NZ210765A - Forming integral interlocking closure film stock - Google Patents

Description

2 10765 Priority Date(s): ?.l.. •. A Complete Specification Filed: ?£ aass-8r*?j>y'/e?..

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NEW ZEALAND PATENTS ACT, J 953 No.: Date: COMPLETE SPECIFICATION PROCESS AND APPARATUS FOR FORMING INTEGRAL INTERLOCKING CLOSURE FILM STOCK I/We,, UNION CARBIDE CORPORATION OF Old Ridgebury Road, Danbury, State of Connecticut, 06817, U.S.A., organized and existing under the laws of the State of New York, UNITED STATES OF AMERICA hereby declare the invention for which I / we pray that a patent may be granted to me/us, and the method by which it is to be performed, to be particularly described in and by the following statement:- - 1 - (followed by page -la-) 210765 PROCESS AND APPARATUS FOR PORMIWG INTEGRAL INTERLOCKING CLOSURE FILM STOCK This invention relates to plastics (hereinafter "plastic") containers having an interlocking closure fastening device, and more particularly, to a process and apparatus for making stock material to be used in the production of interlocking closure bag articles. fasteners are generally well known and widely used by consumers and in industry. Their popular use has provided a strong incentive for the development of improved manufacturing equipment and methods for more economical operations, as well as products having more appeal in the marketplace.

One particularly desirable type of reclosable fastener is disclosed in NZ Patent Specification No. 190058 wherein the closure fastening device comprises a first channel element including a base portion, a pair of spaced apart webs extending from the base portion, and hook portions extending from each of the webs and facing away from each other. A second channel element includes a base portion, a pair of spaced apart webs extending from the base portion, and hook portions extending from each of the webs and facing towards each other. The channel elements interlock by pressing the first channel element into the second channel element 60 that the hook portions engage each other. This closure fastening device is attached in the an Description of the Prior Art Plastic containers which feature reclosable © 2L0765 the container opening to form a container capable of being closed and opened.

Generally, the plastic container stock i6 made from a film of polyethylene, polypropylene, nylon or other thermoplastic naterial which 1e manufactured by extrusion. Each closure element of the fastening device can be manufactured as a strip for subsequent attachment to the film by the use of appropriate means. For example, a thermoelectric device can be used to apply heat to a film in contact with a closure strip to cause a transfer of heat through the film to produce fusing at the interface of the film and the closure 6trip. The fusing of the film and the closure strip may also be established by the use of hot melt adhesives. hot air sealing, or other methods such as ultrasonic heating. However, hot air sealing of closure Btrips to a film requires a sizable inside closure flange to seal to the film. Thi6 extra material in the closure 6trip6 contributes little to functionality of the container and increases its cost. Further, the resulting hot air seals do not cover the entire flange of each closure strip thereby making the flanges noticeably visible and giving the reclosable container an added-on appearance.

To avoid the aforementioned detractions, it has been proposed to adhere the closure fastening device integral with the film as disclosed in NZ Patent Specification No- 196471. It is taught therein that the production of a plastic film connected to a pair of occludable closure strips may be provided by feeding a supply of pre-formed closure 6trips onto a casting OCT 1986 . # A; O © W 2 10 7 6 5 cylinder and extruding a molten plastic fila onto the casting cylinder with the closure strips so that the plastic film, before cooling, becomes fused to the flange portions of the closure strips. The casting cylinder is provided with a pair of 6paced-apart circumferential grooves so that the respective profile portions of the closure strips extend therein. During casting of the molten plastic film, urging means are employed for pressing the plastic film against the flange portions of the closure 6trips. The molten slot cast film is susceptible to being thinned out in the area directly adjacent to the lamination thereby giving rise to weak areas along the closure strip flange edges.

Thus, it would be desirable to avoid the aforementioned disadvantages with the prior art, reduce overall capital equipment expenditures by eliminating the need for separate closure strip production lines, and also production plant floor space requirements. Such would also reduce operating expenses by eliminating labor cost6 associated with closure Etrip production lines. lower raw material costs by avoiding closure strip production line waste products, and eliminate closure strip inventory requiring warehouse 6torage facilities. Further, the male and female closure halves would be subjected to less mechanical working.

