JP7532759B2 - Outgassing absorbing packaging material for liquid electrolyte type lithium ion batteries - Google Patents

Description

The present invention relates to a packaging material having outgas absorbing properties for packaging a liquid electrolyte lithium ion battery, which absorbs outgas generated from the liquid electrolyte lithium ion battery, and a package obtained by packaging a liquid electrolyte lithium ion battery with the packaging material.
The packaging material for liquid electrolyte lithium ion batteries of the present invention can be applied to liquid electrolyte lithium ion battery products in various fields, and can be particularly suitably used as a packaging material for packaging large-capacity liquid electrolyte lithium ion batteries for use in home storage battery systems, power sources for automobile electric motors, and the like.

Conventionally, packaging materials for packaging lithium-ion batteries have been required to have improved properties such as airtightness and water vapor barrier properties to prevent the intrusion of water vapor from the outside, chemical resistance to prevent electrolyte leakage, and heat resistance to prevent melting and electrolyte leakage when the lithium-ion battery generates heat (Patent Document 1).
However, in recent years, when it is assumed that lithium-ion battery packages will be used for long periods of time, such as approximately 20 years, for example in vehicle or home use, there has been concern that in the case of liquid electrolyte lithium-ion batteries, outgassing, such as lower hydrocarbons such as ethylene, carbon monoxide, and carbon dioxide, which are produced by decomposition of the electrolyte during charging, will accumulate, causing the lithium-ion battery package to expand or break.
As a method for removing ethylene gas generated from the contents of a package, a method has been proposed in which potassium permanganate, which has the ability to decompose ethylene gas, is packed together with the contents to decompose and remove the ethylene gas (Patent Document 2). However, potassium permanganate has problems in terms of safety and hygiene, and there is a risk of it causing unexpected chemical reactions to proceed.
Also, a method has been proposed in which a physical absorbent such as zeolite or activated carbon is blended into a packaging material to absorb and remove ethylene gas generated from the contents (Patent Document 3), but this method does not provide a sufficient effect.
Furthermore, a method has been proposed in which ethylene monooxygenase is incorporated into a packaging material to biochemically metabolize and decompose ethylene gas (Patent Document 4). However, the conditions under which ethylene monooxygenase can be maintained in an active state are limited, and sufficient effects have not been obtained.

JP 2015-38881 A Japanese Patent Application Laid-open No. 54-117060 Japanese Unexamined Patent Publication No. 64-31838 Patent No. 3250196

The present invention aims to solve the above problems and provide an outgassing absorbing packaging material for liquid electrolyte lithium ion batteries that has excellent manufacturability and a simple layer structure, while absorbing outgassing such as organic gases (e.g., alkanes, alkenes, aldehydes, ketones, and organic acids), carbon monoxide, and carbon dioxide that are generated during the use of a liquid electrolyte lithium ion battery, and an outgassing absorbing liquid electrolyte lithium ion battery package obtained by packaging a liquid electrolyte lithium ion battery with the outgassing absorbing packaging material.

After extensive investigations, the inventors have discovered that an outgassing absorbing packaging material for liquid electrolyte lithium ion batteries containing a thermoplastic resin and a specific outgassing absorbent achieves the above-mentioned objective.

That is, the present invention is characterized in the following points.
1. An outgassing absorbing packaging material for a liquid electrolyte type lithium ion battery that absorbs organic gases, carbon monoxide, and carbon dioxide, comprising:
The outgassing absorbing packaging material includes at least a base layer made of a base film, a gas barrier layer made of a gas barrier film, and a sealant layer made of an outgassing absorbing sealant film,
The outgassing absorbing sealant film contains an outgassing absorbent and a heat sealable resin,
The outgassing absorbent contains an outgassing physical absorbent and/or an outgassing chemical absorbent,
The BET specific surface area of the outgas physical absorbent is 50 m ² /g or more and 4000 m ² /g or less,
The content of the outgas absorbent in the layer containing the outgas absorbent is 0.5% by mass or more and 30% by mass or less.
Outgassing absorbing packaging materials.
2. The gas physical absorbent contains a metal-organic framework and/or a zeolite having a pore size of 0.1 nm or more and 2 nm or less.
2. The outgassing absorbing packaging material according to claim 1.
3. The gas physical absorbent further contains one or more selected from the group consisting of activated clay, sepiolite, and halloysite.
3. The outgassing absorbing packaging material according to 2 above.
4. The gas chemical absorbent is an alkali metal compound or an alkaline earth metal compound.
4. An outgassing absorbing packaging material according to any one of 1 to 3 above.
5. The organic gas is one or more selected from the group consisting of alkanes, alkenes, aldehydes, ketones, and organic acids;
5. An outgassing absorbing packaging material according to any one of 1 to 4 above.
6. The base film contains a polyamide resin and/or a polyester resin.
6. An outgassing absorbing packaging material according to any one of 1 to 5 above.
7. The gas barrier film is an aluminum foil.
7. An outgassing absorbing packaging material according to any one of 1 to 6 above.
8. An outgassing packaging material made from any one of the outgassing absorbing packaging materials described in any one of 1 to 7 above.
Outgassing liquid electrolyte type lithium ion battery packaging.

The outgassing absorbing packaging material for liquid electrolyte lithium ion batteries of the present invention solves the above problems, has excellent manufacturability, and has a simple layer structure, while having excellent absorbency and heat sealability against outgassing such as organic gases such as alkanes, alkenes, aldehydes, ketones, and organic acids, carbon monoxide, and carbon dioxide that are generated when using liquid electrolyte lithium ion batteries, and is less likely to peel or swell due to the above outgassing generated from liquid electrolyte lithium ion batteries.

FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of an outgassing absorbing packaging material for a liquid electrolyte type lithium ion battery according to the present invention. FIG. 2 is a schematic cross-sectional view showing an example of a layer structure of another embodiment of the outgassing absorbing packaging material for a liquid electrolyte type lithium ion battery of the present invention. FIG. 2 is a schematic cross-sectional view showing one example of a layer structure of an outgassing absorbing packaging material for a liquid electrolyte type lithium ion battery according to another embodiment of the present invention.

In each drawing, the size and ratio of the components may be changed or exaggerated for ease of understanding. Also, for ease of understanding, parts that are not necessary for the explanation or repeated reference numerals may be omitted.
Although not shown in the drawings, an adhesive layer may be provided between each layer.
Furthermore, if necessary, in order to strengthen the adhesive strength (adhesion strength) between each layer, the laminated surfaces of each layer may be previously subjected to a physical surface treatment such as corona discharge treatment, ozone treatment, plasma treatment, glow discharge treatment, sandblasting treatment, etc., or a chemical surface treatment such as oxidation treatment using chemicals.

The outgassing absorbing packaging material for liquid electrolyte lithium ion batteries of the present invention will be described in more detail below. Specific examples will be given, but the present invention is not limited thereto.

(Gas to be absorbed)
In the present invention, the outgassing substances to be absorbed are organic gases, carbon monoxide, and carbon dioxide, and these outgases are contained in large amounts in the outgassing substances generated when a liquid electrolyte type lithium ion battery is used.
In the present invention, examples of organic gases include gases such as alkanes, alkenes, aldehydes, ketones, organic acids, etc. Furthermore, when the number of carbon atoms of these gases is 1 to 10, they are expressed as lower, and for example, organic gases are also described as lower organic gases.
Specific examples of alkanes include methane, ethane, propane, butane, pentane, hexane, septane, octane, nonane, and decane. Specific examples of alkenes include ethylene, propylene, butylene, pentene, hexene, septene, octene, nonene, and decene. Specific examples of aldehydes include methanal, ethanal, propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, and decanal. Specific examples of ketones include acetone, diethyl ketone, dipropyl ketone, dibutyl ketone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, and cyclohexanone. Specific examples of organic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, and oxalic acid.

