US3829351A

US3829351A - Stiffening material for shoe parts

Info

Publication number: US3829351A
Application number: US00293078A
Authority: US
Inventors: A Closson; H Beckwith
Original assignee: BECKWITH CORP
Current assignee: BECKWITH CORP; BECKWITH CORP US
Priority date: 1972-09-28
Filing date: 1972-09-28
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13
Also published as: DE2340222A1; FR2201617A5

Abstract

THIS INVENTION PROVIDES A STIFFENING MATERIAL FOR SHOE PARTS COMPRISING A NON-WOVEN FABRIC IMPREGNATED WITH A RESIN. THE FABRIC COMPRISING A SELF-SUSTAINING BATT OF MONWOVEN FIBERS EXTENDING GENERALLY IN THE WIDTHWISE DIRECTION OF THE FABRIC AND A PLURALITY OF ROWS OF YARN STITCHES EXTENDING GENERALLY IN THE LENGTHWISE DIRECTION OF THE FABRIC. THE ROWS ARE SPACED APART A DISTANCE LESS THAN THE AVERAGE LENGTH OF SAID FIBERS.

Description

Aug. 13, 1974 A. w. CLOSSON ETAL 3,829,351

STIFFENING MATERIAL FOR SHOE PARTS Filed Sept. 28, 1972 United States Patent Office Patented Aug. 13, 1974 3,829,351 STIFFENING MATERIAL FOR SHOE PARTS Addison W. Closson, Cambridge, and Harry L. Beckwith, Dedham, Mass., assignors to Beckwith Corporation, Wakefield, Mass.

Filed Sept. 28, 1972, Ser. No. 293,078 Int. Cl. A43c 13/14; D/04h 5/02 US. Cl. 16150 12 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a new stiffening material useful for forming shoe parts, particularly box toes and counters and to a method for making the same.

Prior to the present invention, box toe and counter stiffeners have been made by impregnating a woven or felted fabric or a needled fabric with a resin composition and thereafter fusing the resin. While these fabrics have been satisfactory for use in box toe and counters, their strength characteristics have not always been satisfactory, particularly along the bias, and their ability to distribute impact load is undesirably limited. In addition, these materials are relatively uncompressed and thick and they tend to show up when incorporated in the shoe because of their bulk. Relatively thick stiffening materials also are undesirable in the resin fusing step. The thermal conductivity of the material is reduced because of the increased thickness thereby requiring either higher curing temperatures or increased residence time during heating. When solvent fusion is employed, thicker materials absorb greater amounts of solvent which must be removed subsequently. Attempts to reduce the thickness of these materials have not been successful since the strength characteristics of the resultant material is undesirably reduced. In addition, the concentration of resin needed to form the final material is relatively high and therefore costly.

It has been common practice to impregnate a flannel fabric with a resin latex which is fused subsequently to form a stiffening material for shoe parts. While this material is satisfactory in some applications, very often it is undesirably brittle. The undesirable brittleness characteristics of this stiffening material arise since the fiber concentration at the surfaces of the stiffening material is too low to provide flexibility to the resin. In addition, in cotton flannel the fiber density within the interior of the flannel is too high to absorb sufficient resin to provide the desirable strength characteristics of the resultant stiffening material. The same brittleness problem arises from the use of fabric formed by needling rayon or nylon fibers into a scrim since these needled fabrics tend to pick up a high concentration of resin as high as 80% by weight of the final product. Attempts to increase the density of the fibers in the needled fabric to reduce the concentration of resin in the final product have not been completely successful and the resultant stiffening material is too thick and lofty for the most satisfactory use for shoe toes.

When employing resin-impregnated, double napped, cotton flannel sheets, counters must be cut across the sheet from selvage to selvage to obtain the stretch necessary to avoid counter wrinkling or breakage. This type of cut is used also to attain maximum hardness since the warp fibers extend vertically in the counter placed in the shoe and have no stretch thereby reinforcing it. This cutting requirement results in a relatively large portion of the sheet being wasted.

The stiffening material of this invention comprises a non-woven fabric impregnated with a resin which fabric comprises a self-sustaining batt of carded non-woven fibers such as rayon or nylon extending generally in the widthwise direction and a plurality of rows of yarn stitches extending generally in the lengthwise direction of the fabric. The non-woven fiber need not extend in a direction parallel to the widthwise direction but can be slightly angled from the width-wise direction up to about 45. The fibers employed have an average length generally between about /2 and 4 inches and the rows of yarn stitches are spaced apart a distance less than the average length of the fibers, generally between /a and of an inch.

