HK1023701A - Molding of fastening hooks and other devices - Google Patents

Description

Molding of hook and other components of fastener

no marking

Background

The present invention relates to a molding method, a molding apparatus, and a molded product, and to the manufacture of molded articles, particularly hook-type fasteners for engaging loops.

In the field of molded hook-type fasteners, it is common for a series of adjacent rows of hooks to form one or component of the fastener closure, with the other component used in cooperation to provide loops or anchoring fibers for engagement by the hooks.

Fastener elements with rows of hooks are typically made using mold tools without moving parts. The hooks are pulled out of their cavities by twisting the hooks. A rotary mold roll is used to mold the continuous hook strip of hooks, while injection molding techniques are used to mold the individual pieces. Improvements in these molds and molding processes may also be useful for molding other products. Summary of The Invention

An important aspect of the present invention relates to a method of molding a plurality of components, particularly a method of molding a fastener, and more particularly, to a method of molding hooks of a touch fastener protruding from the same base using a plurality of mold plates mounted face to face, the method comprising the steps of: forming cavities in the plurality of mold plates in the shape of the assembly; assembling the mold plates together face-to-face to provide a mold surface, the sides of some of the mold plates covering the cavities in the sides of others of the mold plates; placing the mold surface against the other surface and forming a gap G therebetween; filling a volume between the mold surface and the oppositely disposed surface with molten resin; and after the resin is cured, removing the molded assembly and the substrate integral therewith from the mold surface.

According to an important aspect of the invention, the cavities are made using a photo-chemical technique, a mask is used on the side of the template, the shape of the mask being similar to but different from the desired shape of the component or part of the component to be molded, to correct for the non-uniformity of the predetermined etching process, and the metal of the template exposed by the mask definition is etched using the predetermined etching process to provide the desired cavities.

According to another aspect of the invention, multiple templates are etched using respective masks to form individual components or snap-together, and the templates are assembled in sequence with one another; preferably, at least some of the plurality of forms are laminated together to form a thicker form assembly.

According to another feature, at least two of the die plates have mating cavity portions which together define a relatively sharp point on a portion of the hook for engaging a loop or fiber of a mating member for a hook and loop fastener.

Preferably, in some cases, the cusps are formed at the hook tips at a first location where the hooks contact the loops or fibers of the loop element, the hook elements being movable face-to-face against the loops; in other cases, the sharp point is located at the distal tip of the hook portion of the hook to engage and guide the loop into the loop-capturing region of the hook.

In the latter case, the distal portion of the hook is preferably located in a region where the angle α is less than 30 °. In certain preferred aspects, the molding process is adapted to produce a tip that tapers to a relatively sharp point in end and side views.

In accordance with yet another aspect of the invention, the cavity forms a hook component of a hook and loop fastener, the hook component having a hook terminating in a distal tip, one or more edges of the mask defining the distal tip being oversized and one or more edges of the mask defining the concave curved surface being undersized. The inner surface of the hook is concave and encloses a loop-trapping region, one or more edges of the mask defining the concave curve are reduced in size, while the upper edge of the hook is convex and one or more edges of the mask defining the convex edge are increased in size.

In accordance with another aspect of the invention, the hook member has a hook portion terminating in a distal tip, the tip being directed toward the base, the hook having a concave inner surface defining an apex located closer to the stem or base of the hook than to the tip.

In accordance with another aspect of the invention, the mask defines a hook, and (a) in the x-y profile, a distal portion of the hook is substantially tapered to form an included angle of less than about 30 ℃, (b) in the distal portion, a central axis of the hook is directed substantially downward toward the base, (c) a radius of curvature of a concave inner surface of the hook decreases from the distal end along the curved surface toward the apex, and (d) the apex of the loop-trapping region is located laterally closer to the stem or base than to the distal end of the hook.

In accordance with a further important aspect of the present invention, the cavity defines a hook component of a hook and loop fastener, (a) the edge surface of the die plate directed toward the gap is configured to provide a maximum accuracy of ± 0.001 inch between portions of the die plate at the edge of the die plate, and (b) the thickness of the gap (t) is_b) Is less thanAbout 0.003 inch and, in some preferred cases, less than about 0.002 inch, thereby providing an ultra-thin molded fastener strip.

In accordance with a further important aspect of the invention, the die plate is formed from a hardened copper alloy, preferably beryllium copper, preferably containing 1.9% by weight beryllium.

According to another aspect of the invention, the hooks of the hooks extend in a direction at an angle to the plane of the die plates, the shape of the hooks being defined by the cut-outs of the die plates.

Another feature of the invention is a mold in which a given mold plate is formed with cavity portions in each side thereof, the cavity portions being stacked in offset relation to each other with the sum of the cavity depths that penetrate the depth of the mold plate being greater than the thickness of the mold plate (see fig. 25). The pockets define at least a hook portion of the hook and loop fastener, and the effective overlap of the pockets provides a high density of hooks in the hook component.

According to another aspect of the invention, molten resin is fed into such a mold from an extruder. In certain preferred aspects, the die plate forms a mold roll and a pressure roller forms a nip with the mold roll where the extruded plastic forms a molten plastic melt. In another case, molten resin is supplied under pressure from an extruder against a mold roll with a nozzle. In each case, it is preferred to cool the copper base alloy template with a circulating cooling fluid passing through the template.

Another feature is a mold wherein a given mold plate is formed with cavity portions in each side thereof, the cavity portions being offset from one another and stacked one above the other, the sum of the cavity depths penetrating the mold plate being greater than the thickness of the mold plate. In making hook members for hook and loop fasteners, the effective overlap of the mold cavities results in a high density of hook elements in the hook component.

According to another aspect of the invention, molten resin is fed from an extruder into the mold so made. In certain preferred embodiments, the die plate forms a mold roll, a pressure roller forms a nip with the mold roll, and the extruded plastic forms a bank of molten plastic at the nip. In another case, molten resin is dispensed from an extruder under pressure against a mold roll by a nozzle. In each case, it is preferable to cool the template made of the copper-based alloy by circulating a cooling liquid through the template.

Another aspect of the invention features a mold having a surface that is treated with a chemical etchant to provide a surface having a surface roughness of less than about 75 microinches, preferably less than about 60 microinches. In a preferred embodiment of this aspect, the cavities are made by a photochemical technique that produces a finished surface that produces a side surface on each die plate with a dimensional tolerance of less than about 0.001 inch, and in many cases, less than about 0.0005 inch. In some preferred embodiments, after the cavities are formed using a photochemical etching technique, the mold plates are assembled face-to-face and machined to the desired dimensional tolerances, and the assembled mold plates are etched to remove burrs that extend into the cavities. In other cases, other techniques are used to pre-form the cavities of the mold plates, then the mold plates are assembled together face-to-face and machined to the desired dimensional tolerances, after which the assembled mold plates are etched to remove the burrs that extend into the cavities. In these cases, the template is preferably made of copper beryllium and the work-hardened burrs are preferably removed by an etchant.

In a further aspect of the invention, a molding apparatus for making ultra thin hook components and their products itself, the apparatus comprising a series of mold plates mounted face to form a series of cavities in the sides thereof, the cavities being shaped to form hook members, and an opposed mold member, the edges of the mold plates and the surface of the opposed mold member defining a molding gap (G) in which a base layer integral with the hook members is formed when the cavities and the gap between the edges of the mold plates and the opposed mold surface are filled with an injection moldable resin, the apparatus being characterized in that (a) the edge surfaces of the mold plates directed toward said gap are made with an average of the positional accuracy of the mold plates relative to the edges of the mold plates of at most 0.001 inch from the mold plates to the edges of the mold plates, and (b) between (b) the base layer is madeGap thickness t_bLess than 0.003 inch, thereby forming an ultra-thin molded fastener strip. In a preferred embodiment of this aspect, the positional accuracy is up to 0.0005 inches and the die plate is made of a hardened copper alloy, preferably copper beryllium. In certain embodiments, the beryllium copper alloy contains about 1.9% by weight beryllium. In the preferred embodiment of the product of the invention, the die plates are circular and are stacked to form a cylindrical mold roll, and the molten plastic is applied to the mold roll against the placed parts; the opposed members are formed by forming a nip with a mold roll through which molten plastic enters the mold roll, the nip (G) between the mold roll and the pressure applying roll being less than about 0.003 inches and determining the thickness (t) of the fastener substrate_b). In other embodiments, the opposed component is an extruder nozzle face (480) which abuts the mold roll to form a gap (G) with the mold roll of less than about 0.003 inches which determines the thickness (tb) of the fastener substrate. In other embodiments, the opposing components and the mold plate together comprise an injection mold associated with an extruder.

In any of the above embodiments, the surface forming the fastener cavity has a roughness of less than about 75 microinches, and in many cases less than about 60 microinches.

Preferably, the cavity and edge surfaces of the template are formed by one of the techniques mentioned above, namely, photochemical techniques with special mask modifications or other techniques, including metal machining followed by a slight chemical etch to effectively remove burrs from the cavity without damaging the major shape features of the cavity.

Another important aspect of the present invention is a hook component for overlapping an adhesive loop element, the hook component comprising a base and a plurality of hooks engageable with loops, the hooks being integrally molded with the base, characterized in that the base is made of a plastic resin and has a thickness (t) of_b) Less than about 0.003 inches, and preferably less than about 0.002 inches. In the preferred embodiment, the hook component is molded from a thermoplastic material.

As mentioned above, an important type of touch fastener is characterized in that (a) in the extending direction of the hook, the hook portion is substantially tapered to form an angle (α) of less than 30 °_x，y) (b) the central axis of the hook portion is generally, in some embodiments, directed downward, toward the fundus at the hook tip, (c) the radius of curvature of the inner surface of the hook portion decreases from tip to apex, and (d) the apex of the loop-trapping region is located laterally closer to the stem or base than to the tip of the hook portion.

The apex of the ring capture zone is spaced a distance (delta) from the distal end of the hook portion₁) The distance (delta)₁) Greater than the transverse distance (delta) from the outermost end of the hook to the rod or base₂) Two-thirds, preferably more than three-fourths, of the total weight of the composition.

The thickness of the hook tapers out of the plane of the direction in which the hook extends (fig. 21), tapering towards the tip of the hook portion. Preferably, the transverse profile of the distal portion of the hook is generally tapered to form an included angle (α) of less than about 30 °_z1) And the tip portion is directed substantially downwardly toward the base.

In some embodiments, the hook portion has one straight side and one convex side in the transverse profile, and in other embodiments, the hook portion has two opposite convex sides. In each case, the convex surface is curved in the following manner: the cross-section perpendicular to the central axis is relatively thick at that axis, tapering toward the upper and lower surfaces of the hook.

In the vicinity of the tip, the inner surface of the hook portion forms an angle (psi) with a perpendicular to the base₁) At the same time, from the tip to the apex, the inner surface of the crook portion forms a total angle of inclination (Ψ) with a perpendicular to the base.

