US 3594262 A
Description (OCR text may contain errors)
July 20, 1971 MAGIDSQN 3,594,262
SHEET MATERIAL Original Filed May 28, 1963 a, W], I 10 a W INVENTOR. #seazer Mae/030w United States Patent US. Cl. 161-94 1 Claim ABSTRACT OF THE DISCLOSURE A three-dimensional article, such as a brassiere cup, having an elastically stretched fabric held in the desired shape by a grid shaped stiffener injection molded to one side thereof.
This application is a streamlined continuation of SN. 283,800, filed May 28, 1963.
This invention relates generally to the stiffening of a fabric or similar porous form of sheet material, and more particularly to the stiffening of a fabric by laminating it with a thermoplastic resin.
In a number of different applications, a stiffened fabric is very desirable, as, for example, in various articles of clothing, in luggage, furniture, packaging, toys, and in numerous other applications. Heretofore it has been common to stiffen a fabric by adhesively securing it to the stiffener, as by coating a sheet of cardboard or similar material with an adhesive, and then applying a sheet of fabric to the cardboard. While such a method of construction may be satisfactory for certain inexpensive forms of luggage, another and better system is desired for many other uses.
By way of example only, it is customary to provide preformed brassiere cups for ladies swim suits, and these cups must be made of a material that is fleXible but not rigid, light in weight, and comfortable to the wearer. The cup material must also be one that is not affected by water or moisture, since it is to be expected that a swim suit will be subjected to repeated cycles of wetting and drying. Under the circumstances, it is desirable to have a cup made of a fabric that will fit next to the body of the wearer and be comfortable, while the fabric is stifiened by some suitable means that has sufficient flexibility to provide a natural appearance.
Heretofore the best approach to the desired form of construction has been to use a fabric, such as a knit material that has a certain degree of stretch, which is adhesively secured to a stiffer and coarser reinforcing material. Thus, certain knitted fabrics, made of materials such as specially processed nylon, will have a stretch in two directions and this particular material is quite soft and comfortable next to the skin.
In the past, when such a brassiere cup was to be made, it was the practice to use a piece of such knit material, stretch it over a form of the desired shape, and then adhesively secure a stiffening material of relatively coarse weave, such as a material known in the trade as nylon horsehair. After the knit material and its stiffener had been adhesively secured together the cup was then ready for trimming and later incorporation in a swim suit. However, the problems of securing proper adhesion are difficult at best, since the use of adhesives often involves the use of solvents that are disagreeable if not toxic, and the drying conditions for such solvents or adhesives are critical. Furthermore, after the swim suit is completed, crushing of the suit can result in the collapse or inversion of the cup, and when this occurs, a crease in the cup is often formed that seriously detracts from the appearance of the suit.
It would be possible to form a stiffener separate from ice the fabric, by pressing a sheet of plastic over the desired form. However, at least two difficulties present themselves if this method is followed. First, the stretching and flow of the sheet plastic will generally cause lack of uniformity of thickness of the stiffening material, requiring very careful control and design of the forming die. Secondly, and more importantly, it has been found that a sheet plastic loses many of its original characteristics when it is reheated to a temperature that will permit its molding to a desired form. It is not known what causes the change in characteristics of the sheet material, but the forming of a reinforcing member by the heating and stretching of a sheet plastic is definitely less satisfactory, and the product has less resilience than the product made by the method herein described.
Another advantage of the present invention is that it enables more intricate forms to be made. Further, with the stretch-shaped reinforcing member, the problem of adhesively securing the fabric to the reinforcing member remains as difficult as ever.
The present invention has been developed to overcome the difficulties heretofore mentioned, and in so doing has provided a material having uses not heretofore considered.
It is therefore a major object of the invention to provide a new sheet material.
Another object of the invention is to provide such a sheet material having many of the characteristics of fabric, and at the same time having a much greater stiffness than can be achieved by the same sheet fabric alone.
It is a further object of the invention to provide such a sheet material that does not require the adhesive or solvent securing of the fabric to the stiffening material in the manner heretofore done.
Still another object of the invention is to provide a sheet material in which the stiffening effect may be selectively controlled from a condition of great flexibility to substantial rigidity.
It is still a further object of the invention to provide a sheet material in which the reproducibility of the article formed is very great, the cost of the article may be kept quite low, and the weight of the article may be kept light.
These and other objects and advantages of the invention will become apparent from the following description of the general features of the invention, and a preferred form thereof, and from the drawings illustrating the general and preferred form in which;
FIG. 1 is a greatly magnified cross-sectional view of a piece of fabric to which a piece of sheet reinforcing material has been secured;
FIG. 2 is a plan view, to a much smaller scale, taken in the direction of the arrow 2 in FIG. 1 and showing thereinforcing grid or network of stiffening material to which the fabric is secured;
FIG. 3 is a perspective view of the open molds that may be used in the formation of brassiere cups, with a frame carrying the stretchable fabric between the two portions of the mold;
FIG. 4 is a cross-sectional view of what might be considered a portion of FIG. 3, with the two sections of the mold closed, the fabric stretched into shape, and the molds ready for receiving the fluid plastic; and
FIG. 5 is a plan view of one form of brassiere cup, such as might be produced by the equipment shown in FIGS. 3 and 4.
