MXPA99003032A - J hook-type hook strip for a mechanical fastener - Google Patents

Abstract

A method of making a hook strip having J-shaped hooks that can be used as a mechanical fastener. The method includes using an initial substrate of material formed as an array of upstanding precursor stems having distal tips at their ends opposite a backing. In addition, a heat source adapted for heating and a mechanism for deforming stem tips is provided. The substrate is positioned relative to the heat source such that a portion of the upstanding stems on the array is heated. Subsequently, the substrate is moved to a position relative to the mechanism for deforming to create a hook strip of J-shaped hooks from the heated portion of the upstanding stems. In addition, an article of manufacture, made in accordance with the method, is provided which includes a hook portion of a hook-and-loop type of mechanical fastener.

Description

METHOD FOR MAKING A HOOK TYPE STRIP The present invention relates generally to mechanical fasteners such as hook-loop fasteners. More particularly, the invention relates to hook straps of the J-shaped hook type such as those which can releasably close a garment, for example, a disposable garment such as a diaper or a hospital garment when it is adhered to a suitable clip type material. The hook-loop fasteners are widely used as garment fasteners. Commercial examples of these fasteners include those marketed under the trademark VELCRO by Velero USA Incorporated and under the trademark SCOTCHMATE by Minnesota Mining and • Manufacturing Company, St. Paul, Minnesota; Such fasteners are manufactured by a variety of methods. The first versions of the hook materials, still available today, are indicated in U.S. Patent Nos. 2,717,437 and 3,009,235 (both from DeMestral), in which a hook strip is made from specific warps of a Straight pile type nylon clip. One end of each clip is cut to leave an open-ended J-shaped hook, which is available to act as a fastener. ref. 29730 U.S. Patent No. 3,594,865 (Erb) discloses an injection molding technique for manufacturing a J-shaped hook strip of a hook-loop fastener. The indicated technique is the use of a closed "loop material" that has a large number of low "wire arrays" separated in the loop material. While a vacuum is applied to evacuate the "wire dies", the closed loop is passed through an extruder that forces the molten plastic, such as nylon, into the dies while also impregnating a fabric fabric immediately below the material of loop. When leaving the extruder, the excess resin is removed from the surface, from the wire matrices. The resilient hooks then gradually emerge from the dies, providing an ordered set of hooks projecting from a cloth fabric impregnated with plastic. Instead of using a fabric weave, the apparatus can be modified to create a space beyond the wire arrays into which the molten plastic can flow to form a fully plastic reinforcement for the hooks. Another U.S. Patent No. 3,594,863 (Erb) refers to a similar apparatus for producing a similar hook support strip. These patents stipulate that the disclosed method can produce a greater variety of shapes than a traditional solid matrix which is limited to the narrowing shapes from the base to the tip. However, this method would be limited in the same way to the shapes that should be narrowed inward except in this case, from an outer surface to an opposite surface along the length of the hook. It is also difficult to impregnate the polymer in the support fabric behind the "loop material". In United States Patent No. 3,718,725 (Hamano), the fastener in hook strip of a hook-loop type mechanical fastener is made from a fabric that has an ordered set of straight clips. After inserting the rods into the rows of loops to maintain their straight position, plates or rollers apply heat and pressure to fuse each clip at its apex and to press each free molten end in order to form a button or head that can be interconnected with the fastener strip of a hook-loop fastener. Because the buttons or heads have a mushroom appearance, this type of hook fastener is called "mushroom type". The hook fasteners of the mushroom type are sometimes designed so that two strips of the same hooks can be held together. These types of mechanical fasteners with auto-coupling, of the fungus type, are shown in U.S. Patent No. 3,192,589 (Pearson) which denominates the "hermaphrodite" fastener because its head lugs have both male