<Liquid electrolyte lithium-ion battery>
A typical lithium-ion battery is composed of a positive electrode made of an oxide containing lithium, a negative electrode containing a carbon material, a separator, and an electrolyte.
Here, the electrolyte can be either liquid or solid, and a liquid electrolyte lithium-ion battery refers to a battery in which the electrolyte is a liquid.
Moreover, a typical lithium ion battery is a secondary battery that can be charged and discharged by the movement of lithium ions between a positive electrode and a negative electrode, and in the present invention, the lithium ion battery refers to such a secondary battery.
The above-mentioned liquid electrolyte (electrolyte solution) contains various Li salts and an organic solvent, and is prone to being reductively decomposed by the graphite in the negative electrode to generate decomposition gas. In particular, during the initial charge of a liquid electrolyte-type lithium-ion battery, a large amount of decomposition gas (outgassing) of the electrolyte solution is generated as a protective film (SEI, Li ion conductive film) is formed on the graphite surface.
The cumulative amount of outgassing generated in liquid electrolyte lithium-ion batteries for use in vehicles and home energy farms, which are expected to be used for more than 20 years, is extremely large, so there are concerns that the pouches used to package liquid electrolyte lithium-ion batteries may expand or tear due to outgassing, and measures to prevent this are necessary.

<Outgassing packaging material>
The outgassing absorbing packaging material of the present invention is suitable for use with liquid electrolyte type lithium ion batteries which generate a large amount of outgassing such as organic gases, carbon monoxide, and carbon dioxide during use.
The outgas absorbing packaging material of the present invention can absorb the above-mentioned outgas generated from a liquid electrolyte type lithium ion battery, thereby making it possible to suppress peeling or swelling of the liquid electrolyte type lithium ion battery packaging body.

The outgassing absorbing packaging material of the present invention comprises at least a base layer made of a base film, a gas barrier layer made of a gas barrier film, and a sealant layer made of an outgassing absorbing sealant film, the outgassing absorbing sealant film containing an outgassing absorbent and a heat sealable resin, and the outgassing absorbent contains an outgassing physical absorbent and/or an outgassing chemical absorbent.
The gas barrier layer is preferably laminated between the substrate layer and the outgas absorbing layer.
The outgassing absorbing packaging material may further include intermediate layers performing various functions, if necessary.
Furthermore, each layer constituting the outgas absorbing packaging material may be laminated via an adhesive layer.
The outgassing absorbing packaging material is a packaging material made from an outgassing absorbing laminate including the above-mentioned base layer, gas barrier layer, and sealant layer.
One surface of the outgas absorbing packaging material preferably has heat sealability, and therefore, it is preferable that the outgas absorbing sealant film is laminated so that the surface having heat sealability constitutes one surface of the outgas absorbing packaging material.
The outgas absorbing packaging material may further contain various plastic compounding agents and additives for the purpose of improving or modifying, for example, processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, mold releasability, flame retardancy, mold resistance, electrical properties, strength, etc. The content of these may be any amount ranging from a trace amount to several tens of percent depending on the purpose.
In the above, typical additives that may be contained include, for example, antiblocking agents, lubricants, crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, and the like.

<Sealant Layer>
The sealant layer is a layer containing an outgas absorbing agent and a heat sealable resin, and has outgas absorbing properties and heat sealability.
The sealant layer is preferably a layer made of an outgassing sealant film.
The outgassing absorbing sealant film is an outgassing absorbing film having heat sealing properties, and can be produced by incorporating a heat sealing resin into the outgassing absorbing film or by laminating a layer containing a heat sealing resin onto the outgassing absorbing film.
The sealant layer can impart outgassing properties to the outgassing absorbing packaging material by containing an outgassing absorbent, and can impart heat sealing properties to the outgassing absorbing packaging material by containing a heat sealing resin.
The outer surface of the sealant layer preferably has heat sealability by containing a heat sealable resin.
Furthermore, the sealant layer may further include a layer derived from other than the outgassing absorbing sealant film, if necessary. For example, it may further include a support layer for reinforcing the support.
The sealant layer may be of a single layer construction, or may be of a multi-layer construction consisting of two or more layers having the same or different compositions.
For example, it may be a single layer containing an outgas absorbent and a heat sealable resin, or it may be two layers, an outgas absorbing layer containing an outgas absorbent and a heat seal layer containing no outgas absorbent but a heat sealable resin. Furthermore, the outgas absorbing layer may be one or more of a layer containing only an outgas physical absorbent, a layer containing only an outgas chemical absorbent, and a layer containing both an outgas physical absorbent and an outgas chemical absorbent. Here, the outgas absorbing layer may contain a heat sealable resin.
The thickness of the sealant layer is not particularly limited, but is preferably 10 μm or more and 100 μm or less. If it is thinner than the above range, the rigidity is too low, it is easily torn, and it is difficult to exhibit a sufficient outgas absorbing effect, and if it is thicker than the above range, the rigidity is too high, and it is easy to deteriorate the usability as a packaging material or packaging material.

<Outgassing film>
The outgassing absorbing film is a gas absorbing film that absorbs lower organic gases, carbon monoxide, and carbon dioxide.

The outgas absorbing layer contains at least a thermoplastic resin and a specific outgas absorbing agent.
The outgas absorbing film exhibits outgas absorbing properties by containing an outgas absorbing agent, and the thermoplastic resin disperses the outgas absorbing agent and is contained as a resin component constituting the outgas absorbing film.
The outgas absorbing agent preferably contains an outgas physical absorbing agent, and may further contain an outgas chemical absorbing agent as necessary.
Furthermore, if necessary, the outgas absorbing film may further contain a heat sealable resin. By further containing a heat sealable resin, the outgas absorbing film can exhibit heat sealability.

The outgas absorbing film may be composed of one layer, or may be composed of two or more layers having the same or different compositions.
For example, there may be two layers, one containing an outgas absorbent (outgas absorbing layer) and the other not. In addition, there may be a layer containing only an outgas physical absorbent and a layer containing only an outgas chemical absorbent as the outgas absorbent, or there may be a layer containing both an outgas physical absorbent and an outgas chemical absorbent. In addition, there may be layers with different outgas absorbent contents.
The heat sealable resin may be contained in the outgas absorbing layer, or may be contained in a layer that does not contain an outgas absorbing agent to form a heat seal layer.
Furthermore, the outgas absorbing film may have a support layer for reinforcing support, if necessary.
The layers constituting the outgas absorbing film may be laminated via an adhesive layer.

The content of the outgas absorbent in the layer containing the outgas absorbent is preferably 0.5% by mass or more and 30% by mass or less, and more preferably 1% by mass or more and 29% by mass or less. If the content is less than the above range, there is a risk that sufficient outgassing absorption cannot be achieved, and if the content is more than the above range, there is a risk that the outgassing absorption will not be particularly improved, and interlayer adhesion and heat sealability may decrease, or the film may become brittle.

The outgas absorbing film may contain various plastic compounding agents and additives for the purpose of improving or modifying, for example, processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, releasability, flame retardancy, mold resistance, electrical properties, strength, etc. The content of these may be any amount ranging from a trace amount to several tens of percent depending on the purpose.
In the above, typical additives that may be contained include, for example, antiblocking agents, lubricants, crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, and the like.

There are no particular limitations on the thickness of the outgassing absorbing film, but it is preferably 10 μm or more and 100 μm or less. If it is thinner than the above range, it will have too little rigidity, be easily torn, and be difficult to exert a sufficient outgassing absorption effect, and if it is thicker than the above range, it will be too rigid and will be difficult to use as a packaging material or packaging supplies.