In these embodiments, the cross-sectional area of the hook portion increases substantially linearly as a function of distance from the tip along the central axis in a plane perpendicular to the central axis of the hook portion, and the upper surface of the hook portion is generally wedge-shaped. In some embodiments, the wedge is formed by the intersection of one flat side of the hook portion and one convex side projecting to the other side, while in other embodiments the wedge is formed by the intersection of two convex sides of the hook portion projecting in opposite directions.

Also in the preferred form, the inner surfaces of the crook portions are substantially elliptical, the major axis of the ellipse forming an angle with the normal to the base of greater than 10 ° and less than 30 °.

In many cases, the molded feature is that it has a shape that allows it to be molded in a stationary mold and that allows the hook to be removed from the cavity by pulling it without opening or removing the mold parts.

Other aspects of the invention relate to the realization that a hook component of a molded fastener with small sized hooks (e.g., less than about 0.025 inch in height) can provide better engagement with low loops or fibers of inexpensive fabrics because of the increased likelihood that each hook of the fastener will engage a loop or fiber.

There are many seemingly contradictory insights into the manner in which the present invention achieves the goal of providing an efficient snap engagement. As the hook elements become smaller and thinner, they become softer. This increases the tendency of the hooks to disengage from the mating fibers under a slight force. To better catch and hold the loops or fibers on the mating fabric, it is often important that the small hook elements have a substantial secondary entry hook, i.e., a downwardly sloping hook tip. It is also important that the replacement volume of the hooks of the hook elements be small so as to be able to penetrate sufficiently into the low, soft fabric to be bonded to the loops or fibers. It is desirable that the replacement volume of the hook is less than 1.0X 10 as follows^-6Inch (L)³Preferably about 0.5X 10^-6Inch (L)³Or smaller. Of course, it is also important that the tensile and shear strength of the overall fastener meet the strength requirements of the application. Thus, the hooks and loops must be strong enough to maintain engagement, yet flexible enough to disengage without damaging the hooks or loops.

The preferred known technique for making high performance hooks is to use a mold without moving parts, but it is particularly difficult to produce hooks of the dimensions referred to herein using this conventional technique.

The present invention provides improved molds and techniques for producing hooks and other products, improved techniques for making molds, and improved products.

In accordance with one aspect of the present invention, by using special shape parameters in the hook forming cavities, efficient molded hook elements having efficient loop or fiber hooks with hook replacement volumes of less than 1.0 x 10 inches can be conveniently produced at high speed and low cost with a height of less than 0.020 inches^-6Inch (L)³Preferably about 0.5X 10^-6Inch (L)³Or smaller (herein, such hooks are sometimes referred to as micro-hooks).

The hook shape formed by a conventional cavity consists of a shorter base, an elongated stem portion and a hook or return portion. We have appreciated that effective miniature hooks can be produced by using such a cavity profile which is substantially defined by a base portion to which a tapered hook portion is directly attached.

In a preferred microhook-type cavity, the width and taper of the base is also important. Preferably, the base is at least about 100%, and more preferably at least about 110% or more of the total hook height. The taper (ratio of width to distance along the hook axis) of the hook cavity from the base to at least the half height of the hook cavity is preferably greater than 0.6: 1, more preferably greater than 0.8: 1, and most preferably greater than 1.2: 1.0.

In this preferred profile, the base cavity tapers more from the base to the middle of the hook than the hook sections. A base taper of more than 4 times, preferably more than 5 times, the hook taper is used. In a preferred embodiment, the sides of the cavity contour are straight sides, and the sides of said tuck-in are extended to meet to form a vertex angle which is equal to or greater than 40 °, preferably at least 50 °, and in this preferred embodiment 60 °.

A mold of this construction produces hooks that are strong in terms of their size, yet achieve a high hook density.

This mold structure also allows the hook portion of the molded hook to quickly reach an expanded region after undergoing deformation during withdrawal from the fixed mold cavity, providing room for the hook to return to its original molded shape.

By using these novel cavity parameters, some of the conditions in microhook molding can be overcome. The hooks have a memory of their original molded condition immediately after molding in a cooling mold. After deformation, the hooks tend to return to their original shape. However, if the hook is bent too much, it cannot be pulled out of a fixed cavity unless the hook is still warm and easily deformed. The hook cools to some extent during pull-out and tends to retain its deformed shape without substantially returning to the designed hook shape.

These factors have been found in the molding of large hook pieces, but have not been very important. However, these factors are known to be even more important for miniature hooks because the very small hook tip has a significantly increased exposed cooling surface ratio relative to mass, and the fiber engaging hooks are easier to cool and more quickly shape than conventional large molded hooks. With the novel cavity parameters provided by the present invention, the extent to which the hook is secured in the deformed state is reduced because the time for which the hook element is in the deformed state is reduced. This allows the production of miniature hooks with high performance. It is also known that products produced using the above described mold cavity profiles and techniques have other advantages even where rapid recovery of the hook tip shape is not important. The wide base to which the hook is directly attached provides a profile with high strength under shear forces. Thus, the thickness of the hooks in cross-section along the row of hooks can be as much as 0.008 inches or more less than conventional thicknesses; preferably, the hooks have a thickness of 0.006 inch or less. Also, the spacing between adjacent rows of hooks can be less than 0.010 inch, and preferably about 0.008 inch or less. The distribution density of the hooks in the direction intersecting the row direction of the hooks can be up to 50 hooks per inch or more, and preferably about 70 hooks per inch or more.

The reduction in hook size also provides a distribution density of hooks in the direction of the row of hooks of up to about 20 hooks per inch or more, and preferably about 25 hooks per inch or more.

Specifically, the molded area density is greater than 1000 hooks/inch²(preferably greater than 1500 hooks/inch)²) Is possible. The area density and structure of the hooks provides an integrated strength effect that meets the strength requirements of many applications, while providing a gentle hook surface by virtue of the surface effect provided by the closely adjacent hooks. A moderately downwardly oriented tip enhances this effect. This feature makes the hook useful when used on items placed against the skin.

The inventive die profile is particularly effective in producing a continuous length of product having a plurality of high performance closely spaced rows of hooks when the die is disposed on a rotating mold roll. The present invention is also useful for a stent used in injection molding. By using photochemical milling techniques, which have unique advantages for making molds for micro-hooks, micro-hook molds can be efficiently produced. They are capable of producing extremely small (less than 0.010 inch in height) hooks, which are very small and we call "mini hooks". Moreover, these techniques provide the mold cavity with an extremely smooth surface. These cavities have particular utility in the production of hooks for use with very low top layer materials. In some cases, laser machining, Electrical Discharge Machining (EDM), and coating techniques may also be used to make molds for use on the unique products of the present invention.

The fastener of the invention can also be suitably oriented at different angles to the machine direction of the mold roll or mold formed from mold plates assembled face-to-face to form the cavities by aligning the cuts or cut holes in a plurality of adjacent mold plates.

According to one aspect of the present invention, a mold is provided for integrally forming a plurality of hook members on a plate-like or tape-like substrate from a moldable resin. The mold has hook-shaped cavities in the mold surface, at least a plurality of the hook-shaped cavities having adjacent one tapered base cavity and one crook cavity.

In a preferred embodiment, the base cavity has a base width greater than the approximate height of the hook shaped cavity and a width at half height of the hook shaped cavity equal to about half the height of the hook shaped cavity or greater.

An important aspect of the invention is that the lower portion of the base cavity is much wider than the hook cavity, thus providing space for the molded hook member to substantially return to the shape of the cavity before it is completely removed from the cavity.

In particular embodiments, at least a plurality of the hook shaped cavities have a height of less than about 0.015 inch, and preferably less than about 0.010 inch.

In some embodiments, at the point of molding, the mold operates with an extruder in the vicinity of the cavity to supply molten resin to the cavity.

In some cases, means are provided for applying pressure to the molten resin in order to facilitate filling of the cavity. In some instances where the mold is a mold roll, the means for applying pressure is a pressure applying roll. In other examples where the mold is a mold roll, the pressure applicator is a nozzle face that is mounted against the mold roll to confine the molten resin under pressure.

In some embodiments, at least some adjacent templates are laminated together.

Preferably, the hook shaped cavities are of the photochemically machined type.

In some important embodiments, the hook cavities of the hook cavities are disposed at an angle to the die plate. In other embodiments, the hook cavities are perpendicular to the die plate.

For some applications, the hook shaped cavities are placed in an inclined pattern around the mold roll.

In accordance with another aspect of the invention, molded hook and loop fastener elements of hook-and-loop touch fasteners are made by feeding a moldable, heated material into a mold in accordance with the above-described method.

In some embodiments, the molded hook and loop fastener elements are molded in a single hook cavity formed by arranging cutouts in at least three adjacent mold plates. Preferably, the cavities are formed by actinically milling the die plate.

Preferably, the molded hook elements have a height of less than 0.020 inch and a thickness of about 0.006 inch or less, and the hook elements are arranged on a substrate at a density of at least 1200 molded hook elements per square inch.

In some preferred embodiments, the molded hook has a displacement volume of less than about 0.5 x 10^-6Inch (L)³. Brief Description of Drawings

FIGS. 1 and 1A are side views of a mold cavity;

FIGS. 2 and 3 are side and top views, respectively, of a hook component;

FIGS. 2A, 2B, 2C, 2D are side, end, top and perspective views, respectively, of a hook element;

FIG. 4 is a schematic view of a system for forming hooks using a pattern roll and a pressure roll; FIG. 4D is a schematic view of a system for forming hooks using profile rolls and an extrusion head;

FIG. 4A is a perspective view of a mold roll positioned alone; FIG. 4B is an enlarged view of a portion of the surface of the profile roll; FIG. 4C is a perspective view of a mold showing schematically the orientation of the mold cavity;

FIGS. 5A and 5B are a series of side views showing the removal of hook elements from the cavities of the mold roll in and against the machine direction, respectively;

FIG. 6 is a partial cross-sectional view of a mold cavity formed by several adjacent mold plates;

FIGS. 7A-7K are cross-sectional side views schematically illustrating the template of FIG. 6;

FIGS. 8A and 8B schematically illustrate cross-sectional side views of the die plate of FIG. 6, wherein the cut-out is curved and forms a wedge at the top of the die cavity;

FIGS. 9A and 9B are side and end views, respectively, of one hook member forming a wedge at its top;

FIG. 10A is a side view of a hook member having a curved edge; FIGS. 10B and 10C are cross-sectional views of the hook element shown in FIG. 10A;

FIGS. 11A and 11B show perspective views of a portion of the surface of a mold roll with mold cavities having different orientations relative to the machine direction;

FIG. 12 is an end view of the hook member having a taper at 90 degrees to the direction of formation;

FIG. 13 is a perspective view of a hook member having a circular cross-sectional shape; FIGS. 13A and 13B are cross-sectional views of the hook element shown in FIG. 13;

