WO2012018971A2

WO2012018971A2 - Female part of hook and loop fastener

Info

Publication number: WO2012018971A2
Application number: PCT/US2011/046531
Authority: WO
Inventors: Kenichiro Morishita
Original assignee: 3M Innovative Properties Company
Priority date: 2010-08-06
Filing date: 2011-08-04
Publication date: 2012-02-09
Also published as: CN103052332B; TW201211338A; JP2012034802A; TWI612192B; EP2600746A2; EP2600746A4; KR101845105B1; CN103052332A; WO2012018971A3; JP5841318B2; KR20130095269A

Abstract

The present invention is a female part of a hook and loop fastener comprising a substrate and a knitted fabric constituted of warp yarns, weft yarns and loop yarns, wherein the warp, weft, and loop yarns are interwoven to form interlacing points, and the warp yarn forming the interlacing point progresses in a direction opposite to that of the loop yarn forming the interlacing point and the weft yarn forming the interlacing point. The female part of the hook and loop fastener exhibits excellent engaging force with a male part, where the left-right engaging force difference is small.

Description

FEMALE PART OF HOOK AND LOOP FASTENER

TECHNICAL FIELD

The present invention relates to a female part of a hook and loop fastener, to a hook and loop fastener having the female part, and to an absorbent article having the hook and loop fastener.

BACKGROUND

Hook and loop fasteners are widely used for fastening flooring material, in open/close application for clothes, etc., and also for engagement of absorbent articles such as diapers because of the simplicity of the attaching/detaching operation. A hook and loop fastener is made up of a male part and a female part that engages therewith. Specifically, a loop constituting the female part is held in place by engaging with a hook constituting the male part. In the prior art, attempts have been made to develop female parts of sufficient engaging force with the male parts.

U.S. Patent No. 6,096,667 describes a weft inserted warp knit fabric for use as the female fabric in a hook and loop fastener comprising: a weft inserted warp knit fabric having a face side and a back side, said back side of said fabric having a plurality of spaced wales of stitches with a lap portion of each of said stitches projecting outwardly therefrom to form a free loop connected only at its base to its respective wale with adjacent loops in each wale tilted sidewise alternately in opposite directions and a weft yarn inserted into the courses of the fabric between the face and back side of the fabric and extending across the full width of the fabric.

Japanese Unexamined Patent Application Publication No. 2004-236960 A describes a female material piece for a hook and loop fastener, having a structure wherein it is joined to a substrate surface via a warp knit fabric that has loops formed to receive hooks, wherein the warp knit fabric is made up of loop pile stitching engaged with racked stitching by yarn threaded through a middle guide bar and with racked stitching by yarn threaded through a rear guide bar such that the direction of adjacent loop piles in the knitting direction alternates between right and left, and of base stitching engaged by yarn threaded through a front guide bar with racked stitching or loop pile stitching, respectively.

WO 2010-030548 describes a female part of a hook and loop fastener comprising a substrate and a knitted fabric composed of warps, wefts and loop yarns, wherein a structure of the warps is a chain stitch on which open and close nodes are alternately arranged, the loop yarns are only fixed to the close nodes of the warp yarns with open nodes of the loop yarn, and the loop yarns project in right and left directions alternately in a direction of the warps, from only one surface of the knitted fabric.

SUMMARY OF THE INVENTION

The present invention is a female part of a hook and loop fastener comprising a substrate and a knitted fabric composed of warp yarns, weft yarns, and loop yarns, wherein the warp, weft, and loop yarns are interwoven to form interlacing points, and the warp yarn forming the interlacing point progresses in a direction opposite to that of the loop yarn forming the interlacing point and the weft yarn forming the interlacing point. The female part of the hook and loop fastener exhibits excellent engaging force with a male part, where the left-right engaging force difference is small.

