CA1069425A - Artificial leather and method of manufacture - Google Patents

Abstract

Abstract of the Disclosure A process for making an artificial leather sheet material which comprised providing a sheet of microporous preformed elastomeric polyurethane material having on one of its faces a second thermoplastic elastomeric polyurethane of lower melting point than said first mentioned polyurethane, said second polyurethane having a hot tacky adhesive surface and pressing the hot tacky adhesive surface against the surface of a permeable fabric of inter-laced multi-fiber yarns. The material is, for instance, suitable for making shoe uppers.

Description

This invention relates to a laminating process and to a laminateO
According to the present invention a process for making an artifi- -cial leather sheet mateTial comprises providing a sheet of microporous pre-formed elastomeric polyurethane material having on one of its faces a second thermoplastic elastomeric polyurethane of lower melting point than said first polyurethane having a hot tacky adhesive surface and pressing the hot tacky adhesive surface against the surface of a permeable fabric of interlaced multi-fiber yarns. The preformed polyurethane layer is preferably maintained in ad-herent, bu~ strippable, relationship with a dimensionally stable support whilst the hot tacky adhesive surface is provided and whilst the tacky adhesive surface is pressed agains~ the surface of the permeable fabric of interlaced multi-fiber yarns.
The ~acky adhesive surface may be provided by applying to a surface of the preformed sheet an adhesive comprised of thermoplastic elastomeric polyurethane of lower melting point than the polyurethane of the microporous polyurethane, drying to remove any solvent present and then heating it to render it tacky.
Alternatively, the hot tacky adhesive surface may be provided by a hot melt adhesive.
The density of the sheet of preformed polyurethane material is pre-ferably at least 0.3 g/cm3 e.g. in the range 0.3 to 0.4 g/cm3.
The other face of the fabric may have a nap of fibers teased from -the said yarns and bonded together, the bonded nap having a void volume of above 50%.
The fabric may be a woven fabric, and may comprise cellulosic fibers or thermoplastic organic polymeric fibers. Preferably the interlaced yarn structure of the fabric has a d~ape stiffness of less than 2.25 inches.
The microporous polyurethane layer may have a continuous substan-tially non-porous skin at its upper surface.
The continuous microporous elastomeric polyurethane layer pTefer-ably has a thickness of 0.3 to 0.8 mm.

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The bonded nap preferably comprises the said teased-out fibers and an elastomeric bonding agent therefor. The bulk specific gravity of the bond-ing agent in the nap zone preferably is at most about 0.5. The interlaced fabric structure preferably is substantially free of bonding agent but the said bonding agent is in contact with surfaces of the multi-fiber yarns at the base of said nap. The thickness of the said bonded nap may be 0.1 to 1 mm, e.g. 0.1 to 0.7 m~.
In one form of the invention there is a continuous microporous elastomeric polyurethane layer on the upper face of the said fabric and a thin continuous substantially non-porous skin on the upper surface of said poly-urethane layer, and the combined thickness of said microporous layer and said skin is 0.2 to 1.5 mml The specific gravity of the said microporous layer preferably is less than o.6 and the specific gravity of the said skin is at leastl~0'~9. The sa~d yarns preferably are twisted staple fiber yarns, the total weight of fibers in the said interlaced fabric and the nap thereof preferably is at least 200 ~m and the said fibers preferably are largely thermoplastic staple fibers and the fibers of said nap preferably comprise staple fibers -which may have both their ends buried within a twisted yarn of said fabric and have their intermediate portions in said nap~ The said intermediate portions of fibers having both ends buried with a twisted yarn preferably constitute the major fiber content of the said napO The said thermoplastic staple fibers may be largely polyeth~lene terephthalate or stereoregular polypropylene and the said total weight is in the range of 200 to 300 g/m .
In another preferred form of the in~ention the said bonded nap com-prises the said teased-out fibers and an elastomeric bonding agent therefor~
~nd the said bonding agent is present as webs joining individual fibers of the nap, the said webs being so thin that the out1;nes of indi~ld~al nap fibers are visible, the said bonded nap bein~ Dpen, compressible and having the feel of a -fabric surface and having a void volume above 50%. Alte ~atively the said

-2-bonded nap may comprise the said teased-out fibers and an elastomeric bonding agent therefor and the said bonding agent may be present as nodules deposited from a dispersion of particles of the said agent.
In a preferred form of the invention the bonding of the said nap fibers is such as to have no substantial effect on the breathability of the product, the said nap is less than 1 mm thick~ is unsheared~ has fibers longer than 2 nml, has 1000 to 3000 nap fibers per square inch and substantial com-ponents lying generally paraIlel to the main plane of the ~abric~ the said void volume is about 70~ the napped fabric is a woven fabric which, as such and without bonding of the nap~ has a trouser tear strength of at least 7 pounds in both warp and weft direction and an elongation at break of at least 10% and a module is at 5% elongation of 5 to 30 lbO/in.~ the said fabric being woven in a pattern having repeating lengths of yarn spinning at least two trans-verse yarns.
The invention also extends to a process for making artificîal leather sheet material which comprises proYiding a fabric having an interlaced structure of multi-fiber~ preferably twisted, yarnsg teasing rom yarns of the said fabric a nap of fibers anchored within said twisted yarns~ bonding together fibers of said nap, the bonding of the nap being such that the bonded nap has a void volume of above 50%~ providing a sheet of microporous prefo~med elasto-meric polyurethane material3 having on one of its faces a second thermoplastic elastomeric polyurethane of lower melting point than said first mentioned poly-urethane~ providing a hot tacky adhesive surface on said second polyurethane and pressing the hot tacky adhesive surface against the surface of the fabric remote from the bonded nap.
The said bonding of the nap may be effected after the application of the said polymer layer, or before the application of the said polymer layer~
The said bonding may comprise applying to said nap an elastomeric bonding agent.
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Thus in one form of the process the said bonding comprises applying to the said nap a solution of an elastomeric bonding agent without substantial impregnation of the interlaced yarn structure of the said fabric, and removing ~ -liquid from the said solution to set the said bonding agent while maintairling said nap in such an open condition that the void volume of the bonded nap is at least 50~.
In another form of the process the said bonding comprises applying to the said nap a dispersion of particles of an elastomeric bonding agent in a liquid~ e.g. an aqueous latex, and removing liquid from the said dispersion to set the said bonding agent while maintaining the said nap in such an open con-dition that the void volume of the bonded nap is at least 50%.
The invention also extends to a lasted shoe upper made from an arti-ficial leather material in accordance with the invention. The layer of per-meable fabric made of interlaced m~ti-fiber yarns preferably has a flat upper -faceO The interlaced yarn structure of said fabric preferably has a drape stiffness of less than 2-1/4 inches and preferably at least 1-1~4 inches.
A skin of film forming flexible polymeric material, may be formed on the upper face of said microporous polyurethane layer, and may have a thick~
ness of up to 70 microns and a density of at least 1 g/cm3.
The invention also extends to a lasted shoe upper made from a material in accordance with the invention Certain suitable shoe upper materials produced making use of the process of this invention are illustrated in the accompanying drawings in which:Figures 1 to 8~ 129 15 and 16 are photomicrographs of cross-sections.
Figure 9 is a photomicrograph of a face of a fabric layer after the fabric has been stripped from the structure shown in Figures 1-8.
Figures 10 and 11 respectively are photomicrographs of each face of the fabric used to make the structures shown in Flgures 1-8.
Figure 13 is a photomicrograph of the napped impregnate~ face of the

-4-~G~4~5 fabric used to make the structure shown in Figure 12.
Figure 14 is a photomicrograph of the napped face of another fabric.
Figure 17 is a photomicrograph of the napped7 impregnated face of the fabric structure sho~n in Figures 15 and 16.
Figures 1-5~ 12~æ3 were made with a scanning electron microscope, as described~ for instance~ in United States Patent 33637,41S (Civardi) column

5 line 71 to column 6 line 18.
Figures 6 to 8~ 10~ and 11~ were made with an ordinary light microscope.
In the embodiment illustrated in Figures 1~ 2, 5-11 there is a layer of woven fabric 11~ a layer of microporous elastomeric material 12, an elasto-meric adhesive 13 bonding the lower face of the microporous layer to the upper face of the fabric and a skin 14 of film-forming polymeric material on the upper face of the microporous layer. It will be seen that the adhesive 13 is in contact with the upper surface of the fabric and that the fabric is sub-stantially non-impregnated by the adhesiveO
More specifically~ in the structure shown in Figure 1 the woven fabric is made up of multi-fiber yarns or threads running substantially transversely to each other (i.e. warp and weft threads~. In Figure 1 the cross-sections of the yarns 21~ 22, 239~24~ 25, running in a direction transverse to the plane of the picture, are evident; groups of fibers of other yarns (e.g. yarn 27) running paraIlel to the plane of the picture are also seenO Figure 6 shows, i more clearly~ a warp yarn running parallel to the plane of the picture and the cross-sections of five weft yarns (running in a direction transverse to the picture~. In Figure 7 (a cross-section in a plane at right angl~es to that of Figure 6) a weft yarn runs parallel to the plane of the picture and the cross-sections of se~eral warp yarns are also evident.
Each ~arn is made up of a number of fibers ~in this case the fibers are cotton staple fibers) arranged substantially parallel to each other and in _5~
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cohering relationships. In the fabrics shown in the drawings the cohering relationship of the fibers results from the fact that they are twisted to-gether.
The fabric in Figure l is an unnapped cotton sateen having its "sateen face~' (characterized by exposed lengths of warp yarns spanning several weft yarns) uppermost and in contact with the adhesive. There are 96 warp yarns per inch (i.e. 38 per cm) and 64 weft yarns per inch (i.e. 25 per cm~.
The weaYe pattern is 5 harness 4/l satin weavc; thus each of the exposed len~ths of warp yarns at the upper face spans four weft yarns as can be seen in Figure lOg while on the opposite face (Figure ll) there are exposed lengths oP weft yarn each spanning four warp yarns. The warp yarns have a count of 18.5 and a Z-twist of 4~21 turns per inch and the weft yarns have a count of 12.5 and~a Z-twist of 3.78. ("Count" is cotton count, referring to the number of 840-yard hanks per pound). The fabric has an elongation at break of about 10% in the warp direction and about 15% in the weft direction (measured before lamination).
Its thickness is about 0.5 mm.
As indicated~ the sateen fabric in Eigure l has a Plat (i.e. sub-stantially un-napped) face in contact with the adhesive Like practicall~ all fabrics made of s-taple fiber yarns~ it does have isolated individual Piber ends projecting from each face, but the number of such fibers is small~ well below about 2000 per square inch of face (iOe. below about 300 per square cm.) gener-ally below about 1500 per in (iOe. below about 250 per cm ~, and the project-ing fibers are of uneven exposed lengthO
As seen in Figure 1 the adhesive deposit is quite thin~ In the struc-ture shown in Figure l the distance between the top of the yarn 23 and the bot-tom o~ the microporous layer 12 is well below 0.05 mm9 e.g. of the order of 0.01 ~-to 0.02 mm7 and that between the yarns the adhesive deposit on the bottom sur.
face of the microporous layer may be just as thin~ or even non-existent In the structure shown in Figure 1 although the adhesive in that embodiment is -':