and female characteristics when interconnected in the form of a mesh. Pearson fasteners can be made by molding a base from which integral projections without a head are projected and subsequently softening the tips of the projections with heat. Hermaphroditic mechanical fastener type fungus shown in United States Patent No. 4,290,174 (Kalleberg) is made with resilient, flexible, U-shaped monofilaments. The "central loop portion" of each monofilament is embedded in a flexible bonding layer so that the two monofilament rods project normally from the surface of the monofilament. link layer. There is a fungus-like head at the tip of each rod formed by heating the terminal ends of the monofilaments, preferably formed of a polyolefin. The rods are preferably spaced substantially uniformly and are of substantially equal length. The maximum disengagement force is achieved when the spacing between the adjacent heads is less than their diameters and the minimum required for hooking. U.S. Patent No. 3,408,705 (Kayser et al.) Also shows mushroom-type mechanical fasteners having mushroom-type heads of various shapes. "Balloon" heads (for example, fungus shaped) are formed by heating cylindrical rods. The heads in the form of hooks in J are formed by heating rods with wedge-shaped terminal ends. Another method for continuously casting a strip of J-shaped hooks is described in U.S. Patent No. 3,762,000 (Menzin et al.). The process uses mold plates with cavities to mold straight J-shaped hook members or pile-like formations. The moldable plastic material is applied in two steps, first under high pressure to form the pile-like formations of J-shaped hooks while still being in the cavities and, secondly, under a lower pressure to form the strip that it constitutes a base member so that the protrusions of the J-hook type adhere in an integral manner. U.S. Patent No. 5,260,015 (Kennedy et al.) Alters the molding process of Menzin et al. By adding processing steps to securely attach a reinforcing material to the hook fastener strips by extrusion of the J-hook type. U.S. Patent No. 4,984,339 (Provost et al.) Discloses a molded J-shaped hook which has a profile defined by a generally concavely concave inner surface and a generally convex outer surface. The hook tapers slightly and continuously downwards in width from a firm base member to a free end. The hook is designed so that it does not deform when releasing a clip that engages the hook in cut at or below a desired force applied. U.S. Patent No. 5,315,740 (Provost) discloses a molded hook formed as that described in U.S. Patent No. 4,984,339 which is designed to be used with a low profile clip closure system. A displacement volume for the hook is determined which is generally defined as a rectangular parallelepiped surrounding the tip of the hook. There is still a need for an improved method for making hook strips of the J-hook type without the use of complicated and time-consuming molding procedures in order to create J-shaped hooks on a reinforcement material. The invention overcomes the limitations identified above in the field by providing a simple method of making a hook strip having J-shaped hooks which can be used as a mechanical fastener. In a preferred embodiment, the method includes the use of a pre-existing substrate of material formed as a set of straight rods of thermoplastic material on a reinforcement, said rods having tips at the ends opposite the end adhered to the reinforcement. The rod generally narrows from the base to the tip and is preferably symmetrical along its length, for example, circular or polygonal. In addition, a source of adapted heat is provided for heating and also a mechanism for deforming the tips of the rods. The substrate is positioned relative to the heat source so that a portion of the tips of the set of straight rods is heated. Subsequently or simultaneously, the substrate is moved relative to the mechanism to deform portions of the heated tips of the set of straight rods to create a J-shaped hook strip. In addition, an article of manufacture is provided. performed according to the method, which includes a J-shaped hook portion of a hook-loop type mechanical fastener as described below. Following is a brief description of the drawings. Figure 1 is a schematic side view of a strip of J-shaped hooks according to the present invention. Figure 2 is a schematic side view of the straight rods used to form the J-shaped hooks of the invention.

