JP4571835B2 - Coextruded composite film for lid of distribution package - Google Patents

Description

  The present invention relates to a lid for a dispensing package. The “distribution package” in the present invention refers to, for example, jam, ketchup, sauce, paste, etc. on the bottom material 1 formed by deep drawing a soft film as shown in FIG. It is a package 200 obtained by containing a food having a good viscosity and fluidity and sealing the opening of the bottom material 1 with the lid material 2 of the present invention. The lid member 2 of the present invention is provided with a convex portion 3 that protrudes to the outside of the package 200, and a half cut 4 is formed on the surface portion of the lid member 2 so as to be orthogonal to the longitudinal direction of the convex portion 3. When the lid 2 of the package 200 is bent in the direction of the bottom 1, the bending stress is concentrated on the convex portion 3, the convex portion 3 is torn along the half cut 4, and the lid 2 is opened. Further, by pushing the lid material 2 so that the left and right sides of the lid member 2 are in close contact with each other, a fluid food or the like contained in the bottom member 1 is discharged from the opening by the pressing force of the lid member 2. Therefore, according to the distribution package 200, the contents inside the package 200 can be pushed out in the direction desired by the user without making the hands dirty, by a simple operation of bending the lid member 2 and crushing it as it is. it can. The basic configuration of such a package is disclosed in Patent Document 1.

Conventionally, the lid of the distribution package has been formed by using vinyl chloride (hereinafter referred to as “PVC”) as a plastic sheet, and bonding the PVC sheet and a co-extruded composite film by a dry lamination method or the like. The body was used suitably (refer patent document 2). An example of the layer structure of such a laminate is shown below.
(Table printing) PVC sheet // co-extruded composite film (EVOH layer / Ny layer / PE layer / seal layer)

  In the above layer configuration, the “seal layer” refers to a layer that forms a joint surface with the bottom material in the lid of the distribution package. The “sheet” means a sheet-like member prepared separately from the coextruded composite film. In addition, the notation “//” in the above layer configuration indicates that the layers described before and after that are bonded by a dry lamination method, and “/” indicates that the layers described before and after that are bonded by a coextrusion method. It shows that it is joined. The same notation is used in the following. “EVOH” means a saponified ethylene-vinyl acetate copolymer resin, and “Ny” means a polyamide resin.

  This Ny layer is indispensable for maintaining the melt tension in forming the coextruded composite film to 20 to 100 μm. On the other hand, since the Ny layer is tough, if it is used for a part of the layer structure, the openability may be adversely affected. However, in the above layer structure, there is no problem in the openability of the package because PVC is easily cracked (hereinafter referred to as “easy cracking”).

On the other hand, due to environmental problems in recent years, vinyl chloride may generate chlorinated gas, which is considered harmful during waste incineration, so vinyl chloride is especially avoided by the food industry, and alternative materials are required. Yes. As a layer structure not using such vinyl chloride, for example,
Stretched substrate (back printing) // PS sheet // Co-extruded composite film (EVOH layer / Ny layer / adhesive layer / seal layer)
(See Patent Document 3). Here, “PS” means polystyrene resin. In this configuration, printing is performed on a stretched substrate, dry-laminated with a PS sheet, and a co-extruded composite film is dry-laminated for the purpose of providing an oxygen barrier and sealing properties.
JP 59-103866 A JP-A-64-37370 JP-A-3-256862

Conventional (front printing) PVC sheet // co-extruded composite film (EVOH layer / Ny layer / PE / seal layer) using vinyl chloride
In the configuration, even if the Ny layer is included in the co-extruded composite film, the PVC sheet is easily cracked and easily cracked, so that the stress from the PVC sheet directly propagates to the co-extruded film side, and the As a result, there was no problem with the openability. However, since the PVC sheet is usually subjected to surface printing, there is a problem that printing is lost due to friction when a hard food (for example, dry noodles) and this package are packaged and transported. Furthermore, the printing pitch was not stable, and troubles with the packaging machine occurred frequently.

  Also, in the case of a layered product that does not use vinyl chloride, even if the layered structure uses a PS sheet with relatively good cracking properties instead of the PVC sheet, if the Ny layer is present in the composite film, the package is bent with a finger and opened. In this case, the PS sheet breaks, but the bonded composite film may be stretched but not opened. Therefore, in order to stabilize the printing pitch and from the viewpoint of convenience and hygiene that can store the original printing fabric, back printing is applied to a stretched base material (for example, stretched Ny (ONy), stretched PET (OPET)), and a PS sheet. Although the above problem has been solved by dry-laminating, the moldability of the stretched substrate is not so good, and there are also problems that the cost is high because the number of times of lamination is two.

  Therefore, an object of the present invention is to provide a coextruded composite film for a lid of a distribution package that has good openability, good moldability and printability, and low production costs.

  The present invention has found a coextruded composite film for a lid of a distribution package that can solve the above-mentioned problems, and the above object can be achieved by the following means. In the present invention described below, the “surface layer” refers to a layer having a surface opposite to the side bonded to the bottom material in the coextruded composite film for the lid of the distribution package. The “sealing layer” refers to a layer constituting a joint surface with the bottom material in the coextruded composite film for a lid of the distribution package. The “intermediate layer” refers to a layer sandwiched between the surface layer and the seal layer. Furthermore, the “main constituent layer” refers to a layer having the largest layer thickness in the coextruded composite film for a lid of the distribution package.

