Zipper and zipper-equipped bag

A tearing guide strip 23 is integrated with a base part 21a or 21b of at least one of a male member 2a and a female member 2b constituting a zipper 2 in a peelable manner to improve the tearing unsealing ability of a zipper-equipped bag provided with an interlocking type zipper enabling resealing and unsealing after the bag is unsealed.

TECHNICAL FIELD

The present invention relates to a zipper which can be improved in unsealing ability and a zipper-equipped bag provided with such a zipper, in a zipper-equipped bag provided with an interlocking-type zipper so as to enable the bag to be resealed and unsealed after the bag is unsealed.

BACKGROUND ART

Zipper-equipped bag which are provided with an interlocking-type zipper (interlocking fitting tool) at their mouth parts where the content is taken in and out and can be resealed and unsealed after the bag is unsealed have been used in many fields such as foods, chemicals and miscellaneous goods (for example, Patent Documents 1, 2 and 3).

These zipper-equipped bags are usually produced in the following manner: a zipper formed into a tape form is prepared in advance and a base film as a bag raw material is sealed with the zipper to make a bag.

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

In the meantime, this type of zipper-equipped bag is generally so constituted that it can be unsealed by tearing a bag raw material at the unsealing part by the hand without using scissors or the like. However, if the bag raw material is not well torn, it causes inconvenience in use after the bag is unsealed.

For example, if the bag raw material is cut so excessively when the bag is unsealed that the part to be held by the hand when the bag is unsealed by releasing the interlocking of the zipper or the sizes of this part are uneven, the bag is put in the state where it is unsealed with difficulty. Also, if even the zipper is cut by mistake when the bag raw material is torn, resealing with the zipper cannot be attained.

For this, various proposals have been offered to be able to tear the fixed position of the bag raw material.

For example, in Patent Document 1, a bag is reported in which an easily cuttable resin layer having a specific composition is disposed at the tape part of a zipper (bandy fitting tool) and the bag is unsealed along this easily cuttable resin layer.

However, in the bag proposed in Patent Document 1, the easily cuttable resin layer is formed of a composition including a mixture of two types of resin such that the direction in which the bag is unsealed is fixed by breaking the easily cuttable resin layer when the bag is unsealed. There is therefore the problem that fibrous cutting scum is generated on the broken surface, with the result that the content is contaminated with such cutting scum.

Also, in the case of the zipper of Patent Document 1, it is necessary to prevent the easily cuttable resin layer from being heated by the heat from a heat seat bar when the zipper is bound with a base film used as a bag raw material by sealing such that the easily cuttable resin layer is prevented from adhering to the base film (for example, Patent Document 1, Paragraph No. [0018]). This zipper has the problem that, for example, not only it is necessary to prepare a heat seal bar having a predetermined seal surface but also strict alignment is required when the zipper is bound with the base film by sealing, requiring troublesome time and labor for the binding of the zipper with the base film. This zipper has therefore a large problem which must be improved to produce a zipper-equipped bag in an efficient manner.

Also, in Patent Document 2, a zipper-equipped bag (fastener bag) is proposed which is so devised that a cut tape is fixed to between a male zipper member and a female zipper member provided inside of a baggy container produced by binding the side edges of one lapping material with each other by heat sealing and a part of the baggy container is cut by the cut tape to unseal the container.

Although general automatic packaging machines may be applied to the fastener bag of Patent Document 2, so that this fastener bag makes it possible to avoid the complication of apparatuses and troublesome workings. The packaging means includes, heat-sealing the side edge of the lapping material fitted with the zipper to make a cylinder body, heat-sealing the opening part of one of both ends in the longitudinal direction of the zipper and then filling the content from the opening part of the other end (see Patent Document 2, Paragraph No. [0023]).

For this reason, the shape of the fastener bag described in Patent Document 2 is limited to a flat form and it is difficult to apply this fastener bag to a standing bag which can be formed to be self-stood and has come to be frequently used in recent years. Also, because the zipper and the cut tape are constituted as separate bodies, the zipper and the cut tape must be installed separately (see Paragraph No. [0020]). This is the reason why a further improvement in production efficiency is desired.

Also, Patent Document 3 proposes a zipper-equipped bag (packaging bag) which is so constituted that an unsealing string is fitted to the band base part of the zipper (interlocking tool) in an embedded state along the longitudinal direction and the bag can be unsealed with a fixed orientation by pulling the unsealing string.

The zipper of Patent Document 3 is free from a problem such as those mentioned above which are involved in Patent Document 1 and also, it is unnecessary to fit the zipper and the unsealing string separately to the base film by sealing. This zipper-equipped bag is very superior also in production efficiency.

However, when the bag is unsealed by pulling the unsealing string, it is necessary to tear the band base part together with the base film and therefore, power is required to unseal and it is therefore pointed out that the bag is unsealed with difficulty by a powerless person.

In the conventional art technologies as mentioned above, each bag can be unsealed by tearing a fixed position of a bag raw material using a cut tape or an unsealing string and therefore, it is not inconvenient in use after unsealed. However, there is a room for improvement to comply with an increased demand for better performance in the market.

The present invention has been proposed to solve the problems involved in the foregoing conventional art technologies. It is an object of the present invention to provide a zipper which can be improved in the tearing-unsealing ability of a zipper-equipped bag and also to provide a zipper-equipped bag.

Means for Solving the Problem

A zipper according to the present invention includes paired male member having a male projection and female member having a female projection which are interlocked with each other, the zipper being fitted to a bag and enabling the bag to be resealed and unsealed after the bag is unsealed, wherein a tearing guide strip is integrated with at least one of the base parts of the male member and female member and the tearing guide strip can be separated from the base part of the male member or female member.

A bag equipped with the zipper having such a structure according to the present invention can be easily unsealed by pulling the tearing strip to tear a bag raw material and also, the force required for unsealing can be reduced to the utmost by adjusting the binding condition of the tearing guide strip to the base part of male member or female member properly. It is therefore possible to improve the unsealing ability with ease.

Also, the zipper according to the present invention may have a structure in which in the state where it is fitted to the bag, a tearing guide strip is integrated with the end part in the width direction of the base part of the male member and/or base part of the female member positioned on the unsealing side of the bag, and the above tearing guide strip can be peeled from the above end part at the binding interface between the both.

