JP2016049780A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film which can express excellent gas barrier properties and good adhesiveness without causing delamination not only in a normal state but also after performing retort treatment, when used as the laminated film having an inorganic thin film layer and gas barrier properties, and which is produced easily and is excellent also in cost effectiveness.SOLUTION: The laminated film has a coating layer on at least one surface of a plastic base material film. The coating layer is obtained from a resin composition for the coating layer, which composition contains such an urethane resin that 50 mol% or more of a polyisocyanate component is constituted by a (hydrogenated) meta xylylene diisocyanate component and another resin having an oxazoline group as constituent components. In a total-reflection infrared absorption spectrum of the coating layer, a ratio (P1/P2) of the peak intensity (P1) of a peak having absorption maximum in a region of 1655±10 cmto that (P2) of another peak having absorption maximum in another region of 1530±10 cmsatisfies the relationship shown by the inequality:1.2≤(P1/P2)≤4.5. The amount of the coating layer to be stuck is set within a range of 0.05-0.2 g/m.SELECTED DRAWING: None

Description

  The present invention relates to a laminated film used in the field of packaging foods, pharmaceuticals, industrial products and the like. Specifically, when a gas barrier laminate film having an inorganic thin film layer is formed, the interlayer adhesion of the inorganic thin film layer can be improved, and good gas barrier properties and adhesion (laminate strength) are exhibited even after retorting. It is related with the laminated film which can be made.

  Packaging materials used for foods, pharmaceuticals, etc. should have the property of blocking gases such as oxygen and water vapor, that is, gas barrier properties, in order to prevent protein and fat oxidation, maintain taste and freshness, and maintain the efficacy of pharmaceuticals. It has been demanded. Further, gas barrier materials used for electronic devices such as solar cells and organic EL, electronic components, and the like require higher gas barrier properties than packaging materials such as food.

  Conventionally, in food applications that require blocking of various gases such as water vapor and oxygen, the surface of the base film made of plastic is made of a metal thin film made of aluminum or the like, or an inorganic oxide such as silicon oxide or aluminum oxide. A gas barrier laminate in which an inorganic thin film is formed is generally used. Among them, those formed with inorganic oxide thin films (inorganic thin film layers) such as silicon oxide, aluminum oxide, and mixtures thereof are widely used because they are transparent and the contents can be confirmed.

  However, since the above gas barrier laminate tends to be locally high in the forming process, the base material is damaged, or the low molecular weight portion or the additive portion such as a plasticizer is decomposed or degassed. As a result, defects, pinholes and the like are generated in the inorganic thin film layer, and the gas barrier property may be lowered. Furthermore, the inorganic thin film layer is cracked and cracked during post-processing of packaging materials such as printing, laminating, bag making and the like, and there is a problem that gas barrier properties are lowered. In particular, in applications where retort processing is applied to food packaging materials, etc., the gas barrier property is greatly reduced by retort processing, or the interlayer adhesion between the inorganic thin film and the resin in contact with it decreases, and the contents leak out. There was a problem.

  On the other hand, as a method for improving the deterioration of the gas barrier laminate formed with the inorganic thin film, various aqueous polyurethane resins, polyester resins, or between the polyester base film and the inorganic thin film layer formed by, for example, vapor deposition A method of providing a coating layer made of a mixture of polyurethane and polyester has been proposed (for example, Patent Document 1). Furthermore, in order to improve the water resistance of the coating layer under wet heat, it has been reported to provide a coating layer composed of various aqueous polyurethane and / or aqueous polyester resins and a water-soluble polymer containing an oxazoline group (for example, Patent Documents). 2). Providing the coating layer between the base film and the inorganic thin film can be carried out continuously during the film formation of the base material, and a greater cost reduction can be expected than when a protective layer is formed on the inorganic thin film. However, in the case of the above configuration, the coating layer itself has no gas barrier property, and the contribution to the gas barrier property is largely due to only the inorganic thin film layer. Therefore, the gas barrier property is higher than that in the case of forming the gas barrier protective layer on the inorganic thin film layer. There was not enough problem.

  Any of the above-mentioned methods is excellent in production stability and economical efficiency at the time of manufacture, and can provide a sufficiently satisfactory gas barrier property and laminate strength even when subjected to severe treatment such as retort treatment. At present, no film has been obtained.

  On the other hand, the present applicant has filed a patent application for a laminated film for vapor deposition having a polyurethane resin having a urethane bond, a urea bond, an acid group, and a resin containing an oxazoline group as a coating layer (Patent Document 3). In addition, the applicant of the present application has found a laminated film having improved laminate strength by associating the ratio of the polyurethane resin and the resin containing an oxazoline group and the thickness of the coating layer, and has already filed a patent application regarding this (Patent Document) 4).

JP-A-2-50837 JP 2002-301787 A JP 2012-206327 A JP 2012-214035 A

  In the above-mentioned Patent Document 3, the laminate strength has not been studied since it particularly aimed at improving the water vapor barrier property. Further, in Patent Document 4, oxygen permeability, water vapor permeability, and laminate strength were examined and showed good values, respectively, but there was room for improvement in gas barrier properties after retorting.

  The present invention has been made against the background of the problems of the prior art. When a gas barrier laminate film having an inorganic thin film layer is used, the gas barrier is not only normal but also after retorting. An object of the present invention is to provide a laminated film that is excellent in properties, can exhibit good adhesion without causing delamination, and is easy to manufacture and economical.

  The present inventors relate to a coating layer provided between a plastic substrate film and an inorganic thin film layer. In addition to providing gas barrier properties to the coating layer itself, the surface of the coating layer is made hydrophilic to make the inorganic thin film layer uniform and dense. It has been found that further gas barrier property improvement effect can be expected by depositing on the surface. Furthermore, the present inventors have found that the effect of improving gas barrier properties can be maintained even after retorting by causing the hydrophilic component, oxazoline group and inorganic substance in the coating layer to undergo a crosslinking reaction in a timely manner, thereby completing the present invention.

