US3102836A

US3102836A - Sheet material comprising fibers and plastic particles

Info

Publication number: US3102836A
Authority: US
Inventors: Stanley M Griswold
Original assignee: United Shoe Machinery Corp
Current assignee: United Shoe Machinery Corp
Priority date: 1959-10-20
Filing date: 1959-10-20
Publication date: 1963-09-03
Anticipated expiration: 1980-09-03

Description

p 1963 s. M. GRISWOLD 3,102,836

SHEET MATERIAL COMPRISING FIBERS AND PLASTIC PARTICLES Filed Oct. 20. 1959 3 Sheets-Sheet 1 [3 fnverzfor Szfarzley M Griswold B his Afforney p 1963 s. M. GRISWOLD 3,

SHEET MATERIAL COMPRISING FIBERS AND PLASTIC PARTICLES Filed Oct. 20, 1959 3 Sheets-Sheet 2 Inv enior Sfanley M Griswold By his Ahorn P 1963 s. M. GRISWOLD 3,102,836

SHEET MATERIAL COMPRISING FIBERS AND PLASTIC PARTICLES Filed Oct. 20. 1959 3 Sheets-Sheet 3 United States Patent 3,102,836 SHEET MATERIAL COMPRISING FIBERS AND PLASTIC PARTICLES Stanley M. Griswold, Newton, Mass, assignor, by mesne assignments, to United Shoe Machinery Corporation, Flemiugton, N.J., a corporation of New Jersey Filed Oct. 20, 1959, Ser. No. 847,550 5 Claims. (Cl. 162-198) This invention relates to improvements in sheets of fibers intermixed with coalescible particles of plastic and particularly in solvent-activatable stiffener material for stiffening end portions of shoes and the like.

This application is a continuation-in-part of my copending United States application for Letters Patent Serial No. 776,525, filed November 26, 1958, entitled Solvent Activatabie Stiifener Material and Method of Making Same, now abandoned.

In the past, it has been common to stiffen end portions of shoes by incorporating in a selected portion of the upper prior to lasting, a blank died out of sheet material which, wetted with a volatile solvent, is flaccid until, upon drying out, it becomes resilient, whereby the lines of the last may be preserved in the finished shoe. Typically such shoe stiffener sheet material comprises a textile fibrous base having incorporated therein in discontinuous form a normally solid stiffening agent soluble at room temperature in a volatile organic solvent so that while the sheet material is initially flexible to a degree permitting certain manipulations such as sewing room operations, it may be activated, i.e. wettccl out with a solvent, to cause the material to become flaccid and subsequently to dry out with the stiffening agent coalesced, thereby causing the material to become resilient.

Textile base sheet stiffener material is relatively expensive in contrast with sheet material employing a nonwoven fibrous base. Accordingly, there have been continuing efforts toward the development of solvent activateble stiffener materials employing a non-woven base. One approach to an inexpensive solvent activatable stiffener material has involved using the technique of paperm aking. Thus a number of different types of porous water-laid sheet material of fiber and coalesciblc particles of plastic stiffening agent, such as one comprising fiber and cellulose nitrate powdered, have been proposed. However, such developments met with a number of difficulties, both with the product and with the process of making the sheet ma terial. If the stiffening agent was combined with the fibrous material in particle form, e.g. powdered, coarse particles of stiffening agent tended to clog the screen of the papermaking machine so that in time its porosity became seriously interfered with, while finer particles tended to pass through the screen with consequent loss of stiffening agent in the white water removed during formation of the sheet. These factors also affect the uniformity of the thickness and distribution of the components of the sheet.

An object of the present invention, therefore, is to provide economical water-laid sheet material comprising fibers and coalescible particles of plastic which will have low material cost and superior uniformity.

To this end, and in accordance with a feature of the invention, sheet material is provided comprising a layer of felted fibers incorporating coalescible particles of a plastic, the plastic being, for shoe stiffening purposes, a normally solid, resilient stiffening agent soluble at room temperature in a volatile organic solvent, and a relatively open fibrous fabric on at least one face of said layer of felted fibers, fibers of said layer and said fabric being interspersed at the interface. Preferably, for economy, the fabric may be a non-woven fabric. This fabric, at-

3,102,836 Patented Sept. 3, 1963 tached to the felted layer by such interspersion of fibers, strengthens the composite sheet and minimizes disintegration from its face thus providing enhanced cleanliness. Further, this means of attachment comprising the interspersed fibers permits solvent readily to penetrate through the interface, for example, in solvent activation.