The stiffening material of this invention provides substantial advantages over those of the prior art. The outstanding and surprising advantage of the material in this invention is that it exhibits greater tensile strength along the bias as compared to the warp or fill tensile strength. Since impact for a box toe is regulated primarily by the distribution of the impact force throughout the area surrounding the point of impact, the higher strength against rupture on the bias is exceedingly important. This observation is in direct contrast with the stiffening materials of the prior art wherein the maximum tensile strength is in the warp and fill direction and the tensile strength along the bias is some intermediate value, usually the average of the warp and fill tensile strength.

The stiffening material of this invention also is far less brittle than those of the prior art thereby permitting the use of more severe conditions during a molding step during which the material is incorporated in a shoe construction. The stiffening materials of this invention also has a thinner gauge than those of the prior art and therefore will show through a leather upper to a lesser degree, which in some cases eliminates the need for skiving. The reduced thickness also permits the use of less severe conditions during heat curing and reduces solvent pick-up during solvent fusion. 1

Furthermore, the resin-impregnated sheet material of this invention can be cut in any direction to form shoe parts having satisfactory stretch and strength characteristics. Thus counters and liners cut from this sheet material, regardless of the orientation of the cut, have sufficient stretch to avoid wrinkling or breakage under normal impact forces and have excellent hardness characteristics even when cut on the bias. These characteristics permit cutting the sheet material while minimizing waste material.

The fabric of this invention can be formed from a wide variety of fibers including rayon, polyamides (nylon), polyester, cellulose, wool, blends thereof or the like. When it is desired to increase the flexibility and resilience of the stiffening material, it is preferred to employ a fabric formed from a polyamide. When it is desired to improve the stiffness and strength characteristics of the stiffening material, it is preferred to employ a fabric formed from rayon fibers.

Suitable resin latexes include styrene, styrene copolymers, such as styrene-acrylates, styrene-butadiene, and styrene-acrylonitrile or polyvinylchloride or polyvinyl acetate, natural rubber and low molecular weight styrene impregnated as a hot melt or the like. In the final stiffening material, the resin comprises between about 50 and weight percent based upon the weight of impregnated fabric. The final stiffening material generally has a thickness between about .030 and .090 inch, and can be controlled by varying the density of the fibers in the base fabric.

The strength characteristics of the stiffening material also can be varied by varying the distance between the rows of stitched thread, the strength of the yarn employed in the stitching and the density of the stitch. Higher' strength characteristics are obtained by reducing the distance between the stitch rows, increasing stitch density or employing stronger yarns. There is no limit as regard to the type of stitch with zig zag, chain stitching, or lock stitching being satisfactory. In addition, stitching beween the rows can be provided such as example shown in U.S. Pat. 3,329,552 issued July 4, 1967. This patent also discloses one method for laying the fibers in a widthwise direction.

The method for forming the stiffening material of this invention comprises impregnating the fabric with a resin latex, drying the impregnated fabric and curing or fusing the resin therein by heating or solvent fusion. The method of this invention will be more fully described with reference to the accompanying drawings.

FIG. 1 is a schematic view of the process steps of this invention.

FIG. 2 is a plan view of a box toe of this invention.

FIG. 3 is a cross sectional view of the box toe taken along lines 33 of FIG. 2.

Referring to FIG. 1, the fabric 1 is advanced into a bath of resin latex 2, over guide roller 3 and beneath the surface of the bath 2 under guide roller 4 so that the base fabric 1 is saturated with the resin latex. After leaving bath 2, the impregnated fabric 5 is passed between squeeze rollers 6 and 7 to remove excess latex on resin therein. The saturated fabric 5 then is passed over heated or cooled drums 8 and 9 and through squeeze rollers 10 and 11 to obtain an impregnated fabric 12 having the desired thickness. Thereafter, the resin can be fused or cured conventionally such as by heating or by being contacted with a solvent which fuses the resin.

Referring to FIGS. 2 and 3, the stiffening material comprises a base fabric formed from a batt of non-woven fibers 15 which extends generally in the widthwise direction of the fabric and a plurality of rows of yarn stitches 16 which extend generally in the lengthwise direction of the fabric and, as shown in FIG. 3, can comprise a stitch-loop configuration. As shown, the box toe 17 is cut at an angle to its thickness along the base 18 thereof to promote fitting of the box toe in a shoe.

The following examples illustrate the present invention and are not intended to limit the same.

