Patent ID: 12214932

DESCRIPTION OF EMBODIMENT(S)

A detailed description will be made below on preferred exemplary embodiments of the invention with reference to the attached drawings. It should be noted that the same reference sign is used to refer to constituent elements having substantially the same functional configuration and a redundant description thereof is omitted accordingly.

It should be noted that a content of a component of a resin composition is intended as mass % relative to the entire resin composition in the description below unless otherwise specified. In addition, a main component of a resin composition refers to a resin component a content of which is the largest among those of resin components in the entire single-layer resin composition or among layers of a multi-layer resin composition.

First Exemplary Embodiment

FIG.1is a plan view of a zipper-tape-equipped bag according to a first exemplary embodiment of the invention andFIG.2is a cross-sectional view of the zipper-tape-equipped bag taken along a line II-II shown inFIG.1. As shown inFIG.1andFIG.2, a zipper-tape-equipped bag1according to the first exemplary embodiment includes a film10formed into a bag body having a first surface11A and a second surface11B and a zipper tape20.

The film10, which is a container body in this exemplary embodiment, is formed of, for instance, a single-layer or multi-layer thermoplastic resin. More specifically, the film10may include a layer formed of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or polypropylene (PP). PP may be polypropylene homo-polymer (HPP), polypropylene random copolymer (RPP), or polypropylene block copolymer (BPP). In a case where the film10is a multi-layer film, an outer base material may include biaxially oriented polypropylene (OPP), biaxially oriented polyethylene terephthalate (OPET), or biaxially oriented nylon (ONy). Further, the film10may include an inorganic material layer formed by aluminum deposition, stacking aluminum foil layers, or the like. Further, it is preferable that the film10is also provided by a single-layer or multi-layer structure of a biodegradable resin composition in terms of environmental load. As a sealant, a variety of biodegradable resin compositions are usable; for instance, polybutylene succinate (PBS) or poly(butylene succinate/adipate) (PBSA) may be used. Paper (kraft paper) or cellophane may be used as the outer base material.

It should be noted that in this exemplary embodiment, two sheets of the film10are bonded to each other at a bottom seal portion12and a side seal portion13to be formed into the bag body having the first surface11A and the second surface11B; however, a single sheet of the film10may be folded at a portion corresponding to the side seal portion13to provide the first surface11A and the second surface11B in another exemplary embodiment. Alternatively, a portion corresponding to the bottom seal portion12or the side seal portion13in the example inFIG.1may be provided with a so-called gusset, i.e., a portion where the film10is folded inside. In this case, the gusset may be formed from the film10or another film bonded to the film10. Further, the zipper-tape-equipped bag1may be in the form of a stand up pouch that can be placed upright by means of a gusset formed at a bottom portion.

Further, in this exemplary embodiment, the bottom seal portion12and the side seal portion13are formed but no top seal portion is formed, so that an opening14of the zipper-tape-equipped bag1is provided; however, in another exemplary embodiment, with a top seal portion formed in addition to the bottom seal portion12and the side seal portion13, the opening14may be provided afterward in the zipper-tape-equipped bag1by cutting the zipper-tape-equipped bag1between the top seal portion and the zipper tape20. In still another exemplary embodiment, a bag body with no bottom seal portion12formed, that is, the zipper-tape-equipped bag1not sealed opposite the zipper tape20, may be provided. In this case, the bottom seal portion12is formed after contents are packed in the zipper-tape-equipped bag1. In addition to the above, a zipper-tape-equipped container according to the exemplary embodiment of the invention can be provided by bonding a zipper tape to any of bags and containers other than bags having a variety of known configurations as long as the zipper tape is to be welded thereto.

As shown inFIG.2, the zipper tape20is an elongated member, including: in a cross-sectional shape, a pair of base strips21A and21B that are to be bonded respectively to the first surface11A and the second surface11B of the film10; and engagement portions22A and22B projecting from surfaces facing each other of the respective base strips21A and21B and that are engageable with each other. In an example as shown, the engagement portion22A is in a male shape in a cross section and the engagement portion22B is a female shape in a cross section. By engaging these engagement portions22A and22B with each other, the zipper tape20is closed to seal the opening14of the zipper-tape-equipped bag1. It should be noted that shapes of the engagement portions22A and22B are not limited to the male shape and the female shape, and shapes of engagement portions of a variety of known zipper tapes, such as a combination of a claw shape, a hook shape, or a knot shape, are applicable to the engagement portions22A and22B in the above example. Further, although a pair of engagement portions are disposed in the example as shown, a plurality of pairs of engagement portions may be disposed.