  A first aspect of the present invention is a coextruded composite film for a lid of a distribution package in which a surface layer, an intermediate layer, and a seal layer are laminated in this order, and the surface layer is composed of at least one copolyester resin layer. The intermediate layer is a polystyrene resin (hereinafter referred to as “PS”) layer, at least one adhesive layer, and an ethylene-vinyl acetate copolymer saponified resin (hereinafter referred to as “EVOH”) having an ethylene content of 29 to 47 mol%. The sealing layer is composed of at least one polyethylene-based resin (hereinafter referred to as “PE”) layer, and the PS layer is the main constituent layer. It is a film.

  According to the present invention, it is possible to provide a coextruded composite film for a lid of a distribution package having good openability, good moldability and printability, and low production cost. Moreover, coextrudability and film strength of the coextruded composite film for a lid of the distribution package can be improved by maintaining the ethylene content of EVOH within the above range. Moreover, since a composite film can be produced at a stretch by a single coextrusion step, it is possible to provide a coextruded composite film for a lid of a distribution package at a low production cost.

  In the first aspect, the intermediate layer is preferably laminated in the order of the PS layer, the adhesive layer, and the EVOH layer from the surface layer side.

  In this way, even if a cut is made in the PS layer from the surface layer side, the EVOH layer disposed therebelow is not cut, so that the oxygen barrier property is not impaired.

  Moreover, in the said aspect, thickness ratio of EVOH layer, PE layer, PS layer, and a copolyester-type resin layer is 1-7.5: 1.5-70: 25-350: 2.5-35. Is preferred.

  When comprised in this way, while being good as a lid | cover material of a distribution package, while being able to obtain oxygen barrier property, intensity | strength, openability, and the adhesiveness between each layer, a process can be made easy.

  Moreover, in the said aspect (a modification is included), each layer is a PE layer, an adhesion 1st layer, an EVOH layer, an adhesion 2nd layer, PS layer, an adhesion 3rd layer, a copolymerization polyester system resin layer from the seal layer side. It is preferable to laminate in order.

  In this way, in the present invention, since the EVOH layer is disposed adjacent to the PS layer (main constituent layer) having the largest layer thickness via the adhesive layer, the adhesive strength between the two is kept within a predetermined range. Thus, it becomes easy to obtain a good opening behavior. Moreover, since the copolyester resin layer is arranged on the surface layer side, good printability and printing stability can be obtained.

  In the above modification, the thickness ratio of the EVOH layer, the first adhesive layer, the second adhesive layer, and the third adhesive layer is 1 to 7.5: 2.5 to 15: 2.5 to 15: 2.5 to 25 It is preferable that

  If it does in this way, the adhesive strength between each layer of PE layer, EVOH layer, PS layer, and a copolyester-type resin layer can be maintained in a favorable range.

  In the above aspects (including modifications), the total thickness of each layer is preferably 75 to 1035 μm.

  In this way, the product value as a distribution package is maintained with an appropriate film stiffness and tactile sensation without impairing the good opening properties and composite film moldability of the distribution package. be able to.

  Moreover, in the said aspect (each modification is included), it is preferable that PE layer is comprised by PE 1st layer and PE 2nd layer which consist of the same kind or a different component.

  Thus, by making PE layer into a two-layer structure, the film | membrane cutting property required for unsealability with a crack of PS layer can be made favorable, maintaining favorable sealing property.

  Moreover, in the said aspect (each modification is included), it is preferable that PE is a low density polyethylene (LDPE), a high density polyethylene (HDPE), or these mixtures.

  By adopting such a configuration, it is possible to freely control the blending ratio of LDPE and HDPE, and to adjust the cracking property generated in the lid material when opening the package and the adhesive strength with EVOH. Further, by blending the two, a lid material excellent in a property (hereinafter referred to as “easy cracking property”) that can be easily cracked at the time of opening with HDPE while increasing the melt tension by LDPE to stabilize the film forming property. It becomes possible.

  Moreover, in the said aspect (each modification is included), it is preferable that PS is the single-piece | unit of the compounded product of general purpose polystyrene (GPPS), an impact-resistant polystyrene (HIPS) butadiene type compound, or these mixtures.

  If it does in this way, the cracking property which arises in the cover material at the time of opening a distribution package can be freely set by controlling a compounding ratio appropriately.

  Moreover, in the said aspect (each modification is included), it is preferable that the adhesive strength of PS layer and EVOH layer is 3.9-15N / 15mm.

  By making the adhesive strength between the PS layer and the EVOH layer within the above range, when the flowable food contained in the package is distributed, the PS layer is cracked and then the seal layer is extended from the EVOH layer, and the center part is extended. Since the opening is gradually opened after tearing, the opening behavior is good, and the fluid substance as the contents can be discharged toward the target as intended.