<Outgas absorbing layer>
The outgas absorbing layer is a layer containing an outgas absorbing agent and also contains a thermoplastic resin for dispersing the outgas absorbing agent. The outgas absorbing layer may also contain a thermoplastic resin having heat sealability, and if it has sufficient heat sealability, it can also function as a sealant layer.
Although there is no particular limitation on the thickness of the outgas absorbing layer, it is preferably 5 μm or more and 50 μm or less. If it is thinner than the above range, it is difficult to exhibit a sufficient outgas absorbing effect, and if it is thicker than the above range, the outgas absorbing effect is not improved significantly, and the rigidity of the outgas absorbing film becomes too strong, which tends to make it difficult to use as a sealant film or a packaging material.

<Outgas absorbent>
The outgassing absorbent can include an outgassing physical absorbent and/or an outgassing chemical absorbent.
By using various outgas absorbing agents in combination, for example, by using an outgas physical absorbing agent and an outgas chemical absorbing agent in combination, it becomes possible to easily absorb a variety of gases.
The outgas absorbent is used in the form of a powder, and the powder preferably has a number-based particle size D50 of 0.1 μm or more and 20 μm or less. If D50 is smaller than the above range, the gas physical absorbent is likely to aggregate, and if it is larger than the above range, the manufacturability and homogeneity of the film containing the outgas absorbent may be deteriorated, and the surface area of the outgas absorbent may be reduced, resulting in inferior gas absorption.

The outgas absorbing agent contained in the outgas absorbing layer is preferably contained via a master batch in which a powdered outgas absorbing agent is melt-blended with a thermoplastic resin.
Specifically, it is preferable to prepare a master batch by melt blending a powdered outgas absorbent into a thermoplastic resin at a relatively high concentration, and then dry blend the master batch with other components to achieve a desired concentration in the outgas absorbing layer.
The outgas absorbing agent and the thermoplastic resin to be melt blended may each be one type or two or more types.
The content of the outgas absorbent in the master batch is preferably 20% by mass or more and 90% by mass or less, and more preferably 30% by mass or more and 70% by mass or less. Within the above range, it is easy to include a necessary and sufficient amount of the outgas absorbent in the outgas absorbing layer in a dispersed state.

[Outgassing physical absorbent]
The outgas physical absorbent is a gas absorbent that has the function of physically absorbing the gas to be absorbed.
The BET specific surface area of the physical gas absorbent is preferably 50 m2/g or more and 4000 m2/g or less. If it is less than the above range, there is a risk that sufficient gas absorption cannot be exhibited, and it is difficult to make it larger than the above range.
The outgas physical absorbent preferably contains a metal-organic framework (MOF) and/or zeolite having a pore size of 0.1 nm or more and 2 nm or less.
If the pore diameter is smaller than the above range, it is difficult to absorb the gas to be absorbed inside the pores, and if it is larger than the above range, there is a risk that the selectivity of the gas to be absorbed will decrease due to the tendency to absorb gases other than the gas to be absorbed, and the gas to be absorbed once absorbed will be easily released.
The molecular radii (kinetic diameters) of the gases to be absorbed are as follows: carbon dioxide is approximately 0.33 nm, carbon monoxide is approximately 0.38 nm, methane is 0.38 nm, ethylene is 0.39 nm, propylene is 0.45 nm, 1-butene is 0.43 nm, and i-butene is 0.50 nm.
If necessary, one or more outgassing physical absorbents other than the organometallic structure and zeolite, selected from the group consisting of activated clay, sepiolite, and halloysite, can also be used in combination.

(Metal-Organic Frameworks)
As the metal organic framework (MOF), a salt composed of a metal ion and an organic ligand is preferably used.
The metal organic framework can have a porous structure with a smaller pore size and a larger specific surface area compared to common activated carbon or zeolite.
Specific examples of the organometallic structure in the present invention include aluminum fumarate, zirconium fumarate, copper trimesate, aluminum trimesate, zirconium trimesate, iron trimesate, aluminum terephthalate, zirconium terephthalate, 2-methylimidazole zinc, magnesium formate, zinc benzene-1,3,5-tribenzoate, zinc 2,6-naphthalene-dicarboxylate, aluminum aminobenzene-1,4-dicarboxylate, magnesium 2,5-dioxidobenzene-1,4-dicarboxylate, and magnesium 4,4-dioxidobiphenyl-3,3-dicarboxylate. One or more selected from these groups can be used.
The pore size of the metal-organic structure is preferably 0.3 nm or more and 3.0 nm or less, and more preferably 0.3 nm or more and 2.0 nm or less. For example, the pore size of 2-methylimidazole zinc salt is 1.1 nm and 0.6 nm, that of copper trimesate is 0.90 nm or 0.3 nm and 0.5 nm, that of aluminum terephthalate is 0.8 nm and 0.5 nm, that of aluminum fumarate is 1.1 nm and 0.5 nm, that of aluminum trimesate is 0.7 nm and 0.6 nm, that of zirconium trimesate is 0.46 nm, 1.15 nm, and 1.8 nm, that of magnesium formate is 0.3 nm and 0.4 nm, and that of iron trimesate is 2.5 nm and 2.9 nm.
The specific surface area of the metal-organic structure can be expressed as a BET specific surface area or a Langmuir specific surface area. In the case of the BET specific surface area, it is preferably 400 m ² /g or more and 4000 m ² /g or less, and more preferably 900 m ² /g or more and 2100 m ² /g or less.
In the case of the Langmuir specific surface area, it is preferably 500 m ² /g or more and 5000 m ² /g or less, and more preferably 1200 m ² /g or more and 2400 m ² /g or less.
For example, the BET specific surface areas of zinc 2-methylimidazole are 1,350 m ² /g, copper trimesate is 1,500 m ² /g, aluminum terephthalate is 950 m ² /g, aluminum fumarate is 1,000 m ² /g, aluminum trimesate is 1,100 m ² /g, zirconium trimesate is 2,060 m ² /g, magnesium formate is 400 m ² /g, and zinc benzene-1,3,5-tribenzoate is 3,600 m ² /g.
For example, the Langmuir specific surface areas are 1,800 m ² /g for zinc 2-methylimidazole, 2,000 m ² /g for copper trimesate, 1,500 m ² /g for aluminum terephthalate, 1,200 m ² /g for aluminum fumarate, 1,500 m ² /g for aluminum trimesate, 2,390 m ² /g for zirconium trimesate, 500 m ² /g for magnesium formate, and 5,000 m ² /g for zinc benzene-1,3,5-tribenzoate.

The above-mentioned organometallic structures can absorb gases in amounts corresponding to the molecular size and specific surface area of their pores. For example, 2-methylimidazole zinc salt is excellent at absorbing lower hydrocarbons and carbon dioxide, copper trimesate is excellent at absorbing lower hydrocarbons (especially methane) and carbon dioxide, aluminum terephthalate is excellent at absorbing methane, water, and carbon dioxide, aluminum fumarate and zircon trimesate are excellent at absorbing water, and aluminum trimesate is excellent at absorbing lower hydrocarbons (especially methane) and water.

In the present invention, among the above-mentioned organometallic structures, it is preferable to use one or more selected from the group consisting of 2-methylimidazole zinc salt, copper trimesate, and aluminum terephthalate.