That is, the present invention has the following configuration.
(1) A coating layer is provided on at least one surface of the plastic substrate film, and the coating layer is composed of 50% by mole or more of the total polyisocyanate component with metaxylylene diisocyanate and / or hydrogenated metaxylylene diisocyanate component. Obtained from a resin composition for a coating layer comprising a urethane resin and a resin having an oxazoline group as constituent components,
In the total reflection infrared absorption spectrum of the coating layer, the peak intensity (P1) of a peak having an absorption maximum in the region of 1655 ± 10 cm ⁻¹ and the peak intensity of a peak having an absorption maximum in the region of 1530 ± 10 cm ⁻¹ ( The ratio (P1 / P2) to P2) is
1.2 ≦ (P1 / P2) ≦ 4.5
Satisfy the relationship shown in
And the adhesion amount of the said coating layer is the range of 0.05-0.2 g / m < ² >, The laminated film characterized by the above-mentioned.
(2) The laminated film according to (1), wherein the resin containing an oxazoline group in the resin composition for coating layer has an oxazoline group amount of 5.1 to 9.0 mmol / g.
(3) The laminated film according to (1) or (2), wherein the resin composition for a coating layer contains a polyester resin having an acid value of 40 to 100 mgKOH / g.
(4) The above (1) to (3), wherein the urethane resin is 30 to 60% by mass and the resin having an oxazoline group is 20 to 60% by mass in 100% by mass of the total resin component of the resin composition for a coating layer. The laminated film according to any one of the above.
(5) The laminated film according to any one of (1) to (4), wherein an inorganic thin film layer is laminated on the coating layer.
(6) The laminated film according to (5), wherein the inorganic thin film layer is a layer of a composite oxide of silicon oxide and aluminum oxide.

  According to the present invention, when a gas barrier laminate film provided with an inorganic thin film layer is used, the gas barrier property is excellent not only in a normal state but also after a retort treatment, and delamination does not occur. It was possible to provide a laminated film exhibiting excellent laminate strength (adhesiveness). In addition, since the laminated film of the present invention has few processing steps and can be easily manufactured, it is excellent in both economic efficiency and production stability, and a gas barrier film having uniform characteristics can be provided.

  The laminated film of the present invention is one in which a coating layer is provided on at least one side of a plastic substrate film. First, the plastic substrate film will be described, and then the coating layer, the inorganic thin film layer, and other layers laminated thereon will be described.

[Plastic base film]
As a plastic base film (hereinafter referred to as “base film”) used in the present invention, for example, plastic is melt-extruded and stretched in the longitudinal direction and / or the width direction, cooled, and heat-set as necessary. A film can be used. Examples of plastics include polyamides represented by nylon 4, 6, nylon 6, nylon 6, 6, nylon 12, etc .; polyesters represented by polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, etc .; polyethylene, polypropylene In addition to polyolefins such as polybutene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, wholly aromatic polyamide, polyamideimide, polyimide, polyetherimide, polysulfone, polystyrene, and polylactic acid. Among these, polyester is preferable in terms of heat resistance, step stability, and transparency, and polyethylene terephthalate or a copolymer obtained by copolymerizing polyethylene terephthalate with other components is particularly preferable.

As a base film, those having an arbitrary film thickness can be used according to desired purposes such as mechanical strength and transparency, and the film thickness is not particularly limited, but is usually 5 to 250 μm. Is recommended, and when used as a packaging material, it is preferably 10 to 60 μm.
The transparency of the base film is not particularly limited, but when used as a packaging material that requires transparency, a film having a light transmittance of 50% or more is desirable.

The base film may be a single-layer film made of one kind of plastic or a laminated film in which two or more kinds of plastic films are laminated. There are no particular limitations on the type of laminate, the number of laminations, the lamination method, and the like in the case of a laminated film, and any one of known methods can be selected according to the purpose.
The base film may be subjected to surface treatment such as corona discharge treatment, glow discharge, flame treatment, surface roughening treatment, etc., as long as the object of the present invention is not impaired. Processing, printing, decoration and the like may be performed.

[Coating layer]
In the present invention, the coating layer is obtained from a resin composition for a coating layer containing a urethane resin having metaxylylene diisocyanate and / or hydrogenated metaxylylene diisocyanate as main components and a resin having an oxazoline group. is there. At this time, the ratio of the metaxylylene diisocyanate and / or hydrogenated metaxylylene diisocyanate component in the urethane resin to the whole polyisocyanate component is 50 mol% or more. Further, in the total reflection infrared absorption spectrum of the coating layer, the ratio of two predetermined peak intensities (P1 / P2) is in a specific range, and the coating amount of the coating layer is in a specific range. As a result, excellent bath barrier properties and laminate strength can be maintained even after the retort treatment. Hereinafter, the action mechanism of maintaining the gas barrier property and the laminate strength excellent in the normal state and after the retort treatment by the configuration of the coating layer will be described.

  Conventionally, in a laminated film in which a coating layer and an inorganic thin film layer are laminated on a base film, a method of separately improving the gas barrier properties of the inorganic thin film layer or the coating layer itself has been adopted in order to improve the gas barrier property. .

  The coating layer of this invention contains the urethane resin which has metaxylylene diisocyanate and / or hydrogenated metaxylylene diisocyanate as a main structural component. This urethane resin has a gas barrier property because of its high cohesive force due to its hydrogen bonding force. This resin also has a side surface that forms a highly hydrophilic surface derived from urethane bonds. For this reason, when it uses as a foundation | substrate of the inorganic thin film layer formed by a vapor deposition method, it similarly has the characteristic that the inorganic substance which is hydrophilic is easy to deposit uniformly and densely. In addition, the present inventors use such a urethane resin in combination with a hydrophilic cross-linking agent such as a resin having an oxazoline group, and if necessary, in combination with an aqueous resin having a high acid value, It has been found that the characteristics of the urethane resin can be more effectively exhibited. This makes it possible for the inorganic substance attracted to the hydrophilic group in the urethane bond to interact with the hydrophilic group of other resin in the vicinity, thereby promoting the formation of a strong and dense inorganic thin film. The Rukoto. As a result, the gas barrier property of the inorganic thin film layer can be improved.

  The present inventors have also found that the gas barrier property improving effect described above can be maintained even after retorting. Conventionally, in the case of a laminated film provided with an inorganic thin film layer, if the adhesion between the inorganic thin film layer and the base film, or the base film and the coating layer provided thereon is inadequate, the interlayer is formed when retorting is performed. Water entered the film and peeling occurred at the interface with the inorganic thin film layer. Then, the peeled portion was used as a trigger, and the inorganic thin film layer was cracked or floated. As a result, there was a problem that gas barrier properties and laminate strength were lowered.