In this exemplary embodiment, the base strips21A and21B and the engagement portions22A and22B of the zipper tape20are formed of a biodegradable resin composition having a yield strain of 3.4% or more during a tensile test. Here, the yield strain during the tensile test can be measured according to “JIS K 7161: 2014 Plastics—Determination of tensile properties.” The yield strain is preferably 4% or more, more preferably 5% or more, further preferably 7% or more, much further preferably 10% or more, particularly preferably 15% or more. At a yield strain of 3.4% or more, the zipper tape becomes less plastically deformable and thus suitable for repeated use. The upper limit is usually, but not limited thereto, approximately 30%. Resin compositions with biodegradability, such as resins derived from organic resources or the like and resins derived from petroleum, are usable as the biodegradable resin composition forming the base strips21A and21B and the engagement portions22A and22B. Among the above, the biodegradable resin composition preferably contains at least one of the group consisting of polylactide (PLA), polybutylene succinate (PBS), poly(butylene adipate/terephthalate) (PBAT), polycaprolactone (PCL), poly(caprolactone/butylene succinate) (PCLBS), poly(butylene succinate/adipate) (PBSA), poly(butylene succinate/carbonate) (PEC), poly(ethylene terephthalate/succinate) (PETS), poly(tetramethylene adipate/terephthalate) (PTMAT), polyethylene succinate (PES), polyvinyl alcohol (PVA-H), polyglycolic acid (PGA), and poly (hydroxybutyrate/hydroxyhexanoate) (PHBH), more preferably contains at least one of the group consisting of PLA, PBS, PBAT, and PBSA, preferably contains PBS, PBAT, and PBSA, further preferably contains PBS and PBAT, particularly preferably consists of PBS and PBAT. Even in a case where the biodegradable resin composition consists of PBS and PBAT, inclusion of additives, such as a slip agent, an anti die-drool agent, and an antioxidant, and impurities is acceptable. In addition, the biodegradable resin composition forming the base strips21A and21B and the engagement portions22A and22B may further contain a plasticizer. For instance, glycerin fatty acid ester is usable as the plasticizer.

In a case where the biodegradable resin composition forming the base strips21A and21B and the engagement portions22A and22B contains PBS and PBAT or consists of PBS and PBAT, it is preferable that PBS is in a range from 50 to 99% and PBAT is in a range from 1% to 50%, it is more preferable that PBS is in a range from 60% to 90% and PBAT is in a range from 10% to 40%, and it is further preferable that PBS is in a range from 60% to 80% and PBAT is in a range from 20% to 40%.

In this exemplary embodiment, by means of the base strips21A and21B and the engagement portions22A and22B of the zipper tape20being formed of the biodegradable resin composition as described above, it is possible to improve shape stability and engagement strength of, in particular, the engagement portions22A and22B in spite of the use of the biodegradable resin composition, which is low in environmental load.

It should be noted that although components of the resin composition forming the film10are not limited in the above example, it is preferable that the film10is also provided by a single-layer or multi-layer structure of a biodegradable resin composition in terms of environmental load. In this case, components of a resin composition forming seal surfaces of the base strips21A and21B, that is, surfaces opposite the respective engagement portions22A and22B, are adjusted in accordance with components of a biodegradable resin composition forming a sealant layer of the film10facing the base strips21A and21B of the zipper tape20, for instance, in a manner described below, thereby making it possible to favorably bond the zipper tape20to the sealant layer of the film10.

