Patent Grant
7765649
The present invention relates to a fitting type zipper so constituted that it can be resealed and reopened, the zipper being improved in airtightness, and a zipper-equipped bag provided with the zipper.
Zipper-equipped bags provided with a fitting type zipper (fitting tool) in openable and closable at a port in and from which the content is taken have been used in many fields such as beddings, clothes, foods, chemicals and miscellaneous goods (for example, Patent Documents 1 and 2).
These zipper-equipped bags are usually produced in the following manner: a zipper formed into a tape is prepared in advance and a base film as a bag raw material is sealed with the zipper to make a bag.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 6-239356
Patent Document 2: Japanese Patent Application Publication (JP-B) No. 4-22789
In the meantime, a zipper-equipped bag of this type has the following problem. Because it is necessary to enable resealing and reopening by fitting and unfitting utilizing the elastic deformation of a male-like projection and a female-like projection formed in the zipper and to secure, a manufacturing tolerance, it is difficult to fit the above both projections to each other in a perfectly close contact condition and the airtightness of the bag cannot be secured. In order to solve such a problem, various proposals have been offered. However, there has been no satisfactory proposal for remedies yet.
For example, Patent Document 1 discloses technologies improving the airtightness by forming elastic packings united with the male and female members on the fitting wall surfaces of these members facing each other.
However, in the case of Patent Document 1, the airtightness is secured only by bring each elastic packing into close contact with the male and female-like projections. When external force such as bending or twisting force act on the zipper, a clearance is formed between the elastic packing and the projections, the airtightness is decreased significantly. This poses the problem that no airtightness can be ensured though depending on a working condition.
Also, Patent Document 2 discloses an airtight fitting tool made to have airtightness by forming an adhesive layer on the lower part of the bottom side of the internal wall surface of a female-like projection (female claw) side.
However, Patent Document 2 is designed to provide airtightness by sealing a female-like projection (female claw) and a male-like projection (male claw) with an adhesive. Therefore, the adhesion must be made higher to secure airtightness. If the adhesion is made higher, this poses the problem that strong power is required to unfit the fitting tool, causing disorders such as stickiness of the adhesive, resulting in inconvenience for actual use as a package bag.
Moreover, generally, when a zipper-equipped bag is made, a base film is sealed with a zipper and then, the zipper positioned at the side seal part is heated and pressed to crush (so-called zipper crushing) by a heat block, followed by side sealing to avoid a sealing inferior caused by the bulkiness of the zipper.
The zipper-equipped bag made in this manner has the problem that the fitting part of the male and female-like projections at the crushed part of the zipper is deformed and an air leak passage is formed through this part, so that satisfactory airtightness is not obtained even if the zipper itself has airtightness.
As mentioned above, a zipper-equipped bag of this type has the problem that not only it is difficult to provide airtightness to the zipper itself but also airtightness is impaired when making the bag. Therefore, this bag is regarded as unsuitable to applications needing airtightness such as applications for storing liquid materials or applications requiring gas barrier characteristics.
The present invention was proposed to solve such problems involved in the aforementioned prior art and it is an object of the present invention to provide a zipper which can secure the airtightness of a zipper-equipped bag to thereby make it possible to apply it widely to applications to which the zipper has been conventionally regarded as unsuitable, thereby making it possible to improve its convenience and also to provide a zipper and a zipper-equipped bag.
A zipper according to the present invention includes a male member formed with a male-like projection and a female member formed with a female-like projection, wherein the male-like projection and the female-like projection are fitted to each other along the longitudinal direction in such a manner as to enable resealing and reopening, the zipper further including an elastic viscous material which is bulged into the part where the front end side of the male-like projection is facing the inner bottom side of the female-like projection, the elastic viscous material being integrated with the male-like projection and/or the female-like projection.
This ensures that the contact between the elastic viscous material and the male-like projection or the female-like projection is well maintained due to the adhesive force and elastic force of the elastic viscous material, whereby the airtightness of the zipper can be secured.
In the zipper according to the present invention, if the elastic viscous material is disposed on at least the part corresponding to the zipper crushed part present when the zipper is applied to a bag base material to make a bag, the generation of an air leak passage in the crushed part of the zipper can be prevented. Also, if the elastic viscous material is continuously formed along the longitudinal direction of the male-like projection and/or the female-like projection, the airtightness of the zipper itself can be secured.
Also, the material used for the elastic viscous material is preferably one including a synthetic rubber type polymer and an adhesion-imparting agent and the hardness of the elastic viscous material is preferably 2 to 20 N/1 cm3 and the adhesive strength of the elastic viscous material is preferably 2 to 8 N/10 mm.