  A second aspect of the present invention is a lid for a distribution package formed by any of the coextruded composite films according to the first aspect.

  According to the cover material concerning this aspect, it is possible to provide the distribution package provided with the characteristics of the coextruded composite film according to the first aspect.

  A third aspect of the present invention is a distribution package using the lid according to the second aspect.

  According to the distribution package according to this aspect, it is possible to provide the distribution package having the characteristics of the lid according to the second aspect.

  According to the present invention, it is possible to provide a coextruded composite film for a lid of a distribution package having good openability, good moldability and printability, and low production cost. Such an operation and a gain of the present invention will be clarified from the best mode for carrying out the invention described below.

  FIG. 1 is a view showing a cross section of a coextruded composite film for a lid of a distribution package according to an embodiment of the present invention. A lidding coextruded composite film 100 of the illustrated distribution package is a coextruded composite film in which a surface layer 10, an intermediate layer 11, and a seal layer 12 are laminated in this order. The surface layer 10 is formed of a copolyester resin layer 13. The intermediate layer 11 includes, from the surface layer side, an adhesive third layer 14, a polystyrene resin (PS) layer 15, an adhesive second layer 16, an ethylene-vinyl acetate copolymer saponified resin having an ethylene content of 29 to 47 mol% ( EVOH) layer 17 and adhesive first layer 18 are laminated in this order. Further, the sealing layer 12 includes a polyethylene resin (PE) second layer 19 and a PE first layer 20 from the surface layer side. The co-extruded composite film 100 for a lid of a distribution package having such a layer structure is characterized in that the PS layer 15 forms the thickest layer (main component layer). In the present embodiment, the sealing layer 12 has a two-layer structure of a PE second layer 19 and a PE first layer 20.

(PE layer)
In the coextruded composite film for the lid of the distribution package of the present invention, it is essential to have at least one PE layer, but as in the above embodiment, a multilayer structure of PE first layer and PE second layer. It is preferable that It is preferable to use LDPE, HDPE, or a blend of LDPE and HDPE for the PE layers 19 and 20 having such a two-layer structure. In determining the blend ratio, the following considerations should be made while considering the layer thickness. That is, the PE first layer 20 that forms the outermost layer of the seal layer 12 preferably has a high LDPE blending ratio in order to ensure sealability and appropriate openability. On the other hand, the PE second layer 19 on the intermediate layer 11 side needs to propagate the “cut” of the layer (film) well with the crack of the PS layer 15 as the main constituent layer. It is also preferable to blend. The mixing ratio of LDPE and HDPE is 40-80: 60-20, preferably 50-80: 50-20, and more preferably 60-80: 40-20 by mass ratio. By adopting such an arrangement, it is possible to freely control the blending ratio of LDPE and HDPE, and to adjust the cracking property generated in the lid material when opening the package and the adhesive strength with EVOH. Also, by blending the both, the melt tension is increased by LDPE to stabilize the film forming property, and a lid material excellent in the property of being easily cracked at the time of opening with HDPE (hereinafter referred to as “easy to crack”) is obtained. It becomes possible.

  LDPE having a density of 0.92 or more is preferable, and HDPE having a density of 0.95 or more is preferably used. By increasing the density, it is possible to impart good tearability to the PE layer. The thickness of the PE second layer 19 of the seal layer 12 is preferably 2 to 70 μm. More preferably, it is 3-20 micrometers, Most preferably, it is 5-10 micrometers. By keeping the thickness of the PE second layer 19 of the sealing layer 12 in the above range, it becomes possible to keep the cut of the PE layer at the time of opening well. Moreover, it is preferable that the thickness of the PE 1st layer 20 which comprises the sealing layer 12 is 2-70 micrometers. More preferably, it is 3-20 micrometers, Most preferably, it is 5-10 micrometers. By defining the thickness of each PE layer in this manner, it becomes possible to maintain good sealing properties while maintaining good cutting at the time of opening.

(EVOH layer)
The EVOH layer 17 in the coextruded composite film 100 for a lid of a distribution package according to an embodiment of the present invention has a function as an oxygen barrier layer. In the present invention, EVOH must have an ethylene content of 29 to 47 mol%. Preferably, the ethylene content of EVOH is 32 to 44 mol%. The saponification degree of EVOH is preferably 90 mol% or more, more preferably 95 mol% or more. By maintaining the ethylene content of EVOH and the saponification degree within the above ranges, the coextrusion property and film strength of the coextruded composite film for the lid of the distribution package can be improved. The thickness of the EVOH layer 17 is preferably 2 to 15 μm, more preferably 3 to 12 μm, and particularly preferably 5 to 10 μm. If the EVOH layer 17 is too thin, it becomes difficult to maintain good oxygen barrier properties. On the other hand, if the EVOH layer 17 is too thick, the coextrudability of the film deteriorates, which is disadvantageous in maintaining the film strength.

