JP2009297935A - Moistureproof packaging material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moistureproof packaging material which is improved in moistureproof properties of a seal part end surface, and can effectively suppress the deterioration of contents caused by water in a package. <P>SOLUTION: The moistureproof packaging material is made of the laminate of at least a base film 1, aluminum foil 4, and a sealant film 6. A three-layer coextruded moistureproof film in which linear low density polyethylene, high density polyethylene, and linear low density polyethylene are laminated in turn is used as the sealant film 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a packaging material for contents that are very hateful of moisture, such as a sensor chip for measuring blood sugar level and lactic acid level. In particular, the moisture resistance of the end face of the seal part is higher than that of the conventional one, and it depends on the moisture content. The present invention relates to a moisture-proof packaging material with little deterioration.

  In the packaging of articles such as contents sensitive to the influence of moisture, such as sensor chips for in vivo information measurement for measuring blood sugar levels and lactic acid levels in body fluids (for example, see Patent Document 1). A laminate based on a three-layer structure in which an aluminum foil for imparting moisture resistance is laminated on a substrate film for printing and a sealant layer for heat sealing is further provided is often used.

  For example, as a base film, a film having moisture resistance by using a polyolefin resin having moisture resistance or providing a polyvinylidene chloride coating layer on these polyolefin, polyester or polyamide films is most common. is there.

  The packaging body using these moisture barrier base materials has spread to various uses because of its high moisture barrier property. However, since these moisture barrier base materials use chlorinated polymers, alternatives are being studied. In addition, some contents may be deteriorated due to slight humidity and moisture, and the moisture barrier property from the outside of the packaging container also wants to remove moisture that enters through the sealant inside the sealant. Needs are emerging.

  In order to eliminate the influence of residual moisture on the inside of the package, a method of enclosing the desiccant contained in the sachet together with the contents has been used in the past. It was not desirable because it was costly and time-consuming to enclose the inside of the material and there was a risk of piercing the packaging material due to vibration of the desiccant sachet.

  Under such circumstances, several proposals have been made for the purpose of eliminating the influence of residual moisture and preventing entry of moisture from the outside by devising the configuration of the packaging material itself.

  In Patent Document 2, there is a layer of a hygroscopic material in a laminate of a packaging container, and in particular, the hygroscopic material is a cellulose such as polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, cellophane, polyvinyl acetal, polyethylene glycol, or the like. A laminate having a configuration in which moisture inside the container is reduced by being one of polyhydric alcohols has been proposed.

  In Patent Document 3, by providing a polyolefin resin composition layer formed by blending an inorganic compound having a moisture absorption function inside a polyolefin resin layer made of a crystalline polyolefin resin having moisture resistance, the influence of residual moisture is reduced. A configuration has been proposed in which it is possible to eliminate the moisture and to prevent moisture from entering from the outside. In this case, it is necessary that the inorganic compound has a hygroscopic capacity of at least 10% of its own weight under 40 ° C.-90% relative humidity, and a sulfate compound such as zeolite, calcium oxide, calcium chloride, magnesium sulfate, alumina, It is selected from at least one of activated carbon, clay mineral, and silica gel.

In Patent Document 4, in a moisture-absorbing film comprising a multilayer film including a polyolefin-based resin composition layer containing an inorganic compound having a moisture-absorbing function, a laminate in which a polyolefin-based resin layer is provided on one side or both sides of the polyolefin-based resin composition layer In the body, from the viewpoint of the balance between the rigidity and flexibility of the film, it has been proposed to have a configuration in which the upper limit of the density of the polyolefin-based resin composition layer containing an inorganic compound and the lower limit of the density of other layers are defined.

  In Patent Document 5, blended resin containing ethylene-α, β-unsaturated carboxylic acid or an ionic cross-linked product thereof is blended with polyolefin resin, and further, with respect to its own weight in 90% relative humidity atmosphere with respect to 100 parts by weight of resin A moisture-proof film having a composition in which 1 to 100 parts by weight of an inorganic compound having a hygroscopic property of at least 10% or more is mixed has been proposed. In this case, the inorganic compound is selected from at least one of zeolite, calcium oxide, calcium chloride, sulfate compounds such as magnesium sulfate, alumina, activated carbon, clay mineral, and silica gel.

