US1833151A - Resilient flexible sheet and method of making the same - Google Patents

Description

Patented Nov. 24, 1931 I UNITED stares WILLIS A. IBOUGHTON, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO BECKWITH MANUFACTURING COMPANY;

OF BOSTON, CHU- SETTS, A CORPORATION OF MASSACHUSETTS RESILIENT FLEXIBLESHEET AND METHOD OF MAKING THE SAME No Drawing. Application filed June 1,

' lates to material suitable for toe boxes in shoes, and for similar uses, such as for counters of shoes, or for other purposes to which the described material shall be found applicable. In the case of toe boxes this signifies a measure of stifiness coupled with resilience and the .ability to be softened by commercially suitable means so as to undergo the lasting operation whilesoft and then to become stiff in the lasted condition.

It is an object of the invention to provide a toe box material and a process of manufacture which shall embody all of the various qualities which are good or desirable in material for toe boxes or the like and shall in addition be easily controllable as to flexibility and resilience to suit the needs of different types of shoes; and it is especially a characteristic that the process, by a mass treatment. makes a softly resilient sheet which is an admirable material for a soft toe box without the sheet having to be worked'or treated in detail to produce a non-cracking flexibility.

Among the desirable properties to be embod ed in a toe box material are. that it should be low in cost: made of materials which are easily and always available; and capable of being wi ed into the shoe. so as to give a toe that is free from wrinkle, by an operation which is neither difficult, dirty nor expensive. TheLfinished box must lie smooth under the leather; be hard enough at its edges to hold the shape of the last and be flexible and resi ient at the middle of the arch: except as these requirements mav be modified in the case of soft-toe shoes. -The box must become aunit with the adiacent felt and lining of the shoe it must be adaptable to the vseveral principal processes of m nu cture of shoes. known. for example. as the McKay process, the turn shoe process. the welt process. etc.; must be reasonably waterproof; and must not weaken materially during wear. In addition it must be obtainable in various degrees of thickness, stiffness and resilient power, according to the desire of 1925. Serial No. 34,187.

the shoe manufacturer. The invention provldes a composite sheet material satisfying all of these requirements and allows of control of thickness and resilience of the product by changing factors in the process.

Brlefly stated the process in its best form comprises the dipping of a carrier sheet, preferably of cloth, such as a heavy cotton twill, into rubber latex of suitable stren h; drying the cloth, preferably under tension; and then treating the cloth with a liquid rosin mixture. Before the treatment with rosin the dried cloth may be passed between hot rollers thus cooking the solidified rubber material, which produces a result definitely better than when heat is omitted preceding the applica-- t on of rosm. When the hot rosin is applied some sort of reaction occurs. Whether this is a result of the heat in the hot rosin, comparable to the heat from the rollers, or is a physical or a chemical reaction between the rosin and the latex, I do not at present know; but it is certain that the resultant product is a sheet with greater resilience, that is, greater degree of flexibility coupled with the power of returning to original form.

I'he sheet is complete and ready for use after the rosin layer has solidified. It has the novel characteristic, as compared with other sheets to which rosin has been applied, that when thus made it does not tend to crack in lines, as does a sheet in which the rosin is applied directly to the cloth.

The flexibility of the product is controllahle by using latex of greater or less strength. \Vhere the product is used for toe boxes, and

when thehigher strengths of latex are used,

the sheet can he lasted without further sof-' tening; but for most purposes the stiffness, which results (after application of rosin) when latex of a lower degree of strength has been used, is requisite; and in this case the sheetmay be softened temporarily for lasting either by heat or by a solvent, or by other method, as for example, by applying a combination of liquids which will soften the rosin without taking it into solution.

In a modified form of the process the sheet of cloth may be treated with China wood oil or linseed oil in place of rubber latex. These ATENT orrrcafi drying oils, as well as caoutchouc, make gums, all being derivatives of or related to hydrocarbons of the terpene series. But when the dried sheets which have been treated with the drying oil are dipped into hot rosin nothing in the nature of a reaction occurs,v comparable to the reaction which .occurs when the hot rosin and the latex are put together, althougha minor reaction is observed. The result in this case is a sheet which can be used for a toe-box, but is not equal in quality to the\ sheet which results when the rubber latex is similarly used.

An illustrative example follows :any suitable cloth, such as heavy cotton twill, is dipped in rubber latex of strength, which is about one half the strength of ordinary commercial latex, or into latex of some other degree of strength which has been prepared or chosen according to the desired flexibility of the finished sheet. The greater the strength of the latex used theless will be the immediate stiffness of the finished sheet, other things beingequal. After the latex bath the sheet isdried, preferably in air slowly and under tension, whereby uniformity is produced as well as other qualities. It will then be found that the addition of the rubber has not changed the sheet much in aspect, in flexibility or in surface texture. It has given it somewhat of a waxy feel; and the rubber is deposited in and on the threads but does not fill the spaces between threads with any degree of completeness nor render the sheet impervious. .The sheet is then to be treated with 'a hot rosin composition. I use this general term ros n composition to describe a substance which may consist wholly of rosin or which may have'in it various gums, in

