JP7465688B2 - Transparent moisture absorbing laminate - Google Patents

Description

The present invention relates to a transparent moisture-absorbing laminate.

Traditionally, in the fields of food, medicine, electronic parts, precision machinery, recording materials, etc., a method of including a desiccant has been adopted to prevent quality deterioration caused by moisture. In addition, a desiccant is incorporated into the packaging material itself to give it moisture absorption capabilities, without the need to place a separate desiccant inside the package.

Patent Document 1 discloses an adsorbent composition containing a resin, a zeolite, and a given metal soap, as well as an adsorbent-containing film formed from the adsorbent composition.

Patent Document 2 discloses a polyester film for sealants that is composed of a polyester resin whose main component is ethylene terephthalate and that meets certain requirements. This film is said to be transparent and have low adsorption properties.

Patent Document 3 also describes a film that has extremely high transparency and is useful as a sealing film for organic electroluminescence (EL) displays.

The method for producing nano-sized zeolite is described in Patent Documents 4 and 5.

Patent No. 2885079 JP 2017-210541 A JP 2018-100390 A JP 2011-246292 A JP 2013-49602 A

The film described in Patent Document 1 is white before absorbing moisture, and therefore, when this film is used as a packaging material such as a bag, there is a problem in that the contents cannot be seen.

Therefore, there is a need to provide a transparent moisture-absorbing laminate that combines moisture absorption, transparency, and functionality.

As a result of intensive research, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is as follows:
<Aspect 1> A film having a transparent barrier substrate layer, a transparent moisture-absorbing layer, and a transparent functional layer in this order, or a transparent barrier substrate layer, a transparent functional layer, and a transparent moisture-absorbing layer in this order, and the transparent moisture-absorbing layer contains a thermoplastic resin and a moisture absorbent.
Transparent moisture absorbing laminate.
<Aspect 2> The transparent moisture-absorbing laminate according to aspect 1, wherein the thermoplastic resin of the transparent moisture-absorbing layer is a polyolefin-based resin.
<Aspect 3> The transparent moisture-absorbing laminate according to aspect 1 or 2, wherein the moisture absorbent is a zeolite.
<Aspect 4> The transparent moisture-absorbing laminate according to aspect 3, wherein the average particle diameter D50 of the zeolite in the transparent moisture-absorbing layer is 300 nm or less.
<Embodiment 5> The transparent moisture-absorbing laminate according to any one of embodiments 1 to 4, wherein the transparent moisture-absorbing layer further contains an ester compound having an HLB value of 5 or less.
Aspect 6: The transparent moisture-absorbing laminate according to any one of aspects 1 to 5, further comprising a transparent skin layer laminated on one or both sides of the transparent moisture-absorbing layer.
<Embodiment 7> The transparent moisture-absorbing laminate according to any one of embodiments 1 to 6, wherein the transparent functional layer is a transparent gas-absorbing layer.
<Embodiment 8> The transparent moisture-absorbing laminate according to any one of embodiments 1 to 6, wherein the transparent functional layer is a transparent non-adsorptive layer.
<Embodiment 9> The transparent moisture-absorbing laminate according to any one of embodiments 1 to 6, wherein the transparent functional layer is a transparent, easily peelable layer.
A tenth aspect of the present invention is a packaging device comprising one or more transparent moisture-absorbing laminates according to any one of the first to ninth aspects, and a part of the one or more transparent moisture-absorbing laminates opposite to the transparent barrier substrate layer side is heat-sealed to another part of the transparent moisture-absorbing laminate or to another film to form a bag shape.
Packaging bag.
Aspect 11: The packaging bag according to aspect 10. A content-containing packaging bag having a content stored in the packaging bag.

The present invention provides a transparent, moisture-absorbing laminate that combines moisture absorption, transparency, and functionality.

FIG. 1 is a schematic cross-sectional view of the transparent moisture-absorbing laminate of the present invention.