Also, in order to improve the airtightness of the zipper, the shoulder part of the male-like projection is preferably brought into close contact with the part of the opening part side of the female-like projection by forced power acting on the female-like projection owing to the elastic force of the elastic viscous material when the male-like projection is fitted in the female-like projection. Also, the proportion of the elastic viscous material in a space formed between the male-like projection and the female-like projection when the male-like projection is fitted in the female-like projection is preferably 30 to 80% in terms of sectional area ratio on the surface perpendicular to the longitudinal direction of the zipper.
On the other hand, a zipper-equipped bag according to the present invention has a structure including a zipper as those mentioned above. This enables the provision of an airtight bag equipped with a zipper.
According to the present invention, the contact between the elastic viscous material and the male-like projection or the female-like projection is well maintained due to the adhesive force and elastic force of the elastic viscous material, whereby the airtightness of the zipper can be secured. This ensures that it is possible to apply the zipper widely to applications needing airtightness such as applications for storing liquid materials and applications requiring gas barrier characteristics to which the zipper has been conventionally regarded as unsuitable, thereby making it possible to improve its convenience.
Preferred embodiments according to the present invention will be explained with reference to the drawings.
A bag 1 shown in
When providing the side seal 11 to the side edge of the bag 1, the part of the zipper 2 protruding into the side seal side 11 and including the part provided with the side seal 11 is heated and pressed to crush into a crushed part 5 and then, the side seal 11 is provided. Outline of the above part of zipper 2 is shown using the dotted line in the figure.
Also, although, in the illustrated example, the upper edge of the bag 1 is an unsealed part in the figure, it is provided with a top seal after the content is filled. The top seal is provided on the side closer to the upper edge than the line connecting paired right and left notches 12.
This ensures that after the upper edge part (provided with the top seal) of the bag 1 is cut away to open the bag 1 by utilizing the notch 12, the mouth part of the bag 1 can be closed or opened by resealing or reopening of the zipper 2.
The zipper 2 in this embodiment is constituted of paired male member 2a and female member 2b as shown in
The male member 2a is provided with a base part 21a formed continuously like a tape. A male-like projection 22a constituted of a head part 221a and a connecting part 222a connecting the head part 221a with the base part 21a is provided on one surface of the base part 21a and these parts are integrated. Then, the other surface of the base part 21a is heat-sealed with the base film 10a.
Similarly, the female member 2b is provided with a base part 21b formed continuously like a tape. A female-like projection 22b constituted of a pair of hook parts 221b and 221b is provided on one surface of the base part 21b and these parts are integrated. Then, the other surface of the base part 21b is heat-sealed with the base film 10b.
As shown in
The specific shapes of the male-like projection 22a and female-like projection 22b are not limited to those shown in the figure as long as these projections have fitting shapes which are paired and fitted to each other.
The aforementioned male member 2a and female member 2b may be formed, for example, by extrusion molding of a thermoplastic resin. As the thermoplastic resin, for example, a polyolefin type resin such as polypropylene and polyethylene or an ethylene/methacrylic acid copolymer may be used.
The zipper 2 may have a multilayer structure using plural resins in consideration of the fitting characteristics of the zipper 2, the sealing strength and sealing characteristics of the zipper 2 with the base films 10a and 10b.
Also, the same thermoplastic resin may be used for the base films 10a and 10b themselves or a sealing layer disposed in contact with the zipper 2 in the case where the base films 10a and 10b are respectively a multilayer. Biaxially oriented nylon, biaxially oriented polyethylene terephthalate or biaxially oriented polypropylene may be laminated together with the heat seal layer as a surface layer in consideration of heat sealing characteristics with the zipper 2 and of a function as a bag, and an aluminum foil or an ethylene/vinyl alcohol copolymer film may be laminated as an intermediate layer in consideration of barrier characteristics.
In this embodiment, as shown in
The elastic viscous material 4 may be integrated with the female member 2b simultaneously when the female member 2b is molded by extrusion-supplying a material forming the elastic viscous material 4 to the inner bottom 222b so as to carry out co-extrusion when the female member 2b is extrusion-molded. However, the elastic viscous material 4 may be formed by post-processing on the female member 2b which has been formed in advance.
In this embodiment, the elastic viscous material 4 is pressed by the head part 221a of the male-like projection 22a and brought into contact with the head part 221a of male-like projection 22a with undergoing elastic deformation when the male-like projection 22a is fitted in the female-like projection 22b and is also brought into close contact with the surface on the front end side of the head part 221a by its adhesive force and elastic force. Also, the male-like projection 22a is pressed back by the elastic force of the elastic viscous material 4 with the result that the shoulder part 223a of the male-like projection 22a is brought into close contact with the front end part 223b of the hook part 221b of the female-like projection 22b.