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moulded to confo~l to the upper portions of the yarns and extends down along the sides of those upper portions it did not fill the spaces between the yarns to any significant extent. Thus, in the structure shown in ~igure 1 the voids 31, 32 between the yarns are largely free of a~lesive (the total of the thick-ness of the downwardly extending adhesive fingers 36, 37 is considerably less than 1/4 of the shortest distance between the yarns 2~ 23~. This is borne out in the structure shown in Figure 6 (in which the space 38 between the very uppermost portions 39y 40 of the warp yarn 41 is largely free of adhesive) and in Figure 7 ~which indicates spaces 42 largely free of adhesive above the tops of most of the visible warp yarn cross-sections~. Figure 7 also indicates that the weft yarn makes very little contact with the adhesive layer; at the centre of Figure 7 there appears to be a finger of adhesive 43 extending downward in-toadhesive contact with the uppermost portion 44 of the weft yarn. This is con-firmed in Figure 6 in which there is an open space between the adhesive layer and the top of the visible weft yarn 46 that lies over the warp yarn.
Figures I and 5 also indicate that there is no significant penetration of the adhesive into the individual yarns; apparently the spaces between adja-cent fibers ~of the bundle of fibers making up each yarn) are so smaIl that the adhesive comes into contact (and bridges) only those fibers which happen to be outermo~t (and uppermost) at the zone where the adhesive contacts the yarns.
It will also be understood, that because of the twist in the yarns and the length of the fibers, a given fiber will be in contact with the adhesive (at the outer upper surface of a yarn) for only a portion of the length of that fiber, and generaIly for only a ~inor portion of its length; for the remainder of its length that fiber will be located within the yarn away from its surface;
or situated at another surface of the yarn~ or situa~ed in that length of yarn which is buried~ and not at the upper face of the fabric. (Staple fibers are typically over 2 cm long and thus would generaIly extend over several repeated "buried" portions of the yarn; continuous fibers are of practically infinite .;

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length)~
Figures 1 and 5 indicate that very little, if any, of the adhesive serves to bond yarns directly together~ although~ of course~ it does serve to -bond all or part of the yarns together indirectly, by bonding them individually to the microporous layer; thus the adhesive does not markedly stiffen the fabric as would be the case~ if it bonded adjacent yarns directly to each other, Some of the adhesive may adhere to portions of the yarns that are spaced from the adhesive layer on the microporous layer 12 and such adhesive may be present, and bridgeg some yarn cross-over points 100~ as indicated at the left of Figure 8.
The strength of the bond between the fabric and the microporous layer is about 8 to 12 pounds per inch or more (Instron testerg A5TM~D 751~68)r ~hen the fabric is stripped mechanically from the rest of the laminate ~as by grasp-ing an exposed edge of the fabric and peeling off the fabric), the adhesive re-mains substantially on the microporous layer and the stripped fabric is largely or substantially free of the adhesive and retains substantially its original pliability~ ~igure ~ indicates that some adhesive may remain on the very top surface of the yarns of the fabric la~ter stripping.
In Figure 1 the structure of the microporous layer 12 is substantially the same as that of the microporous layer ~hown in Civardi United States 3~637~415 at Figures 1 and 3 and at the lower right of Figure 4 of that patent.
The said layer (and its method of manufacture) is described in the specification ~-of that patent ~particularly the ~'less dense upper layer" of its Example 23. ~ -The layer is about 0.020 inch ~i.e. about Q.5 mm) thick9 its density is about 0.35 g/cm3~ and its tensile strength is in the range of about 7 to 10 pounds ~;
per inch of width and its elongatlon at break is in the range of about 150 to 250~. It is substantially isotropic ~e.g. the ratio of the modulus ~at 10%
elongation) in any two longitudinal directions at right angles to each other is within the range of about 0.75~1 to 1~25 1)o It is of substantially uniform ~ S~t~ J~n u ~ d~ J9 ~

- . .. . .~.. ,. -density throughout its thickness and is of substantially unifo~m thickness.
It is composed of a thermoplastic elastomeric polyurethane~ soluble in di-methyl formamide of the type described in Civardi United ~tates 3,637,415 column 4 line 1 to column 5 line 47. In this particular embodiment the micro-porous layer has a tensile set ~measured as described below, after 100~ elon-gation) of above 10% (e.g. in the range of about 10~30% such as about 20%) one minute after the release of stress above 5% (e.g in the range of about 5-15%, such as about 10%) one hour after the release of stress; thus in one measurement the following tenstile set values were obtained for the times, after the release of the stress~ given in parenthesis: 27% (10 seconds after the release of the stress); 20.8% (1 minute); 19.8% (2 minutes), 17.7% (5 min-utes), 14.6% (10 minutes); 12~5% (30 minutes3, 11.5% (60 minutes after release of the stress).
The measurement of tensile set may be made on a specimen of the micro-porous layer, prior to laminating, as follows: a specimen 3/4 inch wide and .3:~ - :
about 6 inches long is marked with bench marks 3 inches apart. The specimen is stretched in an Instron tester so that the bench marks become 6 inches apart ~100% elongation) in a period of 15 seconds. The specimen is then held at 100% elongation for 10 minutes. Shortly upon release ~about 10 sec. thereafter) the distance between marks is measured and the measurement is repeated at pre-determined time intervals while the sample is maintained in an unstressed con-dition. The entire test is carried out at 22 C and 60-65% R.H. It will be understood that percent set is calculated by subtracting the original distance between bench marks ~i.e. 3 inches from the measured distance at the predeter-mined time after release of stress~ dividing the resulting figure by the orig-inal distance (i.e. 3 inches) and multiplying by 100 to get the result in per-cent.
In the material shown in Figure 1 the skin 14 is a relatively dense ; layer of polyurethane h~ving little or no porosity visible at 1000 magnifica _9_ tion, as can be scen from Figure 2. Its density is well above o.6 g/cm . It has a thickness less than 20 microns, e g. about 10 microns; the surface of the skin has a grain texture resembling that o~ le~ther, with small hills and vaIleys~ and the thickness of the skin is thus non~uniform. Th0 whitish por-tion 48 shows the surface of the skin (rather than its cross-section) as ~iewed at a low angle.
The laminates of this invention have given excellent results when tested for use as ~h0 shoe upper material in shoe-making trials with both men~s and womenls shoes. They are soft and comfortable in use and show an e~cellent fine leather-like break~ In the shoe-making process, they have been found to be easy to aut into the desired sh~pes of the individual shoe parts (such as the vamp and quarter of the woman~s cement shoe) with standard ma~hinery, such as a USM clicker using a wooden cutting block~ They stitch well and are lasted readily, using conventional lasting pressures and tensions and conventional steaming o~ the upper and can be heat set in conventional manner to obtain good shoe-shape retention (e.g. above 50%, generally above 60%, retention)~ The lower edges of the lasted uppers can be cemented readily to the shoe bottoms by ~ conventional techniques; one such technique involves roughing to remove all or -~ part of the skin layer from the portion to be cemented and then cementing with -conventional polyureth~ne shoe cement; another such technique involves string lasting and injection molding a thermoplastic shoe sole (of, say, vinyl resin or polyurethane commonly used for that purpose) direc$1y into bonding contact with the unroughened surface of the skin. The shoes show excellent shape and shape r~tention and general appearance and are soft to the touch.
A structure of the type illustrated in Figure 1 has shown the follow-ing properties: Taber Wear Index (OCC-T-1916-Method 5306, H-22 Wheel~ 1000 gm load) first sign of wear occurs at 130 cycles, weight loss at 1000 cycles is 267 mg; Grock(AATCC Method 8-1961 at 100 double strokes) 4 dry, 5 wet; Wyzen-beek Abrasion (CFFA0 2b, with Stainless Ste~l screen, 2 lb. pressure, 6 lb.

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-10- , , s tension 25,000 cycles), passed in both directions (i.e. machine direction, "MD", which is lengthwise of the laminate, and cross machine direction~ "XMD"~
which is transverse to the machine direction); Adhesion ~o~ fabric layer) lb./in. ~ASTM D-751-68 1 in. strip~ 12 in./min.) 10.0 MD, 9.5 XMD; Satra Fexl ~0 C~ 18,000/hr) passed even after 40 hours; Tear, tongue~ lb (~STM D-751-68 12 in./min.) 5.5 ~ 8.4 X~D; Tensile, Grab~ lb., (ASTM D-2208-64~ 121 MD~
107 XMD, 210 diagonal; Elongation ~ (~STM D-2208-64) 26.6 MD, 11.0 XMD, 62.6 Diagonal; Blocking (CTTA-5, 2 in.x2 in. sample 150 F with 1 lb.wt., 30 min.)~
No. l; Grain Retention ~10 min. ~ 260 F), pass; Water Vapor Transmission (Honeywell MYT tester ASTM E-96-66 Procedure) 25.5 gm/m hr; pliability (Tinius Olsen 1 in. sample width, 1/2 in. span, .o80 wt. moment with readings taken at 30 angle of deflection with the skin uppermost and therefore being under com-pression in this test) 36 MD~ 27.5 XMD. The structure also has excellent strength and stability on the bias. ;-~
The structure shown in Figure 3 is substantially the same as that shown in Figure 1 except that there is a difference in the nature and thickness of the skin. The water vapor transmission of this product is lower than that shown in Figure 1 and its flex life is lower. It has higher abrasion resis-tance. More details of the fabrlc construction are evident in Figure 3 because ~ -of the position at which the particular cross-section was made. Figure 3 also indicates an occasional projecting fiber 62 extending upwards from yarn 63 into the adhesive 64; similar projecting fibers are also seen in Figures 5 and

