The present invention relates generally to a printed loop fabric with improved graphic visibility and clarity which may be used as the female portion of a mechanical closure system. The loop fabric is generally comprised of a knit fabric. More specifically, the fabric is comprised of a warp knit, weft inserted lap side loop pile fabric having adjacent loops in each wale alternate from one direction to the other. The methods employed to create the printed loop fabric having improved graphic visibility and clarity also provide a printed loop fabric that exhibits sufficient hook to loop engagement strength desired for the fabric's end use as the female portion of a mechanical closure system.
One method of creating the printed loop fabric includes coating the backside of the loop fabric with a thermoplastic material and then printing the face side of the coated fabric. This method generally eliminates the need to rely upon the “see through” characteristics of the fabric, adhesive, or film comprising the product, in order to see the printed image and results in a printed loop fabric with improved graphic visibility and clarity.
Alternatively, the printed loop fabric may be achieved by applying a thermoplastic material to the backside of the loop fabric and printing on the thermoplastic material. This method of obtaining a printed loop fabric relies upon the see through characteristics of the fabric. Accordingly, it may be preferable to use a loop fabric comprised of low loops which provides increased open space between the yarns of fabric. The resulting fabric exhibits improved graphic visibility and clarity of the printed image applied to the backside of the fabric.
The printed loop fabric may also be produced by applying a thermoplastic material to the backside of a loop fabric comprised of low loops and laminating a pre-printed film to the thermoplastic material. Again, due to the increased open space between the yarns of the low loop fabric, the printed low loop fabric having a pre-printed film laminated to the thermoplastic material also exhibits improved graphic visibility and clarity when compared with other similarly constructed fabrics.
The printed loop fabric of the present invention may be utilized as part of the mechanical closure system for disposable diaper products. It has been generally established that consumer market demands a product printed with patterns, characters, or words for the purpose of landing zone identification, which provides a locator for the hook portion of the closure system, and brand recognition. Accordingly, market advantage may be gained in offering a loop product with the best print visibility and clarity. Currently, most loop fabrics created for this purpose are laminated to pre-printed films and have less print clarity and graphic visibility than the printed loop fabric of the present invention. The current invention discloses a printed loop fabric with improved graphic visibility and clarity and sufficient hook to loop engagement strength, which are important attributes for the fabric's end use as the female portion of a mechanical closure system. In at least one embodiment, the product may reduce the length of the supply chain by eliminating the need for a separate film manufacturer and printer because the printing may be applied directly to the loop fabric without the need for a pre-printed film. Furthermore, the fabric of the present invention may allow for the retention of an unprinted inventory of loop fabric which may be printed on a “print to order” basis, thus, reducing industry run size requirements.
The printed loop fabric of the present invention is generally a knit fabric. The printed loop fabric is preferably formed from a warp knitting process. More specifically, the fabric may be formed from a warp knit, weft insertion fabric formation process. However, it is contemplated that the printed loop fabric may alternatively be formed from a tricot knitting process, which is another form of warp knitting.
The printed loop fabric formed from the warp knit, weft insertion process is typically comprised of warp yarns, weft yarns, and tie yarns (or chain stitch yarns). The comprising the printed loop fabric may be of any synthetic fiber type. Synthetic fibers include, for example, polyester, acrylic, polyamide, polyolefin, polyaramid, polyurethane, or blends thereof. More specifically, polyester includes, for example, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polylactic acid, or combinations thereof. Polyamide includes, for example, nylon 6, nylon 6,6, or combinations thereof. Polyolefin includes, for example, polypropylene, polyethylene, or combinations thereof. Polyaramid includes, for example, poly-p-henyleneteraphthalamid (i.e., Kevlar®), poly-m-phenyleneteraphthalamid (i.e., Nomex®), or combinations thereof.
The printed loop fabric may be comprised of a variety of fiber types such as staple fiber, filament fiber, spun fiber, or combinations thereof. The printed loop fabric can be formed from fibers or yarns of any size, including microdenier fibers and yarns (fibers or yarns having less than one denier per filament). Preferably, the yarns comprising the printed loop fabric may independently have a denier of between about 20 and about 300, and more preferably, between about 40 and about 200. Furthermore, the fabric may be partially or wholly comprised of multi-component or bi-component fibers or yarns which may be splittable along their length by chemical or mechanical action.
