Abstract:
A method of making a touch fastener includes continuously introducing molten resin to a pressure zone at a peripheral surface of a rotating mold roll, such that pressure in the pressure zone forces some of the resin into an array of stem cavities defined in the mold roll to form resin stems while a remainder of the resin forms a base at the roll surface, interconnecting the stems. The method includes forming engageable heads on the stems to form fastener elements and introducing a quantity of discrete, loose fibers to the resin. The fibers pass through the pressure zone with the resin and become individually and separately bonded to the resin to become part of the base.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to touch fasteners with embedded fibers. 
       BACKGROUND 
       [0002]    In general, touch fasteners include two mating components that engage and substantially retain each other. Hook and loop fasteners include: a hook component having upstanding, hook type fastener elements; and a loop component having a surface of fibers or fiber loops capable of retaining the hook type fastener elements. Some hook type fastener elements have mushroom-like heads, while some are shaped like hooks defining crooks and extending in a particular direction. Hook-engageable loop components generally include knitted, woven, and non-woven textiles. A common example of a non-woven textile is a “spun bonded” textile made by spinning fine filaments of plastic resin (e.g. polypropylene) and distributing them in superimposed layers. The fibers are bonded to each other in random orientations with a fine, low-lying, nappy layer of looped and arched fibers exposed at the surface of the fabric. 
       SUMMARY 
       [0003]    In one aspect, a method of making a touch fastener includes continuously introducing molten resin to a pressure zone at a peripheral surface of a rotating mold roll, such that pressure in the pressure zone forces some of the resin into an array of stem cavities defined in the mold roll to form resin stems while a remainder of the resin forms a base at the roll surface, interconnecting the stems. The method includes forming engageable heads on the stems to form fastener elements and introducing a quantity of discrete, loose fibers to the resin. The fibers pass through the pressure zone with the resin and become individually and separately bonded to the resin to become part of the base. 
         [0004]    In some implementations, the pressure zone (e.g. a nip) is formed between the peripheral surface of the rotating mold roll and a peripheral surface of a rotating pressure roll. In other implementations, the pressure zone is formed between the peripheral surface of the rotating mold roll and a peripheral surface of the extruder. The fibers are generally introduced at an entrance to the pressure zone. The method may further include continuously introducing a flexible substrate to the pressure zone, where the base of resin is laminated to the substrate on the peripheral surface of the pressure roll, such that the substrate becomes permanently bonded to the base. The fibers may be continuously deposited onto the flexible substrate, which carries the fibers into the pressure zone, thereby exposing the fibers to the molten resin during formation of the base, and securing individual fibers to the resin. The method may include orienting the fibers for deposition of a pattern of fibers. In some instances, the loose fibers are introduced to the pressure zone as a continuous stream. 
         [0005]    By selectively choosing the fibers and introducing them to the molten resin, the resulting formed base may advantageously achieve a coefficient of friction (MIU) of between about 0.125 and about 0.4, a frictional roughness (MMD) of between about 0.01 and about 0.2, and a geometrical roughness (SMD) of between about 1.5 μm and about 7.0 μm. In one preferred implementation, the base preferably appears cloth-like and feels cloth-like by having a coefficient of friction (MIU) of between about 0.145 and about 0.16, a frictional roughness (MMD) of between about 0.009 and about 0.015, and a geometrical roughness (SMD) of between about 4.3 μm and about 6.7 μm. In another preferred implementation, the base preferably appears cloth-like, but does not necessarily feel cloth-like by having a coefficient of friction (MIU) of between about 0.1 and about 0.25, a frictional roughness (MMD) of between about 0.003 and about 0.02, and a geometrical roughness (SMD) of between about 1.5 μm and about 4.0 μm. Instead, this base may feel relatively smooth (e.g. as with plastic tape). The base may be opaque and the fibers may include a non-woven material, cotton, polyester, and rayon. 