6~ Incidentally, the difference in the ~ppearance of the microporous layer 66 in Figure 3 is believed to be due to distortions owing to the method of cutting the sample. The skin layer is shown at 67 in Figure 4 and its grained textured surface is indicated by the lighter portion at 68.
Another aspect of this inve~tion relates to a process for making a ~ ;
laminate of the type described above. In one particularly suitable technique7 the skin is formed, wholly or in part~ by eoating a solution of the skin ~9~

material onto the surface of a temporary support (such as release paper) which i3 of such nature as to permit subsequent stripping mechanically therefrom without damage to the skin. While the coating is in a tack condition~ a ~icro-porous sheet is placed in contact with it and bonded to it and solvent is re_ moved from the skin layer; thereafter the adhesive is depositedon the free surface of the microporous sheet, the fabric is placed in contact with the ad~
hesive, and the resulting laminate is stripped from the suppork. The support may have a smooth glossy surface, giving the product a "patent leather~ Pinish.
The support may also have a textured surface~ simulating a selected leather grain, for example; this texture is imparted to the sldn and is exposed on stripping.
In the technique described above~ in which a solution of the skin material (or a portion thereof) is first applied to a temporary support, the water vapor permeability of the skin ~and thus of the entire product) may be ~-increased by first wetting the contacting surface of the ~icroporous sheet with a coagulant for said solution e.g. a material (such as water) which is miscible with the solvent of the solution (e.g. dimethylformamide) and which is a non-solYent for the dissolved skin material (e.g.poly~rethane). The product shown in Figures 1 and 2 is made by this technique, while that shown in Figures 3 and ~0 4 is made without the use of a coagl~ant. The coagulant is preferably one which is substantially inert to the material of the microporous layer and does not degrade its structure under the conaitions~employed in the process.
According to ~ preferred form of the present invention the process involves applying the fabric to a tacky adhesive on the surface of the thin elastomeric microporous layer while the la~ter is maintained in adherent, but strippable~ relationship w~ith a dimensionally stable backing,such as the re-lease paper. By this procedure impregnation or penetration of the adhesive into the interstices of the ~abric is dim~ish~d~and stiffening of the fabric is thereby reduced or avoided; also there is less tendency for surface roughening - - ~ - , . ~ - ~ :
.. , or fabric show-through during stretching in the lasting operation. The presence of the dimensionally stable backing contributes to this and tv the production of a uniform attractive product, inhibiting deformation of the thin low density elastomeric microporous layer during the laminating processO Other dimensionally stable backings may be employed instead of the release paper.
Thus a rigid temporary backing may be used. For example~ the microporous thermoplastic polyurethane layer tends to soften and adhere to a hot metal (e g. carbon steel) surface (e.g. having a temperature of about 145-165 C);
the microporous polyurethane sheet may be fed continuously into contact with a rotating hot metal roll so that one face of the microporous sheet adheres to the surface of the rollgthe adhesive may be applied to the other face of the sheet and~ when the adhesive has reached a tacky condition and while the sheet is still on the roll; the fabric may be fed continuously into contact with the tacky adhesive, after which~the assembly ~of fabric-adhesive-microporous layer3 may be stripped off the roll.
The adhesive is preferably a thermoplastic and elastomeric poly-; urethane. Adhesives of this type are commercially available. Thus one may employ one of the well known ~two package" adhesives comprlsing a polymer hav-ing terminal hydroxyl groups such as a pol~ester or polyether as one component, and a polyisocyanate reactive with those hydroxyl groups as the other component~
the components being mixed just before use and reacting to form a high molecular weight elastomeric cross-linked polyurethane in situ. One or both of the com-ponents is usually supplied in solution in an inert volatile solvent (e.g. ethyl acetate or acetone) and the reaction may be accelerated by adding a catalyst for the reaction~ as le well known in the art. The solvents employed generally also act as swelling agents for the microporous layer; thus if the solvent-containing adhesive is applied, in the same amount as used in the process of this invention~ to the thin microporous sheet the latter swells and distorts extensi~ely (even thoughithe linear polyurethane of the microporous sheet is 1~3694~5 insoluble in the swelling solvent), but when the microporous sheet is first bonded to the release paper or other solvent-resistant backing such distortion ~ ' does not occur~ the distorting tendency resulting from the swelling being re-sisted by the releasable bond between the backing and the microporous sheet.
The solvent-containing adhesives generally contain an amount o~ ~sol~
vent such that the adhesive flows readily during its application to the micro~
porous layer, It is preferable to remove some of the solvent(as~by evaporation) to decrease the flowability of the adhesive and increase its tack before the Eabric is pressed against the adhesive, so that the adhesive is brought to a ' stage in which the laminating pressure acts to mold the adhesive into firm contact with the adjacent outer yarn surfaces without causing penetration and , P
consequent stiffening of the fabric layer. The laminating presswre may be exerted in any desired manner; conveniently the assemblage of fabric; micro-porous layer and release paper is passed through the nip between a hard-sur-faced (e.g. metal),roll and a roll having a more yielding surface (e.g. a rubber-covered roll) so that the laminating pressure is exerted substantially ~uniformly across the area of the assemblage. Thereafter any remaining solvent ; may be removed and curing (i.e. reaction to higher molecular weight) of the adhesive can be effected. Usually the release paper is not stripped off until' the adhesive has been at least partially cured to a stage at which the forces exerted in the stripping operation will not substantially affect the adhesive bonding between the fabric and the microporous layer~
The appearance of the adhesive in~the structures shown in Figures 1, 3~ 5 and 8 indicates that the momentarily exerted laminating pressure resulting from the passage of the assemblage through the nip of the pair of rolls ~-squeezes (and deforms) both the fabric layer and the microporous layer so that portions of its yarns near the upper surface of the fabric are pressed momen~
tarily against the adhesive layer and that thereafter the fabric and microporous layer tend to recover to their undeformed condition that said yarn portions --1~-- , retract, relatively, carrying with them some of *he adhesive, removing it from the layer on the microporous material, leaving substantial voids between this fabric-carried adhesive and said adhesive layer. These voids are generally not closed cells; they communicate ~ith the numerous air passages through the fabric. Such removal of adhesive reduces the effective thickness of said layer and increases its capacity for transmitting moisture vapor.
For small scale, or laboratory operation, the tackiness of the ad-hesive just prior -to exertion of the laminating pressure may be easily control-led by a simp~e fiber test, in which one permits the sol~ent to evaporate from the adhesive layer and then places one's finger lightly on the surface of the adhesive and then draws the finger away, excellent results have been obtained if laminating is effected immediately after the finger is found to stick firmly to the layer (being "grabbed" thereby~ so that the finger drawn away only by exertion of some force ~like that encountered when applying the same test to the adhesive surface of conventional Scotch brand transparent pressure sensi-tive tape~. In large scale practice, the conditions of evaporation prior to passage through the nip can be accurately controlle~d, as by passing the mate-rial, directly after application of the adhesive and while the adhesive-coated material is travelling to the nip, through a suitable housing provided with 20 an evaporative atmosphere having a controlled rate of flow, composition and ; -temperature. At the start of operation the initial settings for control of the evaporative atmosphere may be made readily by trial-and-error ~such as by the use of the finger test or by microscopic inspection of the final product, - followed by appropriate adjustment of the evaporation conditions), e.g~ increase the evaporation ~as by increased temperature or longer time~ if the adhesive is stringy just prior to laminating, allowing the finger to be pulled away easily, and decrease the evaporation if the adhesive no longer sticks to the finger.
It will be understood that in the pre~erred embodiment the lamination occurs - under substantial pressure such as to mold the adhesive~ this is a pres-. ~
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sure considerably greater than is present when there is light contact, i.e.
greater than so-called "kiss pressure".
The release paper may be one of the known commercial types, which are coated papers whose coating contains a release agent such as a silicone. The adhesion between the release paper and the microporous layer should be such that the forces induced by the swelling of the microporous layer (owing to the effect of the solvent-containing adhesive, as di~cussed) do not cause separa-tions between the release paper and the microporous layer. This adhesive depends, for instance~ on the character of the coating of the release paper (e.g release paper having a heavier coating, free of discontinuities~ gives less adhesion) and on the time and temperature of treatment during removal of solvent of the skin layer of the laminate. The optimum conditions can be determined readily by routine trial~and-error following the teachings herein.
Thus for the embodiment (described previously) in which a coagulant-bearing ~e.g.pre~wet) microporous sheet is used, the effect of the presence of the coagulant is to decrease the tendency of the skin layer to adhere to the re-lease paper; in that embodiment we have found that it is best to use a more lightly coated paper having more discontinuities in its coating~ such as a release paper that is customarily used as a temporary backer for hightly vis-cous vinyl plastisols, i.e a paper well known in the trade as "vinyl paper"
(e.g. the product known as "Transkote FERI' made by S. Do ~arren Co division of Scott Paper Co~)0 Such vinyl paper is genera~ly not employed in the art as a release paper for polyurethane solutions since the latter conventionally tend to become so strongly bonded thereto that, on stripping, portions of the release paper or of the polyurethane deposit tend to be pulled off. It is also within the broader scope of this inrention to use backers which carry~less release agent than vinyl paper, in the embodiment in which coagulant is present3 par-ticularly when appropriate adjustment is made in the conditions of removal of solvent from the skin layer.