It has further been proposed to avoid the aforementioned disadvantages with the prior art, as disclosed in U.S. Patent 4,263,079, by forming an integral thermoplastic fastening means on a cast thermoplastic film. It is therein disclosed that an 0 P 13993 .3, integral closure neans is provided by extruding fastener elements angularly disposed towards a cast film, joining the fastener element^ and the film, and cooling the fastener elements and the film upon 5 a chill roll. However, the joining of the fastener elements and the film muBt occur at a point closer to the film die lips than to the chill roll, and in order to obtain satisfactory adhesion between the fastener elements and the film, the edge of the 10 profile die plate must be located below and toward the film surface with respect to the exit of the film die. Water jets are aligned with the fastener elements to cool them, and a second water jet may be located on the opposite 6ide of the chill roll for 15 further cooling of the fasteners.

The apparatus for practicing the aforementioned method is claimed in U.S. Patents 4.29S.919 and 4.3SB.334. It is therein recited that the apparatus comprises a film extrusion die having 20 an extrusion channel ending in die lips which present a surface defining a plane, and wherein a 6ide of the die presents a face angularly disposed towards the extrusion channel and the die lips. A fastener extrusion die block is located adjacent the 25 aforementioned film die face with a fastener extrusion die plate secured thereto. The fastener die plate has a leading edge located out of the plane of the film die lips. The fastener die block has an extrusion channel disposed angularly adjacent 30 its exit to increase the acuteness of the angularity of the extrudate issuing from the die plate vith respect to the extrudate issuing from the film die D- 13M2 1 lip6. Cooling means are located below the extrusion die and die plate. The apparatus includes cooling means that cause water to impinge upon the joined fastening means and film, means for passing the 5 joined combination around a roller wherein the part of the roller receiving the combination being the combination receiving side, and the part of the roller from which the combination leaves being the combination take-away side, an air jet apparatus 10 having a nozzle located closely adjacent the take-away side of the roller, and a tongue extending from the air jet apparatus beyond the nozzle to direct air from the nozzle along the joined combination to remove excess water therefrom. 15 However, it would be desirable to provide a method and apparatus for forming integral interlocking closure and film stock material wherein the fastener element extrusion die block need not be secured to the film die in a fixed position so that 20 placement of a fastener element extrudate onto a film could be more readily modified. In addition, a fastener die block having an extrusion channel disposed angularly to increase the acutenesE of the angularity of the extrudate with respect to the 25 extrudate issuing from the film die lip6 may cause deformation of the fastener means or the film when they contact each other. Further deformation of the integral interlocking closure stock may occur wherein a chill roll is located so that one of its 30 lateral extents extends to the die plate side of the die lips, thereby angularly disposing the extrudate 2 10765 from the film die lip6 toward the extrudate issuing from the fastener die plate.

Thus, there is a continuing need for a method and apparatus to provide integral 5 interlocking closure film &tock material which overcomes the above-noted problems.