<<Transparent moisture-absorbing laminate>>
As shown in FIG. 1, the transparent moisture-absorbing laminate 100 of the present invention is
The film has a transparent barrier substrate layer 12, a transparent moisture-absorbing layer 14, and a transparent functional layer 18 in this order (FIG. 1(a)), or has a transparent barrier substrate layer 12, a transparent functional layer 18, and a transparent moisture-absorbing layer 14 in this order (FIG. 1(b)), and the transparent moisture-absorbing layer 14 contains a thermoplastic resin and a moisture absorbent.

In the present invention, "transparent" means that the material is sufficiently transparent to allow the contents to be visually recognized, and for example means that the total light transmittance is 50% or more, 60% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 100%, and the haze value is 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, or 10% or less.

The above configuration makes it possible to provide a transparent hygroscopic laminate that combines hygroscopicity, transparency, and functionality.

The transparent moisture-absorbing laminate 100 may further include a transparent skin layer 16 laminated on one or both sides of the transparent moisture-absorbing layer 14. Although not shown, the transparent skin layer may be laminated on one or both sides of the transparent functional layer, or the transparent functional layer may be present in a position corresponding to the transparent skin layer.

The transparent functional layer may be laminated over the entire transparent moisture absorbing layer.

Each component of the present invention is described below.

<Transparent Barrier Substrate Layer>
The transparent barrier substrate layer is a substrate having transparency and barrier properties.

As the transparent barrier substrate layer, for example, a barrier resin layer can be used. As the resin constituting the barrier resin layer, for example, a cyclic olefin polymer, an ethylene-vinyl alcohol copolymer, polychlorotrifluoroethylene, etc. can be used.

The transparent barrier substrate layer may also be a layer having a transparent barrier layer and a transparent substrate resin layer. In this case, an adhesive layer may be present between the transparent barrier layer and the transparent substrate resin layer.

(Transparent Barrier Layer)
The transparent barrier layer may be made of a material that is transparent and can suppress the permeation of moisture, organic gases, and inorganic gases from the outside into the transparent moisture absorbing layer. Such a transparent barrier layer may be, for example, an inorganic vapor deposition film such as a silica vapor deposition film, an alumina vapor deposition film, or a silica-alumina binary vapor deposition film, or an organic coating film such as a polyvinylidene chloride coating film, a polychlorotrifluoroethylene coating film, or a polyvinylidene fluoride coating film. The above-mentioned barrier resin layer may also be used as the transparent barrier layer.

When an inorganic vapor deposition film is used as the transparent barrier layer, the thickness of the transparent barrier layer is preferably 100 nm or more, 200 nm or more, 300 nm or more, 500 nm or more, 700 nm or more, or 1 μm or more from the viewpoint of ensuring strength and barrier properties, and is preferably 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less from the viewpoint of improving handleability as a package.

When a barrier resin layer or an organic coating film is used as the transparent barrier layer, the thickness of the transparent barrier layer is preferably 7 μm or more, 10 μm or more, or 15 μm or more from the viewpoint of ensuring strength and barrier properties, and is preferably 100 μm or less, 80 μm or less, 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, or 35 μm or less from the viewpoint of improving handleability as a package.

(Transparent Substrate Resin Layer)
As the transparent substrate resin layer, a thermoplastic resin having excellent impact resistance, abrasion resistance, etc., such as a polyolefin resin, a vinyl polymer, a polyester, a polyamide, etc., can be used alone or in a multi-layer structure by combining two or more kinds. This resin layer may be a stretched film or a non-stretched film. In addition, this resin layer may be present on one or both sides of the transparent barrier layer. This resin layer can protect the transparent barrier layer.

Examples of polyolefin resins include polyethylene resins and polypropylene resins.

In this specification, a polyethylene resin is a resin that contains more than 50 mol%, 60 mol% or more, 70 mol% or more, or 80 mol% or more of repeating ethylene groups in the main chain of the polymer, and is selected from the group consisting of, for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-vinyl acetate copolymer (EVA), carboxylic acid modified polyethylene, carboxylic acid modified ethylene vinyl acetate copolymer, ionomer, and derivatives thereof, and mixtures thereof.