More specifically, for instance, in a case where the biodegradable resin composition forming the zipper tape20contains 40% to 80% of PBS, the zipper tape20can be favorably bonded to the film10irrespective of whether PLA or PBS is the main component of the biodegradable resin composition forming the sealant layer of the film10. Further, for instance, in a case where the biodegradable resin composition forming the zipper tape20contains 40% or more of PLA, a favorable adhesiveness is achievable as long as the biodegradable resin composition forming the sealant layer of the film10contains PLA as a main component. Further, for instance, in a case where the biodegradable resin composition forming the zipper tape20contains 20% or more of PBS, a favorable adhesiveness is achievable as long as the biodegradable resin composition forming the sealant layer of the film10contains PBS as a main component.

Second Exemplary Embodiment

FIG.3is a cross-sectional view of a zipper-tape-equipped bag according to a second exemplary embodiment of the invention. As shown inFIG.3, a zipper-tape-equipped bag2according to the second exemplary embodiment includes the film10and a zipper tape30. It should be noted that a configuration of the film10is the same as in the above first exemplary embodiment and a redundant description is omitted below accordingly.

The zipper tape30includes second layers312A and312B and first layers311A and311B, the second layers312A and312B including seal surfaces of a pair of base strips that are to be bonded to the respective first surface11A and second surface11B of the film10, the first layers311A and311B including surfaces opposite the seal surfaces of the respective base strips and engagement portions22A and22B. A biodegradable resin composition (a first resin composition) forming the first layers311A and311B including the engagement portions22A and22B is not limited but may be composed, for instance, as in the above first exemplary embodiment. It means that the biodegradable resin composition forming the first layers311A and311B is formed of a biodegradable resin composition having a yield strain of 3.4% or more during a tensile test. The yield strain is preferably 4% or more, more preferably 5% or more, further preferably 7% or more, much further preferably 10% or more, particularly preferably 15% or more. At a yield strain of 3.4% or more, the zipper tape becomes less plastically deformable and thus suitable for repeated use. The upper limit is usually, but not limited thereto, approximately 30%.

Meanwhile, in this exemplary embodiment, although the second layers312A and312B, which include the seal surfaces of the respective base strips of the zipper tape30, may be formed of the same biodegradable resin composition (a first biodegradable resin composition) as the first layers311A and311B, it is preferable that the second layers312A and312B are formed of a biodegradable resin composition (a second biodegradable resin composition) containing different components. Although the second biodegradable resin composition is not limited in terms of components, it is preferable that the second biodegradable resin composition contains, for instance, at least any one of PBS, PBAT, or PBSA. It should be noted that in a case where PBS is contained, the content of PBS may be in a range from 20% to 100%, preferably in a range from 40% to 80%. Alternatively, the second biodegradable resin composition forming the second layers312A and312B may contain any other biodegradable resin, specifically, for instance, PLA, as a main component.

In a case where the biodegradable resin composition (the first biodegradable resin composition) forming the first layers311A and311B contains PBS and PBAT or consists of PBS and PBAT, the components of the biodegradable resin composition (the second biodegradable resin composition) forming the second layers312A and312B may include PBS and PBSA at a desired ratio where PBS is in a range from 0 to 100% and PBSA is in a range from 100 to 0%. It is preferable that the content of PBS is in a range from 0 to 90% and the content of PBSA is in a range from 100 to 10%.

In a case where the biodegradable resin composition (the first biodegradable resin composition) forming the first layers311A and311B contains PBS and PBAT or consists of PBS and PBAT, the components of the biodegradable resin composition (the second biodegradable resin composition) forming the second layers312A and312B may include PBS and PBAT at a desired ratio where PBS is in a range from 0 to 100% and PBAT is in a range from 100 to 0%. It is preferable that the content of PBS is in a range from 0 to 90% and the content of PBAT is in a range from 100 to 10%.

In a case where the biodegradable resin composition (the first biodegradable resin composition) forming the first layers311A and311B contains PBS and PBAT or consists of PBS and PBAT, the components of the biodegradable resin composition (the second biodegradable resin composition) forming the second layers312A and312B may include PBSA and PBAT at a desired ratio where PBSA is in a range from 0 to 100% and PBAT is in a range from 100 to 0%. It is preferable that the content of PBSA is in a range from 0 to 90% and the content of PBAT is in a range from 100 to 10%.