         [0006]    In some implementations, the method includes continuously introducing a carrier sheet to the pressure zone along the peripheral surface of a rotating pressure roll. The fibers are deposited onto the carrier sheet, which carries the fibers into the pressure zone, thereby exposing the fibers to the molten resin during formation of the base, and securing individual fibers to the resin. The carrier sheet is then removed the from the molded base. 
         [0007]    The method may include depositing the fibers onto the peripheral surface of a nip carrier roll comprising at least one of the mold roll and a pressure roll, the nip carrier roll carrying the fibers into the pressure zone to join the molten resin and secure individual fibers to the resin. In some examples, the nip carrier roll defines pillow cavities carrying a pillow of deposited loose fibers into the nip. The pillow of loose fibers substantially secures to the resin. The nip carrier roll may retain the deposited fibers on the peripheral surface of the roll by electro-static adhesion, a liquid, and/or a tacky substance until the deposited fibers engage the liquid resin. In some instances, the peripheral surface of the nip carrier roll defines undulations configured to hold fibers. The method may also include applying a vacuum to the peripheral surface of the nip carrier roll to carry the fibers. The nip carrier roll may selectively carry the deposited fibers on fiber retention regions defined by the roll that are surrounded by fiber-free regions of the peripheral surface of the nip carrier roll. The fiber retention region defines a pattern on the roll, in some instances, that is imparted to the liquid resin. 
         [0008]    In another aspect, a method of making a touch fastener includes introducing molten resin to a nip formed between a peripheral surface of a rotating mold roll and a peripheral surface of a rotating pressure roll, such that the resin at least partially fills an array of cavities defined in the rotating mold roll to form resin stems while a base of resin is formed interconnecting the stems. The method includes forming engageable heads on the stems and continuously applying a batt of fibers to at least one of the mold roll and the pressure roll, thereby exposing the batt of fibers to the molten resin during formation of the base and securing individual fibers of the batt to the resin. The method also includes substantially removing excess fibers from the base. The resulting base may advantageously achieve a coefficient of friction (MIU) of between about 0.125 and about 0.4, a frictional roughness (MMD) of between about 0.01 and about 0.2, and/or a geometrical roughness (SMD) of between about 1.5 μm and about 7.0 μm. In some implementations, after continuously applying a batt of fibers, the method includes substantially orienting (e.g. combing) the deposited fibers on the roll. 
         [0009]    In yet another aspect, a touch fastener includes an elongated resin base having upper and lower surfaces and a plurality of touch fastener elements extending from the upper surface. Individuals fibers are secured to a surface of the base and provide a base surface roughness of between about 1.5 μm and about 7.0 μm, a coefficient of friction of between about 0.125 and about 0.4, and a frictional roughness of between about 0.01 and about 0.2. 
         [0010]    The details of one or more implementations of the disclosure are set fourth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0011]      FIGS. 1-2  are schematic views of manufacturing processes forming touch fasteners including depositing fibers onto molten resin upstream of a forming nip. 
           [0012]      FIGS. 3-4  are schematic views of manufacturing processes for forming touch fasteners including depositing fibers onto at least one of a moll roll and a pressure roll. 
           [0013]      FIG. 5  is a schematic view of a manufacturing process for forming touch fasteners including continuously introducing a substrate to a forming nip. 
           [0014]      FIG. 6  is a schematic view of a manufacturing process for forming touch fasteners including continuously introducing a substrate to a forming nip and depositing fibers onto the substrate. 
           [0015]      FIG. 7  is a schematic view of a manufacturing process for forming touch fasteners including depositing fibers onto a carrier sheet, which carries the fibers into a forming nip. 
           [0016]      FIG. 8  is a schematic view of a manufacturing process for forming touch fasteners including continuously introducing a batt of fibers to a forming nip. 
           [0017]      FIG. 9  is a schematic view of a pressure roll defining fiber carrying cavities, as a portion of a manufacturing process for forming touch fasteners. 
           [0018]      FIG. 10  is a schematic view of a pressure roll defining fiber retention regions, as a portion of a manufacturing process for forming touch fasteners. 
