CA1164505A - Reversible floor covering structure and method of manufacture - Google Patents

Abstract

Abstract of the Disclosure A unitarily-molded, flexible, reversible floor covering including a decorative side having decorative alternating patterns of at least one of different colored polymeric materials different colored fibrous materials, different levels of polymeric materials, different levels of fibrous materials or polymeric materials and fibrous materials and a utility side having a plurality of debris-retaining depressions formed in a polymeric mater. A
method of molding the floor covering structure in an essentially single step is also described.

Description

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URh Backxround of the Invention _ The invention relates to a floor covering structure and method of manufacture. In a more specific aspect, the present invention relates to an automotive mat structure and method of manuEactllre.
A wide variety of floor covering structures, such as automotive mats, have heretofore been proposed. Generally, such floor coverings fall into -two main categories. First, the upper surface of the covering is primarily designed for decorative purposes with the utilitarian functions thereof being secondary. Such coverings include primarily carpeting of a wide variety of patterns, colors, etc. including multi-colored, mul-ti-leveled and other forms.
The second category includes coverings of polymeric materials whose primary ~unction is utilitarian with secondary decorative features. This latter category thus includes polymeric materials having depressions ~ormed therein to receive and retain debris such as mud, water, dirt, etc. In both cases, however, the bottom of the covering serves only to function as a substrate for the upper portion or as a non-slip surface to prevent the covering from sliding on the surface on which it is laid. While the latter types of Eloor covering can be reversed so that the friction-reducing side faces upwardly and the covering can thus be said to be reversible, it is quite apparent that the thus exposed upper surface is not designed and will not function adequately as the utilitarian sur~ace for a number of reasons. In many cases the side designed to be the bottom surface lacks structural strength and wear properties which prevent its use as a traffic-bearing surface. In those instances in which the back is formed of a polymeric material capable of withstanding wear and in most cases having a multi-level structure to serve a skid-resistant function, the structure itself is incapable of withstanding traffic, is incapable of serving as a traf-ic surface since it is not sufficiently flat to serve as a walking surface and in all instances any depressions formed therein are insuficient in depth and/or lateral dimension to serve as debris-rPceiving and retaining ~`' .

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depressions. In any event such prior art floor coverings are neither designed nor adapted to be truely reversible in nature and particularly to include a decorative side and Q utility side, both of which can function as traffic-b~aring surfaces.
In light oE the above it would therefore be highly desirable to provide a reversible floor covering material incorporating all of the ad-vantageous features, which have been previously described as existing in different types of mats, in a single unitary floor covering structure.
In addition to failing to provide truly reversible Eloor covering structures such as mats and the like, the prior art also leaves much to be desired in the manufacture of such structures. The problems of forming floor coverings such as mats and the like are non-existent where a single polymeric material is utilized. Obviously, in such a case an essentially single step molding operation will suffice. Likewise, ~here backing of a polymeric material is applied to the back of a carpeting, the polymeric material may be simply spread or calendered onto the back of the carpet and heat set or cured.
~lowever, where a pluralîty of diEferent materials are to make up the carpeting material or a molding operation is necessary and desirable~ present day procedures become unduly cumbersome, time consuming, and/or expensive. In addition where heat and/or pressure are utilized in the formation of the floor covering, the severity of the conditions limit the materials which may be utilized in many instances and in other instances result in a product lacking flexibility or other desirable properties.
It would therefore also be highly desirable to provide a process for manufacturin~ a floor covering or the like which is capable of producing the floor covering structure in an essentially single molding operation, is capable of combining a plurality of components having differing ph~sical characteristics and properties in a single unitary structure, which will permit the utilization of heat and/or pressure sensitive materials and which will produce a product having desirab:Le features of flexibility and the like.

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Summary of the Invent-ion In accordance with the present invention there is provided a unitarily molded, $1exible, reversible $100r covering structure such as a mat, which has a decorative side having decorative alternating patterns of at least one o~ different polymeric materials, diEferent colored fibrous materials, different levels of polymeric materials, different levels of fibrous materials or polymeric materials and fibrous materials and a utility side having a plurality of debris-retaining depressions formed in a polymeric material. In addition a novel method of forming such a mat or floor covering is provided comprising an essentially single step technique.
The novel floor covering structures of ~he present invention are particularly useful as mats and particularly as automotive mats. The floor covering is completely reversible in that one side constitutes a utility side which can be used under adverse and high tra:Efic conditions and an opposite decorative side which is esthetically attractive and can be utilized under normal conditions ~nd normal tra$fic.
The utility side of the floor covering comprises a polymeric material having an optimum balance of resistance to abrasion, heat, ultra-violet light, etc. This side can be decorative to the extent that it is either solid colored or multi-colored but its main function is to serve as a traffic surface in adverse weather or the like For the latter purpose 9 the utility side has a plurality or pattern of depressions adapted to receive and retain water, dirt, dust and/or mud. For this purpose, the depressions must have su$$icient depth and be sufficiently large in lateral dimension. In addition, the bottoms of the depressions are preferably imperforate so as -to prevent dust, dirt and water from passing through the mat thereby depositing debris on the floor underneath or causing dirt to adhere to the decorative side.
The raised portions of the utility side are sufficient to provide structural reinforcement ~or the floor covering while at the same time providing abrasion resistance without interferring with maneuverability of the $eet thereo~. A cushioning e~fec-t also is provided by such raised portions.

~ 3 The decorative side of the floor covering or mat can be formed of a polymerlc material, a fibrous material or a combination of both. In any event, decorative al~ernating pa-tterns of at least one of different colored thermoplastic materials, different colored fibrous materials, different levels of polymeric materials, different levels of fibrous materials or combinations of thermoplastic materials and fibrous materials are provided. For example, the surface can be carpe-ting of a single level of multiple colors or patterns, a sculptured effect or a decorative effect achieved by crushing the fibers in a separate heat treatment or preferably during -the molding operation, stitching of pa-tterns into the pile of the carpet or melting a pattern or patterns of a polymeric material into or onto the fibrous pile of a carpeting or any combination of these. In any event, the backing, adhesive or fused side of a carpeting or the like forms a substrate between ~the utility side and the decorative side.
The floor covering structures of the present invention have ad~itional advantages, irrespective oE which side is utilized, as a traffic bearing surface in that, when the utility sicle is utilized as the traffic surface, friction between the fibrous materials of the decorative side and the floor will prevent slipping while, when the decorative side i~ used as a traffic bearing surface, the pattern of depressions on the utility side will serve to prevent slipping on the floor beneath. The reversibili-ty of the floor covering structure also increases the service life thereof.
The polymeric materials utilized for the utility side of the floor covering or for the design features of the decorative side may be a polyvinyl chloride material, including conventional polyvinyl chlorides or plastisols, vulcanizable rubber ma-terials, such as styrene/butadiene polymers, and the like. Preferably, ho~ever, the polymeric material is a thermoplastic elastomer composition having desirable properties for this purpose and also making possible a simplified molding techni~ue for molding the floor covering in an essentially single step operation. The preferred thermoplastic elastomer 5 () 'j compositions and the preferred method of molding w;ll be discussed in further detail hereinafter.
Brief Descr~ption o-E the Drawin~s FIGURES 1 and 2 show two embodiments of -the decorative side of an auto mat in accordance with the present invention.
FIGU~ES 3 and 4 show two embodiments of the utility side of mats such as those of FIGURES 1 and 2.
FIGURE 5 is a cross-sectional view taken along the lines 5-5 oE
FIGURE 1.
FIGURE 6 is an enlarged portion of the view of FIGURE ~.
FIGURES 7 and 8 illustrate, in part, one technique for forming a floor covering ln accordance with the present invention.
The structure of the floor covering material of-the present invention and the basic procedures ~or the manufacture thereof will be more apparent from the followinp description of the drawings.
Referring to the drawings, FIGURES 1 and 2 are plan views of the decorative side of an auto mat and show two specific types of design. In FIGURE
1, -the mat 10 is made up of a series of squares of carpet pile 12 alternating with squares of polymeric material 14. .~s shown in FIGURE 2, the carpet pile 16 may be in the form of long, broad strips while the polymeric material comprises alternating thin strips 18. While the preferred floor covering material of the present invention includes at least some fibrous or fabric material, this is not an absolute necessity. For example, the upper surface can be a polymeric material with the design formed as a multi-colored variation. The design itself may take any of a wide variety of desired forms. The design can be formed of blocks or strips as shown in ~IGURES 1 and 2~ respectively, stars, triangles, free-form patterns or the like. Where, in the preEerred embodiment, the decorative surface includes carpet tufting, fibers or fibrous materials, the design may be ~ormed in any one of a variety of ways. For example, the decorati~e effect may be Eormed or woven into the Eabric originally as a multi-0 $