The female part of a hook and loop fastener of the present invention may adopt a construction wherein the loop yarns project alternately right and left with regards to the warp yarns from one side of the knitted fabric. Furthermore, "rear leakage" is not prone to occur in the loop yarns projecting from the female part of a hook and loop fastener (i.e., the piles of the loop yarns formed on one side of the knitted fabric constituting the female part of a hook and loop fastener are formed on the opposite side of the knitted fabric) either during the manufacture of the female part of a hook and loop fastener (the knitted fabric) or even after a particular amount of time has passed. Thus, the female part of a hook and loop fastener obtained according to the present invention has excellent engaging force for engaging with a male part, and the left-right engaging force difference is small. Also, by applying a knitting pattern to the female part of a hook and loop fastener of the present invention, the tearing strength of the female part of a hook and loop fastener can be improved. Furthermore, the female part of a hook and loop fastener according to the present invention can be readily produced, and can be advantageously used as a female part for a hook and loop fastener in an absorbent article such as a paper diaper.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the structure of the cross-section of a female part of a hook and loop fastener according to an embodiment of the present invention;

FIG. 2 A is a schematic view showing a knitting pattern of the knitted fabric in the female part of a hook and loop fastener of an embodiment (Examples 1 and 3) of the present invention;

FIG. 2B is a schematic view showing the state of loop yarns (one loop each for left and right) formed on the knitted fabric and observed when the knitted fabric was cut along the line A-A of FIG. 2A (perpendicular to the warp direction);

FIG. 3 A is a schematic view showing a pattern illustrating one aspect of the knitting pattern for the knitted fabric shown in FIG. 2A; FIG. 3B is a schematic view showing the pattern of knitting texture of the knitted fabric shown in FIG. 3A, as decomposed into warp yarns, weft yarns and loop yarns, showing (a) loop yarns, (b) warp yarns, and (c) weft yarns;

FIG. 4 is a schematic view showing the structure of the cross-section of the hook and loop fastener according to an embodiment of the present invention;

FIG. 5 A is a schematic view showing a knitting pattern of a knitted fabric in a female part of a hook and loop fastener according to an embodiment (Example 2) of the present invention;

FIG. 5B is a schematic view showing the state of loop yarns (one loop each for left and right) formed on the knitted fabric and observed when the knitted fabric was cut along the line B-B of FIG. 5 A (perpendicular to the warp direction);

FIG. 6 is a schematic view showing a pattern illustrating one aspect of a knitting pattern for the knitted fabric shown in FIG. 5A;

FIG. 7 A is a schematic view showing a knitting pattern of a knitted fabric of a female part of a hook and loop fastener according to an embodiment (Example 4) of the present invention;

FIG. 7B is a schematic view showing the state of loop yarns (one loop each for left and right) formed on the knitted fabric and observed when the knitted fabric was cut along the line C-C of FIG. 7A (perpendicular to the warp direction);

FIG. 8 is a schematic view showing a pattern illustrating one aspect of a knitting pattern for the knitted fabric shown in FIG. 7A;

FIG. 9 is a schematic view showing the state of loop yarns formed on the surface of the knitted fabric of the female part of a hook and loop fastener of comparative example i;

FIG. 10 is a schematic view of a test sample used in measuring tearing strength; FIG. 11 A is a frontal view of a method of fastening a test sample used in measuring tearing strength to a tensilon tensile tester and the direction in which it is pulled; and

FIG. 1 IB is a side view of a method of fastening a test sample used in measuring tearing strength to a tensilon tensile tester and the direction in which it is pulled.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in detail below with reference to drawings showing an embodiment thereof. However, the female part of a hook and loop fastener according to the present invention is not limited to the embodiment that follows.

As illustrated schematically in FIG. 1, a female part 10 of a hook and loop fastener according to the present invention has a knitted fabric 20 composed of warp yarns 21 (not shown), weft yarns 22 (not shown) and loop yarns 23, as well as a substrate 30. In a knitted fabric 20, the loop yarns 23 form piles in the knitted fabric 20, and warp yarns 21 and weft yarns 22 form base stitching 25 of the knitted fabric 20, with the loop yarns 23 projecting from one surface of the knitted fabric 20 alternately in the left and right direction relative to the warp yarns 21.