Such a structure reduces a resistant feel when the bag raw material on the unsealing side against the zipper is torn to unseal the bag and also, it is possible to guide the direction of tearing with a fixed orientation such that the bag raw material is torn linearly along the longitudinal direction of the zipper since the tearing guide strip is integrated with the zipper such that it can be peeled from the zipper by interfacial peeling at the binding interface. For this, the bag is easily unsealed, the unsealing mouth to be formed after the bag is unsealed is formed in a well shape-reproducible manner and the bag obtained after unsealed is not resultantly inconvenient in use. Moreover, since the tearing guide strip is separated as a result of the interfacial peeling at the binding interface at which the tearing guide strip is bound with the zipper, no cutting scum is generated at the peeled surface.

Also, the zipper according to the present invention may have a structure in which the base part of the male member and/or the base part of the female member provided with the tearing guide strip is provided with a thickened part along the longitudinal direction in the part thereof in the vicinity of the tearing guide strip.

Even if the direction in which the bag raw material is torn is directed to the zipper side, such phenomenon is prevented that the zipper is torn to the vicinity of the interlocking part so that the part to be held by the hand when the interlocking of the zipper is released to reseal the bag is lost. Also, the direction in which the bag raw material is torn can be corrected to the normal direction.

The zipper according to the present invention may have a structure in which in the state where the male member is interlocked with the female member, the base part of one of the male member and the female member is extended projecting toward the unsealing side of the bag such that the length of its width is larger than that of the base part of the other of the male member and the female member, the tearing guide strip is integrated with the surface side on which the male projection or female projection is formed in the extended part of the base part of one of the male member and female member and the tearing guide strip is peelable from the base part of one of the male member and the female member.

Because in such a structure, the tearing guide strip is integrated with one of the male member and female member in such a manner as to be separable by peeling from the zipper, this reduces a resistant feel when the bag raw material on the unsealing side against the zipper is torn to unseal the bag. Also, because the part where the tearing guide strip is provided is projected more closely to the unsealing side than that of the other of the male member or female member, the direction of tearing can be guided with a fixed orientation such that the bag raw material is torn linearly along the longitudinal direction of the zipper without being disturbed by the other of the male member or female member.

For this reason, the bag is easily unsealed and the unsealing mouth formed after unsealed is formed in a well shape-reproducible manner and the bag obtained after unsealed is not resultantly inconvenient in use.

Also, the zipper according to the present invention may have a structure in which the tearing guide strip may be provided with a heat seal layer made of a resin that can be bound with the raw material forming the bag by heat sealing on the surface facing the raw material forming the bag by binding strength higher than the peeling strength between the tearing guide strip and the base part of one of the base part of the male member and the female member on which the tearing guide strip is to be formed when the zipper is fitted to the bag.

This makes it possible to effectively avoid the phenomenon that peeling is caused between the tearing guide strip and the bag raw material in unsealing and to allow the peeling of the tearing guide strip from the zipper to prevail.

Also, according to the present invention, the zipper is configured such that the peeling strength between the zipper and the tearing guide strip is preferably 15 N/15 mm or less.

This reduces the force required to peel the tearing guide strip from the zipper and therefore, a good unsealing feel is obtained because the force tearing the bag raw material is substantially the force required to unseal the bag.

Also, the tearing guide strip preferably has a higher rigidity than the base part of the male member and/or base part of the female member on which the tearing guide strip is to be provided. More specifically, the tensile elastic modulus of the tearing guide strip is preferably 1.3 to 4 times that of the base part.

This makes it possible to prevent the tearing guide strip from being broken by material destruction, bringing about good peeling and making it possible to avoid any trouble to the tearing of the bag raw material.

Also, a zipper-equipped bag according to the present invention includes a zipper fitted thereto and provided with paired male member having a male projection and female member having a female projection which are interlocked with each other and enabling the bag to be resealed and unsealed after the bag is unsealed, wherein a tearing guide strip is integrated with the base part of the male member and/or the base part of the female member which are provided in the zipper at the end part in the width direction positioned on the unsealing side of the bag in such a manner that it can be separated from the base part at the binding interface between the end part and the tearing guide strip.

Such a structure reduces a resistant feel when the bag is unsealed and also, the tearing guide strip linearly guides the direction of tearing with a fixed orientation such that the bag raw material is torn linearly along the longitudinal direction of the zipper. Therefore, the bag is easily unsealed and the unsealing mouth formed after unsealed is formed in a well shape-reproducible manner and the bag obtained after unsealed is not resultantly inconvenient in use.

Also, another zipper-equipped bag according to the present invention includes a zipper fitted thereto and provided with paired male member having a male projection and female member having a female projection which are interlocked with each other and enabling the bag to be resealed and unsealed after the bag is unsealed, wherein the base part of one of the male member or the female member is extended such that the length in the width direction is longer toward the unsealing side than that of the other of the base parts of the male member and female member, the tearing guide strip is integrated with the surface on which the male projection or the female projection is formed in the extended part of the base part of one of the male member and the female member in a freely peelable manner and also, the tearing guide strip is bound with the same surface on which the other of the male member or the female member is bound with the raw material forming the bag.

Such a structure reduces a resistant feel when the bag is unsealed and also, the tearing guide strip linearly guides the direction of tearing with a fixed orientation such that the bag raw material is torn linearly along the longitudinal direction of the zipper. Therefore, the bag is easily unsealed and the unsealing mouth formed after unsealed is formed in a well shape-reproducible manner and the bag obtained after unsealed is not resultantly inconvenient in use.

Also, another zipper-equipped bag according to the present invention may have a structure in which the surface on the side on which the male projection or the female projection is formed along the end edge of the extended part of the base part of one of the male member and the female member is bound with the same surface with which the male member or the female member of the raw material forming the bag is bound to fit the zipper.

This eliminates the necessity of releasing the interlocking of the zipper when the content is filled, thereby making it possible to avoid the adhesion of the content to the interlocking part of the zipper.

Effect of the Invention

The present invention ensures that the tearing guide strip is integrated with at least one of the male member and the female member such that it is separated by peeling, whereby the bag equipped with the zipper can be easily unsealed by only pulling the tearing guide strip to tear the bag raw material. Also, the force required for unsealing can be reduced to the utmost by adjusting the binding condition of the tearing guide strip to the base part of the male member or female member properly. It is therefore possible to improve the unsealing ability with ease.