Further, delamination during retort treatment also occurs between the base film and the coating layer. That is, at the time of the retort treatment, a plastic such as a polyester resin constituting the base film or a resin in the coating layer may be hydrolyzed and the bond may be broken. As a result, adhesion failure between the base film and the coating layer may occur, and the gas barrier property and laminate strength may be reduced as described above.
Furthermore, at the time of a retort process, the below-mentioned sealant layer provided on the base film or the inorganic thin film layer is subjected to a dimensional change by being exposed to a moist heat environment, and a stress load is applied to the adjacent inorganic thin film layer. As a result, the inorganic thin film layer may be destroyed and the barrier property may be lowered.

  However, since the coating layer of the present invention contains a urethane resin mainly containing metaxylylene diisocyanate and / or hydrogenated metaxylylene diisocyanate and an oxazoline group-containing resin, (hydrogenated) xylylene groups are The stacking effect of the urethane resin further increases the cohesive strength of the urethane resin, and the cross-linked structure is formed in the coating layer by the oxazoline group-containing resin. At the same time, the oxazoline group remains in the coating layer. It contributes to maintaining the property and adhesion, and can exhibit high performance.

  In addition, the oxazoline group has a high affinity with inorganic substances due to its hydrophilicity, and can interact with oxygen deficient portions of inorganic oxides and metal hydroxides that are generated during the formation of inorganic thin film layers, thus providing strong adhesion to inorganic thin film layers. Showing gender. Further, the unreacted oxazoline group present in the coating layer can react with the carboxylic acid terminal generated by hydrolysis of the base film and the carboxylic acid terminal present in the coating layer to form a crosslink. By such an action, in the present invention, even during retorting, the adhesion between each layer of the inorganic thin film layer-coating layer-base film is strengthened, and as a result, cracking and deterioration of the inorganic thin film can be prevented. , Gas barrier properties and laminate strength can be maintained.

In order to express the above effects, in the present invention, the peak intensity (P1) of the peak having an absorption maximum in the region of 1655 ± 10 cm ⁻¹ and 1530 ± 10 cm in the total reflection infrared absorption spectrum of the coating layer. The ratio (P1 / P2) to the peak intensity (P2) of the peak having the absorption maximum in the region of ⁻¹ is the following formula
1.2 ≦ (P1 / P2) ≦ 4.5
It is necessary to satisfy the relationship shown in. Here, the peak having the absorption maximum in the region of 1655 ± 10 cm ⁻¹ is derived from the oxazoline group, and the peak having the absorption maximum in the region of 1530 ± 10 cm ⁻¹ is derived from the polyurethane. That is, the above formula is an index representing the abundance ratio of the oxazoline group and the polyurethane bond in the coating layer, and shows an optimum existence range for the effective interaction between the oxazoline group and the urethane. In the above formula, the value represented by (P1 / P2) is preferably 1.25 or more, more preferably 1.3 or more, preferably 4.45 or less, more preferably 4.3 or less, particularly Preferably it is 4.0 or less. When the value represented by (P1 / P2) is less than 1.2, the amount of oxazoline group is small, and thus sufficient gas barrier properties and laminate strength may not be obtained after retorting. On the other hand, when the value represented by (P1 / P2) exceeds 4.5, there are cases where the effect of improving gas barrier properties cannot be obtained because polyurethane is small. Moreover, when there are too many amounts of oxazoline groups, cohesion force will fall and there exists a possibility that gas barrier property and interlayer adhesiveness may fall after a retort process. In addition, the total reflection infrared absorption spectrum measurement of a coating layer can be performed by the method as described in the Example mentioned later, for example.

Furthermore, in this invention, the adhesion amount of a coating layer shall be 0.05-0.2 g / m < ² >. Thereby, since the coating layer can be controlled uniformly, the hydrophilicity of the surface of the coating layer can be utilized to the maximum, and as a result, the inorganic thin film layer can be densely deposited. Moreover, since the cohesive force of coating layer itself improves and the adhesiveness between each layer of an inorganic thin film layer-coating layer-base film becomes high, the water resistance of a coating layer can also be improved. The coating amount of the coating layer is preferably 0.06 g / m ² or more, more preferably 0.07 g / m ² or more, further preferably 0.08 g / m ² or more, preferably 0.19 g / m ² or less. , more preferably 0.18 g / m ^2, more preferably not more than 0.170 g / m ^2. If the coating layer adhesion amount exceeds 0.2 g / m ² , the cohesive force inside the coating layer becomes insufficient, and the uniformity of the coating layer also deteriorates, resulting in defects in the inorganic thin film layer, and retort processing. There are cases where the front and rear oxygen barrier properties and water vapor barrier properties cannot be fully expressed. Moreover, not only the gas barrier property is lowered, but also the production cost is increased, which is economically disadvantageous. On the other hand, if the thickness of the coating layer is less than 0.05 g / m ² , sufficient gas barrier properties and interlayer adhesion may not be obtained.

  From the above, when the laminated film of the present invention is a gas barrier laminated film having an inorganic thin film layer, it maintains excellent gas barrier properties and interlayer adhesion (laminate strength) even after retorting. Can do.

  Next, the constituent components of the coating layer resin composition for forming the coating layer will be described in detail.

(Urethane resin)
In the present invention, it is necessary to use a urethane resin mainly composed of metaxylylene diisocyanate and / or hydrogenated metaxylylene diisocyanate. The ratio of the metaxylylene diisocyanate and / or hydrogenated metaxylylene diisocyanate component in the urethane resin to the whole polyisocyanate component is 50 mol% or more.

  Thereby, the various effects of the urethane resin described above are sufficiently exhibited, and in particular, the oxygen barrier property and the water vapor barrier property can be improved. This urethane resin is preferably produced using metaxylylene diisocyanate and / or hydrogenated metaxylylene diisocyanate as the polyisocyanate component (A) which is one of the raw materials.

  In the present invention, the proportion of the total amount of metaxylylene diisocyanate and hydrogenated metaxylylene diisocyanate in the urethane resin is 50 mol% or more (50 to 100 mol%) in 100 mol% of the polyisocyanate component (A). Must be in range. By setting it within this range, the cohesive force of urethane bonds can be further enhanced by the stacking effect between the xylylene groups, and as a result, the gas barrier property and the surface hydrophilizing effect are improved. The ratio of the total amount of metaxylylene diisocyanate and hydrogenated metaxylylene diisocyanate is preferably from 60 to 100 mol%, more preferably from 70 to 100 mol%, still more preferably from 80 to 100 mol%. If the ratio of the total amount of metaxylylene diisocyanate and hydrogenated metaxylylene diisocyanate is less than 50 mol%, the cohesive force of the urethane bond is weakened, the water resistance decreases, and the inorganic thin film layer deposited on the coating layer is defective. Will occur.