  However, it is difficult to apply the methods proposed in Patent Documents 2 to 5 as they are as a method for removing moisture that enters through the sealant from the seal portion of the package.

  In the method of Patent Document 2, the material of the hygroscopic material is not suitable for the sealant. In the method of Patent Document 3, the sealing property of the polyolefin resin composition layer formed by blending an inorganic compound having a moisture absorbing function is lowered. In Patent Document 4, the specification of the upper limit of the density of the polyolefin resin composition layer and the lower limit of the density of other layers for balancing the rigidity and flexibility of the film may be contrary to the direction of suitability as a sealant. In Patent Document 5, in which it is difficult to determine a compromise, it is predicted that the sealing performance is similarly lowered even in a composition in which a blend resin and an inorganic compound are mixed.

  From the above situation, in the case of contents that do not like moisture intrusion from the end face of the seal portion of the packaging material, a high-density polyethylene (HDPE) film having high moisture resistance is currently used as the sealant film.

  HDPE has high moisture resistance, but its sealing property is poor compared to linear low density polyethylene (LLDPE) and the like. In addition, when laminating as a packaging material or filling the contents, HDPE rubs against some roll, etc., causing white powdery residue or bleeding out of low molecular weight substances, causing poor appearance and poor sealing. There are many things.

  Conventionally, HDPE has been produced by a low pressure method using a Ziegler type catalyst, and is usually produced by a slurry polymerization method using an organic solvent which is inert to polymerization. Among these HDPEs, when producing HDPE having an arbitrary molecular weight distribution for the purpose of controlling moldability and physical properties, the polymerization is performed in multiple stages, and the molecular weight and density of the polymer usually produced in each stage are controlled. Polymerization.

  Among the resins marketed as HDPE, for example, HDPE with a narrow molecular weight distribution produced by single-stage polymerization has a narrow processing range, and conversely, HDPE produced by multi-stage polymerization to improve processability has a molecular weight distribution. However, there is a problem that the content of low molecular weight substances is high.

As a result, considering that the moisture resistance of the end face of the seal portion is reduced, and the storage performance is insufficient for contents that are very hated of moisture, such as a sensor chip for measuring blood sugar level and lactic acid level, There is a need for a packaging material that has a moisture resistance higher than that of the conventional one at the end face of the seal portion.
JP 2004-147845 A Japanese Patent Laid-Open No. 2005-3413 JP 2004-352255 A JP 2004-351697 A JP 2004-143111 A

  To provide a moisture-proof packaging material in which the moisture resistance of the end face of the seal part is higher than that of the conventional one and the content is less deteriorated by moisture.

  The invention of claim 1 of the present invention is a packaging material comprising a laminate of at least a base film, an aluminum foil, and a sealant film, wherein the moisture-proof packaging material uses a moisture-proof film for the sealant film. .

  The invention of claim 2 of the present invention is characterized in that the moisture-proof film is a three-layer coextrusion film laminated in the order of linear low density polyethylene / high density polyethylene / linear low density polyethylene. The moisture-proof packaging material described in 1.

  In the invention of claim 3 of the present invention, the film thickness ratio of three layers laminated in the order of linear low density polyethylene / high density polyethylene / linear low density polyethylene is 1/8/1 to 3/4/3. It is a range, It is a moisture-proof packaging material of Claim 2.

  The invention of claim 4 of the present invention is the moisture-proof packaging material according to any one of claims 1 to 3, wherein the laminate includes an intermediate layer film.

  As the packaging material of the present invention, it is possible to effectively prevent moisture from being transmitted from the outside in the film thickness direction of the packaging material by using a laminate including an aluminum foil having a high barrier property, and to be moisture-proof to the sealant film. Providing a moisture-proof packaging material that can prevent moisture permeation through the inside of the coating of the seal part by using a film, has a higher moisture-proof property on the end face of the seal part than conventional ones, and has less deterioration due to moisture in the contents I can do it.