(Adhesive layer)
In the present invention, the resin constituting the first adhesive layer to the third layer 14, 16, 18 is a PE second layer 19 and EVOH layer 17, EVOH layer 17 and PS layer 15, and PS layer 15 and copolymer polyester resin. Although it will not specifically limit if the layer 13 can be adhere | attached to required intensity | strength, The polyolefin resin modified with unsaturated carboxylic acid or its derivative (s) is used suitably. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid and the like. Moreover, ester and anhydride of these unsaturated carboxylic acids can also be used. Furthermore, examples of the derivatives include methyl acrylate, methyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, butyl methacrylate, vinyl acetate, glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, sodium acrylate, and the like. . For example, the product name Admer manufactured by Mitsui Chemicals, Inc. is commercially available and is preferably used. Among these, in the case of adhesion between the copolyester resin layer 13 and the EVOH layer 17 and the PS layer 15, those based on polyolefin are useful. In the case of adhesion between the EVOH layer 17 and the PE second layer 19, a linear low density polyethylene (hereinafter referred to as “LLDPE”) type is preferably used.

  The thickness of the adhesive first layer 18 and the adhesive second layer 16 disposed between the PE second layer 19 and the EVOH layer 17 and between the EVOH layer 17 and the PS layer 15 should be 5 to 30 μm. Is preferred. More preferably, it is 8-20 micrometers, Most preferably, it is 10-15 micrometers. By setting the thickness of the adhesive layers 18 and 16 within the above range, the adhesive strength between the EVOH layer 17 and the PS layer 15 can be maintained in a favorable range. The thickness of the adhesive third layer 14 between the PS layer 15 and the copolyester resin layer 13 is preferably 5 to 50 μm, more preferably 8 to 30 μm, and particularly preferably 10 to 10 μm. 20 μm. If the thickness of the adhesive third layer 14 is too thin, the adhesive strength between the PS layer 15 and the copolyester resin layer 13 cannot be maintained in a favorable range. On the contrary, if the thickness of the adhesive third layer 14 is too thick, it is disadvantageous from the viewpoint of economy.

(PS layer)
As the polystyrene resin constituting the PS layer 15 constituting the coextruded composite film for the lid of the distribution package of the present invention, general-purpose polystyrene (hereinafter referred to as “GPPS”) and impact-resistant polystyrene (hereinafter referred to as “HIPS”). ), Styrene / butadiene block copolymer (butadiene compound), or a blend thereof. GPPS does not contain a rubber component and is very easy to break. On the other hand, since HIPS is blended with a rubber component, it has a property that it is difficult to break. Therefore, by appropriately controlling the blend ratio of GPPS and HIPS, it is possible to adjust the cracking property generated in the lid material when the package is opened.

For GPPS, a heat-resistant grade having a flexural modulus of 3,200 to 3,300 MPa and a Charpy impact strength (notched) of 1.5 to 3.0 KJ / m ² is preferably used. Meanwhile, HIPS is flexural modulus 2,100～2,500MPa, Charpy impact strength (with notch) is high impact grade is preferably used in 13~16KJ / ^{m 2.} Examples of styrene / butadiene block copolymers include Asaflex, Tuffprene and Asaprene manufactured by Asahi Kasei Corporation. These melt flow rates are preferably 5 g / 10 min [200 ° C., 5 kg] or more. By setting the melt flow rate within the above range, it becomes easy to ensure good coextrusion properties. Here, “melt flow rate (melt flow index): solution flow rate” is one of the measures indicating the fluidity of a polymer in a solution state, and is also referred to as “solution index”. The amount flowing out from a nozzle (orifice) having a prescribed size under a constant pressure and a constant temperature is measured with an extrusion type plastometer and expressed in units of g / 10 min. In general, the larger the melt flow rate, the better the fluidity and workability during melting, but the lower the tensile strength and stress cracking resistance. See ISO 1133 “Plastics—Measuring melt flow rate of thermoplastics” for specific measurement methods.

  The thickness of the PS layer 15 is preferably 50 to 700 μm, more preferably 200 to 500 μm, and particularly preferably 250 to 350 μm. If the thickness of the PS layer 15 is too thin, it will be difficult to obtain good openability when used as a lid for a distribution package. On the other hand, if the thickness of the PS layer 15 is too thick, it is difficult to open easily, and the commercial value as a distribution package decreases.

(Copolymerized polyester resin layer)
In the co-extruded composite film 100 for a lid of a distribution package according to an embodiment of the present invention, the copolyester resin layer 13 is disposed on the outermost layer side. By adopting such a configuration, it becomes possible to utilize the good printability and print stability of the copolyester resin. In addition, in one Embodiment of this invention, although the copolyester-type resin layer 13 is described as one layer, it can also be formed with two or more layers which consist of the same kind or different component.

  The copolymerized polyester resin used in the copolymerized polyester resin layer 13 is a polyester resin in which 5 mol% or more of 1,4-cyclohexanedimethanol component is contained in 100 mol% of the polyhydric alcohol component, and is an amorphous polyester resin. It is preferable that The copolyester resin desirably contains a 1,4-cyclohexanedimethanol component in an amount of 10 mol% or more, preferably 12 mol% or more, more preferably 15 mol% or more from the viewpoint of increasing the degree of non-crystallinity. On the other hand, if the 1,4-cyclohexanedimethanol component is too much, the impact strength of the film will decrease, so the upper limit is preferably 50 mol%, more preferably 47 mol% or less, and 45 mol. % Or less is more preferable.