  The urethane resin is obtained by reacting the following polyisocyanate (A) with the following polyol component (B) by an ordinary method so that the amount of metaxylylene diisocyanate and / or hydrogenated metaxylylene diisocyanate component falls within the above range. can get. Furthermore, chain extension is performed by reacting a low molecular weight compound having two or more active hydrogens such as a diol compound (for example, 1,6-hexanediol) or a diamine compound (for example, hexamethylenediamine) as a chain extender. Is also possible. In addition, “Takelac (registered trademark) WPB” series commercially available from Mitsui Chemicals, Inc. can also be used as a suitable water-based urethane resin.

(A) Polyisocyanate component Examples of the polyisocyanate component (A) that can be used for the synthesis of the urethane resin include aromatic polyisocyanate, alicyclic polyisocyanate, and aliphatic polyisocyanate. As the polyisocyanate compound, a diisocyanate compound is usually used.

  Examples of the aromatic diisocyanate include tolylene diisocyanate (2,4- or 2,6-tolylene diisocyanate or a mixture thereof) (TDI), phenylene diisocyanate (m-, p-phenylene diisocyanate or a mixture thereof), 4,4. '-Diphenyl diisocyanate, 1,5-naphthalene diisocyanate (NDI), diphenylmethane diisocyanate (4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate or mixtures thereof) (MDI) 4,4′-toluidine diisocyanate (TODI), 4,4′-diphenyl ether diisocyanate and the like. Examples of the araliphatic diisocyanate include xylylene diisocyanate (1,3- or 1,4-xylylene diisocyanate or a mixture thereof) (XDI), tetramethylxylylene diisocyanate (1,3- or 1,4-tetramethyl). Examples thereof include xylylene diisocyanate or a mixture thereof (TMXDI), ω, ω′-diisocyanate-1,4-diethylbenzene, and the like.

  Examples of the alicyclic diisocyanate include 1,3-cyclopentene diisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate), 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (iso Holodiisocyanate, IPDI), methylene bis (cyclohexyl isocyanate) (4,4'-, 2,4'- or 2,2'-methylene bis (cyclohexyl isocyanate)) (hydrogenated MDI), methylcyclohexane diisocyanate (methyl-2,4) Cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate), bis (isocyanatomethyl) cyclohexane (1,3- or 1,4-bis (iso Anetomechiru) cyclohexane or a mixture thereof) (it may be mentioned hydrogenated XDI) and the like.

  Examples of the aliphatic diisocyanate include trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate), hexamethylene. Examples thereof include diisocyanate, pentamethylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caffeate.

(B) Polyol compound As the polyol component (particularly the diol component), low molecular weight glycols to oligomers can be used, but usually from the viewpoint of gas barrier properties, alkylene glycol (for example, ethylene glycol, propylene glycol, trimethylene glycol). 1,3-butanediol, 1,4-butanediol, pentanediol, hexanediol, neopentylglycol, heptanediol, octanediol, etc., linear or branched C _2-10 alkylene glycol), (poly) Low molecular weight glycols such as oxy C _2-4 alkylene glycol (diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, etc.) are used. The preferred glycol component is a C _2-8 polyol component [eg, C _2-6 alkylene glycol (particularly ethylene glycol, 1,2- or 1,3-propylene glycol, 1,4-butanediol, 1,6-hexane). Diol, 3-methyl-1,5-pentanediol, etc.], di- or trioxy C _2-3 alkylene glycol (diethylene glycol, triethylene glycol, dipropylene glycol, etc.), and particularly preferred diol components are C _2-8 alkylene. Glycol (especially C _2-6 alkylene glycol).

These diol components can be used alone or in combination of two or more. Furthermore, if necessary, aromatic diols (for example, bisphenol A, bishydroxyethyl terephthalate, catechol, resorcin, hydroquinone, 1,3- or 1,4-xylylene diol or a mixture thereof), alicyclic diols (for example, And low molecular weight diol components such as hydrogenated bisphenol A, xylylene diol, cyclohexane diol, cyclohexane dimethanol, etc.). Furthermore, if necessary, a tri- or higher functional polyol component, for example, a polyol component such as glycerin, trimethylolethane, or trimethylolpropane can be used in combination. The polyol component preferably contains at least a C _2-8 polyol component (particularly C _2-6 alkylene glycol). The proportion of the C _2-8 polyol component (especially C _2-6 alkylene glycol) in 100% by mass of the polyol component can be selected from the range of about 50 to 100% by mass, and usually 70% by mass or more and 100% by mass or less. More preferably, it is 80 mass% or more and 100 mass% or less, More preferably, it is 90 mass% or more and 100 mass% or less.

  The urethane resin preferably has a carboxylic acid group (carboxyl group). The hydrophilic portion is increased to increase the affinity with the inorganic substance, and also serves to improve the properties of the coating layer as a reaction point with the oxazoline group. In order to introduce a carboxylic acid (salt) group into a urethane resin, for example, a polyol compound having a carboxylic acid group such as dimethylolpropionic acid or dimethylolbutanoic acid may be introduced as a copolymer component. Moreover, if a carboxylic acid group-containing urethane resin is synthesized and then neutralized with a salt forming agent, a urethane resin in an aqueous dispersion can be obtained. Specific examples of the salt forming agent include trialkylamines such as ammonia, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, tri-n-butylamine, N such as N-methylmorpholine and N-ethylmorpholine. -N-dialkylalkanolamines such as alkylmorpholines, N-dimethylethanolamine, N-diethylethanolamine and the like. These may be used alone or in combination of two or more.

(Properties of urethane resin)
The acid value of the urethane resin is preferably in the range of 10 to 60 mgKOH / g. More preferably, it is in the range of 15 to 55 mgKOH / g, and further preferably in the range of 20 to 50 mgKOH / g. When the acid value of the urethane resin is within the above range, the coating layer can maintain flexibility while partially cross-linking, and can further improve the cohesive strength and relieve the stress of the inorganic thin film.

  The urethane resin of the present invention preferably has a glass transition temperature (Tg) of 80 ° C. or higher, more preferably 90 ° C. or higher. By making Tg 80 degreeC or more, the swelling of the coating layer by the molecular motion in a retort processing process (temperature rising-heat retention-temperature decreasing) can be reduced.

  It is preferable that the content rate of a urethane resin is 30-60 mass% in 100 mass% of all the resin components in the resin composition for coating layers, More preferably, it is 35-55 mass%, More preferably, it is 40-50 mass. % Should be good. By including the urethane resin in the above range, an improvement in gas barrier properties due to surface hydrophilization can be expected.