DESCRIPTION OF THE REFERENCE NUMERALS

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments according to the present invention will be explained with reference to the drawings.

First, a zipper-equipped bag of a first embodiment according to the present invention will be explained.

FIG. 1is a front view showing the outline of the first embodiment of the zipper-equipped bag according to the present invention.

A bag1shown inFIG. 1is produced by making a bag using base films10aand10bused as a bag base material heat-sealed with a zipper2and is a so-called standing bag which is produced by providing a side seal11along the side edge in the state the bottom part3provided with a bottom seal31is folded along a fold line32.

Also, in the example illustrated, the upper edge of the bag1is unseated part. After the content is filled, a top seal13is provided.

FIG. 2is a sectional view showing a part corresponding to the section A-A ofFIG. 1in the state after the top seal13is provided. The top seal13is provided so as to form a predetermined space between the top seal13itself and the zipper2fitted to the upper part of the bag1.

The zipper2in this embodiment is constituted of paired male member2aand female member2bas shown inFIG. 2.

The male member2ais provided with a base part21aformed continuously like a tape. A male projection22aconstituted of a head part221aand a connecting part222aconnecting the head part221awith the base part21ais provided on one surface of the base part21aand these parts are formed to be integrated continuously. Then, the other surface of the base part21ais bound with the base film10aby heat sealing. Similarly, the female member2bis provided with a base part21bformed continuously like a tape. A female projection22bconstituted of a pair of hook parts221band221bis provided on one surface of the base part21band these parts are formed to be integrated continuously, Then, the other surface of the base part21bis bound with the base film10bby heat sealing.

In the zipper2constituted in this manner, the head part221aof the male projection22ais fitted in a space formed between the hook parts221band221bof the female projection22b, whereby the male projection22aand the female projection22bare interlocked with each other. Thereby the takeout port of the bag1can be sealed (resealing) after the bag is unsealed by the zipper2. When the interlocking of the zipper2(interlocking between the male projection22aand the female projection22b) is released, the takeout port of the bag1can be unsealed.

The specific shapes of the male projection22aand female projection22bare not limited to those shown in the figure as long as these projections have fitting shapes which are paired and interlocked with each other.

The male member2aand the female member2bmay be formed, for example, by extrusion molding of a thermoplastic resin and the like. As the thermoplastic resin such as, for example, a polyolefin type resin such as polypropylene, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), and an ethylene/methacrylic acid copolymer may be used. The male member2aand the female member2bmay have a multilayer structure using plural resins in consideration of the interlocking ability between the male member2aand the female member2b, the sealing strength and heat sealing characteristics of the male member2aand the female member2bwith the base films10aand10b.

Also, the same thermoplastic resin made into a film form may be used for the base films10aand10bin consideration of the sealing strength and heat sealing characteristics with the zipper2(male member2aand female member2b). The base films10aand10bmay have a multilayer structure to allow these films to exhibit various functions as the bag. In this case, for example, the inside layer to be the inside surface of the bag1is formed of the same thermoplastic resin as above as the heat seal layer for the zipper2. Also, biaxially oriented nylon, biaxially oriented polyethylene terephthalate or biaxially oriented polypropylene may be laminated together with the heat seal layer as the outside surface of the bag1, and a barrier layer made of an aluminum foil or an ethylene/vinyl alcohol copolymer film may be laminated as an intermediate layer.

In this embodiment, as shown inFIG. 2, the zipper2is provided with a tearing guide strip23integrated therewith along the longitudinal direction at the end part positioned on the side provided with the top seal13of the bag1in the state where the male member2ais bound with the base film10aby heat sealing among both ends in the width direction of the base part21aof the male member2a. In the example illustrated, the tearing guide strip23is disposed in such a manner as to be integrated with the male member2a, directly, by binding the base material231with the base part21aof the male member2aso as to be peelable at the binding interface between the both.

At this time, the peeling strength between the tearing guide strip23and the male member2ais designed to be preferably 15 N/15 mm or less. When the peeling strength exceeds this value, there is a fear that cohesive peeling is caused to generate cutting scum. Also, the force required to separate the tearing guide strip23from the male member2aby peeling is increased and it is therefore difficult to obtain a good unsealing feel. Moreover, such a disorder arises that when the bag1is unsealed, the tearing guide strip23is not separated from the male member2abut the direction of tearing is toward to the male member2a, causing a fear that the base part21aof the male member2ais eventually torn.

Here, the peeling strength between the tearing guide strip23and the male member2ameans the largest load found when the both put in a bound state are cut into a test piece having a width of 15 mm and the test piece is subjected to a tensile tester carried out at a measuring atmospheric temperature of 23° C. at a tensile rate of 200 mm/min to peel the both from each other along the direction perpendicular to the direction of the width of the test piece.

A heat seal layer232made of a resin which can be bound with the base film10aby heat sealing is disposed on the surface of the base material231facing the base film10aof the base material231and the tearing guide strip23is designed to bind with the part where the base film10ais torn when the bag1is unsealed as will be explained later.

At this time, the binding strength between the base film10aand the tearing guide strip23is preferably made to be larger than the peeling strength between the tearing guide strip23and the male member2a. It is thereby possible to efficiently avoid the peeling of the tearing guide strip23from the base film10ain unsealing and to allow the peeling of the tearing guide strip23from the male member2ato prevail.

The zipper2in this embodiment which is provided with the tearing guide strip23like this may be fitted to the bag1by heat sealing in the same manner as in the case of conventionally known zippers without using a specific heat seal bar.

In the example illustrated, the heat seal layer232is disposed such that a gap233is formed at a position apart from the end part of the base part21aof the male member2aso as not to hinder the peeling of the tearing guide strip23from the male member2a. Also, if the base material231is bound with the male member2ain a freely peelable manner and can be bound with the base film10aby a higher binding strength than the peeling strength required separating the male member2a, by heat sealing, the heat seal layer232may be eliminated as desired.

In this embodiment, the tearing guide strip23may be integrated with the male member2asimultaneously when the male member2ais molded, for example, by extrusion-supplying the material forming the tearing guide strip23to one of the end parts in the width direction so as to carry out co-extrusion.