In this specification, a polypropylene-based resin is a resin that contains more than 50 mol%, 60 mol% or more, 70 mol% or more, or 80 mol% or more of repeating units of propylene groups in the main chain of the polymer, and examples thereof include polypropylene (PP) homopolymer, random polypropylene (random PP), block polypropylene (block PP), chlorinated polypropylene, acid-modified polypropylene, and derivatives thereof, as well as mixtures thereof.

Examples of vinyl polymers include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polychlorotrifluoroethylene, polytetrafluoroethylene, polyacrylonitrile (PAN), etc.

Examples of polyester include polyethylene terephthalate (PET) and polybutylene terephthalate.

Examples of polyamides include nylons such as Nylon (registered trademark) 6 and Nylon MXD6.

The thickness of the transparent substrate resin layer is preferably 7 μm or more, 10 μm or more, or 15 μm or more from the viewpoint of providing good protection for the transparent barrier layer, and is preferably 55 μm or less, 50 μm or less, or 45 μm or less from the viewpoint of improving the handleability of the package.

Transparent moisture absorbing layer
The transparent moisture absorbing layer is a layer that is transparent and has a moisture absorbing agent. In this case, the moisture absorbing agent may be dispersed in a thermoplastic resin. As the thermoplastic resin, the thermoplastic resins listed for the transparent substrate resin layer can be used, and among them, it is preferable to use a polyolefin resin, particularly a polyethylene resin, from the viewpoint of processability and the like.

The resin composition constituting the transparent moisture absorbing layer preferably has a melt flow rate of 0.3 g/10 min or more and 30 g/10 min or less when measured in accordance with JIS K7210 under conditions of a temperature of 190° C. and a load of 21.18 N, from the viewpoint of relatively easy molding into a film by the T-die method or the inflation method. This melt flow rate may be 0.5 g/10 min or more, 1.0 g/10 min or more, 3.0 g/10 min or more, or 5.0 g/10 min or more, and may be 20 g/10 min or less, 15 g/10 min or less, 10 g/10 min or less, 8.0 g/10 min or less, or 5.0 g/10 min or less. For example, this melt flow rate may be 0.5 g/10 min or more and 10 g/10 min or less.

The haze of the resin composition constituting the transparent moisture absorbing layer, when measured in a film having a thickness of 100 μm before moisture absorption in accordance with JIS K7136, is preferably 80% or less, and may be 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 15% or less, or may be 1% or more, 3% or more, or 5% or more. In this specification, the term "film before moisture absorption" refers to a film immediately after the resin composition is melted and formed into a film.

Examples of moisture absorbents that can be used include physical moisture absorbents such as hydrophilic zeolite and silica gel, and chemical moisture absorbents such as calcium oxide, magnesium sulfate, calcium chloride, calcium oxide, and aluminum oxide. Of these, it is preferable to use hydrophilic zeolite.

As hydrophilic zeolites, for example, A-type, X-type, or LSX-type zeolites can be used. These may be used alone or in combination.

When hydrophilic zeolite is used as the moisture absorbent, the average particle diameter D50 of the zeolite is preferably 300 nm or less from the viewpoint of imparting appropriate transparency to the composition. Here, the average particle diameter D50 of the zeolite means the particle diameter at 50% of the cumulative value in the particle size distribution based on the number of randomly selected 100 particles measured along their major axis using a scanning electron microscope (SEM). The average particle diameter D50 of the zeolite may be 250 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. The average particle diameter D50 of the zeolite may be 10 nm or more, 30 nm or more, 50 nm or more, or 100 nm or more. For example, the average particle diameter D50 of the zeolite may be 10 nm or more and 300 nm or less, or more than 100 nm and 250 nm or less.