color or sculptured affect, a multi-leveled cut pile or the like. In addition, the design may be formed in the carpeting by crushing the fibers in desired areas in 3 separate heat treatment or preferably during the hereinafter described step of bonding the carpeting to the polymeric material used on the reverse side. In yet another t~clmique, which will be exp:Lained in detail hereinafter, the pa-ttern of alternate carpet piling and polymeric materials may be formed by placing the desired pattern of polymeric materials cut from a thin sheet thereof on top of a solid carpeting and melting the polymeric material onto or into the carpet in a separate operation or preferably during the formation or bonding of the carpeting to the polymeric material forming the reverse side.
FIGURES 3 and 4 show two embodiments of the utility side 20 of the auto mats of FIGURES 1 and 2. The utility side 20 comprises a sheet of polymeric material, preferably having an optimum balance of resistance to abrasion, heat, ultraviolet light9 etc. 9 and can be a solid color or a multi-color pattern. ~Iowever, in any case, the utility side comprises a sheet of polymeric material 22 into which debris-retaining cavities 24 have been formed.
In FIGURE 3, the debris-retaining cavities are shown as circul~r cavities 24.
Debris~retaining cavities are adapted to retain water, dust and/or mud, thus making the utility side of the floor covering material useful during inclement weather and the like while the decorative side can be utilized under normal conditions. FIGURE 4 shows a sheet of polymeric material 26 having formed therein square debris-retaining depressions 28.
FIGURE 5 is a cross-sectional view taken along the line 5-5 of FIGURES 1 and 4. FIGURE 6 is an enlarged portion of the cross-section shown in FIGURE 5.
FIGURES 7 and 8 of the drawings illustrate a convenient way of forming multi-material, multi-level~ and/or multi-colored variations on either the decorative or utility sides of the reversible floor covering product of the present invention.

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In accordance with FIGURES 5 and 8, appropriate s~uares or other appropriate designs of a polymeric material 30 are placed on a release sheet 32, which does not permanen-tly adhere to the mold or any part o:E the mat and, thereEore, can be readily peeled ~rom the mold and the ma-t when molding is completed. Where the thermoplastic sq~lares are to be molded into the carpet-ing on the decorative side of the Eloor covering, -the release sheet would then be placed on top of ordinary carpeting and -the thermoplastic material melted into or onto the carpeting under heat and pressure. This may be done in an ordinary molding operation but is preferably formed from a thermo-plastic material in a single operation by high frequency, flow molding.In a high frequency, flow molding operation, the bottom of the mold would be formed so as to form debris-retaining depressions 24 or 28. A sheet of thermoplastic material would then be placed in the bottom of the mold and -the section of carpeting on top of the sheet of thermoplastic material wi.th the tufting of the carpeting facing upwardly. Thereafter9 the release s:heet 38 of the same character as release sheet 32, having adhered thereto the pattern ot thermoplastic material 30 would be placed on top of the carpeting with the release side of the release sheet and the thermoplastic material toward the carpeting. The mold would then be closed and the molding operation carried out. Thus, in accordance with -this embodiment, the form-ation of the decorative side, the formation of the utility side and the bonding of the carpeting to the thermoplastic material of the utility side is accomplished in one simple operation. To the exten-t that it is desired to form the debris-retaining depressions on the utility side of the floor covering material in a flat bottomed mold, the desired pattern o:E the raised portions 22 or 26 would be formed on and adhered to a release sheet 32. This release sheet with the thermoplastic pattern for the raised por- ~ :
tions would be placed in the bottom of the mold with the raised portions facing upwardly. Thereafter, a sheet oE thermoplastic material would be placed in the mold, -then the carpeting with the tufting facing upwardly and finally if desired, a release shee-t with a pattern of thermoplas-tic material adhered thereto on the top with the thermoplastic material facing the .~ ~ 7 O ~ ' carpet -tufting. Thus, in one molding operation, both the pa~tern on the utility side and the pattern on the decora~ive side could be :Eormed in a single operation without the necessity of making a mold which would form the cavities 24 or 28 on the utility side.
FIGURES 7 and 8 also show a further alternative technique of utilizing a release sheet to support a pattern of thermop].astic material which is thereafter to be bonded to the floor covering product. Specifically a thermoplastic material can be calendered or spread on the release sheet 32 and a pa-ttern then formed by scoring or cutting through -the thermoplastic material in a manner similar to the formation of labels on a release sheet.
Thus, in addi-tion to patterned squares 30, a second thermoplastic pattern 34 would also be present on the release sheet 32, preferably wi-th connecting links 3~ connecting the blocks 34. Thereafter, a second release sheet 38 would be placed on top of the scored thermoplastic material so that one of the two patterns 3Q or 34 will be adhered to the top sheet of release paper 38 while the other pattern of thermoplastic material will remain adhered to the bottom release sheet 32, whèn the two release sheets are separated as shown in FIGURE 8. In this manner, two thermoplas~ic patterns may be formed on two separate release sheets for use in forming two different floor covering materials or for use in adhering ~hermoplastic patterns to the top and the bottom, respectively, of the reversible floor covering product.
When two release sheets are utilized to for~ two thermoplastic patterns, this same technique can be utilized to form a single layer of alternating colored thermoplastics. Specifically, one color such as blocks 30 could be formed on one release sheet, while a contrasting color such as blocks 34 can be formed on a second release sheet. The -two release sheets containing the altern~ting patterns can then be brought together so tha-t the blocks 30 fit between the blocks 34. Thereafter, one of the release sheets can be removed so that a m~lti-colored pattern of thermoplastic material is retained on the other release sheet. The release sheet with the multi-colored pattern can then be bonded to the other half of the floor covering product of the presen-t invention.