As the resin forming the base material231, a resin incompatible with the resin used for the male member2amay be selected. For example, in the case of using polyethylene for the male member2a, polypropylene may be used for the base material231. On the other hand, polypropylene is used for the male member2a, a polyester resin such as polyethylene terephthalate and polybutylene terephthalate may be used. A modifier may be added properly to these resins, to thereby adjust the peeling strength between the both such that the both are peeled at the interface between them.

Also, as the resin forming the heat seal layer232, one which has sufficient binding strength with the base film10aand the base material231and is resistant to peeling from these materials when the bag1is unsealed is properly selected. For example, when polyethylene is used for the base film10a(or the heat seal layer for the male member2aof the base film10a) and polypropylene is used for the base material231, metallocene type linear low-density polyethylene may be used. Also, when polyethylene is used for the base film10a(or the heat seal layer for the male member2aof the base film10a) and polybutylene terephthalate is used for the base material231, a modified polyolefin type resin such as maleic acid anhydride modified polypropylene may be used.

Also, the tearing guide strip23preferably has a higher rigidity than the base part21aof the male member2ato allow itself to be well separated from the male member2awithout being disturbed by material destruction when it is separated from the male member2aand not to give hindrance to tearing of the base film10a. More specifically, the tensile elastic modulus of the tearing guide strip23is preferably 1.3 to 4 times that of the base part21aof the male member2a. At this time, the tensile elastic modulus of the tearing guide strip23is particularly preferably in a range from 300 to 2500 MPa.

When the tensile elastic modulus of the tearing guide strip23exceeds the above range, the tearing guide strip23is broken when the bag1is unsealed, leading to such a disorder that the bag1is unsealed with difficulty.

On the other hand, when the tensile elastic modulus of the tearing guide strip23is less than the above range, the tearing guide strip23has only insufficient rigidity, causing a hindrance to the peeling from the male member2aor the tearing of the base film10a.

Moreover, such a disorder is caused that the tearing guide strip23is broken and the bag1cannot be unsealed resultantly.

Also, according to such as the material, or the degree of orientation of the base film10a, the base film10ais not torn along the part where it is bound with the tearing guide strip23but the direction of tearing is toward to the part where it is bound with the male member2a, and in this case, there is the case where the male member2ais torn together with the base film10a.

In order to avoid such an event, a convex streak24is disposed along the longitudinal direction of the male member2aat a part close to the tearing guide strip23on the base part21aof the male member2aand the part is thickened than other part in the example illustrated. Thereby, even if the direction of tearing the base film10ais toward to the part where it is bound with the male member2aand a part of the male member2ais torn, it is so devised that this convex streak24prevents the male member2afrom being further torn and also corrects the tearing direction of the base film10ato the normal direction, that is, the direction along the part bound with the tearing guide strip23.

Though in the example illustrated, one convex streak24is disposed, plural convex streaks24may be disposed. There is no particular limitation to the specific shape of the thickened part insofar as it prevents the occurrence of the phenomenon that the zipper2(male member2a) is torn, so that the zipper2cannot be interlocked by the presence of the thickened part at the part close to the tearing guide strip23when the tearing direction of the base film10ais shifted, and the thickened part can correct the tearing direction of the base film10ato the normal direction.

The bag1provided with such the zipper2is unsealed by pulling the tearing guide strip23to thereby tear the part of the base film10awhich is bound with the tearing guide strip23. At the part that has been torn, an unsealing mouth14which is to be a port in and from which the content is taken is formed, as shown inFIG. 3. And, it is possible to take in or out the content by releasing the interlocking of the zipper2. Also, when the zipper2is interlocked, the bag1can be resealed. After the bag1is unsealed, the takeout port can be sealed or unsealed by the zipper2.

The tearing guide strip23(base material231) is integrated with the male member2aalong the end part of the base part21aof the male member2asuch that it is separated from the male member2aby interfacial peeling at the binding interface when the bag1is unsealed. Therefore, the resistant feel when the bag1is unsealed is reduced and also, the tearing guide strip23linearly guides the direction of tearing with a fixed orientation such that the base film10ais torn linearly along the longitudinal direction of the zipper2.

Therefore, the bag1is easily unsealed and the unsealing mouth14to be formed after the bag1is unsealed is formed in a well shape-reproducible manner and the bag1obtained after unsealed is not resultantly inconvenient in use. Moreover, the tearing guide strip23is separated from the male member2aby interfacial peeling at the binding interface and therefore, no scum is generated on the peeled surface unlike the case shown in the aforementioned Patent Document 1.

Here, an example of a specific means of tearing the base film10aby the tearing guide strip23to unseal the bag1is shown inFIG. 4.

In the example illustrated, half-cut treatment has been carried out in such a manner as to form a lug12penetrating through a part where the side seal11on which the tearing guide strip23is positioned is formed. It is so devised that at this time, the base film10bconstituting a part of the lug12is cut off from the other part of the base film10band the base film10aconstituting a part of the lug12is cut off from a part other than the part torn when the base film10ais unsealed, to form the lug12in the state where the tearing guide strip23is sandwiched between the separated base films10aand10b.

When the lug12is constituted in this manner, the lug12is, as is illustrated, picked up to pull the tearing guide strip23, whereby the base film10ais torn by the tearing guide strip23to form the unsealing mouth14.

FIG. 4(a) is an explanatory view showing the condition that the base film10ais torn by the tearing guide strip23andFIG. 4(b) is an enlarged view of a major part of the tearing guide strip23when it is pulled. Also, in the example illustrated, a part of the base part21aof the male member2aand base part21bof the female member2bis cut off and put into the state sandwiched between the base films10aand10bunder the lug12. The cut parts of the base parts21aand21bhave no influence on the resealing function of the lug12.

According to this embodiment, as mentioned above, the tearing guide strip23is integrated with the zipper2such that it is separated from the zipper2by interfacial peeling at the binding interface. Therefore, a resistant feel is reduced when the bag raw material on the unsealing side against the zipper2is torn to unseal the bag1, and also, the tearing guide strip23works so as to guide the direction of tearing with fixed orientation such that the bag raw material is linearly torn along the longitudinal direction of the zipper2. Therefore, the bag1is easily unsealed and the unsealing mouth14formed after the bag1is unsealed is formed in a well shape-reproducible manner and the bag1obtained after unsealed is not resultantly inconvenient in use.

Moreover, the tearing guide strip23is separated by interfacial peeling at the binding interface and therefore, no scum is generated on the peeled surface.

Also, in this embodiment, the following modifications of the embodiment are possible without impairing such effects.