(Zeolite)
The zeolite preferably contains CHA type zeolite or MFI type zeolite.
Here, the pore size is preferably about 0.38 nm for CHA type zeolite, and about 0.55 nm for MFI type zeolite.
The BET specific surface area of the MFI zeolite is preferably from 300 to 500 m ² /g.
The above zeolites can absorb gases in amounts corresponding to the molecular size and specific surface area of the pores. For example, CHA-type zeolites are excellent in absorbing lower hydrocarbons and carbon dioxide, while MFI-type zeolites are excellent in absorbing carbon dioxide, lower hydrocarbons, lower aldehydes, lower organic acids, and lower alcohols.

(Activated clay)
Activated clay is a type of clay that is obtained by heat treating acid clay or bentonite, which is mainly composed of naturally occurring montmorillonite, with sulfuric acid or hydrochloric acid, washing with water, and drying. It is porous, has a large specific surface area, and is highly absorbent.
Activated clay with a pore size of 5 to 17 nm is readily available and is preferred.
The activated clay preferably has a large specific surface area, and although there is no particular restriction on the specific surface area, those with a specific surface area of 50 to 400 m ² /g are preferred as they are easily available. The pH (5% suspension) is preferably 3.0 to 5.0, more preferably 3.3 to 4.0.

(Sepiolite)
Sepiolite is a clay mineral whose main component is hydrated magnesium silicate, and has a porous structure with a general chemical composition of Mg ₈ Si ₁₂ O ₃₀ (OH ₂ ) ₄ (OH) _{4.6-8H 2} O. From the viewpoint of availability, the pH (3% suspension) is preferably 8.0-9.0, and more preferably 8.9-9.3.

(Halloysite)
Halloysite is a type of kaolin mineral, and its general chemical composition is expressed as Al ₂ Si ₂ O ₅ (OH) _{4.2H 2} O. It has a nanotube structure with an outer diameter of 50-70 nm and an inner diameter of 15-30 nm, and a BET specific surface area of about 65 m ² /g.

[Outgassing chemical absorber]
The outgassing chemical absorbent is a gas absorbent that has the function of chemically absorbing or decomposing the gas to be absorbed.
In addition, since the absorption or decomposition is chemical, the gas molecules are less likely to be affected by water and are less likely to desorb once absorbed, allowing for efficient absorption. Furthermore, the decomposition products are absorbed by an outgassing physical absorbent or an outgassing chemical absorbent.
In the present invention, it is preferable to use an alkali metal compound or an alkaline earth metal compound as the outgas chemical absorbent.
Examples of the alkali metal compound include alkali metal oxides, alkali metal chlorides, and alkali metal hydroxides, and specific examples of the alkali metal compound include Li ₂ O, Na ₂ O, K ₂ O, LiCl, LiOH, etc. Among these, Na ₂ O and K ₂ O are preferred.
Examples of the alkaline earth metal compound include alkaline earth metal oxides, alkaline earth metal chlorides, alkaline earth metal hydroxides, etc., and specific examples of the alkaline earth metal compound include BeO, MgO, CaO, SrO, BaO, RaO, MgCl ₂ , CaCl ₂ , Mg(OH) ₂ , Ca(OH) ₂ , etc. Among these, MgO and CaO are preferred.

[Thermoplastic resin]
There are no particular limitations on the thermoplastic resin contained together with the outgas absorbent, so long as it has excellent dispersibility for the gas physical absorbent and can withstand use as a packaging material.
The thermoplastic resin may also contain a heat-sealable resin.
The thermoplastic resin preferably contains a polyolefin resin.
Specific examples of polyolefin resins include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylic acid copolymer, ethylene-propylene copolymer, and mixtures of these resins.
Among the above, polyethylene-based resins are preferred, and among the polyethylene-based resins, LDPE, LLDPE, general-purpose PE, PE-based copolymers, etc. are more preferred, with LLDPE being even more preferred.

[Heat sealable resin]
The heat-sealable resin is not particularly limited, and any known resin can be used as long as it can be melted and fused by heat.
Specific examples of heat-sealable resins include polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, metallocene polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-ethyl (meth)acrylate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-propylene copolymer, methylpentene polymer, polyolefin resins obtained by modifying polyolefin resins such as polyethylene or polypropylene with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, and the like, terpolymer resins of ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid, cyclic polyolefin resins, cyclic olefin copolymers, polyethylene terephthalate (PET), polyacrylonitrile (PAN), and the like.
Among these, polyolefin resins are preferred, polyethylene resins are more preferred, and low-density polyethylene and linear low-density polyethylene are even more preferred.

[Heat seal layer]
The heat seal layer is a layer that contains a heat sealable resin and has sufficient heat sealability, and may or may not contain an outgas absorbing agent.

[Support layer]
The support layer is a layer that is included as necessary, and is included, for example, to supplement the rigidity of the outgas absorbing film and can also have the effect of preventing blocking when the outgas absorbing film is rolled or stacked.
The resin contained in the support layer is preferably LDPE or LLDPE, and may also contain a heat-sealable resin.
The thickness of the support layer is not particularly limited, but is preferably 1 μm or more and 50 μm or less. If it is thinner than the above range, it is difficult to exert the effect of reinforcing rigidity, and if it is thicker than the above range, the rigidity is too strong and it is likely to become difficult to use as a packaging material or packaging material.

<Adhesive Layer>
There are no particular limitations on the adhesive used in the adhesive layer, and adhesives for dry lamination, adhesives for EC (extrusion coating), adhesives for non-solvent lamination, any anchor coating agent, and the like can be used.
The adhesive may be of any of the following types: heat-curable, ultraviolet-curable, and electron-beam-curable types; and may be in any form, such as aqueous, solution, emulsion, and dispersion types. The adhesive may be in any form, such as film/sheet, powder, and solid. The adhesive mechanism may be any of the following types: chemical reaction, solvent volatilization, thermal melting, and thermal pressure.

Examples of components that form such adhesive layers include polyvinyl acetate adhesives such as polyvinyl acetate and vinyl acetate-ethylene copolymers, polyacrylic acid adhesives consisting of copolymers of polyacrylic acid and polystyrene, polyester, polyvinyl acetate, etc., cyanoacrylate adhesives, ethylene copolymer adhesives consisting of copolymers of ethylene and monomers such as vinyl acetate, ethyl acrylate, acrylic acid, and methacrylic acid, cellulose adhesives, polyurethane adhesives, polyester adhesives, polyamide adhesives, polyimide adhesives, polyolefin adhesives such as LDPE, amino resin adhesives consisting of urea resin or melamine resin, phenol resin adhesives, epoxy adhesives, reactive (meth)acrylic adhesives, elastomer adhesives consisting of chloroprene rubber, nitrile rubber, styrene-butadiene rubber, etc., silicone adhesives, inorganic adhesives consisting of alkali metal silicates, low melting point glass, etc.

<Outgassing sealant film>
The outgassing absorbing sealant film is a sealant film produced using an outgassing absorbing film, and has outgassing absorbency similar to that of the outgassing absorbing film, and excellent heat sealability.
When the outgas absorbing film has sufficient heat sealability and supportability, the outgas absorbing film can be used as it is as an outgas absorbing sealant film, and if necessary, an outgas absorbing sealant film can be produced by further laminating a support layer thereon, incorporating a heat sealable resin therein, or laminating a layer containing a heat sealable resin therein.

The outgassing absorbing sealant film may have a single layer structure or a multi-layer structure having two or more layers.
In the case of a multi-layer structure, if the layer derived from the outgas absorbing film does not have sufficient supportability or heat sealability, a support layer or a heat seal layer can be laminated to prepare an outgas absorbing sealant film. If necessary, various functional layers can be further laminated to prepare an outgas absorbing sealant film. Here, each layer constituting the outgas absorbing sealant film may be laminated via an adhesive layer.
One or both surfaces of the outgassing absorbing sealant film preferably have heat sealability, and for this purpose, for example, a heat seal layer may be laminated on one or both surfaces of the outgassing absorbing sealant film.
By providing the outgas absorbing sealant film with heat sealability on both sides, it is possible to produce an outgas absorbing laminate having excellent internal interlayer adhesion and heat sealability.

