IE50219B1 - Process for sealing fiber web of open structure and structure and product resulting therefrom - Google Patents

Abstract

Fibre web of open structure is coated with a layer of heat curable, mechanically frothed, flexible thermoplastic vinyl polymer foam. The web is then heated to between the fusion temperature and the decomposition temperature of the polymer to fuse and collapse the foam. The resulting product is a suitable substrate for decorative sheet type covering material.

Description

This invention relates to decorative sheet-type covering material and especially to a method for preparing suitable substrate for such material by sealing a fiber mat or web of open structure.

Decorative, flexible sheet-type covering materials such as 5 wall or floor coverings are well known. Frequently, such coverings involve the use of a chemically blown foamable plastic applied in a liquid state to a substrate. This foamable liquid is then gelled, frequently printed with a design, and expanded by heat to e.g. three times its original thickness. Conventional use of such chemically foamed material is described for instance in U.S. Patents Nos. 3,458,337 and 3,293,094.

While the use of chemically foamed plastic over substrates in the production of sheet covering materials is well-known and has been extensively practiced, the resulting products have not always been entirely satisfactory. Where porous substrates or irregular substrates have been used, results have been less than satisfactory since penetration of the foamable liquid coating into the supporting substrate frequently results in magnified surface distortions in the finished product. This is especially noticeable where printed patterns are formed on the foamed layer or are printed onto an unfoamed layer prior to foaming of the layer. 50218 The use of non-foamable material for sealing and coating a porous or irregular substrate has been generally unsatisfactory due to penetration of the coating material into the openings in the porous substrate.

In addition to chemically foamed plastics 5 of the type mentioned above, mechanically foamed plastics in which air or other gas is introduced into the plastic as by heating or other forms of mechanical aeration are well known, as exemplified for instance in U.S. Patent No. 3,511,788. Such mechanically foamed plastics have been suggested for a variety of purposes such as in very thin layers for application to a variety of substrates as suggested in the abovementioned Patent No. 3,511,788. Such foams have also been utilized as backing for sheet covering materials, especially flooring to provide resiliency under foot.

It is also quite common in the flooring industry to make an embossed foam product either by use of chemical means such as suppresent inks, etc., in the manner taught by the above-mentioned U.S.Patents or by mechanical embossing of the foamed layer or completed product. Mechanical embossing is a well known technique as exemplified for instance by the more detailed descriptions in U.S.

Patents Nos. 3,345,234, 3,748,151 and 3,887,678.

Summary of the Invention It is an object of the present invention to provide a process for making substrate for decorative, flexible sheet-type covering material. The process of the invention comprises: 50218 a) coating at least one side of a flexible porous mat with a layer between 10 and 150 mils (0.25 and 3.8 mm) thick of heat curable mechanically frothed, flexible, foamed thermoplastic vinyl polymer; and b) then heating the layer of foamed polymer to a temperature between the fusion temperature and the decomposition temperature of the polymer to thereby cause the foam to thermally collapse into a continuous fused film; wherein said mat has openings between 1 and mils (0.025 and 0.5 mm) in the smallest linear dimension with at least 50% of such openings having smallest linear dimensions between 2 and 10 mils (0.05 and 0.25 mm).

Preferably the foam as applied to the mat has a viscosity between 3000 and 25,000 cp. Preferably, the layer at step (a) above is at least 20 mils (0.5 mm) thick.

Product of the invention is decorative, flexible, sheet-type covering material comprising of a flexible, porous mat having adhered to at least one face thereof a layer between 2 and 50 mils (0.05 and 1.3 mm) thick of thermally collapsed and fused mechanically frothed, flexible, foamed thermoplastic vinyl polymer wherein: a) the crushed layer has a continuous, non-porous surface conforming to the general contour of the porous mat; and b) the openings in the porous mat are between 1 and 20 mils (0.025 and 0.5 mm) in the smallest linear dimension with at least 50% of such openings having smallest linear dimensions between and 10 mils (0.05 and 0.25 ran). 50218 Detailed description While the invention is applicable to porous mats made from any flexible material, the preferred material is glass fibers in woven and non-woven form with non-woven glass fiber mats being £> especially preferred.