Figure 3 is a perspective view of a portion of a strip of J-shaped hooks according to the present invention. Figure 4 is a schematic view of a method of realization of straight precursor rods and a reinforcement. Figure 5 is a schematic view of a finishing process for forming J-shaped hooks from straight rods on a reinforcement. Fig. 6 is a schematic view of a finishing process for forming multidirectional J-shaped hooks from straight rods on a reinforcement. Fig. 7 is a schematic view of a finishing process for forming multidirectional J-shaped hooks from straight rods on a reinforcement. Fig. 8 is a schematic view of a finishing process for forming multidirectional J-shaped hooks from straight rods on a reinforcement. Figure 9 is an exploratory electron micrograph of a hook according to Example 5 of the invention.

Figure 10 is an exploratory electron micrograph of a hook according to Example 6 of the invention. Figure 11 is an exploratory electron micrograph of a hook according to Example 7 of the invention. Figure 12 is an exploratory electron micrograph of a hook according to Example 31 of the invention. The figures, except for Figures 9 to 12, are idealized and are not necessarily in scale. Figure 1 is a side view of a representation of the hook strip of the present invention 100 for a hook-loop type mechanical fastener which is particularly well suited for use in garments and disposable articles. The hook strips are especially useful in restrainable fastening systems for disposable absorbent articles such as diapers for children, learning panties, adult incontinence articles and feminine hygiene products. The hook strips could also be used in fastening systems on hospital garments and surgical drapes. The hook strip of the invention is formed in a two-step method. The shape of the hook strip after each step is generally shown in Figure 2. The first step is to extrusion molded high straight precursor rods 102, integrally with a film reinforcement 104. The second step is the directional deformation of the rods 102 in J-shaped hooks 106. In a method for carrying out the first step, the rods 102 are made by extrusion molding resins in the cavities formed in a mold in order to form a substrate that has a set of rods straight and an integral reinforcement. In order to facilitate the removal of the rods for the mold cavities, the rods are preferably narrowed from the base to the tip. In order to form a stable base for the hooks and provide a uniform hook head formation, the base is also preferably of a shape that is generally symmetric about its center, such as being polygonal or preferably circular. The rods as such have at least one axis of symmetry and preferably 2 or 3 or more axes of symmetry. A substantially circular shape is preferred in terms of rod stability, resistance to compressibility, manufacturing capacity of the rod and hook head including uniform formation of the hook head. In a preferred embodiment, the rods comprise between approximately 0.1 millimeters (mm) and 5 mm in height. Subsequently, in a preferred procedure for performing the second step, a calender is used in order to form the rods 102 in J-shaped hooks. The intermediate space of the calender is fixed at a height less than the combined height of the rods on the substrate taken with the reinforcement thickness. The calendering roller that deforms a portion of the rods is preferably heated to a temperature that will soften the thermoplastic material forming the rods. The heated calender roll is set to operate at a different speed than the fabric or substrate so that it cleans by rubbing the rod passing through the calandria intermediate space. The action of rubbing on the rods with the heated roller melts and deforms simultaneously the tips that, if properly fixed, they can form the deformed tips in J-shaped hooks as shown in Figure 3, which shows a portion of a hook strip actually formed using the aforementioned calendering method. These J-shaped hooks include a substantially planar upper surface 108. This substantially planar surface 108 may be slightly non-planar throughout its length and width by rising slightly to form a central depression or boiler-like structure. Alternatively, the sides or peripheral region surrounding the substantially flat flat surface 108 may exit forming a slightly rounded elevation or plateau-shaped structure. In any case, the upper portions 108 of the heads of the hooks are generally smooth and flat. It has been unexpectedly discovered that this does not significantly affect the ability of these gaps to show the a-arto, non-woven, woven or relatively knitted fabrics at points while the flat surface 108 provides at advantageously, a non-irritating and soft-touch surface. This flat top surface i or 108 makes the hook strip particularly well suited for use in disposable or seasonal wear applications where mechanical fasteners are used near or close to the skin thereof. Several parameters characterize the shape of the J-shaped hooks 106, as shown in Figures 1-3, which can be produced by calendering or other procedure described herein. These include a high precursor rod 1 10, rod diameter 1 14, final hook height 1 18 and distance between hooks 120. There is also a hook opening width 122, a hook opening height 124, a thickness of 0 hook head 129, hook protrusion 109 as well as the total surface area of the flat upper portions 108 of the hooks all define the hooks. The film gauge or thickness of backing or backing 132 further defines the hook strip of the hook type of the J-shaped gand type. The hook strip 100 can be formed from virtually any thermoplastic material that can be molded by extrusion, as needed. Possible thermoplastic materials include polyolefins, such as polypropylenes, polyethylenes and copolymers as well as mixtures thereof, polyesters, polystyrenes, polyamides and the like. Several alternative methods for forming J-shaped hooks 106 are possible in the second step of the method of the invention. As indicated above, a method includes the passage of a film reinforcement that possesses straight precursor rods 102 through a calandria gap where a heated roller moves at a different speed than the substrate (i.e., either faster or slower than the substrate or even rotating in the opposite direction). Another method includes the passage of the film reinforcement that has straight precursor rods 102 through a stationary heated fastening point so that the forward movement of the film reinforcement