WO1995027007A1

WO1995027007A1 - Resilient inlaid products and methods for making such products

Info

Publication number: WO1995027007A1
Application number: PCT/US1995/004149
Authority: WO
Inventors: Anthony N. Piacente; Donald R. Senior; George J. Papp
Original assignee: Congoleum Corporation
Priority date: 1994-04-05
Filing date: 1995-04-05
Publication date: 1995-10-12
Also published as: EP0754203A4; AU2278095A; JPH10511301A; CN1150443A; CA2186393A1; EP0754203A1; MX9604647A

Abstract

Disclosed are products and processes which utilize a reactive matrix (70) containing decorative elements to form the wear layer of a resilient, inlaid flooring product. The inlaid layer of the preferred floor covering products comprises an interpenetrating polymer network and a plurality of decorative elements at least partially embedded in the interpenetrating polymer network. The method aspects of the invention include consolidating the matrix (70) by exposure to elevated pressure and initiating polymerization of the reactive components in the matrix during the consolidation step.

Description

RESILIENT INLAID PRODUCTS AND
METHODS FOR MAKING SUCH PRODUCTS
Related APPlications
This application is a continuation-in-part of application
Serial No. 08/66,568, filed May 25, 1993, now pending.

Field of the Invention
The present invention relates to inlaid surface covering products and to methods of manufacturing such products. More particularly, the present invention relates to improved inlaid sheet materials useful as resilient surface coverings, including floor, wall and ceiling coverings; table, desk and countertop surfaces; automotive interiors; and the like.

Backqround of the Invention
Resilient inlaid sheet materials have wide applicability as surface coverings and are commonly used as the wear surface, or as a portion of the wear surface, in floor, wall and ceiling coverings. As used herein, the term "inlaid" refers to decorative sheet products characterized by a wear layer having certain decorative elements which remain visually unchanged as the covering wears.

Traditionally, resilient inlaid surface coverings include a wear surface comprising particles of resinous material, such as resinous chips, flakes, granules, beads or the like.

According to one known method of forming such products, a decorative inlaid pattern or design is built-up by applying particulate materials of different colors and/or shapes to a substrate or backing portion of the surface covering. Groups of stencils are commonly employed to arrange the particles in the desired pattern or design, and accordingly such constructions are sometimes referred to herein as "stencil build-up" type of inlaid products. In such products, the resinous particles are then consolidated under heat and pressure to form a wear layer in which the decoration is carried substantially through the entire thickness of the layer.

According to certain more recent construction techniques, the inlaid characteristic is achieved by forming a matrix comprising adhesive and resinous particulate material on the surface of a substrate. In such constructions, the matrix material is processed under appropriate pressure and temperature conditions to form a layer in which the decorative aspect provided by the resinous particulate is carried through the entire layer. These types of inlaid constructions, which are sometimes referred to herein as "matrix" constructions, are described, for example, in U.S. Patent No. 4,212,691 - Potosky et al.

While many variations of resilient inlaid surface coverings are known, among the most common type are matrix inlaid comprising thermoplastic particulate material bound together by a thermoplastic adhesive composition. It has heretofore been common practice to utilize a poly (vinyl chloride) ("PVC") plastisol composition as the thermoplastic adhesive composition in such inlaid floor coverings.

It is understood by those skilled in the art that inlaid types of floor covering products are different in many important respects from non-inlaid products. For example, the presence of decorative particulate material in the wear layer of inlaid flooring products is capable of producing aesthetic effects which are difficult, if not impossible, to produce in other types of flooring products. It is generally recognized that inlaid products can be manufactured to possess highly desirable three-dimensional effects and various textured appearances. Furthermore, inlaid floor coverings are frequently perceived by consumers and other users as having exceptional durability and high quality relative to non-inlaid materials. As a result of these and other properties, resilient inlaid floor covering products have generally enjoyed a significant degree of success in the floor covering industry.

Notwithstanding the successes of prior forms of resilient inlaid flooring, applicants have recognized that certain needs have remain unfulfilled by prior inlaid products. For example, the desirable appearance of most inlaid products is due in large part to the character of the decorative particles used, which particles are typically selected only after intensive study and analysis to suit the particular design objectives of the flooring manufacturer. However, the manufacturing techniques heretofore commonly used have sometimes resulted in, or at least tended to produce, a substantial degradation of the aesthetic properties being sought. More particularly, typical methods for the preparation of matrix type inlaid surface coverings involve introducing the decorative chips or flakes into a coating of thermoplastic plastisol adhesive on a substrate or backing surface, such as felt.

The particle-laden thermoplastic plastisol is then consolidated and fused by the application of heat and/or pressure from heated drums and/or planishing rolls. See, for example, U.S. Patent No. 4,212,691 - Potosky et al.

Applicants have recognized, however, that undesirable "streaking" of the decorative particles can sometimes occur as a result of the consolidation and/or fusion process. The term "streaking", as used herein, refers to the phenomenon wherein decorative particles, and decorative resinous particles in particular, tend to deform or elongate in the direction that the decorative sheet travels as it passes around the drum and/or through the planishing rolls. The desired aesthetic and/or textured appearance of the inlaid surface covering is therefore either impaired or not obtained.

Applicants have also recognized the need to improve the "hand" or feel of certain prior inlaid floor covering products.

As used herein, the term "hand" refers to the proper balance between the elongation and tensile strength of inlaid sheet materials. Prior inlaid products produced by the stencil build-up method are frequently deficient in that they are undesirably stiff, that is, the elongation value is too low.

This condition detrimentally increases the difficulty of installing such products, especially when such products are produced in wide-widths, for example 6' or greater. This characteristic makes the products concomitantly less desirable and less commercially successful.

On the other hand, inlaid products produced according to the adhesive matrix technique are frequently considered to be too limp, that is, the elongation value is too high. This condition is undesirable because "limp" floor covering products are frequently perceived by consumers as being of inferior quality.

Furthermore, applicants have recognized that certain commercial products made in accordance with the adhesive matrix technique have inferior indentation resistance, especially as compared to inlaid products made in accordance with the stencil build-up technique. As used herein, the term "indent resistance" refers to the ability of the surface coverings to resist indentation from repeated and/or prolonged application of pressure. Resistance to indentation is particularly important when the inlaid surface covering is used, for example, as a floor covering in a high traffic area that is subject to impact by heavy objects and/or exposure to concentrated loads resulting from objects such as tables, chairs and the like.

summary of the Invention
Applicants have discovered improved inlaid surface covering products and processes for producing such products.

The products and processes of the present invention overcome numerous deficiencies recognized by applicants in prior products and processes, including those deficiencies identified hereinbefore. More particularly, applicants have discovered that products and processes which utilize a reactive matrix containing decorative elements to form the wearlayer are capable of providing resilient inlaid floor covering products which have improved hand, especially as compared to stencil build-up products, and improved indentation resistance, especially as compared to inlaid products based on conventional adhesive matrix techniques.

The preferred floor covering products of the present invention are resilient inlaid floor covering products in which the inlaid layer thereof comprises an interpenetrating polymer network and a plurality of decorative elements at least partially embedded in said interpenetrating polymer network.

The method aspects of the present invention preferably include consolidating the matrix by exposure to elevated pressure and processing the particle-laden reactive matrix to form an inlaid wearlayer by at least initiating polymerization of the reactive components during consolidation of the matrix.

Applicants have found that such processing steps have a strong tendency to eliminate the streaking problem associated with prior methods.

The products and processes of the present invention also posses other advantageous features, as will become apparent from the detailed description hereinbelow.

Brief Description of the Drawings
Each of Figs. 1A, 1B, 1C, 1D and 1E is a diagrammatic, schematic drawing of one embodiment of the present invention, illustrating a preferred and typical process and apparatus therefor.

Detailed Description of Preferred Embodiments
I. THE PRODUCTS
The preferred surface covering products of the present invention comprise an inlaid wearlayer of matrix construction.