The mats to which the invention is applicable are those which are sufficiently porous so that ordinary plastisol or organosol sealing materials penetrate the openings of the mat, thereby making it difficult or impossible to obtain a smooth coating of plastic on the mat. Mats suitable for use in the present invention are those in which the openings in the mat are between 1 and 20 mils (0.025 and 0.5 mm) in the smallest linear dimension with at least 50% of such openings having smallest linear dimensions between 2 and 10 mils. Preferred mats include those having a thickness between 10 and 40 mils and a density between 0.5. and 4 lbs. per 100 square feet. Such mats may be manufactured by conventional techniques used for manufacturing non-woven glass mats with the glass fibers used preferably having an average diameter between 5 and 20 microns, more preferably between 7 and 15 microns, and fiber lengths between 0.2 and 1.5 inch (5 and 38 mm). Binders conventionally used for coating glass fibers may be used and where used are normally present in amounts between 1 and 50 wt% of the mat. Suitable binders for coating glass fibers of the mats used in the invention include, for instance, ureaformaldehyde latexes, thermosetting resins such as polyester resins, epoxy resins and the like and may include, among other conventional binders, those mentioned in U.S.

Patent No. 3,554,851 to Modigliani.

The binder may, of course, be applied to the glass fibers in the conventional manner.

As mentioned, the foam used in forming product of the invention by the process of the invention comprises themoplastic Ξ vinyl polymer with vipyl chloride polymers and copolymers being especially preferred. Vinyl polymers suitable for use in the invention include a wide variety of vinyl materials such as those described in the above-mentioned U.S. Patent 3,511,788 as well as those conventional polyvinyl chloride (PVC) materials known in the art for use in chemically foamed materials, including for instance those described in the above-mentioned U.S. Patents 3,458,337 and 3,293,094. Similar vinyl polymers in latex form are also suitable. Mechanically foamed PVC plastisols and organosols are the preferred materials for the thermally collapsed layer of the product of the invention.

The mechanically frothed and thermally collapsed foam layer of the product of the invention provides smoother surfaces on porous substrates than the previously used chemically foamed plastics and less porous surfaces than mechanically foamed plastics applied and cured without collapsing. Thermally collapsed foam layers of the invention are also more suitable for this purpose than the relatively low density crushed foams which are conventionally used as backing for draperies and upholstery fabrics in the textile industry. 50218 As mentioned the present invention relates to flexible sheettype covering material suitable for covering walls and floors.

In order to achieve the necessary flexibility in the finished product it is necessary that the substrate as well as the collapsed foam layer and other optional layers of the invention be flexible rather than rigid. Plastic materials are considered sufficiently flexible for this purpose when, in the form of a foamed and cured unreinforced i inch (6.3 ran) foam sheet, they can be bent 180° around a 1 inch (25.4 mm) mandrel without permanent set.

Such materials are generally known to those skilled in the flooring and textile industries as are the various types of substrates and other materials which are suitable for use in making flexible decorative wall or floor covering materials.

While flexible porous mats of the invention having a layer of mechanically frothed and thermally collapsed heat cured flexible plastic foam thereon may for some purposes be suitable as substrates for sheet-type covering material without further treatment, it is in many cases desirable to apply to the crushed foam layer a conventional sealing coat of suitable material such as PVC plastisol or organosol. In accordance with a particularly preferred embodiment of the invention, the layer of mechanically frothed and thermally collapsed flexible plastic foam is further covered with a conventional layer of foamed plastic such as foamed PVC plastisol or organosol.

This provides desired resiliency to the finished product. It will be understood that additional foamed or unfoamed layers of conventional materials for use in flooring, e.g. PVC plastisols or organosols as well as layers of printing or other decorative effects may be also used, all in a conventional manner. Conventional vinyl wear layers for optional use on products of the invention may, for instance, comprise any of the PVC resin materials normally used in connection with the manufacture of sheet vinyl flooring and may specifically include but are not limited to those described in the above-mentioned U.S. Patent No. 3,458,337. Where used, such vinyl wear layers are typically on the order of between 5 and 25 mils (0.13 and 0.63 mm) thick for flooring materials and may be opaque, translucent or transparent as desired. Other layers of sealer, pigmented layers, plastisols, wear layers, etc., known in the art may also be used.

PVC plastisol or organosol used in forming the optional foamed layer of the product of the invention described above may be any of the conventional PVC materials known in the art for use as foamed layers on flooring materials and include for instance those described in the above-mentioned Patents, 3,458,337 and 3,293,094.

The foaming or blowing agent incorporated in the optional foamable plastisol may also be a conventional flowing agent or catalystactivated blowing agent such as are well known in the art fpr producing foamed plastisols or organosols. Suitable blowing agents include, for instance, azodicarbonamide (ABFA) and other conventional blowing agents such as those enumerated in the above-mentioned U.S. Patent No. 3,293,094.