For example, the tearing guide strip23may be provided with a guide member25on the end part opposite to the side bound with the base part21aof the male member2aalong the longitudinal direction of the end part as shown inFIG. 5.

At this time, the tearing guide strip23is integrated with the guide member25in the same binding condition as in the case binding to the base part21aof the male member2a, specifically, in the condition that the peeling strength is preferably 15 N/15 mm or less so as to enable interfacial peeling at the binding interface. Also, in the case where the tearing guide strip23is provided with the heat seal layer232, it is so devised that the same gap233is formed between the heat seal layer232and the guide member25. Also, the guide member25may be formed and integrated with the male member2asimultaneously when the male member2ais molded in such a manner as to carry out co-extrusion together with the tearing guide strip23by using the same resin material that is used for the male member2a.

The resin material used for the guide member25may be different from that for the male member2a. No particular limitation is imposed on the type of resin material used for the guide member25insofar as the guide member25can be bound with the tearing guide strip23in such a manner as not to hinder the tearing guide strip23from tearing the base film10ain almost parallel to the zipper2.

The provision of the guide member25as mentioned above makes it possible to efficiently avoid the phenomenon that when the tearing guide strip23is pulled to tear the base film10a, the base film10ais torn in a direction toward the top seal13side. Particularly, in the case where, as shown inFIG. 5, the tearing guide strip23is provided with the heat seal layer232and the gap233is formed on the both ends in the width direction of the heat seal layer232, the tearing direction of the base film10acan be guided more easily to the direction along the part where the base film10ais bound with the tearing guide strip23such that the base film10ais torn along the gap233.

Here, in the example shown inFIG. 5, it is so devised that when the guide member25is disposed together with the tearing guide strip23on the base part21aof the male member2a, the length of the base part21bof the male member2bin the width direction is extended to the top seal13side such that the edge part of the base part21bon the top seal13side is overlapped on the tearing guide strip23and the guide member25. This is to avoid the occurrence of the phenomenon that the tearing guide strip23(or the base material231of the tearing guide strip23) is eventually brought into contact with the base film10bdisposed on the opposite side. In this case, it is only required for the extended part to be formed such that it is overlapped on at least the tearing guide strip23.

Such a structure makes it possible more exactly to tear the base film10aof the bag1with ease by the tearing guide strip23. This reason is as follows.

Specifically, generally the zipper2(male member2aand female member2b) and the bag1(base films10aand10b) are formed using the chemically same materials to bind the male member2aand female member2bof the zipper2firmly with the base films10aand10bof the bag1respectively by heat sealing. For example, linear low-density polyethylene (or linear low-density polyethylene polymerized using a metallocene catalyst) may be selected as the base films10aand10b(or heat seal layers (not shown) laminated on the base films10aand10b), low-density polyethylene may be selected as the male member2aand female member2bof the zipper2and polypropylene may be selected as the base material231of the tearing guide strip23.

If the base material231of the tearing guide strip23is in contact with the base film10bon the opposite side in the case of selecting resin materials in this combination, the base material231of the tearing guide strip23is firmly bound with the base film10a(or heat seal layers (not shown) laminated on the base films10aand10b) on the opposite side in the vicinity of the side seal11of the bag1. This makes difficult to tear the base film10aby the tearing guide strip23. In a typical case, this results in that the bag1cannot be unsealed. However, such a disorder can be efficiently avoided by preventing the base material231of the tearing guide strip23from being brought into contact with the base film10bdisposed on the opposite side.

FIG. 5is a sectional view showing the outline of the part corresponding to the section A-A inFIG. 1in the state after the top seal13is provided in the same manner as in the case ofFIG. 2in such an example.FIG. 6shows the state of the bag1unsealed by tearing the part bound with the tearing guide strip23of the base film10a.

Also, in the above embodiment, the tearing guide strip23is disposed on the male member2aside. However, the tearing guide strip23may be disposed on the female member2bside. The tearing guide strip23may be disposed on both the male member2aand the female member2b, so that the bag1can be unsealed from either the surface side (base film10aside) or the backside (base film10bside). Moreover, the positional relationship between the male member2aand the female member2bmay be reversed to that of the example shown inFIG. 2. In this case, the tearing guide strip23is disposed on the female member2bside.

Also, in the above embodiment, the male member2aand female member2bof the zipper2are bound with the base film10aand the base film10brespectively by sealing to thereby fit the zipper2to the bag1. The fitting means of the zipper2is not limited to the above case and for example, the fitting means as shown inFIG. 7may be adopted.

Specifically, the male member2ais bound with the base film10aby heat sealing and the edge of the surface of the base part21bof the extended female member2bon the side provided with the female projection22bmay be fitted by heat sealing to the base film10aat a corresponding position closer to the upper edge side of the bag1than the position of the male member2a.

Such a fitting means enables the content to be filled in the bag1from the between the female member2band the base film10b. Therefore, when the content is filled in the bag1, it is unnecessary to release the interlocking of the zipper2and it is also possible to avoid the adhesion of the content to the interlocking part of the zipper2. Such a fitting means is particularly preferable in a standing bag as shown inFIG. 1which is limited in the port for filling the content.

Here,FIG. 7is a sectional view showing the outline of the part corresponding to the section A-A ofFIG. 1in the state of the bag provided with the top seal13in the same manner as in the case ofFIG. 2. In this example, the top seal13is provided after the content is filled from between the female member2band the base film10b. Also, similarly to the case of the above embodiment, the positional relationship between the male member2aand the female member2bmay be reversed to that of the example shown inFIG. 7. Moreover, like the example shown inFIG. 5, the guide member25may be integrated with the tearing guide strip23such that the gap233is formed between the guide member25itself and the heat seal layer232of the tearing guide strip23. This makes it easy to unseal the bag1more linearly.

Also, the shape of the zipper-equipped bag according to the present invention is not limited to those like standing bags, but may be desired shapes like flat bags and the like as shown inFIG. 8. The bag1shown inFIG. 8is provided with the top seal13on its upper edge and the side seal11along its side edge. After the content is filled from an unsealed part at the lower edge side of the bag1, the lower edge of the bag1is sealed.

FIG. 9is a sectional view along the line B-B ofFIG. 8wherein the tearing guide strip23is disposed on each of the male member2aand the female member2b. However, the tearing guide strip23may be disposed on one of the male member2aand the female member2balso in this example. Also, the relative positional relationship between the male member2aand the female member2bmay be reversed to that of the example shown inFIG. 9.