When hydrophilic zeolite is used as the moisture absorbent, the pore (absorption opening) diameter of the zeolite may be 0.3 nm or more and 1 nm or less, or 0.3 nm or more and 0.5 nm or less.

When a hydrophilic zeolite is used as the moisture absorbent, the atomic ratio of Si to Al (Si/Al) in the zeolite is arbitrary, and may be, for example, 1 or more, 2 or more, 3 or more, 5 or more, 10 or more, or 15 or more, and may be, for example, 80 or less, 60 or less, 50 or less, 40 or less, or 30 or less.

The zeolite used in the present invention is preferably hydrophilic from the viewpoint of hygroscopicity, and it is particularly preferable to use Na-A type zeolite.

The zeolite used in the present invention can be produced, for example, by the methods described in Patent Documents 4 and 5. Such zeolites may be used after adjusting the bulk density as described in Patent Document 3.

From the viewpoint of ensuring good moisture absorption capacity, the content of the moisture absorbent is preferably 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, or 10% by mass or more based on the mass of the entire moisture absorption layer, and from the viewpoint of ensuring good transparency and film-forming properties, it is preferably 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less.

From the viewpoint of improving transparency, it is preferable that the transparent moisture absorbing layer further contains an ester compound with an HLB value of 5 or less. Here, the HLB value is an index showing whether the ester compound is hydrophilic or lipophilic. An HLB value of 5 or less of an ester compound means that the ester compound has high lipophilicity, and is a numerical value in the range in which the ester compound is used, for example, as a defoamer or an emulsifier for emulsions. This HLB value may be, for example, 4.5 or less, 4.0 or less, or 3.5 or less, or may be, for example, 2.0 or more, 2.5 or more, or 3.0 or more.

The ester compound is, for example, a monoester compound of a polyhydric alcohol and a fatty acid. The polyhydric alcohol may be, for example, glycerin, alkylene glycol, etc. The fatty acid may be, for example, a saturated or unsaturated fatty acid having 12 to 24 carbon atoms.

The ester compound may in particular be a monoester of an alkylene glycol having 2 to 6 carbon atoms and a fatty acid having 15 to 24 carbon atoms. The alkylene glycol may be, for example, ethylene glycol, propylene glycol, diethylene glycol, etc. The fatty acid having 15 to 24 carbon atoms may be saturated or unsaturated, for example, stearic acid, behenic acid, etc.

Specific examples of ester compounds include propylene glycol monostearate and propylene glycol monobehenate.

The content of the ester compound in the transparent moisture absorbing layer is not particularly limited as long as it is within a range that provides the advantageous effects of the present invention. For example, the content of the ester compound is 2.0% by mass or more and 15% by mass or less, and may be 2.5% by mass or more, 3.0% by mass or more, or 5.0% by mass or more, and may be 12% by mass or less, 10% by mass or less, 8.0% by mass or less, or 6.0% by mass or less. For example, the content of the ester compound may be 2.5% by mass or more and 12% by mass or less, or 3.0% by mass or more and 10% by mass or less.

The transparent moisture absorbing layer may or may not contain oxides (excluding zeolite) of one or more elements selected from Al, Si, Ti, and Zr, having an average particle size D50 of 100 nm or less. The content of such oxides may be, for example, 5 mass% or less, 3 mass% or less, 1 mass% or less, or 0 mass%.

The transparent moisture-absorbing layer can be produced by kneading the resin composition constituting the transparent moisture-absorbing layer using, for example, a batch-type kneader such as a kneader, Banbury mixer, or mixing roll conical mixer, or a continuous kneader such as a twin-screw kneader, and then molding the kneaded resin into a film by an extrusion molding method such as an inflation method or a T-die method. When a transparent skin layer is present on one or both sides of the transparent moisture-absorbing layer, the transparent skin layer and/or a transparent non-adhesive layer and/or a transparent easily peelable layer may be laminated together with the film formation by a co-extrusion method such as a multi-layer inflation method or a multi-layer T-die method.

