Stock material or miscellaneous articles – Structurally defined web or sheet – Including fastener for attaching to external surface
Reexamination Certificate
1999-06-30
2001-09-11
Silbaugh, Jan H. (Department: 1732)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including fastener for attaching to external surface
C264S167000, C264S210200, C425S175000, C425S362000, C024S452000
Reexamination Certificate
active
06287665
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and a device for manufacture of a hook-and-pile type fastener with a multiplicity of interlocking means or elements designed as one piece with a backing and in the form of stalks with enlarged areas. A thermoplastic in the plastic or liquid state is introduced into the gap between a pressure roller and a shaping roller. The shaping roller is provided with outward and inward openings. Both rollers are propelled in opposite directions, so that the backing is formed in the gap between the rollers.
BACKGROUND OF THE INVENTION
A process for manufacturing hook-and-pile type fasteners is disclosed in WO 94/23 610 of the Minnesota Mining and Manufacturing Company. In this process, as also in the manufacturing process disclosed in U.S. Pat. No. 3,270,408, first pinshaped bodies are produced whose ends are reshaped into mushrooms in a second operating cycle. Mushroom heads with parts of the head flattened are disclosed in U.S. Pat. No. 3,196,490. The formation of a hook-and-pile fastener, for baby diapers or for hospital clothing in particular, is disclosed as a potential application for fastener elements produced in this manner.
A relatively large number of interlocking means per square centimeter are required in order for the hook-and-pile fastener elements to be used as fasteners for these types of clothing articles. This results in high costs for the shaping roller employed in the state of the art to shape the interlocking means. In manufacture of this shaping roller, it is necessary first to imprint at considerable expense a number of openings corresponding to the number of interlocking means. In addition, a vacuum device must be integrated to perform the function of orienting the stalks of the recesses. The shaping roller must be cooled to a specific temperature during operation. A second process step is required, in addition to production of the stalks, to form mushroom heads on the oriented stalks by contact with a heated roller.
Another disadvantage of the conventional process is due to the fact that the location of the extruder head containing the thermoplastic must be adjusted with very high precision. The extruder head must be opposite the shaping roller to obtain a flat backing of very slight thickness, as required, for example, for use in fasteners in baby diapers. For example, every repeated charging of the extruder head may result in maladjustment of the extruder head relative to the shaping roller, causing interruptions of production.
WO-A-94/29070 describes a shaping tool using a laser for the manufacture of plastic elements which can incorporate shaping of their surface. The shape is obtained by openings forming blind holes in a flat or circular cylindrical substrate. The shaping occurs as a result of the pressing of a pressure stamp on the shaping substrate. The shaped elements can be further modified in their shape by suitable subsequent processing steps following the shaping.
U.S. Pat. No. 3,399,425 describes a device for shaping of material surfaces, and among other things, for the shaping of interlocking means in the form of stalks projecting from a backing tapering conically, and on the end more distant from the backing being wrinkled or crimped. For this, the device is made up of a pressure roller and a shaping roller incorporating a screen with outwardly and inwardly conically tapering openings. The interior surface of the shaping roller is acted upon with a low pressure, as compared with the exterior surface, and can be cooled.
SUMMARY OF THE INVENTION
Objects of the present invention are to provide a less costly and more cost effective method for manufacture of hook-and-pile fastening elements of thermoplastic, the device or apparatus required for this purpose, and fastening elements or fasteners produced by this method.
The foregoing objects are basically obtained by a method for manufacturing a hook-and-pile fastening element having a plurality of interlocking elements formed integrally with a backing. The method comprises introducing thermoplastic in a plastic or liquid state into a gap between a pressure roller and a shaping roller, while rotating the pressure roller and the shaping roller in opposite directions. The shaping roller has a screen with outward and inward electroplated, etched or laser formed cylindrical openings. The backing is formed in the gap between the rollers. The thermoplastic is hardened, at least to some extent, in the openings in the screen of the shaping roller to form finished interlocking elements, having stalks with enlarged areas configured as mushroom heads extending radially from the stalks, exclusively from the hardening of the thermoplastic in the openings.
The foregoing objects are also basically obtained by an apparatus for manufacturing a hook-and-pile fastening element having a plurality of interlocking elements formed integrally with a backing. The apparatus comprises a shaping roller having a screen with outward and inward electroplated, etched or laser formed cylindrical openings. The openings have radially enlarged areas at inner and outer ends thereof. A pressure roller is spaced a distance from the shaping roller defining a gap therebetween. The shaping roller and the pressure roller rotate in opposite directions. A feed mechanism delivers thermoplastic in a plastic or liquid state into the gap. The thermoplastic forms the backing in the gap and exclusively forms the interlocking elements by hardening, at least to some extent, in the openings to form finished interlocking means having stalks with mushroom heads extending radially from the stalks and formed in the enlarged areas.
Since the shaping roller has a screen whose recesses or openings are produced by etching, electroplating, or a laser, it is possible rapidly to produce a suitable screen for the shaping roller for varying number of fastenings means for square centimeter. The number interlocking means formed is determined by the mask of the screen. Screens are used in the method process which are more or less known from the printing industry.
The openings formed by etching, electroplating, or by means of a laser can have radii extending inward at regular intervals on their perimeters. During filling of the inward and outward openings, stalks are automatically formed by these radii, which stalks already have enlarged areas in the form of disks. This eliminates the need for a second operation in which the stalks are provided in conventional methods with enlarged areas in downstream processing. Costly cooking of the shaping roller is also eliminated, since fastening elements of thermoplastic are removed from the shaping roller once the plastic has hardened at least to some extent.
The method of the present invention can be carried out more or less with any thermoplastic. Preferably, polypropylene, polyamide and polyethylene are used, depending on the application. Terpolymers containing one or more of the thermoplastics named are also suitable.
Another advantage of the method of the present invention is that the enlarged areas on the stalks can be made in widely varying forms at low cost. For example, the enlarged areas can be designed as mushrooms having flattened or concave openings, or they may be in the form of polyhedra ranging from triangles to hexagons. In addition, the triangular to hexagonal enlarged areas may have rounded comers, this increasing the possibility of interlocking.
Preferably, the fastening elements are manufactured with a backing thickness of 0.05 to 0.5 mm and a number of interlocking means of the order of magnitude of 50 to 400 interlocking means per square centimeter. It is also theoretically possible to prepare backings which are thicker and are provided with a smaller or larger number of interlocking means.
In one embodiment of the present invention, the backing is 0.05 to 0.3 mm, preferably 0.1 to 0.2 mm, thick and is provided with 200 to 400, preferably 300, interlocking means per square centimeter. Fastening elements produced in this manner are used preferably fo
Eashoo Mark
Gottlieb Binder GmbH & Co.
Roylance Abrams Berdo & Goodman L.L.P.
Silbaugh Jan H.
LandOfFree
Method and device for producing a hook-and-pile type closure... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for producing a hook-and-pile type closure..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for producing a hook-and-pile type closure... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2541351