US3473240A - Footwear having improved block copolymer foxing adhesion - Google Patents

Description

3,473,240 FOGTWEAR HAVING IMPROVED BLOCK COPQLYMER FOXIYG ADHESION .lon W. Martin, Les Aiarnitos, .lohn L. Snyder, Long Beach, and Gienn R. Himes, Torrance, Calif., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Apr. 8, 1968, Ser. No. 719,721 Int. Cl. A43h 1/02, 9/00 US. Cl. 36-4 Claims ABSTRACT OF THE DISCLGSURE Footwear assemblies are provided comprising a textile upper, a polymer soling and a block copolymer foxing wherein the foxing adhesion to the upper in wear and under wet conditions is substantially improved by pretreatment of the upper fabric with certain polymeric materials having a dielectric constant at least as great as that of the block copolymers, the assemblies having wet peel strength which is at least 70% of the dry peel strength.

This invention relates to improvements in the bond of foxing to footwear having textile uppers. More particularly, it relates to footwear uppers bearing a coating which promotes adhesion of foxing comprising block copolymers.

Numerous types of footwear are designed to perform their function under a variety of physical conditions. The sole of some fabric upper shoes is attached to the upper by a foxing strip. While it is reasonably an easy task to design a shoe assembly which has a high bond strength of polymeric foxing to fabric under conditions of dry peel measurement, the bond of foxing to fabric often leaves much to be desired in use, especially when exposed to moisture as it is on the foot. This is probably due in substantial part to the lack of true adhesion of the foxing material, which is usually nonpolar or substantially so, to the textile, which is often polar in character, as in the case of cellulosic fibers and the like. Textile top shoes, in particular, are subjected to a number of situations which unless adequately met, result in disintegration of the assembly. Thus, under the influence of perspiration or rain, the foxing strip around the base of the upper may tend to separate especially at the area of flexing. Also, when washed in the presence of hot water and detergents, foxing separation may be a severe problem. More specifically, the problem of wet bond strength is especially apparent in such footwear as canvas topped shoes. In such articles it is not only important to maintain a high degree of flexibility, improve abrasion resistance and dry peel strength but also and perhaps more importantly to maintain a high foxing to fabric bond when the shoes are subjected to fiexure especially in moist conditions.

It is the usual practice in the trade to laminate two layers of canvas together with a polymeric combining paste and then to bond the canvas laminate to a thermoplastic or elastomeric sole portion of the shoe with a strip applied either simultaneously or subsequently which is known as a foxing strip. This foxing is the strip of material which covers the upper part of the sole edge and the lower part of the canvas upper edge Where the upper and sole meet. In many instances in the past, the combining paste has been made out of thermoplastics such as PVC or vulcanized material such as vulcanized SBR, polychloroprene and the like. The vulcanized polymers are highly intractable materials once they have been 1 nited States Patent 0 3,4732% Patented Oct. 21, 1969 thermoformed. Moreover, it has been found by experience that these combining paste compositions lack the ability of physically promoting adherence of block polymer foxing especially under wet conditions.

Canvas top shoes and the like must be marketed under highly competitive conditions. Consequently any ecomomies which may be effected in the manufacture of the articles improve the competitive position thereof. The necessity for vulcanizing prior art compositions used as foxing or other footwear components reduces this competitive position and consequently it would be highly desirable to avoid vulcanizing and at the same time to provide improved bond and especially wet peel strength for foxing compounds.

It is an object of the present invention to improve the physical properties of footwear assemblies. It is a particular object of the invention to provide improved footwear as materials to result in superior wet peel strength.