FIG. 2 A is a schematic view showing the knitting pattern of the knitted fabric 20 with the construction illustrated in FIG. 1, FIG. 3 A is a schematic view showing one aspect of the knitting pattern of FIG. 2A, and FIG. 3B is a view showing the pattern of knitting texture of FIG. 3 A decomposed into warp yarns 21 ((b) in FIG. 3B), weft yarns 22 ((c) in FIG. 3B), and loop yarns 23 ((a) in FIG. 3B). As shown in FIGs. 2A and 3A, the warp yarns 21, weft yarns 22, and loop yarns 23 of the knitted fabric 20 are interwoven to form interlacing points 24 (24a, 24b, 24c). Here, the warp yarn 21 forming the interlacing point 24 progresses in a direction opposite to that of the loop yarn 23 forming the interlacing point 24 and the weft yarn 22 forming the interlacing point 24. By having such a knitting pattern, a construction wherein the loop yarns 23 project from one surface of the knitted fabric 20 alternately to the left and to the right relative to the warp yarns 21 is obtained (see FIG. 2B). Also, a construction is possible that prevents "back leakage" of the loop yarns as described above.

A knitting pattern of the knitted fabric 20 will be described below with reference to FIGs. 3A and 3B. However, the knitting pattern of the knitted fabric 20 is not limited to that illustrated in FIGs. 3A and 3B.

First, warp yarns 21 are formed by repeated chain stitching in a 0-1/1-0/1-0/0-1 pattern, and the warp yarns 21 forming the base stitching 25 (middle guide bar) of the knitted fabric 20.

Next, loop yarns 23 are guided to the left and to the right relative to the warp yarns 21 to form a pile (front bar) in the knitted fabric 20. The loop yarn 23 is first wrapped at a predetermined needle position of the knitted fabric 20 from right to left by a closed node or an open node and guided to the left. Then, the leftwards fed loop yarn 23 is reverse-wound to engage the open node 21a of the warp yarn 21 (that is, the loop yarn becomes a closed node), forming the interlacing point 24a. Thus, the warp yarn 21 forming the interlacing point 24a progresses in a direction opposite to that of the loop yarn 23 forming the interlacing point 24a. The loop yarn 23 is then further guided to the left of the knitted fabric 20. Then, the loop yarn 23 is wrapped at a predetermined needle position of the knitted fabric 20 from left to right by a closed node or an open node. Then, the rightwards-fed loop yarn 23 is reverse-wound to engage the open node 21b of the warp yarn 21 (that is, the loop yarn becomes a closed node), forming the interlacing point 24b. As described above, the warp yarn 21 forming the interlacing point 24b also progresses in a direction opposite to that of the loop yarn 23 forming the interlacing point 24b. This is repeated so that the loop yarns 23 project from one surface of the knitted fabric 20 alternately to the left and to the right relative to the warp yarns 21 to form a pile.

As illustrated in FIG. 2B, the expression "the loop yarns project from only one surface of the knitted fabric alternately to the left and to the right relative to the warp yarns" here means that in the knitted fabric 20, when a cross section perpendicular to the direction of the warp yarns 21 is viewed, loop yarns 23 are formed alternately to the left and to the right while maintaining a constant angle relative to the surface of the base stitching 25 with the point of engagement with the warp as the origin. Therefore, loop yarns that are formed approximately parallel to the surface of the base stitching (that is, the loop yarns which lie on the surface) are not included even if the loop yarns are formed to the left and to the right relative to the warp yarns.

In FIGs. 3A and 3B, the pattern of the loop yarns 23 is represented by a repetition of 6-5/11-10/5-6/0-1 (open nodes on left and right ends). Other pattern examples include

6- 5/10-11/5-6/1-0 (when the left and right ends form closed nodes in the aspect of FIG. 3A), 5-4/9-8/4-5/0-1 (aspect of FIG. 6, left and right ends are open nodes), and 5-4/8-9/4-

5/1-0 (when the left and right ends of the aspect of FIG. 6 form closed nodes).

Next, the weft yarns 22 coupled with the warp yarns 21 form the base stitching 25 (rear bar) of the knitted fabric 20. In FIGs. 3A and 3B, the weft yarn 22 is inserted into the chain stitching of the warp yarn 21 as stitches in the pattern 4-3/7-7/3-4/0-0. Apart from the aspect shown in FIG. 3A, the stitches may for instance be inserted in the pattern

7- 6/13-13/6-7/0-0 (aspect of FIG. 6) or 3-2/5-5/2-3/0-0. The weft yarn 22 is reverse- wound to engage with the open node of the warp yarn 21 in the interlacing point 24a (i.e. the weft yarn forms the closed node), and like the loop yarns, the warp yarn 21 forming the interlacing point 24a progresses in a direction opposite that of the weft yarn 22 forming the interlacing point 24a. In the aspects of FIGs. 2, 3 A and 3B, the weft yarn 22 is woven in at the open node of the warp yarn 21, and the weft yarn 22 changes directions to the left and right at the closed node of warp yarn 2 adjacent to the warp yarn 21.