(Resin having an oxazoline group)
The coating layer of the present invention also needs to contain a component derived from a resin having an oxazoline group. Therefore, the resin composition for coating layers contains resin which has an oxazoline group. As the resin having an oxazoline group, for example, a polymerizable unsaturated monomer having an oxazoline group may be combined with other polymerizable unsaturated monomers as required by a conventionally known method (for example, solution polymerization, emulsion polymerization, etc.). Examples thereof include a polymer having an oxazoline group obtained by copolymerization.

  Examples of the polymerizable unsaturated monomer having an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2- Examples thereof include isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. These may be used alone or in combination of two or more.

  Other polymerizable unsaturated monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth). C1-C24 alkyl or cycloalkyl ester of (meth) acrylic acid such as acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, etc. (Meth) acrylic acid hydroxyalkyl ester having 2 to 8 carbon atoms; vinyl aromatic compounds such as styrene and vinyltoluene; (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) ) Acrylate, glycidyl (meth) adducts of acrylates and amines; polyethylene glycol (meth) acrylate; N- vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate, and (meth) acrylonitrile. These may be used alone or in combination of two or more.

  The resin having an oxazoline group used in the present invention may be a water-soluble resin or a water-dispersible resin from the viewpoint of improving compatibility with other resins, wettability, cross-linking reaction efficiency, transparency of the coating layer, and the like. preferable. In order to make a resin having an oxazoline group into a water-soluble resin or a water-dispersible resin, it is preferable to contain a hydrophilic monomer as the other polymerizable unsaturated monomer.

  Examples of hydrophilic monomers include monomers having a polyethylene glycol chain, such as 2-hydroxyethyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, (meth) acrylic acid and polyethylene glycol monoester compounds, 2- Aminoethyl (meth) acrylate and its salt, (meth) acrylamide, N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, (meth) acrylonitrile, sodium styrenesulfonate, etc. are mentioned. Among these, monomers having a polyethylene glycol chain such as methoxypolyethylene glycol (meth) acrylate having high solubility in water, monoester compounds of (meth) acrylic acid and polyethylene glycol (the molecular weight of the introduced polyethylene glycol chain is 150-700, preferably 150-200 from the viewpoint of water resistance, and 300-700 from the viewpoint of compatibility with other resins and transparency of the coating layer.

  In the copolymer consisting of a polymerizable unsaturated monomer having an oxazoline group and other polymerizable unsaturated monomers, the composition molar ratio of the polymerizable unsaturated monomer having an oxazoline group is 30 to 70 mol. %, And more preferably 40 to 65 mol%.

  The resin having an oxazoline group preferably has an oxazoline group content of 5.1 to 9.0 mmol / g. More preferably, it is in the range of 6.0 to 8.0 mmol / g. Conventionally, regarding the use of a resin having an oxazoline group for a coating layer, a use example of a resin having an oxazoline group of about 5.0 mmol / g has been reported (see, for example, Patent Document 2). Use a resin with a high base weight. By using a resin with a large amount of oxazoline groups, a cross-linked structure can be formed in the coating layer and at the same time oxazoline groups can remain in the coating layer. As a result, gas barrier properties and adhesion during retort processing Can contribute to maintenance. Such oxazoline group-containing resins are commercially available as “Epocross (registered trademark)” series from Nippon Shokubai Co., Ltd.

  The number average molecular weight of the resin having an oxazoline group is preferably in the range of 20000 to 50000, more preferably 25000 to 45000, in order to express the flexibility and cohesion of the coating layer. When the number average molecular weight is less than 20,000, the binding force when the crosslinked structure is taken increases, so that the flexibility of the coating layer during retort treatment cannot be obtained sufficiently, and the stress load on the inorganic thin film layer increases. There is a risk of doing. On the other hand, when the number average molecular weight exceeds 50,000, the cohesive force of the coating layer is not sufficient, and the water resistance may be lowered.

  The content of the resin having an oxazoline group is preferably 20 to 60% by mass, more preferably 25 to 55% by mass, and even more preferably 30% in 100% by mass of all resin components in the resin composition for coating layer. It is good to be -50 mass%. When the content ratio of the resin having an oxazoline group is less than 20% by mass, the effect of improving the water-resistant adhesion due to the oxazoline group tends not to be sufficiently exhibited. On the other hand, when the content exceeds 60% by mass, an unreacted oxazoline group is present. As a result, the value of (P1 / P2) described above tends to exceed the upper limit of the above range. As a result, the cohesive force of the coating layer becomes insufficient, and the water resistance may be lowered.

(High acid value aqueous resin)
The resin composition for a coating layer used in the present invention may contain a high acid value aqueous resin in order to improve the surface hydrophilicity and crosslinking density of the coating layer. By mixing a high acid value resin, the surface hydrophilic effect by the carboxylic acid group can be expected. Moreover, the cohesive force of a coating layer improves by partially bridge | crosslinking with an oxazoline group, and water resistance can be improved more. Examples of the resin include a polyester resin, an acrylic resin, and an olefin resin. In view of adhesiveness with the substrate, polyester resin is more preferable. The acid value of the resin is preferably 40 to 100 mgKOH / g, more preferably 45 to 95 mgKOH / g, and still more preferably 50 mg to 90 mgKOH / g. If the acid value is less than 40 mgKOH / g, the effects of surface hydrophilization and crosslinking density may not be obtained. On the other hand, when the acid value exceeds 100 mgKOH / g, the flexibility of the coating layer may decrease due to excessive progress of crosslinking, and the stability as a liquid may also decrease.

  When the resin composition for coating layers contains the said aqueous resin, it is preferable that the content rate of an aqueous resin is more than 0 to 15 mass% in 100 mass% of all the resin components in a composition, More preferably, 2 .5 to 12.5% by mass, more preferably 5 to 10% by mass.

  The coating layer resin composition may contain various known inorganic and organic additives such as an antistatic agent, a slipping agent, and an antiblocking agent, as necessary, within a range not impairing the present invention. Also good.

  The formation method of a coating layer is not specifically limited, For example, conventionally well-known methods, such as a coating method, are employable. Preferred examples of the coating method include an offline coating method and an in-line coating method. For example, in the case of the in-line coating method performed in the process of manufacturing the base film, the drying and heat treatment conditions during coating depend on the thickness of the coat and the conditions of the equipment, but are sent to the right-angled stretching process immediately after coating and stretched. It is preferable to dry in the preheating zone or stretching zone of the process. In such a case, it is usually preferable to set the temperature to about 50 to 250 ° C.