  Compared to HDPE alone by using a film laminated in the order of linear low density polyethylene (LLDPE) / high density polyethylene (HDPE) / linear low density polyethylene (LLDPE) for the moisture-proof film used in the packaging material of the present invention. By using LLDPE on both the laminating surface side and the sealing surface side, the sealing performance is better than that of HDPE alone and seal defects are reduced. In addition, it is possible to suppress seal unevenness due to low molecular weight substances generated from HDPE during processing and seal defects due to mixing of HDPE rubbing residue.

  By coextruding the moisture-proof film used in the packaging material of the present invention to form a multilayer film, it is possible to achieve effects within the same range of productivity and cost without increasing the number of special steps.

  By setting the film thickness ratio of LLDPE / HDPE / LLDPE in the order of LLDPE / HDPE / LLDPE as the moisture-proof film used in the packaging material of the present invention to a range of 1/8/1 to 3/4/3, The defect in the case of a single HDPE can be prevented without lowering the moisture resistance.

  By including an intermediate layer film in the laminate used for the packaging material of the present invention, it is possible to prevent piercing pinholes due to the contents (sensor chip, desiccant, etc.).

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory cross-sectional view of an example of the moisture-proof packaging material of the present invention. FIG. 2 is a cross-sectional explanatory view of an example of the moisture-proof packaging material of the present invention. FIG. 3 is a cross-sectional explanatory view of an example of a moisture-proof sealant used in the moisture-proof packaging material of the present invention. FIG. 4 is a schematic view of a four-side sealed bag package using the moisture-proof packaging material of the present invention.

  The moisture-proof packaging material of the present invention is a packaging material comprising at least a laminate of a base film, an aluminum foil, and a sealant film, wherein the moisture-proof film is used as the sealant film.

  An example of the layer structure of the laminate is shown in FIG. 1, and another example of the layer structure corresponding to claim 4 is shown in FIG.

  The substrate film 1 is a transparent film that functions as a shape-retaining property and a printing substrate. For example, a polyester film such as polyethylene terephthalate or polyethylene naphthalate, a polyolefin film such as polyethylene or polypropylene, a polystyrene film, a polyamide film, a poly A biodegradable plastic film such as a vinyl chloride film, a polycarbonate film, a polyacrylonitrile film, a polyimide film or a polylactic acid film is used, and those having mechanical strength and dimensional stability are preferable. In particular, a polyethylene terephthalate film stretched biaxially from the viewpoint of heat resistance or the like is preferably used.

  Various known additives and stabilizers such as an antistatic agent, an ultraviolet ray preventing agent, a plasticizer, and a lubricant may be used on the surface of the base film 1 to improve the adhesion to the thin film. Therefore, corona treatment, low temperature plasma treatment, ion bombardment treatment may be performed as pretreatment, and chemical treatment, solvent treatment, etc. may be performed.

  The thickness of the base film 1 is 1 μm or more, and considering the suitability and processability as a packaging material, it can be practically selected in the range of 3 to 200 μm, but in many applications it should be 6 to 30 μm. preferable.

  Examples of the dicarboxylic acid component constituting the polyester when the base film 1 is a polyester film include terephthalic acid, naphthalenecarboxylic acid, isophthalic acid, diphenyldicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid, and 5-sodium. Aromatic dicarboxylic acids such as sulfoisophthalic acid and phthalic acid, alicyclic dicarboxylic acids such as cyclohexyne dicarboxylic acid, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, and fumaric acid Examples thereof include oxycarboxylic acids such as acids and p-oxybenzoic acid.

  Examples of the dialcohol component constituting the polyester include aliphatic glycols such as ethylene glycol, propanediol, 1,4 butanediol, 1,6 hexanediol, and neopentyl glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, Examples thereof include polyoxyalkylene glycols such as 1,4 cyclohexanedimethanol, aromatic glycols such as bisphenol A and bisphenol S, and derivatives thereof.