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It is, of course, known that release sheet ma-terials may be prepared with any desired degree o~ temporary adhesive properties and thus can be tailored to a wide variety of uses in accordance with the present invention.
~ preferred polymeric compositioll for use in the present invention is an unvulcanized, moldable composition prepared by mixing lO0 parts by weight of a thermoplastic elastomer, at least about 20 parts by weight of an extender oil per lO0 parts by weight of the thermoplas-tic elastomer and at least about 10 parts by weight of a solid, hygroscopic ~iller, having greater than 1 percent by weight o~ absorbed water and capable of retaining a substantial portion of such water at temperatures of at least 100C, per 100 parts by weigh-t of the thermoplastic elastomer, -the ratio of the oil to the hygroscopic filler being from about 0.3 to about 3. The above-mentioned unvulcanized, moldable composition can be simply and efEectively molded ~by disposing the composition in a suitable mold and heating the composition by the application of microwave energy thereto while applying a pressure below about 200 psi for a time just sufficient to melt the composition an~ cause flow o~ the same into the interst.ces of the mold.
The thermoplastic elastomers useful in practicing the present in-vention are normally solid, bloc~ eopolyme~s, characteristicly exhibiting high tensile strength and elongation in their natural condition, that is, in -their green or unvulcanize~ state. Particularly useful are linear block or radial teleblock copolymers. ~ore specifically, useful elastomers are radial tele-block copolymers of butadiene/styrene. Such copolymers are described in more detail in U.S. Patents 3,823,10g; 3,826,776 and 3,95g,545. These polymeræ are prepared by methods well known in the art.
The butadiene/styrene copolymers, discussed above, generally contain about 50 to 90 weight percent butadiene and from 50 to about 10 weight percent of styrene; preferably, from about 50 to 70 weight percent butadiene and about 50 to about 30 weight percent styrene. Copolymers particularly useful in producing compositions in accordance with the present invention are those `- `i J ~4~5 having from about 60 to about 70 weight percent butadiene. When less than about lO percent styrene is employed, the resulting copolymers do not possess the requisite green tensile strength. On the other hand, more than 50 weight percent of the styrene in the copolymer results in a composition in which hardness is increased at the expense o~ elasticity. Useful copolymers will generally exhibit a weight average molecular weight in the range of from about 75,000 to about 500,000 but a range of about 100,000 to about 350,000 is preferable.
It is also within the scope of the present invention to add other polymers to the thermoplastic elastomer in amounts up to about 150 parts by weight of the polymer per 100 parts by weight of the elas-tomer. Such addi-tional polymers are generally solid resinous polymers of a vinyl-substituted aromatic compound, for example, styrene, alphamethyl styrene, etc., alone or copo~ymerized with a monomer such as acrylonitrile or a conjugated diene such as butadiene. Such homopoly~ers and copolymers generally have densities in the range of about 1.04 to about 1.10 gram/cc (ASTM D 792), a tensile strength in the range of from a~out 5,000 to about 12,000 psi (36.5-82.7 N~a), ASTM D-638, and a Shore A hardness rangin~ from about 35 to about 95 (ASTM D-2240) at about 23C.
The previously mentioned ~hermoplastic elastomers may also have certain amounts of the extende~ oil incorporated therein during their manufac-ture. For example, the elastomers may have incorporated therein irom 50 to 6O
parts by weight of oil. Consequently, the amounts of added extender oil re-ferred to herein, and speci~ically in the examples, are amounts in addition to the amounts incorporated in the thermoplastic elastomer during its manu~acture and the amounts of elastomer reEerred to include the weigh-t of the elastomer including the oil added during elastomer preparation. Suitahle extender oils include those well ~nown in the art such as naphthenic, axomatic and paraffinic pe-troleum oils, par-ticularly the naphthenic type.

The thermoplastic elastomer composition may also have added thereto at least about 20 parts by weight of extender oil per 100 parts by weight of the thermoplastic elastomer. Preferred amo~mts of added extender oil include from about 70 to about 350 parts of oil per 100 parts of thermoplastic elastomer and ideally about Z50 to about 300 parts of oil per 100 parts of thermoplastic elastomer.
It is frequently desirable to include other additives well known in the rubber art to the compositions of the present application. S-tabilizers, antioxidants, conventional fillers, reinforcing agents, reinforcing resins, pigments, fragrances and the like are examples of some such additives. Speci-fic examples of useful antioxidants and stabilizers include 2~ hydroxy-5'-methylphenyl) benzotriazole, nickel dibutyldithiocarbamate, zinc dibutyl di-thiocarbamate, tris(nonylphenyl) phosphi-te, 2,6-di-t-butyl-4-methylphenol and the like. Exemplary conventional fillers and pigments include silica, carbon black, titanium dioxide, iron oxide and the like. Polypropylene and poly-styrene are examples of -thermoplastic resins which function as reinforcing agents. A butadiene/acrylonitrile elastomer is an example of an elastomer which functions as a processing aid.
In addition to the above conventional in~redien~s, an unvu~canized, moldable composition of a thermoplastic elastomer can be produced by adding thereto a solid, hygroscopic filler, having greater than 1 percent by weight, and preferably greater than 4.0 percent by weight, of absorbed water and capable of retaining a substantial portion of such water at temperatures of at least 100C, such as, bentonite clay, particularly the Western type, wood flour, ground cork, etc., in addition to the usual amounts of the more conventional fillers and pigments. The hygroscopic filler may be utilized in amoun-ts in excess of about 45 parts by weight of filler per 100 parts of thermoplastic elastomer (phr). These amounts do not include the usual amountæ
o~ conventional fillers and pigments which can be used. Preferably, the 30 hygroscopic filler is utilized in amounts between about 350 and about 500 parts s ~ ~

by weight of filler per 100 parts by weight of thermoplastic elastomer and ideally about 400 parts filler per 100 parts thermoplastic elastomer. Superior products can be produced by employing a particular range of extender oil/hygroscopic filler. Specifically~ the desired weight ratios of oil to hygroscopic filler are 0.3 to 3, preferably 0.5 to 1.0 and ideally about 0.75.
The thermoplastic elastomer compositions may be prepared by any means well known in the art for combining such ingredients, such as solution blending, milling, internal batch mixing, or continuous extrusion of a solid form of elastomer and the other ingredients. ~ rapid and convenient method of preparation comprises heating a mixture of the components to a temperature of about 120C to about 205C, while separate specific embodiments preferably involve stirring a mixture of the components at about 160C to about 205C, preferably about 175C to about 205C or by heating the mixture without stirring in a temperature range of about 125~C to about 200C, preferably about 125C to about 165C. Preferably, the hygroscopic filler is capable of re-taining a substantial portion of its absorbed water at temperatures above the melt temperature of the composition (usually about 160C) and up to the highest temperature utilized in the preparation o~ the composition prior to molding.
One method of preparing a composition comprising a con~jugated diene/vinyl aromatic block copolymer and extender oil involves placing a mixture o~ the copolymer and extender oil in suitable container such as a flat metal pan and heating said mixture, such as in an oven, without agitation at 8 temperature which normally falls within the range corresponding to about the melting point of the elastomer, about 120C, up to about the flash point of the oil, about 200C. Normally and preferably, heating is conducted ~ithin the range of about 125C to about 165C. The composition can be Eormed of the mixture within a time of several seconds to several hours but the mixture is normally maintained at this temperature for about 15 mimltes to several hours.
The time required is dependent upon such -things as the type of the elas-tomer and oil employed, the temperature used and the physical size of the par-ticles - i 3 ~ 5~.~

