Loop fastener portion with thermoplastic resin attaching and anchoring layer

Abstract: A loop fastener portion (10) including a soft flexible sheet-like fibrous structure (12) having a multiplicity of loops (14) along a first surface (16) adapted to be releasably engaged by a mating fastener portion, and a layer (18) of thermoplastic resin adhered to a second major surface (20) of the fibrous structure (12) which anchors the loops (14) in the fibrous structure (12) and is softenable by the application of heat to adhere the fastener portion (10) to a substrate such as the surface of a disposable diaper.

Description: Technical Field The present invention relates to fastener portions including loops adapted to be releasably engaged by mating fastener portions which may include hooks or headed stems. Background Art Fastener portions including loops (called loop fastener portions herein) adapted to be releasably engaged by other fastener portions which may include hooks or headed stems are well known in the art. Typically, such a loop fastener portion comprises a soft flexible sheet-like fibrous structure having a multiplicity of loops along a first major surface, which fibrous structure may be formed by any of several methods such as weaving, knitting, warp knitting, weft insertion knitting, stitch-sewing or the known methods for making nonwoven structures. Such loop fastener portions may also include adhesive coatings (e.g., thickened or foamed latex) to help bond together their fibers at their contact points both to restrict the loops on the loop fastener portions from enlarging and to restrict the fastener portions from tearing when tension is applied to the loops by mating fastener portions with which the looped fastener portions are engaged, such as upon the disengagement of such fastener portions. Some such loop fastener portions are intended to be sewn in place, particularly where they are used on articles (e.g., clothing) that will be washed or dry cleaned. Other such loop fastener portions include a layer of pressure sensitive adhesive on their surface opposite their loops, which is often the preferred method of attaching loop fastener portions to objects that do not require launderability or that cannot be sewn. Both of these methods of attachment have certain disadvantages, however. Sewing typically is labor intensive and can decrease the area of the fastener portion that can be engaged by a mating fastener portion. Also to facilitate sewing the fibrous structure of the loop fastener portion should have sufficient internal strength and integrity so that it can be held in place with a reasonable number of stitches, and thus it is impractical to sew certain types of loop fastener portions that may have, for example, nonwoven fibrous structures. When pressure sensitive adhesives are used, the fibrous structures must be sufficiently nonporous to prevent the loops from sticking to the adhesives and thus becoming unavailable for engagement with mating fastener portions. Also, prior to use, pressure sensitive adhesives on such loop fastener portions must be protected as by a liner which must be removed before the loop fastener is attached to an object. FR-A-2,198,712 discloses a female fastener element which consists of a substrate having first and second major surfaces, with a multiplicity of loops perpendicular to one of the major surfaces and a film or layer of plastic covering the second of the major surfaces. The plastic layer is a low melting point thermoplastic adhesive resin, which is softened by the application of heat to attach the female fastener portion, for example to a garment. US-A-3,694,867 discloses a female fastener portion consisting of a high-loft, non-woven fabric having first and second major surfaces, with a multiplicity of loops along a first major surface for releasable engagement by a male fastener portion. During manufacture an intaglio pattern of thermoplastic resin is applied to the second major surface, and the cooperative action of a drum and gathering blade consolidates the open adhesive pattern into a layer of adhesive with random openings therethrough. Before application of the adhesive the fabric web has sufficient internal strength to enable it to be placed under tension. Disclosure of the Invention The present invention provides a loop fastener portion including a fibrous structure and a simple means by which it may be fastened to an object which allows the loop fastener portion to be easily attached, bonds together the filaments of the fibrous structure to anchor the loops, sufficiently anchors the filaments to the backing so that even fibrous structures with relatively low internal strength and integrity can be used and will still provide loops that will provide shear and peel strengths comparable with loops from tightly woven fibrous structures, and does not present the possibility that loops will become adhered to it even when the fibrous structure is relatively porous. According to a first aspect of the present invention there is provided a fastener portion including: a soft flexible sheet-like fibrous structure having first and second major surfaces and a multiplicity of loops along said first surface adapted to be releasably engaged by a mating fastener portion; and a layer of thermoplastic resin adhered to the second major surface of said fibrous structure, said layer of thermoplastic