Patent Application
20120321225
The present invention relates to a zipper tape and a packaging bag provided with the zipper tape.
There has been typically known a packaging bag with a zipper tape (hereinafter occasionally abbreviated as a packaging bag) provided by bonding the zipper tape to an inner surface of the bag body. When such a packaging bag is filled with powdery substances and liquids as contents, the contents may leak toward a top seal beyond the zipper tape during transportation, or external air may infiltrate into the packaging bag to alter the quality of the contents.
Accordingly, in order to prevent leakage of the contents and maintain the quality of the contents by blocking external air, a zipper tape having a structure for improving air-tightness and a packaging bag with the zipper tape have been known (see Patent Literatures 1 to 3).
Patent Literature 1 discloses that a flexible rubber packing is provided on each of facing engagement-surfaces of male and female members along the longitudinal direction of the zipper tape. When the male and female members are engaged with each other, the respective flexible rubber packing are elastically deformed by being pressed between and by the facing engagement-surfaces to be brought into close contact with the facing engagement-surfaces, so that air-tightness can be obtained.
Patent Literature 2 discloses that an elastic adhesive material is continuously provided on an inner bottom of a female protrusion of a female member along the longitudinal direction of a zipper tape. When a male protrusion of a male member is engaged with the female protrusion, the elastic adhesive material of the female protrusion is pressed by a head of the male protrusion to be brought into close contact with the head of the male protrusion by elastic force of the elastic adhesive material, so that air-tightness can be obtained.
Patent Literature 3 discloses that an easily peelable plastic layer formed of polybutene, an ethylene-vinyl acetate copolymer, an ethylene-polypropylene mixture and the like is provided on a surface of a male protrusion, and the easily peelable plastic layer provides air-tightness in engagement. The easily peelable plastic layer is configured to allow cohesive peeling or interfacial peeling in opening.
Patent Literature JP-A-6-239356
Patent Literature 2 JP-A-2006-102068
Patent Literature 3 Pamphlet of International Publication WO02/38459
Examples of contents to be fed into a packaging bag with a zipper tape include: foods to be heated by a retort process, a boiling process or the like for sterilization; and pharmaceutical products, medical products, cosmetics, chemical products and groceries to be heated for sterilization.
In such cases, for instance, in the packaging bag with the zipper tape including the elastic member as disclosed in Patent Literatures 1 and 2, the elastic member is easily deformed by heat in a heating process, so that a gap may be formed between the elastic member and an engagement portion to impair air-tightness. Moreover, since the elastic member is used, odor may be generated from the elastic member in the heating process, which may make a user uncomfortable. In Patent Literature 2, since a tackifier is contained in the elastic member, the contents may be adhered to the elastic member of the zipper tape when opening the packaging bag.
On the other hand, in such an arrangement as disclosed in Patent Literature 3 in which the easily peelable plastic layer to be bonded is provided, if the easily peelable plastic layer is bonded by a bonding strength enough to resist internal pressure in the heating process, a large force is required to peel the easily peelable plastic layer in opening the bag, which may impair openability of the bag. Moreover, since the easily peelable plastic layer that is already bonded to the male protrusion is attached to a bag body to form a packaging bag with a zipper tape, a method for feeding the contents is limited to, for instance, feeding the contents from the bottom of the bag, so that versatility may not be improved.
In consideration of the above, an object of the invention is to provide a zipper tape of which air-tightness and openability are not adversely affected even in the heating process, and a packaging bag with the zipper tape.
According to an aspect of the invention, a zipper tape includes: a pair of a male member and a female member that are engageable with and disengageable from each other, the zipper tape being provided to a bag body that contains an object to be heated, in which at least one of the male member and the female member includes a fusion layer that fuses engagement contact surfaces of the male member and the female member when heating the object.
With this arrangement, the fusion layer preferably has a melting point from 60 degrees C. to 150 degrees C.
