US3476626A - Method of making a needled composite sheet - Google Patents

Description

N 1969 R. E; CHARLTON, JR., ETAL 3,476,626

METHOD OF MAKING A NEEDLED COMPOSITE SHEET Original Filed Jan. 12, 1962 BY Pu s? 7/5, WWI/W54.

Azm/Q FM United States Patent 3,476,626 METHOD OF MAKING A NEEDLED COMPOSITE SHEET Richard E. Charlton, Jr., and Rupert A. McDaniel, Fairfax, Ala., assignors to West Point-Pepperell, Inc., a corporation of Georgia Continuation of application Ser. No. 165,829, Jan. 12, 1962. This application May 29, 1968, Ser. No. 733,747 Int. Cl. 1332]) 31/20 US. Cl. 156-148 2 Claims ABSTRACT OF THE DISCLOSURE A method of forming composite products such as auto headliners is disclosed, which comprises the steps of contacting a rigid thermoplastic sheet with a non-woven fibrous web. heating and softening the sheet, and needle punching the web into said softened sheet, said heating and softening being continued until the needle punching is completed. The composite product is readily moldable with heat and pressure, and suitable for formation into auto headliners, side panels and the like.

Reference to related application The present application is a continuation of copending United States application Ser. No. 165,829, filed Jan. 12, 1962, now abandoned.

A principal object of the invention is to provide plastic panels having textile simulating surfaces. A further object is to provide moldable panels of novel decorative nature; the invention encompasses a wide range of decorative and utilitarian variations. A related object is to provide a simple needle punch method for attachment of non-woven fibrous webs to rigid thermoplastic sheets, the method being readily controllable to produce uniform product in substantially continuous manner. Still another object is to provide novel apparatus for producing the composite product of the invention, utilizing as a major element thereof conventional needle loom equipment. Further objects will be in part evident and in part pointed out hereinafter.

The invention will be clearly understood from the following description and the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view illustrating an exemplary apparatus and procedure in accordance with the invention, and

FIGURE 2 is a sectional view, on enlarged scale, of the resultant composite product.

Referring to the drawing, FIGURE 1 illustrates a conventional needle loom indicated generally as 10, including the usual needle board 12, needles 14, stripper plate 16 and bed plate 18. 20 represents an extended guide plate mounted adjacent the loom bed plate 18, and leading thereto, that is on the infeed side thereof. As shown, the upper surfaces of the bed plate 18 and guide plate 20 are substantially coplanar.

Below the bed plate 18 is mounted an electrical resistance heating coil 22, controlled by a thermostat 24, and a separate electrical resistance heating coil 26 is mounted below the guide plate 20, and controlled by thermostat 28. The resistance coils are mounted close to the associated plates, and desirably adjoin the entire plate area, the coil layout being adapted to evenly heat the plates.

Adjacent the outer end of the guide plate 20 is shown a stack 38 of plastic sheets 32. Above the guide plate 20 is mounted a supply roll 34 of non-woven fabric 36. The fabric 36 extends from supply roll 34 to the guide roll 38, mounted just above the guide plate 20, and therebelow as shown in the drawing. On the outfeed side of the needle 3,476,626 Patented Nov. 4, 1969 loom 10 may be provided a coacting pair of drive rolls 40, adapted to engage the product leaving the needle loom 10 and draw the material through the' loom.

The sheets 32, in accordance with the present inventron, may be of any thermoplastic material having a softening point not detrimental to the fibrous web to be applied thereto. Numerous synthetic organic thermoplastic materials may be utilized, including but not limited to polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylonitrile, acrylonitrile butadiene styrene, polypropylene, high density polyethylene and butadiene styrene. The thermoplastic sheets 32, in accordance with the present invention, are of such thickness as to be substantially rigid, relatively stiif and self-supporting, and may range in thickness, for example, from 10 mils or less to 40 mils or more. The plastic sheets while exhibiting substantial rigidity are yet flexible, although not in the sense of film flexibility, in that the sheets may not be bent at sharp angles without breaking or permanent deformation. It follows that the thermoplastic sheet material may be supplied in large diameter roll form, as well as in individual sheets.