Among these polyesters, those mainly composed of polyethylene terephthalate and polyethylene naphthalate are preferable from the viewpoints of film forming properties such as biaxial stretching properties, humidity properties, heat resistance, and chemical resistance, and particularly polyethylene terephthalate is used. Is common.

  As the ink layer 2 printed on the base film 1 as necessary, a commonly used ink can be used, and a known method such as a gravure printing method or an offset printing method can be applied as a printing method.

  The aluminum foil 4 used in the laminate of the moisture-proof packaging material of the present invention guarantees a barrier property for protecting the contents, and its thickness is more than a certain value to prevent the occurrence of pinholes and the like. It is necessary. Further, from the viewpoint of workability at the time of laminating and the cost, the thickness is desirably below a certain level. Considering the stability of the foil production, the thickness of the aluminum foil is preferably in the range of 5 μm to 50 μm, and more preferably in the range of 15 to 30 μm.

  The lamination method of the aluminum foil and the plastic film can be performed by a known method such as a dry lamination method.

  The dry lamination method is a method in which an adhesive is applied on one base material layer and bonded to the other base material. The coating section, the drying device, and the nip roller section are unrolled, wound and It consists of a tension control system.

  For the coating part, the gravure roll coating method is common because it is necessary to ensure the stability of the coating amount. When high coating amount and smoothness of the coated surface are required, the gravure reverse roll coating method is adopted. Yes.

  As the adhesive used in the dry lamination method, generally, polyurethane, polyacrylic, polyester, epoxy, polyvinyl acetate, cellulose, and other laminating adhesives can be used.

  Lamination adhesives are solvent-based adhesives or solvent-free adhesives, but when solvent-free adhesives are used, a drying device is not required, especially the non-solvent dry lamination method. It is out.

  The adhesive used for the adhesive layers 3 and 5 is that the adhesive strength between the base material 1 and the aluminum foil 4 which is a plastic film does not deteriorate due to long-term use and does not cause delamination, and the adhesive is yellow. It is necessary not to change, and urethane adhesives can be used. For example, a two-component curable polyurethane resin adhesive having a polyol component and an isocyanate component is used. The polyurethane resin-based adhesive is easy to react with active hydrogen contained in many functional groups, and has good solubility and wettability with the adherend. Therefore, it is high in various plastic film or sheet combinations. Shows adhesion.

  The moisture-proof sealant 6 used for the laminate of the moisture-proof packaging material of the present invention is for ensuring waterproof and moisture-proof properties against moisture entering from the seal end, and is manufactured by a usual three-layer coextrusion method. It consists of LLDPE / HDPE / LLDPE.

If the thickness of the moisture-proof sealant 6 is large, the moisture-proof property from the end face is lowered, and if it is thin, the film formation is not stable, so it is necessary to be within a certain range, and the range of 15 to 30 μm is required. desirable.
A cross section of an example of the layer structure of the moisture-proof sealant 6 is shown in FIG.

Conventionally, HDPE has been used as a film having low moisture permeability among polyolefin films having heat sealability, but in the moisture-proof packaging material of the present invention, the instability of the laminate by using HDPE alone as a sealant, That is, the sealing conditions are higher than those of LDPE and LLDPE, there are many low molecular weight component bleeds, and there is a lot of residue generated due to contact with the rolls during transportation. Succeeded in preventing defects.

  The HDPE 13 constituting the intermediate layer of the sealant 6 preferably has a density of 0.940 or more from the viewpoint of moisture resistance. As for the film thickness ratio of each layer of the sealant 6, when the ratio of LLDPE is high, the moisture resistance from the end face is lowered, and when the ratio of LLDPE is low, the instability of the seal itself is caused. It is desirable that the ratio of LLDPE / HDPE / LLDPE is in the range of 1/8/1 to 3/4/3.

  FIG. 2 shows a cross section of a sealant 6 provided with an intermediate layer 7 for preventing piercing pinholes by contents such as sensor chips and desiccant sachets.