While a wide variety of thermoplastic vinyl foam materials are suitable for use in the mechanically frothed and thermally collapsed 8QS18 heat cured foamed thermoplastic layer of the invention, selection of a particular plastics for a given application preferably takes into account such factors as the nature of the porous mat to be coated, the desired viscosity of the foam material as applied to the mat, the viscosity of the foamed plastics as applied, the particle size of PVC resin, degree of solvation of the plastisol, etc.

While the viscosity of foamed thermoplastics utilised in making products of the invention by the process of the invention may vary widely depending upon the type of mat and coating and collapsing conditions used, preferred viscosity of the foam as applied to the mat is between 3,000 and 25,000 centipoises (cp) as measured on a Brookfield RVF viscosimeter with a TA T-bar spindle at 4 RPM.

While coating of the flexible porous mat with mechanically foamed plastics in accordance with the invention is frequently carried out at room temperature, this is by no means critical and coating temperatures between about 50° and 150°F. are suitable with many of the commonly used plastics.

Coating of the mechanically frothed foamed plastics onto the porous substrate in accordance with the invention may be accomplished by any suitable means such as, knife coating or extrusion, after the porous mat is coated with mechanically foamed plastics in accordance with the invention, the foamed plastics is heated to thermally collapse the foam into a continuous fused (cured) film. This is accomplished by suly'ecting the foamed plastics to a temperature between the fusion temperature and the decomposition temperature of the particular plastics involved. For best results the temperature used for thus thermally collapsing the plastic foam will be in the range of from 20°F (11°C) above the fusion temperature of the plastics to20°F (11°C) below the decomposition temperature of the plastics. Suitable temperatures for thermally collapsing foam in accordance with the invention will of course vary widely depending upon the melt temperature and decomposition temperature of the particular plastics used,but for the preferred polyvinyl chloride plastisols and organosols will frequently range between 375°F (190°C) and 425°F (220°C). Likewise, exposure times may vary considerably but will frequently range between 1 and 5 minutes to achieve complete collapsing and fusing of the foamed material.

The primary objective of the process of the invention is to produce a product wherein the porous mat is sealed with a plastic coating which would be difficult to apply by other means. The process of the invention is especially useful in sealing porous mats with plastisols and organosols which in the unfoamed condition would normally penetrate the mat excessively due to their relatively low viscosity. By applying such materials in the form of mechanically frothed foams, the significantly higher viscosity of the foamed material is utilized to prevent excessive penetration of the coating material into the mat. It will be appreciated that while the coating of the present invention does not penetrate the porous web or mat excessively, some limited penetration is normal and desirable so that the continuous plastic film resulting from the process of the invention is partially embedded in the fiber matrix. As the foam collapses due to heating as required by the process of the 80219 invention, the resulting continuous, non-porous plastics film assumes the general contour of the surface of the open fiber web being coated. Relatively smoother surfaces may be obtained by coating the web with relatively thicker layers of plastics. In applications where a smooth, level substrate surface is required, it is therefore frequently desirable to apply to the surface formed by the process of the invention a conventional base coat, prime coat or smooth coat. Any conventional smooth coat such as that described in U.S. Patent No. 3,519,469 may be used for this purpose.

The following example is intended to illustrate a preferred embodiment of the invention without limiting the scope of the invention.

Example A simulated floor covering material of the invention was prepared by applying approximately 20 mils (0.5 mm) of mechanically frothed PVC organosol foam to one face of a non-woven fibreglass o mat approximately 18 mils (0.46 mm) thick and weighing 1.1 lb/100 ft 2 (54 g.m ). The foam as coated onto the mat had a density of 0.7 g/cc and a viscosity of 9000 cp. The composition of the organosol was as follows: Parts by Weight PVC-polyvinyl acetate copolymer resin 40 PVC homopolymer suspension resin 60 plasticizer 75 Kerosine Diluent 7 Stabilizer 1.0 Limestone Filler 40 Silicone Surfactant 4 After application of the foamed organosol to the mat, the foam coated mat was heated for three minutes in an oven operated at 370°F (187°C) in a first zone and 350°F (176°C) in a second zone. The foam collapsed completely in the oven and the organosol cured as a continuous fused film partially embedded in the fiber matrix. The thus sealed mat was then smooth coated as described in U.S. Patent No. 3,549,469, by coating with non-foamable PVC organosol, passing the coated sheet through the compression nip between a back-up roll and a steel drum operating at 320°F (160°C) and gelling the organosol in a short wrap on the steel drum beyond the nip.

