US2192934A - Shoe filler composition and method of making - Google Patents

Description

Patented Mar. 12, 1940.

UNITED STATES PATENT o 'FFI-C Ernest D. Sackett, West Somerville, Mass:, as-

signor of one-half to NortmAmericanfHolding CorporationySyracuse, N. Y.', a corporation of New York, and one-halftowParshad Holding Corporation, Syracuse, N. Y., a corporation of New York No Drawing. ApplicationDecernber 5, 1936,

Serial No. 114,452 11 Claims. (oi; 106-3) This invention relates to shoe filler compositions and to a method of preparing the same.

In the art of making filler compositions for shoes, it is necessary that many varying requirements of the shoe-making industry shall be served, at least as nearly as may be possible. To this end, many considerations must be taken into account, and necessarily they will find their solution only in the provision of numerous conditions and properties in the appropriately developed shoe filler composition which is to meet such requirements satisfactorily, in any given case.

For example, before the assembly of theouter sole of a shoe with the already assembled upper and inner sole (which are at this stage already stitched together) it is now customary with some shoe manufacturers to apply the shoe filledcomposition to the under side of the inner sole,

spread it somewhat by hand and then to finish the spreading operation by machine.

The partly constructed shoe, atthis' stage of its manufacture, consists of the upper, which is drawn over a wooden last and sewed around its:

The

loweredge to the edge of the inner sole. latter is usually tacked'to the bottom of the last before sewing. After sewing the tacks are with drawn, and the sole portion is ready to receive the filler composition, which serves the purpose of lining the cavity formed by the stitched edges the supply mass is subjected, directly or indirectly as the case may be to a current of steam which softens the composition and develops the required consistency for spreading. The lasted shoe is held in the hand of the operator, in an inverted position, an estimated-amount of the filler taken from the mass on a spatula, applied to the cavity of the shoe bottom, and spread for-- ward and back somewhat, to correspondto: the size and shape of the cavity. In the complete further hand method the composition is" smoothed off and finished by hand. In the machine method, however, the operator atthis'stage? -,,inserts the shoe into a-press, in which a reciprov spreading, which is done entirely by hand, using j tion laterally and outwardly in all directions'tofill the cavity and penetrate into andfill all the grooves and depressions, but more particularly.

alongthemargins of'the cavity formed by the stitched seam between the inner sole and upper. It'also smoothsofi the top surface of the filler composition to'a' fiat, firm, substantially smooth and continuous surface (corresponding to the contour of the shoe, and as determined by the shape and contourof' the presser plate) upon which the outer sole is subsequently laid and firmly attached by stitching and adhesive attachment to the filled composition, promoted by subsequent compression and molding of the assembled shoe.

While the oscillating presser plate moves steadily and'fairly rapidly up and down and is adapted to exert a pressure of some 300 pounds per square inch upon the bottom of the shoe as it descends, it does not have the repercussion effect of 'a sudden'blow, because its length of stroke and speed of movement are restricted, and

the supporting roller also is-made to yield, which has the effect of prolonging and gradually increasing 'thepressure. The plate surface is sufiiciently large to overlie the forward portion of the sole, and in" some'casesthe instep portion also, when filler composition is used in sufficient in all directions; Preferably, Whether the deposit has already been spread out or is left heaped up locallyas applied, the displacement is substantially instantaneous and the principal tendencyis for the charge as a whole to be dispersed laterally, rapidly, and at greatspeed and pressure; This carries thecomposition forward into the toe portion, sidewise into the grooves and pockets of the sewed seam between the inner sole and upper, into intimate: contact with the entire underside of the inner sole, and rearwardly over 'flow as above described. But since such binder "ponent was taken 'up by the fluid binder and It therefore follows, that under this quick pressure, the composition should be able. to now freely and uniformly in all directions, but cor-- responding to the pressure applied. It should not flow either before the pressure'is applied or after it has been discontinued. And it should not exhibit any tendency to adhere to the presser plate, or be lifted up by suctionr At the same time it is essential that it cohere under pressure suficiently to preserve its form and disposition in the shoe and adhere to the shoe surfaces and subsequently to the outer sole which is to be applied over it later. And it should possess this cohesiveness and adhesiveness throughout the life of the shoe, sufiiciently to maintain the filler composition intact, in the form and shape imparted to it, and remain firmly positioned within the shoe structure permanently.