It has also been found that in the shaping or stretching of a shoe portion containing the material in activated condition, for example during conformation to the heel end or toe of a last in the pulling over and lasting operations, some difficulty may be encountered due to tearing or breaking of fiber stiffener material particularly with lasts having relatively sharp angles such as, for example, toe portions of lasts for wall toed shoes.

It is accordingly an object of the present invention to provide improved solvent activatable sheet stiffener material which is resistant to damage when used in shoes which are lasted over sharp angles of lasts.

To this end, and in accordance with a feature of the invention, this difficulty is overcome by providing a lamihated sheet including a layer of intermixed fiber and coaiescible particles of a solvent soluble stiffening agent, a layer of relatively open fabric with which the fibers of one surface of the first layer are interspersed and a layer of intermixed fiber and particles of solvent coalescible stiffening agent adhered to the fabric surface by an adhesive which is penetrable by, but not soluble in, the organic solvents used for coalescing the stiffening agent particles. Thus, the fabric layer is secured to both layers of intermixed fiber and coalescible particles in a manner which is not affected by the application of activating solvent in the use of the laminate for the stiffening of shoes. The fabric is capable of limited stretching and serves to prevent disruption of the fiber and particle layers in a manner to distribute stress on the layers and to prevent undue thinning out of the layers under lasting stresses at sharp angles of the last.

Another object of the invention is the provision of an economical flocircd sheet material of superior quality. A dry sheet of felted fibers and particles of stiffening agent rapidly becomes pitted in manipulation, due usually to the rubbing off of particles of the stiffening agent. If this pitted surface is flocked, the flocked surface are hibits irregularities and its appearance is marred. The fabric facing on the composite sheet provided by the present invention, on the other hand, provides a uniform and strong base for flocking, and by flocking the fabric side of such a sheet, an economical flocked sheet material of enhanced appearance is provided adapted for lining and stiffening the heel portions of shoes.

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

FIG. 1 is a partial section, greatly enlarged, of a sheet of stiffener material constituting one embodiment of the present invention;

FIG. 2 is an exploded view of a portion of a sheet of the type shown in FIG. 1;

FIG. 3 is an exploded view illustrating a modification of the invention;

FIG. 4 is an angular view, partly in section, illustrating a stage in the manufacture of one form of the sheet material of the present invention;

FIG. 5 illustrates another step in the preparation of one form of the sheet material of the present invention;

FIG. 6 is a partial section, greatly enlarged, of a sheet material provided by the present invention with adhesive and flock added;

FIG. 7 is a partial section, greatly enlarged, of a laminate of two felted layers of intermixed fibers and plastic particles constituting another embodiment of the present invention;

FIG. 8 is a diagrammatic elevational view, with parts broken away, of a modified screen cylinder type papermaking machine illustrating a stage in the manufacture of a sheet material according to the present invention;

FIG. 9 is a partial cross sectional elcvational view of a modified screen cylinder type papermaking machine illustrating a further stage in the manufacture of sheet material according to the present invention;

FIG. 10 is a partial cross sectional elevational view of a modified screen cylinder type papermaking machine illustrating a subsequent stage in the manufacture of sheet material according to the present invention; and

FIG. 11 is a top plan view with parts broken away illustrating a mixing and propo-rtioning device forming part of the papcrmaking machine used in the manufacture of sheet material according to the present invention.

Referring to FIGS. 1 to 4, the sheet material of the present invention comprises a layer 10 of fibers in which are incorporated coalescible particles of a plastic such as an organic solvent soluble stiffening agent, the layer being sheeted out by filtration from a suitable furnish on a sheet 12 of relatively open, and as illustrated, non-woven, fibrous fabric so that fibers of the layer It) and the sheet 12 are interspersed at the interface 14 (FIG. 4).

The fiber content of the layer 10 may comprise any suitable papermaking fibers or mixture of fibers such as cotton, nylon, jute, hemp, hair, wool, kraft or sulfite pulp, or asbestos. I have found that kraft paper pulp fibers have adequate strength and form a very satisfactory product.

The plastic material for a sheet material intended for shoe stiffening suitably comprises particles of a normally solid, resilient, high molecular weight material soluble at room temperature in a volatile organic solvent and may include, for example, suitable polymers and copolymers of ethylenically unsaturated monomers such as polystyrene or polyvinyl acetate resin, cellulose derivatives such as cellulose acetate, soluble resilient natural resin such as modified rosin, and the like. For uses other than shoe stiffening, the foregoing or other coalescible plastics insoluble in the furnish may be used depending on the properties desired. Thus strong, hard, heatand solventresistant sheets may include particles of uncured thermosctting resins such as phenol aldehyde resins, urea aldehyde resins, melamine aldehyde resins, epoxy resins and the like which may be coalesced by heat or solvent and, usually, pressure.