Now, in accordance with the present invention, an improved shoe construction is provided possessing substantially increased foxing adhesion even under wet conditions which comprises, a textile upper, a tie coat thereon at least in the area to be contacted by the foxing, a foxing strip and a sole, both the foxing and sole comprising an unvulcanized block copolymer as defined hereinafter. The textile tie-coat foxing assembly must have a Wet peel strength at least as high as the dry peel strength thereof due to the high degree of affinity of the tie coat to both the textile and the block copolymer foxing compound. The tie coat for this purpose must be a polymeric substance having the following properties:

(1) A dielectric constant at least equal to that of the block copolymer, i.e., at least about 3.0 at 60 cycles, at 23 C.;

(2) Tensile strength of at least pounds per square inch at 23 C.

The difference between wet and dry peel strength appears to be one of the most important defining qualifications. In effect, it describes the adherence of the tie-coat polymer both to the textile upper material and to the block polymer foxing compound under both wet and dry conditions which any textile-top footwear will encounter in normal use.

The next most important criterion of the tie coat polymer is with respect to tensile strength, which should be at least 150 pounds per square inch (p.s.i.), and preferably at least 350 psi. at 23 C. This limitation is based on tensile values obtained on compression molded tensile specimens at 23 C. using a crosshead speed of 20 inches per minute (ASTM test number D4l2-62T, Die D). The tensile strength values given and the limitations placed thereon will either be on unvulcanized or on vulcanided polymers, depending on their common usage in this respect.

The chemical classes of polymers especially useful in tie-coat compounds include, among others, polymers of vinyl halides, amine-aldehyde copolymers, phenolics, phenol-aldehyde copolymers, halohydrocarbon polymers, epoxy resins, cellulose ethers and esters, ABS polymers, polyurethanes, acrylate polymers, methacrylate polymers and the like, as long as they meet the physical criteria set out hereinbefore. The following table gives tensile strength, dielectric constant and solubility parameter data of polymers especially suitable for use in tie-coat compounds. A further preferred qualifying description of the tie coat is one which reduces the area of foxing separation by a factor of at least 2, during actual wear tests compared with shoes not having the foxing tie coat.

TABLE A.

Tensile Dielectric strength, p.s.i. constant (ASTM D638 (ASTM D150) or ASTM D651) 60 cycles Styrene-butadiene 3 AB S 4, 000 2. 4-5. Methyl methaerylates 7, 000 3. -4. 5 Methyl methacrylate-alph rene copolymers. 9, 000 3 Ethyl cellulose 2, 000 3-4. 2 Cellulose acetate- 1, 900 3. 5-7. 5 Cellulose acetate butyrate. 2, 600 4-5 Epoxy resins 4, 000 3-5. 5 Polyvinylidene fluoride 7, 000 8. 4 Melamine-formaldehyde resins. 5, 000 7 Nylon 7, 000 4-4. 0 Alkyd reslns 5. 1-7. 5 Silicones 8, 000 3. 3-5. 2 Urea-formaldehy 5, 500 7-9. 5 Polyurethanes" 4, 500 7. 6 Polyvinyl buty'ral 500 5. 6 Polyvinyl chloride. 1, 500 3-9 Phenol-formaldehyde. 10, 000 5-6. 5 Polychloroprene 3, 000 1 6. 5-8. 1 Polyvinylidene chloride 3T 1 IKC.

The art of processing each of these classes of polymers is well known insofar as the necessity of vulcanizing or curing is concerned. Experts in the art of polymer formulation will be able to determine what, if any, such treatment is required in each individual case.

It is important to emphasize that, while the tie-coat polymer may be vulcanized, if necessary, it is only contemplated to use unvulcanized block copolymers in the foxing and sole compounds. Thus, only a physical bond (as contrasted to a chemical linkage) unites the foxing with the textile upper.

While the assembly in its broadest aspects thus contemplates the formation of a high bond strength single textile upper bearing a foxing strip comprising a block copolymer, a more particular aspect of the invention contemplates the situation in which two textile sheets are combined by means of an intervening combining composition. The term combining compounds is used in the shoe trade for the composition which is utilized for laminating one layer of textile to at least a second layer, resulting in a composite textile especially designed for the preparation of textile shoe uppers. More particularly, the compositions performing the function of combining compounds comprise not only the block copolymer but compositions in which the block copolymer is modified with one or more ingredients including especially polystyrene, tackifying resins, hydrocarbon extending oils and/or mineral particulate fillers, as is more particularly described hereinafter in greater detail. Other combining compounds may comprise vulcanized SBR, polychloroprene and polyvinyl chloride.