causes the deforming movement of rubbing necessary to create the J-shaped hooks. Still another method includes brushing a stationary film reinforcement having straight precursor rods 102 with a rigid heated rotating disk to form J-shaped hooks which are oriented in a circumferential fashion around a central point. An additional method includes forming hooks oriented in more than one direction. This method includes the passage of the film reinforcement which has straight precursor rods 102 through a first grooved calender roll and a second grooved calender roll or second smooth calender roll, where the gaps in the first and second rollers are staggered, if any. that both have gaps. The speed of the two rollers, in relation to the speed of the precursor substrate is, for example, positive (for example, faster) and negative (for example, slower or opposite direction), respectively (to produce hooks that curve substantially "up the tissue" or "down the tissue"). Also, in any of the above-mentioned processes the heating portion of the second step could be carried out independently of the deformation portion of the second step. The heating of the tips of the rods could be carried out by any suitable heat source that includes a type of radiant, parabolic, ultrasonic or focal infrared lamp source which could be used independently or in combination with a heated clamping point . The advantages of the method of the present invention include the ability to manufacture J-shaped hooks 106 which are generally functional as compared to conventional J-shaped hooks in terms of performance, particularly when used in disposable garments and uses. similar, but which can be made more quickly and on a moving fabric or a reinforcement of films wider than what was previously possible with conventional molding and weaving techniques. This is primarily due to the combination of the ease of procedure of the straight precursor rods 102 and the efficiency of the different deformation methods disclosed above. further, the performance of any given hook strip 100 can easily be adapted to a specific loop material by altering the method to change the parameters of the hooks such as the opening height of the hooks, the opening width of the hooks, the final height of the hooks or other structural parameters as will be described and indicated in the examples that will appear later. In order to have good flexibility and strength, the stress of the hook strip 100 is preferably between 0.025 mm and 0.512 mm in thickness and, more preferably, is between 0.064 and 0.254 mm in thickness, especially when the hook strips 100 are made of polypropylene or a copolymer of polypropylene and polyethylene. However, virtually any thermoplastic resin that is suitable for the extrusion molding can be used to produce the novel J-shaped hooks 106 and the hook fastener strips 100. The thermoplastic resins that can be extruded and will be useful in the invention include polyesters such as polyethylene terephthalate, polyamides such as nylon, poly (styrene-acrylonitrile), poly (acrylonitrile-butadiene-styrene), polyolefins such as polypropylene and plasticized polyvinyl chloride. A particular preferred thermoplastic resin is a polyethylene and polyethylene impact copolymer, which contains 17.5% polyethylene, and has a melt flow index of 30, which is available as SRD7-560 through Union Carbide Company, Houston , Texas. For some uses a stiffer thermoplastic material may be used, or the reinforcement 104 may be coated with an optional adhesive layer, such as a pressure sensitive adhesive 138, on its surface opposite the surface provided with the hooks 106, thereby The material could be adhered to a substrate to help secure the hook strip. Other suitable additional reinforcement materials or additional layers include pre-patterned or randomly patterned materials, additional film layers, paper or metal foil. Preferably, when the calendering methods and the like are used, a relative speed differential between the calender rolls is comprised between 0.02 meters per second and 0.5 meters per second. In other embodiments, the heat source is a stationary heated fastening point, a heated disk or a heated roller. As previously considered, various methods for manufacturing straight rods 102 can be used, with Figure 4 revealing an apparatus for carrying out this process step. In Figure 4, a feed stream 144 of thermoplastic resin is fed into an extruder 146 from which a molten heated resin is fed through a die 148 to a rotating cylindrical mold 150. The cavities 158 in the cylindrical surface of the mold 150 are optionally evacuated by an external vacuum system 164. The die 148 has an output radius equal to that of the mold 150 for the purpose of providing a seal between the die 148 and the mold 150. The rapid flow of the resin in the cavities of the mold 158 induces the molecular orientation parallel to the flow direction, and the mold 150 is preferably cooled with water (the cooling mechanism is not shown) to provide rapid cooling in order to maintain this orientation in its place. The solidified resin is separated from the mold 150 by a release roller 168 as a substrate formed as a fabric or film reinforcement 104 having a set of straight precursor rods 102. The film reinforcement 104 can be wound on a roll for storage or fed directly into a J-shaped hook forming apparatus. Once the film reinforcement 104 is produced with straight precursor rods 102, any of the methods described above can be used to form the J-shaped hooks 106, for example, the procedures that can be performed on the apparatus of Figure 5 and considered in detail above. The apparatus shown in Figure 5 includes a crown finishing station with a gap as well as a cooled roll 170 and a heated roller 172. A surface of the film reinforcement 104 is adjacent to and passes over the cooled roll 170 and the portions of the rods 102 are brought into contact with the heated roller 172. The surface of the heated roller 172 is generally movable in the same direction as the film reinforcement 104 travels but at a different speed ranging from faster to slower, which it would include that the roller be completely stopped and, in an extreme condition, that the roller 172 move in the direction opposite to the path of the film reinforcement 104. This speed differential will determine, primarily, the degree of winding or bending imparted to the roller. each rod 102 as the distance between the surfaces of the rollers is reduced.