Heretofore, in preparing shoe filler compositions for use in the hot press method of making shoes, it' has been customary to use a relatively large proportion of fluid binder material, so that under the press and while hot it should be free to vehicle or to float the solid particles past or over one another. Consequently such compositions would not undergo flow under compression, but

lump up into an unworkable hard mass, which would be consolidated only by the compression,

and expand thereafter, and not be subject to spreading by machine.

Accordingly, to overcome these difficulties, the

practice was adopted to 'mix the comminuted granular body material with a'suflicient amount permit of fluid flow of the mass as a whole. 'And in "addition to this mixture there was employed a large, controlling proportion of fine material, such'as cork dust or fines, or the like, which was equal to at least one third, by volume, of the granular body material itself. This comcarried throughout the mass. It did not prevent the fluid binder'from serving as a vehicle for thedispersion of the composition as a whole when put under compression. But during compression, as well as before and after compression, its presence in the fluid binder impeded. the movement of the granules of body material and rendered the liquid portion of thev mixture more or less resistantto spontaneous flow and segregation from the comminuted solids, by gravity, for example, or during the spreading operation.

Such compositions, therefore, presented. the system of a, mixture of coarsely comminuted. solid bodies carried by :an excess .of a liquid, .viscous vehicle, the inherent mobility of which was restricted by a large volume of entrained finely divided solids, sufficient to check the tendency oii the excess of the liquid binder to manifest fluid flow. But it did not render the mass truly: plastic and subject to dependable plastic flow, but rather and impeded liquid flow.

Obviously this was a very nicely balanced relationship in which the prevailing condition of the mass as a whole was directly dependent upon (a) the amount of fluidbinder material or vehicle in excess of the amount required to fill the spaces between the comminuted granular material and act as a vehicle; and (b) the amount of .dust added thereto to check its free liquid flow without overcoming the fluidity to such a degree as to prevent flow under pressure.

of fluid binder thereto. But when the binder is fluidand when'it is present in suflicient amount to'form continuous contact with the body material, it shows a tendency to penetrate and fill the body material, thus making the body material heavier, and altering the effective proportions of the fluid binder as a vehicle, and the comminuted solid body material. In softening the mixture with steam, the cork granules and dust take up some of this condensed water. If the water is present in excess and not taken up, it will squirt out of the filler, when subjected to pressure, with obvious deleterious consequencesboth to the operator and to the deposit of filler composition left in the shoe.

It follows, therefore, that it has been difiicult to make shoe filler compositions upon this basis whichwould exhibit uniform flow and dispersion in the hot press method of filling shoes; and also that it has been difficult to make successive batches of the composition which would exhibit the same properties, even when the assembling and filling operations, in the manufacture and filling of shoe bottoms therewith, were constant.

Moreover, the shoe filler compositions which have been provided for use in the not press operations of manufacturing shoes, have necessarily been characterized by a high proportion of binder, the incorporation of a large amount of dust, and a resultant relatively heavy product, and

though plastic and spreadable when heated, sub-- ject to Variations in properties during preparation and when subjected to pressure.

It is therefore an object of the present invention to provide a method or making shoe filler compositions which shall avoid the difficulties and irregularities of the prior art, and yield a type of shoe filler composition which may be uniformly prepared and applied, either by hand or in the hot press method of assembling and filling shoes, with greater uniformity of operation and of properties, in use, and thereafter in the finished shoes obtained. Further objects will appear from the following disclosure.

By the present invention it is round that shoefiller compositions may bemade for use in the hot press method of assembling shoes, by combining the comminuted solid body material with a low proportion of binder material, and with a slipperyfiinorganic plastic component of gelatinous or jelly-like consistency, which isnot liquid 7 will flow uniforrnly and-quickly under pressure or heat and pressure, and which will maintain the positionand distribution of the filler in the finished shoe.

