Patent Application
20070086682
The invention relates generally to reclosable fasteners and a method of forming a reclosable fastener profile assembly which allows for fast, automated production and accurate, seal registration. In particular, the invention relates to a seal arrangement for a reclosable zipper profile strip, which is created through the application of heat and pressure to a male and female profile to form a ‘compression molded segment’ seal, and to a method of producing such a seal.
The popularity of reclosable zipper fasteners has created a demand for a large number and wide variety of reclosable bag sizes and types. It is commonly known in the art to form a reclosable bag through the addition of a zipper profile to a pair of bag walls in order to form a bag with a reclosable, airtight seal. However, improper registration may cause the seal to weaken and fail over time or become permeable to the air. In many reclosable bag applications, an airtight seal is necessary to maintain the freshness of articles placed in the bag. Further, such seals must be suitable for high-speed automated production in order to make the production of reclosable bags commercially viable.
In the case of zipper profiles, commonly known methods of construction and seal formation often cause inaccurate, commercially unacceptable seals which cannot be produced on an economically practical scale. Commonly known profile formation methods in the art require multiple sealing devices, precise machinery or extensive retooling to alter the size and type of reclosable fastener. Exemplary devices are shown and described in U.S. Pat. No. 5,601,368 (Bodolay); U.S. Pat. No. 3,847,711 (Howard); U.S. Pat. No. 5,461,845 (Yeager); U.S. Pat. No. 5,823,933 (Yeager); U.S. Pat. No. 4,241,865 (Ferrell); U.S. Pat. No. 4,335,817 (Bahr); U.S. Pat. No. 4,909,017 (McMahon); and U.S. Pat. No. 5,024,537 (Tilman) and, in particular, U.S. Pat. No. 6,033,113 (Anderson). As such, none of the devices referenced above satisfy the need for a multi-purpose reclosable zipper profile, which can be accurately and economically manufactured using a minimum quantity of plastic material.
Therefore, an unfulfilled need remains for a zipper profile which can be accurately manufactured at a high rate of speed and which can be adapted to a wide range of reclosable zipper bag applications.
The present invention provides a reclosable fastener profile seal and a disclosed method of forming a fastener profile assembly. In particular, the preferred embodiment of the method of forming a fastener assembly includes a first profile strip, a second profile strip and a compression molded segment seal fusing the first and second profiles together to provide a reclosable faster having fused ends which form the opening for a reclosable bag. To manufacture the assembly, the first profile strip and second profile strip are fed by at least one motorized roller from a web or roll of respective profile strips. Interlocking ribs are included on the profiles to create an airtight reclosable seal which is suitable for a wide range of applications.
The present invention provides reclosable bags with air tight fasteners. Webster's Collegiate Dictionary, Tenth Edition, copyright 1997 by Merriam-Webster, Inc., defines “air tight” to mean “impermeable to air, or nearly so.” Under such as definition for “air tight,” those of ordinary skill in the art might construe an “air tight” seal on a plastic bag to mean a seal that is actually impermeable, or only nearly impermeable to air. Persons of ordinary skill in the packaging art construe an “air tight” reclosable seal to be defined by an industry standard air leak test known as ASTM D3078-02. Under this standard, a bag is submersed in water above which a pressure is applied. Leaks in the bags seal are manifested as air bubbles. As used herein, an “air tight” seal means a seal that will prohibit the transfer or movement of air molecules at atmospheric pressure and room temperature, across or through the seal structure for a substantially long time. In other words, an airtight seal should prohibit the transfer of air molecules from the inside to the outside and vice versa. For example, an “air tight” seal should be able to keep air molecules in a bag prior to the seal's closure and air molecules outside the bag after the seal's closure, for as long as the product contained within the bag is expected to be kept reasonably fresh.
The first and second profile strips are engaged to form a reclosable profile assembly. After the first and second profiles are interconnected, a portion of the first and second profile are sealed together. The interconnected first profile and second profiles are advanced and staggered applications of a compression molded segment seal are applied to the end portions of each profile assembly. This allows the profile assembly to be formed at a high rate with good accuracy. While being fused, the first and second profiles are cut to provide for individual reclosable fasteners.
In an alternative embodiment, the individual reclosable fastener profiles are not cut, thereby providing a continuous linear strip of fully formed reclosable bag profiles. In such an embodiment, the completed reclosable fasteners may be wound onto a roll for later separation and addition to bag walls.