[Inorganic thin film layer]
The laminated film of the present invention may be an embodiment in which an inorganic thin film layer is further laminated on the coating layer. That is, the laminated film of the present invention is used for a gas barrier laminated film having an inorganic thin film layer, but an aspect in which an inorganic thin film layer is laminated in advance is also included in the laminated film of the present invention.

The inorganic thin film layer is a thin film made of a metal or an inorganic oxide. The material for forming the inorganic thin film layer is not particularly limited as long as it can be formed into a thin film, but from the viewpoint of gas barrier properties, inorganic oxidation such as silicon oxide (silica), aluminum oxide (alumina), a mixture of silicon oxide and aluminum oxide, etc. A thing is mentioned preferably. In particular, a composite oxide of silicon oxide and aluminum oxide is preferable from the viewpoint that both flexibility and denseness of the thin film layer can be achieved. In this composite oxide, the mixing ratio of silicon oxide and aluminum oxide is preferably such that Al is in the range of 20 to 70% by mass ratio of metal. If the Al concentration is less than 20%, the water vapor barrier property may be lowered. On the other hand, if it exceeds 70%, the inorganic thin film layer tends to be hard, and the film may be broken during the secondary processing such as printing or laminating, and the barrier property may be lowered. The silicon oxide referred to here is various silicon oxides such as SiO and SiO ₂ or a mixture thereof, and the aluminum oxide is various aluminum oxides such as AlO and Al ₂ O ₃ or a mixture thereof.

  The film thickness of the inorganic thin film layer is usually 1 to 100 nm, preferably 5 to 50 nm. If the thickness of the inorganic thin film layer is less than 1 nm, satisfactory gas barrier properties may be difficult to obtain. On the other hand, even if the thickness exceeds 100 nm, the corresponding effect of improving gas barrier properties is obtained. However, it is disadvantageous in terms of bending resistance and manufacturing cost.

The method for forming the inorganic thin film layer is not particularly limited. For example, a known vapor deposition method such as a vacuum vapor deposition method, a sputtering method, a physical vapor deposition method such as an ion plating method (PVD method), or a chemical vapor deposition method (CVD method). The law may be adopted as appropriate. Hereinafter, a typical method for forming the inorganic thin film layer will be described by taking a silicon oxide / aluminum oxide thin film as an example. For example, when the vacuum deposition method is employed, a mixture of SiO ₂ and Al ₂ O ₃ or a mixture of SiO ₂ and Al is preferably used as a deposition material. As these vapor deposition raw materials, particles are usually used. At this time, the size of each particle is desirably such that the pressure during vapor deposition does not change, and the preferred particle diameter is 1 mm to 5 mm. For heating, methods such as resistance heating, high frequency induction heating, electron beam heating, and laser heating can be employed. It is also possible to introduce reactive vapor deposition using oxygen, nitrogen, hydrogen, argon, carbon dioxide gas, water vapor or the like as a reactive gas, or using means such as ozone addition or ion assist. Furthermore, the film forming conditions can be arbitrarily changed, for example, by applying a bias to the deposition target (laminated film to be deposited) or heating or cooling the deposition target. Such a vapor deposition material, reaction gas, bias of the deposition target, heating / cooling, and the like can be similarly changed when a sputtering method or a CVD method is employed.

  The laminated film of the present invention as described above is laminated with an inorganic thin film layer when it does not have an inorganic thin film layer, and has an oxygen barrier property after retort treatment as it is when it has an inorganic thin film layer, Moreover, a gas barrier laminate film (laminate) having high interlayer adhesion and excellent laminate strength is obtained.

[Other layers]
In addition to the base film, the coating layer, and the inorganic thin film layer, the gas barrier laminated film including the inorganic thin film layer using the laminated film of the present invention includes a known gas barrier laminated film as necessary. Various layers can be provided.
For example, when a gas barrier laminated film provided with an inorganic thin film layer is used as a packaging material, it is preferable to form a heat-sealable resin layer called a sealant. The heat-sealable resin layer is usually provided on the inorganic thin film layer, but may be provided on the outer side of the base film (the surface opposite to the coating layer forming surface). The heat-sealable resin layer is usually formed by an extrusion lamination method or a dry lamination method. The thermoplastic polymer for forming the heat-sealable resin layer may be any one that can sufficiently exhibit sealant adhesion, such as polyethylene resins such as HDPE, LDPE, and LLDPE, and polypropylene resins. An ethylene-vinyl acetate copolymer, an ethylene-α-olefin random copolymer, an ionomer resin, or the like can be used.

  Further, the gas barrier laminated film having the inorganic thin film layer includes a printed layer or other plastic substrate and / or paper base between or outside the inorganic thin film layer or substrate film and the heat-sealable resin layer. At least one layer may be laminated.

  As the printing ink for forming the printing layer, aqueous and solvent-based resin-containing printing inks can be preferably used. Examples of the resin used in the printing ink include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. For printing inks, known antistatic agents, light blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, antifoaming agents, crosslinking agents, antiblocking agents, antioxidants, etc. These additives may be included. The printing method for providing the printing layer is not particularly limited, and a known printing method such as an offset printing method, a gravure printing method, a screen printing method, or the like can be used. For drying the solvent after printing, known drying methods such as hot air drying, hot roll drying and infrared drying can be used.

  On the other hand, as other plastic substrates and paper substrates, paper, polyester resin, polyamide resin, biodegradable resin, and the like are preferably used from the viewpoint of obtaining sufficient rigidity and strength of the laminate. Moreover, when setting it as the film excellent in mechanical strength, stretched films, such as a biaxially stretched polyester film and a biaxially stretched nylon film, are preferable.

  In particular, when a gas barrier laminate film having an inorganic thin film layer is used as a packaging material, nylon is used to improve mechanical properties such as pinhole property and piercing strength between the inorganic thin film layer and the heat sealable resin layer. It is preferable to laminate films. Here, nylon 6, nylon 66, metaxylene adipamide and the like are usually used as the type of nylon. The thickness of the nylon film is usually 10 to 30 μm, preferably 15 to 25 μm. If the nylon film is thinner than 10 μm, the strength may be insufficient. On the other hand, if the nylon film exceeds 30 μm, the waist is strong and may not be suitable for processing. The nylon film is preferably a biaxially stretched film having a stretching ratio in each direction of vertical and horizontal of usually 2 times or more, preferably about 2.5 to 4 times.

