WO2023228601A1

WO2023228601A1 - Oxygen absorbing laminate

Info

Publication number: WO2023228601A1
Application number: PCT/JP2023/014314
Authority: WO
Inventors: 大樹駒形; 智弘宮井; 敬弘赤羽根; 佳織島野
Original assignee: 東洋製罐グループホールディングス株式会社
Priority date: 2022-05-27
Filing date: 2023-04-07
Publication date: 2023-11-30
Also published as: JPWO2023228601A1

Abstract

The present invention controls oxygen absorbing reaction of an oxygen absorbing resin by providing a layer containing a resin composition with an acid value of 3 mgKOH/g or more such that the layer is adjacent to an oxygen absorbing resin layer that contains an oxygen absorbing resin and a transition metal catalyst. The present invention thus enables the finite oxygen absorbing performance of the oxygen absorbing resin to be demonstrated more effectively.

Description

Oxygen absorbing laminate

The present invention relates to an oxygen-absorbing laminate.

Conventionally, in order to prevent deterioration of the contents, so-called gas exchange packaging is known, in which the air inside the package is replaced with an inert gas such as nitrogen while the contents are filled and sealed. Gas replacement involves sucking and exhausting air from the package when filling the contents, or forcibly replacing the air inside the package with inert gas, but gas replacement packaging also removes oxygen from the package. It is difficult to completely remove it. For this reason, the present applicant has proposed a packaging film having an oxygen absorption function, for example in Patent Document 1.

Japanese Patent Application Publication No. 2001-039475

By using a packaging film with such an oxygen-absorbing function to remove oxygen remaining inside the package after filling, it is possible to prevent deterioration of the packaged object due to oxidation and enable long-term storage. can do.

However, the oxygen-absorbing resin responsible for the oxygen-absorbing performance in the above-mentioned background art starts reacting with oxygen when exposed to air, so it cannot be used in the film manufacturing process, bag-making process, or packaging process for packaging objects. If the oxygen absorption reaction progresses, there is a risk that the oxygen absorption performance will be reduced upon completion of packaging.

Therefore, the inventors of the present invention have conducted intensive studies to control the oxygen absorption reaction until the packaging is completed to more effectively utilize the limited oxygen absorption performance of the oxygen-absorbing resin. The invention was completed.

The oxygen-absorbing laminate according to the present invention is an oxygen-absorbing laminate having at least an oxygen-absorbing resin layer containing an oxygen-absorbing resin and a transition metal catalyst, and an adjacent layer adjacent to the oxygen-absorbing resin layer. The adjacent layer contains a resin composition having an acid value of 3 mgKOH/g or more.

According to the present invention, the catalytic activity of the transition metal catalyst contained in the oxygen-absorbing resin layer can be suppressed to control the oxygen absorption reaction of the oxygen-absorbing resin.

Hereinafter, the oxygen-absorbing laminate according to the present invention will be described while showing embodiments thereof.

The oxygen-absorbing laminate according to the present embodiment is a laminate having at least an oxygen-absorbing resin layer containing an oxygen-absorbing resin and a transition metal catalyst, and an adjacent layer adjacent to the oxygen-absorbing resin layer. Such an oxygen-absorbing laminate is suitable for use as a packaging film having an oxygen-absorbing function, and arbitrary layers can be appropriately selected and laminated so as to be more suitable for such use. For example, when applied to a packaging film, there is a surface-side base material layer that is located on the front side and forms a surface layer, and an inside-side base material layer that is located on the inside side and forms an inner layer that is in contact with the contents. Material layers etc. can be laminated. As an example of an oxygen-absorbing laminate, a preferred embodiment will be described below in which the layer structure is a front-side base material layer/adjacent layer/oxygen-absorbing resin layer/inner-side base material layer.

[Oxygen-absorbing resin layer]
The oxygen-absorbing resin layer contains an oxygen-absorbing resin as a main component, and also contains a transition metal catalyst for the main purpose of promoting the oxygen-absorbing reaction of the oxygen-absorbing resin.