It is a principal advantage of the invention to provide a reclosable fastener profile seal and method of forming a fastener profile assembly that can be produced quickly and precisely to form a zipper profile suitable for use in a wide range of reclosable bag applications.
It is another advantage of the invention to provide a reclosable profile assembly and a method of forming a reclosable fastener profile assembly, which is easily adjustable to provide a reclosable fastener profile of any commercially desirous length.
It is another advantage of the present invention to provide a reclosable profile assembly and a method of forming a reclosable fastener profile assembly, which is readily adaptable to seal and form reclosable fasteners and profiles of various sizes and styles.
It is yet another advantage of the invention to provide a reclosable profile assembly, which is suitable for attachment to a wide range of bag wall sizes and types.
Various other features and advantages of the invention are set forth in the following detailed description, drawings and claims.
While the specification and claims herein may refer to specific fastener or rib structures, it will be understood and fully appreciated that the principles of the present invention refer to closures generally and incorporate any compatible closure type or style. As such, before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of the construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
As seen in
The profile assembly 10 includes a first profile 14. The first profile 14 is flat, thin piece of packaging material preferably manufactured from polyethylene. As most clearly depicted in
The second profile 18 is preferably manufactured from the same material and with the same dimensions as the first profile 14. As best depicted in
As seen in
In the preferred embodiment of the present invention, the “mold” is a die and anvil. Heat and pressure applied to the seal material causes the seal material to liquefy. When it liquefies, it flows into voids between the two film layers. The sealed areas are gradually cooled, causing the material in the mold to cool and solidify, taking the shape of the mold. In a preferred embodiment of the invention, the cooling time in the mold is increased and the amount of heat is reduced in order to cure the finished product more slowly. In so doing, the segment seal 22 retains its cross section better than it would if the mold were opened quickly or at a relatively higher temperature, and gaps between the film layers which would otherwise allow the passage of air across the seal, are eliminated.
The compression molded segment seal 22 of
The formation of the profile assembly 10 and compression molded segment seal 22, as depicted in
As seen in
As seen in
As seen in
Alternatively, as seen in
As indicated in the first full paragraph on page 6 of the Ser. No. 09/415,696 application as filed, parent of the present application, the compression molded segment seal 22 of
The formation of the profile assembly 10 and compression molded segment seal 22, as depicted in
As seen in
As noted in U.S. Pat. No. 7,041,249, which is one of the parents of the present application, in regard to avoiding distortion, Col. 8, lines 37-51
Thus avoiding distortion of the fastener profiles during manufacture is one of the principal objectives and advantages of the present invention.
As seen in
Reclosable portion 120 includes first backing 122 and troughs 124, which typically extends lengthwise along fastener strip 100. Reclosable portion 120 also includes second backing 126 and ridges 128 for mating with troughs 124 in an airtight, reclosable seal that essentially prevents air flow from one side of the seal to the other. Flap or flange 127 conveniently extends from second back 122 to an exterior side of fastener 100 in order to protect trough 124 and ridge 128 from damage and to facilitate a user's grip for opening fastener strip 100.
The relative positions of troughs 124 and ridges 128 are depicted in
Commonly, the thickness of planar portion 140 is about the thickness of one of the backings 122, 124 to about the combined thickness of both of the backings. Planar portion 140 is essentially free of mating ridges and troughs, such as trough 124 and ridge 128, and includes essentially no void spaces.
Plug 160 joins troughs 124 and ridges 128 in an airtight seal at adjacent end 130 of reclosable portion 120. Troughs 124 and ridges 128 define longitudinal interstitial voids (best seen in
Dam 180 joins plug 160 to first backing 122 and to second backing 126 as depicted in
The relationship of plug 160 to dam 180 is best seen in
Inspection of
The view in
Turning now to
Longitudinal interstitial voids commonly exist between trough 124 and ridge 128. While the voids do not necessarily interfere with the airtight seal between the sides of fastener strip 100, the voids permit air flow longitudinally along trough 124 and ridge 128. Fastener strip 10 is composed of a material that becomes progressively more fluid with increasing temperature, hereinafter referred to as a “thermoplastic” material.
Vibrator 220, illustrated in
Horn 233 is also known as a solid resonator, a concentrator, or a mechanical amplifier. Horn 233 is dimensioned to be resonant at a predetermined frequency of vibration. When horn 233 is energized at its proximal input surface by an actuator 231, it provides ultrasonic energy (vibrations) at its opposite distal end to a workpiece that is in forced contact with the distal end.