The invention accordingly includes'a method of preparing a shoe filler composition and the shoe filler composition itself, which, when subjectedto the action of heat'and moisture, develops a truly plastic slippery medium which in turn makes spreading possible-both by hand and in the press. Another characteristic of the composition is that its free plastic flow disappears abruptly when differential pressure is discontinued. A further characteristic is that the plastic .into other parts of the shoe.

component may contract in volume and lose its plasticity, after application to the shoe, as by drying.

As a body material for the fillercomposition, a rather coarsely comminuted granular solid is employed, the individual granules of which preferably preserve a considerable degree of toughness and resiliency. Other materials are suitable, and may be used, but granulated cork, of a size between 20 and 30 mesh, is usually preferred.

Such granular cork is very light and occupies a great volume relative to its weight. For example, 11.5 grams will occupy a volume of 160 c. c., of which approximately c. c. or more represents the voids between the granules and pore space within the granules. Since the mass of cork granules thus exhibits an ostensible specific gravity of about 0.07 and an individual specific gravity of about .12, it will be manifest that if the voids, between them are filled with relatively heavier binding material, it will require a weight of such binder which is many times the weight of the cork, in order to fill such voids.

But while it is necessary to more than fill the voids between the cork granules, if a viscous fluid adhesive binder is employed, as above pointed out, in order for the mass as a whole to exhibit fiow under pressure, such a proportion is not necessary if the binder consists of or contains an effectively plastic vehicle. Heretofore, the ve hicles used were liquid and Were absorbed by the granular material and if used in large amounts continued to render the filler permanently fluid and hence mobile after deposition in the shoe, so that it would shift or bunch up or penetrate For this reason, the amount of such binder which could be used, while necessarily large, was nevertheless limited to such an amount as wouldbe effectively restrained by its viscosity and the friction of the granular body material. Consequently, as above pointed out, the total amount of binder required was excessive and itself required further restrainpowder form or more or less fluid, or rendered so effectively by moderate heating, the presence of solvents, or by dispersion in the plastic gelatinous component, etc. It may be of a composition adapted to undergo setting, or may not, as desized, and yet serve satisfactorily. It may contermining the consistencyof the mass.

left in thefinished shoe.

tribute to the fluidityof the mass and usually will do so to a greater or less extent when hot (as when softer materials such as wax tailings are used in the binder component), but this is not essential, since this factor is primarily provided for by the plasticizer component (bentonite), as hereinafter described.

The adhesive binder and addition agent or plasticizer maybe mixed in such a way that the adhesive predominates and the addition agent is dispersed therein in dispersed phase. In this case the adhesive is in continuous phase and thus adapted to effect continuous contact with the walls of the shoe cavity, in which it is deposited, and with the surfaces of the granules of commi nuted solids or body material. In such proportions the dispersed plasticizer is effective to lubricate the binder-coated granules and also fresh surfaces of the mixture such as those formed by cutting the mixtures and spreading or working the mixture with a spatula, as is done in the application of shoe fillers, as above described. Especially is this the case when the plasticizer is hydrophilic or hydroscopic and the mass is soitened with steam or hot water.

If the adhesive binder and plasticizer are in balanced phase or the plasticizer prevails as continuous phase, its plastic qualities will dominate over the adhesive qualities of the binder in de- But since under these conditions the plasticizer will ordinarilybe the more mobile it will spread more readily thus leaving the more viscous or resilient particles of adhesive to attach themselves to the granules and both will accordingly receive greater pressure from the spreading tool or presser plate, without movement or escape, and this will force them into closer contact and thus develop their adhesiveness still further. Such adhesion, however, will be in the nature of localized points or spots, rather than present-the continuous contact and resistance of the viscous adhesive when present in continuous phase. This type of adhesive contact presents some advantageous features as will be pointed out below.