The most important application of the present invention at this time is in the manufacture of sport shoes generally referred to as tennis shoes or the like. The problem of foxing separation referred to hereinafter is substantially eliminated or largely minimized by the use of the present invention. As the data given hereinafter will show, the application of a polymeric tie coat to at least the area of the textile upper contacted by the foxing and thereafter manufacturing shoes such as by injection molding of a block copolymer foxing and a soling onto this upper results in a surprisingly improved bond of foxing to upper during use.

The textile involved in the articles of the present invention may be either woven or nonwoven as the case may be and if two or more layers of textile are present they may be either similar or dissimilar. The textile uppers may be impregnated with a superficial amount of block polymer, if so desired, for the purpose of improving abrasion resistance and reducing water permeability.

While uppers often are cotton canvases exclusively, they may be combinations of cotton with synthetic materials or regenerated cellulose such as rayon or may comprise at least in part textiles such polyester, nylon and ithe like. The present invention moreover contemplates the formation not only of sport shoe uppers but the preparation of innersoles, toe stiffeners, heel stiffeners and clothing interlays.

The block copolymers to be used in foxing and optionally in soling and combining compounds are either linear or branched, i.e., star-shaped, and have the general configuration Disregarding any residue of a coupling agent, suitable star-shaped molecules could be better represented as AB(BA) If the copolymer is not hydrogenated, the blocks A comprise poly(vinyl arene) blocks, n is an integer from 1 to 5, while the block B is a poly(conjugated diene) block. The blocks A normally have number average molecular weights, as determined by intrinsic viscosity measurements which have been correlated with primary molecular weight measurements including osmometry and radio tracer measurements of tritium terminated polymer, of between about 8,000 and 45,000, while the conjugated diene polymer block has a number average molecular weight between about 25,000 and 150,000. If the copolymers are hydrogenated, the molecular weight ranges remain in about the same ranges. Two preferred species of such block copolymers include those having the block configuration polystyrene-polybutadiene-polystyrene and polystyrene-polyisoprene-polystyrene as well as their hydrogenated counterparts. The hydrogenated counterpart of the second of the above defined block copolymers is of special interest, not only because of its high stability but because of the elastomeric nature of the hydrogenated midsection which resembles that of an ethylene-propylene rubber while the end blocks either remain as polyvinyl arene blocks or, if hydrogenated, become saturated blocks made up of polyvinylcyclohexane units. Thus, the fully hydrogenated preferred species has a block configuration which corresponds closely to p0lyvinylcyclohexane-ethylone-propylene copolymer-polyvinylcyclohexane.

These particular block copolymers have the unique feature of attaining the stress-strain properties of an elastomer without the requirement that it be subjected to curing or vulcanization. Thus, they are sharply differentiated from other rubbers such as natural rubber, polybutadiene, SBR and the like which require vulcanization in order to attain satisfactory stress-strain properties.

The block copolymers of this invention may be the major polymeric material utilized in the foxing but they may, if preferred, be modified by the presence of other components such as plasticizers or other polymeric coating materials. Plasticizers such as rubber extending mineral oils or esters may be employed and polymers such as polystyrene, polyethylene, polypropylene and the like may be incorporated with the block copolymers.

The compositions which are contemplated for the present purpose especially where canvas top sport shoes are concerned include particularly at least foxing compounds which are combinations of parts by weight of the subject block copolymers with 5-130 parts by weight each of polystyrene and extending oil. Normally, still further modifications of such compositions are possible and are utilized for improving the flexibility and reducing the modulus of the compositions if desired as well as for reducing the overall cost. Thus, the presence of 5-130 parts by weight of a hydrocarbon extending oil is also contemplated as is the presence of a substantial amount of an inorganic finely divided particulate solid especially in the order of 5-200 parts by weight per 100 parts of the block copolymer.