In this way, the warp yarn 21, weft yarn 22, loop yarn 23 of the female part 10 of a hook and loop fastener are woven together to form the interlacing point 24, and the warp yam 21 forming the interlacing point 24 progresses in a direction opposite to that of the loop yam 23 forming the interlacing point 24 and the weft yam 22 forming the interlacing point 24.

As is clear from FIGs. 3A and 3B, the knitted fabric 20 has a construction wherein the warp yam 21 has alternating interlacing points 24 and points of intersection between the warp yam and the weft yam. Also, as described above, the loop yams 23 project from one surface of the knitted fabric 20 alternately to the left and to the right relative to the warp yams 21. From considerations of engaging force, the angle of the projecting loop yams 23 relative to the knitted fabric 20 is preferably 30° or more relative to the surface of the knitted fabric, and may be 45° or more in a certain aspect. Also, the upper-bound of the projecting angle has no special limitation, and the angle of the projecting loop yams 23 relative to the surface of the knitted fabric 20 may be 80° or even 90°.

Here, by designating a specific form of the node of the warp yams 21, weft yams 22, and loop yams 23 in three successive interlacing points 24 (i.e., open node or closed node), the knitting pattern can be defined. In other words, the forms of the nodes of the warp yams 21, weft yams 22, and loop yams 23 in three successive interlacing points 24 in the warp direction constitute minimum units 26 for defining the knitting pattern of the knitted fabric 20. Also, as shown in FIGs. 2A and 3A, the interlacing points 24 (24a, 24b, and 24c) and the nodes of the warp yams (closed nodes, not interlacing points) alternate along the warp yam. Thus, the knitted fabric illustrated in FIGs. 2 A and 3 A include three interlacing points and two warp yarn nodes (closed nodes) in the warp direction as minimum units defining the knitting pattern.

In order to form the loop piles effectively and obtain a construction with reduced risk of "back leakage", the warp yarn 21, weft yarn 22, and loop yarn 23 in the three successive interlacing points 24 preferably each have the knitting patterns illustrated in Table 1. In Table 1, O represents an open node and C represents a closed node. For instance, "C-C-C" indicates that the forms of the nodes in three successive interlacing points are closed node/closed node/closed node.

Table 1

Among the patterns described above, one of the patterns 1 through 18 is favorably adopted as the knitting pattern in an aspect. From the perspective of reducing the risk of "back leakage", the knitting pattern is more preferably one of patterns 1 through 9, and especially preferably one of patterns 1 through 3.

The knitting machine used for knitting the knitted fabric 20 is not particularly limited, and any knitting machine with three bars or four bars widely used conventionally can be used without modification. Thus, the female part of a hook and loop fastener of the present invention can be easily produced at low cost.

The material of the warp yarns 21, weft yarns 22, and loop yarns 23 constituting the knitted fabric 20 is not particularly limited, and may include polypropylene, polyester, polyethylene, polyamide, polyurethane, rayon, copolymers or mixtures thereof, and natural fiber, etc. In an aspect, from considerations of preventing damage of the female part due to engagement with a male part, high-strength polyamide may be used. From considerations of material cost and environmental stability, polyester may be used. As loop yarns, multi-filament yarns are preferred to mono-filament yarns in order to increase a probability that engaging with a male part occurs. In this case, since a loop yarn of thin filaments may sometimes be broken during engagement with the male part, a loop yarn of suitable diameter should be selected based on the shape, etc., of the hook and loop fastener. As regards warp yarns and weft yarns, both mono-filament and multi-filament yarns may be used. In general, the filament density of the yarn is from 20 to 220 T, more preferably from 20 to 100 T.