The furnish is an aqueous dispersion and ordinarily the plastic particle will be selected from, largely or cntirely, water-insoluble materials. However, it is also possible to introduce additives to the furnish which reduce the solubility of desirable plastics possessing some solubility in water. For example, salts, suitably common salt (NaCl), dissolved in the aqueous phase of the furnish are effective to reduce the solubility of uncured aldehyde resins so that they are largely insoluble in the aqueous phase. Acidic materials such as alum and acetic acid may also be used for this purpose.

The particles of plastic may be produced by pulverizing scrap plastic material, for example the scrap resulting from the manufacture of polystyrene lenses which is now commonly available. Many such materials including polystyrene may also be employed in the form of small beads made by known suspension polymerization techniques.

It has been found that the presence of the plastic particles materially increases the ease of draining of the furnish over identical furnishes not containing the plastic particles. Also, the size and shape of the plastic particles has an effect both on the ease of the draining of the furnish, on the ability of the dried material to accept solvent and on the softening effect of the solvent.

Thus, polystyrene particles produced by pulverizing scrap polystyrene lens material in a rotary pulverizer have typically a particle size distribution extending from the size of the pulverizer screen openings down to fine powder. Such pulverized material, mixed with water and fiber in a furnish and strained on a screen, usually produces a sheet somewhat more dense, with slower filtration and slower uptake of activating solvent than a sheet made with plastic in the form of fairly uniform beads of equivalent size. These differences are accentuated where the larger particles are screened out of the pulverized material. On the other hand, small pulverized particles or beads in a sheet tend to soften more rapidly upon application of solvent than larger particles or beads because of the greater surface to volume ratio. It has been found that in order to obtain effective draining of liquid from the fiber and particle layer deposited on a screen to enable rapid and economical manufacturing and at the same time to form a sheet which is readily and completely activatable by solvent within the time available in shoe manufacturing processes, it is important that the particle size distribution be as follows: at least 98% passing a No. 40 sieve, at least passing a No. 100 sieve, and not over 15% passing a No. 200 siever, the percentages being by weight of the original mass of particles and the sieves being of the Standard Screen Series, US. Bureau of Standards, 1919.

The proportion of plastic particles to fiber may be varied considerably, but for most purposes I find that a ratio of about 1 to 5 parts by weight of plastic particles to one part of fiber is most suitable.

in making a sheet according to one form of the present invention, the plastic particles and fiber are beaten up with a suitable quantity of water to form an aqueous dispersion or furnish. The furnish is strained through a sheet 12 of relatively open fibrous fabric disposed on a support 16 to form a composite sheet. The wire screen usually employed as the papermaking filter may be employed as the support. However, the function of the screen being now merely to support the fibrous fabric sheet 12, it may conveniently have a larger mesh. In fact, the support for the facing sheet may be in any form which provides suitable support while permitting filtration through the fibrous fabric sheet.

The fibrous fabric sheet should be thin, relatively open and flexible yet strong. The open character of the sheet is important in relation to its filtering function in permitting drainage of the water of the furnish while holding back the fiber and plastic particles. This character is also involved in providing adequate attachment of the sheet and the layer of fibers deposited thereon since an open sheet permits, during such filtration, interspersion of fibers of the sheet and of the water-laid fibrous layer so that when dry the interspersion of the fibers forms a means of attachment between the sheet and the layer deposited thereon. The sheet may be made from hemp (e.g. rope paper) or other fibers. If any hon-ding agent is used, it should be insoluble in water so that the fibers will not disintegrate. Although a woven fabric may be employed, I have found particularly suitable a commercial material comprising a sheet of relatively open non-woven rayon fiber fabric. This fabric comes in a number of weights and thicknesses ranging from about 8 to about 30 grams per square yard and from about 3 to about 8 mils in thickness. I have found suitable fabric which is about 8 grams per square yard in weight and about 3 /2 mils in thickness. As an indication of the relative openness of this fabric, a test showed that 4 cubic foot of air at a pressure of 28" of water passed in one minute through a 3.14 square inch area of 10 thicknesses of the fabric.