Polymer extending oils are useful both for the purpose of reducing the cost of the compositions and more particularly for imparting better processing and physical properties thereto. This is especially important as the average molecular weight of the block copolymer increases. In some instances in the higher molecular weight ranges processing becomes extremely difiicult at ordinary processing temperature short of decomposition temperatures in the absence of extender oils. It is preferred that the extender oils be those utilized for extending other polymers and particularly rubbers and that these have no more than about 50% aromatics and greater than about 45% of saturates, usually naphthenic types of hydrocarbons.

The extender oils should be utilized in amounts between about 2 and 300 parts (preferably 5-130 parts) by weight per 100 parts by weight of the block copolymer.

Pigments are normally utilized in as large amounts as possible while still maintaining desired physical properties; usually this will be an amount between about 25 and 400 parts by weight per 100 parts by weight of the block copolymer.

The incorporation of these materials together may take place on the usual polymer processing mills and internal mixers or in an extrusion type of apparatus or may be composited by means of other masterbatching processes, particularly a solution masterbatch. In this process a solution of the block copolymer is formed in a solvent which is either a non-solvent or only a partial solvent for polystyrene. Specifically, such a solvent will comprise 21-85% by volume of an open-chain hydrocarbon having from 4-8 carbon atoms per molecule and 79-15% by volume of a cyclic hydrocarbon having from 5-8 carbon atoms per molecule. The polymer solution (cement) so formed is then combined with 5-200 parts by weight of polystyrene and 25-400 parts by weight of the finely divided particulate solids per 100 parts by weight of the block copoly- I mer. The mixture is then subjected to coagulating procedure so as to isolate the solid materials from the solvents. This is best effected by forcing the mixture into a vessel containing steam and hot water under such conditions that the solvent is flashed off and the composition becomes suspended in a bath of water in the form of crumbs. These are then separated from the water by screening or decantation and subjected to grinding if necessary to effect relatively uniform particle size after which the particles are subjected to drying procedures as in moving belt drier, expander drier or the like. The use of this particular type of solvent accentuates the effective ness of the polystyrene in retaining the finely divided particulate solids. Apparently, the polystyrene exists under these conditions as a gummy highly swollen material which aids in the incorporation of the particulate solids.

In accordance with the present invention, the bond of block polymer foxing to textile uppers is unexpectedly retained even under wet conditions such as encountered in normal wear, wet weather, washing or perspiration by the application of at least a superficial coating or impregnation on at least on that part of the upper which is later to be contacted with the foxing compound. The materials employed for this purpose are listed and described hereinbefore. Polyvinyl chlorides are especially effective. The polyvinyl chlorides, a preferred class of tie-coat polymers in the present assemblies, include thermoplastic polymers produced by the polymerization of a monomer mixture containing not less than 70% by weight of vinyl chloride and preferably more than 90% by weight thereof. The monomers may comprise entirely vinyl chloride as the sole monomer. In addition thereto, copolymers and interpolymers of vinyl chloride with minor amounts of one monoolefinic or vinyl type of comonomers may be utilized. Illustrative comonomers are vinylidene chloride, vinyl acetate, methyl acrylate, styrene, acrylonitrile, methyl methacrylate, ethylene, propylene and others.