As depicted in
Details of first matrix 240 are presented in
During use, first matrix 240 is placed over fastener strip 10, with groove axis 252, trough 24 and ridge 28 generally aligned. Moveable anvil 230 includes a generally planar face 23 that supports fastener strip 10 from below. Alternatively, fastener strip 10 may be placed between two vibrators 220 (not shown) for vibrating and pressing between two first matrices 240 (not shown).
Vibrator 220 vibrates a portion of fastener strip 10 so as to generate internal friction within fastener strip 10, causing a portion 212 of fastener strip to become relatively more malleable. The temperature of the vibrated portion often increases during the vibrating. The pressure exerted by first matrix 240 tends to displace some of the malleable portion in predictable directions. For example, the depth of transition volumes 251, 253 and the depth of groove 252 are calculated to displace a certain amount of the malleable portion along groove 252, and displace a certain amount of the malleable portion to or from the transition volumes 251, 253. Malleable material is also displaced transversely from the groove axis as first matrix 240 flattens the region between cutouts 248, 250.
First matrix 240 is properly shaped to press and extrude the displaced material in desired directions and, also, to mold and retain the displaced material at desired destinations. Preferably, the material displaced by first matrix 240 forms plug 160 or dam 180 of fastener strip 100 of the present invention; most preferably plug 160. The result is a product having first shape 242, depicted in
Turning now to
As with first stage 256, the temperature, pressure, time and distance between die faces 266, 286, 306 and respectively associated anvils are carefully controlled. The optimum combination of these factors depends on the precise nature of the fastener strip and the specifications of the finished seal portion. However, die temperatures of about 350 to about 400 degrees F. and pressures of about 60 to about 80 pounds per square inch have been employed successfully in pressing stages 276, 296, 316 with a pressing time of about half a second. Fifth stage 320 cools the finished product, which is fastener strip 100. Also shown in
Overall flatness of the finished fastener strip, such as fastener strip 100, is an important requirement for many fastening applications. Third stage 296 works with die 284 to generally flatten backings 122, 126 of fastener strip 100 and ensure that reclosable portion 120 and planar portion 140 are coplanar. Face 286 defines longitudinal channel 284, which is significantly deeper and wider than groove 252. Accordingly, die 284 has relatively little effect on plug 160 or dam 180. Third stage 296 produces third shape 282, which is similar to the shape of fastening strip 100. Again, a stripper plate 284A is utilized to facilitate separation after compression.
Die 304 has a generally planar face 306 with cutouts 308, 310 and is similar to die 262, except that cutouts 308, 310 are positioned closer together and have greater radii than cutouts 268, 270. When pressed against third shape 282 under proper conditions of pressure, temperature and spacing, die 304 completes planar portion 140 and produces fourth shape 302, which is the shape of fastener strip 100. Fifth stage 316 cools fastener strip 100 so that it may be more conveniently transported and packaged. Again, a stripper plate 304A is utilized to facilitate separation. After the shaping of fastener strip 100 is completed, conveyor belt 321 advances the fastener strip to a second conveyor 101. As it cools, fastener strip 100 no longer adheres to belt 100, so it can be removed without stretching or distortion. The lack of tension on fastener strip 100 is crucial to maintaining the dimensions and configuration of the fastener strip 100. Fastener strip 100 is then advanced by second conveyor 101 to a take up reel 103, again maintaining minimum tension and compression of the fastener strip 100.
The invention also provides a method for sealing portions of a thermoplastic fastener strip, which process will now be described. The invention is not limited to the described process, starting materials, equipment or products.
A fastener strip, such as fastener strip 10 is the starting material. A tensioning assembly, such as a dancer roller assembly, is suitable for tensioning fastener strip 10. Dancer roller assembly 216 applies a precise tension to fastener strip 100, as will be appreciated and understood by practitioners. Fastener 100 is preheated by preheaters to a temperature warmer than room temperature and cooler the melting point or index of the thermoplastic material that composes fastener strip 100. For example, a temperature in the range of about 120° to about 130 degrees F. is often useful. Control of temperature and tension prevents distortion of the fastener strip 100. Fastener strip 100 is then advanced by conveyor belt 321.