resin anchoring said loops in said fibrous structure and being softenable by the application of heat to afford adhering said fastener portion to a substrate, characterized in that said layer of thermoplastic resin is a continuous layer, said fibrous structure is a lofty non-woven fibrous structure with initial low web integrity or internal strength, and said thermoplastic resin provides the fibrous structure with sufficient internal strength and integrity for use. According to a second aspect of the present invention there is provided a method for forming a loop portion for a hook and loop fastener comprising: providing a soft flexible sheet-like fibrous structure comprising a non-woven layer having first and second major surfaces and a multiplicity of loops along its first surface adapted to be releasably engaged by the hook portion of the fastener, which non-woven layer along has insufficient internal strength to adequately anchor the loops for use as the loop portion of a hook and loop fastener; extruding a layer of thermoplastic resin onto the second major surface of said fibrous structure sufficient to bond together the fibrous structure and to add sufficient internal strength and integrity to the fastener portion and anchoring of the loops to afford use of the loop fastener portion with the hook portion of a hook and loop fastener; and adhering the layer of thermoplastic resin to a substrate. The thermoplastic resin may be of any conventional type such as polyethylene, polypropylene, blends and copolymers thereof, ethylene acrylic acid copolymer, nylon copolymers, or ethylene vinyl acetate copolymers and can be applied in any one of several methods such as by extrusion or roll coating of molten thermoplastic material directly onto the fibrous structure or by adhering thermoplastic film to the fibrous structure by hot nip lamination (i.e., softening only one surface portion of the thermoplastic film, pressing that softened surface against the fibrous structure, and allowing it to cool). After application, the thermoplastic resin will bond together the filaments of the fibrous structure to anchor the loops and will anchor the filaments and add sufficient internal strength and integrity to the loop fastener portion so that even very porous non-woven structures are usable to form the loops. The thermoplastic resin can be simultaneously applied both to the fibrous structure and to a substrate and thus used to adhere the fibrous structure to a substrate, as may be useful in making the coated abrasive structures described and claimed in U.S. Patent No. 4,609,581. Alternatively the thermoplastic resin can first be allowed to solidify and adhere to the fibrous structure and can subsequently be softened along its surface opposite the fibrous structure by exposure to heat, as by contact with a heated surface or from an infrared source of radiation, so that it will adhere quickly and securely to a substrate with which it is brought in contact (i.e., the polymeric outer layer of a disposable diaper) and the thermoplastic resin can add sufficient strength so that the loop fastener portion can be handled and applied to such a substrate at a high speeds by automated equipment even when the fibrous structure by itself would have insufficient internal strength to afford such handling. Brief Description of the Drawing The present invention will be further described with reference to the accompanying drawing wherein like numbers refer to like parts in the several views, and wherein: Figure 1 is an edge view of an embodiment of a loop fastener portion according to the present invention shown attached to a substrate; Figure 2 schematically illustrates a method for forming loop fastener portions according to the present invention; and Figure 3 schematically illustrates application of a loop fastener portion according to the present invention to a substrate. Description of the Preferred Embodiment Referring now to Figure 1 there is shown a loop fastener portion according to the present invention generally designated by the reference numeral 10. The fastener portion 10 includes a soft flexible sheet-like non-woven fibrous structure 12 having a multiplicity of loops 14 along a first surface 16 adapted to be releasably engaged by a mating fastener portion (not shown); and a layer 18 of thermoplastic resin adhered to a second major surface 20 of the fibrous structure. Thermoplastic resin in the layer 18 anchors the loops 14 in the non-woven fibrous structure 12 and is softenable by the application of heat to adhere the fastener portion 10 to a substrate such as the substrate 22 which may be a polymeric outer sheet of a diaper. Referring now to Figure 2 there is schematically illustrated one method for applying a layer 50 of thermoplastic resin to a second surface 51 of a fibrous structure 52 having a plurality of loops along a first surface 53 to provide a laminate 60 that could be cut into pieces to provide fastener portions like those described above. As illustrated, the fibrous structure 52 is pulled from a supply roll 54 around a guide roller 55 around a first chrome plated application roll 56 and through a nip between the first application roll 56 and a second rubber covered application roll 57. A drop die 58 from an extruder 59 deposits molten thermoplastic material along the nip between the second surface 51 of the fibrous structure 52 