In a case where the biodegradable resin composition (the first biodegradable resin composition) forming the first layers311A and311B contains PBS and PBAT or consists of PBS and PBAT, the components of the biodegradable resin composition (the second biodegradable resin composition) forming the second layers312A and312B may include PBS, PBSA, and PBAT at a desired ratio where PBS is in a range from 0 to 100%, PBSA is in a range from 0 to 100%, and PBAT is in a range from 100 to 0%.

Further, for instance, in a case where the film10is formed of a biodegradable resin composition, the zipper tape30can be favorably bonded to the sealant layer of the film10formed of a biodegradable resin composition (a third biodegradable resin composition) by adjusting components of a resin composition forming a seal surface of the zipper tape30, i.e., the biodegradable resin composition (the second biodegradable resin composition) forming the above second layers312A and312B, as described below.

More specifically, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains 40% to 80% of PBS, the zipper tape30can be favorably bonded to the sealant layer of the film10irrespective of whether PLA or PBS is the main component of the biodegradable resin composition forming the sealant layer of the film10. Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains 40% or more of PLA, a favorable adhesiveness is achievable as long as the biodegradable resin composition forming the sealant layer of the film10contains PLA as a main component. Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains 20% or more of PBS, a favorable adhesiveness is achievable as long as the biodegradable resin composition forming the sealant layer of the film10contains PBS as a main component.

Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains PBSA, the zipper tape30can be favorably bonded to the sealant layer of the film10even though the biodegradable resin composition forming the sealant layer of the film10contains at least one of PBS or PBSA as a main component. Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains PBS, a favorable adhesiveness is achievable as long as the biodegradable resin composition forming the sealant layer of the film10contains at least one of PBS or PBSA as a main component. Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains 10% to 100% of PBSA, the zipper tape30can be more favorably bonded to the sealant layer of the film10even though the biodegradable resin composition forming the sealant layer of the film10contains at least one of PBS or PBSA as a main component. Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains 0% to 90% of PBS, a more favorable adhesiveness is achievable as long as the biodegradable resin composition forming the sealant layer of the film10contains at least one of PBS or PBSA as a main component. Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains 10% to 100% of PBSA and 0% to 90% of PBS, the zipper tape30can be further favorably bonded to the sealant layer of the film10even though the biodegradable resin composition forming the sealant layer of the film10contains at least one of PBS or PBSA as a main component.

Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains PBS and PBAT at a desired ratio where PBS is in a range from 0 to 100% and PBAT is in a range from 100 to 0%, preferably, PBS is in a range from 0% to 90% and PBAT is in a range from 10% to 100%, the zipper tape30can be favorably bonded to the sealant layer of the film10even though the biodegradable resin composition forming the sealant layer of the film10contains at least one of PBS or PBSA as a main component.

Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains PBSA and PBAT at a desired ratio where PBSA is in a range from 0 to 100% and PBAT is in a range from 100 to 0%, preferably, PBSA is in a range from 0% to 90% and PBAT is in a range from 10% to 100%, the zipper tape30can be favorably bonded to the sealant layer of the film10even though the biodegradable resin composition forming the sealant layer of the film10contains at least one of PBS or PBSA as a main component.

Further, for instance, in a case where the biodegradable resin composition forming the second layers312A and312B contains 0 to 100% of PBS, 0 to 100% of PBSA, and 100 to 0% of PBAT, the zipper tape30can be favorably bonded to the sealant layer of the film10even though the biodegradable resin composition forming the sealant layer of the film10contains at least one of PBS or PBSA as a main component.

The zipper tape30is formed by, for instance, coextrusion of the first biodegradable resin composition, which forms the first layers311A and311B including the engagement portions22A and22B, respectively, and the second biodegradable resin composition, which forms the second layers312A and312B including the seal surfaces of the respective base strips. It should be noted that the first layers311A and311B and the respective second layers312A and312B are not necessarily adjacent to each other and one or a plurality of additional layers may be formed between the first layer and the second layer. In this case, the base strips are each divided into a larger number of portions than in the above examples as shown and these portions are formed of respective different biodegradable resin compositions.