The yarns comprising the printed loop fabric may be exposed to a texturing process. It may be preferable that the warp yarns are textured because the texturing process generally adds bulk to the yarns, which may assist in engagement of the hooks with the loops made from the textured warp yarns. During the texturing process, it may be desirable to apply a lubricant, such as mineral oil, to the yarn prior to the start of the texturing process to assist in processing the yarn. Chemical application may be accomplished by immersion coating, padding, spraying, foam coating, or by any other technique whereby one can apply a controlled amount of a liquid suspension to the yarns.
It is also contemplated that prior to the fabric formation process, the yarns may have various other additives incorporated within them, or on them, for the purpose of imparting certain characteristics to the printed loop fabric. For example, chemicals may be added which provide antimicrobial properties, antistatic properties, pilling resistance, or abrasion resistance to the yarns, and ultimately to the final fabric formed therefrom. It is also contemplated that the yarns may be dyed in order to impart color to the printed loop fabric. Dyeing may be accomplished by any traditional method known to those skilled in the art, such as via package dyeing, solution dyeing, or beam dyeing.
Similarly, after the loop fabric has been formed, the fabric may be treated with one or more chemical finishes. For example, it may be desirable to treat the fabric with one or more chemical finishes such as water repellants, soil release agents, antimicrobial agents, antibacterial agents, anti-fungal agents, flame retardants, UV inhibitors, antioxidants, coloring agents, lubricants, anti-static agents, fragrances, and the like, or combinations thereof. Chemical application may be accomplished by immersion coating, padding, spraying, foam coating, or by any other technique whereby one can apply a controlled amount of a liquid suspension to a fabric. Employing one or more of these application techniques may allow the chemical to be applied to the fabric in a uniform manner.
Looking now to
The loop fabric 10 is a warp knit, weft inserted fabric knit on a two-bar, weft insertion warp knitting machine. As indicated in
It should be noted that the free loops in each wale alternate from one direction to the other along the wale (e.g. in
In one embodiment, a thermoplastic material 24 is extrusion coated on the back of the loop fabric 10 using a pressure roll and a chill roll to provide the desired product. Alternative methods for application may include other coating methods, such as, for example, immersion, knife/comma, roll, gravure, pad/nip, pad/vacuum, hot melt, or powder, or various laminating methods, such as with adhesive lamination or heat and pressure lamination.
As shown in
In
Printing may be accomplished by a variety of known printing techniques such as transfer printing, screen printing, digital printing, ink jet printing, flexographic printing, or any other technique that is common in the art for comparable, equivalent, traditional textile products. Flexographic printing, which may be a preferred printing method, is well known by those skilled in the art and is described, for example, in U.S. Pat. No. 5,003,873 to Lauber; U.S. Pat. No. 6,101,940 to Huff; U.S. Pat. No. 5,979,315 to Hann et al.; U.S. Pat. No. 6,408,754 to Siler et al.; and U.S. Pat. No. 5,048,418 to Hars et al., all of which are herein incorporated by reference.
The anilox cylinder 120 generally rotates at high speed such that the raised surface of the printing plate 130 contacts the anilox cylinder 120, is slightly wetted by the ink 110, and then contacts the fabric 28, thereby transferring ink 110 from the raised surface of the printing plate 130 to the fabric 28 to form a printed image on the surface of the fabric 28. Backing cylinder 180 provides adjustable pressure to the fabric 28 as it passes through the nip of the backing cylinder 180 and anilox cylinder 120. Each color used to form a printed image generally requires its own anilox cylinder, printing plate, and printing cylinder, and the colors are typically printed one after the other onto the fabric 28 as it passes through the flexographic printing machine to form printed loop fabric 50 and 60.
The pre-printed film 35 may be comprised of any thermoplastic material. Suitable thermoplastic materials include polyolefin, polyester, polyamide, polyurethane, acrylic, silicone, melamine compounds, polyvinyl acetate, polyvinyl alcohol, nitrile rubber, ionomers, polyvinyl chloride, polyvinylidene chloride, chloroisoprene, or combinations thereof. The polyolefin may be polyethylene, polypropylene, ethylvinyl acetate, ethylmethyl acetate, or combinations thereof. It may be preferable that the pre-printed film is comprised of polyethylene, polypropylene, or blends thereof. It may be even more preferable that the pre-printed film is polyethylene comprised of a blend of low density and linear low density polyethylene.