Suffimary of the Invention In accordance with this invention, generally speaking, there is provided a method of r,... 10 forming integral interlocking closure film 6tock material comprising feeding a supply of molten thermoplastic material to a slot extrusion die. extruding said molten thermoplastic material from said 61ot extrusion die onto the periphery of a 15 casting roll to form a film of said thermoplastic material, feeding a supply of molten thermoplastic material to interlocking closure profile dies, extruding said molten thermoplastic material from 6aid profile dieB 60 that the formed interlocking 20 closure elements immediately contact and adhere to said film of thermoplastic material to form an integral closure web at a location between about one to five inches prior to the tangency point of said web with the periphery of 6aid casting roll. 25 partially cooling said closure elements by directing a primary controlled flow of water onto the surface of 6aid closure elements to stabilize the shape of the closure elements, impinging a flow of air on the film portion of said web at approximately the 30 tangency point of said web and the periphery of said casting roll, and further cooling said closure elements by feeding secondary cont'oiled streams of P\\A# 21 % 210 76 5 water directly onto said closure elements. Positioned downstream from the location of the secondary cooling water streams are water stripping neans comprising one or more water suction nozzles 5 and air nozzles to remove water from the integral interlocking closure stock material. The integral interlocking closure stock material is then passed over a chill roll, slit, passed through a nip, and thereafter folded by one or more folding devices. 10 In another embodiment of this invention, there i6 provided an apparatus for producing integral interlocking closure film stock material comprising a film 6lot ca6t extrusion die. a plurality of closure profile dies positioned 15 downstream of said film extrusion die exit and arranged so that the molten thermoplastic material from said profile dies exits between about one inch and about five inches after the exit point of the molten thermoplastic material from said film 20 extrusion die. a casting roll positioned downstream of said film extrusion die exit and 6aid profile dies to receive and cool a film of molten thermoplastic material exiting from 6aid film extrusion die at a distance between about three o 25 inches and about eight inches after the exit of said film slot extrusion die and at a distance between about one inch and about five inches after the exits of said cloEure profile dies. Primary cooling nozzles for partially cooling the closure elements ^ 30 are positioned such that coolant first contacts the closure elements at a distance less than about one inch after the exits of the closure profile dies. 210765 The primary cooling nozzles direct a controlled flow of water onto the surface of the molten closure elements. In thi& node, the primary cooling nozzles initiate cooling of the closure elements even before 5 the tangency point of the fused closure elements and slot cast film on the periphery of the casting v.-' roll. An air knife i6 positioned opposite from and facing the casting roll, at about the tangency point of the slot ca6t film and the periphery of the 10 caEting roll, to impinge air on the film. The air /**) knife is employed to improve cooling of the slot caBt film as the film travels with the rotating casting roll. Downstream from the air knife are secondary cooling nozzle assemblies to effect 15 further cooling of the closure elements. The areas about the exits of the secondary cooling nozzles are confined to provide a region through which the profile portion of each of the closure elements can travel without damage. Each of the cooling nozzles 20 is provided with a controlled supply of water.

Interspersed with the secondary cooling nozzles, in the direction of web travel, are suction segments which serve to withdraw some of the spent cooling water to improve the cooling efficiency in the areas ^ 25 around the closure elements. Downstream from the secondary cooling nozzle assemblies are one or more water suction nozzles, and downstream therefrom are positioned one or more air nozzles. The one or more water suction nozzles are located close to the one 30 or more air nozzles to minimize "fan-out" of the cooling water as it is removed from the area around the cooled closure elements. One or more chill 9 - 2 10765 rollG. also positioned downstream of the air knife, serve to provide further cooling of the integral' interlocking closure stock material. Just prior to passing over the last chill roll, which may form a 5 nip with another roll, the web may be slit, as with _ edge trim. After leaving the last chill roll, the web(s) is folded by a folding device(s) and then occluded prior to being processed further.

Brief Description of the Drawings Fig. 1 i6 a schematic elevational view depicting an equipment arrangement for integrally forming closure elements on film or sheet in accordance with this invent ion; 15 Fig- 2 i6 an enlarged close-up schematic elevational view of the film 6lot die. a profile die. some of the primary closure cooling nozzles, the air knife, a secondary cooling nozzle assembly, and their relationship with respect to each other 20 and the casting roll as depicted as part of the equipment arrangement illustrated in Fig. 1: Fig. 3 is a greatly enlarged perspective view of the exit face of one of the closure profile dies depicting an adhesion slot; and 25 Fig. 4 is a greatly enlarged perspective O view of one portion of the secondary cooling nozzle assembly illustrating a confining channel therein and one or more openings for directing cooling water at one of the closure elements and adjacent areas.