After sheeting out the furnish to the desired thickness, the composite sheet is dried. The sheet may be as thin as 0.03" but is preferably from about 0.04 to about .055" thick for use in womens shoes and somewhat heavier for mens shoes. After drying, the sheet is rolled under heavy pressure to smooth and compact it after which it will be about of its original thickness.

In one form of the invention, an improved flocked shoe lining material is provided by flocking the compressed sheet on the fabric side as indicated in FIG. 6. Thus the improved lining material provided by the present invention comprises the fibrous layer and fabric sheet 12 with a layer of flock 26 bonded to the sheet 12 by means of a flocking adhesive 28. The usual flocking techniques maybe employed for this purpose. The flocked material is then suitable for dieing out into quarter lining blanks.

Laminated sheet material constituting another form of the present invention (see FIG. 7) includes a felted layer 40 of intermixed fibers and plastic or resinous particles formed on an open woven or non-woven reinforcing fabric 42, suitably a relatively inexpensive woven fabric such as the material known as tobacco cloth, the fibers of the felted fibrous layer 40 penetrating the fabric 42 to form a. mechanical union holding the felted layer 40 and the fabric 42 together. A second felted layer 44 of intermixed fiber and plasticizer resinous particles is secured to the fabric 42 by a layer 46 of an adhesive which is not attached by solvent to which the laminate may be exposed, the laminate being flexible and resistant to delamination when flexed.

Apparatus useful both for supporting the fabric sheet 42 for straining the furnish to form a felted fibrous sheet 40, and also useful for forming a felted fibrous sheet 44 without the use of open fibrous fabric sheet 42 comprises a modified cylinder type paperrnaking machine 48 diagrammatically illustrated in FIG. 8. As there shown, the machine 48 comprises a vat 50 with a flow box 52 at one end for insuring a smooth supply of furnish to the interior of the vat 50. The flow box 52 is of conventional type comprising a bottom wall 54 and an end wall 56 of which the upper edge 58 is adjustable heightwise to regulate flow of furnish from the interior of the flow box 52 to the interior of the vat 50. The bottom wall 54 and end wall 56 extend across the interior of the vat 5t) and cooperate with the side walls 60 and end wall 62 of the vat 50 to define a chamber 64 into which furnish is fed through the pipe 66. A cylinder 68 is rotatably mounted in the vat 50 and is provided with means for driving it (not shown). A pipe 70 for withdrawing liquid is disposed in the interior of the cylinder 68. The cylinder 68 differs from conventional papermaking cylinders in that the wire screen 72 on its surface is of substantially larger mesh. Particularly for the subsequent operation of forming a felted fibrous sheet not employing a fabric it is important that the openings in the screen be at least about /6 greater than the dimension of the largest plastic or resin particles of the furnish to prevent plugging of the screen by the particles. it should be noted that the screen openings may in some instances be somewhat reduced by reinforcing wires and the screen opening size referred to is the actual screen opening. Depending on the size of the plastic particles, there may be used screens from size No. 12 to size No. 30 (US. Bureau of Standards, Standard Screen Series, l9l9).

For the first operation to form a mechanically linked fabric and felted fiber-plastic particle sheet, fabric 42 is withdrawn from a roll 74, passed around a roller 76 which lays it down on the screen 72 of the cylinder 68 and the fabric 42 is carried around the cylinder 68 by rotation of the cylinder. As shown in FIG. 8, the Water component of the furnish passes through the fabric 42 to the interior of the cylinder 68 leaving behind a layer 40 of intermixed fibers and plastic particles. Fibers from the furnish deposited on the fabric 42 penetrate and become entangled with the fibers of the fabric 42 to attach mechanically the deposited intermixture of fibers and plastic particles to the fabric 42. When the fabric 42 and the attached felted layer 40 of fibers and plastic particles have passed 6 nearly around thc cylinder 68, they are lifted from the surface of the cylinder by a couch roll 78 and felt 80 and carried up with the felt over the

rollers

82 and 84 to drying apparatus (not shown).