According to another aspect of the invention, a zipper tape includes: a pair of a male member and a female member that are engageable with and disengageable from each other, in which at least one of the male member and the female member includes a fusion layer capable of fusing engagement contact surfaces of the male member and the female member, the fusion layer being formed of a resin having a melting point from 60 degrees C. to 150 degrees C. lower than a melting point of each of the male member and the female member.
With this arrangement, the fusion layer is preferably formed of at least one of an ethylene-vinyl acetate copolymer resin and metallocene-type linear low-density polyethylene.
With this arrangement, the fusion layer is preferably provided in a line so as to be in linear contact with the engagement adhesion surfaces along a longitudinal direction of the tape.
Moreover, with this arrangement, the fusion layer is preferably provided in a film so as to be in surface contact with the engagement adhesion surfaces along a longitudinal direction of the tape.
According to a still another aspect of the invention, a packaging bag includes: a bag body; and the zipper tape according to the above aspect of the invention which is attached to the bag body.
According to the invention, since the engagement contact surfaces of the male member and the female member are fused through the fusion layer in the heating process, no gap is formed in the engagement portion between the male member and the female member, so that air-tightness can be obtained. Further, since the bag is openable by peeling the fusion layer, a peeling strength of the fusion layer only needs to be set by selecting a material of the fusion layer and setting dimensions of an area of the fusion layer such that the fusion layer does not require a large force for opening the bag to deteriorate an opening feeling. Accordingly, air-tightness can be improved in the heating process without impairing the opening feeling. Moreover, by appropriately selecting the material of the fusion layer, a user can be prevented from feeling uncomfortable because of characteristic odor of an elastic member.
A packaging bag provided with a zipper tape according to an exemplary embodiment of the invention will be described with reference to the attached drawings.
In this exemplary embodiment, the packaging bag provided with the zipper tape (hereinafter, abbreviated as a “packaging bag”) is exemplified by a packaging bag for packaging foods to be heat-sterilized (to be heated) in a retort process or a boiling process. However, the packaging bag is also applicable for containing an object such as pharmaceutical products, medical products, cosmetics, chemical products and groceries to be heat-sterilized (to be heated).
A packaging bag 1 according to the exemplary embodiment is filled with foods (i.e., an object) such as a retort food to be heat-sterilized for long storage. Examples of the foods to be contained include cooked foods to be heated for long storage and uncooked foods, in either solid or liquid form. As shown in
As shown in
After foods (not shown) are contained through a bottom of the bag body 10, the bottom seal base 13 is formed on the bottom side of the bag body 10 to provide a hermetically sealed condition.
For opening the bag, a user cuts off the top seal base 14 provided near the opening portion 15, and reseals the bag with the zipper tape 20.
As described above, the zipper tape 20 includes the male member 21 provided on one side and the female member 22 provided to the other side to be engaged with the male member 21, the male and female members 21 and 22 each formed of a thermoplastic resin and having a belt-like shape.
The male member 21 includes: a male belt-like base 211 sealed to the bag body 10; a head 212 having a substantially arrow shape in cross section; and a connecting portion 213 that connects the male belt-like base 211 and the head 212. The belt-like base 211, the head 212 and the connection portion 213 integrally forms the male member 21.
Similarly to the male member 21, the female member 22 includes: a female belt-like base 221 sealed to the bag body 10; and a concave groove 222 having an arc shape in cross section that is connected to the female belt-like base 221. The concave groove 222 is engageable with and disengageable from the head 212 of the male member 21. The concave groove 222 and the head 212 provide an engagement portion 23. By engagement or disengagement between the concave groove 222 and the head 212, the packaging bag 1 is sealed or opened.
Herein, the male member 21 of the zipper tape 20 of the exemplary embodiment can be obtained by co-extrusion, where the male belt-like base 211 and the head 212 and the connecting portion 213 that are formed continuously from the male belt-like base 211 are integrally formed. Likewise, the female member 22 can also be obtained by co-extrusion, where the female belt-like base 221 and the concave groove 222 formed continuously therefrom are integrally formed. When the zipper tape 20 is formed by such co-extrusion, the zipper tape 20 can be manufactured in a simplified process at low costs, and can be stably manufactured in a continuous manner.
