JP2005186628A - Polyamide film lamination - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamide film lamination, which shows good adhesion between respective layers even in a moist state. <P>SOLUTION: The polyamide film lamination has an adhesion enhancing layer, a printing ink layer, an adhesive layer and then a sealant layer on at least one side of a polyamide film base. The adhesion enhancing layer is formed by applying a coating agent containing an aqueous dispersion of a polyester copolymer; wherein the aqueous dispersion of polyester copolymer comprises a particle of a graft polyester and an aqueous solvent, and the graft polyester has a polyester main chain and a graft unit formed of radical polymerization monomers containing a radical polymerization monomer with a hydrophilic group. The average particle diameter of the graft polyester particle is 500 nm or less and the half signal bandwidth of the carbonyl carbon originating in the polyester main chain of the graft polyester particle is 300 Hz or higher. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polyamide-based film laminate or sheet laminate having a printing ink layer, an adhesive layer and a sealant layer on a polyamide film substrate, and in particular, has good adhesion between each layer constituting the laminate, The present invention relates to a polyamide film in which delamination does not occur due to intrusion of moisture even if it is processed into a food packaging bag, a medicine packaging bag, etc. and subjected to severe treatment such as boiling water treatment and retort treatment.

  Biaxially stretched polyamide films are widely used for various applications because they are excellent in toughness, pinhole resistance, flex resistance and heat resistance. For example, it is used as a packaging film having a heat seal function. In this case, generally, a heat-sealable polyamide film obtained by forming an adhesive layer on the surface of a biaxially stretched polyamide film and providing a sealant layer thereon by a dry lamination method or an extrusion lamination method. A laminate is used. The film laminate is printed as necessary, and then formed into a bag shape, and the contents, for example, seasonings such as miso and soy sauce, moisture-containing foods such as soup and retort foods, or drugs, etc. After filling, the open portion is heat-sealed to provide a packaged product provided to general consumers.

  In general, when moisture penetrates between the layers forming the polyamide film laminate having the sealant layer as described above, there is a problem that the adhesive strength between the layers is remarkably reduced. This causes damage when used as a packaging bag. For example, when a retort food bag using a polyamide film laminate having a sealant layer is subjected to boiling water treatment or retort treatment, this problem appears remarkably, and the bag is more easily damaged.

  Further, as the packaging products are upgraded, full-color multi-color printing has become widespread, and problems such as a decrease in interlayer adhesion due to the presence of a printing ink layer also arise.

  Furthermore, when an adhesive layer is interposed between the biaxially stretched polyamide film layer and the sealant layer, depending on the type of adhesive, the adhesive force is easily affected by humidity, and in particular, a humidity curable adhesive is used. In some cases, the effect appears prominently, and there is a problem that the adhesive strength varies greatly depending on the season.

  The inventor of the present invention has good adhesion between each layer in a polyamide film laminate having a printing ink layer, an adhesive layer and a sealant layer on a polyamide film substrate, and maintained high adhesion even when wet. For the purpose of obtaining a polyamide-based film laminate, an extensive study was conducted. As a result, when a polyamide film coated with a specific polyester aqueous dispersion is used in a polyamide film laminate having a printing ink layer, an adhesive layer and a sealant layer, a packaging bag formed from this polyamide film laminate Has found that breakage due to treatment such as retort treatment and boiling water treatment can be significantly reduced, leading to the present invention.

A polyamide-based film having an adhesion-modified layer formed on at least one surface of a polyamide film substrate, wherein the adhesion-modified layer is formed by applying a coating agent containing a copolymerized polyester aqueous dispersion. The polymerized polyester aqueous dispersion includes grafted polyester particles and an aqueous solvent, and the grafted polyester is a radically polymerizable monomer including a polyester main chain and a radically polymerizable monomer having a hydrophilic group. A graft portion to be formed, wherein the polyester main chain is composed of a dicarboxylic acid component and a diol component, and the dicarboxylic acid component contains 40 to 99.5 mol% of an aromatic dicarboxylic acid, and the grafted polyester The average particle diameter of the particles is 500 nm or less, and is derived from the polyester main chain of the grafted polyester particles Half-width of the ¹³ C-NMR signal of the carbonyl carbon is 300Hz or more, a polyamide film laminate,
The adhesion-modified layer is formed by applying a coating agent to a uniaxially stretched polyamide film substrate and then drying to control the moisture content of the coated film to be in the range of 0.1 to 2%. It is prepared by performing drying and heat setting as described above, and the thickness of the adhesion-modified layer is 0.1 to 1 g / m ² .
There is a polyamide-based film, thereby achieving the above object.