When a desired amount of the composite fabric 42 and felted fiber layer 40 has been made, the fabric 42 is out While continuing rotation of the cylinder 68. Surprisingly, even after the fabric 42 and portions of the layer 40 formed on the fabric 42 have been completely withdrawn from the machine, the cylinder 68 continues to form a satisfactory felted sheet 44 of intermixed fibers and plastic particles. It appears that where the major portion of the screen 72 of the cylinder 68 is covered with a fibrous layer either by the last portions of the fabric 42 (see FIG. 9) or by the felted fiber and particle sheet 44 (see FIG. 10) the rate of flow of dispersion through the uncovered portions of the screen 72 entering the body of furnish in the vat 50 and the relatively low hydrostatic pressure adjacent the line of entry of the screen into the furnish allows the fibers and particles to build onto the existing

fibrous layer

40 or 44 on the screen and continue to form a layer 44 of intermixed fibers and plastic particles even through the openings in the screen are so large as to cause substantial difficulty in initiating and carrying out sheet formation by usual papermaking practices. When the fabric sheet 42 is no longer supplied, a substantially higher volume of liquid passes through the screen 72 and this liquid contains substantial proportions of fibers and plastic particles. The fiber and plastic material passing to the interior of the cylinder 68 is withdrawn through the discharge pipe 70 and passed to a mixing and proportion ing device 86 {see FIGS. 8 and ll) for admixture with additional concentrated furnish to form a furnish having a concentration suitable for supply to the vat 50 of the machine 48. This mixing and proportioning device 86 comprises a cylindrical vat 88 divided by

partitions

90, 92 and 94 into three compartments. The liquid withdrawn from the cylinder is discharged into the compartment defined by

partitions

92 and 94 and concentrated furnish is supplied to the compartment defined by partitions and 94. Overflow pipes 96 and 93 are provided to insure that the level of liquid in these two compartments does not rise above a predetermined height. Adjustable valve controlled

openings

100 and 102 are provided in the lower portions of the

partitions

90 and 92 respectively so that withdrawn liquid and fresh concentrated furnish flow at controllable rates from their respective compartments into a third compartment defined by

partitions

90 and 92 where they mix and are withdrawn through pipe 66 and pumped back to the flow box 52 of the vat 5G for use in making further felted fibrous sheet.

The felted fibrous sheet 44 without fabric is lifted from the surface of the cylinder 68 by the couch roll 78 and felt 8i! and carried along by the felt 8!) over the

rollers

82 and 84 and is dried by suitable drying means (not shown).

The surface of the woven fabric 42 of the composite sheet is coated with a high viscosity, low solids content adhesive layer 46 which when dried will not be affected by organic solvent material. A suitable and inexpensive adhesive is a borax treated aqueous solution of dextrin which is known per se. The viscosity of the adhesive must be kept high, e.g. in the range of 75,000 to 125,000 cps, to avoid penetration of the adhesive into the fibrous sheet. Penetration of the adhesive would mask the plastic granules and prevent their being softened by activating solvent. Also, high viscosity adhesive remains on the surface of the sheet where it is effective to establish a bond. After application of the layer 46 of this adhesive the felted sheet 44 of intermixed fibers and resin particles not having a woven fabric sheet is pressed down on the adhesive layer 46 and the adhesive allowed to dry to a solvent-insoluble but solvent permeable condition.

The following examples are given for purposes of illustration rather than limitation; all parts are by weight:

Example 1 Kraft paper 7V2 Polystyrene lens scrap 25 The polystyrene material was pulverized in a rotary pulveriz/er having a .027" screen. The kraft paper was beaten with about 700 g. of water until pulped and the pulverized polystyrene was then mixed in thoroughly. The resulting furnish was strained through an 8 x 8" sheet of relatively open non-woven, rayon material weighing *8 grams per square yard and 3 /2 mils thick, the sheet being supported on a wire screen of approximately 40 mesh. The sheet was dried and then rolled from about .075" to about .050" thickness. The resulting sheet was firm, brown and fairly uniform except that a few of the larger particles tended to crumble ofi the unprotected face. It wet out readily with MEK and dried in resilient coalesced condition.

Example 2 This example was made in the same way as Example 1 except that the pulverized polystyrene was screened through a 35 mesh sieve. This screening removed the larger particles which had tended to crumble off theunprotected face so that there was considerabl less dlSlIltegration of resin particles during a given amount of handling. The sheet was a little firmer after rolling than in Example 1, drained a little more slowly and absorbed MEK a little more slowly.

Example 3 The same proportions and materials were used as in Example 1 except that the pulverized polystyrene had been screened through a 60 mesh sieve. The differences noted in Example 2 were accentuated. A fairly slow drain and quite firm sheet resulted after rolling. The dried sheet absorbed MEK less rapidly than in Example 2 and dried in a firm resilient condition.