Figure 6 reveals a deformation method which incorporates an apparatus capable of forming J-shaped hooks 106 from rods 102 of hook orientations in two or more directions and in many combinations of angles with respect to the central line 102 of the film reinforcement 104. This mechanism of the deformation process uses a shuttle mechanism and includes a plurality of guide pulleys 210, 214, 218, and 222, which are fixed to the same structure of the shuttle mechanism. This shuttle mechanism, including the guide pulleys, moves up and down (in the plane of the figure) or with and against the direction of travel of the film reinforcement 104. When the speed of the shuttle mechanism is equated with the line speed of the film reinforcement 104 and moving against d the direction of travel of the film reinforcement 104, then the film reinforcement 104 moves laterally at a speed of up to two times the line speed. When the shuttle mechanism moves with the direction of travel of the film reinforcement 104, then at the appropriate speed of the shuttle mechanism, the film reinforcement 104 can stop the movement laterally. While the film reinforcement 104 has stopped moving laterally, but moves in the original direction of travel to the line speed, it is brought into contact with the first hook forming device 226.

The device 226 is a heated roller with narrow raised rings, evenly spaced 228 on its surface. The surface of these rings can move in the same or in a different direction as the rods relative to the device 226, as previously considered. This speed differential will determine in part the degree of winding or curvature imparted to each contacted precursor rod 102 when the distance between the rings and the film reinforcement approaches its closest point. The hook forming device 226 forms narrow rows 243 of J-shaped hooks 106 as the film reinforcement 104 passes. These hooks 106 can be oriented at an angle of 45 degrees with respect to the center line 202 of the substrate. 104. A second similar hook forming device 250 can make rows 255 of J-shaped hooks 106 oriented at a 45 degree angle from the centerline 202 of the substrate 104 or 90 degrees from the first rows at the same time , when the film reinforcement 104 stops moving laterally. The smooth heated roller 260 subsequently forms any of the remaining straight rods in the regions or rows 264 of J-shaped hooks 106 which are oriented at 135 degrees from any of the other two rows (225 and 243).

When the distance between the rows of rods 102 entering this embodiment of a shuttle mechanism is defined as X, the rings on the first hook forming device 226 are 2X wide and on 6X centers, and the rings on the second hook-forming device 250 are 3X wide and on 6X centers; therefore, an equal number of hooks in the form of J 106 will be oriented in each of the three directions. As those skilled in the art will appreciate, this procedure could be expanded to different orientation angles or more directions of orientation. Still another deformation process for forming J-shaped hooks 106 having more than one direction of orientation is shown in Figure 7 and Figure 8. This device may comprise a stationary heated blade 270 or shoe with teeth centered between each second row of rods 102. Alternatively, as shown in Figure 8, a heated alternative blade 271 can be used. This blade has narrow long teeth which give a bidirectional orientation closer to 180 degrees. In each embodiment, the relative motion deformation principles of the invention operate as described above to create the distinctive hook shapes shown, for example, in Figure 3.