  The polyamide-based film laminate of the present invention in which an adhesion-modified layer, an ink layer, an adhesive layer, and a sealant layer are sequentially formed on at least one surface of a polyamide film substrate has an adhesive-modified layer having a specific copolymer polyester aqueous system. Since it is formed of a dispersion, the adhesion between each layer is good, and in particular, the water-resistant adhesion with a sealant material laminated by dry lamination, extrusion lamination, or the like is excellent. Therefore, the packaging bag made of the laminate of the present invention has very few broken bags even when retort treatment or boiling water treatment is performed, and therefore can be widely used as a packaging bag for moisture-containing foods and medicines.

  As used herein, “dispersion” refers to an emulsion, dispersion or suspension.

  In the present specification, “grafting” refers to introducing a graft portion made of a polymer different from the main chain into the polymer main chain.

  In the present specification, the “grafted polyester” refers to a polyester having a graft portion made of a polymer different from the polyester with respect to the polyester main chain.

  In the present specification, the “aqueous solvent” refers to a solvent mainly composed of water and containing an aqueous organic solvent as necessary.

(Copolymerized polyester aqueous dispersion)
The copolymerized polyester aqueous dispersion that can be used in the present invention contains particles of grafted polyester and water, an aqueous solvent or an organic solvent, and exhibits a translucent to milky white appearance. This grafted polyester has a polyester main chain and a graft portion formed by a radical polymerizable monomer including a radical polymerizable monomer having a hydrophilic group.

  The average particle diameter of the grafted polyester particles in the copolymerized polyester aqueous dispersion measured by a laser light scattering method is 500 nm or less, preferably 10 nm to 500 nm, more preferably 10 nm to 300 nm. When the average particle diameter exceeds 500 nm, the coating film strength after coating decreases.

  The content of the grafted polyester particles in the copolymerized polyester aqueous dispersion is usually 1% to 50% by weight, preferably 3% to 30% by weight.

When ¹³ C-NMR (measuring conditions: 125 MHz, 25 ° C., measuring solvent: heavy water, DSS signal is 5 Hz or less) of a copolyester aqueous dispersion that can be used in the present invention is measured, Fourier is not applied to the weighting function. In the spectrum obtained by conversion, the half-value width of the carbonyl carbon signal derived from the polyester main chain is preferably 300 Hz or more, and the half-value width of the carbonyl carbon signal derived from the graft portion is preferably 150 Hz or less.

In general, it is known that the chemical shift, the half width, and the relaxation time in ¹³ C-NMR can be changed to reflect the surrounding environment where the observed carbon atom is located. For example, a signal of carbonyl carbon of a polymer dissolved in heavy water is observed in a range of 170 to 200 ppm, and its half width is about 300 Hz or less. On the other hand, a carbonyl carbon signal of a polymer that is insoluble in heavy water is observed in the range of 170 to 200 ppm, and its half-value width is about 300 Hz or more.

  Since the polyester main chain and graft portion in the grafted polyester particles have the half width as described above, the particles in the copolymerized polyester aqueous dispersion that can be used in the present invention have the polyester main chain in the aqueous dispersion medium. A core-shell structure as a core can be taken.

  The core-shell structure referred to here is, as is known in the art, a core portion made of a polymer that is insoluble in a dispersion medium and in an aggregated state is made of a polymer that is soluble in a dispersion medium and in a dissolved state. A two-layer structure wrapped in a shell part. This structure is characteristic of a composite polymer dispersion formed by chemically bonding polymers having different solubility in a dispersion medium to each other. It is known that the structure cannot be expressed only by mixing. Furthermore, a mixture of polymers having different solubility in a simple dispersion medium cannot exist as a dispersion having a particle size of 500 nm or less.