FIG. 14 is a plan view of a mold cavity for making the hook element of FIG. 13;

FIGS. 15 and 16 are schematic views of a cavity and a mask for making the cavity by photochemical etching; FIG. 15A is a cross-sectional view of a cavity formed by photochemical etching;

FIG. 17A is a side view of a small hook; FIG. 17B is a side view of a miniature hook; FIG. 17C is a side view of a miniature hook with a hook portion extending substantially horizontally;

FIG. 18 is a front elevational view of a double hook in accordance with the present invention;

FIGS. 19 and 19A are enlarged fragmentary views with the distal portion of the hook of FIG. 18 broken away;

FIG. 20 is a cross-sectional view of the hook of FIG. 21 taken along line 20-20 of FIG. 18;

FIG. 20A is a cross-sectional view of the hook of FIG. 21A taken along line 20-20 of FIG. 18;

FIGS. 21, 21A and 21B are side elevational views of the first, second and third embodiments, respectively, of the hook of FIG. 18;

FIG. 22 is a front elevation view of a cross-shaped double hook;

FIG. 23 is a top view of the hook shown in FIG. 22;

FIGS. 23A, 23B and 23C are top views of other cross-hooks having one hook portion, three hook portions and four hook portions, respectively;

FIG. 24 is an enlarged partial cross-sectional view taken between a region through a series of die plates and an oppositely disposed component;

fig. 25 is an enlarged view of the mold surface with a different shape of stacked cavities. Detailed description of the preferred embodiments

Referring to fig. 1 and 1A, there is shown the profile of a mould cavity 1 according to a preferred embodiment of the invention. The cavity 1 is formed by a base or cavity P and a crook portion or cavity C. The shape of the base is a triangle with wide bottom, the straight edges of the base are prolonged, and the base is intersected into a vertex angle alpha at a position close to the top of the cavity. The total height of the cavity is H, and the half height is H/2.

The base width of the cavity profile is B_wMeasured between the intersection points of the mold base 110 and the extensions 117 and 118 of the sides of the cavity. Its value is greater than the hook height H. In the figure, B_wAbout 1.1 times the height of the hook. At half height (H/2) of the cavity, width W of the susceptor_pApproximately equal to half the height of the hook.

The apex angle α is about 60 °, and the susceptor tapers continuously from its base (excluding the front and rear fillets 121 and 122) to a point above half-height in a taper of about 1.2. Thereafter, the inner surface 217 of the cavity begins to curve to form the lower surface of the crook portion, while the rear surface 218 of the cavity contour continues to extend linearly a distance. The base is considered to be finished when a tangent T to the inner surface 217 is a vertical line. Referring to FIG. 1A, the base height H_pGreater than half the height of the hook.

The hook portion of the cavity tapers continuously to its tip, but at a much smaller magnitude than the base. In the profile shown in fig. 1A, the hook portion continues to decrease until its tip reaches down to the plane of the base tip.

Figures 2, 2A, 2B, 2C, 2D and 3 illustrate a hook component 100 of a touch fastener in accordance with a preferred embodiment of the present invention. The hook component is comprised of a base 10 and a plurality of parallel rows of integrally molded hook elements extending from the base. Depending on the application, the hook elements may be aligned or offset to use rip-stops (not shown), i.e., known localized raised areas of the base in the spaces between rows of hooks.

The same terminology will be used below to describe the features of the hook elements made from the mold cavities. The broad-sided tapered base 13 of the hook element is integrally formed with the base 10 and projects upwardly from the base 10. The outer shape of the base is a straight-sided cone when viewed from the side (see fig. 2). The tapered hook portion 14 is integrally formed with the base. The hook portion arches from the base top along a bending axis 15 toward a tip 16. The tip is adapted to engage a mating fabric.

The width of the hook portion (dimension D in fig. 2A) measured perpendicular to its bending axis decreases gradually from the base to the tip.

The front and rear surfaces 17, 18 of the susceptor form theta with the sheet form base, respectively₁Angle theta₂Angles, both of which are greater than 90 °. Preferably, theta₁、θ₂Between 110 ° and 130 °. Preferably, θ₁、θ₂Approximately 116 deg. and 125 deg., respectively. Preferably, the leading and trailing edges of the hook profile, when extended, intersect at an included angle α of at least about 40 °, preferably about 50 °, and most preferably about 60 ° or greater. The angle between the axis 15 and the base is preferably greater than 80 deg., and preferably about 90 deg.. The base is a truncated wide-bottomed cone when viewed from the side, the sides of which are inclined inwardly towards each other, so that the hook can be removed from the mould cavity 1 more easily because the hook portion 14 can pass more easily through the base-forming part of the mould cavity, i.e. through the base cavity. In addition, because the base width is large, each hook element can withstand relatively high shear forces despite the thin thickness of the hook element, which can result in a high hook crossing density. Moreover, the wider base allows the hook to have a higher resistance to bending, thereby allowing it to grip onto the loop more firmly.

The hooks are typically small when used in certain critical applications with nonwoven loop elements (which may be as little as 0.001 inch in diameter and as little as 0.0005 to 0.0020 inch in height). The height 130 of the hooks 12 is preferably less than about 0.020 inches, and for small hooks, preferably less than 0.0150 inches. Further, for hooks having a height of about 0.015, the base width 19 (i.e., the width of the base at a plane parallel to the base 10 where the base and base are joined together regardless of the rounded corners 21 and 22) is preferably between about 0.010 inches and about 0.025 inches, and more preferably about 0.0170 inches.

Referring to fig. 2D, the replacement volume of the hook elements is defined by a parallelepiped 110 having a bottom surface 101, first and second side surfaces 102, first and second end surfaces 103, 104 and a top surface 106. The base surface is oriented parallel to the base and tangential to the tip. The top surface is parallel to the base and tangent to the top of the hook element at the point where the hook element is at a maximum distance from the base. The side faces lie in the plane of the hook side. The first end surface 104 is perpendicular to the bottom surface at the point where the bottom surface meets the hook element at its trailing edge 18. The second end surface 103 is perpendicular to the bottom surface and tangent to the outermost end of the hook portion. The height of the hook part of the cavity is H_cWidth of W_cAnd the thickness is t. The displacement volume DV of the hook portion of the hook element molded in the mold cavity can be calculated by the following formula: DV ═ W_c×H_cX t. Replacement volume of hook less than 1.0 x 10^-6Inch (L)³Preferably less than or equal to 0.5X 10^-6Inch (L)³。

Referring to fig. 1A, the protruding amount of the hook portion, i.e., the distance W by which the hook portion extends laterally from the tip end of the base₁Greater than 40% of the width of the hook portion.

The profile also satisfies the optimum constraint that the susceptor be at its width W_pEqual to the width W of the hook part_cAt a position of height P₁Greater than the base height H_p30% of the total.

The outer contour may be implemented in many preferred embodiments to provide a height of less than 0.020 inches and a displacement volume of less than 0.5 x 10^-6Inch (L)³The small hook of (1). In one particular embodiment, a hook element having an overall height H of 0.015 inch is provided. Width W of hook_cIs 0.013 inch, height H_c0.005 inch, thickness t 0.006 inch, displacement volume 0.4X 10^-6Inch (L)³。

The fastener 100 or hook strip including the hook elements is preferably made using the Fischer process disclosed in U.S. patent No. 4,794,028, incorporated herein by reference, in which rows of hooks are formed around respective disc-shaped forms that are interfolded with divider forms that form the flat sides of the hook elements, forming mound-like reinforcement portions in the divider forms that enhance the strength of the hook strip. In a preferred embodiment shown in fig. 3, there are preferably 24 hook elements per inch in the machine direction (i.e., the direction in which the formed belt moves). The hooks are preferably spaced apart laterally (i.e., in the cross-machine direction) by a distance 23 of about 0.008 inches, and the thickness 24 of the base 13 is preferably about 0.006 inches. Thus, a density of about 71 fasteners per inch in the cross machine direction can be achieved. Thus, there are about 1700 hook elements per square inch.

As shown in fig. 4, a preferred method of making such molded hooks entails extruding molten resin into a nip formed between a chill roll 80 and a pressure roller 82. The chill roll has a cavity 1 at its periphery configured to make a hook and cooling channels 83 along its length for circulating a liquid coolant. A woven or non-woven fabric backing 201 may be fed to the nip from a backing roll 200. The straps may be provided with loops adapted to engage the hooks. The fastener thus produced will include hooks adhered to the backing strip, in this case a so-called in-place lamination process, producing a laminated (i.e., adhered) hook product. As an alternative to the use of pressure rollers, fig. 4D shows an extrusion head F that applies resin to the surface of the mold roll 80 by pressure. The extrusion head F has a contoured surface 480 spaced from the surface of the roll for making the base of the hook product.

As shown in fig. 4A and 4B, the profiling rollers consist of a series of dished plates or rings 250 mounted on a cooled central cylinder 251. The rings are pressed together axially to form a cylindrical surface. And isolation rings are arranged between the molding rings. And a cavity is arranged on the periphery of the forming ring arranged between the isolation rings. The cavities and mound or other structured cavities on the spacer ring are provided in a predetermined relationship to one another as required by the particular application, with the result that hooks are provided on the base in the desired relationship to one another. The profile roll shown in the figures consists of rings, but it is also possible to use discs provided with moulds at the periphery and through which cooling cavities run.

Because the hooks and the hooks are opposed in opposite directions, half of the rows of hooks are oriented in the direction of travel of the fastener, while the other half of the rows of hooks are oriented opposite the direction of travel of the fastener. As shown in the step of removing the hooks 12 from the impression 1 of fig. 5A, the hooks oriented against the running direction can be disengaged from the impression of the profile roll without significant bending. However, as shown in FIG. 5B, the hooks oriented in the running direction must be bent along the edges of the mold cavity when removed from the mold cavity, which slightly deforms them, resulting in them protruding from the base at a higher and steeper angle than hooks oriented against the running direction. Because of the small size of the hooks, the prior art hooks are easily cooled and set into a deformed shape. However, the hook chamber disclosed herein provides sufficient space for the hook portion to return to the shape of the cavity before the hook is completely withdrawn from the cavity, thereby reducing the tendency of the hook to set into a deformed shape.

In addition, to produce a more uniform set of hook elements, the hook elements can be passed under a knock-down roller 86, the spacing between the knock-down roller 86 and the take-up roller 87 being adjustable. The high or steep hooks can be pressed back to the same plane with the oppositely oriented hooks relative to the substrate by a knock-down roller. The knock-down roller 86 is placed adjacent to the location where the hooks are removed from the mold cavities so that the hook elements are also slightly softer, permanently deformed as they pass under the knock-down roller, and retain their new shape.