Examples of transition metal catalysts include transition metals such as manganese, iron, cobalt, nickel, copper, silver, tin, titanium, vanadium, chromium, and zirconium, particularly preferably transition metals such as manganese, iron, cobalt, nickel, and copper. Examples include inorganic salts, organic salts, and complex salts. More specifically, the transition metal catalyst includes a transition metal salt consisting of a transition metal selected from manganese, iron, cobalt, nickel, and copper and an organic acid. In particular, from the viewpoint of accelerating the oxygen absorption reaction of the oxygen-absorbing resin and increasing the oxygen absorption property, the transition metal catalyst is preferably an organic acid salt of manganese, iron, or cobalt, and particularly preferably an organic acid salt of cobalt. The content of the transition metal catalyst in the oxygen-absorbing resin layer is preferably 1 ppm to 1000 ppm, more preferably 10 ppm to 500 ppm, still more preferably 20 ppm to 300 ppm, in terms of metal.

As the oxygen-absorbing resin, it is preferable to use an oxygen-absorbing polyester resin whose structure includes a functional group or a bonding group that is reactive with oxygen. Examples of the functional group or bonding group having reactivity with oxygen include a carbon-carbon double bond group, an aldehyde group, and a phenolic hydroxyl group. In particular, unsaturated polyester resins having a carbon-carbon double bond group are preferred, and polyester resins having an unsaturated alicyclic structure are more preferred. A polyester resin having an unsaturated alicyclic structure is advantageous because the amount of low molecular weight decomposed components that are by-products in the autooxidation reaction of the resin is suppressed.

Examples of polyester resins having an unsaturated alicyclic structure include polyesters obtained by using tetrahydrophthalic acid or its derivatives or tetrahydrophthalic anhydride or its derivatives as an acid component and polymerizing them with a diol component. When using tetrahydrophthalic acid or its derivatives or tetrahydrophthalic anhydride or its derivatives as the acid component, these may be esterified to methyl ester or the like.

Tetrahydrophthalic acid or its derivatives or tetrahydrophthalic anhydride or its derivatives include 4-methyl-Δ ³ -tetrahydrophthalic acid or 4-methyl- ^{Δ 3} -tetrahydrophthalic anhydride, cis-3-methyl-Δ ⁴ -tetrahydro Particularly preferred is phthalic acid or cis-3-methyl-Δ ⁴ -tetrahydrophthalic anhydride. These tetrahydrophthalic acid or its derivatives or tetrahydrophthalic anhydride or its derivatives have very high reactivity with oxygen and can therefore be suitably used as the acid component.

Note that these tetrahydrophthalic acid or its derivatives or tetrahydrophthalic anhydride or its derivatives are 4-methyl-Δ ⁴ - which is obtained by reacting a C5 fraction of naphtha containing isoprene and trans-piperylene as main components with maleic anhydride. It can be obtained by structural isomerizing an isomer mixture containing tetrahydrophthalic anhydride, and is produced industrially.

Examples of diol components include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, and 3-methyl. -1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 2- Phenylpropanediol, 2-(4-hydroxyphenyl)ethyl alcohol, α,α-dihydroxy-1,3-diisopropylbenzene, o-xylene glycol, m-xylene glycol, p-xylene glycol, α,α-dihydroxy-1 , 4-diisopropylbenzene, hydroquinone, 4,4-dihydroxydiphenyl, naphthalene diol, or derivatives thereof. Preferred are aliphatic diols, such as diethylene glycol, triethylene glycol, 1,4-butanediol, and more preferred is 1,4-butanediol. When 1,4-butanediol is used, an oxygen-absorbing polyester resin with high oxygen-absorbing performance and a small amount of decomposed products produced during the oxidation process can be obtained. These diol components can be used alone or in combination of two or more.

In addition to tetrahydrophthalic acid or its derivatives or tetrahydrophthalic anhydride or its derivatives, the oxygen-absorbing polyester resin may contain other acid components such as aromatic dicarboxylic acids, aliphatic dicarboxylic acids, aliphatic hydroxycarboxylic acids, or derivatives thereof. It may be copolymerized by including it in the raw material monomer.

Aromatic dicarboxylic acids and their derivatives include phthalic acid, phthalic anhydride, isophthalic acid, benzene dicarboxylic acids such as terephthalic acid, naphthalene dicarboxylic acids such as 2,6-naphthalene dicarboxylic acid, anthracene dicarboxylic acid, sulfoisophthalic acid, and sulfonate dicarboxylic acids. Examples include sodium isophthalate and derivatives thereof. Among these, phthalic acid, phthalic anhydride, isophthalic acid, and terephthalic acid are preferred.

