NZ211483A - Extruding plastics fastener and accessory strip and uniting with film - Google Patents

Description

21 Priority Date(s): /$ ??r Complete Specification Filed: Ctass-. M'.Z </<?.?.

Publication Date: P.O. Journal, No: PATENTS FORM NO. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "METHOD OF FORMING PLASTIC FASTENER' AND PLASTIC ACCESSORY STRIPS AND UNITING THE SAME WITH A FILM" -U-«dU'~«Q &/=> <Se.iso.-> Ni WE KABUSHIKI KAISHA SEISAN NIPPON SHA, LTD 1 p>pO—> SioC*, LjhcJ ;>y^of New ;Kojimachi Building,3,5-chome, Kojimachi, Chiyoda-ku, Tokyo, Japan, «* hereby declare the invention, for Which-I-/we pray that a patent may be granted to ae/us, and the method by Which it is to be performed, to be particularly described in and by the following statement 'forFowffcf by patre T 2 I 1483 TITLE OF THE INVENTION METHOD OF FORMING PLASTIC FASTENER AND PLASTIC ACCESSORY STRIPS AND UNITING. THE SAME WITH A FILM BACKGROUND OF THE INVENTION Field of the Invention and Related Art Statement The present invention relates to a method of forming a plastic fastener and a plastic accessory strips and uniting the same with a film having a single or a plurality of layers.

Such bags or sacks are known as having a body made of a single or a plurality of layers and an opening which can be sealed or unsealed by means of a plastic fastener.

In such bags or sacks, the sealing/unsealing function can be obtained by providing ribs in the vicinity of the plastic fastener so as to prevent the adherence of the film at the end surface of the opening and to facilitate the pinching of the opening and by bonding fillets for reinforcing the bag or sack to the portion between the ribs and the plastic fastener.

The present invention is concerned with a method of producing the film having a plastic fastener and accessory strips such as the ribs and the fillets, as a previous step for the process for producing a bag or a sack of the kind described.

As shown in Fig. 1, this type of film is produced by extruding the accessory strips such as the ribs 2, fillets 3 and so forth, as well as the fastener having the male profile 4 and female profile 5, onto a flat film 1 and bonding them to the latter by the heat which has been imparted during forming by extrusion. - 1^- 2114 The conventional forming and uniting method, as shown in Fig. 2, employs a single die 6 which simultaneously extrudes and forms the accessory strips 7 such as the ribs 2 and the fillets 3 and the plastic fastener including the male and female profiles 4,5. The extruded accessory strips 7 and the fastener 8 are bonded to the film 1 which runs along a bonding roll 9 disposed in the vicinity of the die 6, by the possessed heat. Then, the accessory strips 7 is pressed by means of a press roll 10 onto the film 1 which is then forwarded to a cooling step 11.

This conventional method, however, encountered various problems because of the fact that the accessory strips 7 and the fastener 8 having different forms and material composition weight ratios are extruded and formed by a single die 6 under the same temperature condition.

Namely, the fastener and the accessory strips, which are different in shapes and weight, should be formed at different optimum temperatures. As long as the extrusion is made with a single die, however, it is not allowed to use different temperatures, so that the extrusion is made at a temperature which is optimum either for the fastener or the accessory strips. Assuming here that the die temperature is set at a level optimum for the extrusion of the fastener., the accessory strips may fail to be united with the film 1 if the bonding thereof is made under the same condition as the fastener 8, because the accessory strips 7 exhibits a greater heat radiation than the fastener 8 due to its specific weight smaller than that of the fastener 8 and due to its 1 1483 thin-walled flat form presenting a greater heat radiation surface area. To the contrary, if the extrusion is made at a die temperature suitable for the bonding of the accessory strips, such a die temperature is too high for the extrusion of the fastener so that the fastener is molten undesirably.

Another problem involved by the conventional method is as follows. Namely, in the conventional method, the fastener and the accessory strips are bonded to the film on the same roll 9. Thus, when the accessory strips 7 is pressed by a press roll 10, the portion of the roll adjacent to the fastener 8 is also pressed to cause an elastic deformation of the rubber constituting the roll 9, to form indentations in that portion of the rubber. Such indentation causes various problems such as bonding of the fastener at inclination, deformation of the fastener itself, and so forth.

Thus, the bonding roll 9 is continuously pressed by the press roll 10 so that the pressed portion of the roll is locally degraded and plastically deformed to lose the elasticity of the rubber and to allow the formation of indentations in the bonding surface of the roll, resulting in the bonding of the fastener 8 at an inclination or deformation of the fastener 8 itself.