While relatively low molecular weight polyvinyl chlorides are preferred, to minimize the necessity of plasticizer, the present invention is not to be restricted to any relatively critical or narrow molecular weight range. The polymers may be characterized in terms of specific viscosity, intrinsic viscosity or by molecular weights, since all of these are related. The molecular weights normally will vary from about 5,000 to about 50,000 and it is preferred that the approximate average molecular weight be between about 10,000 and 25,000. Intrinsic viscosities will usually vary from about 0.12 to about 0.90. As used herein, the terms specific viscosity and intrinsic viscosity are calculated values derived from viscosity measurements. Solutions for viscometric study are prepared by dissolving 0.125 gram of the polyvinyl chloride in cc. of cyclohexanone while mildly heating and agitating on a solution roller. The solutions are then filtered into an appropriate Ubbelohde viscometer previously calibrated for the pure solvent. The flow time in seconds for the solution is determined at three dilutions to obtain flow data at a number of concentrations. The ratio of the flow time to the flow time of the pure solvent is a value known as the reduced viscosity. When the integer 1 is subtracted from reduced viscosity, one obtains the value known as the specific viscosity. When the specific viscosity is divided by the concentration and the values obtained plotted against concentration, the extrapolation of the resulting straight line to zero concentration gives the value known as intrinsic viscosity. Since the relation between the logarithm of the intrinsic viscosity values and the logarithm of the molecular weights is a straight line function, the approximate molecular weight of any polyvinyl chloride may be readily calculated from its intrinsic viscosity value. Thus, an intrinsic viscosity value of 0.2 corresponds to a molecular weight of approximately 8800 and a value of 1.0 corresponds to a molecular weight of about 58,000. Best foxing adhesion is obtained when the PVC is applied in amounts between about 0.005 and 0.15 gram per square inch of textile so treated.

The polyvinyl chloride may be applied to the fabric, and particularly to the area of the textile upper later to be contacted with the foxing compound by any desired means such as by dipping or spraying in solvent solution, by a cement or as a latex.

One preferred class of resins utilized as tie-coat polymers in the structures of the persent invention may be referred to as acid-cured thermosetting aminotriazinealdehyde resins. These include resins formed between an amino triazine and an aldehyde and treated under acidic conditions and at a time and temperature sufficient to form a water-insoluble cured resin coating. While the triazine may be mixed with a variety of proportions of aldehyde to form prepolymers suitable for acidand heatcuring, it is preferred that l-6 mols of aldehyde be used per mol of aminotriazine.

Suitable triazines include diaminotriazines, triaminotriazines, alkyloldiaminotriazines and alkyldiaminotriazines. Aldehydes such as formaldehyde, propionaldehyde, acetaldehyde, fural and benzaldehyde may be used. Specifically, the preferred resins are formed between melamine (2,4,6-triamino-l,3,S-triazine) and formaldehyde in mol ratios between about 1:1 and 1:3. Any alkyl substituents on the triazine molecule preferably have l-8 carbon atoms.

The resins and their curing systems are known. Curing agents are normally applied to the textile with prepolymers, usually but not necessarily in an aqueous solution. Water or other sovent is evaporated and the resin cured to a water-insoluble state by heating at 300-400" F. for 1-30 minutes. Suitable acid-acting catalysts include, for example, mineral acid, ammonium salts such as ammonium chloride and mineral acid salts of alkaline earth metals such as magnesium chloride. These are present in amounts varying between about 1 and about 50 parts by weight per 100 parts of prepolymer.

The resin may be modified by the presence of pigments, plasticizers and tackifying resins such as the phenol formaldehyde or coumarone-indene resins. The resin on the area to be later contacted with the foxing strip should preferably be present in an amount based on the area being so treated of between about 0.002 and 0.04 gram per square centimeter. The resin may be applied to the textile as a solution, as an aerosol or as an emulsion.

The polychloroprenes utilized as another preferred class of tie-coat polymers, have molecular weights in the order of between about 20,000 and 1,000,000 and to predominate in species having molecular weights between about 50,000 and 250,000. They may be utilized either in an unvulcanized condition or they may be compounded with vulcanizers and accelerators resulting in a vulcanized polychloroprene area. In the latter case heat for vulcanization is supplied by the injection molding process itself; that is, the polychloroprene coating vulcanizes when it is contacted by the hot block polymer foxing compound. Furthermore, it has been found advantageous if the polychloroprene is to be vulcanized to include at least a portion of the vulcanizing agent in the block copolymer foxing compound, thus causing a certain amount of chemical interlinking between the foxing strip and the area of textile treated with polychloroprene. The particularly unexpected feature of the present invention 15 to find that the treatment of the textile with polychloroprene increases the adhesion of the block copolymer foxing strip even under wet conditions and in spite of the fact that these two polymers are so dissimilar chemically.