  Considering the heat resistance and printing characteristics of the distribution package, the ethylene terephthalate unit is 50 mol% or more, preferably 55 mol% or more, more preferably 60 mol% or more in 100 mol% of the unit constituting the copolyester resin. It is desirable to select such that Therefore, 50 mol% or more of terephthalic acid component (component formed from terephthalic acid or its ester) in 100 mol% of polyvalent carboxylic acid component, and 50 to 95 mol of ethylene glycol component in 100 mol% of polyhydric alcohol component %, Preferably 55 to 90 mol%, more preferably 60 to 88 mol%.

  Examples of the polyhydric alcohol for forming the polyhydric alcohol component include 1,3-propanediol, triethylene glycol, 1,4-butanediol in addition to the above-mentioned 1,4-cyclohexanedimethanol and ethylene glycol. 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9 -Alkylene glycols such as nonanediol, 1,10-decanediol, trimethylolpropane, glycerin, pentaerythritol, diethylene glycol, dimer diol, polyoxytetramethylene glycol, polyethylene glycol, bisphenol compounds or derivatives thereof Ido adducts such as can also be used in combination.

  In addition to the above-mentioned terephthalic acid and its esters, aromatic dicarboxylic acids, their ester-forming derivatives, aliphatic dicarboxylic acids, etc. can be used as the polyvalent carboxylic acids for forming the polyvalent carboxylic acid component. is there. Examples of the aromatic dicarboxylic acid include isophthalic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, and 5-sodium sulfoisophthalic acid. Moreover, derivatives of these aromatic dicarboxylic acids and terephthalic acids include derivatives such as dialkyl esters and diaryl esters. Examples of the aliphatic dicarboxylic acid include glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, succinic acid and the like, and an aliphatic dicarboxylic acid usually called dimer acid. Further, an oxycarboxylic acid such as p-oxybenzoic acid, and a polyvalent carboxylic acid such as trimellitic anhydride or pyromellitic anhydride may be used in combination as necessary.

  In addition, although not polyhydric alcohols or polycarboxylic acids, lactones represented by ε-caprolactone may be used in part. Lactones are those that ring-open to become units having ester bonds at both ends, and a unit derived from one lactone can be considered to be a carboxylic acid component and an alcohol component. Therefore, when lactones are used, the amount of 1,4-cyclohexanedimethanol component and the amount of other polyhydric alcohol components are the total amount of polyhydric alcohol components of the film plus the unit amount derived from lactones. Calculated as 100 mol%. Also, when calculating the amount of each polycarboxylic acid component, the amount obtained by adding the unit amount derived from the lactone to the total polycarboxylic acid component amount of the film is 100 mol%. For example, a polyethylene terephthalate resin in which the diol component is composed of 1,4-cyclohexanedimethyl alcohol and ethylene glycol and the dicarboxylic acid component is composed of terephthalic acid can be suitably used as an amorphous polyester resin (PETG).

  The thickness of the copolyester resin layer 13 is preferably 5 to 70 μm, more preferably 8 to 50 μm, and particularly preferably 10 to 40 μm. If the thickness of the copolyester-based resin layer 13 is too thin, the surface strength of the coextruded composite film 100 for the lid of the distribution package is lowered, and the printing layer is dropped from the film together with the copolyester-based resin layer 13. . On the other hand, when the thickness of the copolyester resin layer 13 is too thick, adjustment of the cut to be put in the PS layer 15 tends to be difficult.

(Total film thickness)
Thus, the total thickness of the layers constituting the surface layer 10, the intermediate layer 11, and the sealing layer 12 is preferably about 75 to 1035 μm, more preferably 240 to 670 μm, and particularly preferably 300 to 470 μm. If the total thickness of the film is too thin, the feel of the film is weakened and the commercial value as a distribution package is reduced. On the other hand, if the total thickness of the film is too thick, it is economically disadvantageous and the film feels hard, and in this case as well, the commercial value as a distribution package decreases.

(Openability)
As a factor affecting the openability,
(1) Cracking property of PS layer 15 (2) Interlayer adhesion strength between PS layer 15 and EVOH layer 17 (3) Three factors of PE second layer 19 and PE first layer 20 are tearable and thickness. The PS layer 15 can make breaks (half cuts) in a straight line in the cracking direction in parallel to the thickness direction, thereby improving the propagation of cracks.

  (1) The crackability of the PS layer 15 varies depending on the blend ratio of PS. Increasing the GPPS ratio is easier to crack, and conversely increasing the HIPS ratio makes it difficult to crack. The crackability can be adjusted by this blend ratio.