Detailed Description of the Invention In greater detail, integral interlocking closure film 6tock material is provided in <HT~ 2107 accordance with thi6 invention by feeding a supply of nolten thermoplastic material from a conventional screw extruder (not shown) to a 6lot extrusion die 10 generally illustrated in Fig. 1. Slot extrusion 5 die 10 ha6 a generally elongated opening extending parallel with, and spaced from, the periphery of a casting cylinder 11. wherein 6lot extruBion die lo is capable of casting a film or 6heet 12 of molten thermoplastic material on the periphery of rotatable 10 casting cylinder 11. Casting cylinder 11 i6 provided with neanE (not shown) for rotating the casting cylinder at a controlled rate of rotation. A plurality of closure element profile die6 13 (one shown) are fed a supply of molten thermoplastic 15 material from a conventional screw extruder (not shown). As each formed closure element exits from profile dies 13. it swells in an amount sufficient to contact and adhere to film 12 exiting from 6lot extrusion die 10. After contact of the formed 20 closure elements with film 12. and adhesion therewith, the closure elements are partially cooled by directing a controlled flow of water onto the surfaces thereof from primary cooling nozzles 14 and 14' (only two of which are 6hown). Partial cooling 25 of the closure elements serves to stabilize their 6hape. It has been found that if the shape of the cloBure elements is not stabilized properly, the closure elements will continue to be drawn-down excessively and thus altered. The formed closure 30 elements may exit from profile dies 13 at any desired transverse location onto film 12, but preferably, the profile dies 13 are positioned so '/to 2 1 0 7 & s that the formed closure elements contact fila 12 near the outermost lateral portions of film 12. In any event, the formed closure elements are in spaced parallel relation to each other on film 12. In 5 operation, primary cooling nozzles 14 and 14* are precisely positioned by attachment to positioners IS (one 6hown) so as not to damage the molten closure elements. As shown in Fig. 1. and in greater detail in Fig. 2. the primary cooling nozzles 14 and 14' 10 (only two are 6hown for clarity), the positioners lb (one shown in Fig. 1). and the closure element profile die6 13 (one shown) are actually mounted (not shown) from a part of 6lot extrusion die 10 for accurate placement in accordance with the foregoing 15 requirements. The primary cooling nozzles 14 and 14'. the positioners 15. and the profile dies 13 can all be easily repositioned at other lateral positions on die 10. Downstream from primary cooling nozzles 14 and 14' i6 positioned an air 20 knife 16 opposite to casting cylinder 11 for impinging air on integral closure web 20 at about the tangency line of integral closure web 20 on the periphery of casting cylinder 11. Air knife 16 is used to improve cooling of the film portion of 25 integral closure web 20 as it travels with rotating casting cylinder 11. The direction of the air stream from air knife 16 is controlled such as to prevent flutter of integral closure web 20 which may adversely affect adhesion of the molten closure 30 elements to film 12. In this regard, the direction of the air 6tream from air knife 16 may be at an angle of between about 5 degrees and about 60 2 t C degrees, but i6 preferably at an angle of about 30 degrees, downward from the horizontal plane.

Another consideration in employing air knife 16 is the selective internal or external blockage or diversion of air flow away from the partially cooled closure elements to avoid deformation thereof. In addition, integral closure web 20 edge constraining means (not shown) are preferably used in combination with air knife 16 to stabilize the flatwidth of integral closure web 20. and hence the relative positions of the closure elements at lateral points on integral closure web 20.

Further cooling of the closure elements is provided by passing the closure elements through a secondary cooling nozzle assembly (one shown) 17 located at each closure element position. Secondary cooling nozzle a66embly 17 is configured to enable travel of each of the closure elements through a coolant confining region, as shown in greater detail in Fig. 4. Each portion of the secondary cooling nozzle assembly 17 is constructed 6uch that each portion i6 fed a controlled supply of water which exits from one or more openings therein to contact and cool the closure elements and closely adjacent film. As shown in Fig. 1. each secondary cooling nozzle assembly 17 extends around about IS percent to about 2S percent of the periphery of casting cylinder 11. Positioned downstream from cooling nozzle assembly 17 are water stripping means comprising one or more water suction nozzles 18 (one 6hown). and one or more air nozzles 19 (one shown) to remove cooling water from the formed integral 21076 5 closure web 20. The water stripping neans are -positioned near each closure element prior to the transfer point of integral closure web 20 from casting cylinder 11 to further cooling rolls. As 5 indicated, the dried integral closure web is then passed to and over chill rolls 21 and 21'. The web may be slit by slitters 20' mounted ju6t prior to a nip created by rolls 21' and 21". and thereafter passed to a folding device 22 such as an "A-frame" 10 folder, and then to an occlusion guide 23 and occlusion rollers 24 (one shown) thus forming integral interlocking closure film 6tock 28.