<Transparent functional layer>
The transparent functional layer may be, for example, a transparent easily peelable layer, a transparent gas-absorbing layer, a transparent non-adsorptive layer, or the like.

<Transparent functional layer: transparent easily peelable layer>
As the transparent easy peelable layer, for example, a commercially available easy peel resin or easy peel sealant film may be used, or a coating capable of providing easy peelability may be used. As the coating capable of providing easy peelability, for example, a layer containing an acrylic modified polyolefin is preferably used from the viewpoint of transparency.

In the case of a coating, the thickness of the transparent peelable layer can be 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 0.7 μm or more, or 1.0 μm or more, and can be 20.0 μm or less, 10.0 μm or less, 8.0 μm or less, 5.0 μm or less, or 3.0 μm or less, and in the case of a film, the thickness can be, for example, 1 μm or more, 3 μm or more, 5 μm or more, 7 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more, and can be 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, or 50 μm or less.

<Transparent functional layer: transparent gas absorbing layer>
The transparent gas absorbing layer is a layer that is transparent and has a gas absorbent. In this case, the gas absorbent may be dispersed in a thermoplastic resin. As the thermoplastic resin, the thermoplastic resins listed for the transparent substrate resin layer can be used, and among them, it is preferable to use a polyolefin resin, particularly a polyethylene resin, from the viewpoint of processability and the like.

The transparency of the transparent gas absorbing layer can be obtained, for example, by adjusting the content of the gas absorbent.

The content of the gas absorbent may be 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 0.7% by mass or more, or 0.9% by mass or more, based on the total mass of the transparent gas absorbing layer. From the viewpoint of transparency, it is preferable that this content is 10% by mass or less, 8% by mass or less, 5% by mass or less, 3% by mass or less, or 1% by mass or less.

Examples of gas absorbents that can be used include physical gas absorbents such as activated carbon and hydrophobic zeolites, and chemical gas absorbents such as iron-based oxygen absorbents, metal halides, metal oxides, sulfates, sulfites, hydrogen sulfites, and dithionites.

As hydrophobic zeolites, for example, beta-type, ZSM-5-type, ferrienite-type, mordenite-type, L-type, or Y-type zeolites can be used. In addition, ZSM-11, silicalite, silicalite-2, and pentasil-type metallosilicates, which are analogues of ZSM-5-type zeolites, can also be used. These may be used alone or in combination.

As iron-based oxygen absorbers, iron powder (e.g., reduced iron powder, sprayed iron powder, activated iron powder, etc.), ferrous oxide, ferrous salts, etc. can be used.

Examples of metal halides that can be used include calcium chloride, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, calcium chloride, magnesium chloride, barium chloride, etc.

Examples of metal oxide that can be used include calcium oxide, aluminum oxide, cerium oxide with oxygen deficiencies, and titanium oxide with oxygen deficiencies.

<Transparent functional layer: transparent non-adhesive layer>
The transparent non-adsorptive layer is a layer that adsorbs little, and in particular does not substantially adsorb, volatile components such as l-menthol, d-limonene, methyl salicylate, camphor, tocopherol, and food aroma components such as wasabi, mustard, mustard, etc., and can maintain the aroma components, etc. inside the packaging container. The transparent non-adsorptive layer may be a single layer or a laminate.

In the present invention, "non-adsorbed" means that when one side of a non-adsorbing layer cut to a size of 10 cm x 10 cm is exposed to saturated l-menthol vapor in a 40°C environment for one week, the adsorbed l-menthol is extracted with methyl ethyl ketone, and the amount of l-menthol in the extract is quantified by gas chromatography, the amount of l-menthol adsorbed is 10 mg or less. This amount of adsorption can be 7 mg or less, 5 mg or less, 3 mg or less, 2 mg or less, 1 mg or less, 0.5 mg or less, 0.3 mg or less, or 0.1 mg or less, or it can be more than 0 mg.