The male member 21 and the female member 22 of the zipper tape 20 may be formed of polyethylene and polypropylene and are preferably formed of highly heat-resistant polypropylene. Specifically, thermoplastic resins such as homo-polypropylene, block-polypropylene (hereinafter, abbreviated as “BPP”), random polypropylene (hereinafter, abbreviated as “RPP”), propylene-ethylene-butene-1 random terpolymer and polyolefin-based special flexible resins (hereinafter, abbreviated as “TPO resins,” e.g., TPO manufactured by Prime Polymer Co., Ltd.), and a mixture thereof are usable.
When RPP is used as the resin forming the zipper tape 20, a melt flow rate ((hereinafter, abbreviated as “MFR”) of RPP is preferably 0.5 g/10 min to 20 g/10 min, particularly preferably 1 g/10 min to 15 g/10 min.
When MFR of RPP is less than 0.5 g/10 min, extrusion formability of the engagement portion 23 that is continuously and integrally formed with the male belt-like base 211 and the female belt-like base 221 may be deteriorated. On the other hand, when MFR is more than 20 g/10 min, tip ends of the concave groove 222 of the female member 22 may be easily closed and the connecting portion 213 of the male member 21 may be easily bent, which makes it difficult to extrude the engagement portion 23 into a predetermined reopenable/resealable shape.
Further, a fusion layer 24 is provided on an inner surface of the concave groove 222 of the female member 22. The fusion layer 24 is melted by heat when heat-sterilizing the contained foods, whereby an outer surface (i.e., engagement contact surface) of the head 212 and an inner surface (i.e., engagement contact surface) of the concave groove 222 are fused, the engagement contact surfaces being engaged with each other and facing each other.
The fusion layer 24 is made of a resin having a melting point of 60 degrees C. to 150 degrees C. In other words, the usable resin is, for instance, such a resin as are melted at the temperature of approximately 60 degrees C. to 100 degrees C. for the boiling sterilization or at the temperature of 100 degrees C. to 150 degrees C. for the heat sterilization of retort foods to be cooked with a microwave oven. Specifically, at least one of an ethylene-vinyl acetate copolymer resin (hereinafter, abbreviated as “EVA”) and metallocene-type linear low-density polyethylene (hereinafter, abbreviated as “metallocene LL”) is usable.
When the melting point of the fusion layer 24 is lower than 60 degrees C., the melted fusion layer 24 may leak out of the engagement portion 23. On the other hand, when the melting point of the fusion layer 24 is higher than 150 degrees C., the fusion layer 24 is not melted when foods are heat-sterilized. In other words, it is not possible to fuse the engagement contact surfaces of the head 212 and the concave groove 222 by heat-melting the fusion layer 24 for the heat sterilization, so that sealability cannot be improved. For instance, foods may leak out of a gap between the head 212 and the concave groove 222 by the internal pressure increased by heat for the heat sterilization. For this reason, the fusion layer 24 is made of a material having a melting point of 60 degrees C. to 150 degrees C.
The fusion layer 24 is provided in a line so as to be in linear contact with the engagement adhesion surfaces along the longitudinal direction of the tape. Specifically, plural lines (e.g., three lines) of the fusion layers 24 are provided along the longitudinal direction of the zipper tape 20 from one of the side seal bases 12 to the other of the side seal bases 12.
By sealing the thus configured zipper tape 20 to the base film 11 of the bag body 10 and forming the base film 11 into a bag, the packaging bag 1 as shown in
While the base film 11 (packaging material) for forming the bag body 10 is preferably a layered film, for instance, in which a sealant layer is layered onto a base layer (not shown), the base film 11 may be a layered film in which a layered film layer (not shown) including layers of a gas barrier layer, a light-shielding layer and a strength-reinforcing layer is provided as a middle layer between the base layer and the sealant layer, depending on a required performance. The base film 11 is made of a resin having a higher melting point than the fusion layer 24. Specifically, the base film 11 is made of a resin capable of remaining unmelted during the heat sterilization. As this resin, not only one kind of a resin is usable, but also a mixture of various resins and a copolymerized substance are usable.