The vulcanizing agents utilized for the vulcanization of polychloroprene are well known in the art and include especially zinc oxide and preferaby mixtures of 21110 oxide with magnesium oxide, although litharge or red lead may be utilized in place or in addition to these materials. Accelerators may be utilized to promote vulcanization if desired. Advantages of zinc oxide and other nonsulfur-donating vulcanizing agents in this system are that they do not vulcanize the block copolymers herem described. Vulcanization of the block copolymers is not only unnecessary but may be deleterious to physical properties.

EXAMPLE I A cotton canvas laminate was prepared using as the combining composition a vulcanized SBR. The laminate was cut to the shape of temris shoe uppers and the area of the canvas to be contacted with the foxing was sprayed with an aersol of polyvinyl chloride (dissolved in ketones) having an average molecular weight in the order of about 15,000, the aersol medium being Freon. An amount of about 0.04 gram per square inch of polyvinyl chloride was thus deposited in the foxing area of the textile upper. The treated uppers were then fitted into an injection molding shoe manufacturing machine and a block copolymer composition injected into the mold to simultaneously form the soling and the foxing. The composition employed for this purpose was as follows:

Parts by wt.

Polystyrene-polybutadiene-polystyrene block polymer (22,000-45,000-22,000 mol. wt.) 100 Mineral oil 108 Polystyrene 60 TiO 15 Clay 75 The shoes so prepared were subjected to three washing and drying cycles. In the washing operation the shoes were washed with a commercial domestic detergent in a domestic washing machine. In the drying operation the domestic dryer was set at the warm temperature drying level. Essentially no change in the foxing adhesion was noted after this Washing test. Comparable shoes were prepared in which the polyvinyl chloride treatment was omitted, all other conditions of the preparation and assembly being identical. After the same washing and drying cycle, however, it was found that a substantial parting of the foxing from the canvas upper occurred.

One quarter inch Wide samples of the shoe uppers bearing a foxing strip, prepared as described above, were subjected to a soaking test comprising immersion in a 1-2% aqueous laundry detergent solution for 30 minutes at room temperature. Control specimens bearing no tiecoat were compared with specimens bearing 0.01 g. PVC

Peel strength, p.l.i.

Before soak After soak Control, no PVC PVC coated EXAMPLE II Comparative tests were performed on shoe assemblies with and without a polychloroprene treatment. Canvas sheeting was laminated with a cured SBR combining paste to form a canvas laminate which was cut into the form of tennis shoe uppers. The area which was to be contacted with the foxing strip was treated with a solution comprising 60/40 methyl ethyl ketone/normal hexane containing 8% by weight of a polychloroprene having a relatively high viscosity, a fast crystallization rate and light color. The polychloroprene used was of the type which does not contain sulfur linkages or a thiuram disulfide, as do some commercial grades. Impregnation was 0.03 g./in.

The solution also contained suspended 0.75 phr. of accelerator, namely, 2-rnercaptoimidazoline and 4 phr. of magnesium oxide. After evaporation of the solvent the treated canvas uppers were fixed on a shoe molding machine form and a compound designed for both soling and foxing injected into the mold. The injection molding conditions consisted of a polymer melt temperature of about 400 F., injection pressure of 250 p.s.i. (gauge), pressure within the mold of p.s.i. (gauge). Injection time was about 3 seconds and the formed shoe assembly was held in the mold for approximately one additional minute to allow the thermoplastic rubber compound to become firm through cooling. The compound used for this latter purpose comprised parts by weight of a block copolymer, parts by weight of a naphthenic mineral rubber extending oil, 30 parts by weight of crystal polystyrene, 85 parts by weight of an inorganic filler, namely, clay and titanium dioxide mixture, and 1 part by weight of antioxidant. The formulation also contained 25 parts by weight of the zinc oxide which acted as a curing agent for the polychloroprene.