A portion of fastener strip 100 is vibrated between a vibrator and an anvil at a first stage 200. The vibrating is effective to increase the malleability of the portion, as compared to the malleability of fastener strip 100 before vibrating. A first matrix 240 is pressed against the malleable portion to produce a first shape. The pressing may be carried out simultaneously with the vibrating. Second matrix 260, third and fourth matrices 280 and 300 are subsequently pressed against the malleable portion to produce a second shape, a third shape and a fourth shape, respectively. Each pressing is accomplished in a separate stage at a different location. The fastener strip may be heated before or during the stages. The finished fastener strip is cooled to room temperature and may then be wound on a spindle or roll for later use by the bag converter, again at a precise tension to avoid distortion.
The vibrator oscillates in contact with the fastener strip at a frequency of about 10,000 to about 100,000 cycles per second, preferably at least about 20,000 cycles per second. As described above, the vibrator includes an actuator, a resonator or horn, and a first matrix, which is unitary with the horn. The vibrator is positioned over the fastener strip and an anvil is positioned under and in contact with the fastener strip. Preferably, the vibrator does not touch the anvil. Alternatively, two or more vibrators may be brought in to contact with the fastener strip with the fastener strip positioned between the vibrators.
Applicant respectfully submits that one of ordinary skill in the art at the time of the invention would know precisely what the term “compression molding” means, and the appropriate parameters for compression molding. In Modern Plastics Encyclopedia dated October, 1991, on page 271-272, is a complete description of compression molding.
In the preferred embodiment of the present invention, the “mold” is a die and anvil. Heat and pressure applied to the seal material causes the seal material to liquefy. When it liquefies, it flows into voids between the two film layers. The sealed areas are gradually cooled, causing the material in the mold to cool and solidify, taking the shape of the mold. In a preferred embodiment of the invention, pressure is increased, the cooling time in the mold is increased and the amount of heat is reduced in order to cure the finished product more slowly. In so doing, the segment seal 22 retains its cross section better than it would if the mold were opened quickly or at a relatively higher temperature and gaps between the film layers which would otherwise allow the passage of air across the seal, are eliminated. The aforesaid process is referred to herein as compression molding.
As seen in Modern Plastics Encyclopedia, 1991, pages 609-618, compression molding machines were widely known as early as 1991. The pressures of 1,000-2,000 psi and 300-400° are described in the Modern Plastics Encyclopedia, page 272. In the present case, in order to avoid deformation of the fastener profiles, as claimed, temperature was reduced and pressure was greater than in comparison with conventional heat sealing methods for sealing fastener profiles such as Anderson U.S. Pat. No. 6,033,113.
In regard to the patent of Anderson '113, the claims include the limitations that the first and second profile strips are substantially flat but have, in the case of the first profile strip, at least one rib extending therefrom without further filling material or plastic and similarly in the case of the second profile strip. The compression molded segment seal portion is formed by fusing the first profile strip and the second profile strip and the ribs of the first and second profile strips through the application of heat and pressure without further filling material or plastic, unlike Anderson. The fused section is substantially flattened to form an air-tight seal of first and second profile strips, less than the combined thickness of the first and second profile strip, as disclosed in the original application. The claims of the present invention are limited to “without further filling material or plastic.” The patent of Anderson requires use of a fillet, either formed integrally of the fastener strip, or provided as additional material in order to seal the ends of the fastener strips together. Thus, unlike Anderson, the ends of the first and second profile strips are sealed to each other to form an airtight seal “without further filling material or plastic.” The advantages in terms of reduction of plastic usage, easier sealing of the ends of the fastener strips without bumps or bulges of additional plastic, and a simpler profile strip to initially manufacture are obvious.
Various features and advantages of the invention are set forth in the following claims.
This is a continuation-in-part of U.S. patent application Ser. No. 09/415,696, which was filed on Oct. 12, 1999, and a continuation-in-part of U.S. patent application Ser. No. 10/831,989 filed Apr. 26, 2004, which is a continuation-in-part of U.S. application Ser. No. 10/337,139, now U.S. Pat. No. 7,041,249, which was filed on Jan. 7, 2003, and also a continuation-in-part of U.S. Ser. No. 10/430,247, now U.S. Pat. No. 7,074,359.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 09415696 | Oct 1999 | US |
| Child | 11555451 | Nov 2006 | US |
| Parent | 10831989 | Apr 2004 | US |
| Child | 11555451 | Nov 2006 | US |
| Parent | 10337139 | Jan 2003 | US |
| Child | 11555451 | Nov 2006 | US |
| Parent | 10430247 | May 2003 | US |
| Child | 11555451 | Nov 2006 | US |