oE elastomer to be used in preparation of the composition. Furthermore, the time required to make a homogeneous mixture can normally be reduced by physically mixing the rubber and the oil prior to the heating step. Additional addi-tives and formulations can be added -to the elastomer-oil blend prior to or during the heatin8 step. ~fter the heating step, the composition is normally cooled prior to use in fabricating articles.
The composition can be further trea-ted if desired or reqllired in any conventional mixer such as a Banbury mixer or roll mill, particularly if small amounts of undissolved elastomer remain after the oven heating step or if it is desirable to add other ingredients prior to or during the heating step and such have not been uniformly distributed. The additional treatment, if desired, is normally condl-cted within the temperature ran8e of about 75C to about 125C, preferably maintaining the composition below its melting point for a Eew minutes up to several hours, preferably 3 to 1~ minutes. A particularly useful technique is to add the hygroscopic filler in the beginning of the mixing cycle in order to take maximum advantage of heating time and to prevent surface bleeding and overheating when forming the molded articles.
The resultant composition may be in the for~ of extruded pellets, cut dices, preferably as small as possible since smaller pellets provide short ZO heating times and better flow when utilized in flow molding. Ground pelle-ts may also be utilized. Where large area objects are to be made, such as in the manufacture of mats, the composition may be provided in sheet fDrm in order to shorten the heating time and effect better flow during the molding operation.
By utilizing a solid, hygroscopic filler~ as previously discussed, reduced time for incorporating extender oil, ease of incorporation and extremely good dispersion are attained. On the o-ther hand, when using conventional fillers, such as calcium carbonate (whiting) or china clay, particularly at high levels, extremely long mixing times were required and, more importantly, the resultant products were very dry, brittle and completely unusable. Talc, particularly at high loadings, also resul-ted in unexpectably 'J ;) long mixing times and ~ay produce unacceptably stiff and boardy products. By comparlson, products formed from the composition containing the hygroscopic fillers exhibited very good rubberiness and other physical properties.
The composition containing hygroscopic fillers also responds much better to microwave energy heating than materials filled with calcium carbonate, Dixie clays, talc, etc. The mixing difficulties with the china-type clay included excessive stickiness in the mixer which made it impossible to conventionally dump the mixed product.
It is known that the thermoplastic elastomers do not, in and of themselves, respond well to heating by microwave radia-tion. However, the response of the thermoplastic elastomers to microwave radiation is significantly improved by the addition of the hygroscopic fillers. It is believed that the presence and retention of signi~icant amounts of absorbed water by the hygroscopic filler is responsible for such enhancement of the response of the composition to microwave radiation. Consequently, the hygroscopic filler should be capable of retaining a significant amount of its abosrbed water at temperatures above the boiling point of water, preferably above the melt temperature of ~he composition (usually abou* 160C) and up to the temperature utilized in the preparation of the composition for moldin~ and 2a ideally up to the highest temperature reached in the molding operation (generally between about 280 and about 450F ~13~-268C]). If the absorbed water of the hygroscopic filler is driven off during preparation of the mixture for flow molding, the improved response to microwave radiation does not occur, and the advantages during flow molding and of the resultant product, set forth herein, are not attained~ In any event, tests have shown that if the hygroscopic fillers are dried before compounding, the receptivity to microwave radiation is signifiantly reduced. Xn addition, if the water is driven off during flow molding surface pits and/or porosity in-the product result from the evolution of steam. Hence, the compositions containing the hygroscopic -fillers, as deEined, are not as sensitive to overheating as Eormulations containing nonhygroscopic Eillers with significant amounts of absorbed water which will not be retained during flow molding. The above-mentioned ability to enhance the response to microwave radiation is particularly noticeable at high concentrations of hygroscopic filler.
Undesirable evolution of steam can also be controlled by incorporating in the mixture appropriate amounts (about 5 to about 25 parts by weight and preferably 20 parts by weight) of a waterbin~ing agent like calcium oxide, preferably in the form of an oil dispersion.
By definition, the microwave region is that portion of the elec-tro-magnetic spectrum lying between the Ear infrared and the conventional radio frequency portion. While the microwave region is not bounded by deEinition it is commonly regarded as extending from 300,000 megacycles to 1,000 megacycles ~1 mm to 30 cm in wavelength). In most areas of the world certain frequencies have been assigned for industrial uses of microwave energy. For example, in the United States the assigned frequencies ar~e 915 and 2,450 megahertz (M~z), in Europe assigned frequencies are 8g6 and 2,450 megahertz and in ~apan 40 to 5~ megahertz. When a material capable of absorbing microwave energy, rather than reilecting the same or being transparent thereto, is treated with micro-wave energy, heat is produced as a result o~ the absorption of the microwaves.
While, as previously indicated, the compositions referred to above respond well to microwave energy, it is preferred that a polar composition be added as a sensitizer to further enhance the response to microwave energy. Not all polar compounds have been found eEfective in enhancing the microwave energy response of the compositions but there are a large number which have been found so effective. For example, a material selected ~rom among simple and polymeric alkylene glycols and their mono- and dialkyl ethers, ethanol amines and i50-propanol amines and their hydrocarbyl-substituted derivatives and mixtures thereoE have been found particularly useful. Exemplary compolmds include ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 1,4-butylene 3~ glycol, 1,6-he~ylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, thiodiethylene glycol, etc., polyethylene glycols having average molec~llar weights ranging from about 200 to 69000 (commercially available under the tradename "Car'bowax" from Union Carbide Corp., New York~ N.
Y.) polypropylene gylcols having average molecular weights from a'bout ~00 to about 2,000; mixed poly(ethylene)-poly(propylene) gLycols having average molecular weights up to about 6,000 and containing from about 30 to abou-t 90 weigh-t percent ethylene oxide; the monomethyl, monoethyl, and monobutyl ethers of ethylene glycol, propylene glycol and diethylene glycol; the monomethyl and monoethyl ethers of triethylene glycols; the dimethyl and die-thyl ethers of diethylene glycol, dipropylene glycol and trimethylene glycol; the alkanolamines and substituted alkanolamines based on ethanol and isopropanol such as mono-, di and tri-ethanol amine, mono-, di- and triisopropylamine, methylethanolamine, dibutylethanolamine, pheny'ldiethanolamine, di(2-ethylhexyl)ethanolamine, dimethylisopropanolamine, dibutylisopropanolamine, and the like; and mixtures thereof. Other polar compounds such as acrylonitrile/butadiene copolymers 9 acrylonitrile/butadiene blends with homopolymers of poly~inyl chloride an~ styrene/acrylonitrile copolymers are alxo effective. Other materials suitable as polarizing agents include glyceryl diacetate; di(2-hydroxyethyl) dimethylhydantoin; ionomer resins, particularly with other polarizin~ agents and polyphenyleneoxide-polystyrene blends.
Presently preferred compounds include diethylene glycol and trie~henolamine and particularly mixtures thereof and mixtures thereof with polyethylene glycols.
The polar agent will generally be utilized in a range of from about 0.5 to about 20 par-ts by weight per 100 parts by weight of thermoplastic elastomer (phr) and preferably about 0.75 to about 10 parts by weight per l00 parts by weight of thermoplastic elastomer.
While it has been observed that some pitting andfor porosity results when utilizing polar sensitizers in the present process 9 this problem can be solved by avoiding overheating (unnecessarily long periods of exposure to microwave energy), reducing the amount of polar sensitizer employed and/or adding a waterbinding agent like calcium oxide, as previously indicated.
The addition of ethylene/vinyl acetate copolymer also provides an unexpectedly increased response to microwave energy. Specifically, by adding about 25 to about 35 parts by weight, preferably about 30 parts by weight, of such polymer to 100 parts by weight of thermoplastic elastomer the time required for microwave heating can be reduced by about one-half.
One of the distinct advantages of flow molding, utilizing microwave energy as a heating source, is the fact that relatively inexpensive molds can be utilized. For example, molds made of cast liquid silicone compounds may be utilized due to the fact that heating is rapid and pressures below about 200 psi can be utilized.
The process of flow molding is carried out simply by disposing the thermoplastic elastomer moldable composition and the other compo~ents of the product in a suitable mold in pellet form, ground pellet form or sheet form, applying a release sheet such as Teflon on thle top of the composite, closing the mol~ and e~posing the closed mold to microwave energy while applying a pressure up to about 200 psi. ~ suitable microwave unit and one which has been utilized hereinater in the specific examples is a KN unit, ~odel J, manufactured by Compo Industries, Inc., Waltham, Mass. When a sheet of the moldable thermoplastic composition is to be bonded to a woven or non-woven fabric, for example to form a carpeting mat, this is accomplished by placing the moldable composition in the bottom of the mold as previously mentioned, placin~ the fabric, cut to size, on top of the moldable composition, placing a release sheet on top of the fabric, closing the mold and subjecting the same to microwave energy and pressure as previously described.
The following specific examples illustrate the improved results flowing from the use of the compositions and techniques of molding described immediately above.