In order to test the effectiveness of the polychloroprene treatment, a parallel test shoe assembly was prepared utilizing all of the same conditions and components with the exception of the polychloroprene treatment and the zinc oxide component of the soling and foxing compound. The resulting shoes were tested in the Instron tester under both wet and dry conditions. The shoe assembly having the polychloroprene treatment had wet and dry peel strengths of 14 pounds per linear inch. Contrasted to this, the shoe assembly in which the polychloroprene treatment was omitted had a dry peel strength of 15 p.l.i. while its wet peel strength was only 9.0 p.l.i.

The block copolymer used in both shoe assemblies had the structure polystyrene-polybutadiene-polystyrene, the block molecular weights being 23,00041,00023,000.

EXAMPLE HI Tests were performed to determine the effect of varying the type of solvent by which the polychloroprene was applied to the canvas uppers insofar as wet peel strength of the block copolymer foxing was concerned. At the same time further comparative tests were made to determine the effect of polychloroprene treatment of the convas versus no treatment since there was a change in the foxing formulation from that described in Example I. For the present tests, the same canvas laminate was utilized cut into the shape of tennis shoe uppers. Comparative samples were treated with polychloroprene, one by means of a chloroform solution and the other by means of a methyl ethyl ketone/hexane solution. The block copolymer compound described more fully hereinafter was utilized for injection molding of a soling and foxing onto these treated uppers. The wet peel strength of the foxing was found to be 27 pounds per linear inch for the shoe assembly treated with polychloroprene in chloroform solution and compared with pounds per linear inch for the shoe assembly in which the canvas was treated with polychloroprene in methyl ethyl ketone/hexane solution. The comparable shoe assembly was prepared in which the foxing and soling was molded onto the convas uppers in the absence of any prior treatment with polychloroprene. The wet peel strength in this instance was only 6 p.l.i.

The block copolymer formulation utilized for soling and foxing was as follows:

Parts by wt. Block copolymer 100 Naphthenic mineral rubber extending oil 110 Crystal grade polystyrene 60 Mineral filler 90 Zinc oxide, when used Antioxidant 1 EXAMPLE IV Tests were performed to determine the wet and dry peel strengths of shoe assemblies with and without a polychloroprene treatment as in Example 11 except that the polychloroprene solution contained 5 phr. of suspended zinc oxide in addition to 0.75 phr. Z-mercaptoimidazoline and 4 phr. of magnesium oxide, and the foxing compound used contained no zinc oxide. In this case a wet peel strength of p.l.i. was obtained for the shoe assembly having the polychloroprene treatment, compared to 7 p.l.i. for the untreated shoes. Dry peel strengths were 13 p.l.i. for the treated foxing and 11 p.l.i. for the untreated foxing.

EXAMPLE V Tests were performed to determine the wet and dry peel strengths of shoe assemblies with and Without polychloroprene treatment after laundering and drying the fabricated shoes in a household automatic washer and dryer through two separate cycles. The polychloroprene treatment and foxing compounds were essentially the same as those in Example 11. The wet and dry peel strengths of polychloroprene-treated shoe assemblies were 16 and 15 p.l.i., respectively, while those of nontreated shoes were 6 and 5 p.l.i., respectively, after two complete cycles of washing and drying.

EXAMPLE VII Comparative tests were performed on shoe assemblies with and without a resin treatment. Canvas sheeting was laminated with a cured SBR combining paste to form a canvas laminate which was cut into the form of tennis shoe uppers. The area which was to be contacted with the foxing strip was treated with a melaine-formaldehyde prepolymer in aqueous solution (1040% w.).