and the second application roll 57. The layer 50 of thermoplastic material is adhered to the fibrous structure 52 at the nip between the application rollers 56 and 57, and the layer 50 passes with the fibrous structure 52 around a portion of the periphery of the second application roll 57, around a second guide roll 61 and onto a wind up roll 62. Figure 3 schematically illustrates the subsequent application to a substrate 70 of the laminate 60 of the fibrous structure 52 and the layer 50 of thermoplastic material. That laminate 60 is pulled from a supply roll 75 through the nip between spaced application rolls 71 and 72 around a portion of the periphery of the application roll 71 with the layer 50 of thermoplastic material facing outwardly where it will be heated and softened by an infrared heater 73 adjacent the application roll 71. The substrate 70 is pulled from a supply roll 74 and passes through the nip adjacent the softened layer 50 of thermoplastic material where it is pressed into contact with and is adhered to by that layer 50. The resulting composite 80 is then wound on a wind up roller 76. It will be appreciated that the method illustrated in Figure 3 can easily be modified by known means to cut and apply predetermined lengths of the laminate 60 of the fibrous structure 52 and the layer 60 of thermoplastic material to provide loop fastener portions, and can include subsequent steps of separating the substrate into predetermined lengths of a desired shape after those lengths are applied as may, for example, be done in applying such lengths to disposable diapers. The following is an example of a laminate 60 suitable for loop fastener portions that have been made using the method illustrated in Figures 2 and 3. Example 1 A fibrous structure 52 in the form of a carded non-woven web was prepared as follows. Staple fibers (3.175 cm (1¼ inch) cut lengths of 4.75 denier crimped polyester) and binder fibers (3.175 cm (1¼ inch) cut lengths of 8 denier amorphous polyester) were blended at a ratio of 70% to 30% by weight, opened and fed to an even feeder that forms a fiber mat, and then processed in a roller top twin master card which constructed a non-woven web having a basis weight of 101.7 g/m² (3 oz/yd). The web was then thermally set in a hot air oven to provide a lofty non-woven fibrous structure 52 with low web integrity or internal strength. The fibrous structure 52 was then extrusion coated by the method shown in Figure 2 with an ethylene vinyl acetate copolymer resin. The resultant laminated structure 60 could be readily attached to a substrate using the method illustrated in Figure 3.

Claims: A fastener portion (10) including: a soft flexible sheet-like fibrous structure (12) having first and second major surfaces (16, 20) and a multiplicity of loops (14) along said first surface (16) adapted to be releasably engaged by a mating fastener portion; and a layer (18) of thermoplastic resin adhered to the second major surface (20) of said fibrous structure, said layer (18) of thermoplastic resin anchoring said loops (14) in said fibrous structure (12) and being softenable by the application of heat to afford adhering said fastener portion (10) to a substrate (22), characterized in that said layer (18) of thermoplastic resin is a continuous layer, said fibrous structure (12) is a lofty non-woven fibrous structure with initial low web integrity or internal strength, and said thermoplastic resin (18) provides the fibrous structure with sufficient internal strength and integrity for use. A structure according to claim 1 wherein said substrate (22) is the polymeric outer layer of a disposable diaper. A method for forming a loop portion for a hook and loop fastener comprising: providing a soft flexible sheet-like fibrous structure (52) comprising a non-woven layer having first and second major surfaces (53, 51) and a multiplicity of loops (14, 33, 43) along its first surface adapted to be releasably engaged by the hook portion of the fastener, which non-woven layer alone has insufficient internal strength to adequately anchor the loops for use as the loop portion of a hook and loop fastener; extruding a layer (50) of thermoplastic resin onto the second major surface (51) of said fibrous structure sufficient to bond together the fibrous structure and to add sufficient internal strength and integrity to the fastener portion and anchoring of the loops to afford use of the loop fastener portion with the hook portion of a hook and loop fastener; and adhering the layer of thermoplastic resin to a substrate. A method according to claim 3 further including the steps of: allowing the layer of thermoplastic resin to cool after said extruding step and before said adhering step; and said adhering step includes softening the layer of thermoplastic resin by the application of heat and pressing the softened layer of thermoplastic resin (50) against the substrate (70) to adhere the fastener portion to the substrate. A method according to claim 3 wherein said adhering step is performed simultaneously with said extruding step.

Inventors: NESTEGARD SUSAN K C O MINNESOT, OTT RONALD L C O MINNESOTA MIN, NESTEGARD, SUSAN K. C/O MINNESOTA MINING AND, OTT, RONALD L. C/O MINNESOTA MINING AND
Applicants: MINNESOTA MINING & MFG, MINNESOTA MINING AND MANUFACTURING COMPANY
Application year: 1987
Main classification: A44B18
IPC codes: B32B7, B32B5, A44B18