In one aspect, the knitted fabric 20 may have a basis weight of 10-100 g/m². If the basis weight is 5 g/m² or less, the shape of the knitted fabric may be difficult to maintain when knitting, and if the basis weight is 100 g/m² or more, rigidity is increased so that, when attached to an absorbent article, flexibility may be impaired in that portion. Also, the knitted fabric may become too dense, and when the substrate is designed aesthetically, visibility may be impaired. Since the female part 10 of a hook and loop fastener of the present invention has excellent engaging force for engaging with a male part and left-right engaging force difference is small, the basis weight can be reduced as compared to conventional products. Therefore, a female part of a hook and loop fastener having excellent visibility can be produced at low cost.

Additional processing such as raising, embossing, printing, dyeing, coloring, and the like may be performed on the female part 10 of a hook and loop fastener. The knitted fabric 20 may be dyed in all or in part. Especially when used as a member of an absorbent article such as a diaper, gloss such as luster, shining, etc., can be diminished and aesthetically excellent appearance can be obtained.

The material for the substrate 30 is not particularly limited, and resin film, non- woven fabric, paper, or laminates thereof may be used. Examples of resin films include, for example, synthetic resin films of polypropylene, polyethylene, polystyrene, polyethylene terephthalate and other polyester resins; polyamide resins; and polyurethane resins, or laminates of these synthetic resin films. In one aspect, a position indicator for the surface where a male part is engaged, or various symbols or designs may be provided on the surface of the substrate.

The substrate 30 is joined to the knitted fabric 20 on the surface opposite to the surface from which the loop yarns 23 project alternately to the left and the right. The method of joining the substrate 30 to the knitted fabric 20 is not particularly limited. Any conventionally known method such as dry lamination, extrusion lamination, wet lamination, thermal lamination, ultrasonic method, may be used. Among them, a dry lamination method is preferable from considerations of productivity, flexibility, visibility of position indicator or the like provided on the substrate layer. As an adhesive for dry lamination, urethane based adhesive, EVA based adhesive, acrylic adhesive, vinyl acetate based adhesive or the like may be used. As an adhesive for wet lamination, an adhesive based on starch, casein, vinyl acetate, polyacrylic ester, or the like may be used. For extrusion lamination, resins such as polyethylene, polypropylene, or a modified polyolefm may be suitably used. The adhesive or resin is not limited to those mentioned above.

In the case of dry lamination, an adhesive layer may be provided on one surface of the substrate all over the entire surface, or may be provided partially. When the adhesive layer is provided partially, there is no special restriction on the method of application. In general, an adhesive is applied in patterns, with no particular restriction on the pattern, shape, size, etc., of application. Any pattern, shape or size, for example, a circle, an ellipse, a rectangle, a polygon, etc., may be employed. When an adhesive is applied partially on the surface of the substrate, the number of loop yarns caused to lay down due to seepage of adhesive through the knitted fabric can be reduced, so that a decrease in engaging force when engaging with hooks constituting the male parts can be avoided. By suitably selecting the shape of the application pattern and the amount of adhesive, the engaging force can be varied.

As illustrated in FIG. 4, the female part 10 of a hook and loop fastener of the present invention may be used to form a hook and loop fastener 50 by being engaged with a male part 40. Here, the loop yarns 23 (piles) provided on the knitted fabric 20 constituting the female part 10 of a hook and loop fastener catch the hooks 41 constituting male parts 40, so that the female part 10 engages with the male part 40 and the female and the male parts are adhered to each other. In the hook and loop fastener 50 having the female part 10 of a hook and loop fastener of the present invention, since the female part is constructed such that the loop yarns 23 project from one surface of the knitted fabric 20 alternately to the left and the right relative to the warp yarns 21 and there is little risk of "back leakage" of the loop yarns, the left-right engaging force difference when engaging with the male part tends to be suppressed. Here, the left-right engaging force difference can be evaluated by engaging a female part of a hook and loop fastener with a male part, measuring the engaging force when the two are peeled off from right to left (right engaging force) and the engaging force when the two are peeled off from left to right (left engaging force), with respect to the width direction (i.e. the CD direction, the direction perpendicular to the warp direction), for a plurality of points, and obtaining the absolute value of the result calculated by: {(the mean of the measured right engaging force) - (the mean of the measured left engaging force)} /(the mean of all the measured values of right engaging force and left engaging force). The nearer the value thus obtained is to zero, the smaller the left-right engaging force difference.