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Two -tests were conducted utilizing two different compos:itions com-prising butadiene/styrene radial teleblock copolymers. A 6 inch by 6 inch sheet of the thermoplastic elastomer composition having a thickness of 0.170 inch was placed in a suitable mold. A carpeting of polyester was cut to the same lateral dimensions and placed on top of the sheet of thermoplastic elastomer. A release sheet was placed on top of the carpet and the mold elosed.
The specimen was then subjec-ted to high frequency microwave energy from a Compo Industries, Inc. Model J microwave generator having a 10 kilowatt output. The microwave generator was set at 80 percent power. The following table sets forth the overall composition of the pol~meric elastomer composition, the .
heating times necessary to attain various results and the physical appearance of the resultant backed carpeting.

1 ~ 6 ~ r~ O S

Table I
~ 2-~_ B~ltadiene/Styrene Radial Teleblock (70/30 Bd/St) 100 --Butadiene/Styrene Radial Teleblock (60/40 Bd~ - 100 Polystyrene ~5) 70 35 Alphamethylstyrene Polymer -- 35 Silica 30 30 Naphthenic Oil 300 250 Bentonite Clay (Western Type) 400 350 Zinc Steara~ 0.80 0.80 Antioxidant~ ) 0.70 0.70 Ethylene/Vinyl Acetate Copolymer~2) 30 --Ethylene/Vinyl Acetate Copolymer~ ) -- 30 Iron Oxide 2 2 Furnace Black, ~STM N-550 0.5 0.5 Polyethylene Glycol, Molecular Weight About 540 3 3 Triethanolamine 6 6 943.00 843.00 Good bond, but not rubber tear 4 Sec. 6 Sec.
Perfect bond with rubber -tear 5-6 Sec. 7-10 Sec.
Too much penetration into carpet 8 Sec. 12 Sec.
*Ingredients are in parts by weight per 100 parts by weight of the thermoplas~ic elastomer ~phr).
(1) Argus Chemical Corp., Brooklyn, N.Y., Mark~) 1589B.

(2) Melting point about 240~F ~115C).

(3) Melting point about 220F (104C).
~4) Cosden 500 Special, Cosden Oil & Chemical Co., Big Spring, Texas (5) Amoco 18-210, Amoco Chemicals Corp., St. Paul, Minn.
Example II
In another series of tests, yet another composition comprising a butadiene/styrene radial teleblock copolymer was utilized in two tests. In one test ethylene/vinyl acetate copolymer having a melting point of about 240F
(115C) was added to the composition whereas in the other test this material was not employed. The same mold, microwave generator and test procedure was employed except that in this particular case the moldiug composition was placed in the bottom of the mold and the release sheet directly on top of the molding `

i ~ 6 ~

composition to thereby form a mat, such as an outdoor mat without carpeting adhered thereto. It is to be seen as a result of this test that the inclusion of ethylene/vinyl acetate copolymer reduced the minimum heating time to less than half of that required when the ethylene/vinyl acetate copolymer was not employed.
Table II

Outdoor Mat Compound 3* 4*

Butadiene/Styrene Radial Teleblock (60/40 Bd/~) 100 100 Polystyrene 100 100 Silica 50 50 Naphthenic oil 250 250 Bentonite Clay 350 350 Zinc Steara~) 0-8 0.8 Antioxidant 1.0 1.0 Red Iron Oxide 2.0 2.0 Carbon Black 0.5 0.5 Triethanolamine 2 4 4 Polyethylene glycol( ) (4) 3 3 Ethylene/Vinylacetate Copolymer - 30 861.3 891.3 *Excepting thermoplastic elastomer all ingredients are in phr.
(1~ N-isopropyl-N'-phenyl-p-phenylenediamine.
(2) Molecular weight of about 540.

t3) see footnote 4, Table I.

(4) see footnote 2, Table I.
Example III
Another test was conducted utilizing a bentonite clay from another manufac-turer. The composition tested and the results oi this test are set forth in Table III below.