           [0019]      FIG. 11  is a schematic view of a manufacturing process for forming touch fasteners including depositing fibers onto molten resin upstream of a forming nip. 
           [0020]      FIG. 12  is a side view, in partial cross-section, illustrating molten plastic extrusion into a forming nip between first and second coacting forming rollers. 
           [0021]      FIG. 13  is a side view of a touch fastener with an array of fastener elements and embedded fibers on a bottom base surface. 
           [0022]      FIG. 14  is a top view of the touch fastener of  FIG. 13 . 
           [0023]      FIG. 15  is a side view of a touch fastener with embedded fibers on a bottom base surface. 
           [0024]      FIG. 16  is a side view of a touch fastener with embedded fibers on top and bottom base surfaces. 
           [0025]      FIG. 17  is a top perspective view of a touch fastener with embedded fibers visible on a base of the touch fastener. 
           [0026]      FIG. 18  is a bottom perspective view of a touch fastener with embedded fibers visible on a base of the touch fastener. 
       
    
    
       [0027]    Like reference symbols in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0028]    Touch fastener components are used for personal care, industrial, consumer, and automotive applications, inter alia. In certain applications, the look and/or feel of the touch fastener component is an important factor. For example, in personal care applications (e.g. diapers), a touch fastener component having the look and feel of cloth or fabric is generally desirable. The comfort sensation of a fabric has many attributes and is generally described by a “fabric hand or handle”. Fabric hand is related to properties including flexibility, compressibility, elasticity, resilience, density, surface contour (e.g. roughness, smoothness), surface friction and thermal character. The drape of a fabric is an important aspect of fabric aesthetics and relates to the shape of the fabric while hanging down from its own weight. 
         [0029]    Fabric hand attributes can be determined subjectively (e.g., based on a person&#39;s experience and touch sensitivity) and objectively. One objective method of determining fabric hand attributes is the Kawabata Evaluation System for fabrics (KES-F). Characteristic values in the KES-F system include tensile, sheering, bending, compression, surface, weight, and thickness properties, each measured in both the warp and weft directions. An average value for each property may be obtained by averaging the measurements in the warp and weft directions. The surface properties include a coefficient of friction (MIU), frictional roughness (MMD), which is the mean deviation of MIU, and a geometrical or surface roughness (SMD). The coefficient of friction (MIU) and frictional roughness (MMD) values are 0 to 1 values, where a higher value corresponds to greater friction or roughness. Roughness is a measurement of the small-scale variations in the height of a physical surface, in contrast to large-scale variations, which may be part of the geometry of the surface. Geometrical roughness (SMD) is measured in microns, where a higher value corresponds to greater roughness. 
         [0030]    Referring to  FIGS. 1-4 , a method of making a touch fastener  10  includes continuously introducing molten resin  20  to a nip  30  formed adjacent a peripheral surface of a rotating mold roll  100 . In some implementations, the method includes continuously introducing molten resin  20  (e.g. via an extruder  25   a ) to a nip  30   a  formed between a peripheral surface of a rotating mold roll  100  and a peripheral surface of a rotating pressure roll  200 , as illustrated in  FIGS. 1-3 . In other implementations, the method includes continuously introducing molten resin  20  to the nip  30  from an extruder  25   b  to a nip  30   b  formed between a peripheral surface of a rotating mold roll  100  and a peripheral surface of the extruder  25   b,  as shown in  FIG. 4 . The process is similar to that described above, except only a mold roll  100  is used, i.e., no pressure roll  200  is necessary. Here, the extruder  25   b  is shaped to conform to the periphery of the mold roll  100  and the extruded resin  20  is introduced under pressure directly to the nip  30   b  formed between mold roll  100  and extruder  25   b.  The resin  20  at least partially fills an array of cavities  110  defined in the rotating mold roll  100  to form resin stems  40  while a base  50  of resin  20  is formed interconnecting the stems  40 . The molded fastener component  10  is stripped from the mold cavities  110  by a release roll  250 . Further details regarding this process are described in U.S. Pat. Nos. 4,794,028, 5,781,969, and 5,913,482, the entire contents of which are hereby incorporated by reference. 