Fig. 2 illustrates in greater detail the extrusion and cooling arrangement of the present 15 invention discussed with respect to Fig. 1. In Fig. 2. film 12 may be seen exiting from slot extrusion die 10 at the film die orifice generally designated as location A. Located downstream from the exit of slot die 10 and generally equidistant from the exit 20 of slot die 10 and the tangency line (location C) of integral closure web 20 on the periphery of casting cylinder 11. are a plurality of closure element profile dies 13 (one shown) from which the formed closure elements exit at the closure die orifices. vw; 25 This location is generally designated as location B. where the extruded closure elements contact and join with film 12. The distance between location A and location B, that is, the distance between the exit of slot extrusion die 10 and the exits of closure 30 element profile dies 13 may be between about one inch and about five inches, and preferably i6 between about three inches and about three and llfo 2 7 6 5 O 25 one-half inches. Immediately upon exiting from profile dies 13. the formed molten closure elements contact film 12 and travel as integral closure web 20 toward casting roll 11. The closure element portions of integral closure web 20 are partially cooled by primary cooling nozzles 14 and 14' (only two shown) which are positioned such that coolant first contacts the closure elements at a distance less than about one inch after the exits of closure profile dies 13. The coolant can be a controlled flow of water directed onto the surface of the formed molten closure elements. The primary cooling nozzles 14 and 14" initiate cooling of the closure elements before the integral closure web 20 reaches location C which is the tangency line of integral closure web 20 on casting roll 11. The distance between location B and location C. that is. the distance from the exit of profile dies 13 and the casting roll periphery tangency line, may be between about one inch and about five inches, preferably between about one and one-half inches and about two and one-half inches. Likewise, the distance between location A and location C. that is, the distance between the exit of slot extrusion die 10 and the casting roll periphery tangency line, may be between about three inches and about eight inches. preferably between about four and three-quarter inches and about five and one-half inches. In accordance with this invention, forced cooling of the formed molten closure elements begins at a distance of les6 than about one inch after the exit6 of closure profile dies 13. • --4 2 10 In a preferred mode, primary cooling nozzleE 14 and 14' are supplied with water which has been deaerated to avoid the formation of irregular closure elements which result from non-uniform water flowing from the primary cooling nozzle exits when the entrained gas bubbles exit, such as with non-deaerated cooling water. In addition, primary cooling nozzles which initially impinge the cooling water more directly onto the closures and les6 directly onto the adjacent film have been found to result in a more stable shaping of the extruded closure elements during the cooling process. A secondary cooling nozzle assembly 17 mentioned earlier iB shown in Fig. 2 ac being a sequence of portions depicted as 17-1. 17-2. 17-3. 17-4, etc.

Fig. 3 is a greatly enlarged perspective view of the exit face of one of the closure profile dies 13 which i6 specially machined with an adhesion 61ot 13' to facilitate fusion of a formed molten 20 closure element to molten film 12 (not 6hown). The function of adhesion Blot 13* i6 to merge a closure element melt stream with the film or sheet melt stream and provide a seam-free adhesion of the two melt streams while retaining a relatively 25 di6tortion-free closure element profile shape.

Since adhesion occurs at the base portion of the closure element, and at a point after the slot film die exit, the web. hooK and base portions of the profile element suffer little or no distortion. This arrangement also allows the rate of drawdown of the respective extruded closure elements and cast film to be substantially different withom suffering distortion of the closure elements. # 210 7 6 3 Pig. 4 1b a greatly enlarged perspective view of one of the secondary cooling nozzle portions which i6 identified as 17-1 for purposes of illustration. As shown therein, portion 17-1 is 5 provided with a coolant confining region 2b to > accommodate passage therethrough of the profile portion 26 (shown schematica1ly) of one of the closure elements. It can al60 be 6een that confining region 25 is provided with one or more 10 openings 27 for passage of cooling water therethrough in the direction of the arrows, that i6, in the general direction of profile portion 26. The multiple secondary cooling nozzle portions feed a controlled stream of water to the profile portion. 15 and the nozzle portions are configured such that the profile portion travels in a region in which the water also flows. The secondary cooling nozzle assembly also has suction portions which serve to withdraw some of the spent cooling water and improve 20 closure cooling efficiency. It should be noted that the extruded closure elements are relatively thicker and contain more mass of thermoplastic material than the cast film, and thus require substantially more cooling. Further, the curved configuration of the 25 closure elements makes them more susceptible to distortion during cooling which could be aggravated by stretching in the cooling region and/or by being drawn around a cooling drum. The multiple secondary cooling nozzle portions of this invention enable 30 rapid cooling of the closure elements and reduce the time during which distortion may occur, thereby providing higher production rates. In a preferred 0> <s t ■? cr 1 U / O ' embodiment, the secondary cooling nozzle assembly is configured such that the coolant confining region therein has a shape suited to surrounding the configuration of the closure element.