Aliphatic dicarboxylic acids and their derivatives include oxalic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, 3 , 3-dimethylpentanedioic acid, or derivatives thereof. Among these, succinic acid, succinic anhydride, adipic acid, and sebacic acid are preferred, and succinic acid is particularly preferred. Examples include hexahydrophthalic acid having an alicyclic structure, dimer acid, and derivatives thereof.

Examples of aliphatic hydroxycarboxylic acids and derivatives thereof include glycolic acid, lactic acid, hydroxypivalic acid, hydroxycaproic acid, hydroxyhexanoic acid, and derivatives thereof.

These other acid components may be esterified, such as dimethyl terephthalate and bis-2-hydroxydiethyl terephthalate, or may be acid anhydrides, such as phthalic anhydride and succinic anhydride. . These other acid components can be used alone or in combination of two or more.

By copolymerizing other acid components, the glass transition temperature of the resulting oxygen-absorbing polyester resin can be easily controlled, and the oxygen-absorbing performance can be improved. Furthermore, the solubility in organic solvents can be improved by controlling the crystallinity of the oxygen-absorbing polyester resin.

In addition, since tetrahydrophthalic acid or its derivatives or tetrahydrophthalic anhydride or its derivatives are susceptible to radical crosslinking reactions due to heat during polymerization, other acid components may be blended to remove tetrahydrophthalic acid or its derivatives contained in the raw material monomers. By reducing the composition ratio of its derivative or tetrahydrophthalic anhydride or its derivative, gelation during polymerization can be suppressed and a high molecular weight oxygen-absorbing polyester resin can be stably obtained.

The oxygen-absorbing polyester resin may further contain a structural unit derived from a polyhydric alcohol, a polycarboxylic acid, a derivative thereof, or the like. By controlling the branched structure by introducing a polyhydric alcohol and a polyhydric carboxylic acid, the melt viscosity characteristics and the solution viscosity characteristics of the polyester dissolved in the solvent can be adjusted.

Polyhydric alcohols and their derivatives include 1,2,3-propanetriol, sorbitol, 1,3,5-pentanetriol, 1,5,8-heptanetriol, trimethylolpropane, pentaerythritol, 3,5-dihydroxy Examples include benzyl alcohol, glycerin, and derivatives thereof.
Examples of polycarboxylic acids and derivatives thereof include 1,2,3-propanetricarboxylic acid, meso-butane-1,2,3,4-tetracarboxylic acid, citric acid, trimellitic acid, pyromellitic acid, or these. Examples include derivatives.
Further, when copolymerizing a component having a trifunctional or higher functional group such as a polyhydric alcohol or a polycarboxylic acid, the amount is preferably within 5 mol % based on the total acid component.

In this embodiment, the oxygen-absorbing resin includes tetrahydrophthalic acid or its derivatives or tetrahydrophthalic anhydride or its derivatives as an acid component, 1,4-butanediol as a diol component, and succinic acid or succinic anhydride as an acid component. It is preferable to use an oxygen-absorbing polyester resin obtained by copolymerizing these as the acid component.

In this case, the structural unit derived from tetrahydrophthalic acid or its derivative or tetrahydrophthalic anhydride or its derivative contained in the oxygen-absorbing polyester resin preferably accounts for 70 to 95 mol% of the total acid component. , more preferably 75 to 95 mol%, still more preferably 80 to 95 mol%.
Further, the structural unit derived from succinic acid or succinic anhydride preferably accounts for 0 to 15 mol%, more preferably 0 to 12.5 mol%, and even more preferably 0 to 12.5 mol% of the total acid components. It is 10 mol%.
By using such a composition ratio, it is possible to obtain an oxygen-absorbing resin that has excellent oxygen-absorbing performance and adhesive properties, and also has excellent solubility in organic solvents.

The oxygen-absorbing polyester resin can be synthesized, for example, by interfacial polycondensation, solution polycondensation, melt polycondensation, or solid phase polycondensation. At this time, a polymerization catalyst is not necessarily required, but a typical polyester polymerization catalyst such as titanium-based, germanium-based, antimony-based, tin-based, or aluminum-based catalyst can be used. Known polymerization catalysts such as nitrogen-containing basic compounds, boric acid and boric acid esters, and organic sulfonic acid compounds can also be used. Furthermore, during polymerization, various additives such as coloring inhibitors such as phosphorus compounds and antioxidants may be added. By adding an antioxidant, it is possible to suppress oxygen absorption during polymerization and subsequent processing, thereby suppressing performance deterioration and gelation of the oxygen-absorbing resin.