Specifically, as shown by the dotted line in
In the example illustrate here, the shoulder part 223a of the male-like projection 22a is brought into close contact with the front end part 223b of the hook part 221b of the female-like projection 22b. However, it is only required that optional parts positioned on the opening part 224b side of the female-like projection 22b are brought into close contact with the shoulder part 223a of the male-like projection 22a and there is no particular limitation to the specific embodiment of the contact condition.
Specifically, the reason is that the above structure is intended to make the zipper 2 airtight without fail by the close contact at total of three points including the close contact at two points and the close contact between the male-like projection 22a and the elastic viscous material 4.
Also, the elastic viscous material 4 is not limited to that of the embodiment in which it is formed on the female-like projection 22b side, but may be formed on the optional positions of the male-like projection 22a or both the male-like projection 22a and the female-like projection 22b insofar as it produces the same action effect. It is however preferable to form the elastic viscous material 4 on the inner bottom 222b of the female-like projection 22b to prevent fingers from touching the elastic viscous material 4 in consideration of handling in the condition that the fitting is released.
Between the male-like projection 22a and female-like projection 22b which are fitted in this state, a total of three contact parts including the contact part formed by the head part 221a of the male-like projection 22a and the elastic viscous material 4 and the two close contact parts formed between the shoulder parts 223a of the male-like projection 22a and each front end part 223b of the hook parts 221b of the female-like projection 22b resultantly exist.
Therefore, even in the working situation where the contact of, for example, one or two contact parts fails, the contact at other contact parts is maintained. Also, the elastic viscous material has moderate adhesive strength and therefore, the contact between the surface of the front end side of the head part 221a of the male-like projection 22a and elastic viscous material 4 is maintained also by the adhesive strength of the elastic viscous material 4.
According to this embodiment as mentioned above, even in working situations where external force such as bending force or twisting force acts on the zipper 2 as well as a situation where the zipper is used in a normal condition, the close contact between the male-like projection 22a and the female-like projection 22b or the elastic viscous material 4 is maintained, whereby sufficient airtightness can be secured.
Here, the head part 221a of the male-like projection 22a and the elastic viscous material 4 are brought into close contact with each other by the adhesive strength of the elastic viscous material 4 and therefore, particularly, the contact at the contact part formed between the head part 221a of the male-like projection 22a and the elastic viscous material 4 is not impaired with ease.
For this, as shown in, for example,
Also, as mentioned above, a zipper-equipped bag of this type has the problem that the fitting part of the male and female-like projections at the crushed part of the zipper is deformed and an air leak passage is formed through this part, so that satisfactory airtightness is not obtained even if the zipper itself has airtightness. Such a leak passage is usually generated at the boundary 5a between the zipper 2 and the crushed part 5.
In this embodiment, on the other hand, even if the fitting part of the male-like projection 22a and female-like projection 22b at the boundary 5a between the zipper 2 and the crushed part 5 of the zipper is deformed, the elastic viscous material 4 is spread over the inside wall surface of the female-like projection 22b so as to fill the space formed between the male projection 22a and the female projection 22b as shown by its outline in
The hardness of the elastic viscous material 4 in this embodiment is preferably 2 to 20 N/1 cm3 and particularly preferably 3 to 10 N/1 cm3.
When the hardness is less than the above range, the force for pressing the male-like projection 22a back is low in the aforementioned fitting condition, resulting in that the contact between the shoulder part 223a of the male-like projection 22a and the front end part 223b of the hook part 221b of the female-like projection 22b is unsatisfactory.
When the hardness exceeds the above range, the elastic viscous material 4 is elastically deformed with difficulty, which is a hindrance to the fitting of the male-like projection 22a to the female-like projection 22b, which makes it difficult to fit the both to each other.
Here, the hardness of the elastic viscous material 4 may be measured according to JIS K7215, and means a value measured in the following manner. Specifically, the elastic viscous material 4 is cut into a cube having a volume of 10 mm3 to make a test piece. And then, using a measuring device (for example, a digital force gauge manufactured by IMADA CO., LTD may be utilized) fitted with an indenter having a tip angle (apex angle) of 40°, the indenter is pressed against the elastic viscous material 4 with increasing force to measure the value of force when the elastic viscous material 4 is crushed by 50% (5 mm) by the indenter.