Importantly, the wearlayer of such preferred products comprises a plurality of decorative elements at least partially embedded in a composition comprising an interpenetrating polymer network.

A. Decorative Elements
As used herein, the term decorative element refers to an element of the wearlayer which carries or exhibits discrete decorative effects. In general, it is preferred that the decorative element comprise decorative particles, and even more preferably decorative resinous particles.

The decorative particles may comprise chips, flakes or granules prepared from resinous polymer compositions comprising synthetic resins, plasticizer4, fillers, light and heat stabilizers, dyes, colorants and pigments, and any other conventional desired or required constituents. One decorative resinous particle which may be preferred in ceratin embodiments are dry blended PVC resin particles of the type well known in the art.

According to embodiments in which the decorative elements comprise resinous flakes, the various constituents of the selected flake formulation are formed into sheets of the desired thickness by any suitable means, such as by passage through calendar rolls or by extrusion processes, and the resulting sheets so produced are converted into the desired geometric shapes, for example, squares, spheroids, triangles, circles, annuli, other polygons, and the like, or irregular sizes and shapes, or mixtures of any or all of such shapes. If a multiplicity of colors and hues are desired, then a multiplicity of separate sheets are so prepared, each with its own individual colorant, dye, or pigment, and then these sheets are individually cut into the desired sizes and shapes and then intermixed in the desired or required proportions in order to obtain the multi-colored effects.

Sheets of different thicknesses may be used also. The particulars of the particles used in such embodiments are fully disclosed in U.S. Patent No.

4,212,691 - Potosky et al., which is incorporated herein by reference.

The thickness of the various sheets of material from which the decorative chips or flakes are made depends primarily upon the desired pattern or design and upon the thickness of the layer of reactive adhesive into which they are to be ultimately embedded. Under normal circumstances, sheet thicknesses of from about 1 to about 3 times, and preferably from about 2 to about 3 times the thickness of the wet, tacky, ungelled reactive plastisol material are used. Such a thickness range is normally from about 5 mils to about 60 mils, and preferably from about 45 mils to about 55 mils. Naturally, various thicknesses of these geometric decorative chips or flakes may be intermixed.

The thickness of the layer of decorative chips or flakes, as initially applied to the surface of the wet, tacky, ungelled plastisol varies widely but normally is in the range of from about 3 mils to about 30 mils, or even more, as desired or required by circumstances and conditions.

The decorative chips or flakes need not necessarily be all plastic. A particularly desirable effect is obtained by using small pieces, chips or flakes of a metal foil, such as aluminum, which have been coated with a pigmented vinyl coating composition, similar to those described hereinbefore. These materials are sheeted, as described previously, and converted into geometric shapes, as desired. The metal foil can be extremely thin and can range down as low as about 2 mils, or even down to 0.6 mil. The metal foil can even be embossed to give it an additional luster. The longest or the largest dimension of these decorative chips or flakes may range up to as much as about 50 mils or 100 mils, or even to 500 mils in some circumstances.

B. The Interpenetratina Polvmer Network
Interpenetrating polymer networks (IPNs) are a special class of polymer blends in which two or more polymers exist in a highly networked structure. As the term is used herein, interpenetrating polymer network refers to true IPNs, apparent
IPNs, semi-IPNs, and combinations and hybrids of these.

A true IPN refers to those polymer networks in which the polymers in a system of two or more polymers are cross-linked to themselves but not to each other. In such a network, the distinct polymer systems form networks that interpenetrate each other. A semi-IPN refers to those polymer networks in which one polymer system exists in an uncross-linked state while a second polymer system is cross-linked to itself. The term apparent IPN refers to co-continuous interpenetrating phases in which none of the polymers is chemically cross-linked but which is nevertheless stabilized by physical polymer cross-links.

Although it is contemplated that the IPN of the present invention may be formed from polymeric materials of various types, it is generally preferred that the IPN comprise at least a first thermoplastic polymer interpenetrated with at least one thermoset polymer. As is generally known, thermoplastic polymers are generally not cross-linked polymers while thermoset polymers are generally at least partially crosslinked. In such preferred embodiments, therefore, the IPN comprises a semi-IPN and/or an apparent IPN.

Although it is contemplated that various techniques for forming an IPN may be adaptable for use in the present products, the preferred techniques are described in full detail hereinafter in connection with the method aspects of the present invention.

C. Thermoplastic Polvmer
A preferred thermoplastic polymer for use in the IPN portion of the inlaid layer of the present product is vinyl resin, and even more preferably poly(vinyl chloride) resin.

Although the preferred thermoplastic polymer comprises PVC homopolymer, many other vinyl resins may be used, for example, vinyl chloride-vinyl acetate copolymers, vinyl chloridevinylidene chloride copolymers, and copolymers of vinyl chloride with other vinyl esters, such as vinyl butyrate, vinyl propionate and alkyl substituted vinyl esters.

It is also preferred that the vinyl polymer comprise a plasticized vinyl polymer of the type well-known in the flooring industry. Conventional plasticizers may be used for this purpose, although it is generally preferred that secondary plasticizers be avoided. Suitable plasticizers include dibutyl sebacate, dioctyl sebacate, butyl benzyl sebacate, dibenzyl sebacate, dioctyl adipate, didecyl adipate, dibutyl phthalate, dicapryl phthalate, dioctyl phthalate, dibutoxyethyl phthalate, butyl benzyl phthalate, dibenzyl phthalate, di(2 ethylhexyl)phthalate, alkyl aryl modified phthalate esters, alkyl aryl hydrocarbons, tricresyl phosphate, octyl diphenyl phosphate, dipropylene glycol dibenzoate, and dibasic acid glycol esters.

D. Thermoses Polvmers
It is contemplated that numerous thermoset polymers may be used to form the preferred IPN in accordance with the present invention. Nevertheless, applicants have found that acrylic polymers produce highly desirable results. Preferably, the acrylic polymers of the present invention are formed from compositions comprising, and even more preferably consisting essentially of reactive acrylate compounds, and even more preferably reactive multifunctional acrylate compounds.

Exemplary and preferred reactive acrylates are reactive acrylate monomers and oligomers. The terms "acrylate monomer" and "acrylate oligomer" as used herein refer broadly to substantially low molecular weight compounds characterized by the presence of an acrylic acid or ester moiety (H2C=CHCO2R, wherein R is, for example, hydrogen or alkyl).

Particularly suitable acrylate monomers are multifunctional acrylate monomers, that is, monomers substituted with about two or more acrylic acid or ester groups. Such preferred compounds are referred to herein as acrylate monomers having a functionality of about 2 or greater.

In accordance with certain preferred aspects of the present invention the acrylate monomer comprises the reaction product of alcohol and acrylic acid reagent. The term "acrylic acid reagent" refers to acrylic acid and/or acrylic acid analogs which are reactive with alcohol. It is contemplated that the reaction of alcohol with acrylic acid reagent may comprise the reaction of one or more alcohols with one or more acrylic acid reagents. The term "alcohol", as used herein, refers to any organic compound which comprises one or more hydroxy substituents which are reactive with acrylic acid reagents. Accordingly, alcohols which may be reacted with acrylic acid reagents include mono-alcohols, diols, triols, and polyols, generally.

In accordance with certain preferred embodiments of the present invention, the monomer comprises the reaction product of diol and acrylic acid reagent. Preferred diols include ethylene glycol, propylene glycol, 1,6-hexahediol and neopentyl glycol. An example of a reaction product of diol and acrylic acid reagent which is particularly suitable for use in the plastisol composition 28 is 1,6-hexanediol dimethacrylate.

This material is commercially available from Sartomer Co. as
SARTOMER 239B.

In accordance with certain other preferred aspects of the present invention, the monomer comprises the reaction product of triol and acrylic acid reagent. Preferably, the triol comprises trimethylol propane. An example of a reaction product of triol and acrylic acid reagent for use in the plastisol composition 28 is trimethylol propane trimethacrylate. This material is commercially available form
Sartomer Co. as SARTOMER S-350.