The male part may be of any type as long as satisfactory engaging force can be obtained. For example, a male part having a mushroom-shaped hook, a key-shaped hook, or a J-shaped hook can be used. The pin density of the male part is not particularly specified, but is generally in a range of from 500 to 5000 pins per square inch, and in one aspect, a male part having a pin density of 1600 pins per square inch may be used. The material of the male part may be selected, as in the case of the yarns constituting the female part, from polypropylene, polyester, polyethylene, polyamide, copolymers or mixtures thereof. The thickness of the substrate portion of the male part can be suitably set. Specifically, a hook tape commercially available from Sumitomo 3M (CS-600) etc., can be used.

The hook and loop fastener of the present invention can be used as a fastener of floor material or wall material, a fastener of clothes, a fastener for cleaning members, or a fastener for car interior materials. It can also be used as a fastener of absorbent articles such as paper diapers, sanitary napkins, breastfeeding pad, etc. When the hook and loop fastener is used for an absorbent article, especially a paper diaper, engaging characteristics of the female part and male part, in particular performance of the female part should be considered. In ordinary paper diapers, a pair of male parts is provided on both sides of the wearer's back, and a pair of female parts is provided on the left and right of front body for abdomen. Thus, the paper diaper has the male parts and female parts to be engaged at two locations each on the left and right. If the left-right engaging force difference, that is, the difference between the forces required to peel off to the left direction and the right direction, is large, the wearer may feel anxiety regarding the reliability of the fastening function of the paper diaper provided by the hook and loop fastener. The female part of the present invention is preferable because it enables a reduction in the left-right engaging force difference with the male part.

When the female part of a hook and loop fastener of the present invention is used in a hook and loop fastener for an absorbent article, means for fastening to such absorbent article may include adhesion by means of, for example, gluing, thermal fusion, or ultrasonic bonding; integral molding, mechanical fastenings such as sewing and stapling, and so forth. For fastening by means of gluing, known adhesives such as rubber based adhesives such as SIS and SBS, acryl based adhesives, silicone based adhesives, EVA based adhesives, and the like may be suitably selected as required, but the adhesive is not limited to those resins.

Examples

Examples of the present invention will be described in further detail below. It is to be understood that the present invention is not limited to these examples.

Example 1

A tricot pile knitted fabric having a knitting pattern of loop yarns (6-5/11-10/5- 6/0-1), warp yarns(0-l/l-0/l-0/0-l), and weft yarns (4-3/7-7/3-4/0-0) was produced using a three-bar knitting machine (made by KARL MAYER). The materials used for the loop yarns, warp yarns, and weft yarns were: loop yarns: polyester (84T, 36 threads^ warp yarns: polyester (22T, 1 thread), weft yarns: polyester (56T, 24 threads). Knitting conditions were l-in-2-out, course: 8/cm, wales: 3.7/cm, with a basis weight for the knitted fabric of 23g/m2.

The knitted fabric thus obtained was dry-laminated to a biaxial oriented

polypropylene substrate of 12 μιη in thickness, using a polyurethane adhesive to obtain a female part of a hook and loop fastener. The knitting pattern (texture) of the knitted fabric of the female part of a hook and loop fastener thus obtained is schematically shown in FIG. 2A, the pattern thereof is schematically shown in FIG. 3A, respectively. FIG. 2B is a schematic view showing the state of the loop yarns (one loop each for left and right) formed in the knitted fabric, which is observed when the knitted fabric was cut along the line A-A of FIG. 2A (a direction perpendicular to a warp direction). The adhesive was formulated by mixing polyurethane main component (Trade name: TAKELAC A969v, manufactured by Mitsui Chemical Polyurethane Co.) and isocyanate curing agent (Trade name: TAKENATE A5, manufactured by Mitsui Chemical Polyurethane Co.) and then adding the mixture to silica (Trade name: TOKUSIL U, manufactured by Tokuyama Co.), with the amount of silica in solid being 7% by weight based on total weight of the adhesive. Specifically, to a solvent containing silica stirred therein, polyurethane main component and isocyanate curing agent were added, and after further stirring, the mixture was laminated at 150 m/min using a dry laminator manufactured by FUJI SEIKI Co. The amount of applied adhesive was about 5 g/m2.