Trademark ~9~

In an e~bodiment in which a pre-wet microporous sheet is employed, the pre-wetting may be effected by saturating the thin sheet with water and then pressing it to remove most, or s~lbstantia-ly all, of the water that can be removed by mechanical expression For instance~ the sheet may be placed loose in a vessel containing a dilute solution of a surf~ctant (e.g. in less than about 0.1% concentration~ such as 0.01 to 0.05% of Aerosol 0~) in warm water taken up approaches the saturation value (for ~he microporous sheet shown in Figures 1-3 the saturation value is above 150% of water based on the original~
unsoaked, weight of the sheet). Th0 wet sheet is then passed through the nip between a rubber roll and a steel roll which are urged together under relatively high pressure, e.g. 30-60 pounds per lineal inch of nip, the sheet then has a water content of about 80 to 100% (again, based on the original weight of the unsoaked sheet). Such a sheet may then be applied to the solvent-containing skin layer on the release paper, as described. In the procedure just described the coagulant (water) is present in the interior of the microporous sheet as ~
well as in its surface zones. We have found that excellent results are also `
. ~:
obtained when *he coagulant is present inonly the surface zone to be placed in contact with the solvent-containing solution. For instance, a surfactant- con-*aining solution may be applied to the upper surface of the sheet (the sheet ~
20 being in substantially flat~ horizsntal condition) and allowed to penetrate r; ~ ' thereinto for a short time (as low as 10 seconds for instance)~ after which the excess unabsorbed water may be removed as by a squeegee, givi~g a water content (again based on the original weight of the sheet) of more than about 5%, e.gO
about 10 to 60%, the water-treated surface of the sheet may then be laminated continuously to the solvent-containing skin layer. The optimum water content depends to some extent on the properties of the microporous sheet, such as its -~
rate of water absorption3 and may be determined by routine trial-and-error with . . .
the teachings of this application in mind.

particularly preferred product made by the process of this invention Trademark -17- ;

- - . - .. -is a laminate comprising (a) a fabric having a flat upper face, a drape stiff-ness of less than 2-1/4 inches, preferably less than 2 inches (Cantilever test 30 angle~ ASTM D-1388-64~ a thickness of 0.3 to o.8 mmg e~g. 0.4 to o.6 mm~
such as about 0.5 mm, a grab tensile strength of above 75 pounds (A~TM D-1682-64); (b) a layer of microporous elastomeric polyurethane having a density in the range of 0.3 to 0.4 g/cm3~ a water vapor permeability of at least 150 g/m2/
hr (ASTM E-96-66), a cohesive strength of at least 12 lbs. (and more preferably at least 20 lbs) per inch of width, (cohesive strength is measured by strongly adhering each face of the layer to a strong flexible supporting fabric, as by means ofanadhesive which does not damage the structure of the layer and then pulling the adjacent ends of the supporting layers apart at a speed of, say, 12 inches per m~nute in a suitable physical testing apparatus, such as a Scott or Tinius Olsen tester) and a thickness of 0.4 to 0.5 mm; (c) an elastomeric ad-hesive bonding the lower face of said microporous layer to the upper face of a said fabric, said adhesive being in contact with the upper surface of said fab-ric, and said fabric being substantially non-impregnated by said adhesive, and (d) a skin of film-forming flexible polymeric material~ on the upper face of said microporous layer, having a thickness of up to 70 microns, preferably 10 to 50 microns, and a density of at least 1 gram per cm3. Products having thin~-ner skins show a finer~ more subtle 3~break'l but generally do not have as high aresistance to abrasion; thus a product having a skin thickness of say about 7 microns is more suitable for use as an upholstery material (i.e. as the outer surface of upholstered furniture) than as a shoe upper material. ~ graph of the density gradient across the thickness of one preferred type of laminate, ~-starting with the skin layer3 shows a density above 1 g/cm3 (e.g. in the range of about I to 1.4) for a distance substantially equal to the thickness of the skin, then a relatively constant density of 0.3 to 0.4 g/cm3 for a longer dis-tance, substantially equal to the thickness of the microporous layer~ and then a density averaging roughly 0~2 to 0.4 g/cm3 for a distance corresponding sub-- ~ .

~C96~S

stantially to the thickness of the fabric.
In the product illustrated in Figures 1 - 3 the fabric layer is of cotton sateen. It will beunderstood that other fabrics may be used. Such fabrics may be made of yarns or threads of staple fibers, such as cotton, poly-ester ~e.g~ polyethylene terephthalate), nylon (e.g. nylon-6- or nylon-66) or blends thereof (e.g. 50/50, 25/75 or 75/25 blends such as of cotton and poly-ester~ or of continuous filaments ~e.g. polyester or nylon~. The fabric may be of the woven type or the knitted type~ In either case the fabric should have an elongation at break of at least 5%~ preferably at least 7% in each direction. For example the elongation at break of the illustrated cotton sateen fabric (before laminatio~ is about 15~ (in the weft direction~ and x 10% (in the warp direction), while the elongations at break for the polyester-cotton fabrics -illustrated herein are over 20% ¦e.g. 30 or 40%) in each direction~ In the most preferred form of the invention the yarns of the fabric are substantially unimpregnated and substantially free of sizing. In any event, the type and - degree of sizing or other non-fibrous material is not such as to raise the , .. ,. ,::
stiffness of the interlaced yarn s*ructure of the fabric to more than 2-1/4 inches (Cantilever test, ASTM-1388-64). The fabric has at least one flat (i e.
; substantially unnapped~face~ which is in contact with the adhesive. The other face may be flat or napped. The use of napped fabrics constitutes an especially preferred aspect of the i~vention and ~ill be described at a later point in this ;~
s~ecification~
- The microporous layer is preferably substantially isotropic as pre-viously indicated; it is, however, within the scope of the invention to use anisotroplo layers.
The polyurethane material of which the microporous layer is composed is preferably of the type described in Civardi United States 3~637,415 column 4 line 1 to column 5 line 47 CyclDaliphatic or aliphatic diisocyanates may be used as all or part of the diisocyanate content, and the proportion of diiso-.;

;9~5 cyanate may be such as to give a nitrogen content of say 3.5 or 3.8, for instance.
It is within the scope of the invention to use microporous poly-urethane lc~yers whose cavities are of smaller or larger size than those shown in Figures 1 to 4o~!Civardi United States 3~637~415. Such products may be made, for instance, by using water-soluble salt particles of smaller or larger size in the polyurethane-solvent salt-paste the coagulation of which produces the microporous layer. Alternatively the microporous layer may be produced ~ by the techni~ues described in Civardi United States Patent 3,590,112 at col-10umn 3~ lines 29 to column 4 line 11. Preferably a cross-section of the micro-porous material shows numerous voids, at least 1 micron in diameterg occupying more than 50% of the area of the cross-section.
It is preferred that the microporous layer be of substantially uni- -form density throughout its thickness. It is, however, within the scope of the invention to use a microporous layer having two or more sub-layers of differ-ent density. For example, one may, less preferably, use a sheet obtained by slicing the unfinished two~layer sheet described as the starting material of Example 2 of United States 3,637,415 integraIly attached to about 0.1 mm of the adherent denser layer; if the resulting sheet is then employed in the pro-duction of the laminate of this invention, with the denser layer of the mi¢ro-porous sheet facing the fabric, the laminate will be somewhat stiffer than when the microporous sheet has ~he same total thickness but is~ uniforml~ a single layer of said less dense structure. The same "slice" may be used in the laminate with its denser layer adjacent to the skin (gi~ing improved abrasion resistance to the product and modifying its break). It will also be understood that the processes of this invention may also be used with more dense microporous elastomeric layers, e.g~ layers having densities of about 0.5, oO6 or 0~7 g/cm3 or with microporous materials which are cross-linked and not the~moplastic and which show much lower tensile set values.

A~ /r~v~ ~ Jlrn~ ~7, Iq7 J
--20~

In the s~ cture of the product illustrated in Figures 1, 3$ 5 and 8 the adhesive layer is substantially continuous, but the bonds to the fabric are spaced apart~ with portions of the adhesive layer between these spaced bonding areas being out of contact with the fabric and not contributing substantially to the adhesion; the adhesive ma~erial a&eres ~trongly to the microporous polyurethane, and the portions between the spaced bonding areas are unnecessa~y for providing the adhesion between the microporous polyurethane and the fabric.
It is within the scope of this invention to use a discontinuous adhesive, as by intaglio printing a pattern of spaced dots of adhesive onto the face of the microporous sheet (and then, while the adhesive is in active condition, bring-ing the fabric into contact with that face). me distance between the tops of the yarns at the flat face of the fabric and the bottom of the microporous - layer is preferably less than 0.1 mm and more preferably well below 0.05 mm.
It is within the scope of this invention to produce the laminate with-out employing a temporary backer. In such case it is preferable to apply the adhesive in a fo~m substantially free of solvent having a swelling action on the microporous sheet. Thus one may employ a hot melt polyurethane adhesire applied hot to the microporous sheet, the fabric may be laminated to the hot adhesiveg either immediately or after the latter has been cooled somewhat to increase its tack. It will be understood that the microporous sheet need not carry a skin layer at the stage at which it is attached to the fabric.
When the skin layer is not present on the microporous sheet~ it may be applied to the microporous sheet fabric composite by known techniques, such as by using the surface finishing treatments described in Civardi United States Patent 3~637~415 or in Civardi and ~uentsler Canadian Patent No. 948,498 dated June 4, 1974 or in HuIl United ~tates Patent 3,689,629.
The skin layer may receive additional finishing treatments. For example the skin may be built on to the skin side (e.g. by spraying) after stripping off any temporary backer which may have been used for instance mate~