5 ~ 5 Table III
Composition Butadiene/S~ene Radial Teleblock(l) 150 Polystyrene 75 Silica 50 Bentonite Clay (350 mesh) 300 Naphthenic Oil 250 Int. Lubricant: Zinc Stearate ) 5 Ethylene/Vinylacetate Copolymer(225 Skabilizers:
Nickel dibutyldithiocarbamate 0.5 Zinc dibutyldithiocarb~te 0.5 ~ow Density Polyethylene~ J 1.0 Parafin ~ 3 Desiccant 20 Carbon Blac~5) 5 Sensitizers 16 901.O

Specific Gravity 1.29 ZO 300~ Modulus 160 Tensile Strength 200 Elongation 480 Shore A Hardness 43 Melt Index, Condition E 100 *Parts by weigh~

(1) 60/40 Bd/St + 50 phr oil (2) Melting point about 240~F ~115C) (3) Density of 0.92 g/cc, melt index of 70 (A5TM D 1238-65, Condition E) (4) 80 wt. % ground CaO in high flash process oil (Desi Cal, Basic Chemicals, Cleveland, Ohio) (5) Polyethylene glycol (Molecular Wt. about 5403 + triethanolamine in equal proportions.
(6~ see footnote 4, Table I.
It has also been found that ground cork is an effective hygroscopic filler for use in the present invention. Ground cork has the additional ad-vantage of lowering the weight of the final product.
Example IV
Table IV below shows another series of two tests in which the same bentonite clay as in Example III was utilized and a third tes-t in which wood flour was substituted for part of the bentonite clay. In addition to the suit ability of wood flour as a hygroscopic filler, runs 7 and 8 show that good results can be obtained in flow molding the compositions o-E the present inven-tion witho~ the addition of polar sensitizers and run 6, as compared wlth runs7 and ô, shows that overheating should be avoided when polar sensiti~ers are added. While it has been found tha-t wood flour is not as effective as bentonite clay, it does in Eact function in the same capacity and is useful in accor~ance with the present invention.
Table IV
Composition 6* 7* 8*
Butadiene/Styrene Radia ~ leblockll~ 150 150 150 Hi8h Density Polyethylenéi`100 100 100 Bentonite Clay (350 mesh) 300 300 200 Wood Flour (Douglas Fir) - - 100.
Ethylene-Pro~ylene-Diene Terpolymer Elastomer 2 25 25 25 I:ow Density(~Jolyethylene( ) Antioxidant Heat S-tabilizer-Zinc Dibutyldithio-carbamate Paraffin Wax 2 2 2 Desiccant: CaO dispersed in oil lS 15 15 Int. Lubricant: Zinc Stearate 4 4 4 Naphthenic Oil 100 100 100 TiO2 (Pi$ment) (4) 6 6 6 Coumarone-Indene Resin 10 10 10 Sensitizers:
Triethanolamine 4 Polyethylene Glycol(5) 4 H.F. Flow-Nolded in Compo-Industries, Inc. Model J, 10 kw Machine, Output setting 78.
Time, Sec. 5 5 5 Grid Plate Rectifer, D.C. Milliamperes 0.67 0.62 0.59 Radio Frequency Voltage, D.C.
Microamperes 78 78 78 Mold Flow GoodV.Good Good Molding Time Before Pitted Surface, S~c. 7 13 15 *Parts by weight (1) 52/48 Bd/St. -~ 60 phr oil (2) Density of 0.92 g/cc, melt index of 70 (ASTM D 1238-65, Condition E) 40 (3) Argus Chemical Corp, Brooklyn, N.Y., Mark~R) 1589B
(4) Cumar LX-509, Neville Chemical Corp.
(5) Molecular wt. about 540.

(6) Marlex 4270, Phillips Petroleum Co., Bartlesville, OK;
density of 0.942 g/cc & 7 melt lndex (ASTM D 1238-6~T, Condi-tion E).

(7) Nordel 1500, DuPon-t de Nemours, E. I. & Co., ~ilmington, Del.

~ 3 ~O S

Example V

In order to illustrate the advantages of the use of bentonite clay as a filler as opposed to whiting or calcium carbonate another series of tests was conducted comparing these two materials. Again, the same microwave generator, the same mold and -the same general procedure were employed to produce a slab--type molded sheet.
At the outset it was observed that the whiting compositions were quite difficult to mix and had a sticky, very soft composition.
The resuLts of these tests are set forth in Table V below wherein it is apparent that the articles molded from the compositions containing bentonite clay, in essentially the same mesh size as the whiting, were quite fle~ible whereas those produced with whiting, as an additive, were stiff and boardy. It is also apparent that the minimum heating time required was substantially greater for the compositions containing whiting.

~ ~ 6~'jotj Table V
Compo_ d _ 9:~ 10* 11~ 12 Butadiene~Styrene Radial Teleblock (70/30 Bd/St)~ ) 150 150 150 150 Low Dens. Polyethylene~l100 100 100 100 Silica 50 50 50 50 Naphthenic Oil 200 200 200 200 2inc Stearate o.8(2) 0-8 2) 0-8 (3~ 0-8 (3) Stabilizers 0.7 0.7( 0.950.95 Gamma mercaptopropyltri-methoxysilane - - 4 4 Polarizing Agents(4) 8 8 8 8 Bentonite Clay, 325 Mesh400 - - 400 Whiting - 400 400 __ -909.5 909.5 913.75913.75 Mixing ~bservation OK Sticky, Sticky, OK
V. So~t ~. So~t Minimum Heating Time (Seconds) 12 20 60 35 Melt Flow, 5Kg at 190C 327 589 610 216 Shore A Hardness 63-6639-45 58-62 72-75 Other Physical Properties About Equal Molded Products Flexible Boardy Boardy Flexible *All ingredients are in parts by weight.
~*Basic copolymers included 50 phr extender oil added during manufacture.
(1) Density of 0.92 g/cc, melt index of 70 (ASTM D 1238-65, Condition E).
(2) 0.3 Zinc dibu~yldithiocarbamate 0.5 Nickel dibutyldithiocarbamate (3) 0.4 Zinc dibutyldithiocarbamate 0.55 Nickel dibutyldithiocarbamate (4) 4 Triethanolamine 4 Polyethylene glycol of about 540 molecular weight.
Example VI
In yet another series of tests, bentonite clay was compared with whiting in lower concentrations u~der essentially the same conditions as the previous examples.
Again, it is to be observed that the products containing the ben-ton-ite clay were highly flexible whereas those produced Erom -the compositions containing whiting were stiff. In addition, it can also be observed that again 2~