Also, the adhesive strength of the elastic viscous material is preferably 2 to 8 N/10 mm and particularly preferably 3 to 6 N/10 mm.
When the adhesive strength is less than the above range, the contact with the male-like projection 22a is insufficient and the condition of the contact with the male-like projection 22a due to the adhesive force of the elastic viscous material 4 cannot be maintained when external force such as bending force or twisting force acts on the zipper 2.
When the adhesive strength exceeds the above range, not only it becomes difficult to unfit the engagement of the male-like projection 22a with the female-like projection 22b but also disorders such as sticking are caused, resulting in inconvenience for actual use.
Here, the adhesive force means the largest load when a test piece prepared by applying an adhesive material in a thickness of 20 μm to a PET film 50 μm in thickness is brought into close contact with SUS (Steel Use Stainless) and then, the test piece is peeled from SUS at an angle of 180° at a measuring temperature of 20° C. by a tensile tester. This maximum load is defined as 180° peeling adhesive strength.
Moreover, when the elastic viscous material 4 is formed, the size of the elastic viscous material 4 preferably one satisfying the condition that the proportion of the elastic viscous material 4 in a space S (see
When the size is less than the above range, the contact area between the elastically deformed elastic viscous material 4 and the male-like projection 22a is small and it is therefore difficult to maintain the contact condition of the both, with the result that sufficient airtightness is not obtained. Also, in order to maintain the close contact condition, the adhesive force of the elastic viscous material 4 must be increased as much as the contact area is decreased. However, if the adhesive strength of the elastic viscous material 4 is excessively strong, disorders like those as mentioned above are caused.
When the size exceeds the above range, this is a hindrance to the fitting of the male-like projection 22a and the female-like projection 22b, and it is therefore difficult to fit the male-like projection 22a in the female-like projection 22b.
Here, the aforementioned space S means a space formed between the male-like projection 22a and the female-like projection 22b when under the condition of normal temperature and normal pressure (25° C., 1 atom), the male-like projection 22a is fitted in the female-like projection 22b and, as shown in
In this embodiment, the hardness, adhesive strength and size of the elastic viscous material 4 are properly set within the above ranges in consideration of the elasticity of the material forming the zipper 2, the shape and dimension of the zipper 2 and the level of the airtightness to be required.
As the material of the elastic viscous material 4, an elastic one using a synthetic rubber type polymer as its major component is used and also the elastic one to which an adhesive imparting agent is further added to appropriately control the hardness and adhesive strength may be used.
As the synthetic rubber type polymer, synthetic rubber type polymers such as a styrene type block polymer, butyl rubber, partially crosslinked butyl type and polyisobutylene type are exemplified. Among these polymers, particularly, a styrene type block polymer is preferable in view of material balance.
Specific examples of the styrene type block polymer include SBS (styrene/butadiene/styrene block polymer), SIS (styrene/isoprene/styrene block polymer), SEBS (styrene/ethylene butylene/styrene block polymer), SEPS (styrene/ethylene propylene/styrene block polymer) and SIBS (styrene/isobutylene/styrene block polymer). Particularly, a styrene type block polymer containing a saturated hydrocarbon is preferable as the rubber component in view of heat resistance and weatherability and SEBS (styrene/ethylene butylene/styrene block polymer), SEPS (styrene/ethylene propylene/styrene block polymer) and SIBS (styrene/isobutylene/styrene block polymer) are more preferable from the viewpoint of availability.
Also, these synthetic rubber type polymers may be used in the following condition. Specifically, according to the need, a thermoplastic resin such as a polyolefin resin, polystyrene resin, vinyl chloride resin, acryl resin or fluororesin and a plasticizer are added to the above synthetic rubber type polymer, and further an organic polymer having a saturated hydrocarbon, polyether, polyester or acryl as its principal chain skeleton and a crosslinkable functional group at the terminal of its molecule (for example, an organic polymer containing at least one silicon-containing group which has a hydroxyl group or a hydrolyzable group connected to a silicon atom and can form a siloxane bond to thereby crosslink) is mixed or kneaded and the above organic polymer is crosslinked.