~21-., ,- , . . . , -s rial to give an "aniline" or tone-or-tone effect ( as described in Canadian Patent No. 948,498), may be applied as by spraying or by roller (e.g. an in-taglio roller~ having very small closely spaced depressions for carrying the coating material to the surface to be coatedl. Designs may 'be applied by prin~ting~ e.g. with a pigmented solution of an elastomeric polyurethane~ Also the skin layer may 'be modified by heat treatment, with or without pressing, as by hot embossing (by which the microporous layer may also be permanently de-formed in desired pattern) or ~by a smoothing contact with a hot surface.
Other finishing tr~atments such as those described in United States Patents 3,481,767 and 3,501,326 may be used.
The laminate may be hot boarded or "milled" to produce a material having the wrinkled fine grain appearance of milled leather. For instance the laminate (after stripping off any backer used) ~ay be heated in an oven at, say, about 150 C and then, while still hot, it may be doubled over, with its skin surface inside, and pressure may be exerted at and near the fold line while the fold line is moved back and forth along the length of the material and while chan~ ng the fold so that the movément occurs along various fold lines so as to cover the whole area of the piece.
As mentioned above, the bottom face of the fabric may be napped and the napped fibers may be then bonded together. For example, a fabric may be napped on one face, in conventional fashion as by passing itin contact with moving napping elements such as bristles or hooks (such as a high speed counter rotating wheel having such napping elements projectîng therefrom to raise or tease out fibers from its yarns). In the case of a woven fabric moving in the warp direction and subjected to oppositely moving elements~ the nap fibers will originate mainly from the weft yarns which run transversely to the direction of movement of the napping elements~ particularly when the face being napped has a preponderance of exposed weft yarns. The resulting nap is preferably a mass of fibers which lie in all directions~ and ha~ing substantial components lying 3L~6~ z~
generally parallel to the main plain of the fabric. Usually the nap includes a significant proportion of fibers whose ends are not visible at the napped surface such as fibers whose both ends are buried within a yarn and whose inter-mediate portions arch through the nap zone. It should be noted that conven-tional staple fibers are generally at least 2 cm in length~ and t~us much lon-ger than the expused length of a yarn at the surface of the fabric (which ex-posed length is generally less than about lmm). Thus if the napping elements pull a length of even 1~ ~ or 5 mm of a given fiber from an exposed yarn, one or both ends of that fiber will still be anchored in, and twisted with~ the other fibers of that yarn. Less preferably, the nap may be sheared in conven-tional fashion~ for example~ so as to cut any fïbers which may have been raised (e.g. at right angles to the plane of the fabric) to s~ch an extent as to pro-ject significantly from the main nap ~one. ~igure 14 is a plain view of the face of a napped and sheared fabric (specifically a 4/1 sateen weighing about - 8.5 ounces per square yard (290 g/m ) and composed of yarns of a blend of 75%
- polyester (i.e. polyethylene terephthalate) and 25~ cotton with 60 filling yarns per inch and 60 warp yarns per inch~ napped on the face having a prepon-derance of filling~yarns~. The extent of napping is preferably such that a sub-stantial~ but generally minor~ proportion of the weight of the fibers i9 brought into the nap zone, for example about 1/2 to 1 ounce or more of fiber per square yard in the nap for a fabric weighing about 6 to 9 ounces per square yard. Generally the weigh~ proportion of the fibers brough~ into the nap zone is above 1% such as about 2 or 5 to 20%~ preferably in the range of about 2 10 or 1~%, of the total weight of the fabric (the nap fibers generally are an-- chored in, and teased from the weft yarns and accordingly~ for fabricsin which the weight of weft yarns is about equal-to the weight of the warp yarns3 the weight proportion of the weft yarns in the nap is 2 or 10 to 40%~ such as about 4 to 30%, e.g. about 10 to 20%. It is preferably not such as to weaken the fabric, by removal of fibers from its main load carrying zone7 that its strength ~and thus the strength of the laminate) will be below the level needed for the intended purpose.
The face of the fabric to be napped may be given an abrading treat-ment, e.g. with sandpaper, before napping, to sever some fibers at the exposed surfaces of the yarns.
The bonding of the nap fibers may be effected in various ways. In one preferred embodiment bonding is effected while substantially maintaining the nap in its open, low density state. For instanceg the nap may be impreg-nated with a latex~ such as a flexible acrylate polymer (e.g. polymerized ethyl acrylate or copolymers thereof) before or after lamination~ taking care to avoid or minimize impregnation of the main fabric structure composed of interlaced multi~fiber yarns. A product of this type is illustrated in Figures 12 and 13~ in which the fabric is a 4/1 sateen weighing about 6.5 ounces per square yard (220 g/m ) and composed of yarns of a blend of 75~ polyethylene terephthalate and 25% co*ton, with 44 weft yarns per inch and 80 warp yarns per inch~ the weft yarns having more fiber than-the warp yarns~ napped on the face having a preponderance of weft yarns~ having its nap impregnated (prior to lamination) as ~ith a latex of a flexible acrylate polymer followed by evaporation of water from the latex, the amount of polymer being only a minor proportion (e.g. 5%) of the total weight of the fabric. In the structures shown in Figure 13 (compare Figure 14) the deposited polymer bridges and bonds together nap fibers at spaced zones (e.g. 71, 72) along their lengths~ and also forms occasional nodules thereon. The use of an aqueous ]atex is espe-cially suitable when the nap comprises a high proportion (e.g. at least 50~) of highly water-absorbent fibers~ such as cellulose fibers. The latex may be of a conventional elastomer such as diene homopolymer or copolymer~ e.g., rubber butadiene-acrylonitrile copolymer which may be cross-linked as by vul-canization after impregnation. For other fibers, such as polyester fibers, it is often more desirable to apply the bonding agent in solution in volatile or-ganic solvent, although either technique may be employed for either or both -" 30 types of fibers. Typically the amount of bonding agent is within the range of ~06~

about 5 to 2~% or moret e.g. 50 or 60% of the total ~eight of the fiber of the fabric~ depending on the proportion of the fabric in the nap and the thickness of the nap, the weight ratio of bonding agent to fiber in the nap may be, say~ about 0.4:1~ 1 1, 2:1~ 5:1~ 10:1 or 20:1.
Another way of bonding the nap fibers is by applying a thin layer of polymer to the surface of the nap. Figures 15 to 17 illustrate one such embodi-men~, in which the fabric is a 4/1 sateen weighing about 6.5 ounces per square (220 g/m 3 and composed of yarns of a blend of 75 % polyethylene terephthalate and 25% cotton~ with 44 weft yarns per inch and 80 warp yarns per inch, the wcft yarns having more fiber than the warp yarns, napped on the face having a preponderance of weft yarns~ to which a layer of a solution of two-component cross-linking elastomeric polyurethane was applied to the nap (afterlaminationj) by knife-coating followed by evaporation of the solvent and curing by heat, the '! ~:
amount of polyurethane so deposited being about lOg per m Prior to thistreat-ment of the nap the measured thickness of the laminate was about 1.0 mm, while after the treatment it was about 1.2 mm (as measured with a standard gauge~used for measuring the thickness of leather, e.g. an Ames gauge, which exerts a Gom- -pressing force on the sheet whose thickness is being measured); thus~thé^th-i`cl~
ness of the nap ~one is over 0.2 mm. Other methods of bonding the individual nap fibers together at spaced points will be apparent to those skilled in the art. Thus it is within the scope of the invention to effect such bonding by suitable heating and/or solvent treatment, to tackify at least some of the nap fibers, and to bring them together7 if necessary, to cause bonding.
It is also within the scope of the invention to carry out allor part of the napping after t~he application of the b~nding agent and before the setting thereofO For instance7 one may apply (as by spraying~ to the bottom face of the fabric~ a latex ~e.g. an acrylic latex such as water-diluted Phoplex HA-8 conta;n;ng about 5% of tha dispersed polymer and some 95% of water)~ and there-after subject said bottom fact to a conventional napping operation before ~or Trademark -25- ~
~ ,: -:

~L~3t~ h~ 5 when) the water has evaporated sufficiently to make the resinous binder sticky, thereafter the napped fabric may be passed through a drier to evaporate the water and set the binder.
The bonding of the nap fibers and the formation of the porous layer on the flat face of the fabric may be carried out in a single continuous oper-ation. For example, a coagulable solution of an elastomeric ~aterial may be used ~or impregnating the nap and then a coagulable elastomer mixture to form a substantial microporous layer may be applied to the flat face of ~he fabric, after which ~he whole assemblage may be coagulated by application of a non-solvent medium~ such as ~ater. Preferably the nap-impregnant is a solution in a watcr-miscible high boiling solvent and the coagulable microporous layer- -~
forming mixture is a solution, in the same solvent, which has been made into a paste by inclusion of dispersed removable fiIler, such as a water soluble salt, the paste being applied in such thickness as to produce a layer which (after coagulation in water and drying~ is, say~ about 0.3 to 1 mm thick; then, while widthwise shrinkage of the fabric is prevented by carrying the fabric on a tenter frame to maintain it at substantially constant width during the sub-sequent processing~ the whole asse~blage may be passed into an aqueous coagu- -lating bath and then leached (eOg. in water) to remove th~ filler,then dried and annealed (e.g. at about lSO~C)~ Thereafter a finish coat may be applied.
A particularly suitable solvent for the nap-impregnating solution and the paste composition is dimethylformamide (IIDMFI'). The solutions and micropore-forming ;
pastes thereof are k~own in the art; see for instance, United States Patent 3,590,112, particularlyg the "upper layer paste'l thereof. To pro~ide a softer product one m~y use a polyurethane made with a lesser amo~nt of diisocyanate such a~ ~ give a polyurethane whose nitrogen content is, say, about 3 to 4%g e~g. 3.2 or 3~5% N. ~inishes to be applied to the upper surface of the micro- ~
porous layer are also known in the art; see for instance, United States Patents - ~-3,590,112, 3,6379415 and 3,764~363.

.

s The napping and bonding treatment makes it possible to produce, simply and at a relatively low cost, a poromeric structure highly suitable for shoe uppers which has high strength, a soft desirable hand and good shoe making properties including resistance to show-through on lasting~ good skiv-ing, anti-fraying, and folding characteristics, and also has a bottom face having the appearance of a non-woven Pabric, without the need for providing a non-woven or without the need for any of the operations~ such as intensive needle-punching, heavy impregnation~ splitting and buffing~ characteristic of manufacture of non-wovens for use in leather substitute. See the article by L. G. Hole3 Satra, on "Poromerics: their structure and usel' in Rubber Journal April 1970 p. 72, 73~ 75, 76, 809 81, 83.
As indicated above, the laminate made from the napped bonded fabric has good skiving and folding characteristics. Skiving generally involves cut-ting with a mechanically operated knife (see Figure 28) in a controlled manner to thin the sheet so that the thinned por*ion can be folded on itself and held in folding position (with interposed adhesive~ forming an edge of substantially the same thickness as the main body of the sheet. During the skiving the knife is guided in a direction roughly parallel to the sheet for a substantial por-tion of its travel through the sheet. With the napped bonded laminate of this invention the skiving knife may readily cut through or pass just below, the interlaced yarn portion of the fabric, leaving at least portions of the inter-laced yarn structure adhered to, and stabilizing, the microporous layer at the thinnest portion of the skived zone (as in a shoulder scarf, or a groove scar~), permitting formation of smooth stable, strong fold without the need for inser-tion of an adhered reinforcing tape at the inside of the fold. The napped bon_ :, ded construction makes it possible to control the skiYing and to avoid the marked tendency for the direction of the cut to be deflected upvards or down-wards of the plane of the interlaced fabric which occurs when con~entional fabrics are used.