Various alternatives may also be practiced pursuant to the instant invention. For example. each closure element, or various parts of the closure elements, such a6 the hook portions, the web portions, the base portion, or a flange portion, and 10 the sheet or film may each be produced from totally different thermoplastic materials thus providing unique characteristics to the integral interlocking closure film stock material and the final container products, such as a pliable closure on a 6trong. 15 6tiff container body. Likewise, different colors may be imparted to the container body and the various parts of the closure elements. In addition, the thermoplastic material employed for the closure elements may contain various additives such as slip 20 agent6 to provide unique characteristics to the final product such as a reclosable container. The film extrusion die and the closure profile dies may or may not be supplied from the same source of molten thermoplastic material. In this regard, the 25 amount of molten thermoplastic material supplied to each profile die and the film die should be accurately controlled and this may be accomplished by providing separate extruders therefor, and/or flow splitting or controlling means well known in 30 the art.

In addition, more than one pair of male and female closure elements may be simultaneously 210765 \ extruded to contact and adhere with the extruded sheet or film. Further, grasping ridges or ribs, as described in nz Patent Specification Nn. 195495, may also be simultaneously extruded either from the same die 5 bcxjy that of the closure elements, or they may be extruded separately, and they may be extruded from the same closure melt source or another source.

When present, the ridges or ribs may exit the closure profile dies at about the same distance from 10 the casting roll tangency line of the film as do the closure elements. It 6hould be noted, however, that the rib melt streams may swell slightly less than the closure profile streams and therefore preferably may exit their die body closer to the film than the 15 extruded closure elements. Still further, the slot extrusion die may be contoured to provide increased film thickness in the area(s) corresponding to the closure element(6) and/or rib(s)/ridge(s ) . Such additional film thickness may provide enhanced 20 end-use characteristics to the final container product. For example, such contouring may enhance container quality, especially for container cold temperature use reliability and also improve perceived quality by stiffening the top of the V**' 25 container. Where grasping ridges and/or contoured film thickness areas are prepared pursuant to the general concept of thi6 invention, additional preferential cooling may be provided therefor in accordance with the system(s) employed herein. 1 ^ 30 Further still, the slot extrusion die and system may be substituted for with an annular film extrusion system.

The resulting integral interlocking closure film stock material may be further processed in an apparatus for forming individual reclosable containers. Since the integral interlocking closure film 6tock material comprises an integral closure web extruded in continuous form so as to provide coextensive sidewall portions of a container, and al60 provides reclosable closure elements having complementary profile portions, the 6tock material may be transversely sever-sealed at any desired spared interval or length to form reclosable containers having various sizes. contemplated that modifications thereof may be made and that some features may be employed without others, all within the spirit and scope of the invention. However, it is not desired to be limited to the illustrative embodiments for obvious modifications will occur to a person skilled in the art.

Having described the invention, it is

Claims (31)

N t \ 2L076S 20 v)u- f) f' -■' ^

1. A method of forming integral interlocking closure film stock material comprising feeding a supply of molten thermoplastic material to a film slot extrusion die. extruding a film of said thermoplastic material from an exit face of said extrusion die onto a rotating casting roll, feeding a supply of molten thermoplastic material to interlocking closure profile dies, the exits from which are located between one and five inches downstream of the exits from said slot extrusion die, extruding said molten thermoplastic material from said profile dies so that the formed closure elements immediately contact and adhere to said film to form an integral closure web at a location between one inch to five incheB prior to the tangency line of 6aid web with the periphery of said casting roll, partially cooling said closure elements by directing a controlled flow of water onto the surface of said closure elements to stabilize the shape of said closure elements, impinging a flow of air on the film portion of said web at approximately the tangency line of 6aid web and the periphery of 6aid casting roll, and further cooling said closure elements by passing said closure elements through secondary cooling nozzle assemblies feeding a controlled stream of water directly onto said closure elements.

2. A method in accordance with claim 1 including providing stripping means to remove water from said integral closure web in a zone downstream from said secondary cooling nozzle a6Bemblies. 2 L0765 - 21 -

3. A Method in accordance with claim 2 wherein said stripping means comprise one or nore water suction nozzles and air nozzles.

