US1552037A - Shoe stiffener - Google Patents

Description

Patented Sept. 1, 1925.

UNITED STATES PATENT OFFICE.

ALBERT L. CLAPP, OF DANVERS, MASSACHUSETTS, ASSIGNOR TO BECKWITH ZlYIANU-- FACTURING COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

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To all whom it may concern:

Be it known that I ALBERT L. CLAPP, a citizen of the United States, residing at Danvers, in the county of Essex and State of Massachusetts, have invented new and useful Improvements in Shoe Stiflt'eners, of which the following is a specification.

This invention has for its object to produce a fibrous material containing a thermo. plastic compound, for use as a shoe stifl'ener, such as a. box toe or box-toe blank,the more especial object being to provide a material of the class referred to which may be manufactured by the aid of the machinery common to the manufacture of paper.-

It has been almost the universal practice in the manufacture of such thermo-plastic or moldable box toes, first to form a fibrous sheet usually of wool or cotton and Wool felt, then to saturate or impregnate the sheet with a molten th enno-plastic compound or mixture, and, after the latter has cooled and set, to cut box-toe blanks of appropriate size and Shape therefrom. A box-toe blank thus formed has certain highly desirable characteristics flowing from the nature of the fibrous sheet. Since the sheet is a true felt, with numerous pores and interstices, it has the capacity for absorbing and carrying a large amount, proportionate to its weight, of the thermo-plastic compound; and, because, of the long fibers of which it is composed, it may (when its contained thermo-plastic compound is fluxed or plastic) be stretched about the toe end of the last Without dan er of tearing But the process of producing felt by the usual or common felting machine is a long and expensive operation and the output. is limited.

Any stiffened, or moldable box toe mate-' rial must be capable of being stretched without tearing sufliciently to permit its being drawn about the last in the pulling-over and end-lasting operations; that is, it must be possessed of a certain degree of tensile strength and et must be capable of being stretched, and toughness and durability. A,

After many experiments, I have succeeded in producing from an aqueous pulp a box toe material having the thermo-plastic com- 1 pound incorporated therein and possessing the necessary qualities' and characteristics hereinbefore referred to. This material,

at the same time Application filed December 21, 1922. Serial' No. 608,358.

which is sheeted on a common paper-making machine of the cylinder type (i. e. awet machine), contains a very large-percentage of the thermo-plastic stiffening compound, may be stretched and molded about the end of the last without danger of being torn in the stretching operation, and possesses that stiffness and resiliency which is necessary to produce a successful box toe.

The t-hermo-plastic compound is incorporated in the pulp prior to the formation of the sheet,

and one of the problems to be solved in accomplishing this result is to efl'ect the retention of the thermo-plas'tic compound in the pulp. l v v The pulp must be made of those'materials which-will impart to the finished sheet the optimum characteristics hereinbefore referred to. to use ce'llulosic material or wood pul together with long hairs such as cattle ha1r or wool. It is recognized by paper manu- I have found that it is possible facturers that the stock must be capable of being formed on the cylinder mold and built up on the make-up roll, and that it must be of such character as will permit the incorporation of several times its weight of the thermo-plastic compound. The

thermo-plastic compound must be of such character that it may be powdered or finely reduced, that it should possess a relatively short melting-point-lag so that it will set rapidly, when cooled after once bein in molten condition, and, that it shoul be capable of being softened upon the application of moderate heat. As the thermoplastic compound, I may use various bitumens, resins, gums and waxes in varyinghaving the characteristics last referred to, are comprehended within the phrase.

thermo-plasticcompound.

from those hereinbefore' The following example will serve to illustrate a box-toe material embodying the invention and the process of producing it.

5 parts of cellulosic material, such as sul- I phate or sulphite pulp or waste kraft or sulengine together with sufficient water to ensure the circulation of the stock, and are beaten until the leather has partially dissolved and the cellulose fibershave been more or less hydrated. While the leather is artly dissolved, a small uantity of gelatmous fibrous leather resi uum remains. now add to the -beater about 5 parts of cattle hair (or wool), and, lifting the beater roll from the bed plate, I operatethe beating engine until the hair is thoroughly mixed into the stock. It is desirable. not to cut the hair into short pieces but to leave it in relatively long condition, preferably so that it retains its original length. I now add to the stock a large amount of the finely- .divided thermo-plastic compound, say from 90 to 120 parts thereof, and the operation of the beater is continued until the thermoplastic compound has been thoroughly distributed throughout the stock. In\ the particular example given, I ordinarily employ about 90 parts of a blend or mixture consisting of certain ingredients in the following proportions; namely, about 80% of acid resins of which about one-sixth'is copal and the remainder rosin, about 15% montan wax, about 3% china wood oil, and about 2% of lime. These ingredients are thoroughly mixed together when molten and the lime reacts with certain acids of the resins to form a calcium resinate or soap.