The non-woven fabric 36 may be of any desired type or weight. The fibrous web may be composed of natural or synthetic fibers, or mixtures thereof, and may be colored, lustered or otherwise decorated as may be desired. The fibrous web may be lightly bonded, or may be an unbonded web. In the latter case, a card web or a plurality of crosslaid card webs may be utilized and supplied in conventional manner, as on a conveyor belt. The Web may be heavily bonded, if desired, but not to the extent that individual fibers may not be readily displaced therefrom and reoriented. As will be evident, the visual character of the product is determined primarily by the fibrous web; an unbonded web will result in a fuzzy or apparently napped surface, a compact relatively heavily bonded web will result in a felt-like surface, and so forth.

As shown in FIGURE 1, plastic sheets 32 may be fed onto the guide plate 20 one after another, either manually or by conventional automatic feed mechanism. The plast1c sheets slide along the guide plate until they pass under the guide roll 38, at which point the non-woven fabric 36 is brought into contact with the upper surface thereof. If deslred, the guide roll 38 may be positively driven, to advance the non-woven fabric and plastic sheets at desired feed rate. The plastic sheet and non-woven fabric assembly then proceeds over the guide plate 20 to the needle loom 10, and is conveniently drawn therethrough by the positively driven drive rolls 40, although other conventional feed means may be employed as well. If guide rool 38 is driven, its speed will be coordinated with the speed of rolls 40.

The guide plate 20 is heated by coil 26 to a temperature suitable to heat the plastic sheet material to softening temperature by the time the assembly reaches the needle loom. The exact temperature of the guide plate must necessarily be varied in accordance with the character of the thermoplastic material, its thickness, the feed rate thereof and other variables. The proper temperature in any case, however, is readily determined, and may be maintained by means of the thermostat 28'. Heat transmission to the plastic material by surface contact has been found to be particularly efficient and readily controllable. The plastic material and/ or guide plate may be heated otherwise than by an electrical resistance heating coil; for example radiant heaters or open gas flames may be utilized as well. It has been found most efiicient, however, to apply heat to the plastic sheet material through the side opposite that to which the non-woven fabric is applied], because of the insulating eifect of the fibrous web.

The plastic sheets with which the invention is concerned cannot be needled by conventional needle loom equipment under ordinary conditions; due to the thickness of the sheet material, the loom needles would break or the sheet would be destroyed. It has been found, however, that if the sheet material is properly heat softened, the assembly may readily be needled. The plastic material cools quickly, however, and it has been found necessary to maintain controlled temperature thereof through the needling operation. For this purpose, the heating coil 22 is provided below the bed plate of the loom, whereby the bed plate may be heated to appropriate temperature to maintain the desired softened state of the plastic sheet. The temperature of the loom bed plate 18 is controlled by thermostat 24, and it has been found frequently desirable in practice to maintain the guide plate 20 and the bed plate 18 at different temperatures. In normal practice, it is desirable that the temperature of the guide plate exceed the temperature of the bed plate, although under some conditions it is preferable to maintain the bed plate at the higher temperature; in any event, individual temperature control of the guide plate and bed plate facilitates optimum operation.

The needles 14 may be of conventional barb type, and the needle board 12 and the throw of the machine are adjusted so that the leading needle barbs penetrate through the underlying plastic sheet of the assembly. With the plastic material in properly softened condition, the needles penetrate the plastic sheet without difiiculty, and their barbs engage fibers of the fibrous web and carry some of them into and through the plastic sheet. The resultant composite product is illustrated in FIGURE 2, wherein it is indicated that each needle penetration leaves a fiber bundle 42 disposed substantially normal to the product plane, the fiber bundles extending through the non-woven fabric 36 and through the sheet perforations 44, and some distance beyond. It has been found that some of the fibers are pressed by the needles into the walls of the perforations 44, and are firmly locked in place by the plastic material when it cools, whereby the fibrous web is firmly associated with the plastic sheet.