Examples of the above plasticizer include thermoplastic resins such as a polyolefin resin, polystyrene resin, vinyl chloride resin, acrylic resin and fluororesin, polyvinyl type oligomers such as a polybutene, hydrogenated polybutene, hydrogenated α-olefin oligomer and atactic polypropylene, aromatic oligomers such as biphenyl and triphenyl, hydrogenated polyene type oligomers such as a hydrogenated liquid polybutadiene, paraffin type oligomers such as paraffin oil and chlorinated paraffin, cycloparaffin type oligomers such as naphthenic oil, phthalates such as dibutyl phthalate, diheptyl phthalate, di(2-ethylhexyl)phthalate, butylbenzyl phthalate, di-n-octyl phthalate, diisononyl phthalate, diisodecyl phthalate and diundecylphthalate, non-aromatic dibasic acid esters such as di(2-ethylhexyl) adipate, di-n-octyl adipate, diisononyl adipate, diisodecyl adipate, di(2-ethylhexyl)sebacate and 2-ethylhexyl tetrahydrophthalate, aromatic esters such as tri-2-ethylhexyl trimellitate and triisodecyl trimellitate, fatty acid esters such as butyl oleate, methyl acetylricinolate and pentaerythritol ester, esters of polyalkylene glycols such as diethylene glycol benzoate and triethylene glycol dibenzoate, phosphates such as tricresyl phosphate and tributyl phosphate and epoxy plasticizers such as epoxidated soybean oil and epoxidated linseed oil.
Examples of the adhesion imparting agent include aromatic hydrocarbon type resins, aliphatic hydrocarbon type resins, hydrogenated alicyclic hydrocarbon type resins, alicyclic hydrocarbon type resins, Coumarone resins, terpene type resins and rosin derivatives.
Then, the present invention will be explained in more detail by way of specific examples.
A low-density polyethylene was melt-extruded to extrusion-mold a female member and at the same time, an elastic viscous material containing a SIS-type synthetic rubber as its major component (Morescomelt LT-170, manufactured by Matsumura Oil Research corp.) was extruded to the inner bottom of the female member to integrate it with the female member as shown in
The shapes of the male member and female member were designed to be almost the same as those shown in
A male member and a female member were produced in the same manner as in Example 1 except that the shapes of these members were made almost the same as those shown in
A male member and a female member were produced in the same manner as in Example 1 except that a soft rubber containing a silicon rubber as its major component was used in place of the elastic viscous material containing a SIS type synthetic rubber as its major component.
Here, the adhesive strength of Morescomelt LT-170 used in Examples 1 and 2 was 2.7 N/10 mm in terms of 180° peeling adhesive strength. Also, the hardness of Morescomelt LT-170 was 3.2 N/1 cm3. On the other hand, the soft rubber used in Comparative Example 1 had no adhesive strength and a hardness of 30 N/1 cm3.
(Evaluation)
Each zipper produced in Examples 1 and 2 and Comparative Example 1 was applied to a base film, on which a biaxially oriented nylon film (15 μm) and straight-chain low-density polyethylene (50 μm) were dry-laminated, by heat sealing. After the zipper was crushed, a bottom material was applied to the side opposite to the zipper side by heat sealing and the side part perpendicular to the zipper was heat-sealed to make a standing bag of 150 mm×150 mm, thereby manufacturing a zipper-equipped bag.
One of the obtained zipper-equipped bags in these examples was filled with 100 ml of water and the other was filled with 100 ml of air. The bag filled with 100 ml of water was turned upside down and the bag filled with air was soaked in water to measure leakage. The results of the evaluation are as follows.
Although the invention has been described in its preferred embodiment, it is needless to say that the present invention is not limited only to the above embodiments and various modifications are possible within the scope of the invention.
For example, the elastic viscous material 4 is provided continuously along the longitudinal direction on the inner bottom 22b of the female-like projection 22b in the aforementioned embodiment. However, if the elastic viscous material 4 is provided on the part corresponding to the zipper crushed part 5 when at least the zipper 2 is applied to the base films 10a and 10b by heat sealing to make a bag, an air leak passage produced usually at the boundary 5a between the zipper 2 and the crushed part 5 can be prevented. In this case, other proper measures may be applied to the zipper 2 itself to impart airtightness.
Also, the standing bag is exemplified to offer the explanations in the foregoing embodiment. However, the zipper-equipped bag may have an optional shape such as a flat bag.
As explained above, the present invention may be widely utilized for a zipper-equipped bag which is provided with a fitting type zipper at the mouth part from which the content is taken out or in such that it is freely opened or closed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-291869 | Oct 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2005/018269 | 10/3/2005 | WO | 00 | 4/3/2007 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2006/038578 | 4/13/2006 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3440696 | Staller | Apr 1969 | A |
| 5293672 | Tominaga et al. | Mar 1994 | A |
| 7514143 | Matsumura et al. | Apr 2009 | B2 |
| 20040091179 | Anderson | May 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 06239356 | Aug 1994 | JP |
| 2000344251 | Dec 2000 | JP |
| 2003319806 | Nov 2003 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20070266532 A1 | Nov 2007 | US |