The mold cavities 1 are shown disposed about the periphery of the mold roll 80, and the moldable resin is supplied to the surface of the mold roll at the nip. It should be understood that the moldable resin may be supplied to the cavity in a variety of ways. For example, the profile roll may be fed directly from an extruder. After being conveyed along the surface of the mold roll, the resin is pressed into the cavity by a pressing roll. Alternatively, an extruder is mounted to compress the surface of the roller, with the extension of the nozzle surface conforming to the roller to maintain sufficient pressure on the extruded resin to fill the mold cavity with resin.

Other methods of supplying the cavity with the moldable resin may be used. For example, fig. 4C is a perspective view of an injection mold schematically showing the orientation of a cavity, and a moldable resin is injected into the cavity 1 formed on the injection mold 150, thereby manufacturing a fastening member by injection molding. The injection mold 150 is comprised of a series of mold plates 151 placed face to form a flat (or curved) surface with a cavity therein. The cavities may be provided in one or more mold plates. After molding, the entire mold is opened, the hooks are removed from the mold cavities as the molded part is removed, and the entire mold is closed for the next injection cycle. Injection molding can be used to make the hooks directly onto a hard pad, which in turn can be attached to a separate piece. Injection molding may also be used to form the hook elements integrally with another component, thus eliminating the need to later attach the hook elements to the component.

The moldable resin can be any plastic depending on the application of the snap fastener. Polypropylene may now be preferred. Nylon, polyester, polyethylene, propylene, ethylene and copolymers thereof or other thermoplastic resins may also be conveniently used.

Other aspects of the invention relate to the use of three or more mold plates that form a mold cavity to manufacture a product. This technique is particularly useful when the hooks are made by a cross-over roll molding process or in a stationary mold extending across the plane of the assembled mold plates. These templates are preferably made using specialized photolithographic techniques. Alternatively, the template may be fabricated using EDM techniques, laser etching techniques, or other techniques.

For example, FIG. 6 is a cross-sectional view of the mold roll taken along radial plane 6-6 of FIG. 4A. Cavities extending in a direction transverse to the machine direction of the mold roll are formed using an actinic etching technique or other high precision forming technique such as a laser etching technique. As shown, this cavity is hook-shaped. However, other shapes of cavities may be used if it is desired to make other fasteners, or even parts that perform other functions.

In fig. 6, the mould cavity is formed by a number of disc-shaped mould plates assembled on top of each other in a face-to-face relationship on a roll axis, thus forming the surface 110 of the mould roll. Depending on where the contour of the desired cavity is to be formed, different amounts of material are removed from each adjacent die plate so that only a portion of the cavity is formed in each die plate. Typically, the cavity is formed in part by a through-hole in a die plate, and the cavity portions in the die plate on either side of the die plate occupy at least a portion of the thickness of the die plate.

As shown in fig. 6, all the templates have the same thickness. However, in certain preferred embodiments according to the present invention, the thickness of the die plate is different based on the application of the hooks, the profile and the density of the molded part. In some applications, the use of different thickness mold plates can make manufacturing more economical because less mold plates are required to form the mold cavity. Also, in other instances, the use of different thickness mold plates may allow for more efficient cavity formation, or for making ultra-small radius curves and/or smooth transitions. In some important cases, as the radius of curvature of the product becomes smaller, a thin template is used for better surface formation.

When making the hooks, the die plate may be only 0.003 or 0.004 inches thick or thinner. According to the invention, in order to produce special parts using very thin mould plates, one or more thin and delicate mould plates are laminated together to form a strong mother plate before assembling into a stationary mould or roller mould, so that they can be easily mounted on a cooling cylinder without the risk of deformation. The forms may be laminated (i.e., bonded) together with brazing, high temperature permanent adhesives, or other means.

Referring again to fig. 6, for example, in mold plate h, the cavity portion occupies the entire thickness of the mold plate in regions 308 and 309. In the mold plate k, the cavity portion occupies only a portion 314 of the thickness of the mold plate to form the tip of the cavity.

In this example, each mold plate is generally different from its adjacent mold plate, and the mold cavity is formed only when the mold plates are stacked together. In this way, hooks can be made in the transverse direction of the die plate (transverse to the machine direction in the case of roller dies).

Hook elements having a flat surface can be produced with this technique. However, it is preferred to produce hooks having a partially or fully rounded surface from the base to the tip. For example, the top surface of the hook tip is sharpened to a point such that the top of the hook has a wedge effect that facilitates entry of the top into the surface of the mating fabric.

Figures 7A-7K schematically show cross-sectional views of a series of rings corresponding to rings a to K of figure 6. Loop a has only a small portion of the outer side 300 removed to form a portion of the hook back side 400. Adjacent loop b has a cavity 301 forming an adjacent portion of the backside of the hook. The progressively higher cavities form corresponding portions of the backside of the hooks at loop h.

In loop h, cavity 308 forms a portion of the hook base with a reduced height, indicating a transition to the other side of the hook. The cavity 309 forms the starting point of the hook top. In adjacent loops i, cavity 310 is reduced in height, indicating that the base of the hook is shortened, while cavity 311 forms a downwardly curved hook portion. In ring j, cavity 312 is the rearmost portion of the base, while cavity 313 is adjacent the tip of the hook. Finally, the cavity 314 forms the tip of the hook in loop k. There is only one cavity in this block template, since ring k does not form any part of the base.

The techniques described above can be used to optimize the shape of the selected region, particularly in the h, i, j, k regions. Fig. 8A and 8B illustrate another manner of forming cavities using a photolithography process in accordance with another aspect of the present invention. The sides of the cavities 300-314 in fig. 7 are straight sides used to produce hook elements with straight sides; the inherent tendency of photochemical etching, however, is to produce curved surfaces, resulting in the production of hook elements having curved edges rather than straight edges (as shown in fig. 8A and 8B). Because the hooks are formed in the mold plate H ', the cavity 309' has not only curved edges, but also a point where a wedge-shaped hook is created on top of the hook element.

Fig. 9A and 9B show a hook with a wedge-shaped hook tip, which is created by cavity 309' shown in fig. 8B. The tops of the hooks both have a two-sided wedge effect to separate the fibers or threads of the mating fabric so that the hooks dig into their surfaces, allowing the hooks to better engage the loops or fibers.

Fig. 10A, 10B and 10C show a hook, which is shaped by photolithography on a ring, and then a cavity is formed by the ring and a flat ring. One side of the hook is curved and the other side is planar. As a result, a one-sided wedge is formed at the top of the hook, better penetrating into the loop.

The above-described technique of making a curved surface on the hook to form a wedge-shaped or smooth non-friction surface on the top thereof can be used to make a hook extending from the direction of the die plate (the machine direction at the time of roll casting) or the cross direction (the direction crossing the machine direction at the time of roll casting).

One advantage of making hooks with the above described method of aligning the hooks in a direction that the profile rolls intersect the machine direction is in the making of the hook appearance. Conventional hook-style straps are often used in an orientation where the hooks are not pointing to their optimal orientation. In this case, the laterally molded hooks provide the hook tips on the hook strip with the best guidance for engagement with the loops or fibers.

The sectioning technique described with reference to fig. 6-8 is advantageous in that it enables the production of hooks that vary along the length of the product to use different shapes and sizes of fastener elements under different conditions. Preferably, the size and shape of the hooks similarly vary based on the circumference of the tool as shown in FIG. 10. Also, under certain conditions, it may be desirable for the hook dimensions to vary in the machine direction. In this way, according to a predetermined pattern, a hook of varying size can be obtained that is arranged alternately in two directions. In some embodiments, adjacent hooks are aligned at 90 ° to each other in a repeating pattern in both directions. The machine direction hooks may also alternate with cross direction hooks according to a predetermined pattern to reduce the directional sensitivity of the product.

Using the method described above, the present invention enables the hooks to be aligned at an angle relative to the machine direction or its cross direction, i.e., in a helical or angled configuration, such that the projecting portions of the hook elements extend in both the cross direction and the machine direction. For example, in some embodiments, the loops are formed such that the hooks extend in a direction 45 ° from the machine direction. Fig. 11A and 11B are partial perspective views of the mold roll surface showing the location and orientation of the mold cavities, which schematically illustrate these different orientations. Similar orientations (e.g., along and against the template) can be achieved with a combination die.

Thus, the present invention can be used to actually produce hooks that differ in machine direction orientation and pattern relative to the mold roll. The techniques described herein make it feasible to produce palm tree hooks (hooks with two tips), trifurcated hooks (hooks with three tips) and quadturcated hooks (hooks with four tips).

The molding process of the hook shown in fig. 6 will now be described. Fig. 6 shows the same profile as described in fig. 1, rotated 90 ° with respect to the machine direction.

As mentioned above, the wide base allows the hook to be ejected and return to its original shape before leaving the cavity in order to reduce distortion. Another feature of the present design is that a wide base is also provided in the machine direction. This effectively produces a base that is wide in both the hook direction and the direction perpendicular to the hook, thereby effectively producing a true pyramidal base that tapers inwardly around.

Fig. 12 is an end view of a hook component die utilizing the pocket portion of fig. 8, but with the taper oriented 90 to the direction of the hook profile (i.e., end view). In certain preferred embodiments, the taper is preferably from 0.6: 1 to 0.8: 1 or higher. In certain preferred embodiments, however, the taper in the end view preferably matches the profile of the side view, with a taper of 1.2: 1. This provides a very stable base which, because of its robustness and good fixation, results in a better hook performance. Of course, the invention can be made with other shapes of hook outer profiles.

The taper shown in fig. 12 also makes the hook easier to demold. In accordance with the present invention, the taper of the base is selected to simultaneously demold the transverse hooks, provide a large base cavity for the hook portion of the hook member to return to the molded shape during demolding, and provide a hook of small overall height and high strength.

In addition to being able to produce a base that tapers in both the machine direction and the transverse direction, this technique can also be used to create curved surfaces and to produce a conical molded base as shown in fig. 13, 13A, 13B and 14. The conical hook is strong and in some important applications, the smooth surface avoids friction from sharp corners or flat surfaces.

In some cases, the rounded surface of the hook also reduces the chance of brittle failure as compared to a sharp corner. Hooks without sharp corners are not brittle and they return to their original shape when disengaged. Moreover, such a circular hook can be engaged and disengaged more times before failure.

The dedicated photo-etching technique has a very novel use in the fabrication of the large number of small hooks (or micro-hooks described below) with conventional and transverse orientation described above.

In fabricating a mold having the hook profile of fig. 6, in accordance with this aspect of the invention, a photochemical etching technique is used. For a given mold plate, a flat plate is selected to form the cavity or a portion of the cavity. For the profile roll, the plate is sized to form one ring of the roll. 17-7 PH stainless steel or other suitable metals may be used. A photosensitive medium, a photoresist material, is applied to the template and the photoresist material is exposed to a radiation (i.e., light) source through a compensating mask, where the metal to be removed forms the cavities. The mask blocks a predetermined portion of the light to expose the photoresist material to a predetermined pattern of light. The mask is positioned between the light source and the photoresist material. In particular, the mask may be applied directly to the photoresist material.

