US3021240A - Flocked solvent activatable stiffener sheet material - Google Patents

Description

3,,fi2l240 Patented Feb. 13, 1962 3,021,240 FLOCKED SOLVENT ACTEVATABLE STIFFENER SHEET MATE Stanley M. Griswold, Newton, Mass., assignor to B. B. Chemical (10., Boston, Mass, a corporation of Massachusetts Filed June 1, 1959, Ser. No. 817,191 4 Claims. (Cl. 154-46) This invention relates to improvements in solvent-activatable sheet stiffener material and more particularly to improvements in flocked solvent-activatable stiffener material useful for stiffening and lining heel portions of shoes.

In my copending United States application for Letters Patent, Serial No. 847,550, filed October 20, 1959, there is disclosed a solvent-activatable sheet stiffener material comprising a layer of intermixed fiber and particles of a stiffening agent soluble at room temperature in an organic solvent. The layer is deposited by draining a furnish through a thin, relatively open fibrous sheet to which the layer becomes attached by interspersion of fibers. Upon treatment with such a solvent to coalesce the stiffening agent, the sheet subsequently hardens upon drying. Such material, when flocked on one side, is adapted to form the inner lining member of a shoe heel portion to provide a stiffening counterpocket member therefor having a pleasing appearance on the inside of the shoe.

It has been found that when circumstances permit careful handling of this flocked material in activated condition, very satisfactory results may be achieved. However, it was also found that shaping or stretching of a shoe portion containing the flocked material in activated condition, for example during conformation to the heel end of a last in the pulling over and lasting operations, was apt to cause difliculty in regard to wrinkling and distortion of the film of flocking adhesive carrying the flock. It appeared that upon activation of the material with softening of the fiber and stiffening agent layer by application of solvent, the flocking adhesive film was deprived of support, and being relatively weak, could readily stretch and wrinkle.

it is accordingly an object of the present invention to provide improved solvent-activatable sheet stiffener material comprising a layer of intermixed fiber and particles of a coalescible stiffening agent and a layer of flock held by a film of flocking adhesive, which material does not present the aforementioned difficulty.

According to the present invention, this difliculty is overcome by providing on the fiber and stiffening agent layer a firm resilient anchoring layer for the flocking adhesive film, which anchoring layer is not weakened by action of the activating solvent and which therefore provides at all times a firm base for the film of flocking adhesive which holds the flock.

The firm resilient anchoring layer of the present invention is provided by securing to the fiber-stiffening agent layer a sheet of cloth base coated with elastomeric material such as a rubber composition. The flocked film is disposed on the outside of this coated cloth anchoring layer and thus when activating solvent is applied to the other side, a firm base is preserved for the film by the anchoring layer. When limited stretching of the material is necessary, the stretching of the adhesive film and the stiffening agent layer is distributed or spread out more or less evenly by the anchoring layer along the corresponding dimension of the shoe element rather than occurring in local concentrations.

in the provision of a laminated solvent-activatable sheet material of the type provided by the present invention, it has been found that where the anchoring layer is adhesively bonded to an untreated surface of the layer of intermixed fiber and coalescible particles, the product is subject to delamination during handling prior to activation because of the weak support given by the crumbly surface of the latter layer. On the other hand, if this surface is first pretreated with suflicient solvent to coalesce the particles over the entire surface of the layer with partial coalescence extending through a depthwise portion of the sheet, while a relatively firm attaching base is secured, it has been found that such preactivation with solvent renders the sheet too stiff for shoemaking and interferes with subsequent complete solvent activation of the layer by causing the partially but incompletely activated areas to become resistant to effective softening by solvent activation. Consequently, the ultimate stiffness of the material is less. It is believed that the reduced capacity of the partly activated material to be solvent activated is a combination of reduced access through partial closing of porosity, and less favorable contact conditions, e.g. the smallest particles will have been coalesced and rough surfaces rounded off.

Accordingly, it is another object of the invention to overcome the aforementioned difiiculty and to provide a laminated solvent-activatable stiffener sheet of the foregoing type having superior strength of the laminating bond without adversely affecting subsequent solvent activation.

To this end and in accordance with a feature of the present invention, there is provided solvent-activatable sheet material comprising a layer of intermixed unwoven fibers and coalescible particles of stiffening agent laminated with a firm resilient anchoring layer carrying a film of flocking adhesive and flock in which a portion of the fiber-stiffening agent layer has been preactivated by application of solvent to fractional, at least semi-isolated, areas. Such preactivation may be achieved by spattering the untreated surface of the fiber-stiffening agent layer with a limited amount of solvent, or as hereinafter more completely described, by application of a limited amount of solvent with a knurled roller in the absence of substantial pressure.