450~

the minimum heating time for proper molding was substantially greater when utilizing whiting as opposed to bentonite clay.
Table VI
Compound 13* 14~ 15* 16 Butadiene/S-tyrene ~adial Teleblock (60/40 Bd/St) 100 100 - -Butadiene/Styrene Radial Teleblock (52/48 Bd/St - 60 phr oi~) - - 150 150 Alphamethylstyrene Polymer 60 60 40 40 Silica 30 30 30 30 Naphthenic Oil 70 70 75 75 Zinc Stear~ 0.3 0.3 0.75 0.75 Stabilizer 2 0 5 0-5 0.5 0.5 Ethylene/y~ylacetate Copolymer( )20 20 30 30 Desiecant 4 15 15 15 15 Sensitizers( )(5 3 3 6.5 6.5 Nitrile ~ubber ) - - 8 8 Bentonite Clay, 325 Mesh 45 - - 58 Whiting - 45 58 343.8- 343.8413.75413.75 Mixing Observation OK OK OK OK
Melt Flow, 2160g/190C 48.8 102 32.8 13.9 HF Flow-Molded Tensile Slabs, 10kw Model J Compo-Fit Machine:
Minimum ~eatin8 Time 15" 30" 20" 10"
300% Modulus, psi, 20" - - 160 220 Tensile 9 p9i, 20" - - 400 460 Elongation, %, 20" - - 660 640 Hardness, Shore A, 20" - - 6~-71 72-79 Molded Products Flexible Stiff Stiff Fle~ible *Ingredients in phr (based on 100 parts by weight of thermoplastic elastomer).
(1) 0.5 Tris(nonylphenyl)phosphite.
(2) Melting point about 240F.
(3) 80 Wt. ~ ground CaO in high flash process oil (Desi Cal, Basic Chemicals, Cleveland, Ohio).
4) 50/50 by weight triethanolamine and polyethylene glycol of about 540 molecular weight.
(5) Powdered butadiene-acrylonitrile elastomer~ 50 Mooney viscosity, M~-4, 210F, (Hycar 1452 P-5D, B.F. Goodrich Chemical Co., Cleveland, Ohio).
(6) see footnote 5, Table I.
Example VII

4 ~

The effect oE substituting carbon black for all or part of the hygroscopic filler was evaluated in the tests set forth in Table VII below:
Tab]e VII
Composition 17 18 19 20 Butadiene/S~ene Radial Teleblock(l) 140 140 140 140 Polystyrene 75 75 75 75 Silica 45 _ 45 ~5 Bentonite (350 mesh) 300 300 150 Carbon Black - 45 150 300 Naphthenic Oil 250 250 250 250 Zinc Stearate 2 5 5 5 5 Ethylene/Vinylacetate Copolymer( ) 25 25 Z5 25 Stabilizers:
Nickel Dibutyldithiocarbamate 0.5 0.5 0.5 0.5 Zinc Dibutyldithiocarbamate 0.5 0.5 0.5 0.5 ParaEfin Wa~3~ 3 3 3 3 Sensitizers 16 16 16 16 Desiccant: CaO dispersed in oil (4) 20 20 20 20 Styrene/Butadiene Copolymer Rubber 15 15 15 15

8~5 895 875 895 Calculated Specific Gravity 1.29 1.28 1.26 1.24 Mi~utes Cure, HFFM~ Time, Secs. 5 2 4 6 300~0 Modulus, psi 110 70 140 Tensile Strength, psi 150 130 140 300 /0 Elongation 450 540 300 190 Shore A Hardness 30 22 42 35 Melt Index Flow, 325 grams at 190C 4.6 37.4 0.65 4.4 Mold Flow @ 2", Rating 1-5, 1 is Best 2 2 3 5 Time for Equivalent Mold Flow, Secs. 2" 2" 8" 8"
Scrub Test on White Paper, Marking Non- Non- Sligh~ Heavy Oil Bleedout on Brown Paper After 3 weeks Slight Medium Slight ~one A~ter 5 weeks Medium ~eavy Medium Slight (1) 60/40 Bd/St + 50 phr oil (2~ Molecular weight about 240 (3) Triethanolamine ~ Polyethylene glycol (Molecular W-t.
about 540) in equal portions (4) Emulsion polymerized a-t 41F containing 50 parts carbon black per 100 parts rubber ~5) Cosden 5~0 Special, Cosden Oil & Chemical Co., Big Spring, Texas It is to be observed from Table VII that, while carbon black has the effect of reducing the bleed out of extender oil, it has a number o disadvan-tages when compared with bentonite clay. Specifically, when 1/2 o-E the benton-ite clay was replaced with carbon black the time necessary ior molding was increased and the melt Elow of the composition was reduced. When the carbon black replaced all oE the bentonite clay the tensile, modulus and hardness !~ :1 6 ~

increased, as did the molding time necessary and mold Elow was Ellrther reduced.
In addition, a molded shee-t of the product yroduced heavy black marks when scrubbed on a light colored surface.
Example VIII
Yet another series oE comparative tests was conducted as set forth in Table VIII below:
Table VIII
Composition _ 21 22_ 23 24 _ 25 26 Butadiene/Styren~l~adial Tele7~ck 150 Polystyrene 75 ) SAME
Silica 45 Bentonite (350 mesh) 300 Bentonite (325 mesh) 300 Royal King Clay (Hard China) - - 300 - -Suprex Clay ~Hard China) - - - 300 Gamoco Whiting - ~ ~ 300 Paragon Clay (Soft China) - - - - - 300 Naphthenic Oil 250 Zinc Stearate 5 Ethylene Vi ~acetate Copolymer 25 Stabilizers:
Nickel Dibutyldithio-carbamate 0.5) Zinc Dibut~dithiocarbamate 0.5) SAME~
Antioxidant 0.5) Paraffin Wax 4 3 Styrene/B~t~diene~ ) 16 Desiccant 20 Carbon Black 5 895.5 895.5 ~95.5~95.5 895.5 895.5 Speci.~ic Gravity 1.2~ 1.29 1.29 1.29 1.29 1.29 Mixing Time, Min. 10 14 14 12 - 18 Mixing, Dumping, Charact. Good Good Poor Fair Would Fair Not Mix ~ea-tin~ TimeGrid Plate Rectifier, Max.
Secs.
3 .5~.62 .36 .38 - .36 6 .54.56 .36 .36 - .3 Arc Arc - - - -12 - - .36 .36 - - - - - .35 5 0 .~

Mold Flow Char~ct.
Secs.
3 Good Good No Elow No Flow - No Flow 6 Excel- Excel- (Little (~ittle - (Little lent lent Flow) Flow) Flow) Over- Over- - - - -heat heat 12 - - ~air Fair - - - - - Fair Physical Properties 30% ModuLus, psi 130 130 190 200 - 150 Tensile Strength, psi 200 180 200 220 - 170 ~longation, % 460 490 330 390 - 370 Shore A Hardness 34 39 3~ 34 - 32 (1) 60/40 Bd/St + 50 phr oil (2) Molecular Weight about 240 (R) (3) Argus Chemical Corp., Brooklyn, N.Y., Mark 1589B
(4) Emulsion polymeri~ed at 41F containing 50 partc carbon black per 100 parts rubber (5) 80 Wt. % CaO in high flash process oil (Desi Cal, Basic Chemicals, Cleveland, Ohio) (6) Cosden 500 Special, Cosden Oil & Chemical Co., Big Spring, Texas Table IX shows the comparative moisture contents of the fillers utilized in the previous comparative examples. While the nonhygroscopic Hi Sil 233 (Silica) and Royal King Clay (Hard China) exhibi-t high initial water contents, it is obvious Erom the previous examples that these materials are inferior to the hygroscopic fillers of the present invention, due to the facts that the absorbed water is readily driven off as soon as the temperature is abo~e the boiling point of water, usually in the preparation of the compositions prior to molding, and any chemically-bound water, which is not driven off apparently does not function in the same manner, in the present process~ as does absorbed water.