Other suitable acrylate monomers would be readily apparent to one of ordinary skill in the art in view of the present disclosure.

E. Product properties
Although applicants do not intend to be necessarily bound by or limited to any particular theory of operation, it is believed that the formation of an interpenetrating polymer network containing substantially embedded decorative elements is in large part responsible for many of the beneficial properties and characteristics of the present invention. More particularly, the formation of an interpenetrating polymer network, particularly the preferred IPN's of the present invention, as an embedding material for the decorative elements contributes in large part to the avoidance of the undesirable streaking phenomena characterized by prior art processes.

For example, applicants believe that utilizing an IPN having a first polymer comprising thermoplastic resin and a second, thermoset polymer which interpenetrates with and into the thermoplastic polymer is responsible, in large part, for the excellent hand exhibited by the present products. More specifically, applicants have discovered that combining polymer components in the manner and under the conditions described herein permits an inlaid product having a balance of tensile strength and elongation that has heretofore been long sought but not achieved.

The products of the present invention preferably exhibit a rolling indentation resistance of no greater than about 5 mil, more preferably no greater than about 4 mil, and even more preferably no greater than about 3 mil. Rolling indentation resistance is one property that is an important measure of the quality of wearlayers used in floor and wall coverings in that it represent the ability of a wearlayer to resist permanent surface deformation resulting from movement of furniture, such as castered chairs and tables, along the surface. The results reported herein for rolling indentation resistance are determined by first establishing a path of travel, such as a circular path. Seven points along this path are then identified and the initial thickness of the sample is measured at each of these points.

An apparatus containing three casters with a 100 pound load per caster is run along the predetermined path such that each caster traverses the entire path one time.

The thickness of the product at the seven predetermined points after the casters have traversed the path is then measured.

This same test is then repeated for a second sample of the same product. The rolling indent resistance is then reported as the average value in mils (0.001 inch) obtained by subtracting the final thickness at each predetermined site and on each sample from the initial thickness at each site on each sample.

The products of the present invention also preferably exhibit a stiletto indentation resistance of no greater than about 10 mils, more preferably no greater than about 9 mils, and even more preferably no greater than about 8 mils.

Stiletto indentation resistance is a measure of the relative ability of a wear layer to withstand permanent deformation resulting from exposure to stiletto heels. The values reported herein for Stiletto indentation resistance are determined by exposing a sample of the product to an applied load of 150 pounds on a one-half inch diameter ball for a duration of about ten seconds. The test is conducted by providing a 2 i;h x 6 inch sample of the flooring product and marking on the sample three test points. The gauge of the flooring sample is measured at each test point using a Randall Stickney gauge equipped with a one-quarter inch flat foot. A 150 pound load is applied to each test point for ten seconds via a one-half steel inch ball.

The sample is allowed to recover from exposure to the load for a period of one hour, after which the depth of the residual indent at each test point is measured using a one-quarter inch hemispherical tip gauge. The final indentation thickness, measured in mils, is then subtracted from the initial thickness for each test point, and the average of these three readings is reported as the residual indentation resistance.

The preferred products of the present invention also possess an exceptional balance between tensile strength and elongation. More specifically, the present products preferably exhibit a relatively high tensile strength, which is indicative of the durability and quality aspects of the product, while simultaneously exhibiting relatively high elongation values, which are desirable from an installation point of view.

According to especially preferred embodiments, the present surface covering products exhibit a tensile strength of at least about 30 pounds, more preferably at least about 45 pounds, and even more preferably at least about 50 pounds. It is also preferred that the flooring products of the present invention possess an elongation of greater than about 25% and less that about 60%, and more preferably of from about 30% to about 60%, with a range of from about 45% to about 55% being even more preferred.

Tensile strength and elongation values reported herein are measured utilizing a Dilman tester, Model No. Motorized M1. A test sample of the flooring material measuring 1 inch x 1/32 inch x 5 inch, with the long dimension of the sample being parallel to the machine direction of the sample, is provided.

The flooring sample is then delaminated such that the overlying wear layer is separated from the substrate. The wear layer is then tested byplacing it in the tester with a one inch gap between the upper and lower jaws after calibration according to standard procedures. The apparatus is operated at a pull speed of about 12 inches per minute and otherwise according to standard procedures. The force, in pounds, at break is reported as the tensile strength. Elongation is similarly determined using standard procedures for such a Dilman tester, which provides an elongation value reported in inches. The value in inches is then multiplied by 100 and reported as elongation percent.

The products of the present invention also preferably exhibit a Taber stiffness value of no greater than about 600, more preferably no greater than about 500, and even more preferably no greater than about 450. The Taber stiffness values reported herein are determined using a Taber stiffness tester, Model 150-B or 150-D. The test utilizes a 2-3/4 inch x 1-1/2 inch test sample with the longer dimension parallel to the machine direction. Because temperature and humidity influence stiffness, samples are flattened for 24 hours with a six-pound weight in a constant condition room (730F +/- 20F, 50% RH +/- 4% RH). The weight is removed from the sample one hour prior to testing. The testing equipment is operated according to standard conditions with the degree switch set to 15 . The average of the "right" and the "left" readings is determined.

This result is multiplied, depending upon the pendulum weight, according to the following table to determine the resulting Tabor stiffness in half-Tabor stiffness units (TU/2).

Pendulum Weiqht Multiply Average Reading By:
None 0.5
125 0.62
250 1.25
500 2.5
1,000 5.0
2,000 10.0
II. THE PROCESSES
A. Providing the reactive matrix
In general, the present invention requires providing on a substrate a layer of reactive adhesive having decorative elements on or in the reactive adhesive layer. For the purposes of convenience, this layer is sometimes referred to herein as a particle-laden reactive matrix or reactive adhesive matrix. As the term is used herein, "reactive adhesive" refers to adhesive or binding compositions which include reactive components capable of reacting to form a polymer, copolymer, and/or polymer network.

According to highly preferred embodiments, the reactive adhesive comprises, and preferably consists essentially of, reactive plastisol, and even more preferably reactive PVC plastisol. As the term is used herein, "reactive plastisol" refers to a plastisol composition which includes reactive monomeric or oligomeric materials as described hereinbefore.

In general, it is preferred that the decorative elements are substantially embedded in the reactive adhesive material, it being recognized that in some embodiments at least some portion of the decorative element may not be in contact with the reactive adhesive. In certain preferred embodiments, for example, a portion of at least some of the decorative elements are exposed through the top of the wear layer and are therefore not in contact with the reactive adhesive. Nevertheless, for the purposes of the present invention, such decorative elements are considered to be substantially embedded in the matrix layer.

It is contemplated that numerous techniques are readily available within the scope of the present invention for providing a particle-laden reactive adhesive matrix layer on a substrate. For example, it is within the scope of the present invention that decorative elements may be simply admixed in a suitable blender or other mixing device with the reactive adhesive composition to produce a substantially homogeneous distribution of decorative elements n the reactive adhesive.

This reactive adhesive with the decorative elements distributed therein may be coated or otherwise applied to a suitable substrate using conventional coating equipment. However, the use of a reverse roll coater to apply a particle-laden plastisol composition is preferred in such embodiments. U.S.

Patent No. 5,178,912 - Piacente, which is assigned to the assignee of the present invention and incorporated herein by reference, discloses such techniques.

It is also within the scope of the present invention to provide such a particle-laden reactive layer by first coating the substrate with a layer of reactive adhesive and then depositing the decorative elements onto the surface of such reactive adhesive. Either as a result of decorative elements sinking into the reactive adhesive and/or as a result of a subsequent processing step, the decorative elements become substantially embedded in the layer of reactive adhesive. Such a process is described in more detail in connection with the attached Figures hereinafter.