The invention can alternatively be described as a method of making a hook strip having J-shaped hooks which can be used to realize the hook and loop types of mechanical fastening requirements. In a preferred embodiment, the method includes the use of a pre-existing extruded molded integral substrate, such as a film reinforcement, of material formed with a set of straight rods having tips at the ends opposite the reinforcement, the reinforcement and the extrusion molded rods simultaneously. The rods are generally straight projections that taper continuously without any portion of fiber hooking at the tips. Preferably, the pre-existing substrate includes a layer of solidified thermoplastic resin that includes a layer of solidified thermoplastic resin that forms the reinforcement with the same thermoplastic material that also forms the set of straight rods. Also, the preexisting substrate may consist of a single substrate that has a set of straight shoots of differing heights. In addition, a heat source adapted for heating and a mechanism for deforming the tips of the rods are provided. The substrate is positioned relative to a heat source so that a top portion, preferably a distal end portion, including the tips of the rods, of a plurality of straight rods is heated. Subsequently or simultaneously, the substrate is moved to a relative position with respect to the mechanism for deformation so as to create a hook-shaped strip of J-shaped hooks from the heated portion of the set of straight rods. During movement of the substrate, an upper surface is formed, with a substantially flat upper surface. Likewise, the hooking portion of each of the J-shaped hooks is created by the mechanism to deform the heated portion of the set of straight rods. Also, when the substrate is moved, a deformed portion of each of the plurality of J-shaped hooks is oriented asymmetrically relative to a portion of the straight non-deformed stem connected substantially orthogonally to each of the plurality of J-shaped hooks. Alternatively, when the substrate is moved, the heated portion of the set of straight rods on the substrate can be deformed in different orientations as previously considered. This is possible due to the independence of the deformation step with respect to the step or steps necessary to produce the precursor rods. Also those skilled in the art will appreciate that another portion of the set of straight rods on the substrate may be deformed in different ways from the J-shaped hooks during movement of the substrate. Through the method of making the hook strip, a portion of each of the straight rods is not deformed and, preferably, retains an initial molecular orientation. In addition, an article of manufacture is provided, made in accordance with the method detailed above, which includes a hook portion of a mechanical fastener of the hook-loop type. The deformed portion of each set of straight rods may be a generally narrowed distal hook portion which has been deformed so that it extends from a point that projects generally downward (however, in some cases the tip will project down only slightly) to a substantially planar upper portion 108 of the hook portion which is subsequently connected to a straight rod portion. The final average hook height 118 (or deformed stem height) can range between 0.05 mm and 4.0 mm. Likewise, a hook density of the set of heated straight rods can range from 4 rods / cm 2 to approximately 2 rods., 000 shanks / cm2. Preferably, for the purpose of convenience, the article may be rolled into a roll for convenient storage and shipping and subsequently cut into the desired lengths of hook strips 100 as necessary. When rolled on a roll, the substantially flat upper surface 108 of each of the J-shaped hooks on the article is less likely to penetrate any layer of adhesive on the surfaces opposite the hooks compared to the formed front hooks. in different shapes of spikes. The substantially flat upper surface 108 also attenuates the deformation of the film reinforcement 104, due to the distribution of the pressure applied against the individual hooks if the hook strips are wound on a roll or the like. Also, the substantially flat upper surface 108 of each of the J-shaped hooks creates a hook strip that has a tactile feel that is less rough than other kinds of hook-loop type fasteners, for example, more similar to the feeling of a flat film and is much less likely to cause skin abrasions and irritation; Example 1: A roller having a plurality of J-shaped hooks 106, such as those shown in Figure 3, was made according to the conditions of Table I with the dimensions that result from Table II below. In Table I, Relative Speed means the speed of the heated roll relative to the line speed of the substrate (so that, in Table 1, -70% means that the heated roll moves in a direction opposite the substrate to a speed of 14 feet / minute).

Table I Table II The tests used strips of independent hooks 100 of a size of 2.54 centimeters (cm) by 10.16 cm. The tests included a shear strength test using ASTM D-5169 and a 135 degree grip test carried out in the machine direction (DM) (for a better grip of the hooks) and in the transverse direction of the fabric (DT) (for the nominal fastening of the hooks). The adhesion test consisted of a 135 degree peel off of an XML-4069 loop test patch (commercially available through Minnesota Mining &Manufacturing Company) at a peel rate of 30.5 cm per minute. The hook samples were rolled down onto the loop using five passes of a 2.04 kilogram (4.5 lb) roller. The tests were carried out at 70 ° F and 50% relative humidity. The results are shown in Table III.

Table III Examples 2 to 17 In these examples, a device was used as shown in Figure 5 in which the upper heated calender roller 172 was heated with oil; the lower calender roller 170 was cooled with water. Both rollers were chromed and approximately 10 inches in diameter. The lower cooled calender roll was fixed and 3 inch diameter pistons were used to position the heated calender roll. The gap between the heated calender roll and the cooled calender roll was set with a screw and retainer configuration. For the experiments described below, a 40 psi pressure on the pistons was sufficient to prevent the heated roller from floating (opening the gap) when the precursor material was heated. The speed of the heated roller (s2) could be set independently of the speed of the cooled roller (yes). The excess speed is the difference between if and s2. For example, an overspeed of 110% means that the heated roller was rotating 10% faster than the cooled roller; an over-speed of -70% means that the heated roller was spinning back at 70% of the speed of the cooled roller. In all experiments, the line speed of the tissue was dependent on the speed of the cooled roller. Therefore, the surface velocity, U, of the heated roller at the tips of the rods is determined by the formula: ü = if s2 For Examples 2 to 17, summarized in Table IV below, the cooled roll was at 170 ° C (60 ° F) with the clamping pressure set at 276 KPa (40 psi).