Moreover, as to each of two tearing guide strips23shown inFIG. 9, like the example shown inFIG. 5, the guide member25may be integrated with the tearing guide strip23such that the gap233is formed between the guide member25itself and the heat seal layer232of the tearing guide strip23. This makes it easy to unseal the bag1more linearly.

Also, the unsealing means of the bag1is not limited to that of the above embodiment. For example, as shown inFIG. 8, paired right and left notches12are disposed on the upper side of the side edge of the bag1and the line connecting these paired notches12is made to accord to the peeling part of the tearing guide strip23so that the tearing of the base films10aand10bof the bag1is initiated by making use of the notch12and these base films10aand10bcan be torn linearly along the longitudinal direction of the zipper2(seeFIG. 10).

Even in the case of adopting such an unsealing means, the tearing guide strip23may be provided on one of the male member and the female member. Also, the notch12may be disposed on only one of the right and left side of the side edge of the bag1if it is situated on the same line as the peeling part of the tearing guide strip23.

Next, a zipper-equipped bag of a second embodiment according to the present invention will be explained.

FIG. 11is a front view showing the outline of the zipper-equipped bag of an embodiment according to the present invention. A bag1shown inFIG. 11is produced by making a bag using base films10aand10bused as a bag base material heat-sealed with a zipper2and is a so-called standing bag which is produced by providing a side seal11along the side edge in the state the bottom part3provided with a bottom seal31is folded along a fold line32.

Also, in the example illustrated, the upper edge of the bag1is unsealed part. After the content is filled, a top seal13is provided.

Here,FIG. 12is a sectional view showing the outline of a part corresponding to the section C-C ofFIG. 11in the state after the top seal13is provided. After the content is filled in the bag1from between a female member2band the base film10b, the top seal13is provided.

The zipper2in this embodiment is constituted of paired male member2aand female member2bas shown inFIG. 12.

The male member2ais provided with a base part21aformed continuously like a tape. A male projection22aconstituted of a head part221aand a connecting part222aconnecting the head part221awith the base part21ais provided on one surface of the base part21aand these parts are integrated. Similarly, the female member2bis provided with a base part21bformed continuously like a tape. A female projection22bconstituted of a pair of hook parts221band221bis provided on one surface of the base part21band these parts are integrated.

In the zipper2constituted like this manner, the head part221aof the male projection22ais fitted in a space formed between the hook parts221band221bof the female projection22b, whereby the male member2aand the female member2bare interlocked with each other. Thereby the takeout port of the bag1can be sealed (resealing) after the bag is unsealed by the zipper2. When the interlocking of the zipper2(interlocking between the male projection22aand the female projection22b) is released, the takeout port of the bag1can be unsealed.

The specific shapes of the male projection22aand female projection22bare not limited to those shown in the figure as long as these projections have fitting shapes which are paired and interlocked with each other.

Also, in the zipper2of this embodiment in the condition that the male member2aand the female member2bare interlocked with each other and fitted to the bag1, the base part21bof the female member2bin the width direction of the base part21bis extended so as to be projected to the side where the top seal13is to be provided, such that the length of the base part21in the width direction is larger than that of the base part21aof the male member2aas shown inFIG. 12. Then, on the surface of the extended part211on the side on which the female projection22bis formed, a tearing guide strip23peelable from the female member2bis integrated along the longitudinal direction of the female member2b.

Here, in the example illustrated, the tearing guide strip23is disposed apart from the edge of the extended part211side of the base part21bof the female member2bto secure its heat seal surface with the base film10aalong the edge of the extended part211side of the base part21bof the female member2b.

When the tearing guide strip23is formed on the base part21bof the female member2b, the peeling strength between the tearing guide strip23and the base part21bis designed to be preferably 15 N/15 mm or less. When the peeling strength exceeds this value, there is a fear that the force required to separate the tearing guide strip23from the base part21bby peeling is increased and it is therefore difficult to obtain a good unsealing feel. Moreover, such a disorder arises that the extended part211is also torn.

Also, although the peeling of the tearing guide strip23may be any of interfacial peeling and cohesive peeling, the former is preferable. The interfacial peeling can prevent peeling scum from being produced on the peeled surface after the tearing guide strip23is separated from the base part21b.

Here, the peeling strength between the tearing guide strip23and the base part21bmeans the largest load found when the both put in a bound state are cut into a test piece having a width of 15 mm and the test piece is subjected to a tensile tester carried out at a measuring atmospheric temperature of 23° C. at a tensile rate of 200 mm/min to peel the both from each other along the direction perpendicular to the direction of the width of the test piece.

Also, in the example illustrate, the tearing guide strip23is provided with a heat seal layer232made of a resin which can be bound with the base film10aby heat sealing on the surface opposite to the binding interface of the base part21bwith the female member2b, namely, on the surface facing the base film10aand the tearing guide strip23is designed to be bound by sufficient binding strength with the part where the base film10ais torn when the bag1is unsealed as will be explained later.

At this time, the binding strength between the base film10aand the tearing guide strip23is preferably made to be larger than the peeling strength between the tearing guide strip23and the female member2b. It is thereby possible to efficiently avoid the peeling of the tearing guide strip23from the base film10aand to allow the peeling of the tearing guide strip23from the base part21bto prevail.

The zipper2in this embodiment which is provided with the tearing guide strip23like this may be fitted to the bag1by binding the surface of the base part21aof the male member2awhich surface is opposite to the surface on which the male projection22ais formed and the surface of the base part21bof the female member2bon which surface the female projection22balong the edge of the extended part211with the same surface of the base film10aby heat sealing. At this time, the tearing guide strip23is also bound with the base film10aby heat sealing.

If the zipper2is fitted to the bag1in this manner, the content can be filled from the space between the female member2band the base film10b. Therefore, when the content is filled in the bag1, it is unnecessary to release the interlocking of the zipper2and it is also possible to avoid the adhesion of the content to the interlocking part of the zipper2. Such a fitting means is particularly effective for a standing bag limited in the port for filling the content as shown inFIG. 11.

Also, if the tearing guide strip23is bound with the base part21bin a freely peelable manner and can be bound with the base film10aby a higher binding strength than the peeling strength from the female member2bby heat sealing, the heat seal layer232may be eliminated as desired.