There is no particular limit to the thickness of the outgassing sealant film, but it is preferably 10 μm or more and 100 μm or less. If it is thinner than the above range, it will have too little rigidity, be easily torn, and be difficult to exert a sufficient gas absorption effect, and if it is thicker than the above range, it will be too rigid and will be difficult to use as a packaging material or packaging supplies.

<Method of producing outgassing absorbing film and outgassing absorbing sealant film>
The preparation method described below is merely an example and is not intended to limit the present invention.
There are no particular limitations on the method for forming and laminating the outgas absorbing film or outgas absorbing sealant film and the layers that constitute them, and any known or commonly used film forming and laminating method can be used.
The outgas absorbing film or outgas absorbing sealant film can be produced by a known film forming method and/or lamination method such as (co)extrusion, cast molding, T-die method, cutting method, inflation method, etc.
When the outgassing absorbing film or outgassing sealant film is composed of two or more layers, for example, films constituting each layer that have been prepared in advance may be laminated via an adhesive layer, a molten resin composition may be laminated onto a layer that has been prepared in advance by (co)extrusion, a plurality of layers may be simultaneously prepared and laminated by melt pressure bonding, or one or more types of resins may be applied and dried to coat another layer.
For example, an outgassing absorbing sealant film can be prepared by laminating a heat seal layer onto an outgassing absorbing film.

The outgas absorbing layer or the heat seal layer may be laminated on another layer by extrusion or co-extrusion, or may be laminated via an adhesive layer after film formation by inflation or casting. Even in the case of the extrusion coating method, an adhesive layer may be laminated as necessary.
Alternatively, a film for the outgas absorbing layer or a film for the heat seal layer that has been previously formed may be laminated and bonded via an adhesive layer that has been laminated by an extrusion coating method, a dry lamination method, a non-solvent lamination method, or the like.
Then, an aging treatment may be carried out as necessary.

For example, in the case of laminating an outgas absorbing layer or a heat seal layer by an extrusion coating method, first, the resin composition forming the layer is heated and melted, and expanded and stretched in the required width direction using a T-die to be (co)extruded in a curtain shape, and the molten resin is caused to flow down onto the surface to be laminated and sandwiched between a rubber roll and a cooled metal roll, thereby simultaneously forming the layer and laminating and adhering to the surface to be laminated.
When laminating layers by extrusion coating, the melt flow rate (MFR) of the resin component contained in each layer is preferably 0.2 to 50 g/10 min, more preferably 0.5 to 30 g/10 min. If the MFR is smaller or larger than the above range, the processing suitability is likely to be poor. In this specification, the MFR is a value measured by a method based on JIS K7210.

When using the inflation method, the melt flow rate (MFR) of the resin component contained in each layer is preferably 0.2 to 10 g/10 min, and more preferably 0.2 to 9.5 g/10 min. If the MFR is smaller or larger than the above range, the processing suitability is likely to be inferior.

Furthermore, in order to improve adhesion between the layers constituting the outgas absorbing film or the outgas absorbing sealant film, the surface of each layer may be subjected to a desired surface treatment in advance, if necessary.
For example, a corona-treated layer, an ozone-treated layer, a plasma-treated layer, an oxidation-treated layer, or the like can be formed by optionally carrying out pretreatment such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen outgas or nitrogen outgas, or the like, glow discharge treatment, or oxidation treatment using chemicals or the like.
Alternatively, various coating layers such as a primer coating layer, an undercoating layer, an anchor coating layer, an adhesive layer, and a vapor-deposited anchor coating layer may be optionally formed on the surface to form a surface treatment layer.
For the various coating agent layers, for example, a resin composition containing a polyester-based resin, a polyamide-based resin, a polyurethane-based resin, an epoxy-based resin, a phenol-based resin, a (meth)acrylic resin, a polyvinyl acetate-based resin, a polyolefin-based resin such as polyethylene or polypropylene, or a copolymer or modified resin thereof, a cellulose-based resin, or the like as a main component of the vehicle can be used.

Each layer constituting the outgassing absorbing film or outgassing absorbing sealant film can be further uniaxially or biaxially stretched by a conventionally known method using a tenter method, a tubular method, or the like, as necessary.

<Outgassing laminate>
The outgas absorbing laminate of the present invention is a laminate obtained by laminating the outgas absorbing film of the present invention or the outgas absorbing sealant film of the present invention with, for example, a base layer or a gas barrier layer, and has outgas absorbing properties similar to those of the outgas absorbing film.
The outgassing laminate may further include intermediate layers performing various functions, as required.
One surface of the outgas absorbing laminate is preferably a heat seal layer so that the outgas absorbing laminate has heat sealability.
The gas barrier layer is preferably laminated between the substrate layer and the outgas absorbing layer.
Furthermore, the layers constituting the outgas absorbing laminate may be laminated via an adhesive layer.
Then, an aging treatment may be carried out as necessary.

The outgas absorbing laminate or each layer constituting the outgas absorbing laminate may contain various plastic compounding agents and additives for the purpose of improving or modifying, for example, processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, releasability, flame retardancy, mildew resistance, electrical properties, strength, etc. The content of such agents may be any amount ranging from a trace amount to several tens of percent depending on the purpose.
In the above, typical additives that may be contained include, for example, antiblocking agents, lubricants, crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, and the like.

<Base layer>
The material of the substrate layer may be a commonly known substrate film having excellent mechanical, physical, chemical, and other properties, particularly strength, toughness, and heat resistance. As the substrate film, various resin films may be used, and further, various paper substrates may be used, and a resin film and a paper substrate may be used in combination.
The substrate layer may be composed of one layer, or may be composed of two or more layers of the same or different compositions laminated by any lamination means.
The thickness of the base material layer can be appropriately set by a person skilled in the art. For the purpose of imparting appropriate strength and stiffness to the laminate, the thickness of the base material layer is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm, and even more preferably 5 to 25 μm.

Specific examples of the resin film include resin films made of tough thermoplastic resins such as polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefin-based resins such as polypropylene, polyamide-based resins such as nylon, polyaramid-based resins, polycarbonate-based resins, polyacetal-based resins, fluorine-based resins, and others.
The resin film may be either an unstretched film or a uniaxially or biaxially stretched film.
Among the above, resin films containing polyester-based resins and/or polyamide-based resins are preferred, and biaxially oriented PET films and biaxially oriented nylon films are more preferably used.

The paper base material can provide properties such as shapeability, flex resistance, and rigidity. For example, a strong sizing bleached or unbleached paper base material for a paper layer, or a paper base material such as pure white roll paper, kraft paper, paperboard, processed paper, milk base paper, and others can be used.
The paper base material preferably has a basis weight of about 30 g/m ² to 600 g/m ² , and more preferably has a basis weight of about 50 g/m ² to 450 g/m ² .

If necessary, plastic compounding agents and additives such as lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, and pigments may be added to the resin film used for the base layer for the purpose of improving or modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, release properties, flame retardancy, mildew resistance, electrical properties, strength, and the like. The amount of these additives may be arbitrarily added depending on the purpose as long as it does not adversely affect other performance properties.
A printed layer may be provided on one or both sides of the base layer.

