US2541761A - Process of making shoe stiffeners - Google Patents

Description

Feb. 13, 1951 R. B. HARRISON 2,541,761

PROCESS OF MAKING SHOE STIFFENERS Filed Feb. 9, 1946 $1 w at (9630 2294/ Patented Feb. 13, 1951 PROCESS OF SHOE STIFFENERS Raymond B. Harrison, Braintree, Masa, assignor to Beckwith Manufacturing Company, Dover, N. 11., a corporation of New Hampshire pplication February 9, 1946, Serial No. 646,604

3 Claims.

My invention relates to shoemaking comprising, in one aspect, a novel process for maki shoe stiileners and, in another aspect, the shoe stiflener resulting from the practice of the process.

The shoe stiffener of my invention is particularly adapted for use in conjunction with the general process of shoemaking which has come to be known in the trade as the California process. The salient features of the California process consists in uniting off the last an upper and an insole, these elements being first carefully out and marked prior to assembly so that in the process of stitching them together draft and fullness are imparted to obtain a properly shaped shoe. This is a departure from most prior shoemaking methods in which the shape of the shoe is obtained by stretching an upper over a last, trimming off surplus portions of the overlasted margin, and securing the upper to the insole while .both members are in position on the last. In

accordance with the California process the last is inserted after the upper and insole have been united, not so much for the purpose of shaping the shoe as to render it still during the operation of attaching an outsole.

It has long been thought that it was impossible to incorporate into a California process shoe a toe stiffener or box toe of the conventional sort. In ordinary shoemaking a box toe is inserted between the lining and the upper before the shoe is lasted, and the stiffening and adhesive compound in the box toe is activated when it. is inserted. The subsequent lasting operations are carried out before the box toe becomes stiff, with the result that the stiffening of the box toe takes place while the shoe is on the last. During the stiffening process the box toe becomes adhesively united to the lining and the inner surface of the upper. In the California process the lining does not usually extend forwardly of the throat. Consequently if a conventional box toe impregnated throughout with a stiffening and adhesive compound were incorporated into the structure of the shoe and activated prior to the insertion of the last, the box toe would adhere not only to the upper but also to the surface of the last, and the subsequent withdrawal of the last would be impossible.

In the pending application for Letters Patent of the United States Ser. No. 640,244, filed January- 10, 1946, by Walter H. Heaton and Harry H. Straw, now Patent No. 2,480,078, there is disclosed an improved shoe stiffener capable of use in California process shoes and a process of shoemaking involving the use of their improved stillener. The present invention comprises an improvement on the stiffener disclosed in said 00- pending application. Accordingly, the primary object of my invention is to produce an improved shoe stiffener capable of being incorporated in the structure of the California type shoe.

Another object of my invention is to provide a desirable .process of makingimproved stiffeners capable of use in California type shoes, the stiffeners being characterized by a distinct film or ply of stiffening material and an independent film supplying the requisite adhesive qualities to the box.

The process of my invention includes the steps of bonding two thin'sheets of fibrous material together with an intermediate layer of thermoplastic material and thereafter loading into one only of the sheets a thermoplastic stifiening and adhesive compound. The result is a three-ply sheet from which stifleners can be cut.- In the shoe the inner fabric ply is a non-adhesive reinforcement forming a part of the stiff box toe structure; the intermediate ply of thermoplastic material is relatively stiff; and the fabric ply next the upper is not only relatively stiff but capable of being subjected to the action of an activating agent which renders the outermost surface of the plyadhesive and capable of being cemented by pressure to the inner surface of a shoe upper.

These and other objects and features of my invention will be more readily understood and appreciated from the following detailed description of a preferred method for producing my improved shoe stiffener, together with a description of a preferred manner of incorporating the improved stiffener in the structure of a shoe, the same being illustrated in the accompanying drawing, in which:

Fig. 1 is a diagrammatic view in cross-section showing the steps of forming the sheet from which the improved shoe stifieners may be cut,

Fig. 2 is a view in cross-section, on an enlarged scale, showing the three-ply sheet from which the stiifeners are cut,

Fig. 3 is a view in perspective of the improved shoe stiffener, and

Fig. 4 is a view'in cross-section through the h toe end of the shoe illustrating the manner in which the improved shoe stiffener is incorporated into the structure of the shoe.

As shown in'Flg. 'l, I provide two sheets of napped flannel or other suitable textile or fibrous material of the character commonly used in making shoe stiffeners. The sheets l0 and 12" are arranged to be fed continuously over a pair'of tensioning rolls l3 and then between a pair of pressure rolls H. A thin continuous sheet ll of thermoplastic material is directed between the sheets I and I2 and into the bite of the rolls H. The composition of the sheet II is not critical. There are many thermoplastic stiffening compounds which have been developed for use in the manufacture of shoe stiffeners and I contemplate that any one of a large number of such compounds, in unitary sheet form, may successfully be used in the process of my invention. For example I may utilize one of the vinyl ester resins, e. g. polyvinyl acetate, polyvinyl chloride, or a polyvinyl emulsion, polyvinyl acetate solutions made with any solvent such as acetone, benzene, toluene, methyl alcohol, etc.