At this point, it should be noted that the material hereinafter referred to as the fabric may be a knitted, netted, or woven material formed of natural or synthetic strands, or, as will hereinafter become apparent, may be a foam material such as a polyurethane foam. Thus, by way of example, in addition to the polyurethane foam,
the following materials have been satisfactorily tested; cotton, wool, linen, silk, nylon, acetate, acrylic, and polyester fibers. All of these materials, including the foam are hereinafter included within the group collectively referred to as fabrics, unless the context particularly indicates that one or more materials are not to be included.
The stiffening material may be any one of a number of suitable plastics, and among those tested and found to act very satisfactorily are nylon, polyethylene, polypropylene, acetate, polystyrene, halogenated hydrocarbons (e.g. Teflon) and acetal resin (e.g. Delrin). The foregoing lists are not intended to be exclusive, but are by way of example to show the wide selection of materials suitable, and the general nature of these materials.
Referring now to the drawings, in its simplest form the present invention contemplates the firm attachment of a porous flexible sheet material such as any of the fabrics heretofore noted, to a stiffener member of the type hereinafter described. For convenience, the sheet material will hereinafter be referred to as a fabric even though the term, as used herein, is intended to include the knitted, netted, and woven materials of various fibers including those heretofore mentioned, non-woven sheets such as may be formed of a random pattern of fibers, e.g., felt, and foam materials.
In FIG. 1 of the drawing, a sheet of fabric, designated generally by the numeral 10, is shown bonded to a plastic stiffener 11. The plastic stiffener 11, which appears to be a solid sheet in FIG. 1, is seen in FIG. 2 to comprise a grid consisting of a plurality of interconnected spaced ribs 12 forming recesses or openings 13 through which the fabric is visible. It will be appreciated that the scale to which FIG. 1 is drawn is greatly enlarged, and the individual threads of the fabric 10, clearly visible in FIG. 1, are indistinguishable in FIG. 2 which is drawn to a much smaller scale. It will be appreciated that the plastic stiffening 11 may thus be primarily a very open network or grid that imparts stiffness to the fabric 10 without greatly increasing the weight of the fabric, without materially impairing its porosity, and without changing the characteristics of the free surface of the fabric, remote from the stiffening member.
It is often important, of course, that the characteristics of the fabric itself be changed as little as possible while still imparting additional stiffness to the fabric. Thus, if the fabric is to be placed next to the body, as a brassiere cup may be, the softness and desirable feel of the fabric should not be replaced by the stiff and relatively unyielding feel of a solid plastic surface. Likewise the porosity of fabric should not be impared, since it is important that the skin have the opportunity to breathe and rid itself of sweat. These desirable characteristics, it will be realized, are retained in the form of construction illustrated in FIGS. 1 and 2.
In its simplest form, where the final shape of the fabric 10 is a flat sheet, the sheet of fabric may be laid upon a flat surface and the plastic stiffener applied to it. In other cases, where the final form of the fabric 10 is one in which there are curves in more than one plane, as, for example, in a brassiere cup, the fabric 10 must be stretched over the convex portions of the mold, and consequently under these conditions a stretchable fabric is desirable. It will be appreciated that most fabrics have a certain amount of give or stretch in one or more directions, but certain fabrics, because of the material from which they are made, and the manner in which they are made, have even greater stretch. An example of such a fabric is found in some of the knitted products formed from a nylon filament that has previously been coiled. Such fabrics are available on the market under a number of different names.
Assuming that the fiat sheet form of stiffened fabric, such as shown in FIG. 2, is to be produced, a sheet of fabric is stretched flat, and the plastic stiffener 11 is, by a suitable die, injection molded into one side of the sheet 10. The dies or molds used in the process, particularly in the case of the flat sheet, can be quite simple, and one die will be essentially plain, to receive the fabric sheet 10, while the other die will be essentially flat with grooves cut into it corresponding to the ribs 12 of the plastic stiffener 11. Sprues are provided at suitable intervals so that the plastic may be forced or injected into the mold to fill all of the grooves, the location of the sprues and their spacing being determined by the particular plastic, the temperature at which it is injected, the shape and size of the die, and other well known factors. After the molding is completed the mold is opened and the composite sheet consisting of the fabric 10 and the plastic stiffener 11 is removed. The sprues, as well as the flash, are trimmed in accordance with good molding practice, and the finished article is ready for use.
Surprisingly, the adhesion between the plastic stiffener and the fabric is very good, sometimes being so great that it is almost impossible to separate the fabric from the plastic stiffener. The plastic stiffener normally dOes not, and should not penetrate through the fabric, since this would change both the feel and the appearance of the fabric. Instead, the plastic stiffener engages and partially surrounds the adjacent surface of the individual fibers or filaments of the fabric 10. In the case of certain of the fibers, there is a surface roughness that may be caused by scales or hair-like portions that increase the adhesion of the plastic stiffener to the individual fibers or filaments.