The reactive adhesive of the present invention preferably comprises the following: thermoplastic polymer; plasticizer for the thermoplastic polymer; and a reactive component. The thermoplastic polymer and plasticizer are preferably selected in accordance with the teachings contained hereinbefore. In addition, the reactive components of the present invention preferably include not only the reactive monomeric and oligomeric compounds identified above, but also catalyst for the reactive compounds. In especially preferred embodiments, the thermoplastic polymer and the plasticizer together comprise a fluid, coatable poly(vinyl chloride) plastisol composition and the reactive component comprises reactive thermosetting monomer and catalyst for the monomer.

It is contemplated that a wide variety of catalysts would be suitable for use in the preferred reactive plastisol.

Preferably, the catalyst comprises a thermal catalyst which catalyzes polymerization and/or cross-linking of the reactive monomer upon exposure to elevated temperature conditions.

Applicants have discovered that certain catalysts are generally not preferred for use in accordance with the present invention while others are highly preferred. While not intending to bound by or limited to any particular theory of operation, it is believed that this dichotomy occurs because certain catalysts are deactivated by PVC resin. According to preferred embodiments discovered by applicants, therefore, the catalyst preferably comprises compounds characterized by the presence of a peroxide (-0-0-) moiety. It is contemplated that various types of peroxide catalysts may be used in the reactive plastisol compositions of the present invention, including alkyl peroxide, for example, di-t-butyl peroxide and dicumyl peroxide, and peroxy ester compounds.

As the term is used herein, a peroxy ester compound is a compound characterized by the presence of a -C(=O)-O-O- moiety, for example, t-butyl peroxybenzoate and t-butyl peroxy-2-methylbenzoate. The inventors have found that peroxy ester catalysts are preferred catalysts for use in the methods of the present invention t
Butylperoxy benzoate is particularly preferred and is commercially available as ESPEROX 10.

The catalyst is preferably incorporated in the reactive adhesive composition in an amount sufficient to initiate polymerization and/or crosslinking upon exposure of the plastisol to elevated temperatures and pressures, as explained more fully hereinafter.

Applicant's have found that the proportion the PVC resin to reactive components is of special importance in embodiments of the present invention which utilize reactive PVC plastisol as the reactive adhesive. More particularly, applicants have found that if the proportion of PVC resin to reactive acrylate is not within certain limits, then the unusual but highly desirable combination of physical properties according to the present invention will not be obtained. More particularly, applicants have found that the reactive plastisols of the present invention preferably have a PVC:reactive acrylate weight ratio of from about 2:1 to about 5:1, and even more preferably from about 3.5:1 to about 4.5:1.

The reactive PVC plastisol adhesive composition of the present invention preferably comprises from about 35 to about 50 parts by weight (pbw) of PVC resin, with from about 35 to about 45 pbw being even more preferred. The reactive plastisol also preferably comprises from about 8 to about 12 pbw of plasticizer, with from about 9 to about 11 pbw being even more preferred. The reactive plastisol also preferably comprises from about 8 to about 12 pbw of reactive acrylate, with from about 9 to about 11 pbw of reactive acrylate being even more preferred. Furthermore, from about 0.2 to about 0.5 pbw of catalyst is preferably incorporated in the reactive plastisol composition, with about 0.3 pbw being even more preferred.

For embodiments in which the reactive components of the reactive plastisol comprise multifunctional acrylate monomer and peroxy catalyst for the monomer, the reactive plastisol composition preferably comprises from about 35 to about 45 pbw of PVC resin, from about 8 to about 10 pbw of plasticizer for the PVC resin, from about 8 pbw to about 12 pbw of reactive monomer, and from about 0.2 to about 0.3 pbw of peroxy catalyst.

B. Consolidating the matrix
For embodiments in which the decorative elements are deposited onto a coating of reactive adhesive, the present methods preferably comprise consolidating the reactive matrix.

Although the decorative elements of the matrix may already be at least partially embedded in the reactive adhesive upon the formation thereof, as described above, it is preferred to consolidate and thereby compact and densify the matrix, preferably by exposing the matrix to pressure. Such a process serves to ensure maximum embedment of the particles and, importantly, to eliminate or at least substantially reduce unwanted voids in the adhesive matrix layer.

Accordingly, the consolidation procedure of the present invention preferably comprises exposing the reactive matrix to time, temperature and pressure conditions that are sufficient to cause substantial embedment of the particle in the adhesive matrix and to cause densification of matrix layer. Preferred conditions comprise exposing the reactive matrix layer to pressures of from about 150 to about 350 pounds (gauge) per square inch (psi). Such exposure may be provided by any one of several known means, including pressure drums and planisher rolls.

In certain preferred embodiments of the present invention, consolidation is carried out in two or more stages. Such a staged consolidation process is especially preferred for embodiments in which the decorative elements are deposited on a coating of reactive adhesive. More particularly, it is preferred in such embodiments that the reactive adhesive matrix is exposed to elevated pressures in a first consolidation step preferably by passing the substrate containing the particleladen adhesive matrix through a heated pressure drum which preferably exposes the matrix to pressures of from about 150 to about 300 psi. Such an operation serves not only to initiate consolidation of the matrix, but also to ensure sufficient embedment of the decorative elements into the adhesive. The adhesive matrix is then preferably exposed to higher pressures in subsequent stages of consolidation.

Subsequent stages of consolidation preferably comprise introducing the matrix into one or more planisher rolls, and preferably cooled planisher rolls. The product is preferably exposed to pressures of from about 330 psi to about 350 psi in such planisher rolls.

C. Gellina and fusion of the matrix
In the preferred multi-stage consolidation embodiments, the first stage of consolidation and gelation are carried out together in a heated pressure drum, as explained more fully hereinafter.

It is known that fluid PVC plastisol compositions comprise liquid plasticizer and a dispersion or suspension of PVC resin in the plasticizer. As is well known to those skilled in the art, the traditional, non-reactive fluid plastisol compositions previously used must be processed to develop the desirable wear resistant properties required for resilient flooring. The application of heat to non-reactive fluid plastisols generally causes physical changes in the rheology of the plastisol. That is, the fluid plastisol composition passes through or enters a gel phase as the temperature of the plastisol is raised to a sufficiently high level.

For the purposes of convenience, the term "gelation temperature range" is used herein to refer to the range of temperatures spanning from about the'pre-gelation stage of a plastisol, or about the initial increase in plastisol viscosity, to about the gel point. Techniques are well known and available to those skilled in the art for determining the gel point of any particular plastisol. For example, the gel point may be measured using a gelation plate which is heated only at one end, thereby developing a temperature gradient from one end of the plate to the other. When a fluid plastisol composition is cast onto the plate, the temperature of the plate at the point the plastisol loses its fluidity is frequently referred to as the plastisol's gelation temperature or gel point.

The gelation temperature range of any particular plastisol is a function of many variables, including the type and relative amounts of plasticizer resin present. It is generally contemplated, however, that the gelation temperature range of the fluid plastisols of the present invention will take place at temperatures of from about 1500F to about 3400F, and preferably from about 2800F to about 3400F. After complete gelation, the plastisol is generally a substantially dry, relatively firm solid.

It is generally preferred that the adhesive matrix of the present invention be gelled and fused. As is well known to those skilled in the art, the gel comprising the plasticizer and the PVC resin will fuse upon the application of sufficient heat thereto. In particular, it is known that the heating of a plastisol sufficiently past its gel point causes the plasticizer molecules to begin to become incorporated into the molecules of the PVC polymer, and "fusion" begins. As heating continues, the plasticizer becomes substantially integrated into the PVC polymer. In such a state, the plastisol is said to be a "fused-plastisol." The term "fusion temperature range" is used to refer to that temperature range over which fusion takes place, typically a range of temperatures beginning above about the gel point.

In many preferred embodiments, the fusion temperature range ic greater than about 2800F.