The total gauge of the fabric, the thickness of the reinforcement and the height of the rod, was approximately 0.61 mm (0.024 inches).

Table IV For each of the materials of the hook strip formed, the dimensions of the hooks were measured by an optical microscope (an average of 6 measurements). Ax and A2 are lengths and the width respectively of the upper surface of the hook 108. B is the height of the head of the hook 129. C is the projection of the hook 109. D is the thickness of the head of the hook 128 in the base of the head 107 and E is the combined reinforcement thickness 132 and the height of the hook 118. These measurements are set forth in Table V. Table VI summarizes the average release force values for Examples 1 to 16. The values of detachment were measured using ASTM D-5170 (briefly described) against a randomly patterned material (3M XML-5167 available through 3M Company, St. Paul, Minnesota) clip type with the hooks on the strip oriented in the direction transverse to the direction of detachment of the hook strip (which results in generally lower release values). The results shown in Table VI indicate that the height of the hook head has a significant effect on the peel performance with a decrease in head height which generally increases the peel performance. In Examples C4 and C5 the head of the hook was extended and brought into contact with the base film 104 leaving no gap for the fibers to be located under the head and, consequently, zero release values. In Example 2, although there was a small gap (E-B) between the head of the hook and the base film, the head of the hook was very thin at its distal end so that it was relatively easy for the fibers to push it out of the course. On the other hand E-B was related to B so that as it increased (for example, B decreased) the yield of detachment increased in the same way. Generally, when C increased, the adhesion performance also increased. However, the measurement of this value was very inaccurate because it was measured from the top of the hook making the differentiation difficult and, even though the measured value was zero, a projection was still probable from the tip of the head of the hook. Deformed hook.

Table V Table VI 15 Examples 18 to 33: For Examples 18 to 33 the gap width was modified to 0.5 mm (0.019 inches). On the other hand, the examples were carried out in the eqent described for Examples 2 to 17 with the conditions established in these Examples and in Table VII below.

Table VII The dimensions of the hook materials of Examples 18 to 33 were subsequently measured as were those of Examples 2 to 17 and as set forth in Table VIII. The reported measured values were the average of six different hooks.

Table VIII These Examples were subsequently tested for release performance as well as Examples 18 to 33. The same trends were observed.

Table IX 15 It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (28)