Currently, the photoresist material is preferably a positive-acting photoresist material. Upon exposure to light, the positive-acting photosensitive resist material cures onto the template. The remaining portions of the photoresist material not exposed to light are then removed. Alternatively, a negative effect photoresist material may be used. The negative-acting photoresist material is that portion which is removed when exposed to light. The remaining portion of the photoresist material not exposed to light remains on the template.

As in fig. 15, the dashed line represents a mask that is located above the contour of the desired hook cavity represented by the solid line. The portion of the photoresist to be removed is within the dashed area. After the photoresist is irradiated with light, the photoresist is removed to reveal a pattern of the article. Then, the metal plate is placed in an apparatus, and the metal not covered with the photoresist material is removed by etching. As is common in photochemical etching, a jet of an etchant, such as an acid, is used. After etching, what remains is the metal plate portion covered by the photosensitive scandium etch.

As shown in fig. 15, regions a-G indicate different portions of the cavity shape and schematically indicate different portions of the corresponding mask shape. In some areas, the dashed lines of the respective masks and the edges of the desired cavities generally coincide, but in other areas this is not the case.

For straight regions (e.g., region B in fig. 15), the edges of the corresponding mask generally conform to the straight lines of the cavity profile used (the shallower the etch, the tighter the fit). However, in the curved region, the lines of the mask are offset more from the used profile. The more the bowing, the greater the difference between the mask and the desired profile. The effect of the adjustment compensation is opposite to the effect of the adjustment compensation of the concave bending at the place where the edge of the cavity is required to be bent in a convex shape. In summary, when convex edges such as the edge at A are etched, the mask is calibrated to be smaller than the cavity size because the etching action is relatively concentrated for a given perimeter cavity compared to a straight edge. For concave edges, such as the edge at C, the outer edge of the mask is enlarged in the opposite manner to compensate. In region E of fig. 15, the surface is more convex (i.e., smaller radius) than the surface in region a, so the adjustment compensation is greater and the mask defines a smaller cavity size.

Adjusting the profile of the mask forms tips in regions D and E. Sharp corners tend to round off during photochemical etching. Thus, the modified profile presents sharp points due to the desire to form a small rounded tip shape. Region F is a linear region, similar to region B, while region G is similar to region a. Thus, in this example, the contour of the mask is different for all of the curved regions of the hook than for the final hook cavity.

Fig. 15A shows a cross section of metal after etching, taking advantage of the tendency to produce curved surfaces rather than flat surfaces during photo-etching. This results in a perfectly circular shape, especially at the edge of the hook top. The rounded shape provides a surface that is easier to pierce into a mating fabric than a flat surface. Moreover, in important applications, the naturally occurring rounded shape of the etched template surface is used to create a smooth curved surface across several adjacent templates.

As is well known in the art of photochemical etching, the particular mask correction technique, photoresist material, and etchant are selected based on the particular metal being processed, the depth of metal removal, and other conditions. For details of the process, reference is made to the paper "Photo-Chemical machinery funding fuels with Three Unique Applications" by doctor r.bennett, published by the society of Manufacturing Engineers (the society Manufacturing Engineers) in 1976; publication No. PCMI1000 by the Institute for photochemical etching (Photo Chemical Machine Institute), entitled "What is Photo Chemical mechanical processing and What It Dofor You"; a Conference publication of the Society of Carbide and Tool Engineers (the Society of Carbide and Tool Engineers) having the name "national Machining centers of the Conference Held centers 2 and 3,1985", commonly owned by the Medicut Research Associates, Inc. and the Abrasive engineering Society. And references cited in those papers. The articles specifically cited above are hereby incorporated by reference.

FIG. 16 illustrates another correction mask in which straight lines and sharp corners are used to provide a smooth small radius surface in the part being fabricated. The shape of the artwork is designed to be small square near the tip of the hook where one smoothly curved portion transitions to the opposite smoothly curved portion.

Various techniques may be employed to obtain the desired different cavity profiles in the mold plate. For example, in making a cavity or cavity portion that penetrates the mold plate, it may be desirable to perform the photochemical etching from both sides of the mold plate to reduce the overall concave curvature of the etched surface and, in some cases, to provide an overall convex surface. In some cases it may be desirable to etch the edges of the template at different times to create different shapes on the two sides of the template. The etching liquid is either sprayed onto the surface to be etched or introduced in the form of a vapour in order to increase its local effect.

As shown in fig. 17B, the overall height H of the hook according to fig. 2A-2D is 0.008 inches. The radius of the tip surface is about 0.0008 inches. For comparison, this hook is shown alongside a small hook having a height H of 0.015 inch as shown in FIG. 17A. The hook shown in fig. 17B is referred to as a "mini hook" because the height is 0.010 inches or less. In various applications, the hooks are made by photo-chemically etching the sides of the stencil to depths of 0.003 inch and 0.005 inch. The hook of fig. 17C is similar in construction, but the hook has a smaller projection and the top of the hook extends substantially horizontally. This profile represents a different choice in terms of displacement volume and hook shape, which may be more desirable in some cases. The replacement volume of the hook shown in fig. 17C is less than that of the hook of fig. 17B because it omits the downwardly projecting portion of the tip. For example, this form of hook is useful when a less flexible nonwoven fabric is used in conjunction with fibers that are tightly bonded to the material. In some cases, the hooks shown in fig. 17C provide effective engagement when used in tight engagement with a row of hooks projecting in the opposite direction.

The ability of the photo-etching to impart other important improvements in shape and effectiveness to the hook and loop fastener ensemble used in engagement with the loops.

For example, as shown in fig. 18, a palm tree hook 400 has two hook portions 402 extending from a common shaft 404, each hook terminating in a distal most tip 406 at the outermost edge of the hook portion and having other features to enhance engagement and retention with loops. Dashed line 407 in fig. 18 represents the central axis of one of the hooks 402.

The hook tips 406 enhance hook-to-loop engagement as seen in the x, y plane profile, with the hook being planar on one side as shown in fig. 19 and end view 21 and the hook being symmetrical in the Z direction as shown in end view 21A. The tip 406 has a tip radius of about 0.001 inch, as shown in FIGS. 19A, 21 and 21A, and an acute angle α is formed between the sides of the hook portion 402_x，y、α_z1And alpha_z2. The tip can penetrate between the engaging loop and the remainder of the loop-like fastener member outside the loop, thereby engaging the loop in a loop capture region 408 between the stem 402 and the hook tip 406. Importantly, the tip 406 is very close to the laterally outermost edge 410 of the crook portion 402, which allows the tip to engage directly with the loop adjacent the loop capture area from above the hook. The improved engagement probability of each individual hook of a hook and loop fastener increases the rate of engagement of a row of hooks, i.e., the total percentage of hook rows engaged with loops at any given time. High engagement rates generally result in better fastener performance.

As described immediately above, the configuration of the tip 406 and its location that provides good initial engagement with the loop results in a small cross-sectional area of the tip. This provides extreme flexibility at the tip, which gives the tip the ability to "snake" in the middle of the loop fibers during the engaging movement of the fastener component, which further increases the likelihood of engagement with the loops. However, while somewhat flexible, the structural features of the hooks allow the hooks to grip the loops once they are engaged. This is particularly important in applications where the hook is so deformed that the engaged fastener is easily separated to release the engagement.

Certain structural features of this embodiment improve the gripping loop performance of the hook portion 402. For example, the inner surface 412 of the hook (i.e., from the tip 406 to the apex 414 or the highest point on the underside of the hook) is at a steep angle relative to the base of the fastener. This helps guide the initially engaged circumferential rod 402 from position a (immediately inboard of the tip 406, fig. 19A) to the bending section 404 where bending resistance is high, as in position C (fig. 19A). The slope of the surface 412 passes through the tip at a line 416 tangent to the tip 406 through the apex 414 and perpendicular to the plane of the fastener baseThe angle psi between lines 418 indicates that psi is about 45 deg.. Surface 412 is also concave upward, making the lower surface of the hook steeper closest to the tip, resulting in only about 25 ° of an angle ψ between line 420 tangent to surface 412 closest to the tip radius and line 418₁. The inner surface 412 of the hook portion is preferably elliptical and is formed by an ellipse having a major axis 419, the angle of inclination α between major axis 419 and the vertical line of the base_eNot greater than 30.

Generally, hook and loop fasteners disengage when a pulling force is applied between mating engaging components in a direction perpendicular to the plane of their bases. Under this pulling force, the ring 421 with the pointed tip engaged tends to move along the tapered surface 412 to the apex 414 under the applied force without applying significant stress to the hook tip. Lateral distance δ from the ring joined at apex 414 to rod 404₁Very small, only the lateral distance δ from the bar 404 to the laterally outermost edge 410 of the hook₂25% of the total. This moves the engaged loops towards the apex 414, allowing the loops to remain well in place under the force causing a bending moment in the hook portion because of the short moment arm. In addition, the vertical cross-sectional thickness t of the crook portion at the apex 414_vGreater than the thickness of the section of the hook near the tip, t_vAbout a lateral distance δ₂65% of the total. Due to its large cross-sectional thickness, the hook portion of the hook resists "flattening" (i.e., bending in the plane of the hook to move the hook tip 406 away from the fastener base to open the underside of the hook).

As shown in fig. 19A, when engaging and gripping the loops 421, the structural features of the hooks 402 cooperate to firmly grip the loops so that the loops disengage when a slight force is applied in a direction (normal) perpendicular to the plane of the fastener base. At a, the vertical force exerted by the loop 421 on the hook 402 is substantially parallel to the surface 412, so that the normal force exerted by the loop on the hook is negligible. Conversely, the loop will move to position B under this force, where face 412 is less steep than at position A, but the hook width, thickness and corresponding bending strength are high, so that the hook can resist the force applied by the loop without substantial deformation. In position B, the face 412 is still a sloped surface so that there is still a component of the force applied along the face which continues to move the loop toward the highest point on the lower surface of the hook, i.e., the apex 414. Due to the configuration of the hook, the bending stiffness and strength of the hook increases gradually from the tip 406 to the apex 414. This gradual increase in bending strength is accompanied by a gradual decrease in the slope of the faces 412, which together urge the hooks 402 to grip the loops 421. The increase in hook cross-sectional area in a plane perpendicular to the central axis of the hook preferably increases linearly as a function of the distance of the tip 406 along the central axis.