<Printed layer>
The printed layer visually presents design patterns such as letters, numbers, figures, symbols, pictures, patterns, etc. for the purpose of decoration, indication of contents, indication of expiration date, indication of manufacturer, seller, etc., and for imparting aesthetic appeal, and can form the desired design pattern.
The printed layer is preferably formed on one or both sides of the base layer by a printing method such as gravure printing or flexographic printing. The printed layer may be provided on the entire surface of the printed surface, or may be provided on only a part of the surface.
By forming the printed layer inside the laminate, the adhesion of the printed layer can be improved, and the ink on the printed layer can be prevented from being rubbed off or peeled off due to external impact or friction.
When the printed layer is present inside the laminate, it is preferable that the layer that is on the outer side of the printed layer when the package is formed is transparent so that the printed layer can be visually confirmed.

<Gas Barrier Layer>
The gas barrier layer is a layer that suppresses the permeation of gas, and when a gas absorbing package is produced, it can suppress the intrusion of oxygen and water vapor from the outside of the outgas absorbing package into the content storage section inside the package and can suppress the diffusion of outgas components generated from the content to the outside of the gas barrier layer. Also, the permeation of the gas to be absorbed in the present invention can be suppressed in the same manner.
Various barrier materials can be used for the gas barrier layer. In addition, the barrier material may have a light-shielding property against sunlight and the like, an aroma-retaining property for the contents, etc., in addition to oxygen and water vapor. In addition, a barrier material having a gas barrier property against water vapor and the like, a light-shielding property against sunlight and the like, an aroma-retaining property for the contents, etc., may be used in combination.

As the above-mentioned barrier material, it is preferable to use a gas barrier film. Specifically, for example, one or more types selected from the group consisting of a metal foil, a resin film having an inorganic vapor deposition layer, and a resin coating film or resin film made of an oxygen barrier resin can be used.
In particular, a resin film having a metal vapor deposition layer, a resin film having a metal oxide vapor deposition layer, or a resin coating film or film made of a barrier resin is preferred, as it has excellent barrier properties against oxygen gas, water vapor, light blocking, aroma retention, etc., and is environmentally friendly in terms of disposal of the container.

A specific example of the metal foil is aluminum foil, and the thickness of the aluminum foil is preferably 5 μm to 30 μm.
Examples of inorganic compounds that form the inorganic vapor deposition layer include metals, metal oxides, metal nitrides, and metal carbides.
Specific examples of metal elements constituting the above inorganic compounds include aluminum (Al), silicon (Si), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), zinc (Zn), vanadium (V), barium (Ba), and chromium (Cr).

Other examples include composite inorganic compounds such as indium tin oxide (ITO) and SiO _x C _y films prepared by chemical vapor deposition.

As the inorganic material to be vapor-deposited for use in the resin film having a vapor-deposited layer, silicon oxide and aluminum oxide are preferred.
The average composition of inorganic compounds is expressed as _MOx , _MOxCy (wherein M represents a metal element, and the values of x and _y vary depending on the metal element), such as _SiOx , _AlOx , _SiOxCy , _etc. In the case of metal oxides, the value of X can range, for example, from 0 to 2 for silicon, 0 to 1.5 for aluminum, 0 to 1 for magnesium, 0 to 1 for calcium, 0 to 0.5 for potassium, 0 to 2 for tin, 0 to 0.5 for sodium, 0 to 1.5 for boron, 0 to 2 for titanium, 0 to 1 for lead, 0 to 2 for zirconium, and 0 to 1.5 for yttrium.
In the above _MOx , when x=0 it is, for example, a metal, and the upper limit of the range of x is the value when it is completely oxidized.

For packaging material applications, silicon oxide and aluminum oxide are preferably used, and it is preferable to use silicon oxide with x in the range of 1.0 to 2.0, and aluminum oxide with x in the range of 0.5 to 1.5.
The gas barrier layer may be formed of one of these barrier materials, or may be a combination of two or more of them, or may be a mixture of two or more of them. It may be composed of one layer or multiple layers of the same or different compositions, and in the case of multiple layers, they do not have to be laminated adjacently.

The resin film that supports the above-mentioned deposition layer can be a resin film that has excellent mechanical, physical, chemical, and other properties, and is particularly strong and tough, as well as heat-resistant, since the deposition layer is provided on it.

Specifically, in the present invention, examples of the resin film supporting the deposition layer include polyester-based resin films such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polyamide-based resin films such as various nylons, polyethylene-based resins, polypropylene-based resins, cyclic polyolefin resins, polystyrene-based resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), polyolefin films such as polybutene resin films, polyvinyl chloride-based resins, polycarbonate-based resins, polyimide-based resins, polyamideimide-based resins, polyarylphthalate resins, silicone-based resins, polysulfone-based resins, polyphenylene sulfide-based resins, polyethersulfone-based resins, polyurethane-based resins, cellulose-based resins, poly(meth)acrylic resins, polyvinylidene chloride films, acetal-based resin films, fluorine-based resins, and others.
In the present invention, it is particularly preferable to use a film made of a polypropylene resin, a polyester resin, or a polyamide resin.

Methods for forming an inorganic vapor deposition layer include using the inorganic compounds as described above as raw materials and using physical vapor deposition methods (Physical Vapor Deposition, PVD methods) such as vacuum deposition, sputtering, ion plating, cluster ion beam methods, etc., or chemical vapor deposition methods (Chemical Vapor Deposition, CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, photochemical vapor deposition, etc. to form a vapor deposition layer on a resin film.

More specifically, in the above-mentioned PVD method, for example, a winding deposition machine is used, and the resin film coming off the unwinding roll in a vacuum chamber is placed in a deposition chamber, where the deposition source heated in a crucible is evaporated, and if necessary, an inorganic deposition layer is formed through a mask on the resin film on a cooled coating drum while oxygen or the like is blown out from an oxygen outlet, and then the resin film with the inorganic deposition layer formed thereon is wound up on a take-up roll, thereby producing a resin film having an inorganic deposition layer according to the present invention.

On the other hand, in the above-mentioned CVD method, a resin film can be produced in which an inorganic vapor deposition layer such as silicon oxide is formed by plasma by introducing a mixed gas of, for example, an organic silicon compound as a monomer gas, oxygen gas, and an inert gas supplied from a vapor deposition raw material volatilization supply device onto the surface of a resin film unwound from a winding roll arranged in a vapor deposition chamber, on the peripheral surface of the electrode drum. In the present invention, the resin film having the inorganic vapor deposition layer as described above prevents oxygen gas or water vapor from passing through, and functions as a gas barrier layer against these.

In the above, the thickness of the vapor deposition layer is preferably 30 Å to 3000 Å, more preferably 40 Å to 2500 Å, and even more preferably 50 Å to 2000 Å, in order to obtain sufficient barrier properties.
More specifically, in the above PVD method, the thickness of the vapor-deposited layer of aluminum oxide is preferably 30 Å to 1000 Å, and more preferably about 50 Å to 500 Å.
In the above CVD method, the thickness of the vapor-deposited layer of silicon oxide is preferably 30 Å to 3000 Å, and more preferably 50 Å to 2000 Å.
In the above, in the case of a vapor-deposited layer made of a metal oxide or an inorganic substance, if the thickness of the vapor-deposited layer exceeds the above range, cracks or the like are likely to occur in the vapor-deposited layer, and there is a risk that the barrier properties will be reduced due to warping, and there are problems such as high material costs, which are undesirable. Also, if the thickness is less than the above range, it is undesirable because it becomes difficult to exhibit the barrier properties.