The transparent non-adhesive layer may contain at least one selected from the group consisting of cyclic olefin resins, polyester resins, and ethylene-vinyl alcohol copolymers as a main component. In the present invention, "as a main component" means that the content in the transparent non-adhesive layer containing the above substance is 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total mass of the layer, and is 100% by mass or less, or less than 100% by mass.

The water vapor permeability of the transparent non-adsorptive layer as a whole in accordance with JIS K 7129 is preferably 0.5 g/( ^m2 ·day) or more in terms of ensuring a good moisture absorption rate from the inside. This water vapor permeability can be 1 g/( ^m2 ·day) or more, 2 g/( ^m2 ·day) or more, 3 g/( ^m2 ·day) or more, or 4 g/( ^m2 ·day) or more, and can be 100 g/( ^m2 ·day) or less, 90 g/( ^m2 ·day) or less, or 80 g/( ^m2 ·day) or less. It can be 70 g/( ^m2 ·day) or less, 60 g/( ^m2 ·day) or less, 50 g/( ^m2 ·day) or less, 40 g/( ^m2 ·day) or less, or 30 g/( ^m2 ·day) or less.

In particular, it is preferable for the transparent non-adsorptive layer to contain a polyester resin as the main component, from the viewpoint of achieving both non-adsorptive properties of the active ingredient and water vapor permeability.

The transparent non-adhesive layer may also contain other resins. Examples of other resins that can be used include acid-modified polyolefins.

The thickness of the transparent non-adhesive layer is preferably 1 μm or more, 2 μm or more, 3 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, or 30 μm or more from the viewpoint of improving non-adhesiveness, and is preferably 100 μm or less, 90 μm or less, 80 μm, 70 μm or less, 60 μm or less, or 50 μm or less from the viewpoint of ensuring moisture absorption.

Transparent skin layer
The transparent skin layer contains a resin for a transparent skin layer and can be present on the surface of the transparent moisture-absorbing layer opposite to the transparent barrier substrate layer. A transparent skin layer may also be present on the surface of the transparent moisture-absorbing layer facing the transparent barrier substrate layer. The transparent skin layer may also be fused to the transparent moisture-absorbing layer.

In particular, the transparent skin layer can prevent the moisture absorbent contained in the transparent moisture absorbing layer from falling off or coming into contact with the contents. In this case, the transparent skin layer may be a layer that does not contain a moisture absorbent.

The thickness of the transparent skin layer can be 1 μm or more, 3 μm or more, 5 μm or more, or 7 μm or more, and can be 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, or 15 μm or less. When multiple transparent skin layers are present, the thicknesses of each transparent skin layer can be the same or different.

(Resin for transparent skin layer)
As the resin for the transparent skin layer, the thermoplastic resins mentioned for the transparent substrate resin layer can be used alone or in combination, and among them, polyolefin resins, particularly polyethylene resins, are preferably used from the viewpoint of processability, etc. When skin layers are present on both sides of the transparent moisture absorbing layer, the resins for the transparent skin layers constituting the respective transparent skin layers may be the same or different.

Other Layers
The transparent moisture absorbing laminate may optionally have other layers, such as adhesive layers between the layers.

Packaging Bags
The packaging bag of the present invention comprises one or more sheets of the above-mentioned transparent moisture-absorbent laminate, and is formed into a bag shape by heat-sealing a portion of the one or more sheets of the transparent moisture-absorbent laminate opposite to the transparent barrier substrate layer side to another portion of the transparent moisture-absorbent laminate or another film. Here, the other film may be another transparent moisture-absorbent laminate or may be a film other than the transparent moisture-absorbent laminate.

The packaging bag of the present invention can be a content-containing packaging bag having the above-mentioned packaging bag and the contents stored in the packaging bag.

<Contents>
The contents are the contents stored in the packaging bag. The contents are not limited as long as they can deteriorate when exposed to the outside air, and examples of the contents include medicines, food, cosmetics, medical instruments, medical equipment, electronic parts, precision machinery, recording materials, etc. Furthermore, medicines include pharmaceutical preparations, cleaning agents, agricultural chemicals, etc.