It has been found that such treatment produces in the material beneath the areas of activation partial fusion of the stiffening agent particles in an incursive formation narrowing in cross section depthwise of the material. These formations provide a root for extending depthwise delaminating stresses between the material and another layer bonded to its surface, render the material firmer (but not too firm for shoemaking) so that areas of a counterpocket which cannot be reached with solvent, for example, the heel top, are adequately stiff, and improve the cutting characteristics of the material to give cleaner edges.

With this form of preactivation, the activating solvent has access through untreated portions of the material through its entire depth or thickness and can activate such portions entirely, while contacting the formations from all sides to produce at least partial activation therein. Thus the ultimate stiffness of the material after activation is not substantially impaired by the preactivation treatment.

Other features and advantages of the invention will best be understood from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a greatly enlarged partial section of a sheet of solvent-activatable stiffener material embodying the present invention; and

FIG. 2 is a horizontal section taken on line 11-11 of FIG. 1.

Referring to FIG. 1, the numeral 10 designates a layer of intermixed unwoven fibers 12 and particles 14 of a normally solid stiffening agent soluble at room temperature in an organic solvent. Suitably the fibers 12 may be kraft paper pulp fiber While the particles 14 may be polystyrene either ground or advantageously in the form of small beads as produced by suspension polymerization. In either case, the polystyrene will be seived to size exemplified in the case of beads by a size distribution in which no beads are larger than 0.047" in diameter (16 mesh) and 50% by weight are smaller than 0.007" in diameter. As described in greater detail in the abovementioned application, hereby incorporated by reference, a furnish, comprising 2 to 2 /2 parts by weight of the resin and one part by weight of pulp filber in water to make a suspension of about .04% or less solids, is drained through a thin, relatively open fibrous sheet 16 to deposit the solids in the form of the layer 10, interspersion of the fibers of the layer 10 and the sheet 16 at the interface holding the layer and sheet together in an assembly when dry, the assembly being then rolled to compact it, for example, from about 0.040" to about 0.025 in thickness.

In accordance with the present invention, one side of the assembly, preferably the side surfaced with sheet 16, is bonded, by means of a suitable adhesive 18 not harmed by the activating solvent, to a firm, resilient anchoring layer 20 comprising a sheet of cloth 22 base coated with elastomer 24, such as a rubber composition.

Prior to the bonding of the layer 20 to the assembly comprising the layers 10 and 16, the bonding surface of the assembly is preactivated as described hereinafter and conveniently the layer 20 is flocked, whereby a film 26 of flocking adhesive carrying partly embedded therein flock fibers 28 is provided over the base coat of elastomer 24.

The cloth used for the purposes of the present invention will be chosen primarily with respect to the end use of the sheet stiffener material and with regard to its cost and can be practically anything so long as it has adequate strength and, with heavy cloth where the appearance of a cut edge is material, the impregnation is heavy enough to prevent the showing of a frayed edge. For the purposes of providing a flocked counterpocket element, the cloth suitably may be print cloth of from about 8.60 to about 5.50 weight, meaning that, respectively, 8.60 yards and .50 yards of the cloth weight one pound in the 38 /2 width.

The elastomer composition may comprise natural or synthetic rubber, reclaimed rubber or substantially any other elastomeric polymer curing or non-curing which will not be harmed by the activating solvent.

One suitable curing formula is as follows:

Parts by weight The elastomer composition may be applied to the cloth by calendering or by softening the composition with solvent and spreading it on the cloth. Thereafter, the cloth carrying the elastomer composition is heated to cure the latter and, after a sufiicient coating has been applied flocked in the conventional manner.

Flocked elastomer coated cloth suitable for use in the present invention is also available from a number of commercial sources.

In the preferred form of my invention, prior to laminating the anchoring layer 20 to the layer 10-layer 16 assembly, a portion of the bonding surface of the latter is treated in a preactivation step by the application thereto of a limited amount of solvent in fractional, at least semi-isolated, surface areas. Such preactivation may be accomplished by spattering the surface of the layer 10 opposite the layer 12 with solvent by means of a brush. More conveniently, however, solvent may be applied rapidly to a large area by passing the assembly of layers Mineral oil 4 10 and 12 bonding surface down between two rolls in the absence of any substantial pressure, the lower roll being knurled and dipping into solvent. If, for example, the lower roll has a deep diamond knurl and the material is run slowly between the rollers, the knurled roll will pick up a limited amount of sovent which will be deposited as if in the form of drops in circular surface areas centered at spaced locations on the surface of the assembly, a certain amount of overlapping of such areas taking place. The amount of solvent deposited will depend upon the speed of rotation of the knurled roller and the depth of the knurl. These should be so related that just enough solvent is applied to the surface of the assembly to wet out only such fractional areas. It has been determined, by weighing the treated material immediately after its passage through the rolls, that about 2 ounces of toluol per square yard is a suitable quantity whether applied overthe sheet 16 or not, since the amount held inactive by the sheet 16 is negligible.