In certain embodiments of the present invention, the reactive particle-laden matrix may be both gelled and fused by simply elevating the temperature of the layer for a time sufficient to effect gelation and fusion. In such embodiments, fusion may be obtained by heating the consolidated product to a temperature of from about 3250F to about 4700F for a period of time of from about one minute to about six minutes.

Preferably, the product is heated to a temperature of at least about 3850F, depending upon the nature of the particular polymeric materials which are being used. This may be accomplished, for example, by passing the layer through a fusion oven.

It will be appreciated that the consolidation, gelation, and fusion steps described herein need not necessarily occur instantaneously and separately. Rather, it is preferred in ceratin embodiments that the steps of consolidation, gelation and fusion occur in stages, and that two or more of these steps may overlap with one or more of the other various steps. For example, it is preferred that both consolidation and gelation of the matrix are at least initiated by substantially simultaneously exposing the matrix to conditions of elevated pressure and temperature. This can be done using, for example, a heated pressure drum.

For embodiments in which the decorative elements are already distributed in the reactive adhesive at the time the adhesive is applied to the substrate, the application of pressure by the heated pressure drum is pyimarily for the purpose of smoothing the layer. On the other hand, for embodiments in which the decorative elements are deposited onto a coating of reactive adhesive, the pressures exerted by the heated pressure drum are relatively high, preferably from about 150 psi to about 300 psi, and are applied not only for smoothing, but also for the purpose of consolidation. In the latter case, gelation and consolidation are at least initiated substantially simultaneously.

Furthermore, it is contemplated that in certain embodiments fusion of the plasticizer and PVC resin may also begin to occur in the heated pressure drum. Thus, it is seen that the steps of consolidation, gelation and fusion may all take place to some degree in a single piece of equipment.

D. Polvmerization of the reactive matrix
Importantly and critically, the present methods require polymerizing the reactive components of the reactive matrix.

Furthermore, for embodiments in which the reactive matrix comprises substantially non-reactive polymer, such as PVC resin, and reactive components, it is highly preferred that themethods comprise at least partially polymerizing the reactive components in the presence of the non-reactive polymer to form an IPN. It is believed that such preferred processes serve to "lock" the decorative elements into the polymeric matrix and thereby contribute significantly to the advantages associated with the present invention.

According certain preferred embodiments, at least partial polymerization of the reactive compounds occurs prior to final consolidation of the wearlayer. Such a process may be accomplished, for example, by exposing the layer to consolidation pressure in two or more stages, with the earlier stage utilizing a lower pressure exposure than the later stage or stages. In this way, the inlaid layer is exposed to the highest consolidation pressure only after the advantageous properties of the present invention are at least partially imparted by at least partial polymerization of the reactive compounds.

As is understood by those skilled in the art, prior plastisol compositions containing decorative elements require exposing the matrix layer to consolidation under heat and pressure. As mentioned hereinbefore, it was during this process that streaking and elongation of the decorative elements sometimes occurred. Applicants have found, however, that this undesirable phenomena is substantially avoided by the preferred processes of the present invention which require that the reactive components of the reactive adhesive undergo at least partial polymerization during the consolidation step.

Such preferred processes serve to at least initiate formation of an IPN so that the pressures normally experienced by the adhesive matrix layer during consolidation do not elongate or deform the decorative elements.

According to highly preferred embodiments, applicants have found that it is critically important that the reactive components of the reactive plastisol be selected to at least initiate polymerization prior to exposing the reactive matrix to the maximum pressure experienced by the matrix during the consolidation step. For the preferred multi-stage consolidation step of the present invention, it is preferred that polymerization at least be initiated prior to the final stage of consolidation, and even more preferably that polymerization be initiated during the initial stage of consolidation.

Applicants have also found that it is preferred to at least initiate polymerization of the reactive components of the reactive matrix prior to full fusion of the PVC resin in the plastisol, and even more preferably prior to substantial initiation of fusion.

Initiation of polymerization in accordance with the present invention is desirably achieved by exposing the particle-laden reactive matrix to processing in a heated pressure drum, as described in further detail hereinafter in connection with the Figures.

III. DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
A preferred embodiment of the present invention will now be described below in connection with the attached Figures.

With specific reference to Fig. 1A of the drawings, there is shown therein a rotatable supply roll 10 from which is delivered a relatively flat, fibrous or non-fibrous backing sheet material or substrate 12, such as a fibrous, felted or matted relatively flat sheet of overlapping, intersecting fibers, usually asbestos or of cellulosic origin. The substrate 12 may, if desired, be a woven, non-woven, knitted or otherwise fabricated textile material, paper stock, a sheet or film of a synthetic or man-made plastic or any of the materials disclosed, for example, in U.S. Patent Nos. 3,152,002; 3,232,780; 3,239,364; 3,359,352; and 3,660,187.

A base resinous polymer composition 14, which is preferably a polyvinyl chloride (PVC) plastisol, is substantially uniformly applied to the surface of the substrate 12 at a coating station 16, for example, by means of a reverse roll coater.

The thickness of the base resinous polymer composition or plastisol 14, as it is applied to the surface of the substrate 12 and is still wet, is substantially uniform and is in the range of from about 0.005 inch to about 0.060 inch, or even thicker, if so desired or required by future requirements or needs.

The particular means for applying the base resinous polymer composition 14 to the surface of the substrate 12 does not relate to the essence of the present invention and substantially any suitable coating means may be employed.

Although the preferred synthetic resin for the base resinous polymer composition 14 is a PVC homopolymer, many other vinyl resins as described hereinbefore may be used.

In addition to plastisols, organosols and aqueous lattices, for example, aquasols and hydrasols, may be used, employing as the dispersing or suspending media organic solvents and water, respectively.

Other constituents of the base resinous polymer composition 14 may include blowing or foaming agents, such as azodicarbonamide, if a blowing or foaming procedure is desired; various accelerators/stabilizers, initiators and catalysts, for example, zinc octoate and lead phosphite; various heat andtor light stabilizers, for example, metallic soaps; W absorbers; colorants, dyes and pigments, including titanium dioxide; solvents and diluents, for example, methyl ethyl ketone, methyl isobutyl ketone and dodecyl benzene; fillers, for example, clay and limestone; viscosity modifiers; antioxidants; and bacteriostats and bacteriocides.

After the base resinous polymer composition 14 has been applied and adhered to the substrate 12, it is then heated in an oven or other suitable heating apparatus 18 maintained at an elevated temperature of from about 2400F to about 4500F, and preferable from about 2600F to about 4100F for a period of time of from about one minute to about five minutes, whereby the composition gels and becomes firm. The temperature and the time are interdependent and the higher the temperature, the shorter the time and vice versa. The elevated temperature, however, is not so high as to activate or to decompose any blowing or foaming agent which may be present in the formulation of the base resinous polymer composition 14 as to cause blowing or foaming at this time.

Optionally, the gelled or firmed base resinous polymer composition 14a may then be printed or coated, if so desired, at a printing station 2s by means of two or more pairs of suitably engraved printing rolls 22 and 24 with printing ink compositions containing dyes, colorants, pigments, and the like, if a design or pattern is desired or required in the final product. The printing ink composition may also contain synthetic resins, plasticizers, stabilizers, antioxidants, and blowing or foaming modifying agents in selected areas if an embossed or textured surface appearance is desired or required.

Drying of the applied printing ink composition is accomplished by air drying, or by the use of conventional heating and drying procedures.

In certain embodiments, the blowing or foaming action of the potentially foamable base resinous polymer composition 14 may be of such a strong or vigorous nature that the gases which are developed or released by the blowing or foaming agent tend to escape upwardly from the heated base resinous polymer composition and tend to enter any wear layer or any other layer lying above it to undesirably affect the smoothness and evenness of the wear layer surface. This could be ruinous to the smoothness and evenness of surfaces, if such characteristics are desired, and could be undesirable from an aesthetic viewpoint.