0 ~

Table IX
Fi r Supplier % Moisture 1. Royal King Clay (Hard China) H. M. Royal, Inc. 14.0 2. Western Ben-tonite H. M. Royal, Inc. 9.0 3. Hi Sil 233 (Silica) PPG Industries 5.3 4. Philblack N550 (Carbon Black) Phillips Petroleum 1.0 Max.
5. Wood Flour Wood Flour, Inc. 5.d - 8.0 6. Ground Cork Dodge Cork Company 4.0 - 9.0 7. Suprex Clay (~ard China) J. M. Huber 1.0 Max.
8. Gamoco Whi-ting Georgia Marble 1.0 Max.

9. Paragon Clay (Soft China) J. M. Huber 1.0 Max.
Some of the advantages oi the hygroscopic fillers over nonhygroscopic fillers, such as whiting and china clay, etc. can be summarized as follows:
Shorter mi~ing times.
No stickiness in the mixing chamber or o~ roll mills.
Shorter heating time in a high Erequency field.
More suitable melt flow, i.e., higher than china clay and lower than whiting.
Higher hardness than whiting and about the same as china clay.
Equal or slightly better stress/strain properties but considerably better tear ~hand test).
Considerably better flexibility than whiting and especially china clay.
Example IX
In accordance with this example, a reversible mat of the type illustrated in FIGI~ES 1, 4, 5 & 6 was molded.
The following thermoplaætic composition was utiliæed for -the portions of mat which comprise polymeric materials. All quantities are given in parts by weight.

~ 3 ~5~5 Table X

Butadiene/Styrene(a) 150 Radial Teleblock( ) 2.4 Polypropylene Resin( ) 60 Polystyrene Resin( ) 40 Mineral Filler ~350 Mesh)( )400 Silica 5.6 Naphthenic Oil 150 Zinc Stearate S-tabili~ers(f) 2 CaO dispersed in oil(g) 20 Sensitizers(h) 8 Microcrystalline wax(i) 2 Coumarone-Indene Resin~i) 10 (a) 52/48 Bd/St. + 60 phr oil (b) 60/40 Bd/St. ~ 50 phr oil (c~ Marlex HGZ~040-02, Phillips Petroleum Co.

(d) Cosden 500 Special, Cosden Oil Chemical Co., Big Spring, Texas (e) Bentonite clay (Western) (f) Tris(nonylphenyl~phosphite, 1 part dilaurylthiodipropionate, 1 part (g) Desiccant, see ~ootnote 3, Table VI
(h) See footnote 5, Table III
(i) Sunolite 240, Witco Chemical Corp., New York, N. Y.
(j) Cumar ~X-509, Neville Chemical Corp., Pittsburgh, Pa.
The above composition was sheeted out to an approximate thickness of about 0.100 inch. A piece corresponding to the lateral dimensions of the mold was stamped out and then placed in a mold having protrusions Eormed on the bottom thereof adapted to form debris-retaining depressions, such as despressions 28 of FIGURE 4. A piece of carpeting having lateral dimensions corresponding -to those of the mold was placed on top of the thermoplast:ic sheet with its pile side up. A checkerboard pattern of thermoplastic squares was adhered to a sheet of release paper whose later dimension corresponded to those of the mold. The release sheet was then placed in the mold on top of the carpet with the thermoplastic facing -the top of the carpet. The mold was closed and subjected to microwave energy, utilizing the same energizing unit of the previous e~amples, for a period of 6 seconds. The mold was opened, the re]ease sheet peeled off and the mat removed from the mold.
The resultant product had all of the properties and characteristics heretofore set forth for the reversible mats of the present invention as well as the improved characteristics and properties il]ustrated by the previous examples for the preferred thermoplastic molding compositions and flowing from the preferred techniques of high frequency flow molding.
~ hile specific materials, amounts thereof and operating conditions and procedures have been referred to herein, numerous variations and mo~ifications thereof will be apparent to one skilled in the art and the present invention is considered to include such variations and modifications.

3i

Claims (10)

The embodiments of the invention m which an exclusive property or privilege is claimed are defined as follows:

1. A flexible, reversible floor covering, comprising:
(a) a first, flexible sheet of material, having a decorative pattern formed on an exposed surface thereof, of sufficient strength and wear properties to form a traffic-bearing surface; and (b) a second, flexible sheet of a polymeric composition comprising a butadiene/styrene block copolymer, containing about 50% to about 90% by weight of butadiene and about 50% to about 10% by weight of styrene, and a microwave energy enhancing agent, in an amount sufficient to increase the response of said composition to microwave energy of sufficient strength and wear properties to form a traffic-bearing surface and having a pattern of depressions, of sufficient depth and lateral dimensions to receive and retain debris, formed on an exposed surface thereof;
(c) said first sheet and said second sheet having been bonded in back-to-back relation, without an adhesive, by a single flow molding step utilizing microwave energy as a heat source.

2. A floor covering in accordance with claim 1 wherein the decorative pattern comprises different colored fibrous materials.

3. A floor covering in accordance with claim 1 wherein the decorative pattern comprises different levels of polymeric materials.

4. A floor covering in accordance with claim 1 wherein the decorative pattern comprises different levels of fibrous materials.

5. A floor covering in accordance with claim 1 wherein the decorative pattern comprises different colored polymeric materials.

6. A floor covering in accordance with claim 1 wherein the decorative pattern comprises alternate areas of polymeric material and fibrous material.

7. A method of forming a flexible, reversible floor covering comprising:
(a) depositing a first, flexible sheet of a polymeric composition comprising a butadiene/styrene block copolymer, containing about 50% to about 90% by weight of butadiene and about 50% to about 10% by weight of styrene, and a microwave energy enhancing agent, in an amount sufficient to increase the response of said composition to microwave energy, of sufficient strength and wear properties to form a traffic-bearing surface in the bottom of a mold having a top and a bottom section;
(b) depositing a second, flexible sheet of material on and in direct contact with said sheet of polymeric material;
(c) depositing a release sheet in contact with said second sheet of material;
(d) closing said mold, whereby the -top of said mold is in contact with said release sheet;
(e) heating the interior of said mold by exposing the same to microwave energy to a temperature and for a time sufficient to cause flow of said polymeric material and to bond said first sheet and said second sheet;
and (f) simultaneously with said bonding, forming a utility surface of debris receiving cavities, of sufficient depth and lateral dimensions to receive and retain debris, in the bottom of said first sheet; and (g) simultaneously with said bonding, forming a decorative surface on the top of said second sheet.

8. A method in accordance with claim 7 wherein the utility surface is formed by a plurality of protrusions in the bottom of the mold, of dimensions equal to the dimensions of the cavities.

9. A method in accordance with claim 7 wherein the utility surface is formed by disposing a release sheet in the bottom of said mold, before depositing the first sheet therein; said release sheet having disposed thereon protruding patterns of the polymeric composition of a form and size to form the periphery of the cavities.

10. A method in accordance with claim 7 wherein the decorative surface is formed by a projecting pattern of the polymeric composition adhered to the release sheet and which simultaneously bonds to the second sheet.