Because of the lack of any adhesive as such, the problems of securing and properly applying the correct adhesive and providing the correct drying conditions are eliminated. Moreover, by forming a grid, regardless of its shape, the stiffening effect of a solid sheet can be obtained while the advantages of open, porous, fabric may be obtained. Furthermore, the change in characteristics of the plastic that occur upon the reheating and softening of a sheet are completely avoided. If desired, the entire surface of the fabric 10 may be covered by the plastic stiffener 11, thus increasing the bond between the two. The ribs 12 may still be used to provide additional stiffness, and a most versatile construction is thus provided.
Where a product is to be made that has curvature in two or more different planes, the same general procedure is followed, but the dies, instead of being fiat, are appropriately shaped, and the fabric is one having the necessary amount of stretch or elasticity. Thus, as illustrated in FIG. 3, in the manufacture of a brassiere cup, a die is formed in which one member 20 is shaped to provide the desired interior form of the completed cup, while a cooperating die 21 is shaped to provide the complementary surface of the cup. The die member 20 will thus have a convex portion 22 having a smooth surface, while the die member 21 will have a concave portion or recess into which the convex member will fit. Additionally, the recessed portion of the die member 21 will be provided with grooves adapted to form ribs such as the ribs 12 of the flat form shown in FIG. 2. The particular arrangement of the ribs is a matter that will be dictated by the nature and shape of the products, of course.
The die member 21 is provided with or connected to a reservoir 23 or other source of suitable plastic that may be injected under pressure into the recesses that will form the ribs of the plastic reinforcement. A measured charge is injected into the die cavity so that the grooves forming the ribs are completely filled, and flash is reduced to a minimum. After the molding operation is complete, the die members are separated and the formed fabric with its attached plastic reinforcement is removed from the dies and the excess material trimmed off. The general relationship of the die members of FIG. 3 during the molding process is indicated in FIG. 4. Thus, the lower die member 20, having the convex form 22 thereon is shown beneath the die member 21, having the recess or concave portion complementary to the convex portion 22. A fabric sheet 24 is shown stretched over the convex portion 22 and held down by the upper die 21, while a space 25 between the fabric and the lower surface of the upper die member 21 indicates a groove in the upper die member which, when filled with plastic, will form one of the ribs corresponding to the rib 12 of the fiat form shown in FIG. 2.
Under the proper conditions, it is possible to mold a plastic stiffener 11 to each side of a fabric 10. This is a more specialized form of construction and process, and usually requires either that the fabric be in the form of a fiat sheet or be held in the desired shape by appropriate portions of the dies. Such double coated or bonded products have a more restricted application.
It -will be appreciated, of course, that the brassiere cup shown in FIG. 5 is but one of the many forms that can be made by the process of the present invention. Many other articles of clothing, such as girdles, corsets, shirt collars, shoes and other articles may be formed by this process where the appearance or feel of fabric is desired, while the stiffness of a more rigid material is needed. As previously indicated, luggage, packaging, and toys are among the other fields in which this material and the method of making the same will find great usefulness, as well as in the furniture field. In this connection, it should be noted that in many cases a sheet of vinyl material, simulating leather, is applied to a thin layer of foam material such as a polyurethane foam. This laminar form of construction gives the appearance of leather as well as the slight resilience characteristic of true leather. By providing this vinyl-foam combination with a plastic stiffening, the appearance and feel of leather may be augmented by a stiffness and light weight, not heretofore obtainable, thus making the product useful for furniture, luggage, and many other uses.
In other forms of construction, where the weave of a fabric contributes an important part of the appearance, it is possible to use a stretch fabric with the present construction and eliminate the seams that have heretofore been necessary with adhesive type stiifeners.
From the foregoing, it will be seen that there has been provided a product and a method of making the same fully capable of achieving the objects and securing the advantages heretofore set forth. While a preferred form of the invention has been disclosed, it will be appreciated that the invention is not to be limited to the particular form arrangement of parts, or sequence of operations herein described and shown, except as limited by the following claim.
1. A stiffened, non-rigid laminated article which includes: a sheet of elastic fibrous fabric stretched into and held in a desired three-dimensional shape; and a grid shaped stiffener member of plastic injection molded to one side of said fabric such that said plastic engages and partially surrounds the individual fibers on said one side of said fabric, said stiffening member holding said fabric in stretched condition and being bound to said fabric solely by a bond formed between the plastic and the partially surrounded fibers on said one side of said fabric.
References Cited UNITED STATES PATENTS 2,379,971 7/1945 Krehbiel 264-328UX 2,965,932 12/1960 Knowles 264328X 3,026,573 3/1962 Ciaio 264244X 3,122,598 2/1964 Berger 264328X 3,320,346 5/1967 Galitzki et al 264258X 3,035,291 5/1962 Bingham, Jr. 264244X FOREIGN PATENTS 1,271,522 8/1961 France 264244 ROBERT F. WHITE, Primary Examiner T. I. CARVIS, Assistant Examiner US. Cl. X.R.