As a specific example of one compound capable of use as material for the intermediate sheet II, and the best now known to me, there may be compounded with alcohol the following ingredients:

Percent Alvar (polyvinyl acetate) 28.2 Gelva (polyvinyl acetate) 33.3 Calcilm stearate 1.6 Phenol indene cumarone resin 12 Paracumarone resin 4 Lithopone 4.9 Wood flour 16 The unitary sheet H is introduced between the textile sheets Ill and I2, being heated suinciently to render it soft but not so much that it becomes molten. The pressure of the rolls l4 bonds the sheets l0 and I2 to the opposite surfaces of the sheet ll forming a unitary threeply sheet. Shortly after the composite sheet leaves the rolls 14 it encounters a stripper knife or doctor l5 which bears on the surface of the uppermost sheet l0. Behind the stripper knife I5 is disposed a mass ii of a thermoplastic and adhesive compound. The action of the knife I5 and the movement of the sheet It) causes the mass IE to load into and saturate the greater portion of the uppermost sheet Hi. It will be apparent that the continuous inner ply H of preformed thermoplastic material acts as a dam or barrier to the passage of the adhesive compound IG beyond or below the uppermost ply ID. The composition of the mass 16, that is, the thermoplastic adhesive impregnant, may also be selected from a number of compounds used to load fibrous material with a thermoplastic adhesive. I have found that in practice the following compound may successfully be employed:

Parts Stearic acid 668 Ethyl cellulose (N. 22) 300 Vistanex (polyisobutylene) 40 A cross section on an enlarged scale through the sheet thus produced is shown in Fig. 2. From this three-ply sheet I cut out shoe stiffeners of conventional shape and skive them from the untreated side as shown in Fig. 3 where the shoe stiffener is shown as made up of the untreated soft and flexible ply l2, the intermediate stiffening ply of thermoplastic material II and an outer full-sized ply ill of flannel impregnated with the thermoplastic adhesive compound.

In the manufacture of California type shoes incorporating in their structure the improved stiffener of my invention the stiffener 30 is placed on the inner surface of the upper at the toe portion thereof and caught into the seams which unite the upper 28 to an insole 28. As shown in Fig. 4, a seam 32 passes through the insole, the stiffener, and the upper 28: and a seam 36 passes through these elements and also through a cover strip 34 destined to be wrapped around the edges of the upper, the stiffener and the sole 26. Just before the last is inserted in the shoe the thermoplastic compounds in the stiffener 30 are activated by heat to render them soft and capable of being molded. One convenient method of introducing heat to the stiffener is shown in Fig. 4 wherein a goose-necked nozzle 38 is inserted into the shoe and steam admitted through the nozzle 38 which directs it against the stiffener 30. Thus the heat strikes through the untreated ply l2 and into the layers It) and II. When the layers l0 and II have become sufficiently soft and pliable, a last is inserted in the shoe and the usual sole-attaching operations carried out. The last forces the stiffener to conform to the contour of the toe portion of the last. After the sole-attaching operation has been completed, the last is removed. Inasmuch as the layer I2 is non-adhesive, there is no obstacle to the removal of the last. Furthermore, the layer i2 forms a suitable surface for the interior of a shoe and, in effect serves as a lining for the toe end.

The shoe stiffener herein described is more satisfactory than one obtained by merely loading a thermoplastic adhesive compound into one surface of sheet material for the reason that the finished shoe stiffener made according to my invention contains a greater amount of stiffening compound. Consequently the stiffener not only more faithfully conforms to the lines of the last, but will hold its shape over longer periods.

Having thus disclosed my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. The process of making a shoe stiffener which comprises feeding a sheet of softened thermoplastic composition progressively between two sheets of fibrous material and uniting the same to form a three-ply sheet, and thereafter progressively loading into one only of the outer plies of said three-ply sheet a thermoplastic stiffening and adhesive compound while the sheet of thermoplastic composition acts as a barrier to the passage of the latter compound beyond the ply which is being loaded.

2. The process of making a shoe stifiener which comprises interposing a sheet of softened thermoplastic material between two sheets of fibrous material, pressing the three sheets together to form a bonded three-ply sheet, loading one only of the outer plies with a stiffening and adhesive compound after the three sheets have been united and while the sheet of thermoplastic composition acts as a barrier to the passage of the latter compound beyond the ply which is being loaded.

3. The process of making shoe stiffeners which includes the steps of feeding a thin continuous sheet of thermoplastic material between two sheets of textile fabric and simultaneously softening the thermoplastic material and pressing the sheets into bonded condition, and thereafter progressively loading into the uppermost sheet only a thermoplastic stiffening and adhesive compound while the interposed sheet of thermoplastic composition prevents the latter compound from reaching the lowermost sheet, thus maintaining the lowermost sheet with its original texture.

RAYMOND B. HARRISON.

REFERENCES CITED The following references are of record in the file of this patent:

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