         [0031]    Referring to  FIGS. 1-2 , in some implementations, the method includes adding loose fibers  60  (e.g., substantially separate, unattached, free floating fibers) to the molten resin  20  upstream of the nip  30 . The fibers  60  may be held in a hopper or bin  300  from which they are released and deposited onto the molten resin  20 . In some examples, the fibers  60  are released from the hopper  300   a  in random orientations or though a screen or aligner  302 , which orients the fibers  60  in a particular pattern for deposition onto the molten resin  20 . In other examples, the fibers  60  are blown onto the molten resin  20  with a fiber blower  300   b,  providing fiber deposition in random fiber orientations. Heat and pressure in the nip  30  secure individual fibers  60  to the resin base  50 . In some examples, the fibers  60  are made of a non-woven material. The fibers  60  may also include cotton or wood fiber, polyester, polyethylene, polypropylene, terephthalate, rayon, and/or blended fibers or multi-component fibers. 
         [0032]    Referring to  FIGS. 3-4 , in some implementations, the method includes continuously depositing loose fibers  60  onto at least one of the mold roll  100  and the pressure roll  200 , the roll  100 ,  200  carrying the fibers  60  into the nip  30 . In some examples, the loose fibers  60  are released from the hopper  300   a  in random orientations or though a screen or aligner  302 , which orients the fibers  60  in a particular pattern for deposition onto the roll  100 ,  200 . In other examples, the fibers  60  are blown onto the roll  100 ,  200  with a fiber blower  300   b,  providing fiber deposition in random fiber orientations. The fibers  60  are exposed to the molten resin  20  during formation of the base  50 . Heat and pressure in the nip  30  secure individual fibers  60  to resin base  50 . 
         [0033]    Referring to  FIGS. 5-6 , in some examples, the method further includes continuously introducing a flexible substrate  55  from a substrate roll  400  to the nip  30  such that the resin base  50  is laminated to the substrate  55  on the peripheral surface of the pressure roll  200 . Heat and pressure in the nip  30  (also referred to as a gap) laminate and bond the substrate  55  to the thermoplastic resin  20  while simultaneously forming the fastener stems  40 . The result can be a contiguous molded structure, without seams or weld lines, extending from the tips  42  of the fastener  10  into the substrate  55 , where the resin can intimately bond with features or fibers of the substrate  55  to form a strong, permanent bond. Further details regarding this process are described by Kennedy et al., U.S. Pat. No. 5,260,015, the disclosure of which is hereby incorporated in its entirety by reference. In some implementations, the fibers  60  are continuously deposited onto the substrate  55  which carries the fibers  60  into the nip  30 , as shown in  FIG. 6 , exposing the fibers  60  to the molten resin  20  during formation of the base  50 . The substrate  55  may have a tacky or retentive quality that retains the fibers  60  on the surface of the substrate  55 . Heat and pressure in the nip  30  secure individual fibers  60  to the resin base  50 . The resin  20  and/or the substrate  55  may be substantially transparent to accentuate a visual appearance of the embedded fibers  60 . 
         [0034]    In the example illustrated in  FIG. 7 , loose fibers  60  are continuously deposited onto a carrier sheet  57  which carries the fibers  60  into the nip  30 , exposing the fibers  60  to the molten resin  20  during formation of the base  50 . The loose fibers  60  may be deposited in a random or oriented manner. The carrier sheet  57  has a tacky or retentive quality that retains the fibers  60  on the surface of the carrier sheet  57 . In some examples, the carrier sheet  57  defines undulations or surface features that provide corresponding surface features on the molded base  50 . Heat and pressure in the nip  30  secure individual fibers  60  to the resin base  50 . The carrier sheet  57  is stripped from the molded base  50  after formation of the fastener component  10 . In some examples, the carrier sheet  57  is a continuous sheet trained about the pressure roll  200  and a carrier sheet/tape roll  410 . 