EXAMPLE I This example illustrates a method for forming the stiffening material of the invention and the superior strength characteristics of this material as compared with stiffening material made with a needled base fabric or a cotton flannel fabric. A stitch-bonded base fabric comprising rayon fibers extending generally in the widthwise direction and stitched rows of a polyester yarn extending in the lengthwise direction of the fabric was impregnated with a styrene acrylate latex, dried at 120 C. for about 8 minutes and fused by toluene immersion. The base fabric, prior to resin impregnation weighed 7.8 oz. per square yard, the yarn was loop-stitched with twelve stitches per inch and the rows were inches apart. The cured stif fening material contained about 70 wt. percent resin and was .043 inches thick.

The same resin impregnation and curing steps were repeated with a needled fabric comprising rayon fibers needled into a cotton scrim and with a cotton flannel fabric. The needle fabric prior to impregnation weighed 8 oz. per square yard and the final cured stiffening material formed therefrom was .073 to .083 inches thick. The cotton flannel weighed 8.4 oz. per square yard and the final cured stiffening material formed therefrom was .058 to .065 inches thick. Theneedled stiffening material contained 77 weight percent resin based upon the final stiffening material. The cotton flannel stiffening material contained 73 weight percent resin based upon the final stiffening material.

Each stiffening material was tested for tensile strength and stretch at rupture on a Scott apparatus with the following results:

TABLE I Stitch bonded abric Needled fabric Flannel Tensile Stretch Tensile Stretch Tensile Stretch (lbs.) (in.) (lbs.) (in.) (lbs.) (in.)

The procedure of Example I for forming stiffening materials from a base fabric and a resin composition was repeated With a double nap cotton flannel fabric weighing 6 /2 oz. per square yard, a wide stitch bonded fabric formed from rayon fibers with stitch rows spaced /8" apart and weighing 7 /2 oz. per square yard, and a narrow stitch-bonded fabric formed from rayon fibers with stitch rows spaced apart A" and weighing 5 /2 oz. per square yard. The cured resin-wide stitch bonded material contained 77 weight percent resin. The cured resin-flannel material was .036 inches thick and contained 73 Wt. percent resin. The cured resin-narrow stitch-bonded material was .038 inches thick and contained 70 weight percent resin. Each material was tested as described in Example I with the following results:

TABLE II Wide stitch- Narrow stitch- Napped flannel bonded bonded Tensile Stretch Tensile Stretch Tensile Stretch (lbs.) (in.) (lbs.) (in.) (lbs.) (in.)

28 16 1 ,18 28 48 2% a l 2% 17 2% a 34 17 20 2% 53 2% As shown in the above table, only the stitch bonded material of this invention had a higher tensile strength on the bias as compared to the warp or fill tensile strength.

We claim:

1. A stiffening material for shoe parts comprising a non-woven fabric impregnated with a resin, said fabric comprising a self-sustaining batt of non-Woven fibers extending generally in the widthwise direction of said fabric and a plurality of rows of yarn stitches extending generally in the lengthwise direction of said fabric, said rows being spaced apart a distance less than the average length of said fibers.

2. A stiffening material for shoe parts comprising a non-woven fabric impregnated with a resin latex, said fabric comprising a self-sustaining batt of non-woven fibers extending generally in the widthwise direction of said fabric and a plurality of rows of yarn stitches extending generally in the lengthwise direction of said fabric, said rows being spaced apart a distance less than the average length of said fibers. fib3. The material of claim I wherein the fibers are rayon ers.

4. The material of claim 2 wherein the fibers are rayon fibers.

5. The material of claim 1 wherein the fibers are polyamide fibers.

6. The material of claim 2 wherein the fibers are polyamide fibers.

7. The material of claim 1 wherein the fibers are polyester fibers.

8. The material of claim 2 wherein the fibers are polyester fibers.

9. The material of claim 1 wherein the fibers are cellulose fibers.

10. The material of claim 2 wherein the fibers are cellulose fibers.

11. The material of claim 1 wherein the fibers are wool fibers.

12. The material of claim 2 wherein the fibers are wool fibers.

6 References Cited UNITED STATES PATENTS 3,336,183 8/1967 Larner, 11., et a1. 161-Di' g. 2 3,329,552 7/1967 Hughes 161-52 2,676,128 4/1954 Piccard 161--Dig. 2 2,723,935 11/1955 Rodman 16l-Dig. 2 2,498,077 2/1950 Goldberg 28-77 X 3,329,116 7/1967 Attwood et a] 28-77 UX 2,125,798 8/1938 McMurray 3677R FOREIGN PATENTS 1,147,657 4/1969 Great Britain 16150 PHILIP DIER, Primary Examiner U.S. c1. X.R.

2877; 36-77; 161--Dig. 2