Such undesirable effects may be avoided by placing a relatively thin barrier coat or layer having a thickness of only about 6 mils or less, down to about 1 or 2 mils, on top of the base resinous polymer composition 14, either before or after any printed pattern or design is applied thereto but before any further coatings or layers are applied. Such a barrier coat or film effectively prevents the gases from escaping upwardly from the blowing or foaming base resinous polymer composition.

Such a barrier coat is applicable as a film but is normally applied as a plastisol or resinous polymer composition in a thin layer of a resin, such as a vinyl chloride polymer or copolymer having a relatively high molecular weight. Gelling of such a barrier coat naturally follows at an elevated temperature below the activation or decomposition temperature of the blowing or foaming agent. A typical barrier coating station 25 is generally indicated in Fig. 1A of the drawings.

Two typical barrier coat formulations are as follows.

Parts* Parts*
Polyvinyl chloride, high mol. wt.,
dispersion grade, inherent
viscosity 1.4 89 90
Polyvinyl chloride, high mol. wt.,
blending resin, inherent
viscosity 0.9 11 10
Dioctyl phthalate 6
Epoxidized soya oil 5 5 2,2,4-trimethyl-1,3-pentanediol
diisobutyrate 6.9 8.8
Butyl benzyl phthalate 29 19.6
Polydodecyl benzene 8.5 5.5
Ba-Zn phosphite stabilizer if.25 3 Wabsorber 0.32 0.32
Toner 0.01 0.01
*Parts by weight, based on 100 parts of resin. phr
As shown in Fig. 1B of the drawings, the gelled resinous polymer composition 14b is then advanced to a coating station 26 where a reactive plastisol 28, which is a wet, tacky, ungelled plastisol, is substantially uniformly applied to its surface, for example, by a suitable coating applicator roll 30 dipping into a conventional coating par 32.

The thickness of the layer of wet, tacky, ungelled plastisol 28 as it is applied to the surface of the base resinous polymer composition 14b and is still wet is substantially uniform and is in the range of from about 20 mils to about 26 mils. The thickness of the coating of the layer of ungelled plastisol 28 may be controlled by an air knife doctor device 34 and a backing roll 36. The particular means for applying and controlling the thickness of the layer of ungelled, reactive plastisol 28 does not relate to the essence of the present invention and substantially any suitable coating device may be employed, provided it is capable of accurately applying and controlling the thickness of the coating.

The layer of reactive adhesive composition 28 which is, of course, ungelled, uncured and unfused, has a viscosity in the range of from about 2500 centipoises (cps) (Brookfield) up to as high as 3500 cps (Brookfield No. 3 spindle, 20 rpm, 87-890F) provided the plastisol retains its wet, tacky properties and characteristics.

As will be seen subsequently, the thickness of the layer of wet, tacky, ungelled plastisol 28 and its viscosity are among the factors which will determine the metering and the control of the amount and the thickness of the layer of decorative chips or flakes which are deposited and adhered thereon.

As shown in Fig. 1C of the drawings, the gelled resinous polymer composition 14b and the layer of ungelled resinous polymer composition 28 thereon are then forwarded to a decorative chip or flake coating device 36. The resinous polymer composition 14b and the layer of ungelled resinous polymer composition 28 passes over a rotatable index roll 38 and then under a supply hopper 40 containing chips, flakes or granules 42 which are to be substantially uniformly deposited on the surface of the layer of wet, tacky, ungelled plastisol 28 for subsequent adhering and embedding therein.

The preferred equipment for supplying the particles 42 to the reactive adhesive does not form a part of the present invention and is fully disclosed in U.S. Patent No. 4,212,691.

As the layer of adhesive plastisol composition 28 passes forwardly underneath the flexible seal blade member 54, a portion of the supply bank of decorative chips or flakes 42 is deposited substantially uniformly thereon and is adhered thereto. Preferably, the decorative chips or flakes are deposited onto the plastisol composition 28 in chip:adhesive weight ratio of from about 1.5:1 to about 2.0:1. More preferably, a weight ratio of about 1.8:1 is used.

Substantially simultaneously or immediately after deposition of the decorative chips or flakes, the substrate carrier 12 carrying the gelled resinous polymer composition 14b and the layer of wet, tacky, ungelled plastisol resinous polymer composition 28 thereon come into sliding contact with the angularly inclined bed plate 46 and is guided forwardly and upwardly in positive fashion thereby.

A rotating back beater 56 which is provided with radiallyextending spokes or veins is supplied just beyond the upper end of the angularly inclined bed plate 46 and intermittently strikes the back surface of the carrier substrate 12 whereby it is shaken or vibrated so that any partially, insufficiently or loosely adhered decorative chips or flakes 42 which have not previously slid or fallen backwardly and downwardly into the supply bank are given an additional chance to be released to slide back into the supply bank, whereby only well-adhered decorative chips and flakes remain on the surface of the layer of wet, tacky, ungelled plastisol 28.

The substrate 12 carrying the gel led base resinous polymer composition 14b and the layer of wet, tacky, ungelled plastisol resinous polymer composition 28 thereon with the adhered decorative chip or flake materials thereon then passes onward and upwardly over a rotatable guide roll 58 to be forwarded for further processing and finishing, including consolidation, gelation and fusion, as discussed more fully hereinafter.

Such further processing and finishing operations may take many different forms and may involve many different forms of apparatus. One such further processing procedure is illustrated in Fig. 1D, wherein there is shown the first stage of a multi-stage consolidation procedure employing a large steam-heated (or superheated steam-heated) rotatable cylindrical drum which is capable of being heated to elevated temperatures of about 4000F, or even higher, to initiate consolidation. In general, it is preferred that exposure of the adhesive matrix to such a heated drum raises the temperature thereof to about 300-3100F. This is also a gelation stage and the first stage of a multi-stage polymerization.

Located around the cylindrical surface of the heated drum are a plurality of heated, rotatable pressure-applying cylindrical press rolls 62, 64, 66 and 68 which are capable of applying pressure to any materials placed on the cylindrical surface of the heated cylindrical drum 60. Pressures of up to about 300 psi of contact between the heated cylindrical drum 60 and the individual press rolls 62, 64, 66 and 68 may be used.

Applicants have found that it is highly preferred for the adhesive matrix layer on product 70 to be exposed to relatively low pressures, and preferably pressures of no greater than about 200 psi, upon initial contact with the heated drum 60.

As a result, polymerization of the reactive components of the matrix is initiated while the matrix is exposed to relatively low consolidation pressures. This may be achieved, for example, by applying relatively low pressures, for example 150200 psi, to press rolls 62 and 64 while applying higher pressures, for example from about 250 to about 300 psi, to press rolls 66 and 68. In this way, the first consolidation stage is itself a multi-stage process insofar as different stages of pressure are utilized. Because the preferred dwell time of the adhesive matrix around the heated drum 60 is about 20 to about 60 seconds, this permits a period of about 10 to about 30 seconds for initiation of polymerization under conditions of relatively low pressure consolidation.

Thus, the substrate 12 containing the base composition 14b and the plastisol composition 28 is exposed to temperature and pressure conditions from the heated drum 60 and the press rolls 62, 64, 66 and 68 for a time effective to substantially simultaneously (1) at least initiate polymerization of the reactive components of the reactive plastisol and (2) at least initiate consolidation and gelation of the particle-laden plastisol layer. According to preferred embodiments, the drum 60 heats the adhesive matrix to a temperature of from about 295 F to about 3150F, with a temperature of from about 3000F to about 3100F being even more preferred. In highly preferred embodiments, the cylindrical drum 60 produces a matrix temperature of about 3050F.

Applicants have found that such preferred procedures result in at least the initial conversion of the reactive plastisol into an IPN. That is, heating and/or pressurizing the particle-laden reactive layer as described herein produces polymerization, and preferably cross-linking, of the reactive compounds in the presence of the PVC resin and the decorative elements, which in turn at least begins the formation of the preferred interpenetrating polymer network.