If desired, after completion of the product, a binder solution such as starch or an elastomeric dispersion may be applied to the plastic side of the product, in order to more firmly lock the fibers extending therethrough. The additional binder coating may be applied at any time after the needling operation, in any convenient manner. For example, the binder may be applied by brushing or spraying. In most cases, however, the fibrous web is firmly aflixed to the plastic sheet by the needling operation, and a subsequent bonding step is not necessary.

As previously indicated, the appearance of the fabric side of the composite product is determined primarily by the character of the fibrous web or non-woven fabric utilized. This appearance may be altered slightly by the needling operation, and in such case, of course, the appearance is affected by the extent of needling. The plastic sheet on cooling after the needling operation returns to substantially its original state of stiffness and rigidity. Since the sheet is perforated in the course of needling, however, its flexibility is slightly increased thereby, and excessive needling may weaken the plastic sheet, and in extreme cases detract from its rigidity and formability. Depending somewhat on the size of the needles employed, the needling will usually be within the range of from about 100 to about 1,000 punches per square inch, the median part of this range being normally most desirable. By reason of its rigidity with limited flexibility, the product is well suited for use as snap-in panels, either as produced or after subsequent heat shaping,

The following is a specific example of the invention. Rigid polypropylene sheets, approximately 20 mils thick and weighing 13.5 ounces per square yard, were fed to and across the guide plate 20, and a lightly bonded crosslaid web of nylon fibers weighing approximately 6 ounces per square yard was applied to the upper surface thereof by means of guide roll 38. The polypropylene sheets in passage across the guide plate 20 were heated to approximately 300 F., and the temperature of the bed plate 18 was adjusted to maintain the temperature of the polypropylene material at the same value at the outfeed end of the needle loom. The feed and operation of the needle loom were adjusted to eifect approximately 400 punches per square inch, and the needle throw adjusted to attain /8 inch penetration through the plastic sheet. The resultant composite product was substantially rigid and moldable, although exhibiting some flexibility and snap. The fabric side had the appearance of soft woven goods, the needling operation leaving a pleasing striated appearance. The fabric web was securely attached to the plastic sheet backing, and could be detached therefrom only with difficulty.

We claim:

1. Method of making a composite product comprising the steps of contacting a rigid sheet of organic thermoplastic material with a non-woven fibrous web, heating and softening said sheet, and needle punching said web into said softened sheet to produce about -1000 punches per square inch, said heating and softening the sheet being continued until said needle punching is completed.

2. Method of making a composite product comprising the steps of contacting one surface of a rigid sheet of organic thermoplastic material with a non-woven fibrous web, said rigid sheet having a thickness of about l040 mils, applying heat to the other surface of said sheet and softening said sheet, needle punching said web into said softened sheet to produce between about 1001000 punches per square inch, said heating and softening the sheet being continued until said needle punching is completed and permitting the product to cool.

References Cited UNITED STATES PATENTS 1,371,804 3/1921 Nowell l6l64 2,429,486 10/1947 Reinhardt 161-81 2,639,250 5/1953 Reinhardt l61--66 2,959,509 11/1960 Marshall 156-448 3,010,180 11/1961 Hoffman l6l154 X 3,075,867 1/1963 Cochran 15672 3,205,342 9/1965 Smith et al. 156148 X 3,245,854 4/1966 Et-chison et al. l56-148 FOREIGN PATENTS 610,390 10/1948 Great Britain.

OTHER REFERENCES Fibers, Plastics, and Rubbers, Roff; published 1956 by Butterworths Scientific Publications, London; pp. 360, 361, 362 relied on.

Modern Plastics, vol. 32, No. 5, January 1955, Porous Plastics Film and Sheet, pp. 102 and 103 relied on.

ROBERT F. BURNETT, Primary Examiner RAYMOND O. LINKER, JR., Assistant Examiner U.S. Cl. X.R.

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