In this embodiment, the male member2aand the female member2bmay be formed, for example, by extrusion molding of a thermoplastic resin. As the thermoplastic resin, for example, a polyolefin type resin such as polypropylene, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) and an ethylene/methacrylic acid copolymer may be used. The zipper2may have a multilayer structure using plural resins in consideration of the interlocking ability between the male member2aand the female member2b, the sealing strength and heat sealing characteristics of the zipper2with the base films10aand10b.

Also, the same thermoplastic resin made into a film form may be used for the base films10aand10bin consideration of the sealing strength with the zipper2(male member2aand female member2b) and heat sealing characteristics. The base films10aand10bmay have a multilayer structure to allow these films to exhibit various functions as the bag. In this case, for example, the inside layer to be the inside surface of the bag1is formed of the same thermoplastic resin as above as the heat seal layer for the zipper2. Also, biaxially oriented nylon, biaxially oriented polyethylene terephthalate or biaxially oriented polypropylene may be laminated as the outside surface of the bag1, and a barrier layer made of an aluminum foil or an ethylene/vinyl alcohol copolymer film may be laminated as an intermediate layer.

The tearing guide strip23and the heat seal layer232may be integrated with the female member2bsimultaneously when the female member2bis extrusion-molded, for example, by extrusion-supplying the material forming these parts so as to carry out co-extrusion when the female member2bis extrusion-molded.

As the resin forming the tearing guide strip23, a resin incompatible with the resin used for the female member2bmay be selected. For example, in the case of using polyethylene for the female member2b, polypropylene may be used as the resin forming the tearing guide strip23. On the other hand, when polypropylene is used for the female member2b, a polyester resin such as polyethylene terephthalate and polybutylene terephthalate may be used as the resin forming the tearing guide strip23. A modifier may be added properly to these resins, to thereby adjust the peeling strength between the both.

Also, as the resin forming the heat seal layer232, one which has sufficient binding strength with the base film10aand the tearing guide strip23and is resistant to peeling from these materials when the bag1is unsealed is properly selected. For example, when polyethylene is used for the base film10a(or the heat seal layer for zipper2) and polypropylene is used for the tearing guide strip23, metallocene type linear low-density polyethylene may be used. Also, when polypropylene is used for the base film10a(or the heat seal layer for the zipper2) and polybutylene terephthalate is used for the tearing guide strip23, a modified polyolefin type resin such as maleic acid anhydride modified polypropylene or a resin containing the modified polyolefin type resin may be used.

Also, the tearing guide strip23preferably has a higher rigidity than the base part21aof the female member2bto allow itself to be well separated from the female member2bwithout being destroyed by material destruction when it is separated from the female member2band to give no hindrance to tearing of the base film10a. More specifically, the tensile elastic modulus of the tearing guide strip23is preferably 1.3 to 4 times that of the base part21aof the male member2a. At this time, the tensile elastic modulus of the tearing guide strip23is particularly preferably in a range from 300 to 2500 MPa.

When the tensile elastic modulus of the tearing guide strip23exceeds the above range, the tearing guide strip23is broken when the bag is unsealed, leading to such a disorder that the bag is unsealed with difficulty.

On the other hand, when the tensile elastic modulus of the tearing guide strip23is less than the above range, the tearing guide strip23has only insufficient rigidity, causing a hindrance to the peeling from the male member2aor the tearing of the base film10a.

Moreover, such a disorder is caused that the tearing guide strip23is broken and the bag1cannot be unsealed resultantly.

The bag1provided with the zipper2is unsealed by pulling the tearing guide strip23to tear the part of base film10abound with the tearing guide strip23. An unsealing mouth14which is to be a mouth for taking in or out the content is formed at the place left after the above part is torn as shown inFIG. 13and therefore, the content can be taken in or out by releasing the zipper2. Also, if the zipper2is interlocked, the bag1can be resealed and after the bag1is unsealed, the takeout port can be unsealed or sealed by the zipper2.

As mentioned above, the tearing guide strip23is integrated with the extended part211of the base part21bof the female member2balong the longitudinal direction of the extended part211such that it is separated from the female member2bby peeling. Therefore, the bag1is decreased in resistant feel in unsealing and the tearing direction of the base film10acan be guided linearly with a fixed orientation along the longitudinal direction of the zipper2without being disturbed by the male member2a.

Therefore, the bag1is easily unsealed and the unsealing mouth14formed after unsealed is formed in a well shape-reproducible manner and the bag1obtained after unsealed is not resultantly inconvenient in use.

Here, an example of a specific means of tearing the base film10aby the tearing guide strip23to unseal the bag1is shown inFIG. 14.

In the example illustrated, half-cut treatment has been carried out in such a manner as to form a lug12penetrating through a part where the side seal11on which the tearing guide strip23is positioned is formed. It is so devised that at this time, the base film10bforming a part of the lug12is cut off from the other part of the base film10band the base film10aforming a part of the lug12is cut off from a part other than the part torn when the base film10ais unsealed, to form the lug12in the state where the tearing guide strip23is sandwiched between the separated base films10aand10b.

When the lug12is constituted in this manner, the lug12is, as is illustrated, picked up to pull the tearing guide strip23, whereby the base film10ais torn by the tearing guide strip23to form the unsealing mouth14.

In the example illustrated, a part of the base part21bof the female member2bis cut off and put into the state sandwiched between the base films10aand10b. The cut part of the base part21bhas no influence on the unsealing function of the lug12.

According to this embodiment, as mentioned above, the tearing guide strip23is integrated with one of the male member2aand the female member2bsuch that it is separated from the zipper2by peeling. Therefore, a resistant feel is reduced when the bag raw material on the unsealing side against the zipper2is torn to unseal the bag1. Also, since the part where the tearing guide23is disposed is made to project toward the side closer to the unsealing side of the bag1than the other of the male member2aand the female member2b, the tearing guide strip23works so as to guide the direction of tearing with fixed orientation such that the bag raw material is linearly torn along the longitudinal direction of the zipper2without being hindered by the other of the male member2aand female member2b.

Therefore, the bag1is easily unsealed and the unsealing mouth14formed after unsealed is formed in a well shape-reproducible manner and the bag1obtained after unsealed is not resultantly inconvenient in use.