  (2) The higher the interlayer adhesive strength between the PS layer 15 and the EVOH layer 17, the better. When the lid material is folded and opened, the main layer of the coextruded composite film 100 is peeled off when the interlayer (adhesive layer 16) peels off. Layers other than the PS layer 15 that is a constituent layer are stretched, causing troubles that do not cut well and do not open. That is, the PS layer 15 as the main constituent layer is cracked, while the coextruded composite film of the other part is a phenomenon that is not stretched but is stretched without being cut. Controlling the adhesive strength to 3.9 to 15 N / 15 mm width is suitable for opening. Therefore, when the EVOH layer 17 is disposed via the PS layer 15 as the main constituent layer and the adhesive second layer 16, the adhesive strength can be maintained at a width of 3.9 to 15 N / 15 mm. The PS layer 15 is cracked, and the remaining coextruded composite film is stretched while being stretched, and the opening is gradually opened from the center. For this reason, it becomes a favorable opening behavior, and enables the fluid substance as the contents to be discharged toward the target as intended. Therefore, it is preferable to control the interlayer adhesive strength between the PS layer 15 and the EVOH layer 17 to a width of 3.9 to 15 N / 15 mm. More preferably, the width is 6 to 12 N / 15 mm. The interlaminar adhesive strength can be determined by measuring the maximum load when a coextruded composite film having a width of 15 mm is peeled off at a normal temperature at a tensile rate of 200 mm / min. If it is lower than the appropriate value, peeling (delamination) occurs and the PS layer 15 breaks, but the seal layer 12 does not tear from the EVOH layer 17 and does not open, and the contents do not discharge. Also, if the value is higher than the appropriate value, the opening will follow the cracking direction of the PS layer 15, and when the contents pop out, the opening will not be determined and the phenomenon will occur in a direction different from the target. End up.

  (3) With respect to the tearability of the PE second layer 19 and the PE first layer 20, the tearability can be adjusted with LDPE, HDPE, or a blend of LDPE and HDPE. Higher density PE has better tearability. In order to fly the fluid substance, which is the contents described in (2), toward the target, it is necessary to adjust the elongation and tearability by the blend.

(Printability)
Regarding printing, conventionally, surface printing or printing on a printing substrate and dry lamination have been performed. Here, the printing substrate is amorphous unstretched PET (APET), stretched PET (OPET), crystalline PET (CPET), stretched PP (OPP), unstretched PP (CPP), polybutylene terephthalate (PBT). , Stretched Ny (ONy), non-stretched Ny (CNy), polyethylene naphthalate (PEN), stretched PS (OPS), and the like. Among these, there is no particular limitation as long as it can be molded and has pitch stability.

  In addition, the problem of blurring of printing due to friction with contents and printing pitch stability that occurred in front printing was solved by backing printing on the printing substrate and dry laminating to the PS layer side, The number of laminations increased and the cost was high. Therefore, in the present invention, a copolyester resin, which is a resin having good printability and print stability, is disposed on the printing surface. Furthermore, if necessary, another layer of clear color solid coating is applied from the top of the printing surface to improve the stability of the printed film, reduce printing layer slipping, etc., and maintain hygiene. It becomes.

These are one embodiment of the present invention.
PE first layer 20 / PE second layer 19 / bonded first layer 18 / EVOH layer 17 / bonded second layer 16 / PS layer 15 / bonded third layer 14 / copolymerized polyester resin layer 13
According to the coextruded composite film 100 for a lid material of a distribution package having a layer structure made of the above, the printability of the copolymerized polyester-based resin layer 13 and, if necessary, clear printing is applied with a solid color so that the print layer Can stabilize and improve hygiene. In addition, the distribution package is smoothly opened by the easy cracking of the PS layer 15 formed by appropriately blending GPPS and HIPS, the easy tearing from the EVOH layer 17 to the sealing layer 12, and the aiming of the opening. Sex will be obtained. Furthermore, the PE second layer 19 containing HDPE also has good tearability together with EVOH, and the PE first layer 20 based on LDPE can exhibit good sealing properties. Furthermore, by arranging adhesive layers 14, 16, and 18 composed of appropriate materials and thicknesses between the respective layers, it is possible to appropriately set the adhesive strength of each layer, which can contribute to good openability. It becomes.

(package)
The field in which the coextruded composite film for a lid of the distribution package of the present invention is used is mainly a lid for food containers and packaging. The film used for the bottom material is generally an unstretched coextruded film.
Ny layer / EVOH layer / seal layer. In general, this bottom material is formed to a depth of about 10 mm, and mayonnaise, ketchup, mustard, jam, etc. are placed therein and sealed to form a distribution container. Moreover, there exists a site | part currently shape | molded convexly toward the exterior of a package in the center part of a cover material, and the location corresponds to an opening. The lid member is heated and molded, and a convex portion is formed toward the outside of the container corresponding to the opening portion. The shape of the convex portion is intended to cause bending stress to concentrate on the opening portion when the container lid member is bent, the opening portion is torn, and the contents pop out. Examples of the shape of the other convex portion include a quadrangular pyramid shape, a semicircular shape (dome shape), and a cube. However, as long as the stress can be concentrated, the shape of the convex portion is not limited thereto. For molding, male-female molding is suitable for the purpose of sharpening the convex shape.

Furthermore, in order to concentrate bending stress, the following forms are effective.
(1) The cut is continuously put in the center of the formed convex shape at a depth of about 10 to 50% with respect to the total thickness of the lid with a cutting blade in the same direction as the direction in which the lid is folded.
(2) A cut line is formed in a dotted line shape at about 2 to 10 mm only at the apex portion of the molding convex portion. and so on.