Various films can be used for the intermediate layer 7 in the same manner as the base film 1, but in many cases, a stretched PET film is preferably used because of its heat resistance and dimensional stability. Are stacked.
An overview of an example of a package using the moisture-proof packaging material of the present invention is shown in FIG.

  Specific examples of the present invention will be described below.

<Example 1>
Moisture-proof packaging material for blood glucose level sensor chip by laminating stretched PET film with thickness of 12 μm, aluminum foil with thickness of 15 μm, stretched PET film with thickness of 12 μm, and moisture-proof sealant with thickness of 30 μm in order by dry laminating method Got.

  The moisture-proof sealant having a thickness of 30 μm was a three-layer coextruded film of LLDPE 6 μm / HDPE 18 μm / LLDPE 6 μm, and HDPE having a density of 0.960 was used.

  Thereafter, the sensor chip was packaged and filled with the moisture-proof packaging material in a four-side seal filling machine to prepare a package for evaluation.

<Comparative Example 1>
A moisture-proof packaging material for a blood glucose sensor chip by laminating a 15 μm thick aluminum foil, a 12 μm thick stretched PET film, and a 30 μm thick HDPE sealant film sequentially on a stretched PET film having a thickness of 12 μm by a dry laminating method. Got.

  HDPE having a density of 0.960 was used.

  Thereafter, the sensor chip was packaged and filled with the moisture-proof packaging material in a four-side seal filling machine to prepare a package for evaluation.

<Comparison result>
<Evaluation items>
(1) Moisture proof: after sealing in 4 directions, stored for 6 months at 40 ° C. and 75% RH and judged by sensor chip performance deterioration → ○… No performance deterioration ×… There is performance deterioration (2) Workability: 4 Judging by the appearance defect and laminating defect due to the occurrence of waste when sealed, → ○… No appearance, no lamination failure ×… There is an appearance, poor lamination <Evaluation Result>
Example: Moisture resistance ○ Processing suitability ○
Comparative example: Moisture resistance ○ Processing suitability ×
From the above results, the moisture-proof packaging material using the moisture-proof sealant of the example of the present invention was superior in the long-term moisture resistance and processability of the package to the packaging material of the comparative example using the sealant of HDPE alone.

  Therefore, according to the moisture-proof packaging material of the present invention, moisture permeation from the outside can be effectively prevented, and moisture permeation through the inside of the seal portion can be prevented by using a moisture-proof film for the sealant film. As a result, it was possible to provide a moisture-proof packaging material in which the moisture resistance of the end face of the seal portion is higher than that of the conventional one and the content is less deteriorated by moisture.

Cross-sectional explanatory drawing of an example of the moisture-proof packaging material of this invention. Cross-sectional explanatory drawing of an example of the moisture-proof packaging material of this invention. Cross-sectional explanatory drawing of an example of the moisture-proof sealant used for the moisture-proof packaging material of this invention. Overview of a four-side sealed bag package using the moisture-proof packaging material of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base film 2 ... Ink layer 3 ... Adhesive layer 4 ... Aluminum foil 5 ... Adhesive layer 6 ... Moisture-proof sealant 7 ... Intermediate film 8 ... Adhesive layer 9 ... Packaging material 10 ... Seal part 11 ... Notch 12 ... Contents 13 ... HDPE
14 ... LLDPE
15 ... LLDPE
A ... HDPE film thickness B ... LLDPE film thickness C ... LLDPE film thickness

Claims (4)

  A moisture-proof packaging material comprising a laminate of at least a base film, an aluminum foil and a sealant film, wherein a moisture-proof film is used as the sealant film.   The moisture-proof packaging material according to claim 1, wherein the moisture-proof film is a three-layer coextrusion film laminated in the order of linear low density polyethylene / high density polyethylene / linear low density polyethylene.   The film thickness ratio of three layers laminated in the order of linear low density polyethylene / high density polyethylene / linear low density polyethylene is in the range of 1/8/1 to 3/4/3. 2. The moisture-proof packaging material according to 2.   The moisture-proof packaging material according to any one of claims 1 to 3, wherein the laminate includes an intermediate layer film.