Also, in this embodiment, the following modifications of the embodiment are possible without impairing such effects.

For example, in the above embodiment, the tearing guide strip23is disposed on the female member2bside. However, the tearing guide strip23may be disposed on the male member2aside to thereby reverse the relative positional relationship between the female member2band the male member2ato that of the example illustrated.

Also, in the above embodiment, the male member2aand female member2bof the zipper2are bound with the base film10aby heat sealing to thereby fit the zipper2to the bag1. The fitting means of the zipper2is not limited to the above case.

For example, as shown inFIG. 15, the male member2amay be bound with the base film10aand the female member2bmay be bound with the base film10bby sealing to thereby fit the zipper2to the bag1.

Here,FIG. 15is a sectional view showing the outline of the part corresponding to the section C-C ofFIG. 11in the state of the bag provided with the top seal13in the same manner as in the case ofFIG. 12. In this example, the top seal13is provided in such a manner as to form a predetermined space between the top seal13itself and the zipper2fitted to the upper side of the bag1. Also, similarly to the case of the above embodiment, the relative relationship between the male member2aand the female member2bmay be reversed to the case of the example shown inFIG. 15.

Also, the shape of the zipper-equipped bag according to the present invention is not limited to those like standing bags, but may be desired shapes like flat bags and the like as shown inFIG. 16. The bag1shown inFIG. 16is provided with the top seal13on its upper edge and the side seal11along its side edge. After the content is filled from an unsealed part at the lower edge side of the bag1, the lower edge of the bag1is sealed.

Then, the present invention will be explained in more detail by way of specific examples.

A low-density polyethylene (melting point: 110° C.) having a density of 926 kg/m3and a MFR of 1.5 g/10 min was melt-extruded to extrusion-mold a male member. At the same time, using random polypropylene (melting point 134° C.) having a density of 900 kg/m3and a MFR of 7.0 g/10 min was used as the base material and metallocene type low-density polyethylene having a density of 900 kg/m3and a MFR of 4.0 g/10 min was used as heat seal layer, these raw materials were extrusion-supplied to one end in the width direction of the male member to integrate a tearing guide strip with the male member simultaneously when the male member is molded, thereby obtaining the male member provided with the tearing guide strip. At this time, the heat seal layer of the tearing guide strip was formed 0.6 mm apart from the base part of the male member in such a manner as to form a gap.

A female member provided with a tearing guide strip was molded in the same manner, and a zipper tape provided with paired male member and female member as shown inFIG. 9was obtained.

As to both the male member and the female member, the peeling strength of the binding interface between the tearing guide strip and the base part of the male member or female member was 4 N/15 mm and the tensile elastic modulus of the tearing guide strip was 813 MPa. Also, each base part of the male member and the female member had a tensile elastic modulus of 237 MPa.

The above zipper tape and a base film obtained by dry-laminating a biaxially oriented nylon film (15 μm) and a linear low-density polyethylene film (50 μm) were used to make a bag by a three-way bag machine such that the side of the above zipper tape on which side the tearing guide strip was disposed was located on the unsealing side and the linear low-density polyethylene film side of the above base film was to be the inner surface. Also, a notch was formed on the edge of the bag in such a manner that it is disposed on the same line as the binding part between the zipper tape and the tearing guide strip, to obtain a zipper-equipped bag as shown inFIGS. 8 and 9.

The binding strength between the base film and the tearing guide strip was 30 N/15 mm.

A zipper-equipped bag as shown inFIGS. 1 and 2was obtained in the same manner as in Example 1 except that only the male member was provided with the tearing guide strip and the means shown inFIG. 4was used as the unsealing means.

COMPARATIVE EXAMPLE 1

A zipper-equipped bag was obtained in the same manner as in Example 1 except that the zipper tape was obtained according to the Example 1 of Patent Document 1.

The notch to be formed on the side edge of the bag was positioned on the center in the width direction of the easy cuttable resin layer.

Each zipper-equipped bag obtained in Example 1 and Comparative Example 1 was unsealed by tearing the base films on the both front and back sides from the notch formed on the side edge of the bag and carry out a functional test concerning the tearing resistance at this time. Also, the exposed surface of the zipper tape after the bag was unsealed was observed to evaluate whether cutting scum was present or not.

With regard to the zipper-equipped bag obtained in Example 2, it was subjected to tests to evaluate the tearing resistance and the presence or absence of cutting scum when the lug was picked up to pull the tearing guide strip, thereby tearing the base film with which the tearing guide strip was bound to unseal the bag, in the same manner as above.

The results of evaluation are as follows.

Although the invention has been described in its preferred embodiment, the present invention is not limited to the above first and second embodiments and it should be understood that various changes and modifications may be made within the scope of present invention insofar as the tearing guide strip23is integrated with at least one of the base parts21aand21bof the male member2aand female member2band can be separated from the base parts21aor21bof the male member2aor female member2b.

Then, the bag1equipped with the zipper2like this can be easily unsealed by pulling the tearing guide strip23to tear the bag raw material. Also, the unsealing ability of the bag can be improved because the force required to unseal the bag can be reduced to the utmost by adjusting the binding state of the tearing guide strip23with the base parts21aand21bof the male member2aand female member2b.

Also, in the above first embodiment and second embodiment, the zipper2is bound with the base films10aand10bas the bag raw material by heat sealing when the zipper2is fitted to the bag1. However, an adhesive may be applied to the binding interface between the zipper2and the bag raw material of the tearing guide strip23to bind the zipper2with the bag raw material. If it is so devised that the zipper2is bound with the bag raw material by using an adhesive, even paper having no heat sealing ability may be used as the bag raw material.

In this case, it is not particularly necessary to provide the heat seal layer232in the tearing guide strip23.

Also, in all the above examples, the zipper2is not limited to one having a paired male projection22aand female projection22bas illustrated but may be one having plural paired male projections22aand female projections22b. In this case, plural paired male projections22aand female projections22bare formed on the same base parts21aand21b. Moreover, a zipper which is not provided with the tearing guide strip23is prepared separately from the zipper2provided with the tearing guide strip23and these zippers are fitted to the bag1such that the zipper2provided with the tearing guide strip23is located on the unsealing side.

Industrial Applicability

As explained above, the present invention may be widely utilized for a zipper-equipped bag which is freely sealed and unsealed since it is provided with an interlocking type zipper at the mouth for taking in and out the content.