It will be appreciated, however, that further reaction of the reactive components may preferably occur in subsequent processing steps, such as fusion of the wearlayer. In these embodiments, the IPN becomes more highly networked and the full advantage of the present is realized.

Exposing the matrix to the elevated temperatures of drum 60 not only preferably initiates polymerization of the reactive components, but also causes at least partial gelation, and even more preferably substantially full gelation, of the plastisol.

During the preferred initiation of polymerization and gelation, the present processes also preferably comprise initiating consolidation of the adhesive matrix layer. This initial consolidation stage is achieved primarily through the plurality of heated, rotatable press rolls 62, 64, 66 and 68.

During this initial consolidation stage, the decorative surface covering is preferably exposed to pressures of from about 150 to about 300 psi, with the pressures increasing as the product 70 travels around the periphery of the drum.

Preferably, the decorative surface covering is exposed to a pressure of no greater than about 300 psi in the first stage of consolidation.

The time required for the ungelled, coated substrate to be partially cured and consolidated by passing between the drum 60 and the press rolls 62, 64, 66 and 68 may be selected as desired and is a function, among other parameters, of the nature and thickness of the resinous compositions and the temperatures and pressures used. Preferably, the ungelled substrate is exposed to the above noted preferred elevated temperatures and pressures for a period of time of from about 20 seconds to about 40 seconds, with a period of time of from about 25 seconds to 35 seconds being preferred. Preferably, the pre-gelled, coated substrate is subjected to such elevated temperatures and pressures for a period of time of about 30 seconds to cause partial polymerization, partial consolidation and substantially complete gelation.

As one of the results of this consolidation stage, a partially consolidated resinous polymer sheet material 70 is obtained, wherein the decorative chips or flakes 42 are embedded into wet, tacky, ungelled plastisol 28 and form a particle laden plastisol having a relatively firm, smooth surface tightly bonded to the base layer resinous polymer composition 14 situated on the underlying carrier substrate 12.

The gelled, partially consolidated, partially polymerized matrix 70 is then preferably processed so as to complete consolidation, if that is required or desired, and to complete fusion. It is contemplated that complete fusion of the plastisol may occur as a result of simply exposing sheet 70 to elevated temperatures in a fusion oven of a type common in the flooring industry (not shown). In such embodiments, it is preferred that the reactive plastisol matrix is substantially fully fused and the reactive components thereof are substantially fully polymerized. Fusion in such cases is normally obtained by heating the product 70 to a temperature of from about 3250F to about 4700F for a period of time of from about one minute to about six minutes.

Preferably, the product 70 is heated to a temperature of at least about 3850F, depending upon the nature of the particular polymeric materials which are being used. Such elevated temperatures are also normally sufficient to bring about blowing and foaming in the base resinous polymer composition, if a blowing or foaming agent was originally included in the base formulation. Blowing or foaming may take place in any and all areas wherein the effect of the blowing or foaming agent has not been inhibited by the inclusion of an inhibitor in certain areas of the selected portions of the desired printed pattern or design applied by the printing ink compositions.

In more preferred embodiments, however, consolidation, polymerization and fusion is completed in a stage-wise process as illustrated in Fig. 1E. In accordance with such a process, the gelled, partially consolidated, partially polymerized product 70 is introduced to an oven comprising a series of infrared heating banks, shown schematically in Fig. 1E as 80.

This step thus preferably further elevates the temperature of the adhesive matrix layer to about 3700F and causes further polymerization of the reactive components. Preferably, fusion of the plastisol into the PVC resin is also at least initiated by introduction of the product 70 into the oven 80.

The partially fused product 70 which exits oven 80 is then introduced to planisher rolls 81 wherein the adhesive matrix layer of product 70 is exposed to a second stage of consolidation. It is preferred that during the second stage of consolidation the adhesive matrix layer is exposed to pressures of from about 320 to about 350 psi, and even more preferably of from about 330 to about 350 psi. It is also preferred that the planisher rolls 81 are cooled planisher rolls.

The product which leaves planisher rolls 81 is then introduced into a gas fired radiant oven 82 wherein the adhesive matrix is preferably substantially completely fused and polymerized. Accordingly to preferred embodiments, this final fusion and polymerization stage comprises heating the adhesive matrix to a temperature range of from about 270 to about 3200F for time sufficient to effect substantially complete fusion and polymerization. Applicants have found that such times are preferably from about 1 to about 4 minutes.

Optionally but preferably, the product 70 exiting oven 82 is exposed to yet a second set of planisher rolls 83. While planisher rolls 83 serve, in part, to further consolidate the adhesive matrix layer of product 70, it is preferred that such planisher rolls also comprise embossing rolls which emboss the surface of the product 70 in a desired pattern or design.

In planisher rolls 83, the adhesive matrix layer is also preferably exposed to pressures of from about 320-350 psi, and even more preferably of from about 330-350 psi.

The final product is then advanced to a rotatable wind-up roll 84 for disposition or for further processing nd handling, as desired or required.

The present invention will be further described with particular reference to the following examples which are primarily illustrative of the present invention.

EXAMPLE I
The apparatus schematically and diagrammatically illustrated in Fig. 1 is used to carry out the following process:
The fibrous backing sheet material or substrate comprises a relatively flat, 0.040 inch thick fibrous sheet of felted and matted asbestos fibers provided with an acrylic smooth leveling coating thereon.

The base resinous, potentially foamable polymer composition, such as PVC plastisol, is applied to the substrate to a substantially uniform wet thickness. Gelling and firming of the potentially foamable base resinous polymer composition takes place in a heated oven at an elevated temperature of about 3000F for a period of time of about three minutes. The gelled, firmed PVC plastisol is then printed with a pattern or design, if desired, after which a barrier coat layer is applied to a thickness of about 3 mils on the surface of the PVC base layer.

The printed, gelled and firmed base layer plastisol having a barrier coat layer thereon is then coated with a layer of a wet, tacky, ungelled PVC plastisol resinous polymer composition containing: about 33% by weight of calcium carbonate filler; about 9% by weight butyl benzyl phthalate plasticizer; about 40% by weight of PVC homopolymer resin; and about 10% by weight
SARTOMER 350. The PVC homopolymer resin is a low-medium molecular weight resin comprising a mixture of 80% by weight of dispersion resin and 20% by weight of suspension resin. The dispersion resin is sold by Occidental Chemical Co. under the trade designation 688C and the suspension resin is sold by
Borden under the trade designation R501. The reactive plastisol further contains 3% by weight, based on. the weight of
SARTOMER 350, of ESPEROX 10.

The gelled base resinous polymer composition with the layer of ungelled, wet, tacky plastisol thereon is then advanced to a chip or flake coating station, whereat there is deposited substantially uniformly thereon a layer of resinous decorative chips or flakes in a chip:adhesive weight ratio of about 1.8:1. The coated substrate is then forwarded to a consolidation apparatus, such as shown in Fig. lD, for at least partial polymerization and/or consolidation.

The main, superheated steam-heated rotating drum has a temperature of about 4100F and the four peripheral rotatable pressure applying rolls 62, 64, 66 and 68 apply pressures of 150, 200, 250 and 300 psi, respectively. The dwell time of the product in the drum is about 30 seconds.

During the partial consolidation/polymerization procedure, the decorative chips or flakes are compressed into and become embedded in the layer of wet, tacky, ungelled plastisol.

Partial polymerization of the SARTOMER 350 and partial consolidat on of the particle laden plastisol occurs substantially simultaneously during the consolidation/ polymerization procedure.

The partially consolidated product is then advanced to a series of heaters and planisher rolls, as shown in Fig. 1E, to produce a resilient inlaid floor covering product.

COMPARATIVE EXAMPLE I
This example is directed to inlaid surface coverings typical of prior art products which do not utilize a reactive plastisol adhesive. An inlaid surface covering is prepared using the procedure, components and apparatus described in
Example I, except the plastisol adhesive consists essentially of about 13% by weight of calcium carbonate filler, about 26% by weight plasticizer and about 51% by weight PVC resin.