  Since the particles in the aqueous copolymerized polyester dispersion used in the present invention have the core-shell structure as described above, the polymer particles can be obtained without using an emulsifier or an organic cosolvent often used in conventional dispersions. The dispersion state in the dispersion medium is stabilized. This is because the resin in the shell portion forms a sufficient hydration layer and protects the dispersed polymer particles.

  The coating film obtained from such a copolymerized polyester aqueous dispersion has very good adhesion to the polyamide film. Furthermore, since the blocking resistance is very excellent, it can be used without any problem even on a film substrate having a relatively low glass transition point. Moreover, when it is set as a laminated body, adhesiveness with the adhesive used when laminating printing ink or a sealant layer is also very favorable. Therefore, by using the laminated polyamide film of the present invention, the durability of the obtained laminate can be remarkably improved in retort treatment and boiling water treatment. Further, when a soft grafted polyester having a glass transition temperature of the grafted polyester in the aqueous copolymerized polyester dispersion of 30 ° C. or lower, preferably 10 ° C. or lower is used, the durability of the laminate is further improved.

(Polyester main chain)
In the present invention, the polyester that can be used as the main chain of the grafted polyester is preferably a saturated or unsaturated polyester synthesized from at least a dicarboxylic acid component and a diol component, and the resulting polyester is a single polymer or 2 It can be a mixture of more than one polymer. A polyester that does not inherently disperse or dissolve in water is preferred. The weight average molecular weight of the polyester that can be used in the present invention is 5,000 to 100,000, preferably 5,000 to 50,000. When the weight average molecular weight is less than 5000, physical properties of the coating film such as post-processability of the dried coating film are deteriorated. Further, when the weight average molecular weight is less than 5,000, the polyester itself serving as the main chain is easily water-soluble, so that the formed grafted polyester cannot form the core-shell structure described later. When the weight average molecular weight of the polyester exceeds 100,000, water dispersion becomes difficult. From the viewpoint of water dispersion, it is preferably 100,000 or less.

  The glass transition point is 30 ° C. or lower, preferably 10 ° C. or lower.

  The dicarboxylic acid component includes at least one aromatic dicarboxylic acid, at least one aliphatic and / or alicyclic dicarboxylic acid, and at least one dicarboxylic acid having a radically polymerizable unsaturated double bond. A dicarboxylic acid mixture is preferred. The aromatic dicarboxylic acid contained in the dicarboxylic acid mixture is 30 to 99.5 mol%, preferably 40 to 99.5 mol%, and the aliphatic and / or alicyclic dicarboxylic acid is 0 to 70 mol%. The dicarboxylic acid having a radically polymerizable unsaturated double bond is preferably 0.5 to 10 mol%, preferably 2 to 7 mol%, more preferably 3 to 6 mol%. When the content of the dicarboxylic acid containing a radically polymerizable unsaturated double bond is less than 0.5 mol%, it is difficult to effectively graft the radically polymerizable monomer to the polyester, The dispersed particle size tends to increase, and the dispersion stability tends to decrease.

  As the aromatic dicarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid and the like can be used. Furthermore, sodium 5-sulfoisophthalate may be used as necessary.

  As the aliphatic dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, acid anhydrides thereof and the like can be used.

  As the alicyclic dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and acid anhydrides thereof can be used.

  Dicarboxylic acids containing radically polymerizable unsaturated double bonds include α, β-unsaturated dicarboxylic acids such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, and fats containing unsaturated double bonds. As the cyclic dicarboxylic acid, 2,5-norbornene dicarboxylic acid anhydride, tetrahydrophthalic anhydride, or the like can be used. Of these, fumaric acid, maleic acid and 2,5-norbornene dicarboxylic acid (endo-bicyclo- (2,2,1) -5-heptene-2,3-dicarboxylic acid) are preferred.

  The diol component is composed of at least one of an aliphatic glycol having 2 to 10 carbon atoms, an alicyclic glycol having 6 to 12 carbon atoms, and an ether bond-containing glycol.

  Examples of the aliphatic glycol having 2 to 10 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6 -Hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol and the like can be used.

  As the alicyclic glycol having 6 to 12 carbon atoms, 1,4-cyclohexanedimethanol or the like can be used.