In addition, during polymerization, the raw material monomers are adjusted so that the melt viscosity at a shear rate of 100 s ^-1 at a temperature of 220° C. is less than 90 Pa.s, preferably less than 60 Pa.s, and more preferably less than 30 Pa.s. It is preferable to adjust polymerization conditions such as composition ratio and molecular weight as appropriate. By keeping the melt viscosity low, it is possible to exhibit good coating properties, and by adding a hardening agent, it is possible to achieve desired material strength, making it suitable as a solvent-soluble dry laminating adhesive. It can be suitably used.

The number average molecular weight of the oxygen-absorbing polyester resin is preferably 500 to 100,000, more preferably 2,000 to 10,000. Further, the weight average molecular weight is preferably 5,000 to 200,000, more preferably 10,000 to 100,000, and still more preferably 20,000 to 70,000. If the molecular weight is lower than the above range, the cohesive force or creep resistance of the resin will decrease, and if it is higher, the solubility in organic solvents will decrease and the coatability will decrease due to an increase in solution viscosity, which is not preferred.
The glass transition temperature of the oxygen-absorbing polyester resin is preferably -20°C to 10°C, more preferably -15°C to 6°C, and even more preferably -12°C to 2°C. By setting the glass transition temperature within such a range, sufficient oxygen absorption performance can be obtained.
The acid value of the oxygen-absorbing polyester resin is preferably less than 3 mgKOH/g, more preferably less than 1 mgKOH/g, in order to obtain sufficient oxygen absorption performance. If the acid value exceeds 3 mgKOH/g, rapid autooxidation reaction may be hindered and stable oxygen absorption performance may not be obtained.
Note that the method for measuring the acid value of the oxygen-absorbing polyester resin is based on JIS K 0070.

Additionally, the laminate strength of oxygen-absorbing polyester resins may decrease due to internal stress generated along with oxygen-absorbing reactions (oxidative hardening reactions). In order to suppress this, it is preferable to blend a component with a low glass transition temperature that is mainly composed of a saturated polyester resin. Such a component can relieve the internal stress generated due to the oxidative hardening reaction due to its flexibility.

The saturated polyester resin is a polyester resin that does not substantially contain carbon-carbon double bond groups, and can be obtained, for example, by polycondensation of a dicarboxylic acid component, a diol component, or a hydroxycarboxylic acid component. The saturated polyester resin is preferably a polyester having an iodine value of 3 g/100 g or less, particularly a polyester having an iodine value of 1 g/100 g or less. When the iodine value of the saturated polyester resin exceeds 3 g/100 g, it is not preferable because low molecular weight decomposed components are likely to be generated due to the oxygen absorption reaction of the oxygen absorbing resin.
Note that the method for measuring the iodine value is based on JIS K 0070.

Examples of the dicarboxylic acid component include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, hexahydrophthalic acid, dimer acids, and derivatives thereof, which are exemplified as components of the oxygen-absorbing polyester resin described above. These can be used alone or in combination of two or more.
Examples of the diol component include the diols exemplified as components of the oxygen-absorbing polyester resin described above. These can be used alone or in combination of two or more.
Examples of the hydroxycarboxylic acid component include the aliphatic hydroxycarboxylic acids exemplified as components of the oxygen-absorbing polyester resin described above.

The glass transition temperature of the saturated polyester resin is preferably -10°C or lower, more preferably -70°C to -15°C, and even more preferably -60°C to -20°C. By setting the glass transition temperature within such a range, internal stress caused by oxidative hardening reaction due to oxygen absorption can be effectively alleviated.

The ratio A/B of the oxygen-absorbing polyester resin (A) and the saturated polyester resin (B) is preferably 0.6 to 9, more preferably 1 to 9, and still more preferably 2 to 9. . By setting the ratio A/B within such a range, it is possible to exhibit excellent oxygen absorption performance and maintain strong laminate strength before and after oxygen absorption.

Furthermore, in forming the oxygen-absorbing resin layer, the oxygen-absorbing resin can be prepared by dissolving it in an organic solvent so that it can be used as an oxygen-absorbing adhesive. Examples of the organic solvent include ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, and isopropanol. In particular, ethyl acetate is commonly used as a solvent for dry laminating adhesives for flexible packaging because it has relatively few odor problems caused by residual solvents, and when considering industrial applications, ethyl acetate, which does not contain toluene or xylene, is used. Preferably, one solvent is used.