:
' ~OG~

While the reasons for the greatly improved skivability of the mater-ials of this invention are not clearly understood, it is believed that the bonding together of the nap fibers acts to stabilize and reinforce the fabric structure so that when the knife edge is pressed against the fabric the yarns do not tend to move away~ relatively, from the knife edge or be displaced from their previous positions by the pressure of the knife, causing deflection of the direction of the cut. Some bonding of surface portions of the yarns to each other and/or to nap fibers may also contribute to this effect. It is noteworthy that even when the latter bonding to yarn surfaces takes place, as when a nap impregnating binder is employed, the presence of the nap tends to prevent substantial filling of the spaces or hollows present at or near yarn intersections (see Figures 18 and 21) and the structure is no~ stiffened ap-preciably~ certainly not to the extent that is observed when the same binder is applied to the surface of the same fabric before napping.
Products made from the napped bonded fabric have also been found to be outstanding in their shoe-making characteristics other than the good skiv-ing and folding characteristics discussed above. They aktain a very high com-bined score when rated on their behavior in the ~ollowing operations of signif-icance in shoe making: cutting (with relatively blunt leather dies), stitching I ~ -component adhesion (using conventional latex adhesives, e.g. to adhere stifr;feners or ~plumpers~ lasting (conformability), roughening (such as resistance to "orange-peël" formation onlasting, and ability to produce a reall~ smooth patent surface)? and roughing ~in preparation for sole attachment). They are so highly resistant to f~aying on wear that they may be used in unlined shoes without special protection of the cut edges of the material. Fraying charac-teristics may ba tested in the following manner- the material is die-cut to form a 3 inch diameter circle or a 2x4 inch rectangle~and 8 to 16 such pieces are placed in a smooth surfaced cylindrical container having an internal volume of one gallon and an internal diameter of 7-7/8 inches ~e.g a labora-~28-tory ball mill of 1 ga. capacity) along with a 5 inch long by 2 inch rectan-gular piece of pine having rounded edges; the container is then rotated on its -axis at 78 rpm for a period of up to 24 hours at room temperature. Typical samples of the product resist sho~ing any fraying~ visible to the naked eye~
even after test periods well over 4 hours~ such as 12 or 24 hours. In pre-ferred products the degree of napping is such as to substantially obscure the ~mderlying fabric weave pattern; the fraying test described above may also be used to test the wear-resistance of this effect. Thus, if the nap-bonding treatment is omitted the fabric weave pattern will usually become evident in the fore~oing test before the 24 hour test period is over while the bonded nap will still have its weave-obscuring effect. See Figures 24 (unbonded nap before test), 25 (unbonded nap, after 24 hours test~, 26, (bonded nap before test) andi27 (bonded nap after 24 hours test)a which are views looking down onto the nap with an ordinary light microscope, the product being that of Example 20 below, in the same test the product having the bonded nap shows no "pilling" even though it contains pilling-susceptible polyester fibers, while the product having the unbonded nap shows marked pilling when examined after four hours of test.
It is preferred that the fabric be tightly woven (or tightly knitted) so that there are at least about 3000 yarn cross-overs per square inch (thu the 60x60 woven fabric previously described has about 3,600 yarn cross-overs per square inch, while the described 80x40 woven fabric has about 3,200 yarn cross-overs per square inch)~ The thickness of the nap is preferably within the range of about 0.1 to 0.5 mm or 1 mm such as about 0.2 to 0.4~ .5a o.6 or 0 7 mm and the weight of fiber in the nap is preferably within the ranges of about 0.1 to 0.3 to 1 ounce per square yard, such as about 0.2~ 0~3 or 0~5 oz. `
per square yard. As indicatedt each yal~ preferablr is made u~o~aiplluralit~ of substantially parallel f-ibers (generally well over 10~ such as 50 or more;
the number of fibers can be counted in the illustrated cross-sections) and the --2g--yarns are preferably twisted, e.g. to well over one turn per inch~ such as 2 to 5 turns per inch. Best results have been obtained to date with woven fabrics which have at their smooth face repeating~ numerous exposed lengths of yarn which span two or more transverse yarns~ e.g. satin or sateen weaves.
It is, ho~ever, ~ithin the scope of the invention to us0 square weaves (e.g.
sheeting3~ drills or twills.
Napping often increases the number of cross-overs~ as by removing portions of weft yarns so that widthwise shrinkage occurs (see Example 18 below~ in which the mlmber of cross-overs of the fabric increases by about 10% as a result of the napping). Preferably the fabric is so constructed that after napping it has a trouser tear strength (ASTM 751-68T~ of about 5 pounds, and still more preferably at least about 7 pounds such as 7 to 9 or 10 pounds~
and an elongation at break of at least 10% such as 15 to 20% or more. It is also preferable that it have a modulus at 5~ elongation (~STM D-2208) in the range of about 5 to 30 lb/in., that it be sufficiently resilient to recover substantially completely from an elongation, by stretching, of about 2% pre-ferably even from an elongation of about ~% ~in the warp or filling direction).
The fabric, particularly when it contains thermoplastic fibers~ is preferably given a heat-setting treatment to stabilize its configuration at the highest temperature to be encountered in the laminating process, e.g. a heat-setting treatment (while the dimensions of the fabric are maintained con-stant~ on a tenter frame) at a temperature about 30 C above said highest tem-perature, such as a temperature of about 235 C for a fabric which is to be vinyl coated in a process using a plastisol-fusing temperature of 205 C. This heat-setting may be effected before or~ preferably~ after napping and may if desired be effected after, or coincident with~ the nap-bonding treatment~ such as during the curing or setting of the nap~bonding agent~ -As previousl~ indicated~ the fabric may contain such fibers as cotton, ~;
polyester or nylon Other fibers such as rayon, àcrylic, (e.g. polyacryloni-~I~Gg42S
trile), or polyolefin (e.g. isotactic polypropylene) may also be employed alone or in blends of two or more types of fibers. Certain fabrics tend to shrink considerably when exposed to elevated temperatures, e.g. 140 C (such as are used in some of the Examples, below) for set~ing the adhesive or the nap bonding agent. With such fabrics, e.g. of polypropylene fibers one can employ known adhesives and bonding agentscwhich are suitable for use at lower temperatures such as those which set quickly to a strong condition on simple evaporation of solvent or diluent, or those which contain sufficient cata~yst to cure in a short time at a relatively low temperature; or one can allow a longer time for curing to occur with the particular disclosed agents, e.g.
one can pass the assemblage through an oven at a temperature at which the sub-stantial shrinkage does not occur ¦such as 55 or 60 to 70DC.) to evaporate any solvent or diluent and then allow full curing to occur on storage for a few days.
The following Examples are given to ~llustrate the invention further. ~ -Example 3 is a specific embodiment of the process of the invention. Examples ~ -1 and 2 and 4 to 1~ illustrate in detail the structure and composition of the various layers which may be adhered to each other by the process of the in- -~
vention which is shown in Example 3. In the Examples all pressures are atmos~
pheric unless otherwise indicated. In the application all proportions and percentages are by weight unless otherwise indicated.
Example 1 A pigmented 15~ solution of thermoplastic elastomeric polyurethane in a solvent mixture of 55% N,N-dimethylformamide ("DMF"3 and 45% acetone is deposited (by knife coating) at a wet thickness of 3 to 4 mils~(0.075-0~1 mm) on a sheet of embossed release paper. The polyurethane is of the type describe-d in Example 1 of United States Patent 3~63?,415 and the amount of pigment (e.g.
Superba~ carbon black~ is about 20% of the amount of polyurethane in the solu-tion. The deposited layer is exposed to the atmosphere to permit evaporation #Trademark . . .
-. - . ~ . . .. : . . .

9~Z~

of some of the solvent for about 30 seconds~ so that it has a tacky surface, and is then laminated to a self-sustaining thin sheet of microporous elasto-meric polyurethane 0.5 mm thick and of specific gravity of about 0.35 ~cm3 (which is soluble in DMF) by passing the coated release paper and the micro-porous sheet through a nip (of a steel roll and a rubber-covered roll) with the microporous sheet in contact with the coating using light pressure (e.g.
about 1 pound per lineal inch of nip) and applying as little tension as pos-sible to the microporous sheet. The assemblage is then heated in an oven for one minu$e at 290-320F ~about 140-160 C). This removes the solvent and bonds the coating firmly to the paper. The heating may be carried out in two successive ovens, one at 250-280 F; the second at 290-320 F. A solvent-con- -taining curable elastomeric adhesive is then applied to the free surface of the microporous sheet and a portion of the solvent is allowed to evaporate in the atmosphere for 1 minute to decrease the flowability of the adhesive and increase its tack. Directly thereafter the adhesive coated material is lamin-ated to a sheet of cotton sateen fabric (un-napped sateen weighing 250 g. per square m~lter ~i.e., 1.21 60 inch yards per pound) and having a thickness of about 0.5 mm). Lamination is effected by passing the material through a nip (of a steel roll and a rubber-covered roll~ with the fabric in contact with the adhesive coating, using a pressure (e.g. 3 to 10 pounds per lineal inch) such that the adhesive layer is molded into firm adhesive contact with the surfaces of the upper portions of the exposed yarns.
The resulting laminate is then heated in a circulating hot air oven at 280-320 F for a time su-fficient to substantially remove all the solYent from the adhesive ~e.g. for 1 to 5 minutes), and to partially cure the adhesive. ~ ;
The release paper is then mechanicall~ stripped from the laminate while winding the laminate into roll form with its fabric layer facing outward, and the laminate is allowed to stand in the atnosphere for a t~ne sufficient for the adhesive to cure substantially completely, (e.g. for 72 hours~.

