparently because the printing ink has not properly penetrated into the sintered base (dry blend). Often the ink has not penetrated to the base of the dry blend and air may be trapped at the base of the dry blend below the ink. This trapped air may cause blistering. The planishing of the present invention causes slight consolidation of the base layer and the gelled ink squeezes out the trapped air.

Through the use of a planishing operation, it has been found that not only can the pre-wetting step prior to the reverse roll coating application of the wear layer be eliminated, there is also a substantial reduction of blistering and the unexpected result that the end product is provided with an "orange peel" or rough surface texture which often lends a realistic appearance to the printed design.

In the preferred process, a base layer is formed from a conventional dry blend mix which is a mass of vinyl resin particles in a fine resinous mass. A particular dry blend that may be utilized is: Ingredients Parts by Weight Exxon 9290 (PVC Homopolymer MW-83, 900) 250 M-275 (Organotin Stabilizer) 5 DOP (Di-2-ethylhexyl phthalate) 75 Hi Sil 233 (Amorphous hydrated silica) 0.63 The dry blend is applied to a carrier, separate from or part of, to a 28 mil (0.71 mm) thickness, and it is applied as a wet plastisol coat. The dry blend material is then sintered at 350 F (177" C).

Plastisol inks which are advantageouslyfoamable, are printed onto the sintered dry blend in the desired design (pattern). The inks are gelled at 270"F (121"C). Atypical ink that can be utilized is: Ingredients Parts by Weight Exxon 605 (PVC Homopolymer Dispersion Resin MW-80,400) 2000 DOP (Di-2-ethylhexyl phthalate) 900 Drapex 4.4 (Octyl Epoxy Tallate) 40 ABC-1 8 (Organic Zinc Complex) 60 3000 Referring again to the drawing, the printing operation is carried out by any conventional type printing structure, for example a ZimmerTM printer which is a flatbed printer or by a conventional rotary screen printer. The appropriate heating is carried out by the heaters 2 which gel the printed ink.At this point, the sheet may receive supplemental heating through the use of the heater 3 which brings the temperature of the face of the sheet up to 300 F (about 1 50"C) just prior to the time that it enters the planisher structure 4 composed of a steel roll 5 and a rubber backup roll 6. The rubber backup roll has a rubber hardness of 70 Shore A. The nip setting between the steel roll and the backup roll is .013 inches (0.33 mm). The steel roll is a chrome-coated roll which is internally chilled with cold water and operates with a surface temperature of about 150"F (about 65"C). It is possible to wrap the sheet material around approximately 1600 of the circumference of the chrome roll, and this will help in cooling the surface of the sheet down to about 200"F (about 93 C).

After planishing, the sheet has a fairly smooth surface. The gauge of the sheet or thickness thereof is approximately 4 to 7 mils (0.1 to 0.18 mm) less than the sintered gauge of the base layer. The sheet then passes on to the reverse roll coater 7 which has an upper roll 8 and a backup roll 9. The reverse roll coater is conventional in the art and it applies a clear plastisol wear layer coating to a thickness of 10 mils (0.25 mm).

The wear layer coating wiil have the following formulation: Ingredients Parts by Weight Exxon 6337 (PVC Homopolymer Dispersion Resin MW-141000) 550 Blacar 1738 (PVC Homopolymer Dispersion Resin MW-233000) 1360 Blacar 501 (PVC Homopolymer Blending Resin MW-95300) 816 DOP (Di-2-ethylhexyl phthalate) 550 TXIB (2-2-4-Trimethyl-1,3 Pentanediol Monoisobutyrate Ester) 408 S-160 (Butyl phthalate) 217 Synpron 744 (Ba. Zn. Phosphite Stabilizer) 81.6 The composite product now moves to the oven 10 where it is heated to 385 F (196"C) to fuse the resins of the plastisol coating, the material of the ink and the resins of the sintered dry blend base.

As indicated, minor variations can be made in the process. The heating step carried out by the heater 3 could be eliminated should the surface of the sheet be at a sufficient temperature for planishing after it leaves oven 2. Also it is possible that a pre-wet step 11 could be provided to provide a very smooth surface sheet prior to the time that the reverse roll coating operation is carried out. This pre-wet step would require the application of a plastisol coating the same as that provided by the reverse roll coater. However, this coating is applied with a conventional forward roll coater, and smoothed with a doctor blade.

In carrying out the prior art process which involved the forming of a sintered sheet and the printing and coating thereof without planishing, there was formed an end product which had a very smooth surface in the region of the printed inks. Unexpectedly, as a result of the planishing operation, the surface texture of the finished product produced by the process of the invention has, in the areas of the printed design, an "orange peel" or rough surface even though the sheet was planished or smoothed. Consequently, although the planishing provides a relatively smooth surface to secure a uniform continuous application of the wear surface, it also unexpectedly causes the end product to have a desirable irregular surface in the printed areas after the fusing of the sheet.

Claims (7)

1. A process for making a floor covering having a base layer formed from a layer of finely divided fusible resinous material bound together to form a resinous layer having an irregular surface which comprises: (a) printing with a gellable, fusible printing ink on the surface of the layer to provide it with a decorative pattern, and then gelling the ink, (b) planishing the printed surface, (c) applying a fusible wear layer plastisol to the planished printed surface, and (d) heating to fuse the printing ink, base layer material, and the wear layer coating.

2. A process as claimed in claim 1, wherein planishing is carried out with a smooth surface steel roll.

3. A process as claimed in claim 1 or claim 2, wherein the plastisol is applied by means of a reverse roll coater.

4. A process as claimed in'any one of claims 1 to 3, wherein the planishing step is carried out using a smooth surface chilled chrome steel roll in conjunction with a rubber backup roll to provide a nip size which is approximately half that of the thickness of the base layer prior to its passage through the nip, the layer being planished being wrapped around a portion of the smooth surface steel roll.

5. A process as claimed in claim 4, wherein the layer extends around an arc of the roll surface subtending an angle upto 160"C.

6. A process as claimed in claim 1, carried out substantially as described with reference to and as illustrated by the accompanying drawing.

7. Afloor covering, whenever made by a process as claimed in any one of claims 1 to 6.