Examples of the material for the base layer are preferably a biaxially-oriented polypropylene film (hereinafter, abbreviated as an “OPP film”), a biaxially-oriented polyester film such as biaxially-oriented polyethylene terephthalate film (hereinafter, abbreviated as a “PET film”) and biaxially-oriented polyethylene naphthalate film and a biaxially-oriented polyamide film such as nylon 6, nylon 66 and MXD6 (poly-meta-xylylene adipamide). Depending on needs, various engineering plastic films are also usable. One of the above may be used alone, or a combination of two or more of the above may be layered in use.
When the middle layer is a gas barrier layer, usable examples of the material for the middle layer are a film of a saponified ethylene-vinyl acetate copolymer (hereinafter, abbreviated as “EVOH”) or polyacrylonitrile (hereinafter, abbreviated as “PAN”), aluminum foil, a deposited layer of silica, alumina or aluminum and a coating layer of PVDC.
When a deposited layer of silica, alumina or aluminum or a coating layer of PVDC is used, the deposited layer and the coating layer may be formed on the inner surface 10A of the bag body 10 of the base layer by deposition or coating. Alternatively, a deposited layer and a coating layer may be formed on another biaxially-oriented nylon film (hereinafter, abbreviated as an “ONy film”), a PET film or an OPP film by deposition or coating, and the film may be layered on the middle layer.
Among the above, aluminum foil and a deposited layer of aluminum, which are opaque, can also serve as a light-shielding layer.
The layering of the base layer and the film of the middle layer can be conducted by a known dry lamination method or extrusion lamination method (sandwich lamination method).
For the sealant layer (the innermost layer), polypropylene (hereinafter, abbreviated as “CPP”) and the like are usable.
In order to layer the sealant layer, the above resins may be formed into films and layered by a dry lamination method or extrusion lamination method. Alternatively, the above resins may be layered thereon by extrusion coating.
The packaging bag 1 according to this exemplary embodiment can be easily manufactured with use of, for instance, a bag-making machine for three-sided sealing and attaching the zipper tape.
Sealing conditions (temperature, pressure, etc.) in the manufacturing can be properly determined in accordance with types of the resins for forming the zipper tape 20 and the base film 11 for forming the bag body 10.
Opening and Resealing Operation of Packaging Bag
Firstly, the packaging bag 1 is heat-sterilized for long storage of the foods contained therein.
By this heat sterilization, the fusion layer 24 is melted to fuse the facing engagement contact surfaces of the head 212 of the male member 21 and the concave groove 222 of the female member 22, in which the head 212 and the concave groove 222 are engaged with each other.
The user cuts off the top seal base 14 to open the opening portion 15 and takes out the heat-sterilized foods.
For resealing the packaging bag 1 containing left-over foods, the head 212 and the concave groove 222 are re-engaged to seal the opening portion 15.
Here, melting of the fusion layer 24 during the heat sterilization improves engagement strength and air-tightness between the head 212 and the concave groove 222. Accordingly, even if the internal pressure within the containing space 16 is increased by the heat sterilization, the foods does not leak out, for instance, through a gap between the head 212 and the concave groove 222.
Moreover, by forming the fusion layer 24 of EVA or metallocene LL, a characteristic odor of a conventional elastic member is not generated during the heat sterilization. Accordingly, the user can be prevented from feeling uncomfortable.
By pulling the opening portion 15 apart by pinching opening edges thereof, the head 212 and the concave groove 222 which are fused through the fusion layer 24 are peeled away to release the engagement, so that the opening portion 15 is opened. The foods contained inside are taken out under this condition.
According to this exemplary embodiment, the following advantages can be obtained.