As shown in fig. 20 (which corresponds to a cross-sectional view of the embodiment shown in fig. 21), the hook portion 402 has a planar side 422 and a curved side 424. Sides 422 and 424 meet at the hook apex as a wedge-shaped edge 426 which provides a good entry profile for piercing into a large loop in a mating buckle assembly. Figure 20A shows a cross-section of the hook 400 "of figure 21A as viewed from the direction 20 in figure 18,

as shown in FIG. 21, the overall length of the hook 400 from the base to the tip tapers in thickness in the z-direction, out of the plane of the hook. The sides of the hook are convex so that the cross-section of the hook is thicker at the center and thinner at the opposite edges along the central axis of the hook. Such a shape is particularly suitable for formation by controlled etch depth using a photo-chemical etching technique, in part because the etch tends to form a curved surface, deeper at the center of the etched region, as described above. Tapering in the plane of the hooks as well as out of the plane of the hooks (i.e., a "three-dimensional" taper) provides easier removal of the hooks from the mold cavity and less resistance to removal of the product from the mold than hooks that differ in only two dimensions and have opposing parallel sides. In order to provide the proper profile for demolding, a hook of constant transverse thickness must have a continuously decreasing profile width in the hook plane. The three-dimensional tapered hook of this embodiment can utilize the variation in lateral thickness and is therefore not limited by the shape of the demolding profile. In the demolding process, the transverse thickness is reduced in a conical shape, and the hook can be moved out of the plane of the mold by a method of twisting a rod and the like, so that the demolding residual deformation of the hook is smaller. Some hook profile shapes that are limited to two parallel sides due to demolding difficulties and thus not feasible can now be practically realized.

Fig. 21 also illustrates a gradual decrease in the transverse thickness of the hook near the tip 406. Included angle alpha_zBut is only about 30. Thus, the hook thickness is dramatically reduced in the area where the loops are first engaged, further enhancing the penetration of the tips into the loop pad and fiber engagement.

As shown in FIG. 21A, the hook 400' has a profile that conforms to the profile of the hook 400 shown in FIG. 18, is symmetrical in the z-direction, and has two identical curved surfaces that intersect line 428. The hook 400' is molded in a cavity formed by two adjacent, actinically etched mold plates. Because the mold cavities in the mold plates are highly repeatable and the cavities produced by the photolithographic process are precisely sized and shaped as described above, adjacent mold plates are easily aligned. This produces a row of hooks on line 428 with little or no offset. The hook is tapered on both sides to sharply reduce its cross-sectional area along the hook, allowing hook profiles that were previously difficult or impossible to demold.

As with the hook 400 "of fig. 21B, the stem strength is higher in use, and immediately below the hook, the thickness taper of the hook is increased to produce a stem portion with increased lateral stiffness. This significant variation in hook thickness can be accomplished by using a photolithographic etching technique in a single mold ring by varying the etch depth of each hook cavity in the ring, by multiple masking and etching steps instead of aligning adjacent rings. The smooth transition of hook thickness achieved by the photochemical etching reduces undesirable stress concentrations at the sharp corners and avoids flat, horizontally upturned hook surfaces that can resist penetration into dense ring pads.

With the high precision positioning of the removed portions produced by photochemical etching, several new hook shapes are produced with the stems or pedestals oriented in the direction of the plane of the template and having projections or hooks that intersect the machine direction or intersect the template. Fig. 22 and 23 show a double hook 450 with hook portions 452a and 452b projecting along different planes. The hook portion 452a extends out along the plane of the form, similar to the hook portion 402 in FIG. 18. However, the hook portions 452b are oriented generally perpendicular to the plane of the forms, and are formed in four adjacent forms. Dashed lines 454, 455 and 456 in fig. 23 represent interfaces between the mold plates, illustrating how the hook 452a and bar 458 are formed in the two mold plates, while the distal region 460 of the hook 452b, including its tip, is formed in third and fourth mold plates that are thinner than the two mold plates forming the bar in order to achieve precise formation of the hook tip. Because of the precisely controlled nature of the photochemical etching, the curved outer surface is blended at the template-template interface, avoiding sharp corners of the hook pocket that may interfere with solidification during pull-out.

Fig. 22 and 23 are greatly enlarged views (e.g., the overall height of the hook is less than about 0.025 inches in some applications). In order to maintain the desired overall pattern of hooks, adjacent forms must be precisely aligned. For example, if the stencil forming the distal ends of the hooks 452b is laterally offset from the other stencils by only 0.005 inches, the hooks 452b are no longer sharp. Even an offset of only 0.002 inch creates a locked mold condition such that the solidified resin cannot be pulled completely out due to the local interruption in the continuity of the taper of cross-sectional area from the base to the tip. The precisely aligned adjacent hook row mold plates are laminated together, creating a single thick mold plate, reducing the potential for misalignment when repeatedly assembled. One template forming the complete outer contour may be obtained by using high temperature adhesives or brazing.

In another embodiment, forms of varying thickness are used, thin forms being preferred for use where the variations in geometry and shape are large, and thick forms elsewhere.

Fig. 23A, 23B, and 23C illustrate other suitable hook configurations. In each of these figures, as in fig. 23, the dashed lines represent the interface between adjacent templates. Fig. 23A is a top view of a hook 470, the hook 470 having a rod 472, the rod 472 being aligned in the direction of the mold plates and molded into two adjacent mold plates. Hooks 474 extend from the rods 472 in a direction generally perpendicular to the above die plates, and are formed in 4 die plates, as with the hooks 452b in fig. 23. Figure 23B shows a hook 476 having three hooks (i.e., a trident) 478a, 478B, and 478c, the hooks being angled at 120 ° relative to each other and extending from the same bar 470. Fig. 23C shows a four-hook 482 having hooks 484a,484B, 484C, and 484d extending from the same shaft 486 at 90 ° to each other, the hooks 476 and 482 of fig. 23B and 23C being particularly well suited for use in multi-directional force applications where shaping is not possible with the earlier linear EDM cavity molding techniques. Hooks with more hooks can be conveniently made with the proper configuration and alignment of the cutouts made with the photolithographic technique.

In order to machine a cooled mold for molding plastic fasteners, particularly the hooks of touch fasteners, it has been found advantageous in the manufacture of fastener products and in the construction of fastener products themselves to use the above-described photochemical techniques (etching, milling or cutting) of a metal template, particularly a copper beryllium alloy template, or to use other high precision metal forming techniques such as EDM, electrochemical machining laser cutting of cavities followed by slight photolithographic deburring or smoothing of the surface to provide a fine and precise finish of the mold surface with few nodules or protrusions. It has been found that a surface roughness of less than about 75 microinches, and preferably less than about 60 microinches, produces important new results.

For example, with the interior surfaces of the hook cavities being so smooth, it has been found that the resin fills the cavities more freely than in commercial molds made by other methods now available. This improved melt flow reduces the pressure required to fill the cavity, allowing the hook cavity to be filled more quickly even when the cavity is small or bends so much that flow is restricted.

In addition, it has been found that a smooth cavity surface reduces the force required to demold, which reduces the likelihood of permanent deformation or distortion of the hooks. These features have been found to enable higher line speeds when hooks are made by rotary molding according to the Fischer process (see U.S. patent 4,794,028 or YKK equivalents, U.S. patent 5,393,475 or 5,441,687, which are incorporated herein by reference). Similar advantages can be obtained by using surface finishing techniques in the fastener cavity when the fastener is produced by injection molding or other injection molding techniques.

These particularly smooth mold surfaces also substantially reduce tool downtime associated with cleaning the mold plates. In past commercial production, after the hooks have been released from the mold, the plastic resin readily adheres to the cavity surface, which is covered with a resin deposit that increases in thickness over time. Finally, if the tool is not removed for cleaning, the profile of the hook feature of the mold cavity is damaged.

For example, hook forming dies for the Fischer process today are made up of up to 2000 or more ring die plates, typically half as many hook die plates as rings. Using different cleaning processes is laborious and time consuming. It has been found that because of the very fine surface roughness described above (i.e., less than 75 microinches), there is little resistance to pulling the hook out, leaving little resin in the mold cavity. This reduces tool downtime and cleaning frequency, resulting in substantial savings in production costs.

It has also been found that the above described technique is also of great advantage when used on the outer contour of the edge surfaces of a template, for example on the outer diameter of the rims of mould rings stacked in a Fischer process or of templates fitted together in an injection moulding process. The outer edge surfaces of the mold plates refer to those surfaces which together form one side surface of a fastener base in the form of a strip of a board to which hooks or other fasteners are integrally attached. By using a template with a very low surface roughness, the substrate of the molded article can also be given a correspondingly fine surface finish. Since the molten resin easily flows over these outer mold surfaces to fill the cavity, it is possible to use a high linear velocity. Since the resin flows and spreads uniformly to form a uniform thickness of the base even at a high speed, the performance can be made uniform over the entire width of the base tape. For example, the use of form rolls produced by the above technique may enable a 50% or more increase in line speed of the continuous molding process as compared to molds currently used and produced by conventional EDM methods.

Another extremely important feature of the invention is based on the recognition that, despite the fact that the cavities are closely aligned along the edge surfaces of the die plate, it is possible to maintain a high dimensional accuracy in the overall outer contour shape of all the edges of the die plate and thus obtain unusual benefits. This can be achieved using the photochemical techniques described above with high part consistency. By appropriate control of the mask tolerances and etching process, as described above and in the incorporated photochemical technology references, it is possible to produce outer diameters as high as both the concentric inner and outer diameters and as high as roundness and accuracy. When the desired cavity is produced, the rings are concentrically stacked with all of their inner diameters on the same mandrel to form a mold roll having a highly accurate cylindrical outer surface.

With this photochemical technique, a 12 inch diameter mold ring is precisely no larger than 0.001 inch in diameter, or perhaps as small as 0.0005 inch in diameter. By accuracy or error we mean the average value of the dimensional change.

In another case, after cavities are formed in the mold plates by EDM laser cutting or photochemical techniques and the plates are assembled in stacks to form the rollers, the rollers are machined in their entirety to a final diameter tolerance of within 0.001 inches, and the burrs are removed by slightly laser etching in the hook cavities. While it is estimated that the burrs at the edges of the cavity are not removed as such, it has been found that the work hardening characteristics of these burrs make them easy to remove by chemical etching without significantly altering the desired mold plate edges or cavity shape.

In each configuration, the outer surfaces of adjacent rings (e.g., rings 502 and 504) are precisely aligned, as shown in FIG. 24. The burnishing roll thus produced has no detrimental asperities at the loop-to-loop interface (e.g., interface 506), resulting in a uniform hook fastener tape surface and thickness.

It is important to avoid detrimental asperities at the interface between the die rings and to maintain the roll diameter error within 0.001 inch, preferably less than 0.0005 inch, to produce fastener elements having a base web of very small thickness. Typically, the thickness of the component substrate of a fastener is compromised by the possibility of undesirable contact between the mold roll 508 and the resin-pressurized pressure roller or extrusion head 510And (4) limitation of unevenness. Polished mold rolls are expensive and incidental metal contact with the surface of the mold roll can result in substantial damage to the mold cavity. However, the dimensional accuracy of the profile rolls produced by this technique allows the production of a sub-base thickness t_bA base strip of less than 0.003 inch, and even more preferably 0.002 inch or less (see fig. 18).