Example 4 Kraft paper 7 /2 Polystyrene beads 25 In this example the polystyrene was provided in the form of beads made by emulsion polymerization, the beads being of fairly uniform size approximately 1 mm. in diameter. A sheet was made by the steps described in Example 1 and after rolling it was found to be very uniform. The drainage and solvent absorption were relatively rapid, somewhat more so than in Example 1. It appeared, however, to take somewhat longer to soften the polystyrene than in the other examples.

Example A sheet of material was made as in Example 2 and a conventional rubber base curing type adhesive (Cement #147, B. B. Chemical Co., Cambridge, Mass), was aplpied to the fabric side of the sheet followed by the application of /2 mm. rayon flock while heating with a rotating hexagonal beater bar on the other side. The sheet was then placed in an oven at 270 F. for minutes to cure the adhesive. The resulting flocked surface Was smooth and uniform. A shoe heel lining element was cut from the sheet in the shape of a counter pocket having a generally rounded upper edge and a straight lower edge with a V-notch at the center. The element was stitched to the heel portion of a shoe upper at its top and sides and after assembly was solvent activated by applying methyl ethyl ketone by brush to its inner surface. The lining element was then pressed against the upper, simultaneously clos- 8 ing the V-notch, slightly overlapping the edges thereof. The shoe was then pulled over and lasted. When the last was pulled, the lining of the shoe was found to present a smooth, pleasing, unwrinkled appearance and heel portions adjacent to the activated stiffener element were found to be resiliently supported thereby.

Example 6 A furnish was prepared by beating kraft pulp in water using a Hollander type beater device. The furnish was adjusted to a fiber content of 0.14% fiber and there was then introduced polystyrene beads of which 100% pass through a No. 16 screen (screen opening 0.047), 99.7% pass through a No. 40 screen (screen opening 0.0165"), pass through a No. screen (screen opening 0.0006"), and 5% pass through a No. 200 screen (screen opening .003") in amount to bring the resin content of the furnish to 0.35%.

Tobacco cloth was drawn from a. roll and laid down on the screen of a cylinder type papcrmaking machine by a roll resting on the screen at the top of the cylinder. The screen was No. 14 (screen opening 0.0555). The cloth was brought around the cylinder and around a couch roll and felt at the top of the cylinder.

The cylinder which was 18" in diameter was set in rotation at about 3 r.p.rn. and furnish introduced into the flow box of the machine to fill the vat of the machine nearly to within 2" of the top of the cylinder. The white water from the furnish strained through the cloth on the cylinder screen leaving behind a layer of intermixed fiber and resin. The liquid entering the interior of the cylinder was withdrawn and passed to a mixing device where it was combined with further furnish to bring its fiber content to 0.14% and returned to the flow box. The layer of intermixed fiber and resin particles increased in thickness as it passed around the cylinder and was lifted off the screen by the couch roll and felt. The fibers of the intermixed fiber and resin particle layer penetrated the fibers of the tobacco cloth to an extent sufiicient to hold the fiber and resin particle layer firmly to the tobacco cloth. The composite was sent to a drier and dried.

While the cylinder continued to turn, the tobacco cloth was cut intermediate the supply roll and the laying down roll and was drawn around the cylinder and carried off by the couch roll and felt. A layer of intermixed fiber and resin particles formed directly on the screen even after the last of the tobacco cloth had passed around the cylinder and this layer was picked off the cylinder screen by the couch roll and felt as a firm intermixed fiber and resin particle layer. It was found that when the tobacco cloth was no longer supplied, there was an increase in the amount of liquid entering the interior of the cylinder and also a higher proportion of fiber and resin so that the mixing and proportioning device was adjusted to change the ratio of fresh furnish blended with the liquid withdrawn from the interior of the cylinder.

The dried composite sheet of tobacco cloth and intermixed fiber and resin particle was coated on the cloth side with an aqueous adhesive having a viscosity of 109,000 cps. comprising 300 parts by weight dextrin, 300 parts by weight of water, 30 parts by weight of borax, and 9.5 parts by weight of a 25% by weight aqueous solution of NaOH. Directly thereafter the dried sheet of intermixed fibers and resin particles without the tobacco cloth was pressed against the adhesive coating and the water content of the adhesive allowed to dissipate to set up the adhesive to bind the products firmly together.

After the adhesive had dried and hardened, the laminate was treated with a solution comprising 8 parts of methyl ethyl ketone and 16 parts of toluol. The activating solution rapidly and completely penetrated and softened the laminate. The solvent was allowed to evaporate and the dried laminate dried in stifi'ly resilient condition in which the resin particles were coalesced.