Furthermore, the resin film having an inorganic vapor deposition layer has a water vapor permeability measured in accordance with JIS K7129 at a temperature of 40° C. and a humidity of 100% RH of preferably 3.0 g/ ^m2 ·day or less, more preferably 2.0 g/ ^m2 ·day or less, and even more preferably 1.5 g/ ^m2 ·day or less. If the water vapor permeability falls within the above numerical range, the intrusion of water vapor from the outside of the package into the content storage section inside the package can be sufficiently suppressed.
Furthermore, the resin film having an inorganic vapor deposition layer has an acid permeability measured in accordance with JIS K7126 under an environment of a temperature of 23° C. and a humidity of 90% RH of preferably 3.0 cc/ ^m2 ·atm·day or less, more preferably 2.0 cc/ ^m2 ·atm·day or less, and even more preferably 1.0 cc/ ^m2 ·atm·day or less. If the oxygen permeability satisfies the above numerical range, the intrusion of oxygen from the outside of the package into the content-accommodating portion inside the package can be sufficiently suppressed.

A barrier resin coating film or a barrier resin film made of a barrier resin can also be used as a barrier material and can also exhibit aroma retention and the like.
Examples of the barrier resin that can be used include films or coatings of resins with excellent gas barrier properties, such as polyvinylidene chloride resins (PVDC), polyester resins, polyamide resins (particularly aromatic polyamides such as nylon MXD6), ethylene-vinyl alcohol copolymers (EVOH) having an ethylene content of 25 mol % to 50 mol % obtained by fully saponifying an ethylene-vinyl acetate copolymer (vinyl acetate is approximately 79 wt % to 92 wt %), polyvinyl alcohol, polyacrylonitrile, and the like.
The thickness of the barrier resin coating film or the barrier resin film is not limited, but is preferably 0.5 μm to 300 μm, and more preferably 1 μm to 100 μm.
As the gas barrier film, a metal foil or a resin film having a vapor deposition layer is preferred, and an aluminum foil is particularly preferred.

<Method of Producing Outgas Absorbing Laminate>
For example, an example of producing an outgas absorbing laminate by laminating a base layer and a gas barrier layer on an outgas absorbing sealant film will be described. The production method shown below is only one example and does not limit the present invention.
The lamination of the base material layer and the gas barrier layer can be carried out by any method commonly used in the production of packaging materials, such as a wet lamination method, a dry lamination method, a solventless dry lamination method, an extrusion lamination method, a T-die coextrusion molding method, a coextrusion lamination method, an inflation method, or the like.
For example, an outgassing absorbing laminate can be obtained by laminating and adhering a substrate layer, a gas barrier layer, and an outgassing absorbing sealant film via an adhesive layer laminated by an extrusion coating method, a dry lamination method, a non-solvent lamination method, or the like.

When laminating by the extrusion coating method, first, the resin composition that forms the adhesive layer is heated and melted, and then expanded and stretched in the required width direction using a T-die to be (co)extruded in a curtain shape. The molten resin is then caused to flow down onto the surface to be laminated and sandwiched between a rubber roll and a cooled metal roll, thereby simultaneously forming the adhesive layer and laminating and adhering to the surface to be laminated.
Alternatively, for example, first, a dry lamination adhesive is applied to one side of a resin film for the base layer, the film is dried, and the film is adhered and laminated to the barrier layer, and then a dry lamination adhesive is applied to the surface of the barrier layer, the film is dried, and the film is adhered and laminated to the outgassing absorbing sealant film to obtain an outgassing absorbing packaging material.
Then, an aging treatment may be carried out as necessary.
In this manner, an outgas absorbing laminate can be obtained.

<Outgassing liquid electrolyte type lithium ion battery packaging>
An outgassing-absorbing liquid electrolyte-type lithium ion battery packaging body is a packaging body produced by packaging a liquid electrolyte-type lithium ion battery using an outgassing-absorbing packaging material, and has outgassing absorbing properties similar to those of the outgassing-absorbing packaging material.
In an outgassing-absorbing liquid electrolyte-type lithium ion battery packaging, even if gas to be absorbed is generated from the liquid electrolyte-type lithium ion battery, the gas to be absorbed is absorbed by the outgassing-absorbing packaging material that constitutes the outgassing-absorbing liquid electrolyte-type lithium ion battery packaging, so that peeling or swelling is unlikely to occur in the outgassing-absorbing liquid electrolyte-type lithium ion battery packaging.

<Ingredients>
The main raw materials used in the examples of the present invention are as follows:

<Outgas absorbent>
[Outgassing physical absorbent]
MOF1: Metal-organic framework, 2-methylimidazole zinc. Pore sizes 1.1 nm and 0.6 nm, D50 particle size 4.9 μm.
MOF2: Metal organic framework, copper trimesate, pore size 0.90 nm or 0.3 nm and 0.5 nm, D50 particle size 15.96 μm.
MOF3: metal-organic framework, aluminum terephthalate salt, pore size 0.8 nm and 0.5 nm, prepared by pulverizing with a jet mill to a D50 particle size of 20 μm or less.
Zeolite 1: CHA type zeolite. Pore size 0.38 nm, prepared by pulverizing with a jet mill to a D50 particle size of 20 μm or less.
Zeolite 2: MFI type zeolite. SiO ₂ /Al ₂ O ₃ molar ratio = 400/1. Pore size 0.55 nm, D50 particle size 5 to 7 μm.

[Outgassing chemical absorber]
Alkaline earth metal compound 1: calcium hydroxide. D50 particle size 5 μm.

[Thermoplastic resin, heat sealable resin]
LLDPE1: LLDPE, Ultzex 4020L, manufactured by Prime Polymer Co., Ltd. Density 0.937 g/cm ³ , MFR 2.3 g/10 min.
- LLDPE2: Evolue SP2020, LLDPE manufactured by Prime Polymer Co., Ltd. Density 0.916 g/cm ³ , MFR 2.0 g/10 min.
- LDPE1: LDPE manufactured by Japan Polyethylene Co., Ltd., Novatec LC520. Density 0.923 g/cm ³ , MFR 3.6 g/10 min.
PP1: PP, Wintech WFW4M, manufactured by Japan Polypropylene Co., Ltd. Density 0.9 g/cm ³ , MFR 7.0 g/10 min.

[others]
Nylon film 1: Harden film NAP02 manufactured by Toyobo Co., Ltd., 25 μm thick. Nylon film 2: Harden film NAP02 manufactured by Toyobo Co., Ltd., 15 μm thick. PET film 1: Biaxially stretched PET film, E5100 manufactured by Toyobo Co., Ltd., 12 μm thick.
Aluminum foil 1: 8021 material manufactured by Toyo Aluminum Co., Ltd., 40 μm thick.
DL adhesive 1: Dry laminating adhesive, RU-004/H-1, manufactured by Rock Paint Co., Ltd.
- EC adhesive 1: Admer NF528, acid-modified polyethylene manufactured by Mitsui Chemicals, Inc.
EC adhesive 2: Mitsui Chemicals, Inc. acid-modified polypropylene, Admer QF551,

<Preparation of Masterbatch>
[Preparation of Masterbatch 1]
LDPE1 and MOF1, an outgas physical absorbent, were melt-blended in the following ratio to obtain master batch 1 (MB1).
LDPE1 90 parts by mass MOF1 10 parts by mass

[Preparation of Masterbatches 2 to 14]
According to the formulations in Tables 1 and 2, melt blending was carried out in the same manner as for Masterbatch 1 to obtain Masterbatches 2 to 14 (MB2 to 14).