COMPARATIVE EXAMPLE II
An inlaid surface covering is prepared using the procedure, components and apparatus described in Example I, except the plastisol adhesive consists essentially of about 40% by weight of calcium carbonate filler; about 16% by weight plasticizer; and about 32% by weight PVC resin.

The products produced in accordance with each of the above
Examples are tested to determine the following properties: tensile strength; elongation; indent resistance (residual and rolling); delamination; and Taber stiffness. These results are reported in Table 1 below. The results for Comparative Example
I and Comparative Example II are identified in the Table by the designations CEX.I and CEX.II, respectively. Also reported in
Table 1 are test results for a leading competitive inlaid product, namely CORLON, produced using the stencil build-up technique. (COLONS is a registered trademark of Armstrong
World Industries, Inc.)
TABLE 1
150 Lbs.

Taber
Elonga- Rolling Stiletto Delamination Stiffness
Gauge Tensile tion Indent (lgr/72Hrs) (6000 cycles) (50F/73F)
Sample (mils} (Lbs) (%} (rills) (mils) (PassFail) (TU/2)
EX.I 84-86 59-62 45-55 3.4 9.3/8.9 Passed 500/420
CEX.I 85-87 23-25 130-140 6.5 12.0/11.5 Failed 215/185
CEX.II 84-86 17-20 100-110 5.6 11.4/11.0 Failed 245/205
CORLONs 82-84 54-56 20-30 3.3 8.3/7.8 Passed 800/675
The above test results demonstrate that the inlaid surface coverings of the present invention possess highly desirable physical properties, as measured by tensile strength, elongation, indent resistance, delamination and stiffness.

In comparison to typical prior products which do not utilize a reactive matrix, (CEX.I and CEX.II), the surface coverings of the invention possess superior tensile, elongation, indent and delamination properties. In addition, the present inlaid surface coverings possess superior hand as compared to the prior art surface coverings which are either excessively flexible (CEX.I and CEX.II) or excessively stiff (CORLONe).

Claims

We claim: 1. A process for manufacturing a decorative inlaid floor covering product comprising: (a) providing substrate meons for supporting overlying layers of the product at least during the manufacture thereof; (b) providing a reactive plastisol layer on said substrate, said reactive plastisol layer comprising reactive plastisol and a plurality of discrete, decorative elements at least substantially embedded in said reactive plastisol, said reactive plastisol comprising vinyl resin, plasticizer for said vinyl resin, and a reactive component; (c) gelling said plastisol; (d) during said gelation step (c), at least partially polymerizing said reactive component; and (e) forming a wear resistant inlaid layer by substantially fully fusing said reactive plastisol.

2. The process of claim 1 wherein said step of providing a reactive plastisol layer comprises providing a coating of said reactive plastisol on said substrate and depositing said decorative elements onto said coating.

3. The process of claim 1 wherein said decorative elements comprise decorative resinous particles.

4. The process of claim 1 wherein said reactive component comprises monomer capable of polymerizing to a thermoset polymer and wherein the weight ratio of said vinyl resin to said reactive component is from about 2:1 to about 5:1.

5. The process of claim 1 wherein said step of providing a reactive plastisol layer comprises providing a coating of said reactive plastisol on said substrate, depositing said decorative elements onto said coating, and substantially embedding said decorative elements into said plastisol coating.

6. The process of claim 1 wherein said plastisol comprises from about 35 to about 50 pbw of vinyl resin, from about 8 to about 12 pbw of plasticizer, and from about 8 to about 12 pbw of reactive monomer.

7. The process of claim 7 wherein said plastisol further comprises from about 0.2 to about 0.5 pbw of catalyst for catalyzing polymerization of said monomer.

8. The process of claim 1 wherein said step of at least partially polymerizing comprises heating said reactive plastisol to temperatures of from about 200 to about 3000F.

9. The process of claim 8 wherein said partial polymerization comprises exposing said adhesive matrix to a rotating heated drum for a period of from about 20 to about 40 seconds.

10. The process of claim 1 wherein said vinyl resin comprises poly(vinyl chloride) resin.

11. In a process for manufacturing a decorative floor covering of the type having an inlaid wearlayer comprising the steps of providing substrate means for supporting the wear layer at least during the manufacture thereof, providing the substrate with a layer of fluid plastisol composition, depositing decorative resin particles onto said layer of fluid plastisol composition to produce a particle-laden fluid plastisol layer, and fusing the particle laden plastisol layer and thereby forming an inlaid wearlayer for the floor covering, the improvement characterized by the steps comprising:

: (a) forming the plastisol to comprise from about 35 to about 50 pbw of vinyl resin, from about 8 to about 12 pbw of plasticizer, from about 8 to about 12 pbw of reactive acrylate monomer, and from about 0.2 to about 0.5 catalyst for catalyzing polymerization of said monomer to produce a particle-laden reactive plastisol layer; and (b) exposing said particle-laden reactive plastisol to time, temperature and pressure conditions effective to substantially simultaneously (i) cause at least partial polymerization of said reactive monomer and (ii) cause at least partial gelation of the particle-laden plastisol layer; and (c) forming a wear resistant inlaid layer by fully fusing said particle-laden reactive plastisol and polymerizing said reactive acrylate monomer.

12. The process of Claim 11 comprising forming the plastisol to comprise from about 35 to about 45 pbw vinyl resin.

13. The process of Claim 12 comprising forming the plastisol to comprise about 41 pbw vinyl resin.

14. The process of Claim 11 wherein said vinyl resin comprises poly(vinyl chloride) resin.

15. The process of Claim 11 comprising forming the plastisol to comprise from about 9 to about 11 pbw plasticizer.

16. The process of Claim 15 comprising forming the plastisol to comprise about 12 pbw plasticizer.

17. The process of Claim 11 wherein said plasticizer comprises butyl benzyl phthalate.

18. The process of Claim 11 comprising forming the plastisol to comprise from about 9 to about 11 pbw of reactive acrylate monomer.

19. The process of Claim 18 comprising forming the plastisol to comprise about 10 pbw of reactive acrylate monomer.

20. The process of Claim 11 wherein said monomer comprises 1,6-hexanediol dimethacrylate.

21. The process of Claim 11 wherein said monomer comprises trimethylolpropane trimethacrylate.

22. The process of Claim 11 wherein said catalyst comprises peroxy ester catalyst.

23. The process of Claim 22 wherein said catalyst comprises t-butyl peroxybenzoate.

24. A resilient inlaid floor covering comprising an inlaid layer comprising an interpenetrating polymer network and a plurality of decorative elements at least partially embedded in said interpenetrating polymer network.

25. The inlaid floor covering of claim 24 wherein said interpenetrating polymer network comprises at least a first thermoplastic polymer and at least one thermoset polymer.

26. The inlaid floor covering of claim 25 wherein said floor covering has a rolling indentation resistance of no greater than about 5 mils.

27. The inlaid floor covering of claim 25 wherein said floor covering has a stiletto indentation resistance of no greater than about 10 mils.

28. The inlaid floor covering of claim 25 wherein said floor covering has a tensile strength of at least about 30 pounds and an elongation of greater than about 25% and less than about 60%.

29. The floor covering of claim 25 wherein said floor covering has a rolling indentation resistance of no greater than about 5 mils, a stiletto indentation resistance of no greater than about 10 mils, a tensile strength of at least about 30 pounds, and an elongation of from about 25% to about 60%.

30. The inlaid floor covering of claim 25 wherein said floor covering has a Taber stiffness of no greater than about 600.

31. The inlaid floor covering of claim 25 wherein said thermoplastic polymer comprises poly(vinyl chloride).

32. The inlaid floor covering of claim 31 wherein said poly(vinyl chloride) comprises plasticized poly(vinyl chloride).

33. The inlaid floor covering of claim 25 wherein said thermoset polymer comprises acrylic polymer.