The solution also contained 3.5% by weight of ammonium chloride and 26% of magnesium chloride based on the weight of preploymer. After evaporation of the water the treated canvas uppers were heated for 3 minutes at 350-375 F. to cure the resin and then were fixed on a shoe molding machine form and a compound designed for both soling and foxing injected into the mold. The injection molding conditions consisted of a polymer melt temperature of about 400 F., injection pressure of 250 p.s.i. (gauge), pressure within the mold of p.s.i. (gauge). Injection time was about 3 seconds and the formed shoe assembly was held in the mold for approximately one additional minute to allow the thermoplastic rubber compound to become firm through cooling. The compound used for this latter purpose comprised parts by weight of a block copolymer, 108 parts by weight of a naphthenic mineral rubber extending oil, 60 parts by weight of crystal polystyrene, 90 parts by weight of an inorganic filler, namely, clay and titanium dioxide mixture, and 1 part by weight of antioxidant.

In order to test the effectiveness of the melamineformaldehyde treatment, a parallel test shoe assembly was prepared utilizing all of the same conditions and components with the exception of the melamine-formaldehyde treatment. From the resulting shoes one-half inch strips cut from the foxing area were tested in the Instron tester at 0.2 inch per minute grip separation rate under both wet and dry conditions. The shoe assembly having the treatment had a dry peel strength of ll-14 pounds per linear inch and a wet peel strength 10-12 p.l.i. Contrasted to this, the shoe assembly in which the melamine-formaldehyde treatment was omitted had a dry peel strength of 11 p.l.i. while its wet peel strength was only 7 p.l.i.

The block copolymer used in both shoe assemblies had the structure polystyrene-polybutadiene-polystyrene, the block molecular weights being 23,00041,00023,000.

EXAMPLE VIII The extent of foxing separation of shoes treated according to the present invention were compared with shoes which did not have the tie-coat treatment, referred to below as control samples. Testing was by means of actual wear tests for the periods indicated in the following table:

Foxing separation area ratio variable} control Maximum depth of foxing separation tie coat (el Weeks on test variable control The uppers utilized in the shoes tested were canvas duck. The soling and foxing composition in samples A-D was that described in Example I. The soling and foxing composition in samples E and F was altered in that the polystyrene content was reduced to 30 parts by weight, other components being present in the proportions specified in Example 1. PVC refers to polyvinyl chloride.

We claim as our invention:

1. In a footwear assembly comprising a textile upper, a polymeric soling and a foxing, the improvement comprising a polymer tie coating on at least the area of the upper which is covered by the foxing, said foxing com prising a block copolymer having the general configuration selected from the group consisting of wherein each A is a polymer block of a monovinyl arene, B is a polymer block of a conjugated diene, and n is a whole interger between 1 and 5, the tie-coating polymer having a tensile strength of at least pounds per square inch and a dielectric constant at least equal to that of the block copolymer, the wet peel strength at 23 C. of the textile-tie coat-foxing assembly being at least about 70% of the dry peel strength of said assembly at 23 C.

2. An assembly according to claim 1 wherein the tiecoat polymer is at least one polymer of the group consisting of polymers of vinyl halides, amine-aldehyde copolymers, phenolics, phenol-aldehyde copolymers, halohydrocarbon polymers, epoxy resins, cellulose ethers, and esters, ABS polymers, polyurethanes, acrylate polymers, methacrylate polymers, the area of foxing separation during 1 1 1 2 Wear tests of shoes is reduced by a factor of at least two References Cited compared with control shoes bearing no foxin tie coat. UNITED STATES PATENTS 3. An assembly according to claim 1 Wherein the block 145 487 8/1 6 copolymer has the structure polystyrcne-polybutadiene- 25 3 3 5532:;

2g t ir zsembly according to claim 3 wherein the textile 5 3293494 12/1966 Fischer 3,373,150 3/1968 Pears et al 26092.8

is a cellulose-based textile.

5. An assembly according to claim 4 wherein the tiecoat polymer is a polymer of vinylidene chloride. PATRICK LAWSON Pnmary Exammer