This treatment produces, extending beneath the semiisolated circular surface activation areas, incursive formations 30 of partial coalescence. Other activation patterns, e.g., linear, herring bone, or small rectangles, may be used.

The assembly may then be dried and laminated to the flocked anchoring layer 20. For this purpose it is convenient to apply to the partially preactivated surface of the layer 10 a bonding adhesive 16 which may suitably be a natural rubber or neoprene latex composition with tackifying resin dispersed therein, and to combine the parts while the latex is still wet. The laminate is then allowed to dr An example of the present invention in its preferred form follows:

Example A sheet of 8.60 print cloth was base coated with the elastomer composition described above. The coating was heat cured and a second coating was applied and heat cured to provide an anchoring layer of approximately .005 thick. A flocking adhesive was applied over the coating and flock was applied in the conventional manner followed by heat curing of the flocking adhesive.

A fiber-stiffening agent sheet was made by straining, through an 8" x 8 sheet of relatively open, non-woven, rayon fabric about 3 /2 mils thick and weighing about 8 grams per square yard, an aqueous furnish comprising 10 grams of kraft paper pulp and 25 grams of polystyrene beads (less than 0.047, 50% less than 0.007" in diameter) in 750 cc. of water. The sheet was dried and then rolled from about .040" to about 0.25 thickness. The sheet was then passed slowly, fabric side down, between two rolls, the lower of which was formed with a deep diamond knurl and dipped into a pan of toluol. During passage of the sheet between the rolls, the lower roll deposited solvent on the lower surface of the sheet in relatively small circular spots. Under drying of the sheet, this surface presented a dappled appearance resulting from the coalescence in partial areas of the surface of the polystyrene beads. On cutting the sheet and inspecting the edge it was seen that partial coalescence extended depthwise under such areas. A coating of 45% solids neoprene latex composition (No. 810 BeBeTex, B. B. Chemical Co., Cambridge, Mass.) was painted on the fiber-stiffening agent on the sheet over the preactivated surface and while this composition was still wet the flocked anchoring layer was pressed over the composition.

After drying the laminate was died out in the form of a counterpocket, skived, and attached to a quarter by forming a seam. at the top of the heel portion. An activating solution comprising a 50-50 (parts by weight) naphtha-toluol mixture was applied to the fiber-stiffening agent layer (the unflocked side) and the upper was subjected to pulling over and lasting to an insole. After drying, it was found that the heel portion of the shoe was satisfactorily stiffened with no wrinkling or breaking of the flock coat and with a satisfactory top appearance and side graduation.

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

1. As an article of manufacture, a laminated sheet comprising a layer of intermixed non-woven fibers and particles of a coalescible stiffening agent and a firm resilient anchoring layer of elastomer coated cloth adhesively bonded thereto.

2. As an article of manufacture, a laminated sheet comprising an assembly of a layer of intermixed nonwoven fibers and particles of coalescible stiffening agent and an anchoring layer of elastorner coated cloth adhesively bonded thereto, the elastomer coat carrying a layer of flock partly embedded in a film of flocking adhesive.

3. As an article of manufacture, a laminated sheet comprising a layer of intermixed fiber and particles of coalescible stiffening agent and an anchoring layer of elastomer coated cloth adhesively bonded thereto, a por tion of the surface of the fiber-stiflening agent layer ad- References Cited in the file of this patent UNITED STATES PATENTS 1,720,764 Silvester et a1 July 16, 1929 1,991,464 Mellerio Feb. 19, 1935 2,256,034 Notteba'hm Sept. 16, 1941 2,317,595 Faris Apr. 27, 1943 2,494,848 Whatelezg Jan. 17, 1950 2,616,821 Harrison Nov. 4, 1952

Claims (1)

1. AS AN ARTICLE OF MANUFACTURE, A LAMINATED SHEET COMPRISING A LAYER OF INTERMIXED NON-WAVEN FIBERS AND PARTICLES OF A COALESCIBLE STIFFENING AGENT AND A FIRM RESILIENT ANCHORING LAYER OF ELASTOMER COATED CLOTH ADHESIVELY BONDED THERETO.

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