4. A method in accordance with claim 3 including passing 6aid integral closure web over one or more cooling rolls. E>.

A method in accordance with claim 4 wherein said cooling rolls comprise one or more chill rolls. '>J— O

6. A method in accordance with claim 4 including folding 6aid integral closure web. C

7. A method in accordance with claim 1 including positioning said slot extrusion die and said casting roll eo that said film exiting from said slot extrusion die is tangent with the periphery of said casting roll at a distance between three inches and eight inches after the exit of said 6lot extrusion die.

8. A method in accordance with claim 1 including positioning said 6lot extrusion die and said casting roll bo that 6aid film exiting from said slot extrusion die is tangent with the periphery of said casting roll at a distance between one inch and five inches after the exits of said closure profile dies. 210766 - 22 - n O

9. A method in accordance with claim 1 including partially cooling 6aid closure elements by positioning primary cooling water nozzles such that coolant first contacts said closure elements at a distance less than one inch after the exits of said closure profile dies.

10. A method in accordance with claim 9 including positioning said primary cooling water nozzles by means of positioners to avoid damaging said formed closure elements by said flow of water.

11. A method in accordance with claim 1 including positioning an air knife opposite from and facing 6aid casting roll at about the tangency line of said film and the periphery of said casting roll to impinge air on said film.

12. A method in accordance with claim 1 wherein said air knife i6 configured with either internal or external diversions to flow air away from the areas corresponding to said formed closure elements.

13. A method in accordance with claim 1 wherein said air knife is positioned 60 that the direction of the air stream from said air knife is at an angle of between 5 degreeB and 60 degrees downward from the horizontal plane.

14. A method in accordance with claim 1 wherein said secondary cooling nozzle assemblies comprise portions having one or more openings therein for passage of cooling water to said closur elements. 210765 - 23 -

15. A Method in accordance with claim 14 wherein each of 6aid secondary cooling nozzle assemblies have at least one coolant confining region therein to accommodate passage therethrough of each of said closure elements.

16. A method in accordance with claim 1 wherein the exit of said closure profile dies is generally equidistant from 6aid slot extrusion die exit face and the tangency line of said integral closure web on the periphery of said casting roll.

17. A method in accordance with claim 1 including providing said casting roll with means for rotating Baid casting roll at a controlled rate of rotation.

IS. A method in accordance with claim 1 including deaerating said water.

19. a method in accordance with claim 1 including providing said closure profile dies with an adhesion slot to facilitate seam-free adhesion of 6aid formed closure elements to said film while retaining distortion-free closure element profile shapes.

20. A method in accordance with claim 1 wherein said film slot extrusion die i6 contoured to provide increased film thickness in the area corresponding to 6aid closure elements and/or ridges.

21. A method in accordance with claim 1 including extruding grasping ridges and adhering said ridges to said film. 210765 - 24 -

22. A »ethod in accordance with claim 21 wherein Eaid ridges exit 6aid profile die6 at about the same distance from 6aid tangency line as 6aid closure elements.

23. A method in accordance with claim 21 wherein said ridge6 exit closer to said film than said closure elements.

24. An apparatus for producing integral interlocking closure film stock material comprising a film slot cast extrusion die. a plurality of closure profile dies positioned after said film extrusion die and arranged so that molten thermoplastic material exiting from said profile dies is between one inch and five inches downstream from molten thermoplastic material exiting from said film extrusion die. a rotatable casting roll positioned downstream of 6aid film extrusion die and said profile dies to receive and cool a film of molten thermoplastic material exiting from said film extrusion die at a distance between three inches and eight inches after the exit of 6aid film extrusion die and at a distance between one inch and five inches after the exits of said closure profile die6, primary cooling noz2les for partially cooling said closure elements wherein said primary cooling nozzles are positioned such that coolant first contacts said closure elements at a distance les6 than one inch below the exits of said closure profile dies, an air knife positioned opposite from and facing 6aid casting roll at about the tangency line of a 210765 - 25 - film of said molten thermoplastic material and the periphery of said casting roll to impinge air on said film, and secondary cooling nozzle assemblies positioned downstream of said air knife for feeding a controlled stream of water onto closure elements formed from molten thermoplastic material exiting from said closure profile dies.

25. An apparatus in accordance with claim 24 including water stripping means downstream from said secondary cooling nozzle assemblies.

26. An apparatus in accordance with claim 25 wherein said water stripping means comprise one or more water suction nozzles and air nozzles.