9 Example 7 Thermosetting phenol formaldehyde resin was ground and passed through a No. 200 screen to remove coarse particles. l g. samples were added to beakers containing 200 cc. respectively of plain water, a by weight solution of alum, a 1% by weight solution of acetic acid and a 5% by weight solution of sodium chloride. These samples were allowed to stand overnight, were centrifuged for 90 minutes at 2,000 rpm. and the liquid poured off. The solids separated by centrifuging were dried overnight at 95 C. in a vacuum oven and were then weighed. It was found that the resin in plain water had lost nearly of its weight; that in the alum solution had lost about 7%; that in the acetic acid had lost about 6 /2 while the resin in the salt solution had lost only 0.6%.

A 5% salt solution was supplied to a Hollander type beater device as the liquid component and ltraft pulp was introduced to the heater and dispersed therein to form a furnish having a fiber content of 0.14%. There was then introduced and beaten in powdered thermosetting phenol formaldehyde resin to the extent of five times the weight of the fiber in the furnish.

Relatively open non woven rayon fiber material weigh ing 8 g. per square yard and 3% mils thick was drawn from a roll and laid down on the screen of the cylinder type papermalting machine employed in Example 6 by a roll resting on the screen at the top of the cylinder. The screen was No. i4. The fiber sheet was brought around the cylinder and around a couch roll and felt at the top of the cylinder.

The papermakin g machine was operated using the pro cedure set forth in Example 6 to form during initiai stages a composite sheet comprising the non-woven fabric and a felted fiber and resin particle layer. When the machine was operating smoothly, the supply of non-woven fibrous sheet was cut off and the machine operated to form a firm intermixed fiber and resin particle layer. The resulting unsupported layer of intermixed fibers and resin particles was dried at a temperature not over 140 F. and lightly pressed after drying. The sheet material was reduced to strong, hard, heat and solvent resistant condition by disposing the sheet between platens at a pressure of 200 lbs. per square inch, raising the temperature of the platens to 295 F. and then cooling.

Example 8 An aqueous solution containing 5% by weight of alum was supplied to a Hollander type beater as the liquid component of a furnish and kraft pulp was introduced to the heater and dispersed therein to form a furnish having a fiber content of 0.14%. There was then introduced and beaten in powdered thermosetting phenol formaldehyde resin to the extent of five times the weight of the fiber in the furnish. The furnish was supplied to a cylinder type papermaking machine following the procedure set forth in Example 7 and the machine operated to produce a firm intermixed fiber and resin particle layer which was dried and pressed. The sheet material thus obtained was reduced to strong, hard, heat and solvent resistant condition by disposing the sheet between platens at a pressure of 200 lbs. per square inch, raising the temperature of the platens to 295 F. and then cooling.

Example 9 An aqueous solution containing 1% by Weight of acetic acid was supplied to a Hollander type beater as the liquid component of a furnish and krait pulp was introduced to the heater and dispersed therein to form a fur nish having a fiber content of 0.14%. There was then introduced and beaten in powdered thermosetting phenol formaldehyde resin to the extent of five times the weight of the fiber in the furnish. The furnish was supplied to a cylinder type papermaking machine following the procedure set forth in Example 7 and the machine operated 10 to produce a firm intermixed fiber and resin particle layer which was dried and pressed. The sheet material thus obtained was reduced to strong, hard, heat and solvent resistant condition by disposing the sheet between platens at a pressure of 200 lbs. per square inch, raising the temperature of the platens to 295 F. and then cooling.

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

l. Solvent activatable stiffener material for stiffening end portions of shoes comprising a layer of water-laid felted fibers containing particles of a normally solid co alescible stiffening agent soluble at room temperature in a volatile organic solvent, a sheet of relatively open fibrous fabric on one face of said layer, fibers of said layer and fibers of said fabric being interspersed at the interface and providing a mechanical link between said layer and said sheet, said particles being present in the ratio of from about I to about 5 parts by weight of particles to 1 part by weight of fibers, and said particles being of a size distribution as determined with U.S. Standard Sieves in which at least 98% will pass through a No. 40 sieve, at least about will pass through a No. sieve, and not more than 15% will pass a No. 200 sieve.

2. Laminated solvent activatable stiffener material for stiffening end portions of shoes comprising a layer of water-laid felted fibers containing particles of a normally solid coalescible stiffening agent soluble at room temperature in a volatile organic solvent, a sheet of reinforcing fibrous fahric on one face of said layer, fibers of said layer penetrating and being interspersed with fibers of said fabric and providing a mechanical link between said layer and said sheet, a second layer of waterlaid felted fibers containing particles of a normally solid coalescibie stiffening agent soluble at room temperature in a volatile organic solvent and a layer of adhesive penetrable by but insoluble in said volatile organic solvent bonding a surface of said second layer to the surface of said sheet.