Even in this exemplary embodiment, it is also possible to improve the shape stability and engagement strength of the engagement portions22A and22B of the zipper tape30as in the first exemplary embodiment. Meanwhile, by adjusting the components of the biodegradable resin composition forming the seal surfaces of the base strips independently of those of the biodegradable resin composition forming the engagement portions22A and22B, for instance, a bonding performance between the base strips and the film10can be improved. Further, by means of the first and second biodegradable resin compositions containing a common component, for instance, PBS, a bonding performance between the first layers311A and311B and the respective second layers312A and312B can be kept favorable.

It should be noted that in order to prevent unintended biodegradation of the zipper tape from progressing, it is preferable that, for instance, produced zipper tapes are packaged in a manner to be able to block moisture in the first exemplary embodiment and the second exemplary embodiment. Specifically, the zipper tapes may be packaged by means of a packaging material using a stacked body of polyethylene terephthalate (PET), aluminum (AL), and linear low-density polyethylene (LLDPE), a stacked body of aluminum-metallized PET (VMPET), K coated nylon, and linear low-density polyethylene (LLDPE), or a stacked body including biaxially oriented polypropylene (OPP) and non-oriented polypropylene (CPP) respectively as a front surface layer and a back surface layer, or a variety of barrier packaging.

Further, in the first exemplary embodiment and the second exemplary embodiment, it is preferable that a desiccant is enclosed in packaging. Examples of the desiccant include silica gel.

Further, in the first exemplary embodiment and the second exemplary embodiment, a so-called bulk manner in which the zipper tapes are stored and packaged while being dropped and a so-called drum manner in which the zipper tapes are wound on a drum and packaged are both applicable; however, in terms of reducing bending of the zipper tapes due to rigidity thereof, the drum manner is more suitable.

EXAMPLES

Description will be made below on Examples of the invention.

Table 1 shows a relationship between a yield strain and a shape stability during a tensile test with the zipper tape20described above in the first exemplary embodiment, in which the base strips21A and21B and the engagement portions22A and22B were formed of a biodegradable resin composition containing, as a main component, PBS and PLA or PBAT. The shape stability was evaluated as “A” in a case where the yield strain was 6.0% or more and resealing was possible after unsealing and resealing were repeated for 100 times, evaluated as “B” in a case where the yield strain was 3.4% or more and less than 6.0% and resealing was possible after unsealing and resealing were repeated for 100 times, and evaluated as “C” in a case where the yield strain was less than 3.4% or resealing became impossible before unsealing and resealing were repeated for 100 times. Here, the yield strain was measured according to “JIS K 7161: 2014 Plastics-Determination of tensile properties.” Specifically, a test piece was cut out of the base strip of the zipper tape and measured using a tester (manufactured by Shimadzu Corporation, AGS-X 1 kN) complying with JIS K 7161. For measurement, a cross-sectional area was defined as width×thickness of the test piece and a tension rate was set at 300 mm/min. As a result, it has been demonstrated that a yield strain of 3.4% or more during the tensile test provides a shape stability of “B” or higher. It should be noted that a shape stability of “A” is favorable for use as a zipper tape but “B” is also acceptable for some intended use.

It should be noted that the following PBS, PLA, and PBAT were used.PBS (melting point: 115 degrees C. (by DSC method), flexural modulus: 650 MPa (according to ISO 178))PLA (melting point: 160 degrees C. (by DSC method), tensile modulus: 4500 MPa (according to ISO 527))PBAT (melting point: 110 to 120 degrees C. (by DSC method), tensile modulus: 80 MPa (according to ISO 527))

TABLE 1Table 1: Shape Stability and YieldStrain in Examples and ComparativeShapePLA(%)PBS(%)PBAT(%)StabilityYield Strain (%)Comp. 110000C3.3Ex. 170300B4.0Ex. 250500B4.0Ex. 330700B4.0Ex. 420800A8.0Ex. 510900A11.5Ex. 601000A12.6Ex. 709010A15.8Ex. 807030A16.6