27. An apparatus in accordance with claim 24 including one or more cooling rolls downstream of said casting roll.

23. An apparatus in accordance with claim 27 wherein 6aid cooling roll6 comprise one or more chill roll6.

29. An apparatus in accordance with claim 24 including a folding device downstream of said cooling rolls.

30. An apparatus in accordance with claim 24 including a positioner for positioning each of said primary cooling nozzles.

31. An apparatus in accordance with claim 24 wherein said secondary cooling nozzle assemblies rT* T ^;Kl50CTV»l;26 -;Z10765;comprise portions having one or more openings therein for passage of cooling water.;32. An apparatus in accordance with claim 31 wherein each of said secondary cooling nozzle assemblies have at lea6t one coolant confining region therein to accommodate passage therethrough of a closure element.;33. An apparatus in accordance with claim 24 wherein 6aid closure profile die6 include an adhesion slot.;34. An apparatus in accordance with claim 24 wherein said 6lot extrusion die has an elongated opening parallel with and spaced from the periphery of said casting roll.;3b. An apparatus in accordance with claim 24 including means for rotating said casting roll at a controlled rate of rotation.;36. An apparatus in accordance with claim 24 wherein 6aid air knife i6 configured with either internal or external diversions to flow air away from the areas corresponding to said formed closure elements .;37", An apparatus in accordance with claim 24 wherein said air knife is positioned so that the direction of the air stream from said air knife is at an angle of between "5 degrees and 60;degrees downward from the horizontal plane.;^ A;i!l50CT«&;- 27 -;Integral interlocking closure film stock material prepared by feeding a supply of molten thermoplastic material to a film 6lot extrusion die. extruding a film of said thermoplastic material from an exit face of 6aid extrusion die onto the periphery of a rotatable casting roll, feeding a supply of molten thermoplastic material to interlocking closure profile dies, extruding 6aid molten thermoplastic material from said profile dies so that the formed closure elements immediately contact and adhere to said film to form an integral closure web at a location between one inch to five inches prior to the tangency line of 6aid web with the periphery of said casting roll, partially cooling said closure elements by directing a controlled flow of water onto the surface of said closure elements to stabilize the shape of said closure elements, impinging a flow of air on the film portion of said web at approximately the tangency line of said web and the periphery of said casting roll, and further cooling said closure elements by passing said closure elements through secondary cooling nozzle assemblies feeding a controlled stream of water directly onto said closure elements.;39. Integral interlocking closure film stock material prepared in accordance with claim 38 wherein the exit of 6aid profile dies is between one inch and five inches after the exit of said slot extrusion die.;-V'~;I;- 28 -;40. Integral interlocking closure film stock material prepared in accordance with claim 39 wherein said casting roll is positioned so that said film exiting from said slot extrusion die is tangent with the periphery of said casting roll at a distance between three inches and eight inches after the exit of 6aid slot extrusion die.;41 Integral interlocking closure film 6tock material prepared in accordance with claim 38 wherein said casting roll is positioned so that film exiting from said slot extrusion die i6 tangent with the periphery of said casting roll at a distance between one inch and five inches after the exits of said closure profile dies.;42. Integral interlocking closure film 6tock material prepared in accordance with claim 3S wherein 6aid closure elements are partially cooled by positioning primary cooling water nozzles such that coolant first contacts said closure elements at a distance les6 than one inch after the exits of said closure profile dies.;43. Integral interlocking closure film 6tock material prepared in accordance with claim 38 wherein the exit of said closure profile dies is generally equidistant from said extrusion die exit face and the tangency line of 6aid integral closure web on the periphery of said casting roll.;210765;- 29 -;44. A method of forming integral interlocking closure film stock material substantially as herein described with reference to any embodiment shown in the accompanying drawings.;45. An apparatus for producing integral interlocking closure film stock material substantially as herein described with reference to any embodiment shown in the accompanying drawings.;46. Integral interlocking closure film stock material prepared substantially as herein described with reference to any embodiment shown in the accompanying drawings.;47. Integral interlocking closure film stock material preoared by the method of any one of claims 1 to 23 and 44.;48. Integral interlocking closure film stock material made by the apparatus of any one of claims 24 to 37 and 45.;uAitu i hi, ic^ day oFCctebe/ „ ^ A. J. PARK & SON;agents for the AP»t.(CAsrrs;*