1. CLAIMS Having described the invention as above, the content of the following claims is claias property: 1. A method for continuously forming a hook strip having a plurality of J-shaped hooks that can be used as a mechanical fastener, the method is characterized in that it uses a substrate of initial material, the method comprises the steps of: a) providing a substrate of thermoplastic material having a softening temperature comprising a support having an array of vertical reforprecursor rods of the thermoplastic material having a softening temperature and having vertical distal tips at the ends of the rods opposite the support, tips distal which have first dimensions in cross section; b) providing a heat source adapted to heat a plurality of rod tips to a temperature above the softening temperature; c) providing a mechanism for deforming a plurality of distal rod tips; d) placing the substrate in contact with the heat source so that the distal tip portions of a plurality of vertical rods are preferentially heated above the softening temperature; and e) moving the substrate in contact with the deforming mechanism in order to create a strip of hooks having a plurality of J-shaped hooks created by contacting the softened and heated distal tips portions of the array of vertical rods on the substrate with the mechanism for deformation, and in this way form defordistal tip portions with generally flat upper surface portions on the defordistal tip portions of the rods wherein the defordistal tip portions have different second cross-sectional dimensions to the first cross-sectional dimensions of the non-defordistal tip portions of the rods. The method of claim 1, characterized in that the movement step includes forming a substantially uniform and flat top surface portion on the defordistal tip portions of each of the plurality of J-shaped hooks. 3. The method according to claim 2, characterized in that the movement step further includes asymmetrically orienting the defordistal tip portions of each of the plurality of J-shaped hooks in relation to substantially undeforportions of the precursor rods of each of the plurality of J-shaped hooks. The method according to claim 3, characterized in that the contact with the deformation mechanism generates defordistal tip portions that are partially orthogonally oriented relative to the non-deforportions. The method according to claim 1, characterized in that the step of providing the heat source comprises providing a heated calendered roll. The method according to claim 5, characterized in that the placement step includes placing the substrate on another calendered roller. The method according to claim 6, characterized in that the calendered roll on which the substrate is placed is a cooled calendered roll. The method according to claim 6, characterized in that the calendered roll on which the substrate is placed is adjacent to the heated calendered roll and is rotated at a speed different from that of the heated calendered roll. The method according to claim 8, characterized in that the relative speed differential between the two calendering rolls is between 0.5 meters per second and 0.02 meters per second. The method according to claim 6, characterized in that the calendering roll on which the substrate is placed is adjacent to the heated calendered roll and is rotated in a different direction as compared to the heated calendered roll. 11. The method according to the claim I, characterized in that the step of providing a heat source comprises providing a heat source which is selected from the group consisting. of a stationary heated nip, a heated disk, a heated roller, a radiant heat source, a parabolic heat source, an ultrasonic heat source and a focused infrared heat source. 12. The method in accordance with the claim II, characterized in that the placement step includes heating a disk-shaped heat source which contacts the substrate in a manner in a relative circular motion to form a plurality of J-shaped hooks having a circular forming pattern in a plan view The method according to claim 1, characterized in that the movement step includes deforming the heated distal tip portions of the array of vertical rods on the substrate in different orientations. The method according to claim 13, characterized in that the step of providing the heat source includes providing a heated disk having a deformed surface with a circumferential ridge pattern. 15. The method according to claim 1, characterized in that the initial substrate is a single substrate having an array of vertical rods of different heights. The method according to claim 1, characterized in that the step of providing the heat source includes providing a plurality of heated grooved calendered rollers adapted to deform a portion of the array of vertical rods on the initial substrate, in different orientations. The method according to claim 1, characterized in that the movement step includes moving the substrate so that a center line of the substrate is not orthogonal with a center line of the mechanism for deforming the distal tip portions heated in arrangement of rods vertical The method according to claim 1, characterized in that the movement step includes deforming a portion of the array of vertical rods in different shapes than the J-shaped hooks. 19. A hook strip article for use as a fastener mechanical, the hook strip is characterized in that it has a plurality of J-shaped hooks that can be used as a mechanical fastener, the hook strip is made by using an initial substrate of a solidified thermoplastic resin formed as a film backing and an arrangement of vertical precursor rods having a first cross-sectional shape, formed of the same solidified thermoplastic resin having distal tips at opposite ends to the film support, the film support and the precursor rods are extruded simultaneously, each hook in shape of J formed from a distal tip of a vertical precursor rod, J-shaped hooks which have a second cross-sectional shape different from the non-deformed portion of the first cross-sectional shape of the precursor rod and having a substantially planar upper surface formed on a deformed, asymmetrically oriented portion. 20. The article of claim 19, characterized in that the initial substrate comprises an integral substrate that forms the support and arrangement of the substantially symmetrical vertical rods. 21. The article of claim 19, characterized in that the initial substrate comprises the support and the arrangement of the vertical rods and the symmetrical rods have more than two axes of symmetry. 22. The article of claim 19, further comprising an additional material connected to the initial substrate support. 23. The article of claim 19, characterized in that the deformed portion of each of the heated vertical rods comprises a distal tip projecting downwardly. 24. The article of claim 19, characterized in that the final height of the hook of the deformed rods of the arrangement of the heated vertical rods varies between 0.05 millimeters and 4.0 millimeters. 25. The article of claim 19, characterized in that the density of hooks of the deformed rods of the array of heated vertical precursor rods varies between 4 rod per cm 2 and 2,000 rod per cm 2. 26. The article of claim 19, characterized in that the hook strip holder further includes an adhesive layer, which is substantially continuous and which is wound onto a roller for convenient storage and transport. 27. The article of claim 19, characterized in that the arrangement of vertical rods is configured such that two different portions of the substrate can be interengaged to provide a mechanical fastener. 28. The article of claim 19, characterized in that the article comprises a structure that is selected from the group of structures that include fasteners for garments, resilient fastening systems for disposable absorbent articles, fastening systems for surgical cures and bonding systems for abrasive articles.