This "ultra-thin" hook strip (i.e., thickness t)_bA base strip of 0.003 inches or less) provides unique advantages for hook-and-loop engagement. The stiffness of the base tape for a given resin is proportional to the third power of the thickness of the base tape. The ultra-thin base tape is more flexible than a base tape having a thickness greater than 0.003 inch. The reduced stiffness greatly improves the performance of the low profile hook component since it is less likely to accidentally disengage from its mating loop component. For example, ultra-thin hook tapes have been found to be extremely resistant to "lifting" or "pop-off", which is of particular concern when used on clothing. Because of the imbalance in stiffness between the loop and hook portions of the fastener base, lift-off is essentially a tendency for the fastener to disengage when twisted or twisted in some manner (e.g., in some towel applications when the baby is bent over badly). Many loop portions are flexible and if the hook engaging members are not as flexible, the hooks tend to partially disengage when the loop portions are bent and twisted in contrast while the hook portions remain relatively rigid. With the technique of the present invention, the rigidity of the ring portion and the hook portion can be made substantially the same. Thus, the hook portion can more easily bend with the bending of the mating loop portion, thereby always remaining in contact with the loop portion, better engaging together.

The ultra-thin, soft base tape also reduces skin irritation in some towel applications because it avoids rubbing against the rigid surface of the baby's skin. In addition, the material savings in the base tape is considerable because the thickness of the base tape is reduced by 30% or more because the material costs make up a significant portion of the cost of the continuously molded hook and loop fastener base tape.

In a preferred embodiment of the ultra-thin base tape, a certain quality grade of polymeric resin is selected. For example, resins having a melt flow index of greater than 5, preferably greater than 10, and in certain preferred embodiments, particularly with miniature or microhooks, a flow index of up to 20 or more are selected. Resins having such high melt flow indices provide improved hook cavity filling and provide important advantages when using cooling forms made of beryllium copper alloys or other high thermal conductivity materials. A resin having a high melt flow index can quickly fill the hook cavity before the resin is cured. This allows for better forming of the fastener and allows for higher line speeds. In addition, a high melt flow index results in a uniform distribution of resin across the width of the mold, resulting in a uniform and consistent thickness of the base tape.

Preferably, the resin selected for molding the ultra-thin hook base tape has a tensile yield strength of about 5,000 to 5,300 lbs/inch²(psi) or greater to enable the base tape to withstand tensile loads imposed thereon in high speed demolding and subsequent operations without yielding or deleterious deformation. Preferably, the resin is also selected to have a shear resistance or toughness that is easy to demold and can be extended by about 10% or more without permanent hook deformation.

Depending on the application, polypropylene, polyethylene and polyester resins and their copolymers are examples of materials used to make ultra-thin hook tape, but other thermoplastic, even thermosetting, resins may be used. Preferred polypropylenes are KC-732-P and E-1120-Z, available from Monell USA and Epsilon Polymers, respectively.

The ability to produce thin, high contact force touch snap closures at high speeds has a significant impact on the cost of such closures and therefore their applicability to general packaging applications, where large area closures are required, such as in the building and signage industries, and to inexpensive disposable products.

The above-described techniques and configurations provide improved flow, control, and moldability of the molten resin. Another aspect of the invention is the specific use of copper-based alloys with high thermal conductivity as the template or ring. A particular aspect of the invention is the use of hardened copper beryllium alloys as the metal for the template.

The high thermal conductivity metal enables the small molded fastener to be cooled rapidly, and the resin of the fastener base comes into contact with the edges of the mold plate having high thermal conductivity during molding, resulting in rapid heat conduction to a coolant, such as an internally circulating coolant for cooling the mold plate. Specifically, the thickness t of the base of the ultra-thin fastener base layer_bLess than 0.003 inches, so the heat capacity is small and it is particularly easy to cool quickly. This further results in increased molding or line speeds, a significant reduction in production costs, and thus allows the hook fastener product to be used in many applications where cost is a concern.

Using the technique of the present invention, the cavity can be advantageously arranged into a new, previously unusable pattern by virtue of the cavity forming capability of the photochemical etching, as shown in fig. 25. For example, the cavities can be axially stacked within a mold plate, as shown by cavities 550 and 552, which overlap in mold plate 554 by a distance L0. Stacking the cavities produces a hook and loop tape product with a very high density of rows of hooks and a high final performance. In addition, different shapes of hook and loop fastener elements can be arranged in one die surface as shown in fig. 25.

In light of the above-described technology, it has been fortunately discovered that copper-based hardening alloys such as copper beryllium provide desirable cooling properties for use in molding contact snap hooks, while allowing easy etching of molds having exceptional surface finish, dimensional accuracy and small dimensions. The ability to photochemically form the mold ring or to slightly chemically etch the surface to remove burrs or to clean the surface without significantly affecting the shape of the molded template is a great advantage.

Thus, it can be seen that the material of the mold loops, the specific hook dimensions and resulting tolerances, as well as the particular molding techniques used to achieve them, particularly the geometry and dimensions of the fastener product, including the thin base strip and the specific orientation and shape, provide a great deal of consistent improvement in the touch fastener industry as well as in the tooling and method of making the fastener.

It should be understood that many aspects of the present invention are also useful in molds having movable parts that release the molded product rather than fixed parts.

The scope of the appended claims includes other embodiments.

Claims (76)

1. A method of molding a plurality of components (12) extending from a common base (10) using a plurality of face-to-face positioned mold plates (250), the steps comprising:

-making cavities (1) in the shape of said components in the sides of a plurality of mould plates;

assembling the mold plates together face-to-face to provide a mold surface, the sides of some of the mold plates closing the cavities in the sides of others of the mold plates;

placing the mold surface against the other surface and forming a gap (G) therebetween;

filling a volume between a mold surface and the opposed surface with molten resin; and

after the resin is cured, ejecting the molded assembly and the substrate integral therewith from the mold surface;

characterised in that the cavities (1) are made by a photo-chemical technique using a mask on the sides of the template, the shape of which is similar to but different from that of the part of the component to be moulded or the desired profile of the component (see figures 15 and 16) to correct for the non-uniformity of the predetermined etching process used to etch the exposed metal of the template defined by the mask to provide the required cavities.

2. The method of claim 1 including making a touch fastener assembly (100) using a plurality of mold plates (250 or 151) placed face-to-face together, comprising the steps of:

-forming a cavity (1) in the shape of the fastener in the side of the mould plate;

assembling the mold plates together face-to-face to provide a mold surface, the sides of some of the mold plates closing the cavities in the sides of others of the mold plates;

placing the mold surface against the other surface to form a gap (G) therebetween;

filling a volume between the mold surface and its opposing surface with molten resin; and

after the resin is cured, the molded fastener elements and the integral substrate are removed from the mold surface.

3. A method according to claim 1 or 2, characterized in that a plurality of templates are etched using a suitable mask to make an assembly or fastener (fig. 6), and the templates are assembled to each other in the recorded order.

4. The method of claim 3, wherein at least some of the plurality of forms are stacked together to form a thicker form assembly.

5. A method according to any of the preceding claims, wherein at least two of the mould plates have cooperating cavity portions which together form a relatively sharp point (see fig. 9b, fig. 12).

6. A method according to claim 5, characterised in that the mould cavity (1) defines a hook component (12) of a hook-and-loop fastener, the point on the hook being located (figure 9b) for engaging a loop or fibre of another mating component.

7. The method of claim 6, wherein the sharp point is formed at the hook tip (fig. 9b) at a first location where the hook contacts a loop or fiber of the loop assembly moving against the opposite side of the loop.

8. The method of claim 7, wherein the sharp point (406) is at a distal tip of a hook of the hook for engaging and guiding a loop into a loop capture zone (408) of the hook.

9. Method according to claim 8, characterized in that the top of the hook is located in an area of an angle (α) smaller than 30 °.

10. The method of claim 8 or 9, wherein the forming method is adapted to produce a tip (406) that tapers to a relatively sharp point in both end and side views (fig. 18 and 21).

11. The method of any of the preceding claims, wherein the cavity is defined by a hook component of a hook and loop fastener having a hook terminating at a distal point, one or more edges of the mask forming the distal tip being of a larger dimension (D, 601) and one or more edges of the mask forming the concave curve being of a smaller dimension (E) (fig. 15, 16).

12. The method of any of the preceding claims, wherein the mold cavity defines a hook member (400) of a hook-and-loop fastener having a hook portion (402) terminating at a distal point (406), the inner surface (412) of the hook being concave to define a loop-capturing region (408), and one or more edges of the mask defining the concave surface being undersized (see fig. 15, E in fig. 16).

13. The method of any of the preceding claims, wherein the mold cavity defines a hook member (400) of a hook-and-loop fastener having a hook portion (402) terminating at a distal point (406), the upper edge of the hook being convex, and one or more edges of the mask defining the convex edge being oversized (see C in fig. 15, 16).

14. The method of any of the preceding claims, wherein the cavity defines a hook component of a hook-and-loop fastener, the hook component (fig. 19) having a hook portion (402) terminating in a distal tip (406), the tip portion being directed toward the base (10), and an inner surface (412) thereof defining an apex (414) that is closer to the stem (404) or base of the hook than to the tip (406).

15. The method of any of the preceding claims, wherein the mask defines a hook (fig. 19), and further wherein the mask defines a hook

(a) The outer profile of the distal end (406) of the hook portion of the hook is substantially sharpened in the plane in which the hook portion extends (fig. 19A), forming an included angle of less than about 30 °;

(b) in the vicinity of the tip (406), the central axis (407) of the hook portion is directed substantially downward toward the base;

(c) a radius of curvature of the concave inner surface of the hook gradually decreases along the inner surface (412) from the tip to the apex (414); and

(d) the apex (414) of the loop-trapping region (408) is located laterally closer to the rod or base (404) than to the tip (406) of the hook portion.

16. The method of any of the preceding claims, wherein the cavity defines a hook member (400, 12) of a hook and loop fastener having a crook portion (402, 14) terminating in a distal tip (406, 16);

(a) the positioning accuracy of the side surface of the template pointing to the gap is 0.001 inches at most, which is the average value outside the edge of the template;

(b) thickness (t) of the gap_b) Less than about 0.003 inches, thereby providing an ultra-thin molded fastener strip.

17. Method according to claim 16, characterized in that the sub-base thickness (t) is_b) Less than about 0.002 inches.

18. The method of any of the preceding claims, wherein the mold cavity defines a hook component (12) of the hook and loop fastener having a crook portion terminating in a distal tip, and the mold plate is formed of a hardened copper alloy.

19. The method of claim 18, wherein the alloy is beryllium copper.

20. The method of any of the preceding claims, wherein the mold cavity (1) defines a hook component (450) of a hook and loop fastener having a crook portion (452b) terminating in a distal tip, and wherein at least the crook portion of the hook extends in a direction at an angle to the plane of the mold plates, the crook shape being defined by a plurality of cutouts in the plurality of mold plates.