When using an oxygen-absorbing polyester resin, it can be used as a two-component curing adhesive by blending an isocyanate curing agent with it. When an isocyanate-based curing agent is blended, adhesive strength and cohesive force are increased, and curing can be performed at a low temperature around room temperature.
Examples of the isocyanate curing agent include aliphatic isocyanates such as xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), lysine diisocyanate, lysine methyl ester diisocyanate, trimethylhexamethylene diisocyanate, and n-pentane-1,4-diisocyanate. Examples include alicyclic isocyanate-based curing agents such as isophorone diisocyanate (IPDI), cyclohexane-1,4-diisocyanate, methylcyclohexyl diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate. Among these, XDI and HDI are preferable as the aliphatic isocyanate curing agent, and IPDI is preferable as the alicyclic isocyanate curing agent. Particularly preferred is XDI. By using XDI, the most excellent oxygen absorption performance is exhibited.
These aliphatic and/or alicyclic isocyanate curing agents are preferably used as polyisocyanate compounds with increased molecular weight, such as adducts, isocyanurates, and burettes.
Further, these aliphatic and/or alicyclic isocyanate curing agents may be used alone or in combination of two or more.

The isocyanate curing agent is preferably added in an amount of 3 phr to 30 phr, more preferably 3 phr to 20 phr, still more preferably 3 phr to 15 phr, based on the solid weight part, relative to the oxygen-absorbing polyester resin that is the main ingredient. If the amount added is too small, the adhesion and cohesive force will be insufficient, and if it is too large, the amount of the oxygen absorbing component contained in the unit weight of the resin composition will be small, resulting in insufficient oxygen absorption performance. Furthermore, if the mobility of the resin is significantly reduced due to curing, the oxygen absorption reaction will be difficult to proceed and the oxygen absorption performance will be reduced.

[Adjacent layer]
The adjacent layer contains a resin composition with an acid value of 3 mgKOH/g or more, preferably an acid value of 4 mgKOH/g or more, more preferably an acid value of 5 mgKOH/g or more, and a transition metal that promotes the oxygen absorption reaction of the oxygen-absorbing resin. The layer is laminated adjacent to the oxygen-absorbing resin layer in order to trap the catalyst through coordination bonds or the like, suppress its catalytic activity, and control the oxygen-absorbing reaction of the oxygen-absorbing resin.
Note that the method for measuring the acid value is based on JIS K 0070.

In this embodiment, as the resin composition to be contained in the adjacent layer, any resin composition that has an acidic group such as a carboxyl group in the side chain or at the end and has an acid value equal to or higher than the above-mentioned value can be used. However, such a resin composition preferably contains a polyurethane resin. More specifically, polyurethane resins produced by condensation reaction of polyol and polyisocyanate, or polyurethane polymers having terminal isocyanate groups, which are condensation reaction products of polyol and polyisocyanate, are produced by reaction with polyamines. It is preferable that the polyurethane resin (polyurethane urea resin) is contained. In particular, it is preferable to include a polyurethane resin in which a carboxyl group is introduced into the side chain or terminal. The compound used to introduce a carboxyl group may be a compound that reacts with an isocyanate group and has a free carboxyl group, such as a hydroxycarboxylic acid or an aminocarboxylic acid, or a compound that reacts with an isocyanate group, or a compound that reacts with an isocyanate group, or a compound that reacts with an isocyanate group and that has a free carboxyl group, or a compound that reacts with an isocyanate group, and a compound that reacts with an isocyanate group, such as a hydroxycarboxylic acid or an aminocarboxylic acid that has a free carboxyl group, or a compound that reacts with an isocyanate group. A cyclic dicarboxylic acid anhydride that forms a carboxyl group can be used.

As the polyol, for example, a polyester polyol obtained by esterifying a dibasic acid and a diol can be used. Examples of dibasic acids include oxalic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic anhydride, and isophthalic acid. acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid, dimer acid, hydrogenated dimer acid, and the like. These can be used alone or in combination of two or more.