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The microporous sheet is produced by cutting off the upper layer of a two-layer sheet of the type illustrated in United States Patent 3~637,415.
A single layer sheet of the same type may be produced in the manner described in Canadian Patent 86S,oo8. The residual salt content of the microporous sheet is below 0.2%.
The curable adhesive is a commercial two component system, whose components are mixed just prior to use, the mixture is applied to the micro-porous layer in any suitable manner, as by knife coating at a wet thickness of about 0.1 mm. One component is 100 parts of a 30% solution in a 60% acetone/
40% D~ blend of Impranil Cg a hydrox~l-terminated pDlyester, while the other component is 5 parts o~ a 75% solution of ethyl acetate of Imprafix TH, a pre-polymer having terminal isocyanate groups (a polyfunctional adduct of toluene diiosyanate and a polyol). When mixed and allowed to cure it forms a cross-linked elastomeric polyurethane, curing may be accelerated by including a catalyst ~such as 1-5 parts of Imprafix BE) in the mix~ure and/or by heating.
If the same solvent-containing adhesive is epplied to the same micro-porous sheet as ~uch, not bonded to a backing, the sheet swells and distorts extensively.
Details of the Impranil-Imprafix 5ystem are given in the article by Glen7~ and Kassack in Tinctoria Vol. 59 (1962) pages 245-249. Another two-component system, of the same type, is a mixture of Witco Chemicalls Witcobond 202 and Witcobond XB.
Example 2 Example 1 is repeated except that one face of the microporous sheet is pretreated with water so that (when that ~ace is brought into laminating contact with the coated release paper) the microporous shcet carries about 0 30~ of water (based on the weight of the polyurethane), the release paper is S.D. Warren Companyls l'Transkote FERI~ which is a "vinyl paper"~ and the time in the oven (directly after the assemblage of coated release paper and wet Trademark .. . . - . :: :
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65~4Z~i microporous shee~ pass through the nip) is extended (e.g. to 1-1/2 - 2 minutes) to fully evaporate the water therefrom prior tothe application of the adhesive.
The resulting product has a much better water vapor transmission than the product of Example 1. Its WVT is about 27 g/m /hr. as compared to about 8-10 g/m /hr for the product of Example 1. The WVT of the structure at an intermediate stage prior to the application of the adhesive (i.e. as measured on a structure produced by stripping off the release paper before any adhesive is applied to the free, microporous, side) is about 45 g/m /hr as compared to 11-13 g/m /hr for the corresponding intermediate structure of Example 1. ' ' The prewetting of the microporous sheet is effected by applying to the upper face of the sheet (in flat, horizon*al' condition) water, at a temperature of about 40 to 60 C) ~say 50 C~ containing about 0.005-0.01% of Aerosol~ OT (a surfactant, sodi~lm salt of dioctyl sulfosuccinate) allowing the watsr to soak into the sheet for 10-30 seconds (e.gO 20 seconds) and squeegeeing off surface moisture directly thereafter.
E~ample 3 Examples 1 and 2 are repeated except that as the adhcsive there is ''' e~ployed a thermoplastic elastomeric polyurethane (such as Estane"~'5701) of lower melting point than the polyurethane of the microporous layer~ the ad~
hesive being applied as a 25% solution in 50/50 acetone/DM~`. The solvent is removed by evaporation and heat is applied to the adhesive layer to raise its temperature above its softening point and make it tacky (e.g. to a temperature of about 135-170 C) and the fabric is then inmaediately brought into contact with the tacky adhesive and the asserablage passed through the nip as described '~;
in ~xamples 1 and 2.
Examp_e 4 Example 1 is repeated using as the release paper ~c D~ Warren Co.
~ans~ Patent AV; Hi calf grain, a polyurethane casting paper. After the ~Trademark , . . . . . -. - : . - , : -. . :

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adhesive has fully cured a two-packRge clear elastomeric cross-linked poly-urethane coating is applied to the exposed surface of the skin by dip coating or reverse roll coating to produce a high gloss patent leather type of finish.
The amount of coating material applied is such as to produce a clear top coat 15 to 30 microns in thickness on drying and curing. The formulation of the clear coating is a mixture of Permuthane~ 20-249-lO0 and Permuthane~
V5822-70 in 0.7:1 ratio, diluted with 25-35~ solids with methyl ethyl ketone.
Example 5 Examples 1 and 2 are repeated and after the adhesive has fully cured ~here is applied to the exposed surface of the skin, a top coat of an elasto-meric polyurethane having a higher modulus than that of the polyurethane of the skin. The top coat may be applied by gravure prin*ing a lS% solution of Permuthane U lO-011 in 50/50 toluene methyl CeIlosolve~ and then heating in an oven at 160 C for a~short time (e.g. l to l-1/2 minutes~ to evaporate the solvent, the coating being applied in such amount as to deposit about 3 to 5 grams of polyurethane per square meter.
Exa~ple 6 Example 1 i5 repeated, except that the Impranil~ C is supplied in a solution free of DM~, the solvent being a mixture o~ 80% acetone (which evapo-rates rapidly) and 20% methyl Cellosolve~ acetate (which evaporates more slowly)and is still present in the adhesive layer when the desired tack is attained by evaporation Both of these are swelling agents for the microporous layer.
Example 7 -~
Exa~lple 6 is repeated except that the 6.~ ounce per yard (220 g/m 3 . ~ .
fabric having a lightly impregnated nap shown in ~igure 13 is used in place of the cotton sateen.

Example 8 Example 6 is repeated except that the unimpregnated napped 8~S oz.

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per square yd. 1290 g/m ) fabric shown in Figure l4 is used in place of the cotton sateen.
Example 9 Example 6 is repeated except that the napped 8.5 oz. per square yd (290 g/m2) fabric used in Example 9 is used in place of the cotton sateen.
Thereafter the nap is knife-coated with about l0 g (solids basis3 per square meter of a two-component solvent-containing polyurethane adhesive blend similar to the adhesive described in Example 7 but employing a softer polyurethane (specifically a m-ixture of: l00 parts of a 30% solution, in 80/20 acetone/
methyl Cellosolve acetate~ of Impranil~ CaW3 a hydroxyl-terminate polyester, 5 parts Imprafix~ TH, and 5 parts Imprafix~ B~) and then heated for 2 minutes at 150 degrees C after which the adhesive layer and nap coating or bonding agent are allowed to cure fully, while the material is at rest, for say 72 hours at room temperature The resulting st~cture is shown in Figures 15 to 17, Figures lS
and 16 are cross-sections, Figure 16 showing a cross-section in a plane at ri~htangles to that of Eigure 15; and Figure 17 is view of the bottom (impregnated) face of the fabricO I* will be seen that the structure is similar to that shown in Figures l~ 2, 5-ll in that there is a layer of woven fabric llA, a layer of microporous elastomeric material 12g an elastomeric adhesive 13 bond- -ing the lower face of the microporous layer to the upper face of the fabric and a skin l4 of film-forming polymeric material on the upper face of the micro-porous layer, the adhesive 13 being in contact with the upper surface of the ~ ;
fabric and the fabric being substantially non-impregnated by the adhesive.
Figure lS shows a warp yarn'(ronning parallel to the plane of the pic~ure) and the cross-sections o~ a total of five weft yarns (running in a direction trans~
verse to the picture)O In Figure 16 a weft yarn runs parallel to the p~ane of the picture and the cross sections of some ten warp yarns are also evident.
The adhesiTe deposit is guite thin~ like that seen in Figure l described . ' ' Trademark .. . ... . . .

earlier3 and its character is like that described earlier in connection with Figures 1, 6 and 7. Thus the space between the very uppermost positions of the warp yarn seen in Figure 15 is largely free of adhesiveg and the uppermost portion of weft yarn (seen to the right of Figure 15) makes very little con-tact with the adhesive layer, there being fingers of adhesive extending down into adhesive contact with said uppermost portion of the weft yarn, probably as a result of the retraction of the layers immediately on release of the laminating pressure and consequent exertion of tension on the adhesive layer to pull adhesi~e fingers therefrom, leaving open~celled voids between the adhesive on the microporous layer and the top of the fabric and thinning out lor removing portions of3 the a &esive layer on the microporous layer. (Figure 16 may give a false impression, at first glance, that there are some indi~idual fibers extending upward into the microporous layer; these fibers are, of course, stray fibers, resulting from the sectioning operation, which happen to have been moved, after sectioning, into positions in front of the plane of the cross-section).
Unlike the structure shown in Figures 1, 29 5-11 the fabric has a substantial low-density nap layer 81 extending down from the interlaced yarn structure, in this case the nap layer has a thickness comparable to that of ;~
the interlaced yarn structure. The elastomeric bonding agent or impregnant has, in this case, not penetrated to the interlaced yarns; see the thin webs of impregnant 82 which join and bridge neighboring fibers but do not form a con-tinuous pore-free layerg there being large impregnant-free spaces 83 between many of the fibers. -~
Examples 10 and 11 Examples 7 and 8 are repeated, except that in each case the fabric -has 60 warp yarns per inch and 60 weft yarns per inch, the weight of weft yarns being abo~t half of the total weight of the fabric ~before any napping or im-pregnation~.
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Example 12 Example 9 is repeated except that the microporous layer is about o.6 mm thick and the fabric is a sateen fabric (having 60 warp yarns per inch and 60 weft yarns per inch, each of which is a 75/25 polyester/cotton staple fiber blend~ said ~abric weighing 8.5 oz./yd (200 glm ~ and having been napped so that its thickness in the final impregnated laminate is about 0.75 mm, of which about 0.25 mm is in the nap.
The resulting thicker composite, about 1.4 mm thick, is more suitable for making lasted menls shoes while the products of the other Examples are more suitable for lasted woments shoes.
Example 13 Example 9 is repeated except that in each case the fabric is a sateen fabric having 60 warp yarns per inch and 60 weft yarns per inch, each of the yarns being of a 75/25 blend of polyester/cotton staple fibers, said fabric weighing 7 ounces per square yard (240 g/m ), said fabric having been heat set - -at 240 C and napped to bring about 10% of its weight (about 20% of the weight of the weft yarns~ into the nap. -~
Example 14 Example 13 is repeated except that the yarns are of 100% polyester ~Q staple fiber.

Example 15 Example 13 is repeated except that the proportions of cotton and polyester fiber are 50/50 rather than 75/25 and the weight of the fabric is about 8 ounces per square yard (270/m ).
Example 16 This ~xample illustrates the effect of the napping on the fabric -~
structure and properties.i~i4/1 sateen weighing about 6.5 to 7 ounces per square ;~
yard and composed of yarns of a blend of 75% polyeth~lene terephthalate and 25% cotton, with 44 weft yarns per inch and 80 warp yarns per inch, the weft ' .:
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~l~36~5 having more fiber than the warp yarns, is napped on that face which has a pre-ponderance of weft yarns. As a result of the napping thewidth of the~
fabric, originally 62 inches, decreases to 57-l/2 inches, the weight per square yard rises to 7.66 ounces, the number of warp yarns per inch rises to 90 while the number of weft yarns per inch remains at 44. Thus the napping operation~ which pulls portions of the filling yarns from the main fabric structure to form the nap~ brings the warp yarns closer together and shrinks the fabric about 10%, increasing the crimp of the fil]ing yarns. The napped fabric has the following characteristics (for references~ see the Wellington Sears Handbook of Industrial Textiles by Ernest R. Kaswell, pub~ 1963 by We]lington Sears Company, Inc., N~Y., the appropriate pages of that book are given in parentheses below): gauge, thickness 0.026 inch (pages 571-2); con-traction, warp 3.88%~ weft 10.39% (page 454); crimp, warp 4.04%, weft 11.60%
(page 4543; yarn No.~ warp 19~03/l~ weft 7.86/1 ("indirect" pages 411-412, non-metric); grab strength, warp direction 244 pounds, weft direction 196 pounds (ASTM grab, Instron~ machine haYing jaws padded with rubberized duct, pages 470-471); elongation at break, warp direction 28.77%, weft direction 41.10% (pages 559-a61~; tongue tear strength, warp direction 31 pounds, weft direction 34 pounds (Scott~ J machine, pages 489-492); trapeæoia tear strength, warp direction 61 poundsg weft direction 47 pounds (Scott~ J machine, page 493); bursting strength 367 pounds per square inch (Muellen~ tester pages 474 477).
The fabric of Example 16 is somewhat unbalanced in construction and the unbalance is increased by the napping. It is often preferable to use a fabric having a more balanced construction~ one having about the same numbers of warp and weftl yarns per inch, e.g. 80 warp yarns per inch and 80 weft yarns per inch~
Where the fabric is to be exposed to elevated temperature during the process of manufacturing the product (e.g. in the processes of the foregoing ~ Trademark 39 : ~ : - .~ .. -~ ~6~3~