The present invention will be specifically explained using examples and comparative examples, but the present invention is not limited to these.

<<Preparation of Laminate>>
<Transparent moisture absorbing film>
A two-kind, three-layer transparent moisture-absorbing film was produced by a co-extrusion T-die method in a multilayer film-forming machine, with the transparent skin layer, transparent moisture-absorbing layer, and transparent skin layer arranged in this order. A linear low-density polyethylene (LLDPE) was used as the transparent skin layer, and a resin composition was used as the transparent moisture-absorbing layer, which was prepared by melt-kneading 48 parts by mass of ethylene-vinyl acetate copolymer (EV150, Mitsui DuPont Polychemicals Co., Ltd.), 32 parts by mass of Na-A type zeolite (average particle size D50: 50 nm), and 5 parts by mass of an ester compound (propylene glycol monobehenate, HLB value 3.4) at a temperature of 160 ° C. for 10 minutes in a Banbury mixer. The thickness of each layer was 10 μm for the transparent skin layer, 30 μm for the transparent moisture-absorbing layer, and 10 μm for the transparent skin layer.

<Opaque moisture absorbing film>
An opaque moisture-absorbing film was prepared in the same manner as the transparent moisture-absorbing film, except that a resin composition prepared by melt-kneading 50 parts by mass of polyethylene and 50 parts by mass of hydrophilic zeolite (Molecular Sieve 4A, Union Showa Co., Ltd.) was used instead of the transparent moisture-absorbing layer of the transparent moisture-absorbing film.

<Transparent gas absorbing film>
A transparent gas-absorbing film was prepared in the same manner as the transparent moisture-absorbing film, except that a resin composition prepared by melt-kneading 99 parts by mass of polyethylene and 1 part by mass of a gas absorbent (Kesmon NS-20C, Toagosei Co., Ltd.) was used instead of the transparent moisture-absorbing layer of the transparent moisture-absorbing film.

<Opaque gas absorbing film>
An opaque gas-absorbing film was prepared in the same manner as the transparent moisture-absorbing film, except that a resin composition prepared by melt-kneading 80 parts by mass of polyethylene and 20 parts by mass of a gas absorbent (Abscents 3000, Union Showa Co., Ltd.) was used instead of the transparent moisture-absorbing layer of the transparent moisture-absorbing film.

<Transparent non-adhesive film>
A polyester film (Olyester, Toyobo Co., Ltd., thickness 25 μm) was prepared.

The haze was measured for each film produced.

The films prepared were bonded together using a urethane adhesive in the combinations shown in Table 1 to produce laminates for each of the examples and comparative examples.

"nature"
<Visibility>
Visibility is evaluated according to the following criteria.
A: The haze of the laminate is less than 50%.
x: The haze of the laminate is 50% or more.

<Moisture absorption>
The presence or absence of moisture absorption function is indicated according to the following criteria.
○: Moisture absorption function ×: No moisture absorption function

<Functionality>
The presence or absence of functionality other than moisture absorption is indicated according to the following criteria.
○: Has functions other than moisture absorption ×: Has no functions other than moisture absorption

The structures and properties of the examples and comparative examples are shown in Table 1.

From Table 1, it can be seen that the laminates of Examples 1 and 2 are transparent hygroscopic laminates that combine transparency, hygroscopicity, and functionality other than hygroscopicity.

Below, examples of transparent moisture-absorbing layers that can be used in the present invention are shown with reference to reference examples.

(Reference example: Transparent moisture absorbing film)
<Production Example>
Thermoplastic resin, Na-A type zeolite (average particle size D50: 50 nm), and ester compound (propylene glycol monobehenate, HLB value 3.4) were melt-kneaded at 160°C for 10 minutes using a Banbury mixer in the formulations shown in Tables 2 and 3 to obtain the resin compositions of each example.