3. Laminated solvent activatable stiffener material for stiffening end portions of shoes comprising a layer of water-laid felted fibers containing particles of a normally solid coalescible stifi enin g agent soluble at room temperature in a volatile organic solvent, a sheet of reinforcing fibrous fabric on one face of said layer, fibers of said layer and being interspersed with fibers of said fabric penetrating and providing a mechanical link between said layer and said sheet, a second layer of water-laid felted fibers containing particles of a normally solid coalescible stiffening agent soluble at room temperature in a volatile organic solvent and a layer of adhesive penetrable by but insoluble in said volatile organic solvent bonding said second layer to the surface of said sheet, said particles of stiffening agent being present in the ratio of from about I to about 5 parts by weight of particles to 1 part by weight of fiber in each of said layers of felted fibers.

4. Laminated solvent activatab le stiffener material for stiffening end portions of shoes comprising a layer of water-laid felted fibers containing particles of a normally solid coalescible stiffening agent soluble at room temperature in a volatile organic solvent, a sheet of reinforcing fibrous fabric on one face of said layer, fibers of said layer penetrating and being interspersed with fibers of said fabric and providing a mechanical link between said layer and said sheet. a second layer of water-laid felted fibers containing particles of a normally solid ooalescible stiffening agent soluble at room tempenature in a volatile organic solvent and a layer of adhesive penetrable by but insoluble in said volatile organic solvent bonding said second layer to the surface of said sheet, said particles of stiffening agent being of a size distribution as determined with U.S. Standard Sieves in which at least 98% will pass through a No. 40 sieve, at least about 80% will pass through a No. 100 sieve and not more than 15% will 1 1 pass a N0. 200 sieve, said particles being present in each of said layers in the ratio by weight of from about 1 to about 5 parts to 1 part of fiber.

5. Solvent activatable stifiener material for stiffening end portions of shoes comprising a relatively open reinforcing fibrous fabric and a Water-laid felted fiber layer containing intermixed discrete particles of a normally solid eoalescible stiffening agent soluble at room temperature in a volatile organic solvent, with fibers of said layer penetrating and entangled with fibers of said fabric in the interface between said fiber layer and said fabric and constituting a mechanical union between said fiber layer and said fabric holding said layer to said fabric, said particles of stiffening agent comprising not more than 12 15% of fine powder and said particles being present in said layer in the ratio of from about 1 to about 5 parts by weight of particles to 1 part by weight of fiber in said layer.

References Cited in the file of this patent UNITED STATES PATENTS 1,703,961 Schmidt Mar. 5, 1929 l,731,754 Richards Oct. 15, 1929 1,861,044 Ballard May 31, 1932 2,077,125 Miller Apr. 13, 1.937 2,616,821 Harrison Nov. 4, 1952 2,704,965 Seybold Mar. 29, 1955

Claims

1. SOLVENT ACTIVATABLE STIFFENER MATERIAL FOR STIFFENING END PORTIONS OF SHOES COMPRISING A LAYER OF WATER-LAID FELTED FIBERS CONTAINING PARTICLES OF A NORMALLY SOLID COALESCIBLE STIFFENING AGENT SOLUBLE AT ROOM TEMPERATURE IN A VOLATILE ORGANIC SOLVENT, A SHEET OR RELATIVELY OPEN FIBROUS FABRIC ON ONE FACE OF SAID LAYER, FIBERS OF SAID LAYER AND FIBERS OF SAID FABRIC BEING INTERSPERSED AT THE INTERFACE AND PROVIDING A MECHANICAL LINK BETWEEN SAID LAYER AND SAID SHEET, SAID PARTICLES BEING PRESENT IN THE RATIO OF FROM ABOUT 1 TO ABOUT 5 PARTS BY WEIGHT OF PARTICLES TO 1 PART BY WEIGHT OF FIBERS, AND SAID PARTICLES BEING OF A SIZE DISTRIBUTION AS DETERMINED WITH U.S. STANDARD SIEVES IN WHICH AT LEAST 98% WILL PASS THROUGH A NO. 40 SIEVE, AT LEAST ABOUT 80% WILL PASS THROUGH A NO. 100 SIEVE, AND NOT MORE THAN 15% WILL PASS A NO. 200 SIEVE.