A feature of the plasticizer herein employed is that it does not itself contribute appreciable adhesiveness, on the one hand, nor interfere with the adhesive properties of the adhesive binding agent, which is combined with it, on the other. A further advantage is that, after exercising its plastic effect in the shoe filler composition at the time of its application to the shoe and especially when subjected to compression by the presser plate, it loses such plasticity upon being For, when the shoe is completed, the filler composition therein dries somewhat and the plastic component loses a considerable portion of its moisturev and plasticity. Accordingly, since practically all of the plasticity is attributable to the plastic addition reagent, when in its original or remoistened condition and while holding the binder and granular body material in dispersion, the bonded granular material is effectively set when the plastic addition reagent becomes non-plastic.

ihe plastic addition agent employed is typ ically composed of finely divided inorganic compounds such as hydrous oxides or salts, or both, which are capable of ready absorption of water, to swell appreciably and form a jelly-like mass usually of increased volume, and of pronounced plastic, smooth, thin, film-forming consistency; and which are also susceptible of drying out and resuming their finely divided, non-plastic, discrete condition as a powder, or an intermediate, more or less hard or tough consistency. A typical and preferred material suitable for this purpose is bentonite clay, which is generally considered to be composed of individual particles, of colloidal dimensions and somewhat larger, which are extremely thin and flat, of micaceous characteristics, (e. g., in presenting particles of appreciable dimensions in two directions but extremely small proportions in the third) but highly absorptive of water, the hydrous product occupying many times the volume of the dry material, presenting a smooth jelly-like consistency, homogeneous in all directions and manifesting free and uniform flow in all directions, under slight pressure, but self-sustaining under its own weight.

Such material is ideal for the purpose of the present invention, as an addition agent to disperse the binder component or components of the filler composition and imparts thereto both superficial and internal lubrication and free fluidity, under slight difierential pressure, of the mass as a whole. This is true, even when the addition agent is present in subordinate proportions, relative to the adhesive component or granular body material, or both, for the reasons given above. It consequently lubricates the spreading knife used in mixing the mass, scooping out the required quantity and applying it to the shoe bottom and spreading it about as required, under light pressure. This is important for, as will be clear to the operator, it permits of completely applying, spreading and smoothing .ne composition in the shoe bottom, as a hand operation, if desired.

In the hot press method of applying the filler, as more particularly described above, however, the filler composition is first applied to the shoe bottom in sufficient amount and distributed somewhat by hand, so as to be apportioned over the several portions of the shoe bottom, or left in a single mass as deposited. The shoe is then put into the press, and the composition subjected ;to the pressure of the presser arm and plate, as

already described. Thereupon the filler composition manifests true plasticity and plastic flow and flows freely and instantaneously over the remaining, uncovered part of the shoe cavity, into intimate, pressure contact therewith, penetrating all of the irregularities of the shoe structure. The charge as a Whole is compacted into a firm, adhesively bonded mass, in which each of the solid granules is intimately contacted with and surrounded by the binder and thus to each other and to the shoe, in a continuous structure. But an outstanding characteristic of such composition is that the fluidity of the liquid adhesive binder material is not relied upon for such application and distribution. Hence the binder may be used in such reduced proportions that the composition is, in respect of relative volumes, substantially entirely composed of the granular body material such as cork, the binder being contained in the interstices and'even there, in this adherent films only over and between adjacent surfaces of the granules and between the granules and the shoe surfaces. The remainder of the volume of the composition, (i. e., the

interstices between the binder-coated granules) may be made up of the jelly-like menstrum of the plasticizer or addition ingredient, which while not fluid under its own weight flows freely and serves as a vehicle for the binder and granular body material mixed with it, under pressure (and.

amassemore or less proportioned to the differential or shearing pressure applied) and again ceases to flow when the pressure is released.

As the adhesive binder in such compositions, rosin, or resinous materials generally may be used, and either alone or with the addition of softeners thereof such as petroleum, castor oil,

factice, etc., and with Wax tailings, high melting petroleum residues or the like. Certain oxidized or distilled products of the extraction of wood which are adhesive and suitable for dispersion therein, may also be used.