<evaluation>
(Melt Flow Rate)
The resin composition of each example was cut to a size that could be measured. The melt flow rate (MFR) of the cut resin composition was measured using a melt indexer (Techno Seven Co., Ltd.) under conditions of a temperature of 190° C. and a load of 21.18 N in accordance with JIS K7210.

(Hayes)
The resin composition was cut to a predetermined weight, and a film having a thickness of 100 μm was produced by hot press molding. Here, the pressing conditions were a temperature of 160° C., a pressure of 40 to 60 MPa, and 2 minutes. The film thus obtained was cut into a 50 mm square, and the haze was measured in accordance with JIS K7105 using a haze meter (Murakami Color Research Institute Co., Ltd., HR-100). Regarding the haze after moisture absorption, the film was left to stand in an environment of 23° C. and 50% humidity until the weight change after moisture absorption became constant, and then the same method was used to measure the haze.

<result>
The configurations and evaluation results of each example are shown in Tables 2 and 3.

Referring to Table 2, it can be seen that the melt flow rate of the resin composition decreases significantly as the zeolite content increases. This tendency can also be confirmed in Reference Examples 3 and 4. In Reference Comparative Example 1, the melt flow rate had decreased to such an extent that molding by the T-die method or the inflation method was impossible.

Referring to Table 3, it was found that as the content of the ester compound decreased, the melt flow rate of the resin composition decreased significantly and the haze increased. In Reference Comparative Example 2, the melt flow rate was decreased to such an extent that molding by the T-die method or the inflation method was impossible, and the transparency was also decreased.

Reference Signs List 100 Transparent moisture absorbing laminate 12 Transparent barrier substrate layer 122 Transparent barrier layer 124 Transparent substrate resin layer 14 Transparent moisture absorbing layer 16 Transparent skin layer 18 Transparent functional layer

Claims (10)

A transparent barrier substrate layer, a transparent moisture-absorbing layer, and a transparent functional layer in this order, or a transparent barrier substrate layer, a transparent functional layer, and a transparent moisture-absorbing layer in this order, and the transparent moisture-absorbing layer contains a polyolefin resin, a zeolite having an average particle size D50 of 300 nm or less, and an ester compound having an HLB value of 5 or less, and
The transparent moisture absorbing layer contains 0% by mass of oxides (excluding zeolite) of one or more elements selected from Al, Si, Ti, and Zr having an average particle diameter D50 of 100 nm or less.
Transparent moisture absorbing laminate. 2. The transparent moisture-absorbing laminate according to claim 1, wherein the resin composition constituting the transparent moisture-absorbing layer has a melt flow rate of 1.0 g/10 min or more when measured in accordance with JIS K7210 under conditions of a temperature of 190° C. and a load of 21.18 N. 3. The transparent moisture-absorbing laminate according to claim 1, wherein the content of the zeolite is 40 mass % or less based on the total mass of the transparent moisture-absorbing layer. 4. The transparent moisture-absorbing laminate according to claim 1, wherein the content of the ester compound is 5.0% by mass or more based on the total mass of the transparent moisture-absorbing layer. 5. The transparent moisture-absorbing laminate according to claim 1, further comprising a transparent skin layer laminated on one or both sides of the transparent moisture-absorbing layer. The transparent moisture-absorbing laminate according to any one of claims 1 to 5 , wherein the transparent functional layer is a transparent gas-absorbing layer. The transparent moisture-absorbing laminate according to any one of claims 1 to 5 , wherein the transparent functional layer is a transparent non-adsorptive layer. The transparent moisture-absorbing laminate according to any one of claims 1 to 5 , wherein the transparent functional layer is a transparent easily peelable layer. The device comprises one or more transparent moisture-absorbing laminates according to any one of claims 1 to 8 , and a portion of the transparent moisture-absorbing laminates opposite to the transparent barrier substrate layer side is heat-sealed to another portion of the transparent moisture-absorbing laminate or another film to form a bag shape.
Packaging bag. The packaging bag according to claim 9 ; and a content-containing packaging bag having a content contained in the packaging bag.

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