[Example 1]
The following raw materials were mixed by dry blending to obtain a resin composition for an outgas absorbing layer.
MB1 50 parts by mass LLDPE1 50 parts by mass Next, nylon film 1 for the base layer and aluminum foil 1 for the gas barrier layer were bonded together by dry lamination (drying temperature 70°C) using DL adhesive 1 (coating amount 3.5 g/ ^m2 ) to produce a laminated film with the following layer structure.
Layer structure: nylon film 1 (25 μm)/DL adhesive 1 (3.5 g/m ² )/aluminum foil 1 (40 μm)
Then, the EC adhesive 1 and the resin composition for the outgas absorbing layer obtained above were co-extruded onto the aluminum foil 1 side of the laminated film obtained above, and an outgas absorbing packaging material having the following layer structure was obtained by a co-extrusion lamination method. Various evaluations were then carried out.
Layer structure: nylon film 1 (thickness 25 μm)/DL adhesive 1 (coating amount 3.5 g/m ² )/aluminum foil 1 (thickness 40 μm)/EC adhesive 1 (thickness 15 μm)/outgas absorbing layer (thickness 30 μm)

[Examples 2 to 8, 10 to 20, Comparative Examples 3 and 4]
According to the descriptions in Tables 3 to 6, a master batch was selected to prepare a resin composition for an outgas absorbing layer, and materials for each layer were selected. The same procedure as in Example 1 was carried out to obtain an outgas absorbing packaging material for a lithium ion battery, and the material was evaluated in the same manner.

[Example 9]
The following raw materials were mixed by dry blending to obtain a resin composition for an outgas absorbing layer.
MB6 25 parts by mass MB7 25 parts by mass LLDPE1 50 parts by mass Next, a PET film 1 for the base layer, a nylon film 1 for the intermediate layer, and an aluminum foil 1 for the barrier layer were bonded together by dry lamination (drying temperature 70°C) using DL adhesive 1 (coating amount between each layer: 3.5 g/ ^m2 ) to produce a laminated film of PET film 1 (12 μm)/DL adhesive 1 (3.5 g/ ^m2 )/nylon film 1 (15 μm)/DL adhesive 1 (3.5 g/ ^m2 )/aluminum foil 1 (40 μm).
Then, LDPE 1 and the resin composition for the outgas absorbing layer obtained above were co-extruded onto the aluminum foil 1 side of the laminated film obtained above, and an outgas absorbing packaging material for lithium ion batteries having the following layer structure was obtained by a co-extrusion lamination method. Various evaluations were then carried out.
Layer structure: PET film 1 (12 μm) / DL adhesive 1 (3.5 g / m2) / nylon film 1 (15 μm) / DL adhesive 1 (3.5 g / m2) / aluminum foil 1 (40 μm) / LDPE 1 (thickness 15 μm) / outgas absorbing layer (thickness 30 μm)

[Comparative Example 1]
According to the description in Table 6, the same procedure as in Example 1 was repeated, except that a heat seal layer made of LLDPE1 was formed instead of the outgas absorbing layer, to obtain a packaging material, which was similarly evaluated.

[Comparative Example 2]
According to the description in Table 6, the same procedure as in Example 1 was repeated, except that a heat seal layer made of PP1 was formed instead of the outgas absorbing layer, to obtain a packaging material, which was then similarly evaluated.

<Summary of results>
The outgassing absorbing laminates of all the examples of the present invention exhibited good manufacturability, heat sealability, and reduced outgassing concentration.
However, Comparative Examples 1 and 2, which did not contain an outgassing absorbent, showed poor effects in reducing the outgas concentration.
Comparative Examples 3 and 4, in which the gas absorbent content was too high, showed poor heat sealability, and further evaluation was discontinued.

＜Evaluation＞

[Manufacturing suitability]
The appearance of the laminate was observed with the naked eye, and the presence or absence of defects was evaluated according to the following evaluation criteria.
A: The laminate had no wrinkles, bumps, or peeling.
x: Wrinkles, bumps, or peeling were observed in the laminate.

[Heat sealability]
The laminate was cut into 10 cm x 10 cm pieces, the sealant sides were overlapped, and a 1 cm x 10 cm area was heat-sealed under the following conditions using a heat seal tester (TP-701-A manufactured by Tester Sangyo Co., Ltd.). The ends were not heat-sealed or bonded, and a test piece for peel strength was prepared in a bifurcated state.
This test piece was cut into a strip of 15 mm width, and each bifurcated end was attached to a tensile tester to measure the peel strength (N/15 mm) under the conditions described below, and the pass/fail judgment was made according to the pass/fail judgment criteria described below.
Heat sealing conditions Temperature: 160°C
Pressure: 1 kgf/ ^cm2
Time: 1 second Test conditions Test speed: 300 mm/min Load range: 50 N
Pass/fail criteria: ◯: 30N/15mm or more, passed.
×: Less than 30N/15mm, not acceptable.

[Outgassing concentration]
The laminate was cut into pieces of 20 x 20 cm and placed in a gas sampling bag (packaging material layer structure: IB-PET-PIR (thickness 12 μm)/adhesive layer/ONy (thickness 15 μm)/adhesive layer/LLDPE film (thickness 60 μm)). The gas sampling bag was filled with 1000 ml of a test mixed gas adjusted to carbon dioxide: 2%, acetaldehyde: 50 ppm, acetic acid: 30 ppm, and butane: 100 ppm, and then sealed.
After leaving the mixture at 23° C. for 48 hours, the concentrations of the following gas components were measured using the following detector tubes.
Butane concentration: detector tube (Gastec, No. 104)
Carbon dioxide concentration: (CHECK POINT II manufactured by MOCON)
Acetaldehyde concentration: detector tube (Gastec, No. 92M)
Acetic acid concentration: detector tube (Gastec, No. 81)

1 Outgas absorbing packaging material 2 Base layer 3 Intermediate layer 4 Gas barrier layer 5 Sealant layer 6 Outgas absorbing layer 7 Outgas absorbing agent 8 Heat seal layer

Claims (7)

An outgassing absorbing packaging material for a liquid electrolyte type lithium ion battery, which absorbs organic gases, carbon monoxide, and carbon dioxide, comprising:
The outgassing absorbing packaging material includes at least a base layer made of a base film, a gas barrier layer made of a gas barrier film, and a sealant layer made of an outgassing absorbing sealant film,
The outgassing absorbing sealant film contains an outgassing absorbent and a heat sealable resin,
The outgassing absorbent contains an outgassing physical absorbent, or contains an outgassing physical absorbent and an outgassing chemical absorbent;
The BET specific surface area of the outgas physical absorbent is 50 m ² /g or more and 4000 m ² /g or less,
the outgassing physical absorbent is a metal-organic framework and/or a zeolite;
The zeolite is a CHA type zeolite or an MFI type zeolite,
the outgassing chemical absorbent is _Li2O , LiCl, LiOH, BeO, or RaO;
The content of the outgas absorbent in the layer containing the outgas absorbent is 0.5% by mass or more and 30% by mass or less.
Outgassing absorbing packaging materials. The pore diameter of the gas physical absorbent is 0.1 nm or more and 2 nm or less.
2. The outgassing absorbing packaging material of claim 1. The gas physical absorbent further contains one or more selected from the group consisting of activated clay, sepiolite, and halloysite.
3. The outgassing absorbing packaging material of claim 2. The organic gas is one or more selected from the group consisting of alkanes, alkenes, aldehydes, ketones, and organic acids.
An outgassing absorbing packaging material according to any one of claims 1 to 3. The base film contains a polyamide resin and/or a polyester resin.
An outgassing absorbing packaging material according to any one of claims 1 to 4. The gas barrier film is an aluminum foil.
An outgassing absorbing packaging material according to any one of claims 1 to 5. A packaging material made from the outgassing absorbing packaging material according to any one of claims 1 to 6.
Outgassing liquid electrolyte type lithium ion battery packaging.

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