chosen proportions, for it is already known that gums may be used with rosin 'to obtain special desired qualities of cheapness or of physical characteristics. This step ma be carried out by passing the sheet into a ath of the molten rosin composition, under a roller in the bath, and then, after its emergence, between a pair of rollers, whose setting with reference to each other limits the thickness of composition that shall remain in and on the. sheet. Preferably these rollersare maintained heated, as by gas, but preferably not much above the temperature for producing desired fluidity of the rosin. If the lat ter has cooled upon emergence from the bath, the'heat from these rollers willsoftenit; and it will become evenly distributed; but preferably the rolls are set so that the sheet mov- .ing away from them, which as-it cools is found imperviously'coated with rosin, nevertheless does not have a smooth surface, but the rosin layer is so thin. that its exterior surface to an extent follows the-contour of the surface spaces between threads. The rubber :does not. prevent the rosin when heated by ,sure rollers.

' the hot rosin bath.

,known to me, having threads for if applied to the sheet on one side only it can be seen to strike immediately through the cloth upon reaching the hot pres- The. sheet coming from these rollers, after being allowed to cool, is ready to be cut into small pieces for use. Analysis will show that one of these pieces consists of the carrier sheet. impregnated with rubber "surmounted with two coatings, the first of which is the reaction product of the rubber and the hot rosin andthe second, outside of it, isthe rosin which did not get'close enough to the rubber to .get into the reaction, these all adhering together as an integral sheet.

An intermediate step which may be intro duced intothis process is to pass the sheet between hot rollers, or otherwise press it gently in the presence of heat, after the cloth has been saturated with latex and dried, thus cooking or curing the solidified rubber material, and this may be done without the presence of any vulc anizing reagent. In my experiments in this res ect rolls heated by gas flame were used, an the degree of heat applied was such that the rolls would sizzle when moistened.

latex, natural or synthetic, may be used, em-

bodying the colloidal aqueous suspension of rubber particles resembling rubber latex in its properties and actions; and it also appears that other gums, such as the drying oils, have some merit as substances with which to satuate cloth before passing it into In this description the rosin composition is-ty-pical of a substance which softens with heat or other treatment, and becomes stiff andof vitreous brittleness under ordinary atmos heric conditions. Rosin is the most avai able' substance of that sort at ties of cheapness an abundance, as well as the physical and chemical ualities that charv resent the commercla quallacterize it; but it will" be 0 vious that the invention 1s not limited in its scope to this particular substance.

The cloth andjru'bber make a thickish, mo-

bile, irregular bed under this thin layer of rosin or other stiff substance. If the rosin be applied too thickly, or be applied without rubber intervening, the sheet, after cooling and upon being bent will tend to crack in lines which is an'eflect to beavoided. But

assuming that the applied layer is moderthe pores of the fabric throughout withastiif 1 ately thin the finished sheet can be bent very considerably without the occurrence of noticeable fracture, and when released will spring back with a marked degree of elasticity. The resistance to bending increases with the use of thicker cloth. I do not ascribe this to any greater stifiness in the thicker cloth, but rather to the greater quantity of the rosin which becomes embodied in the structure while still the sheet as a whole has a. surface broken by the irregularities of contour of the threads. The intimacy of connection between the rubber and rosin, dueto chem:

ical reaction or strong physico-chemical adsorption of rosin on the rubber, gives to the product sheet a measure of stiffness uniform in all directions, with less brittleness and more permanent resilience than where theruhber is omitted. For the sheet to carry the rubber and rosin. cloth is preferable because of its strength; but in the cases where this strength is not needed a cheaper sheet may be substituted.

I do not herein claim as mv invention the impregnation of a fabric which contains rub-- ber distributed therethrough specifically with a thermoplastic stiffening agent, or the ening agent.

Signed at Cambridge, Massachusetts this.

twen -fifth da ofMa '1925.

ivmmdk. BOUGHTON.

product resulting therefrom, as this constitutes a prior invention made bv Charl s. E. Swett. now deceased. I do. however. claim as mv invention a two-step impregnation of a fabric with a gummy or elastic substance of the nature of rubber. and then with-a stiffening agent. like sodium silicate. and the product resultinq' therefrom. as disclosed in mv application Serial No. 641,767, filed May 26. 1923;

' I claim:

1. A composite fabric having, as

' gum-impregnated carrier she t and, com- -bined therewith throughout the bodv of the sheet and constituting the surface of the composite fabric, an agent possessing hardness and stiffness at ordinary temperatures, said composite fabric beinq characterized. by virtue of the elasticitv of said gum-impregnated carrier sheet and the hardness of said agent,

by a high degree of resilience and resistance to distortion.

2. A composite fabric comprising a carrier a base. a

sheet impregnated with a gummy hydrocarv bon related to the terpene series and coated and impregnated throughout with an agent possessing hardness and stifiness at ordinary temperatures, said gum-impregnated carrier sheet and said agent imparting to the composite fabric a high degree of resilience and resistance to distortion.

3. In the manufacture of 'shoe stifi'eners from fibrous foundation material, a process which comprises only partially saturating the fabric throughout with rubber to produce a porous rubberized fabric, and then filling