21. A method according to any preceding claim, wherein a given die plate is formed with cavity portions in each side thereof, said cavity portions being stacked offset from one another, the sum of the cavity depths penetrating the depth of the die plate being greater than the thickness of the die plate (see figure 25).

22. The method of claim 21 wherein the pockets define at least a hook portion of the hook and loop fastener, the effective overlap of the pockets providing a high density of hooks in the hook component.

23. The method of any of the preceding claims, wherein the die plate defines a mold roll to which molten resin is applied by an extruder (fig. 4 or fig. 4D).

24. A method as claimed in claim 23, wherein a pressure roller (82) forms a nip with the former roller, the extruded plastic forming a bank of molten plastic at the nip.

25. The method of claim 23 wherein the extruder comprises a nozzle that discharges molten resin under pressure against the mold roll.

26. The method of any of claims 23-25, wherein the template is cooled with a cooling fluid.

27. The method of claim 26, wherein the template is made of a copper-based alloy.

28. The method of claim 27, wherein the alloy is a beryllium copper alloy.

29. A method of making a plurality of modules extending from a common substrate (10) using a plurality of face-to-face mounted die plates (250, 151) comprising the steps of,

forming a mould cavity (1) in the shape of a component in the side of at least a number of mould plates;

assembling the mold plates together in face-to-face relationship to provide a mold surface, the sides of some of the mold plates closing the cavities in the sides of others of the mold plates;

placing the mold surface against the other surface and forming a gap (G) therebetween;

filling a volume between a mold surface and the opposed surface with molten resin; and

after the resin is cured, ejecting the molded assembly and the substrate integral therewith from the mold surface;

wherein the mold surface is formed by chemical etching to ensure a surface roughness of less than 75 microinches.

30. The method of claim 29, wherein the etchant provides a surface roughness of less than about 60 microinches.

31. The method of claim 31, wherein the actinic technique produces a dimensional error of less than about 0.001 inch in the side surface of each template.

32. The method of claim 32, wherein the photochemical technique produces a dimensional error of less than about 0.0005 inches.

33. A method according to claim 29 or claim 30, wherein the cavities are formed using a photochemical etching technique, the facing surfaces of the die plates are assembled and machined to the required dimensional tolerances, and the die plates are etched while in the assembled condition to remove burrs projecting into the cavities.

34. A method according to claim 29 or claim 30, wherein the cavities of the die plates are pre-formed, the die plates are then assembled together face to face and machined to the required dimensional tolerances, after which the die plates, whilst in the assembled state, are etched to remove burrs which extend into the cavities.

35. The method of claim 34 or 35, wherein the template is made of beryllium copper and the work-hardened burrs are removed preferably by an etchant.

36. A molding apparatus, comprising:

a series of face-to-face die plates (250) mounted together and defining a series of cavities (1) in the sides thereof, the cavities being shaped to form the closure members, and

an opposed molding member (510), the edge of the mold plate (250) and the surface of the opposed molding member (510) forming a molding gap (G) in which the sub-base (10) is formed integrally with the fastener member (12) when the cavity and the gap between the edge of the mold plate and the opposed molding surface are filled with an injection-moldable resin,

it is characterized in that the preparation method is characterized in that,

(a) the edge surface of the template (250) is directed toward the gap to form a positioning accuracy from template to template of up to 0.001 inches, average relative to the edge of the template, and

(b) gap thickness t_bLess than 0.003 inch, thereby forming an ultra-thin molded fastener strip.

37. The molding apparatus of claim 37, wherein said positional accuracy is at most 0.0005 inches.

38. A moulding apparatus as claimed in claim 37 or 38, in which the die plate is formed from a hardened copper alloy.

39. A moulding apparatus as claimed in any one of claims 37 to 39 wherein the mould plates are formed from beryllium copper.

40. The molding apparatus as claimed in claim 40, wherein the mold plate is made of a copper alloy containing 1.9% by weight beryllium.

41. A moulding apparatus as claimed in claims 37 to 41, in which the mould plates are circular and are stacked to form a cylindrical mould roll (80) against which the parts are placed for applying molten plastic to the mould roll.

42. The molding apparatus of claim 42 wherein the opposed elements comprise a pressure applying roller (82) forming a nip with a mold roll (80) through which molten plastic enters the mold roll, the nip (G) between the mold roll and the pressure applying roller being less than about 0.003 inches and determining the thickness (t) of the fastener substrate_b)。

43. The molding apparatus of claim 42 wherein the opposed component is an extruder face (480) which abuts the mold roll to form a gap (G) with the mold roll of less than about 0.003 inches which determines the thickness (t) of the fastener base_b)。

44. The molding apparatus defined in claim 42, wherein the opposed parts and the mold plate together comprise an injection mold.

45. The molding apparatus of one of claims 37-45, wherein a surface defining said fastener cavity has a roughness of less than about 75 microinches.

46. The molding apparatus of claim 46, wherein a surface forming said fastener cavities has a roughness of less than about 60 microinches.

47. The molding apparatus defined in any one of claims 37-47, wherein the surface defining said fastener cavities is a chemically etched form surface.

48. The molding apparatus of any one of claims 37-48, wherein the surface of the mold has an actinically etched profile shape.

49. A moulding apparatus as claimed in any of claims 37 to 48, in which the surface of the mould is a pre-formed surface having a chemically etched and deburred surface finish.

50. The molding apparatus of claim 50, wherein the pre-formed surface is a machined cylindrical surface machined on a lathe, milling machine or grinding machine.

51. The molding apparatus as defined in claim 50, wherein the preformed surface is a surface formed by EDM.

52. The molding apparatus as defined in claim 50, wherein the preformed surface is a laser cut surface.

53. A molding apparatus, comprising:

a series of face-to-face die plates (250) mounted together and defining a series of cavities (1) in the sides thereof, the cavities being shaped to form the closure members, and

an opposed molding member (510), the edge of the mold plate (250) and the surface of the opposed molding member (510) forming a molding gap (G) in which the sub-base (10) is formed integrally with the fastener member (12) when the cavity and the gap between the edge of the mold plate and the opposed molding surface are filled with an injection-moldable resin,

it is characterized in that the preparation method is characterized in that,

the template is made of a hardened copper alloy and the surface of the cavity is a chemically etched surface.

54. The apparatus of claim 54, wherein said alloy comprises copper and beryllium.

55. The apparatus of claim 54 or 55, wherein the surface roughness of the cavity surface is less than about 75 microinches.

56. The apparatus of claim 56, wherein the surface roughness of the cavity surface is less than about 60 microinches.

57. The apparatus of any one of claims 54-57, wherein the templates are pre-formed using actinic light techniques and assembled into a stack having a dimensional tolerance of less than about 0.001 inches as a whole.

58. The apparatus of claim 58, wherein the tolerance is less than about 0.0005 inches.

59. A hook element for engaging a loop element, the hook element comprising a base (10) and a plurality of hooks (12) engageable by the loops, the hooks being integrally moulded with the base, characterised in that the base is formed of a plastics resin and has a thickness (t) of_b) Less than about 0.003 inches.

60. Hook component according to claim 60, characterized in that the thickness (t) of the base is such that_b) Less than about 0.002 inches.

61. The hook component of claim 60 or 61, wherein the hook is molded from a thermoplastic material.

62. A molded hook (12) for use in a touch fastener supported by a base (10), the hook member having a base or stem portion extending from said base and having at least one crook portion (402, 452, 474, 478 or 484) integral with the base or stem portion and bent transversely from the top thereof, the crook portion being shaped to taper in the plane of the stem of the hook along a central axis (407) thereof toward a distal tip (406) thereof, the distal tip portion of the crook portion being transversely spaced from the stem or base to define a loop-capturing region (408) having an apex (414), characterized in that,

(a) in the extension direction of the hook, the hook portion is substantially tapered, forming an angle (alpha) of less than 30 DEG_x，y)，

(b) The central axis (407) of the hook portion is directed generally downwardly toward the base (10) at the hook tip (406),

(c) the radius of curvature of the inner surface (412) of the hook portion decreases from the tip to the apex, an

(d) The apex (414) of the loop-trapping region is located laterally closer to the stem or base than to the tip of the crook portion.

63. The molded hook of claim 63, wherein the apex of the loop-capturing region is spaced a distance (δ) from the tip of the crook portion₁) The distance (delta)₁) Greater than the lateral distance (delta) from the outermost portion (410) of the hook to the stem or base (404)₂) Two-thirds, preferably more than three-fourths, of the total weight of the composition.

64. A molded hook according to claim 63 or 64, wherein the thickness of the hook, out of the plane of the extension of the hook (fig. 21), tapers conically towards the tip of the hook portion.

65. The molded hook of claim 65, wherein the transverse profile of the distal portion of the hook (fig. 21) is generally tapered to form an included angle (α) of less than about 30 °_z1) And the tip portion is directed generally downwardly toward the base.

66. A molded hook according to any one of claims 63-66, wherein in the transverse profile curve (fig. 21), the hook portion has a straight edge (422) and a convex edge (424), the convex edge being curved in such a way that: the cross-section perpendicular to the central axis is relatively thick at that axis and thinner toward the upper and lower edges of the hook.

67. A molded hook according to any one of claims 63-67, wherein in transverse profile (fig. 21), the crook portion has two opposite convex sides (fig. 20A), such that a cross-section perpendicular to the central axis is relatively thick at the axis, tapering towards the upper and lower surfaces of the crook.

68. A molded hook according to any one of claims 63-68, wherein, in the vicinity of the distal end (406), the inner surface (412) of the crook portion forms an angle (ψ) with a line normal to the base₁)。

69. A molded hook according to any one of claims 63-69, wherein the inner surface (412) of the crook portion from the tip (406) to the apex (414) forms an overall angle of inclination (ψ) with a perpendicular to the base.

70. A molded hook according to any one of claims 63 to 70, wherein the cross-sectional area of the hook portion (402) increases substantially linearly as a function of the distance from the tip (406) along the central axis in a plane perpendicular to the central axis (407) of the hook portion.

71. A molded hook according to claim 63, wherein the upper surface of the crook portion is generally wedge-shaped.

72. A molded hook according to claim 72, wherein said wedge shape is formed by the intersection of a flat side (422) of the crook portion and a convex side (424) projecting to the other side.

73. A molded hook according to claim 72, wherein said wedge-shape is formed by the intersection of two convex sides of the crook portion projecting in opposite directions.

74. A molded hook according to any one of claims 63-74 wherein the inner surface (412) of the crook portion (402) is generally elliptical, the major axis of the ellipse forming an angle of no more than 30 ° with the normal to the base.

75. A moulding hook as claimed in any of claims 63 to 75, in which the hook is of a shape that can be moulded in a fixed mould and can be removed from the mould cavity by pulling on the hook without opening or removing the mould parts.

76. The molded hook of claim 76, wherein the hook has a smooth surface corresponding to the corresponding actinically milled surface of its corresponding cavity.