         [0035]    In the example illustrated in  FIG. 8 , the method includes continuously applying a batt of fibers  65  to at least one of the mold roll  100  and the pressure roll  200 , the roll  100 ,  200  carrying the batt  65  of fibers  60  into the nip  30 . In one example, the batt  65  of fibers  60  is a sheet of cotton. The batt  65  of fibers  60  is exposed to the molten resin  20  during formation of the base  50 . Heat and pressure in the nip  30  secure individual fibers  60  from the batt  65  of fibers  60  to the resin base  50 . Remaining excess fibers  60  from the batt  65  of fibers  60  are removed from the roll  100 ,  200  and the base  50  and can be subsequently reused. 
         [0036]    As illustrated in  FIG. 9 , the roll  100 ,  200  defines pillow cavities  210  that carry a pillow  66  of deposited loose fibers  60  into the nip  30 , such that the pillow  66  of loose fibers  60  is substantially secured to the resin  20 . In the example shown, the pressure roll  200  defines pillow cavities  210  that carry pillows  66  of loose fibers  60  deposited on the roll  200  into the nip  30 . 
         [0037]    Referring to  FIG. 10 , in some implementations, the deposited loose fibers  60  are retained on discrete fiber retention regions  205  of the peripheral surface of the mold roll  100  and/or pressure roll  200 . The retention regions  205  may be configured to define a pattern (e.g. plaid, checked, figures, etc.). In some instances, the deposited loose fibers  60  are retained on the peripheral surface of the mold roll  100  or pressure roll  200  by other retention means, such as electro-static adhesion, surface tension, a tacky substance, or vacuum pressure, for example. In the example of electro-static adhesion, a static charge is applied to the roll  100 ,  200  which then attracts and retains deposited fibers  60  on the peripheral surface of the roll  100 ,  200 . When a liquid is applied to the roll  100 ,  200 , surface tension of the liquid retains deposited fibers  60  on the peripheral surface of the roll  100 ,  200 . In the example of vacuum pressure, the roll  100 ,  200  defines vacuum paths  210  through or along its peripheral surface that are configured to retain deposited fibers  60  on the peripheral surface of the roll  100 ,  200 . The vacuum paths  210  are disposed in one or more of the fiber retention regions  205 . In some examples, the peripheral surface of the mold roll  100  and/or pressure roll  200  defines undulations  210  configured to carry the deposited loose fibers  60 . The undulations  210  may also be used to provide different surface characteristics of the base  50  (e.g. modified surface roughness, waviness, textured surface, embossing, etc). 
         [0038]    The method includes forming stems  40  on a base  50  of resin  20 . The resin  20  at least partially fills the array of cavities  110  defined in the rotating mold roll  100  to form resin stems  40  while a base  50  of resin  20  is formed interconnecting the stems  40 . The forming roller  100  and the pressure roller  200  are configured to permit relief of pressure at the laterally opposite sides of their interface so that the lateral flow of plastic material at the interface is unconfined. This arrangement has been found to provide added flexibility in practicing the present method since sufficient molten plastic material can be provided in the form of extrusion  20  to assure complete filling of the hook-forming cavities  110 , while at the same time excessive pressure is not created at the interface which could otherwise act to urge the rollers  100  and  200  away from each other. As will be appreciated, appropriate selection of the linear forming speeds of the fastener member  10 , as well as appropriate temperature control can avoid the need for providing pressure relief at the roller interface. In this regard, it will be observed in  FIG. 12  that an enlarged “bank” designated  21  is formed just upstream of the interface of the forming roller  100  and the pressure roller  200 . While it is desired that the bank  21  be of minimum dimension to avoid urging the rollers  100  and  200  apart, the creation of this bank assures the presence of an adequate supply of molten plastic material for complete filling of the hook-forming cavities  110 . Fibers  60  applied to one of the forming rolls  100 ,  200  meet the bank  21  of resin  20  as the particles  60  are carried into the nip  30 , where the fibers  60  become integral with the formed base  50 . Once transferred to the resin  20 , the fibers  60  are unrestrained in movement and flow. Consequently, the fibers  60  may mix with resin  20  and move in one or more directions (e.g., longitudinal and/or transverse directions with respect to a feed direction). 