Example 2

As in Example 1 , a tricot pile knitted fabric having a knitting pattern of loop yarns (5-4/9-8/4-5/0-1), warp yarns(0-l/l-0/l-0/0-l), and weft yarns (7-6/13-13/6-7/0-0) was produced using a three-bar knitting machine (made by KARL MAYER). The materials used for the loop yarns, warp yarns, and weft yarns were: loop yarns: polyester (56T, 24 threads), warp yarns: polyester (22T, 1 thread), weft yarns: polyester (22T, 1 threads). Knitting conditions were l-in-2-out, course: 8/cm, wales: 3.7/cm, with a basis weight for the knitted fabric of 14g/m2. As in example 1, the obtained knitted fabric was used to obtain a female part of a hook and loop fastener. The knitting pattern (texture) of the knitted fabric of the female part of a hook and loop fastener thus obtained is schematically shown in FIG. 5A, and the pattern thereof is schematically shown in FIG. 6, respectively. FIG. 5B is a schematic view showing the state of the loop yarns (one loop each for left and right) formed in the knitted fabric as observed when the knitted fabric was cut along the line B-B of FIG. 5 A (the direction perpendicular to the warp direction). Example 3

A tricot pile knitted fabric having a knitting pattern of loop yarns (6-5/11-10/5- 6/0-1), warp yarns (0-1/1-0/1-0/0-1), and weft yarns (4-3/7-7/3-4/0-0) was produced using a three-bar knitting machine (made by KARL MAYER). The materials used for the loop yarns, warp yarns, and weft yarns were: loop yarns: polyester (56T, 24 threads), warp yarns: polyester (22T, 1 thread), weft yarns: polyester (22T, 1 thread). Knitting conditions were l-in-2-out, course: 8/cm, wales: 3.7/cm, with a basis weight for the knitted fabric of 12g/m2. As in example 1, the obtained knitted fabric was used to obtain a female part of a hook and loop fastener. The knitting pattern of the knitted fabric of the female part of a hook and loop fastener thus obtained and the state of the loop yarns formed in the knitted fabric was the same as in Example 1.

Example 4

A tricot pile knitted fabric having a knitting pattern of loop yarns (6-5/11-10/5- 6/0-1), warp yarns (0-1/1-0/1-0/0-1), and weft yarns (3-2/5-5/2-3/0-0) was produced using a three-bar knitting machine (made by KARL MAYER). The materials used for the loop yarns, warp yarns, and weft yarns were: loop yarns: polyester (56T, 24 threads), warp yarns: polyester (22T, 1 thread), weft yarns: polyester (22T, 1 thread). Knitting conditions were 1-in-l-out, course: 8/cm, wales: 5.5/cm, with a basis weight for the knitted fabric of 25g/m2. As in example 1, the obtained knitted fabric was used to obtain a female part of a hook and loop fastener. The knitting pattern (texture) of the knitted fabric of the female part of a hook and loop fastener thus obtained is schematically shown in FIG. 7A, and the pattern thereof is schematically shown in FIG. 8, respectively. FIG. 7B is a schematic view showing the state of the loop yarns (one loop each for left and right) formed in the knitted fabric, which is observed when the knitted fabric was cut along the line C-C of FIG. 7A (a direction perpendicular to a warp direction).

Comparative Example

1 A tricot pile knitted fabric having a knitting pattern of loop yarns (3-2/5-4), warp yarns (1-0/0-1), and weft yarns (0-0/5-5) was produced using a three-bar knitting machine (made by KARL MAYER). The materials used for the loop yarns, warp yarns, and weft yarns were: loop yarns: polyamide (44T, 11 threads), warp yarns: polyamide

(22T, 1 thread), weft yarns: polyamide (22, 1 thread). Knitting conditions were 1-in-l-out, course: 10.4/cm, wales: 5.5/cm, with a basis weight for the knitted fabric of 21g/m2. As in example 1 , the obtained knitted fabric was used to obtain a female part of a hook and loop fastener. FIG. 9 is a schematic view showing the state of the loop yarns (one loop each for left and right) formed in the knitted fabric, which was observed when the knitted fabric was cut in a direction perpendicular to the warp direction of the knitted fabric.