On the other hand, it is preferable to use an unstretched coextruded composite film for the bottom material. As composition
The Ny layer / EVOH layer / PE layer is effective in terms of oxygen barrier properties, deep drawing suitability, and the tolerability of the lower heating hot plate (contact heating) of the preheater. In order to fill the viscous body as the contents, deep drawing is performed. As a process, after film heating (contact heating to a hot plate), a method of compressed air / vacuum forming is generally used. The heating temperature is preferably 85 to 110 ° C. The molded bottom material is filled with a viscous body, combined with the molded lid material, and heat-sealed. This seal is completely sealed without being peeled off at the seal surface interface of the lid bottom material. The package size is about 20 to 100 mm in length, 20 to 100 mm in width, and about 3 to 40 mm in depth. In the unsealing method, holding the both ends of the package with one hand and crushing the package in such a direction that the bottom material comes inward from the center of the lid material, the convex portion of the lid material is torn and the contents are discharged.

Examples of the present invention will be described below, but the present invention is not limited thereto.
<Film formation>
The films of Examples 1 and 2 and Comparative Examples 1 and 2 were formed by the coextrusion method or a combination of the coextrusion method and the dry laminating method, and evaluated.

Example 1
A film having the following layer constitution was obtained by co-extrusion of all layers, and Example 1 was obtained. Printing was performed on the copolymerized polyester-based resin layer as the surface layer.
(Print) Copolyester resin / adhesive layer / HIPS (80% by mass) + GPPS (20% by mass) / adhesive layer / EVOH / adhesive layer / LDPE / LDPE

(Example 2)
A film of Example 2 below was obtained, which was different from Example 1 in the blending ratio of the PS layer and the PE second layer.
(Printing) Copolymerized polyester resin / adhesive layer / HIPS (50% by mass) + GPPS (50% by mass) / adhesive layer / EVOH / adhesive layer / LDPE (50% by mass) + HDPE (50% by mass) / LDPE

(Comparative Example 1)
A film according to Comparative Example 1 was obtained by dry-laminating a coextruded composite sheet having the following layer structure on a printed PVC sheet.
(Print) PVC // EVOH / Ny / Adhesive layer / LDPE / LDPE

(Comparative Example 2)
Printing was performed on one side of the 16 μm-thick molded PET, and the other side was dry-laminated on a PS sheet prepared separately. Further, a coextruded composite film having the following layer structure was dry laminated on the other side of the PS sheet to obtain a film according to Comparative Example 2.
Molded PET (printing) // PS sheet // EVOH / Ny / adhesive layer / LDPE

  Table 1 summarizes the layer configurations of the films according to the above Examples and Comparative Examples, and the thicknesses of the respective layers.

  Table 2 summarizes the manufacturers and product names of the materials used in the respective layers of the above Examples and Comparative Examples.

  <Package manufacturing conditions>

A coextruded composite film having the following layer structure as a bottom material was molded under the following molding conditions. The layer thickness of each layer was Ny: 50 μm, EVOH: 10 μm, and LLDPE: 90 μm.
(Layer structure)
Bottom material: Ny / EVOH / LLDPE (seal layer)
(Molding condition)
Bottom material molding heating temperature: 150 ° C, Bottom material molding heating time: 3 seconds Lid material molding heating temperature: 160 ° C, Lid material molding heating time: 2 seconds Lid / bottom material sealing temperature: 160 ° C, Lid / bottom material sealing time : 2 seconds Contents: Water 15cc / pack

<Performance evaluation test method and evaluation criteria>
Five types of performance evaluation tests described below were conducted, and the coextruded composite film for the lid of the distribution package was evaluated based on predetermined evaluation criteria.

(1) Interlayer adhesion strength with plastic sheet:
The maximum load when a 15 mm wide film was peeled off at a tensile rate of 200 mm / min with a tensile tester at room temperature was measured.
6-15N / 15mm width: Excellent 3.9-6N / 15mm width: Good 3.9N / 15mm width or less: Defect

(2) Coextrusion film film breakability:
The package was opened, and how to cut the coextruded composite film portion was visually observed.
No film residue or stringing at the opening. : 5
There is almost no film residue and stringing at the opening. : 4
Slight film residue and stringing are observed at the opening. : 3
Remaining film at opening and stringing are observed. : 2
There is noticeable film residue and stringing at the opening. : 1

(3) Crackability of plastic sheet:
The package was opened, and the straight cracking property of the main constituent layer was evaluated.
It breaks linearly and smoothly without sticking. : 5
It breaks smoothly in a straight line. : 4
The sticky and hard to break breaks linearly. : 3
Does not break linearly. : 2
Even if it is sticky and hard to crack, it is not linear. : 1

(4) Openability (content discharge mode):
A total of 50 packages were opened, and the direction in which the contents were discharged was observed.
Dispense completely according to the aim. : 5
More than 90% is discharged as aimed. : 4
More than 50% is discharged according to the aim. : 3
Less than half of the items are discharged in the aiming direction. : 2
All discharge in a different direction from the target. : 1

(5) Scratch property of the printed layer:
The printed layer surface side (lid side) of the packed product was placed in contact with the dried noodles, and the scumming state of the printed layer was observed when it was shaken 50 times horizontally in the horizontal direction with a width of 100 mm.
No shading at all. : 5
There is a slight shading. : 4
There is a blur but it is not noticeable. : 3
There is a spot. : 2
There is a noticeable blur. : 1

<Evaluation results>
The evaluation test results are shown in Table 3.