  The laminated film of the present invention includes an embodiment having each of the above-described layers other than the coating layer and the inorganic thin film layer.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention. Unless otherwise specified, “%” means “% by mass”, and “part” means “part by mass”.

  The evaluation methods and physical property measurement methods used in each example and comparative example are as follows.

(1) Preparation of laminate laminate for evaluation On the inorganic thin film layer of each laminated film obtained in Examples and Comparative Examples, a urethane-based two-component curable adhesive (“Takelac (registered trademark) A525S manufactured by Mitsui Chemicals, Inc.). ”And“ Takenate (registered trademark) A50 ”in a ratio of 13.5: 1 (mass ratio)), and a dry laminate method, a nylon film having a thickness of 15 μm (“ N1100 ”manufactured by Toyobo Co., Ltd.) Were pasted together. Next, on this nylon film, an unstretched polypropylene film having a thickness of 70 μm (“P1147” manufactured by Toyobo Co., Ltd.) as a heat-sealable resin layer is formed by dry lamination using the same urethane-based two-component curable adhesive as described above. By laminating and aging at 40 ° C. for 4 days, a laminate gas barrier laminate for evaluation (hereinafter sometimes referred to as “laminate laminate”) was obtained. In addition, all the thickness after drying of the adhesive bond layer formed with the urethane type 2 liquid curable adhesive was about 4 micrometers.

(2) Oxygen permeability evaluation method For the laminate laminate produced in (1) above, an oxygen permeability measuring device (“OX” manufactured by MOCON Co., Ltd.) according to the electrolytic sensor method (Appendix A) of JIS-K7126-2. -TRAN 2/20 "), and the oxygen permeability in a normal state was measured in an atmosphere of a temperature of 23 ° C and a humidity of 65% RH. The oxygen permeability was measured in the direction in which oxygen permeates from the base film side of the laminate laminate to the heat-sealable resin layer side.

  On the other hand, the retort obtained by subjecting the laminate laminate produced in (1) above to retort treatment for 30 minutes in pressurized hot water at 121 ° C. and drying for 1 day (24 hours) at 40 ° C. The oxygen permeability (after retort treatment) was measured in the same manner as described above for the laminated laminate after treatment.

(3) Laminate Strength Evaluation Method The laminate laminate produced in (1) above was cut into a width of 15 mm and a length of 200 mm to form a test piece, and a Tensilon universal material testing machine under the conditions of a temperature of 23 ° C. and a relative humidity of 65%. The laminate strength (normal state) was measured using “Tensilon UMT-II-500 type” manufactured by Toyo Baldwin Co., Ltd. The laminate strength was the strength when the tensile rate was 200 mm / min, water was applied between the inorganic thin film layer and the nylon film, and peeled at a peel angle of 90 degrees.

  On the other hand, the laminate laminate produced in the above (1) is subjected to a retort treatment for 30 minutes in pressurized hot water at 121 ° C., and then immediately after the obtained laminate laminate after the retort treatment. Similarly, the test was cut out and the laminate strength (after retort treatment) was measured in the same manner as described above.

(4) Measuring method of total reflection infrared absorption spectrum of coating layer In each example and comparative example, the total reflection absorption is performed on the surface of the coating layer of each film obtained at the stage where the coating layer is laminated on the base film. The total reflection infrared absorption spectrum was measured by infrared spectroscopy, and the peak intensity (P1) of the peak having an absorption maximum in the region of 1655 ± 10 cm ⁻¹ (peak derived from oxazoline) and the region of 1530 ± 10 cm ⁻¹ The peak intensity (P2) of the peak having the absorption maximum (peak derived from polyurethane) was determined, and the intensity ratio (P1 / P2) was calculated.
In calculating the peak intensity, the peak intensity ratio (P1 / P2) was determined based on the ratio of the heights of the peaks. Note that the peak having an absorption maximum in the region of 1655 ± 10 cm ^-1, since the peak is the shoulder, and a baseline a line connecting the 1600 cm ^-1 and 1800 cm ^-1, whereas the region of 1530 ± 10 cm ^-1 The baseline of the peak having the maximum absorption at the line is the line connecting the sleeves on both sides of the peak.

(Measurement condition)
Apparatus: “VTS-60A / 896” manufactured by Varian
Single reflection ATR attachment: "Silver Gate" manufactured by SPECTRA TECH
Optical crystal: Ge
Incident angle: 45 °
Resolution: 4cm ^-1
Integration count: 128 times

(5) Measuring method of adhesion amount of coating layer In each example and comparative example, each laminated film obtained at the stage where the coating layer was laminated on the base film was used as a sample, and a test piece of 100 mm x 100 mm was prepared from this sample. The coating layer was wiped off with N, N-dimethylformamide, and the coating amount of the coating layer was calculated from the change in mass of the film before and after wiping.

(6) Amount of Oxazoline Group of Resin Having Oxazoline Group A resin containing oxazoline is freeze-dried, and a ¹ H-NMR spectrum is measured using a nuclear magnetic resonance analyzer (NMR) Gemini-200 manufactured by Varian, Inc. The absorption peak intensity derived from the above and the absorption peak intensity derived from other monomers were determined, and the amount of oxazoline group (mmol / g) was calculated from the peak intensity.

(7) Quantitative determination method of isocyanate component in urethane resin The sample was dried under reduced pressure, and ¹ H-NMR spectrum was measured using a nuclear magnetic resonance analyzer (NMR) Gemini-200 manufactured by Varian, and derived from each isocyanate component. From the integral ratio of the peak intensity, the mole% ratio of the isocyanate component was determined.

  In each Example and Comparative Example, each material used for forming the coating layer was prepared as follows.

[Resin having an oxazoline group (A-1)]
As a resin having an oxazoline group, a commercially available water-soluble oxazoline group-containing acrylate (“Epocross (registered trademark) WS-300” manufactured by Nippon Shokubai Co., Ltd .; solid content 10%) was prepared. The amount of oxazoline groups of this resin was 7.7 mmol / g, and the number average molecular weight measured by GPC was 40000.

[Urethane resin (B-1)]
As a urethane resin, a commercially available metaxylylene group-containing urethane resin dispersion ("Takelac (registered trademark) WPB341" manufactured by Mitsui Chemicals, Inc .; solid content 30%) was prepared. The acid value of this urethane resin was 25 mgKOH / g, and the glass transition temperature (Tg) measured by DSC was 130 ° C. Moreover, the ratio of the metaxylylene diisocyanate with respect to the whole polyisocyanate component measured by < ¹ > H-NMR was 85 mol%.