Evaluation of a female part of a hook and loop fastener

Engaging force

On the female part of a hook and loop fastener obtained in the examples and comparative examples described above, a male part (CS-600, manufactured by Sumitomo 3M Ltd.) of 25 mm in width, was placed and press bonded with a 2 kg roller. Then, the female part and the male part were pulled in the horizontal direction with a force of 1 kg to cause both to engage with each other. The engaged male part and female part of a hook and loop fastener were stretched in vertical direction at stretching rate of 300 mm/min, and the peeling force at the time of peeling-off was measured to obtain the engaging force (N/25 mm). The engaging force was measured by peeling off the engaged female part of the hook and loop fastener from the male part either from right to left (right engaging force) or left to right (left engaging force) relative to the width direction (that is, CD direction, perpendicular to the warp direction), each six times. The engaging force was obtained by averaging 12 measured values. The results are shown in Table 2.

Direction of the engaging force

The direction of the engaging force was obtained from six measured values each of the right engaging force and the left engaging force measured as described above, using the equation: {(mean of six measured right engaging force) - (mean of six measured left engaging force)} / (mean of all (twelve) measured right engaging force and left engaging force) and expressing the result as an absolute value. The closer the value to zero, the smaller the left-right engaging force difference. The results are shown in Table 2.

Delamination strength

The knitted fabric of the female part of a hook and loop fastener and the substrate were bonded each other with an adhesive, and then set at 25 mm inter-chuck and stretched in the vertical direction at stretching rate of 300 mm/min, and the force at the time of separation of the knitted fabric and the substrate was measured by using a Tensilon tensile tester to obtain the delamination force (N/25 mm). The results are shown in Table 2. Tearing strength (longitudinal direction) The obtained female part of a hook and loop fastener was cut to approx. 100 mm (MD) x 50 mm (CD) and a 20 mm deep notch 70 was cut at substantially the center of the CD direction by a blade to produce a test sample 60 (test sample A) as shown in FIG. 10. Another test sample (test sample B) was produced using the same method. As shown in FIGs. 11A and 1 IB, ends 61a and 61b on the side of the test sample A with the notch 70 were fastened to a Tensilon tensile tester set at 20 mm between chucks 80, the test sample A was stretched for 100 mm at a rate of 300mm/min, and the change in strength of the test sample A was measured. The highest strength value obtained was designated the tearing strength of the test sample A. The test sample B was set at a tearing direction opposite to that of test sample A (end 61b fastened to an upper chuck 80, end 61a fixed to a lower chuck 80), and the tearing strength of the test sample B was measured under the same conditions as above. The tearing strengths of the test samples A and B were averaged to obtain the tearing strength of the female part of a hook and loop fastener. The results are shown in Table 2.

Proj ection of loop yarns

The projection state of the loop yarns on the female part of a hook and loop fastener was observed visually. A condition in which the loop yarns projected to the left and right and the loops on the left and right had equal sizes was judged "good", a condition in which the loop yarns projected to the left and right but the loops on the left and right did not have equal sizes was judged "acceptable", and a condition in which the loop yarns did not project to the left and right was judged "unacceptable". The results are shown in Table 2.

"Back leakage" in loop yarns

A 100 mm by 100 mm female part of a hook and loop fastener sample was prepared, and the degree of "back leakage" of the loop yarns was observed visually. "Back leakage" of 5% or less was judged "excellent", from 5 to 10% was judged "good", and from 10 to 30%> was judged "acceptable". The results are shown in Table 2.

Table 2

Claims

WHAT IS CLAIMED IS:

1. A female part of a hook and loop fastener comprising:

a substrate and a knitted fabric composed of warp yarns, weft yarns and loop yarns, wherein the warp, weft, and loop yarns are interwoven to form interlacing points, and the warp yarn forming the interlacing point progresses in a direction opposite to that of the loop yarn forming the interlacing point and the weft yarns forming the interlacing point.

2. A hook and loop fastener comprising the female part according to claim 1 and a male part.

3. An absorbent article comprising the hook and loop fastener according to claim 2.