Examples of diols include ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1, Linear diols such as 9-nonanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl- 1,3-propanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, pentylene glycol, 1,2-propylene glycol, 2,4-diethyl-1,5-pentanediol, 1,3- Branched diols such as butanediol and dipropylene glycol are mentioned. These can be used alone or in combination of two or more.

Examples of polyisocyanates include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzylisocyanate, dialkyldiphenylmethane diisocyanate, and tetraalkyl diisocyanate. Diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, 1,5-pentamethylene diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2, 2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1, Examples include 3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimer diisocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group. These can be used alone or in combination of two or more.

Examples of polyamines include ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, Di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, diethylenetriamine, iminobispropylamine: (IBPA, 3,3'-diaminodipropylamine), N-(3-aminopropyl)butane-1,4-diamine: (spermidine), 6,6-iminodihexylamine, 3,7-diazanonane-1,9-diamine , N,N'-bis(3-aminopropyl)ethylenediamine, and the like. These can be used alone or in combination of two or more.

In addition, in the above raw material components, dibasic acids such as sebacic acid, succinic acid, dimer acid, ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, pentyl glycol, etc. Diols such as lene glycol, diisocyanates such as 1,5-pentamethylene diisocyanate, and dimer diisocyanate are available as biomass-derived raw materials, and by copolymerizing polyurethane resin using these biomass-derived raw material components, Its biomass degree can be increased.

The adjacent layer can be formed, for example, by a printing ink prepared using the above resin composition as a binder resin. In this case, in order to have good printability and blocking resistance, resins other than polyurethane resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, cellulose resin, rosin resin, etc. It is preferable to prepare a binder resin by appropriately combining one or more types of components, and among these, it is particularly preferable to use a vinyl chloride-vinyl acetate copolymer resin.
Note that even when resin components other than polyurethane resin are used in combination, the acid value of the resin composition used for the binder resin should be adjusted to be equal to or higher than the above-mentioned value. When laminating the adjacent layer adjacent to the oxygen-absorbing resin layer, the thickness of the adjacent layer is preferably 0.1 to 10 μm, more preferably 0.2 to 5 μm, and even more preferably 0.3 to 3 μm. It is.

Furthermore, the printing ink forming the adjacent layer may be prepared as a medium containing no pigment, or may be prepared as a colored ink containing an inorganic pigment or an organic pigment. However, some inorganic pigments such as titanium oxide, which is generally known as a white pigment, function as catalysts that promote the oxygen absorption reaction of oxygen-absorbing resins, and such pigments may If it is contained in the above, it is not preferable because it impairs the effect of the present invention.

Furthermore, examples of organic solvents for preparing printing inks include ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, isopropanol, and the like.

[Surface side base material layer]
For the surface side base material layer, from the viewpoint of scratch resistance and chemical resistance, for example, a biaxially stretched film made of polyester resin such as polyethylene terephthalate, polyamide resin such as nylon, etc. is used as the base film, and polyvinyl Coating layers based on oxygen barrier resins such as alcohol-based resins, ethylene-vinyl alcohol copolymers, polyacrylic acid-based resins, and vinylidene chloride-based resins, metal oxides such as silica and alumina, or vapor-deposited thin films of metals, etc. Although it is preferable to use a laminated film including a laminated film, a laminated film formed by dry laminating a metal foil such as an aluminum foil on the base film with a urethane adhesive or the like interposed therebetween, the present invention is not limited thereto.

[Inner side base material layer]
The inner side base material layer may be a single layer or a laminate. Examples of the base resin include polyolefin resins and polyester resins. Among these, polyolefin resins include low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), linear very low density polyethylene (LVLDPE), and polypropylene. (PP), ethylene-propylene copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene-vinyl acetate copolymer A combination, an ionically crosslinked olefin copolymer (ionomer), or a blend thereof is preferred. In particular, when used in a heat-sealing layer of a packaging film, LDPE and LLDPE, which have excellent heat-sealability, are particularly preferred. As the polyester resin, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), copolyesters thereof, or blends thereof are preferable. Moreover, polyester resin modified with isophthalic acid is preferable because it has low crystallinity and can be heat-sealed.