Additionally, after the steps of fabric formation, coating the fabric with a thermoplastic material, and/or lamination of the fabric with a pre-printed film, the fabric may be treated with one or more mechanical finishes. For example, it may be desirable to expose the fabric to one or more mechanical finishes such as exposure to a high friction roll, napping, brushing, sanding, exposure to water, air, or other fluid, and the like, or combinations thereof. Any one of these mechanical treatments may be used to lift any loops that may be lightly bonded in the thermoplastic material in preparation for engagement with the hooks of the mechanical closure system. Exposure to a high friction roll or a brushing roll are preferable mechanical finishing processes used for lifting the loops of the fabric, while avoiding breakage of any of the loops. It may be preferable that this step of lifting the loops of the fabric occurs as the final step in the process of creating a printed loop fabric.
Examples 1 through 4 are provided to illustrate the improvement of printed low loop fabric over printed standard loop fabric (or loop fabric having longer loops). More specifically, these Examples illustrate that the increased open space achieved by the low loop fabric provides improved clarity and visibility of the printed image which may be placed either directly on the face of the low loop fabric, on the thermoplastic material on the backside of the low loop fabric, or on a pre-printed film which may be laminated to the thermoplastic material on the backside of the low loop fabric. These embodiments are accomplished without sacrificing the hook to loop engagement strength of the mechanical closure system.
For comparison purposes,
A thermoplastic material was extrusion coated to the backside of the standard loop fabric described in Example 1 and shown in FIG. 13A. The thermoplastic material was P9H7M-026 as disclosed in Example 2 above. A pre-printed 1.25 mil polyethylene film was also extrusion coated to the thermoplastic material on the backside of the standard loop fabric. The film was available from ISO Polyfilms located in Gray Court, S.C.
The same thermoplastic material and pre-printed 1.25 mil polyethylene film as described above was extrusion coated to the backside of the low loop fabric described in Example 1 and shown in FIG. 13B. The comparison of the standard loop fabric with the low loop fabric clearly illustrates the improved visibility and clarity of the printed images contained within the pre-printed film laminated to the backside of the low loop fabric.
The same low loop fabric described above in Example 2, but without any printing, was tested for hook to loop engagement strength after exposure to a high friction roll. The fabric was tested for Peel Strength according to ASTM-D5170-98 and for Shear Strength according to ASTM-D5169-98. These two tests are indicative of the hook to loop engagement strength of fabric used in mechanical closure systems.
The hook material was purchased from YKK Corporation of Macon, Ga. under the product name, “WE”. Sample 1 was the control sample, which was not exposed to the high friction roll. Samples 2 through 4 were exposed to the high friction roll, and the direction of the high friction roll was opposite to the direction of the fabric flow through the machine. The results are shown in Table 1 below.
It is readily known to those skilled in the art of loop fabrics, and more specifically diaper loop fabrics, that acceptable peel strength results are in the range of about 200 to about 400 grams per inch of fabric and that acceptable shear strength results are in the range of about 3000 to about 4000 grams per inch of fabric. The results in Table 1 indicate that exceptional peel and shear strength are achieved for the low loop fabric after exposure to a high friction roll for the purpose of lifting loops which have been lightly bonded to the thermoplastic material. The results in Table 1 provide further illustration that the low loop fabric provides improved graphic visibility and clarity while maintaining sufficient hook to loop engagement strength as desired for the fabric's end use as the female portion of a mechanical closure system.
It can readily be seen that a printed loop fabric has been disclosed which can readily function as the female member of a hook and loop connection and which exhibits improved clarity and visibility of a printed image when compared with other similarly constructed fabrics. The process of flexographic printing the face of the fabric composite, as described in one embodiment of the invention, eliminates the need to rely upon the “see through” characteristics of the fabric, adhesive, or film comprising the product, in order to see the printed image, thereby providing improved clarity and visibility of the printed image. Because of the increased openness between the yarns comprising the low loop fabric, the process of printing on the thermoplastic material on the backside of the fabric results in a printed loop fabric having improved graphic clarity and visibility. Similarly, laminating a pre-printed film to the thermoplastic material on the backside of a low loop fabric results in improved clarity and visibility of the pre-printed image contained within the film.
Furthermore, the printed loop fabric does not readily tear due to the weft inserted yarn that provides stability in the weft direction of the fabric, and backcoating the fabric with a thermoplastic material provides stability to the fabric and does not tie down all of the loops of the fabric thereby preventing the destruction of the retention power or the ease of releasement of the hook and loop connector. Additionally, the printed loop fabric is relatively inexpensive, simple, and straight forward to manufacture.
These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the scope of the invention described in the appended claims.
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Number | Date | Country | |
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20040099019 A1 | May 2004 | US |