[Urethane resin (B-2)]
As the urethane resin, a commercially available polyester urethane resin dispersion (“Takelac (registered trademark) W605” manufactured by Mitsui Chemicals, Inc .; solid content: 30%) was prepared. The acid value of this urethane resin was 25 mgKOH / g, and the glass transition temperature (Tg) measured by DSC was 100 ° C. Moreover, the ratio of the metaxylylene diisocyanate with respect to the whole polyisocyanate component measured by < ¹ > H-NMR was 45 mol%.

[High acid value polyester resin (C-1)]
As an aqueous resin having a high acid value, an emulsion of a commercially available polyester resin having no oxazoline group (“Plus Coat (registered trademark) Z-730” manufactured by Kyoyo Chemical Co., Ltd .; solid content 25%) was prepared. The acid value of this resin was 50 mgKOH / g.

Example 1
(1) Preparation of coating liquid (resin composition for coating layer) Each material was mixed with the following mixture ratio, and the coating liquid (resin composition for coating layers) was produced. In addition, the mass ratio in terms of solid content of the resin having an oxazoline group, the urethane resin, and the polyester resin in the obtained coating solution is as shown in Table 1.
Water 26.47%
Isopropanol 25.00%
Oxazoline group-containing resin (A-1) 32.00%
Metaxylylene group-containing urethane resin (B-1) 13.33%
Polyester resin (C-1) 3.20%

(2) Production of polyester base film and lamination of coating layer After pre-crystallization of polyethylene terephthalate resin (PET) having an intrinsic viscosity of 0.62 (30 ° C., phenol / tetrachloroethane (mass ratio) = 60/40), This was dried, extruded at 280 ° C. using an extruder having a T die, and rapidly solidified on a drum having a surface temperature of 40 ° C. to obtain an amorphous sheet. Next, the obtained amorphous sheet was stretched 4.0 times at 100 ° C. in the longitudinal direction between a heating roll and a cooling roll to obtain a uniaxially stretched PET film.
Next, the coating liquid prepared in the above (1) was applied to one side of the obtained uniaxially stretched PET film by a fountain bar coating method. Then, it led to the tenter while drying, and the solvent was volatilized and dried at a preheating temperature of 100 ° C. Next, the film was stretched 4.0 times in the transverse direction at a temperature of 120 ° C., and subjected to heat setting treatment at 225 ° C. while relaxing in the transverse direction by 6%, thereby forming a biaxially stretched polyester film (plastic) having a thickness of 12 μm. A laminated film having a coating layer formed on one side of the base film was obtained.
In addition, about this laminated | multilayer film, as above-mentioned, P1 / P2 and the adhesion amount of the coating layer were measured. The results are shown in Table 1.

(3) Formation of inorganic thin film layer (vapor deposition)
Next, a composite inorganic oxide layer of silicon dioxide and aluminum oxide was formed as an inorganic thin film layer on the coating layer surface of the laminated film obtained in (2) above by an electron beam evaporation method. As the deposition source, particulate SiO ₂ (purity 99.9%) and A1 ₂ O ₃ (purity 99.9%) of about 3 mm to 5 mm were used. Here, the composition of the composite oxide layer was SiO ₂ / A1 ₂ O ₃ (mass ratio) = 60/40. The film thickness of the inorganic thin film layer (SiO ₂ / A1 ₂ O ₃ composite oxide layer) was 13 nm.

  As described above, the laminated film of the present invention in which the coating layer and the inorganic thin film layer were laminated on the base film was obtained. The resulting laminated film was evaluated for oxygen permeability and laminate strength. The results are shown in Table 1.

Examples 2-8, Comparative Examples 1-9
In preparing the coating liquid (resin composition for coating layer), the amount of each material used is adjusted so that the types of resin having an oxazoline group, urethane resin, and polyester resin and the mass ratio in terms of solid content are as shown in Table 1. Changed (At this time, the proportion of isopropanol in the total amount of the coating solution was 25.00% as in Example 1) or changed so that the coating amount of the coating layer was as shown in Table 1. Except for the above, a laminated film was produced in the same manner as in Example 1, and the oxygen permeability and the laminate strength were evaluated. The results are shown in Table 1.

  According to the present invention, an inorganic thin film having excellent gas barrier properties (oxygen barrier properties, water vapor barrier properties) and good adhesion (laminating strength) that does not cause delamination even after retort treatment as a matter of course. A gas barrier laminate film provided with a layer could be provided. Such a gas barrier laminate film has the advantages that it is easy to produce, is excellent in economic efficiency and production stability, and is easy to obtain uniform characteristics. Therefore, such a gas barrier laminate film is suitable for food packaging for retort. Without stopping, it can be widely used for industrial applications such as solar cells, electronic paper, organic EL elements, and semiconductor elements as well as packaging applications for various foods, pharmaceuticals, and industrial products.

Claims (6)

A coating layer is provided on at least one side of the plastic substrate film,
The coating layer comprises a urethane resin and a resin having an oxazoline group in which 50 mol% or more of the total polyisocyanate component is composed of a metaxylylene diisocyanate and / or a hydrogenated metaxylylene diisocyanate component. Obtained from a resin composition,
In the total reflection infrared absorption spectrum of the coating layer, the peak intensity (P1) of a peak having an absorption maximum in the region of 1655 ± 10 cm ⁻¹ and the peak intensity of a peak having an absorption maximum in the region of 1530 ± 10 cm ⁻¹ ( The ratio (P1 / P2) to P2) is
1.2 ≦ (P1 / P2) ≦ 4.5
Satisfy the relationship shown in
And the adhesion amount of the said coating layer is the range of 0.05-0.2 g / m < ² >, The laminated film characterized by the above-mentioned.   The laminated film according to claim 1, wherein the resin containing an oxazoline group in the resin composition for a coating layer has an oxazoline group amount of 5.1 to 9.0 mmol / g.   The laminated film according to claim 1 or 2, wherein the coating layer resin composition further comprises a polyester resin having an acid value of 40 to 100 mgKOH / g.   4. The resin composition according to claim 1, wherein the urethane resin is 30 to 60% by mass and the resin having an oxazoline group is 20 to 60% by mass in 100% by mass of the total resin component of the resin composition for a coating layer. Laminated film.   The laminated film according to any one of claims 1 to 4, wherein an inorganic thin film layer is laminated on the coating layer.   The laminated film according to claim 5, wherein the inorganic thin film layer is a layer of a composite oxide of silicon oxide and aluminum oxide.