  Example 1 uses a blend of HIPS (80% by mass) and GPPS (20% by mass) as a material constituting the PS layer as the main constituent layer, and constitutes the second PE layer of the seal layer. A single LDPE was used as the material. On the other hand, in Example 2, as a material for forming the PS layer, a blended material of HIPS (50% by mass) and GPPS (50% by mass) is used, and a material for forming the PE second layer of the sealing layer. A blended product of LDPE (50% by mass) and HDPE (50% by mass) was used. That is, in Example 2, compared with Example 1, the ratio of impact-resistant PS (HIPS) in the PS layer is reduced, and the ratio of high-density PE (HDPE) in the PE second layer in the seal layer is increased. As a result, slight differences were observed in “interlaminar film breakability” and “crackability”. However, these are within the range defined by the present invention and can be used without any problem in practice.

  On the other hand, Comparative Example 1 uses a conventional type chlorine-containing resin (PVC), but it was greatly inferior in terms of interlayer film breakability, unsealing property, and print layer blur evaluation. Although the PVC layer and the coextruded composite film are joined by dry lamination, the reason is that Ny is used for the intermediate layer and no copolyester resin is used for the printing surface. It seems to have been.

  In Comparative Example 2, a conventional non-chlorine resin (PET) is used. It has two dry laminate layers and is inferior in productivity. Moreover, the result which is greatly inferior also in the point of an interlayer film cutting | disconnection property and an openability was shown.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, the invention can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and a coextruded composite film for a lid of a distribution package accompanying such a change is also a technique of the present invention. Should be understood as being included in the scope.

It is sectional drawing which shows the layer structure of the coextruded composite film for lid | cover materials of the distribution package of this invention. It is a perspective view which shows the external appearance of a distribution package.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bottom material 2 Cover material 3 Convex part 4 Half cut 10 Surface layer 11 Intermediate layer 12 Seal layer 13 Copolyester resin layer 14 Adhesive third layer 15 PS layer 16 Adhesive second layer 17 EVOH layer 18 Adhesive first layer 19 PE Second layer 20 PE first layer 100 Coextruded composite film for lid of distribution package 200 Distribution package

Claims (13)

A coextruded composite film for a lid of a distribution package in which a surface layer, an intermediate layer, and a seal layer are laminated in this order,
The surface layer is composed of at least one copolyester resin layer,
The intermediate layer is composed of a polystyrene resin (PS) layer, at least one adhesive layer and an ethylene-vinyl acetate copolymer saponified resin (EVOH) layer having an ethylene content of 29 to 47 mol%,
The seal layer includes a PE first layer and a PE second layer from the seal layer side, and the PE second layer is a layer containing LDPE and HDPE,
The PS layer is a main constituent layer , and the resin constituting the PS layer is a mixture of general-purpose polystyrene (GPPS) and impact-resistant polystyrene (HIPS) . The composite film according to claim 1, wherein the intermediate layer is laminated in the order of a PS layer, an adhesive layer, and an EVOH layer from the surface layer side. The thickness ratio of the EVOH layer, the PE layer, the PS layer, and the copolyester resin layer is 1 to 7.5: 1.5 to 70:25 to 350: 2.5 to 35. The composite film as described. Each said layer is laminated | stacked in order of the PE layer, the adhesion | attachment 1st layer, the EVOH layer, the adhesion | attachment 2nd layer, PS layer, the adhesion | attachment 3rd layer, and the copolyester-type resin layer from the seal layer side. The composite film in any one. The thickness ratio of the EVOH layer, the first adhesive layer, the second adhesive layer, and the third adhesive layer is 1 to 7.5: 2.5 to 15: 2.5 to 15: 2.5 to 25. 4. The composite film according to 4. The composite film according to claim 1, wherein the total thickness of each layer is 75 to 1035 μm. The composite film according to any one of claims 1 to 6, wherein each of the first PE layer and the second PE layer has a thickness of 2 to 70 µm. The composite film according to claim 1, wherein the first PE layer is a layer made of low-density polyethylene (LDPE). The composite film according to any one of claims 1 to 8, wherein a mixing ratio of LDPE and HDPE in the second PE layer is 40 to 80:60 to 20 in terms of mass ratio. The composite film according to any one of claims 1 to 9, wherein an adhesive strength between the PS layer and the EVOH layer is 3.9 to 15 N / 15 mm. The composite film according to any one of claims 1 to 10, wherein the resin constituting the adhesive layer is a polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof. A lid for a distribution package formed by the coextruded composite film for a lid of a distribution package according to any one of claims 1 to 11 . A distribution package using the lid material according to claim 12 .

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