A typical and representative shoe filler composition may be prepared as follows:

24 pounds of soft wax tailings and 15 pounds B rosin (180 F. melting point) are melted together and cooled to approximately 100 C. There is then added in succession and with rapid agitation 1 pound of oleic acid (or other saponifiable organic acid which will serve as an emulsifying agent) /5 pound of caustic soda, in water solution, and a hot paste of pound of bentonite in 8 pounds of water. When homogeneous, this mixture is poured into a charge of 11 pounds of granular cork of a mesh size between 20 and 30, and the mixing continued until the binder composition and cork granules are uniformly dispersed. Increased flexibility of the filler composition may be obtained by adding appropriate quantities, e. g., up to about 2 lbs. in the foregoing formula, of such softening agents as castor oil, rosin oil, or like softening agents for the binder component.

The amount of water used may be varied more or less at will. In the proportions here recited the heat of the charge may be sufficient to evaporate a considerable part or nearly all of the water present. It is possible, though not so convenient, to add the bentonite in dry condition. In either case, the reduction or elimination of moisture is effective in reducing the weight of the composition for shipment to the place of use. It is then heated, usually by steam, which is applied directly or indirectly or both, and frequently water in addition to condensed steam is added to the mixture. This not only softens or melts and disperses the binder but also moistens and causes the bentonite clay to swell and resume its plastic, gelatinous or jelly-like consistency throughout the mass, still further to promote and maintain such dispersion.

While, for some of the purposes above described the bentonite paste may be added without the oleic acid and caustic soda, these ingredients react to form soap which promotes emulsification of the adhesive, and'also renders the plastic jelly slippery (as well as plastic) under compression. It is therefore an advantageous addition.

In view of the fact that filler compositions, when heated for application to the shoe, are also kept moist and free from burning by the addition of water and/or condensation of steam, there may be a tendency for this water to be expelled from the shoe bottom, when subjected to compression under the presser plate, somewhat analogous to what occurs when too much fluid adhesive binder is present, as above described. To offset this effect, a relatively small proportion of cork dust, e. g., cork ground finer than 30 mesh, may be incorporated in the mixture. This becomes associated with the aqueous bentonite jelly and when the water or steam is subsequently added checks its tendency to flow, during application and under the pressure plate.

But it is to be noted that the water or condensed skill of the operator.

steam of the mass heated by these materials is thus checked :by theplastic bentonite jellycand cork dust rather than fluid flow of the adhesive binder composition by cork dust. The bentonite jellyis truly plastic and undergoes plastic flow accordingly, in. contrast to the viscous liquid flow, characteristic of the hot filler compositions of the prior art. When the mass is carefully heated by steam, and an excess avoided the expulsion of water is notencountered. But when both steam and liberal amountsof water are added by the operator, the amount of granular cork may be slightlyreduced (e. g, to 10 -poundsin the above formula) and upto 2 pounds of cork dust added inplace of thereduction'of cork. This is a smaller proportion of dust than'the minimum heretofore used in such compositions.

After application to the shoe, spreading by hand or by means of the presser plate, or both, the composition is both formand position-retaining, adherent to the shoe bottom, of uniform consistency, and light in weight. The overall volume of the granular cork substantially equals the volume-of the shoe cavity so that any tendency to shift subsequently is minimized or eliminated. The cork granules, severally coated with adhesive, are joined to each other and to the shoe. At this stage they are embedded in the gelatinous or jelly-like matrix of the hydrated bentonite. Upon subsequent evaporation of water, however, there is no tendency to alter their distribution. The gelatinous matrix simply contracts between the adherent mass of granular solids which are left, closely packed, in situ; air takes the place of the water, leaving a porous, tough, integrated mass. held in the shoe cavity and adapted to cushion the tread portion of the shoe under the foot of the wearer.

It is a feature of compositions of the type herein described that they are adapted to accommodate wide variations in the character of the comminuted body material employed.