Examples 7-16) it is preferable in accordance with con~ention practice~ to have the fabri~ heat-set before using it in the laminating process so as to ayoid undesirable heat-shrinkage during the process. For instance the heat setting may be effected in well known manner to produce a fabric which has little shrinkage~ e.gO a shrinkage of less than 2% in the lengthwise ~machine) direction and less than 1% in the cross-wise direction ~hen subjected (forg say~ 3 minutes) to the highest temperature used in the process.
Example 17 This Example employs the napped unimpregnated fabric of Example 16.
The nap o~ the fabric is thPn impregnatedin two knife-coating passes as in Example 22 to deposit a total of about 1.5 to 2 oz./yd of elastomeric im-pregnant after which the unnapped *ace of the impregnated fabric is then ad-hered to the microporous sheet face of an assemblage of release paper~ poly-urethane layer and microporous polyurethane sheet as described in Example 2, using the adhesive described in Example 7.
Example 18 Example 17 is repeated except that the microporous sheet material has a thickness of about 0.030 inch (about o.76 mm).
Example 19 In this Example there is employed a 4/1 weft sateen weighing (after napping) 6.6 oz. per sq. yd. and composed of yarns of a blend of 75% poly-ethylene terephthalate and 2S% cotton, with about 60 warp yarns per inch and 60 weft yarns per inch, the fabric is heavily napped, the napping elements pulling out fibers primarily from the weft yarns and the extent of napping (as eyidenced by the thickness of the resulting nap~ being considerably greater ~;
than that shown in ~igures 12 to 17. The napped fabric is impregnated in~t~o passes by knife coating. Owing to the thicker nap~ having a greater amount of - ~-fiber therein~ the nap takes up a greater amount of impregnant~ the unimpreg-nated napped fabric has a weight o about 6.6 ounces per square yard, while~

- - - - - - : . : . -the nap-impregnated l`abric weighs about 9.9 ounces per square yard, so that the ~eight gain is some 50% of the original weight. This thickness of the napped fabric ~measured under compression as described above) is 0.026 inch (about o.65 mm) before impregnation and 0.045 inch (about 1.15 ~m) thereafter.
As in the previously described nap_impregnated fabrics there are thin webs of impregnant ~hich joint and bridge neighboring fibers~the outlines of the in-dividual nap fibers are still clearly evident the surface which still has the texture of those individual fibers, giving it to the feel of a fabric surface, and the nap has numerous open spaces and is thus still readily compressible~ ;
though much more resistant to compression than the unimpregnated nap. The opposite, unnapped~ face of the impregnated fabric is then adhered to the microporous sheet face of an assemblage of release paper, polyurethane layer and microporous polyurethane sheet as described in Example 2~ using the ad-hesive described in Example 7. The thickness of the resulting mens-weight shoe upper material is about 1.65 mm. (about o.o6s inch).
The impregnant used in this Example 19 is made by mixing 35.2 parts Impranil CHW~ 99.2 parts acetone and 24~8 parts methyl CeIlosolve~ acetate and then, jus-~ before use, adding 7.8 parts of a concentrated dispersion of carbon black (RBH #5485) and 3.85 parts of Imprafix TRL~ Impranil~ CHW is a hydroxyl-terminated polyester and Imprafix T~L is a polyfunctional isocyanate, these react in situ to form a high molecular weight elastomeric cross-l;nked polyurethane.
One~suitable carbon black dispersion contains 15% of the carbon black, 22/5% of vinyl resin (e~g. vinyl chloride-vinyl acetate copolymer VYHH) and the balance volatile solvents (such as methyl ethyl ketone)~ Other pigmen~s ~-may be used to impart a unifo~ coloration to the impregnated napped face~
In the ma~ufacture of shoes~ ce~tain portions of the upper material (such as the portions that are formed into the toe of the shoe) are subjected to severe bending with accompanying compression of the underside. The low ~ Trademark 3~ 4~

density impregnated nap is highly compressible. This may contribute to the excellent behavior of the laminate in shoe-making. In addition, in shoe mak-ing the stretching of woven fabric-backed leather substitute materials often causes stressing in a bias direction in which the tensile modulus of the material is relatively low; that is, the rectangular weave pattern of the fabric is easily distorted into a rhombic or diamond pattern by forces exerted in the bias direction. This can result in wrinkling of the skin layer. In the structures of this invention the bonding by nap-impregnation increases substantially the tensile modulus in the bias direction so tha-t the distortion of the weave pattern, and resulting wrinkling, is significantly reduced or eliminated. ;
The fibers of the nap are usually of a denier per fiber such as is conventionally employed in textile fabrics, e.g. in the range of about 1 to 10 denier, such as about 2 to 4 denier per fiber. The nap is preferably not a dense one and is preferably unsheared. Typically the number of nap fibers per square inch is below 5,000, usually less than 3~000, such as about 13000 or -2~000; this number may be measured from a photomicrograph (such as taken ~ith a scanning electron microscope) by drawing two one inch lines at right angles to each other on the photomicrograph, counting the number of nap fibers which cross each line~ and multiplying the sum of those two numbers by the magnifica-tion of the photomicrograph; thus, if on a photomicrograph taken at 60x, aone inch line drawn in the warp direction crosses 10 nap fibers while a one inch line drawn in the weft direction crosses a lesser number3 such as 6 nap fibers~
the total will be (10 + 6) x 60 = 960 nap fibers per square inch. It wiLl be noted that in the napped fabrics made by conventional napping techniques (with-out shearing the nap) the number of nap fibers seen to be crossing the line drawn in the warp will be less than those crossing the line at right angles thereto; also~ by unravelling such fabrics one can see that the nap fibeirs originate primarily from the wefting yarns.

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The rotating blades of skiving ~ni`~stypically are about 3 mm thick, the internal angle at the cutting edge of the blade being, say about 20 . They may be flat disks rotating about an axis normal to -the plane of the sheet material (as in the Amazeen Skiver) or rotating hollow cylinders rotating about an axis paraIlel to the p~ane of the sheet material (as in the Pluma* Skiver).
In the preerred forms of the invention, the bonding of the napped fibers has no substantial effect of the breathability o~ the product.
A ~icroporous polyurethane sheet material of the type employed in the fore~oing Examples was tested for its swelling characteristics in various solvents with the following results~

Solvent Initial Wt, after ~ wt. increase % solvent in ~W~ight swelling on original wet sample A. Acetone .4438 gm 1 9300 gm 335 77~0 B. Ethyl Cellosolve ~4350 gm 2~2200 gm 410 80.4 Acetate C. Mixture of 4 parts ~4760 gm 2~3750 gm 399 8006 A and 1 part B
D. Methylene Chloride .4381 gm 3~8500 gm 778 88~6 ~ -On a volume basis:

Solvent Initial Initial Dimensions% volume Dimensions Volume after swelling increase on cm cc cmcc original A. Acetone 7x4~5x~0440 1~39 8.5x5x.o523 2.2259~7 B. Eth~vl Cellosolve 7x4~5x~431 1~36 8~3x5X~o4g4 2~05 50~7 Acetate C. Mixtura of 4 parts 7x4~5x~0453 1~43 ~o7x4~9x~0541 2~31 61~5 A and 1 part B
D. Meth~lene Chloride 7x4~x~0426 1~34 995x5~5x~0517 2~70 101~5 In the tests~ samples of the microporous sheet material are immersed in the sol~ents for four~hours at room telsperature and both the weight and Trademark ~43~

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volume increases recorded. The samples are checked after a further two hours and show no further increase~ A~ter removal of the solven~s by drying the samples are all found to regain their original dimensions.

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Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for making an artificial leather sheet material which comprises providing a sheet of microporous preformed elastomeric polyurethane material having on one of its faces a second thermoplastic elastomeric poly-urethane of lower melting point than said first mentioned polyurethane, said second polyurethane having a hot tacky adhesive surface and pressing the hot tacky adhesive surface against the surface of a permeable fabric of inter-laced multi-fiber yarns.

2. A process as claimed in Claim 1 in which the preformed polymer layer is maintained in adherent, but strippable, relationship with a dimensionally stable support whilst the hot tacky adhesive surface is provided and whilst the tacky adhesive surface pressed against the surface of the permeable fabric of interlaced multi-fiber yarns.

3. A process as claimed in Claim 1 in which the tacky adhesive surface is provided by applying to a surface of the preformed sheet an adhesive com-prised of thermoplastic elastomeric polyurethane of lower melting point than the polyurethane of the microporous polyurethane, drying to remove any solvent present and then heating it to render it tacky.

4. A process as claimed in Claim 1, 2 or 3 in which the tacky adhesive surface is provided by a hot melt adhesive.

5. A process as claimed in Claim 1, 2 or 3 in which the density of the sheet of preformed polyurethane material is at least 0.3 g/cm3.

6. A process as claimed in Claim 1, 2 or 3 in which the density of the sheet of preformed polyurethane material is the range 0.3 to 0.4 g/cm3.

7. A process for making an artificial leather sheet material which comprises providing a fabric having an interlaced structure of multi-fiber twisted yarns, teasing from yarns of the said fabric a nap of fibers anchored within said twisted yarns, bonding together fibers of said nap, the bonding of the nap being such that the bonded nap has a void volume of above 50%, providing a sheet of microporous preformed elastomeric polyurethane material having on one of its faces a second thermoplastic elastomeric polyurethane of lower melting point than said first mentioned polyurethane, providing a hot tacky adhesive surface on said second polyurethane and pressing the hot tacky adhesive surface against the surface of the fabric remote from the bonding nap.