In this embodiment as described above, the oxygen-absorbing resin layer containing an oxygen-absorbing resin and a transition metal catalyst that promotes the oxygen-absorbing reaction has an acid value of 3 mgKOH/g or more (preferably the above-mentioned value). By placing the layers containing the resin compositions (above) adjacent to each other, the transition metal catalyst can be captured by coordination bonds or the like, and the catalytic activity can be suppressed. This reduces the amount of oxygen absorbed by the oxygen-absorbing resin at the initial stage of exposure to air and the start of the oxygen absorption reaction, thereby reducing the influence of air exposure and improving handling properties. It is possible to control the oxygen absorption reaction of the oxygen-absorbing resin so that the rate at which the oxygen absorption amount of the oxygen-absorbing resin decreases decreases over time. It becomes possible to exhibit absorption performance more effectively.

Hereinafter, the present invention will be explained in more detail with reference to specific examples.

[Example 1]
As the acid component, a methyltetrahydrophthalic anhydride isomer mixture (manufactured by Hitachi Chemical Co., Ltd.; HN-2200) was used at a molar ratio of 0.9, as the other acid component was succinic anhydride at a molar ratio of 0.1, and as the diol component was a 1,4- A reaction vessel was charged with butanediol at a molar ratio of 1.3 and isopropyl titanate as a polymerization catalyst at a composition ratio of 300 ppm, and the mixture was reacted for about 6 hours in a nitrogen atmosphere while removing generated water at 150° C. to 200° C. Subsequently, polymerization was performed at 200 to 220° C. for about 3 hours under a reduced pressure of 0.1 kPa to obtain an oxygen-absorbing polyester resin (A). The oxygen-absorbing polyester resin (A) had a number average molecular weight (Mn) of 4,800, a weight average molecular weight (Mw) of 57,200, and a glass transition point (Tg) of -5.0°C.

To the obtained oxygen-absorbing polyester resin (A), a saturated polyester resin (B) (manufactured by DIC Corporation; Polysizer W4010/Mn: 3600, Mw: 9500) with a Tg of -26°C was added to the solid content weight ratio A/B of 4. HDI/IPDI curing agent (DIC Graphics Co., Ltd.) KL-75) was mixed. Further, as a catalyst, cobalt neodecanoate was added in an amount of 80 ppm in terms of metal based on the total solid content, and dissolved in ethyl acetate to prepare an oxygen-absorbing adhesive solution with a solid content concentration of 20 wt%.

A resin composition containing a polyurethane resin prepared by copolymerizing raw materials containing neopentyl glycol, adipic acid, and isophorone diisocyanate and having an acid value of 7.5 mgKOH/g was diluted with ethyl acetate and transparently vapor-deposited using a bar coater. It was applied to the barrier coating surface of a nylon film (manufactured by Toppan Printing Co., Ltd.; GL-EY/film thickness 15 μm), and the solvent was evaporated with hot air from a hair dryer to form a 1 μm thick resin layer as an adjacent layer.

Next, an oxygen-absorbing adhesive solution is applied to the adjacent layer using a #15 bar coater, and the solvent is evaporated with hot air from a hair dryer. The resulting laminate was passed through a hot roll at 50°C with the corona-treated surfaces facing each other (40 μm) and cured for 5 days at 35°C under a nitrogen atmosphere to form a surface-side base material layer (transparent vapor-deposited nylon film: film). An oxygen-absorbing laminate consisting of an adjacent layer (thickness: 15 μm)/an oxygen-absorbing resin layer (thickness: 4 μm)/inner side base material layer (LDPE film: thickness: 40 μm) was obtained.

The oxygen absorbing performance of the oxygen absorbing laminate thus obtained was evaluated. The results are shown in Table 1.
Note that the oxygen absorption performance was evaluated as follows.
<Oxygen absorption performance>
A test piece of the oxygen-absorbing laminate cut out to 2 cm x 15 cm was placed in an oxygen-impermeable steel foil laminated cup with an internal volume of 85 cm ³ , heat-sealed and sealed with an aluminum foil laminated film lid, and heated at 22°C - 90%. It was stored under RH atmosphere. Thereafter, the oxygen concentration in the cup was measured using a micro gas chromatograph (Shimadzu Corporation: GC-2014AT) after 6 hours (6 hours) and 24 hours (24 hours). The amount of oxygen absorbed per 1 cm ² of the laminate was calculated.
<Evaluation criteria>
An oxygen-absorbing laminate having the same layer structure as above except for not having an adjacent layer was prepared, and the amount of oxygen absorbed per 1 cm ² was calculated in the same manner as above, and this was taken as 100%. The ratio of the amount of oxygen absorbed in the 6-hour period and the 24-hour period (i.e., the percentage of the amount of oxygen absorption reduced by the adjacent layer) in the oxygen-absorbing laminate of the example is determined, and the 6-hour period is less than 85%, and If the 24-hour period is 85% or more, it is indicated as "〇" in Table 1, indicating that a good catalyst activity suppressing function is exhibited, and otherwise, it is indicated as "x" in Table 1, indicating that the catalyst activity suppressing function is not exhibited. Indicated.