For example, it is well known that, in reducing soiids to granular or pulverized form, the resulting granules are infinitely varied, both in size and shape. It is true that standardized equip ment, uniformly operated, with a constant supply of dependable raw material, will yield an approximately average overall product. But if this granular product be subjected to a size analysis, as by screening, it will be found that the absolute mesh sizes, and the relative quantities obtained of each will vary constantly. This is the case with sawdust, ground cork, and the like, which is used in shoe filler composiions. And, when these materials are mixed with viscous fluid binders, of the prior art, the sizes of the filler particles and the relative amounts of each size are of firstimportance in affecting the consistency of the composition. It is largely in consequence of this fact, that it has been customary in this art to adjust the proportions of the filler and binder in terms of the consistency actually developed in each case, adding more of one or the other as determined by the observation and But such observations and adjustmentsare susceptible to error and lead to the manufacture of a product which will give variable results in use, even with the exercise of the greatest care.

In the composition herein described, however, while the granular body material becomes associated with the binder and may present some variations in respect of this relationship, nevertheless the binder does not appear to be appreciably absorbed-by the granular body material. Moreover, when the binder is first mixed with the plastic component and mixed therewith, this x dispersed conditionstronglyrestrains its penetration of the body material granules and hence I preserves the consistency of the mass. The body material, fine or coarse, porous or dense, becomes immersed in the plastic jelly and binder, and is contacted or wetted by both, but is not penetrated by either. Thus the presence of the granular usolids or-dust particles in the mixture, perhaps because they are not surrounded by the small viscous fluid binder globules 0n the one hand or because the jelly-like plastic component does not flow around them, on the other, does not affect appreciably the plastic consistency of the mass was awhole, in terms of particle size, but primarily overall average range of comminuted material to the plastic vehicle to be employed with it, and the vehicle, in turn, is made up of the plastic component and the binder component in terms of their respective contributions to the consistency of the vehicle as such. After once establishing the desired proportions for a given set of considerations, to take into account the materials, operations, and conditions involved, these proportions may be maintained, substantially without further estimated adjustments, corrections, or modifications, by the operator who makes up the composition, even though the comminuted material vary considerably in the mesh sizes which it contains.

I claim:

1. Method of preparing shoe filler compositions, comprising mixing and heating a thermoplastic water-insoluble adhesive, a minor proportion of bentonite, water, and a comminuted granular body material.

2. Method of preparing shoe filler compositions, comprising mixing and heating a thermoplastic water-insoluble adhesive, a minor proportion of bentonite, water, an emulsifying agent, and a comminuted granular body material.

3. Method of preparing shoe filler compositions, comprising mixing a thermoplastic water-insoluble adhesive in fluid condition, a minor pro- I portion of dry bentonite, and a comminuted granular body material.

4. Method of preparing shoe filler compositions, comprising mixing a thermoplastic water-insoluble adhesive in fluid condition, a minor proportion of .drybentonite, an emulsifying agent, and a comminuted granular body material.

5. Method of preparing shoe filler compositions, comprising the steps of mixing a comminuted granular material with a thermoplastic waterinsoluble adhesive and a minor proportion of bentonite, and thereafter subjecting the mixture to heat and moisture, thereby to soften the thermoplastic adhesive, swell the bentonite and render the mixture plastic.

6. Method of preparing shoe filler compositions, comprising the steps of mixing a comminuted granular material with a thermoplastic waterinsoluble adhesive, a minor proportion of bentonite, and an emulsifying agent, and thereafter subjecting the mixture to heat and moisture, thereby to soften the thermoplastic adhesive, swell the bentonite and render the mixture plastic.

7. A shoe filler composition, characterized by containing a thermoplastic water-insoluble adcontaining a thermoplastic water-insoluble adhesive, a minor proportion of bentonite, and a comminuted granular body material, in intimate admixture.

10. A shoe filler composition, characterized by 5 containing a thermoplastic water insoluble adhesive, a minor proportion of bentonite, an emulsifying agent, and a comminuted granular body material, in intimate admixture.

11. A shoe filler composition, characterized by 10 containing a comminuted body material, a thermoplastic water-insoluble adhesive, a minor proportion of bentonite, insufficient to fill the voids between the comminuted material when dry,

but sufiicient, when heated and swollen with 5 water, to render the composition plastic.

ERNEST D. SACKE'I'I.