After smooth coating, chemically foamable PVC organosol was coated onto the gelled foamable organosol in the same amount and the sheet was heated for two and a half minutes in the 370-350°F (187-176°C) oven. The decorative printed layer normally included in such constructions was omitted; however, the sample sheet was identical to conventional rotogravure cushion sheet vinyl floor covering in all other respects. This sheet was free of blisters, craters and pinholes and had the smooth, even surface normally desired in the floor covering material.

The glass mat used in this example was made up of glass 5 fibers having an average diameter of about 9 microns and an average length of about 0.75 inch (19 mm). The fibers were coated with urea-formaldehyde binder with the binder making up about 15 wt% of the mat. The openings in the porous mat had smallest linear dimensions averaging about 5 mils (0.013 mm) with almost all of such openings having smallest linear dimensions between 2 and 10 mils (0.05 and 0.25 mm).

While the invention has been described with respect to certain embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications may be made.

Claims (13)

1. Process for making substrate suitable for decorative, flexible sheet type covering material comprising the steps of:a) coating at least one side of a flexible porous mat with a layer between 10 and 150 mils (0.25 and 3.8 mm) thick of heat curable mechanically frothed, flexible, foamed thermoplastic vinyl polymer; and b) then heating the layer of foamed polymer to a temperature between the fusion temperature and the decomposition temperature of the polymer to thereby cause the foam to thermally collapse into a continuous fused film; wherein said mat has openings between 1 and 20 mils (0.025 and 0.5 mm) in the smallest linear dimension with at least 50% of such openings having smallest linear dimensions between 2 and 10 mils (0.05 and 0.25 mm).

2. Process according to claim 1 wherein the foam as applied to the mat has a viscosity between 3000 and 25,000 cp.

3. Process according to claim 1 or claim 2 wherein the coating applied at step (a) of claim 1 is a layer at least 20 mils (0.5 mm) thick.

4. Process according to any one of claims 1 to 3 wherein the porous mat is a non-woven mat of glass fibers having average diameters between 5 and 20 microns and average lengths between 0.2 and 1.5 inch (5 and 38 mm) and the mat is between 10 and 40 mils (0.25 and 1.2 mm) thick and has a density between 0.5 and 50218 4 lb/100 ft 2 { 24.5 and 196 g.m -2 ).

5. Process according to any one of claims 1 to 4 wherein the temperature to which the layer of foamed polymer is heated to collapse the foam is in the range of from 20°F (11°C) above the 5 fusion temperature of the polymer to 20°F (11°C) below the decomposition temperature of the polymer.

6. Process according to any one of claims 1 to 4 wherein the foamed vinyl polymer is polyvinyl chloride plastisol or organosol.

7. Product produced according to the process of any one of the 10 preceding claims.

8. Decorative, flexible, sheet-type covering material comprising a flexible, porous mat having adhered to at least one face thereof a layer between 2 and 50 mils (0,05 and 1.3 mm) thick of thermally collapsed and fused, mechanically, frothed, flexible, foamed 15 thermoplastic vinyl polymer wherein: a) the crushed layer has a continuous, non-porous surface conforming to the general contour of the porous mat; and b) the openings in the porous mat are between 1 and 20 mils (0.025 and 0.5 mm) in the smallest linear dimension 20 with at least about 50% of such openings having smallest linear dimensions between 2 and 10 mils (0.05 and 0.25 mm).

9. Covering material according to claim 7 wherein the porous mat is a non-woven mat of glass fibers having average diameters between 5 and 20 microns and average lengths between 0.2 and 1.5 inch (5 and 38 mm) and wherein the mat is between 10 and 40 mils (0.25 and 1.2 mm) thick and has a density between 0.5 and 4 lbs. per 100 ft 2 (24.5 and 196 g.m -2 ).

10. Covering material according to claim 8 or claim 9 further including a layer of foamed plastics material adhered to the layer of crushed thermoplastic and a decorative pattern applied to the surface of the foamed plastics layer.

11. Covering material according to any one of claims 8 to 10 wherein the vinyl polymer comprises cured polyvinyl chloride plastisol or organosol.

12. Process for making substrate substantially as herein described with reference to the Example.

13. Decorative flexible sheet type covering material incorporating a substrate substantially as herein described with reference to the Example. Dated this 7th day of May 1980, /TOMKINS & CO., [Applicants' Agents,