[Example 2]
A resin composition containing a polyurethane resin formed by copolymerizing raw materials containing 3-methyl-1,5-pentanediol, adipic acid, and isophorone diisocyanate and having an acid value of 5.3 mgKOH/g is used to An oxygen-absorbing laminate was obtained in the same manner as in Example 1 except that the layers were formed. The oxygen absorbing performance of the obtained oxygen absorbing laminate was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

[Example 3]
A resin composition containing a polyurethane resin formed by copolymerizing raw materials containing 3-methyl-1,5-pentanediol, adipic acid, sebacic acid, and isophorone diisocyanate and adjusted to an acid value of 5.4 mgKOH/g is used. An oxygen-absorbing laminate was obtained in the same manner as in Example 1, except that the adjacent layer was formed. The oxygen absorbing performance of the obtained oxygen absorbing laminate was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

[Example 4]
Except that the adjacent layer was formed using a resin composition containing a polyurethane resin formed by copolymerizing raw material components containing ethylene glycol, adipic acid, and isophorone diisocyanate and having an acid value of 4.2 mgKOH/g. An oxygen-absorbing laminate was obtained in the same manner as in Example 1. The oxygen absorbing performance of the obtained oxygen absorbing laminate was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

[Example 5]
An oxygen-absorbing laminate was obtained in the same manner as in Example 1, except that 40% by weight of carbon black was added when preparing the resin composition. The oxygen absorbing performance of the obtained oxygen absorbing laminate was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

[Comparative example 1]
A resin composition containing a polyurethane resin formed by copolymerizing raw materials containing 3-methyl-1,5-pentanediol, adipic acid, and isophorone diisocyanate and having an acid value of 0.6 mgKOH/g is used to An oxygen-absorbing laminate was obtained in the same manner as in Example 1 except that the layers were formed. The oxygen absorbing performance of the obtained oxygen absorbing laminate was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

[Comparative example 2]
An oxygen-absorbing laminate was obtained in the same manner as in Example 1, except that cobalt neodecanoate as a catalyst was not added when preparing the oxygen-absorbing adhesive solution. The oxygen absorbing performance of the obtained oxygen absorbing laminate was evaluated in the same manner as in Example 1. The results are also shown in Table 1.

From these results, it can be confirmed that the amount of oxygen absorbed decreases at the beginning of the oxygen absorption reaction after exposure to air, and that the rate of decrease decreases as time passes (Examples 1 to 3). (see 5). Furthermore, if the acid value of the resin composition contained in the adjacent layer is small, the oxygen absorption amount will not be reduced (see Comparative Example 1), and even if the acid value of the resin composition contained in the adjacent layer is increased, the oxygen absorption It can be confirmed that the amount of oxygen absorption does not decrease if the resin layer does not contain a transition metal catalyst (see Comparative Example 2). Therefore, by considering these results, it can be understood that according to the present invention, the catalytic activity of the transition metal catalyst can be suppressed, and thereby the oxygen absorption reaction can be controlled.

Although the present invention has been described above by showing preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and that various modifications can be made within the scope of the present invention. .

Claims

An oxygen-absorbing laminate comprising at least an oxygen-absorbing resin layer containing an oxygen-absorbing resin and a transition metal catalyst, and an adjacent layer adjacent to the oxygen-absorbing resin layer,
An oxygen-absorbing laminate characterized in that the adjacent layer contains a resin composition having an acid value of 3 mgKOH/g or more.
The oxygen-absorbing laminate according to claim 1, wherein the resin composition contains a polyurethane resin.
The oxygen-absorbing laminate according to claim 1, wherein the resin composition contains a polyurethane resin and a vinyl chloride-vinyl acetate copolymer resin.
The oxygen-absorbing laminate according to any one of claims 1 to 3, wherein the adjacent layer is formed by a printing ink using the resin composition as a binder resin.