Specifically, in the above exemplary embodiment, in relation to the head 212 of the male member 21 and the concave groove 222 of the female member 22 that are engageable with and disengageable from each other, the fusion layer 24 is provided on the inner surface of the concave groove 222. When the foods are heat-sterilized for long storage, the fusion layer 24 fuses the outer surface (i.e., the engagement contact surface) of the head 212 and the inner surface (i.e., the engagement contact surface) of the concave groove 222, the outer surface and the inner surface facing each other.
Thus, since the fusion layer 24 fuses the engagement contact surfaces of the head 212 of the male member 21 and the concave groove 222 of the female member 22, no gap is formed in the engagement portion between the head 212 of the male member 21 and the concave groove 222 of the female member 22, so that air-tightness can be obtained. Further, since the bag is openable by peeling the fusion layer 24, a peeling strength of the fusion layer 24 only needs to be set by selecting a material of the fusion layer 24 or setting dimensions of an area of the fusion layer 24 such that the fusion layer 24 does not require a large force for opening the bag to deteriorate an opening feeling. Accordingly, sealability by the heating process can be improved without deteriorating the opening feeling. In other words, the peeling strength is easily adjusted by an arrangement of the fusion layer 24, so that such an arrangement with a favorable opening feeling and air-tightness can be easily obtained.
In the exemplary embodiment, the bag contains foods to be heat-sterilized for long storage and includes the fusion layer 24 having a melting point of 60 degrees C. to 150 degrees C.
With this arrangement, the fusion layer 24 can be suitably melted at the temperature of the heat sterilization (heating process) in the boiling process, the retort process or the like, whereby the engagement contact surfaces of the head 212 and the concave groove 222 can be fused to each other. Accordingly, the foods can be prevented from leaking out of the gap between the head 212 and the concave groove 222.
In the exemplary embodiment, EVA and metallocene LL are used as the fusion layer 24.
Accordingly, characteristic odor of the elastic member is not generated during the heat sterilization to prevent the user from feeling uncomfortable.
Moreover, in the exemplary embodiment, three lines of the fusion layers 24 are provided on the engagement contact surfaces of the head 212 and the concave groove 222.
In comparison with an arrangement of a single line of the fusion layer 24, this arrangement can provide a higher hermetically-sealed condition against the outside of the containing space 16. Moreover, in comparison with an arrangement in which the outer surface of the head 212 and the inner surface of the concave groove 222 are entirely fused to each other, this arrangement can provide a sufficient hermetically-sealed condition even with less amount of a material. Further, in comparison with the arrangement in which the outer surface of the head 212 and the inner surface of the concave groove 222 are entirely fused to each other, this arrangement requires only a small force for opening the opening portion 15 and can provide a lighter and favorable opening feeling.
In the exemplary embodiment, the fusion layer 24 is provided on the concave groove 222.
Accordingly, the food, even in a liquid form, is unlikely to be brought into contact with the fusion layer 24, so that inconvenience to make the user feel uncomfortable can be prevented.
The scope of the invention is not limited to the above-described embodiments but also includes modifications and improvements as long as an object of the invention can be achieved.
The arrangement with three lines of the fusion layers 24 is exemplarily described. However, only a single line of the fusion layer 24 may be provided as shown in
The fusion layer 24 may be provided not only at the top of the head 212 but also at both longitudinal sides of the head 212 as shown in
Further, as shown in
Although the fusion layer 24 is provided on the concave groove 222, the fusion layer 24 may be provided on the outer surface of the head 212 or may be provided on each of the head 212 and the concave groove 222.
When the fusion layer 24 is provided on each of the head 212 and the concave groove 222, the fusion layer 24 of the head 212 and the fusion layer 24 of the concave groove 222 are preferably provided at separate positions so as not to face each other, in order to efficiently obtain a higher sealability using less amount of the material.
For instance, as shown in
The zipper tape 42 shown in
When the fusion layer 24 is provided on the engagement portion 23A near the containing space 16 as shown in
Moreover, as shown in
With the arrangement shown in
The invention is applicable to a zipper tape attached to a bag body to be filled with foods, medicines and the like to be heated for sterilization and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-041942 | Feb 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/051754 | 1/28/2011 | WO | 00 | 8/27/2012 |