         [0039]    In the examples illustrated in  FIGS. 8 and 11 , the method includes substantially removing excess fibers  60  from the base  50 . In one illustrated example, a brush  502  engages the back surface of base  50  to remove excess fibers  60 . The brush may be rotating against the motion of the stripper roll  250 , or stationary. In another example, a tacky roller  504  applied to the base  50  removes excess fibers  60 . Other examples of removing excess fibers  60  from the base  50  include applying and removing a tacky sheet, blowing air, washing, abrading or scraping the base  50 . In some implementations, the method includes substantially orienting the deposited fibers  60 , such as by combing the fibers upstream of the nip  30 , and in some cases after they are deposited on a substrate  55 , carrier sheet  57 , or roll  100 ,  200 . 
         [0040]    Referring again to  FIGS. 1-2 , the method includes forming engageable heads  44  on the stem tips  42  with a tip forming device  80 . In some examples, the tip forming device  80  includes a roller that flattens the stem tips  42  into engageable heads  44 . Referring again to  FIGS. 3-4  and  12 , in other examples, the entire fastener elements  45 , including engageable heads  44  on the tips  42  of stems  40 , are formed while in the nip  30 . The cavities  110  defined by the mold roll  100  are shaped to form stems  40  with engageable heads  44  on the tips  42  of stems  40 . Each hook projection  45  is provided with a configuration wherein the free end portion  42  of each projection  45  extends generally radially away from and generally toward the base portion  50  of the fastener  10 . It should further be noted that adjacent hook projections  45  face in generally opposite directions in a direction along the length of the fastener  10 . These features of the construction promote the desired interaction with the associated multi-loop fastener element, and assure the desired gripping or fastening action between the multi-hook fastener member and the multi-loop element. The engageable heads  44  flex or rotate about the stem during release from the mold roll  100 . In the example illustrated in  FIGS. 13-14 , engageable heads  44  of the touch fastener  10  are deformed (e.g. flattened) by a tip forming device  80  to form flat portion  46  on the engageable head  44 . 
         [0041]    Referring to  FIGS. 13-18 , a touch fastener  10   a,    10   b,    10   c,    10   d  (e.g. as resulting from the methods of manufacture described herein) includes an elongated resin base  50  having upper and lower surfaces  51  and  52 , respectively, and a plurality or array of touch fastener elements  45  extending from the upper surface  51 . Individual fibers  60  are secured to a surface  51 ,  52  of the base  50 , advantageously providing a coefficient of friction (MIU) of between about 0.125 and about 0.4, a frictional roughness (MMD) of between about 0.01 and about 0.2, and a geometrical roughness (SMD) of between about 1.5 μm and about 7.0 μm. The aforementioned ranges of surface properties for the base  50  objectively characterize hand with various degrees of cloth-like appearance and feel. In one preferred implementation, the resulting base  50  appears cloth-like, feels cloth-like, and has a coefficient of friction (MIU) of between about 0.145 and about 0.16, a frictional roughness (MMD) of between about 0.009 and about 0.015, and a geometrical roughness (SMD) of between about 4.3 μm and about 6.7 μm. In another preferred implementation, the resulting base  50  appears cloth-like, but does not necessity feel cloth-like, and has a coefficient of friction (MIU) of between about 0.1 and about 0.25, a frictional roughness (MMD) of between about 0.003 and about 0.02, and a geometrical roughness (SMD) of between about 1.5 μm and about 4.0 μm. This base  50  may feel relatively smooth (e.g. as with plastic tape). Providing a resin fastener  10  with a fabric hand substantial similar to cloth is advantageous to personal care implementations, inter alia. 
         [0042]    A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.