Next, regarding the zipper tape30described above as the second exemplary embodiment, Table 2 shows a result of measurement of a sealing strength between the biodegradable resin composition (the second biodegradable resin composition) forming the second layers312A and312B including the seal surfaces of the respective base strips and the biodegradable resin composition (the third biodegradable resin composition) forming the sealant layer of the film10. Specifically, an evaluation sample, in which layers formed of the respective resin compositions were stacked and sealed for a sealing time of 1.0 second, at a sealing pressure of 2.0 MPa, and at a sealing temperature of 180 degrees C., was subjected to measurement of an interlayer heat sealing strength per width of 15 mm (N/15 mm) by using “Digital Force Gauge” manufactured by IMADA CO., LTD. It should be noted that with a tension rate during the sealing strength measurement set at 300 mm/min, a sealing strength of 20 (N/15 mm) or more is shown as “A” and a sealing strength less than 20 (N/15 mm) is shown as “C” in Table 2.PBS (melting point: 115 degrees C. (by DSC method), flexural modulus: 650 MPa (according to ISO 178))PLA (melting point: 160 degrees C. (by DSC method), tensile modulus: 4500 MPa (according to ISO 527))PBAT (melting point: 110 to 120 degrees C. (by DSC method), tensile modulus: 80 MPa (according to ISO 527))PBSA (melting point: 84 degrees C. (by DSC method), tensile modulus: 250 MPa (according to ISO 527))

TABLE 2Table 2: Sealing Strength between Film and Base Strip (1)Sealant Layer of FilmMainMain ComponentPLAPBSComponentPLA(%)/PBS(%)100/080/2060/4040/6020/800/100SealPLA100/0AAAACCSurface80/20AAAACCof Base60/40AAAAAAStripPBS40/60AAAAAA20/80AAAAAA0/100CAAAAA

TABLE 3Table 3: Sealing Strength between Film and Base Strip (2)Sealant Layer of FilmMainMain ComponentComponentPBS(%)/PBSA(%)PBSPBSASealPBS100/0BBSurfacePBS80/20AAof BasePBS60/40AAStripPBSA40/60AAPBSA20/80AAPBSA0/100AA

TABLE 4Table 4: Sealing Strength between Film and Base Strip (3)Sealant Layer of FilmMainMain ComponentComponentPBS(%)/PBAT(%)PBSPBATSealPBS70/30BBSurfaceof BaseStrip

It has been demonstrated from the result shown above in Table 2 that in a case where the biodegradable resin composition forming the seal surfaces of the base strips contains 40% to 80% of PBS, a favorable sealing strength is achievable irrespective of whether the biodegradable resin composition forming the sealant layer of the film10contains PLA or PBS as a main component. Further, it has been demonstrated that in a case where the biodegradable resin composition forming the seal surfaces of the base strips contains 40% or more of PLA, a particularly favorable sealing strength is achievable as long as the biodegradable resin composition forming the sealant layer of the film10contains PLA as a main component. Further, it has been demonstrated that in a case where the biodegradable resin composition forming the seal surfaces of the base strips contains 20% or more of PBS, a particularly favorable sealing strength is achievable as long as the biodegradable resin composition forming the sealant layer of the film10contains PBS as a main component.

Further, it has been demonstrated from the result shown above in Table 3 that in a case where the biodegradable resin composition forming the seal surfaces of the base strips is a mixture containing PBS and PBSA at a desired ratio, a favorable sealing strength is achievable irrespective of whether the biodegradable resin composition forming the sealant layer of the film10contains PBS or PBSA as a main component. Further, it has been demonstrated from the result shown above in Table 3 that by means of combined use of PBS and PBSA as the biodegradable resin composition forming the sealant layer of the film10, a more favorable sealing strength is achievable as compared with in a case where the biodegradable resin composition consists of PBS.

Further, it has been demonstrated from the result shown above in Table 4 that in a case where the biodegradable resin composition forming the seal surfaces of the base strips is a mixture containing PBS and PBAT at a desired ratio, a sealing strength comparable to that in a case where the biodegradable resin composition consists of PBS as shown in Table 3 above is achievable.

The preferred exemplary embodiments of the invention are described above in detail with reference to the attached drawings; however, the invention is not limited to these examples. It is obvious to those skilled in the art to which the invention pertains that a variety of modifications or alterations are conceivable within the scope of the technical idea according to claims and it should be understood that these are also, of course, within the technical scope of the invention.