After the thermo-plastic compound is thoroughly incorporated in and distributed throughout the pulp, I add about 20' parts of aluminum sul hate and the stock is further beaten unt1l the alum is distributed throughout the pulp and has precipitated the 'dissolved leather in the form of a gelatinous hydrate which coagulates or precipitates and fixes upon the fibers the particles of thermo-plastic compound which are in the stock. Thev aqueous pulp is now transferred to a paper-making machine and formed into sheets of the desired caliper. Each sheet as stripped from the make-up roll is dried flat and then subjected to sufficient heat and pressure to melt the contained thermo-plastic compound and cause it to penetrate throughout and coalesce within the sheet. To accomplish this result, the sheet niay be passed through calender rolls heated to the necessary temperature. The sheet is now cut into blanks of appropriate size and shape to serve as shoe stifl'eners, such, for example, as box toes or counter stiifeners. v

I may incorporate .in the aqueous pulp.

terial an /or to act as a filler.

I the fibers so that only a relatively small proportion of the disintegrated thermo-plastic compound escapes with the white water. The fibrous leather residium aids in forming the sheet on the wet machine and increases the strength of the resulting sheet. The presence of the long hairs in the stock permits the stock to be stretched and molded without being sheared or torn in the molding operation, whereas the cellulose fibers are necessary to give suflicient strength and formation to the sheet.

A box-toe blank, formed as herein de scribed, possesses those characteristics "and qualities which enable it to be successfully used in lieu of those heretofore produced, in which the felt is saturated With molten thermo-plastic compound, but may be pro.- duced in very large quantities and at relatively low, expense. The fibrous materials whichv are utilized are of themselves inexpensive; namely, chemical .wood pulp, cattle hair and other scrap. If sulphite or sulphate screenings be used, substantially all of the fibrous materials are of the nature of waste materials or by-products.

In the foregoing description it will be observed that the proportion of thermoplastic compound "to the cellulosic material and the hair is about 9 to 1 by weight, and, in fact, it may be even greater. finished product, the ratio of thermo-plastic compound to fibers is as 7.5 to-1,-a result which, so far as I know, has never before been achieved. Consequently the box toe when molded possesses, to a maximum degree, stiffness, toughness and resiliency, so

that its shape isnot easily distorted when.

incorporated in a shoe. The box-toe blank may be skived to present a sharp edge,

-which of itself is highly desirable in. the

In the .i

a precipitate flexible upon the application of heat-and 3. A shoe stiffener adapted to be made limp and flexible upon the application of the fibers being in heat and comprising cellulose fibers, cattle hair, leather fibers, and thermo-plastic compound, and a precipitate formed by the reaction of a precipitant with dissolved leather, felted relation and the thermo-plastic compound being distributed throu hout the fibers.

'4. g process of making shoe stifl'eners, which comprises pulping cellulose fibers, leather in the presence of caustic soda, long fibers such as" cattle hair, divided thermo-plastic compound, then adding a precipitating agent for the dissolved leather, and sheetmg the resultant pulp on a 'paper machine.

water,

and a finely- 5. A process of making a shoe stiffener, which comprises beating together. cellulose fiber, tanned leather and caustic soda in until the leather is more or less dissolved, incorporating'long fibers and finelydivided or crushed thermo-pla'stic compound in the resulting pulp, addin a precipitating agent for reaction with the issolved leather,

and sheeting the pulpy mass on .a paper machine.

6..A process of making a fibrous 'inaterial suitable for shoe stifieners, which comprises forming an aqueous fibrous pulp, mcorporating a crushed thermo-plastic compound in the pulp, in the proportion of not less than six parts by weight of said compound to one part by weight of fibers, coagu ating and fixing the thermo-plastic compound on the fibers, and sheeting the resulting pulp in a paper machine.

In testimony whereof I have aflixed my signature.

- .ALBERT L. CLAPP.