OBJECT AND SUMMARY OF THE INVENTION To obviate this problem, the present invention proposes a method in which a die for extruding the accessory strips and a die for extruding the fastener are arranged on an extruder in a side-by-side fashion, so as to let the 2 114 2 forming temperature of said die for extruding said accessory strips higher than the forming temperature of said die for extruding said fastener, so that the fastener and the accessory strips are extruded separately and then welded and bonded to the film running on the bonding roll.

•BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view of a film to which a plastic fastener and accessory strips have been bonded; Fig. 2 is an illustration of a conventional method for bonding a fastener and accessory strips to the plastic film as shown in Fig. 1; Fig. 3 is an illustration of a method of the invention; and Fig. 4 is a view as viewed in the direction of an arrow IV.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS A preferred embodiment of the invention will be described hereinunder with reference to Figs. 3 and 4. Referring to these Figures, a first forming die 12 for extruding the accessory strips 7 and a second forming die 13 for extruding the fastener 8 having the male and female profiles 4,5 are arranged independently of and in a side-by-side fashion to each other and alongside of the extruder 18. And, the forming temperature of the . first forming die. 12" arranged as it become higher than the forming temperature of the . second die 13. The film 1 211483 unrolled from a bobbin and the accessory strips 7 extruded from said first forming die 12 are adapted to join in each other on a roll 14 which is disposed in the vicinity of the first forming die 12. A press roll 16 for pressing the accessory strips 7 onto the film 1 and an emboss roll 17 opposing to the press roll 16 are disposed in the vicinity of the roll 14.

On the other hand, a roll 15 disposed in the vicinity of the second die 13 is adapted to bond the fastener 8 to the film and to guide the film with the fastener 8 to the next step of process. As shown in Fig. 4, the roll 15 has a roll 15 adapted to guide both sides of the fastener 8 bonded to the film 1. A reference numeral 11 designates a cooling step.

In operation, the accessory strips 7 such as ribs 2 and fillets 3 extruded from the first die 12 is welded to the film 1 running on the roll 14. Then, the film together with the accessory strips 7 is moved through the gap between the.press roller 16 and the emboss roll 17 so that the accessory strips 7 are pressed and bonded onto the film 1.

Subsequently, the film 1 with the accessory strips 7 is transferred onto the roll 15 adjacent to the second die 13, and the fastener 8 having male and female profiles 4,5, is extruded from the second die 13 and welded to the film 1 running on the roll 15.

The method of the invention offers the following advantages because the first die for extruding the accessory strips and the second die for extruding the fastener disposed 1? 4 8 3 in a side-by-side fashion to each other, can operate at temperatures optimum for the bonding of the accessory strips and the fastener, respectively, to the film.

First of all, it is to be noted that, since the fastener and the accessory strips are extruded at optimum temperatures, it is possible to optimize the heat possessed by the fastener and the accessory strips and to obtain the exact shapes of the same, when the fastener and the accessory strips are bonded to the film. In addition, the undesirable damaging of the bonding roll 15 can be avoided because the pressing of the accessory strips to the film for bonding the former to the latter is conducted in advance to the bonding of the fastener. Consequently, it is possible to correctly and smoothly unite the fastener with the film without suffering from any inclination and deformation of the fastener. Furthermore, the invention provided an additional advantage that, since the accessory strips are bonded to the film before the bonding of the fastener, the film portion adjacent to the accessory strips are heated advantageously, so that the fastener can be bonded to the film even when the extrusion heat of the fastener is small, i.e. even when the extrusion is made with such a heat as to leave a heat amount smaller than that required for the bonding of the fastener.

Claims (2)

211483 WHAT-WWE CLAIM IS:- tSTBTITT
1. I. A method of forming a plastics fastener and plastics accessory strips and uniting the same with a film, the method comprising: preparing an apparatus having a single extruder in which a first forming die for extruding said accessory strips and a second forming die for extruding said plastic fastener having male and female profiles are mounted independently of and in a side-by-side fashion to each other, said first forming die having a higher forming temperature than said second forming die; jointing said accessory strips extruded from said first forming die to the surface of a film which is unrolled from a bobbin and running on a bonding roll disposed in the vicinity of said first die; feeding said film together with said accessory strips to an emboss roll and, at the same time, press-bonding said accessory strips onto the surface of said film by a press roll; and feeding said film after the pressbonding of said accessory strips thereto to a bonding guide roll disposed in the vicinity of said second forming die and bonding, on said bonding guide roll, said plastic fastener extruded from said second forming die having a lower forming temperature than said first forming die onto the film surface in parallel with said accessory strips by the heat which has been imparted - 7 - -8- 2 1 I 4
2. 2. A method of forming a plastic fastener and plastic accessory strips and uniting the same with a film as hereinbefore described with reference to Figures 1, 3 and 4 of the accompanying drawings.