  Examples of the ether bond-containing glycol include diethylene glycol, triethylene glycol, dipropylene glycol, and glycols obtained by adding 1 to several moles of ethylene oxide or propylene oxide to two phenolic hydroxyl groups of bisphenols, for example, 2,2 -Bis (4-hydroxyethoxyphenyl) propane or the like can be used. Polyethylene glycol, polypropylene glycol, and polytetramethylene glycol may be used as necessary.

  In addition to the dicarboxylic acid component and the diol component, a tri- or higher functional polycarboxylic acid and / or polyol can be copolymerized.

  Trifunctional or higher polycarboxylic acids include (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, (anhydrous) benzophenone tetracarboxylic acid, trimesic acid, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydro) Trimellitate) and the like can be used.

  As the trifunctional or higher functional polyol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, or the like can be used.

  The tri- or higher functional polycarboxylic acid and / or polyol is 0 to 5 mol%, preferably 0 to 3 mol%, based on the total polycarboxylic acid component including the dicarboxylic acid component or the total polyol component including the diol component. Can be used in a range of

(Grafted part of grafted polyester)
The graft portion of the grafted polyester that can be used in the present invention is a monomer mixture containing at least one radical polymerizable monomer having a hydrophilic group or a group that can be changed to a hydrophilic group later. It can be a derived polymer.

  The polymer constituting the graft part has a weight average molecular weight of 500 to 50,000, preferably 4,000 to 50,000. When the weight average molecular weight is less than 500, the grafting rate decreases, so that hydrophilicity cannot be sufficiently imparted to the polyester, and it is generally difficult to control the weight average molecular weight of the graft portion to less than 500. is there. The graft portion forms a hydrated layer of dispersed particles. In order to provide a hydration layer having a sufficient thickness to the particles and obtain a stable dispersion, the weight average molecule of the graft portion derived from the radical polymerizable monomer is desirably 500 or more. The upper limit of the weight average molecular weight of the graft portion of the radical polymerizable monomer is preferably 50000 as described above in view of polymerizability in solution polymerization. The molecular weight within this range is controlled by appropriately selecting the polymerization initiator amount, monomer dropping time, polymerization time, reaction solvent, and monomer composition, and appropriately combining a chain transfer agent and a polymerization inhibitor as necessary. You can do it.

  The glass transition point is 30 ° C. or lower, preferably 10 ° C. or lower.

  As the hydrophilic group of the radical polymerizable monomer, a carboxyl group, a hydroxyl group, a sulfonic acid group, an amide group, a quaternary ammonium salt, a phosphoric acid group, or the like can be used. As a group that can be changed to a hydrophilic group, an acid anhydride, glycidyl, chloro, or the like can be used. The dispersibility of the grafted polyester in water can be controlled by the hydrophilic group introduced into the polyester by grafting. Among the hydrophilic groups, the carboxyl group can accurately determine the amount of the grafted polyester introduced into the grafted polyester using an acid value known in the art, so the dispersibility of the grafted polyester in water is controlled. This is preferable.

  Examples of carboxyl group-containing radical polymerizable monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and maleic anhydride that easily generates carboxylic acid in contact with water / amine. Itaconic anhydride, methacrylic anhydride and the like can be used. Preferred carboxyl group-containing radical polymerizable monomers are acrylic acid anhydride, methacrylic acid anhydride and maleic acid anhydride.

  In addition to the above-mentioned hydrophilic group-containing radical polymerizable monomer, it is preferable to copolymerize a radical polymerizable monomer that does not contain at least one hydrophilic group. In the case of only the hydrophilic group-containing monomer, grafting to the polyester main chain does not occur smoothly, and it is difficult to obtain a good copolymerized polyester aqueous dispersion. Highly efficient grafting can be carried out only by copolymerizing a radically polymerizable monomer that does not contain at least one hydrophilic group.

  As the radically polymerizable monomer not containing a hydrophilic group, one or more combinations of monomers having an ethylenically unsaturated bond and not containing a hydrophilic group as described above are used. Examples of such monomers include acrylic esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate; Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxylpropyl methacrylate; acrylamide Acrylic acid or methacrylic acid derivatives such as N-methylolacrylamide and diacetoneacrylamide; nitriles such as acrylonitrile and methacrylonitrile; vinyl acetate and propion Vinyl esters such as vinyl and vinyl benzoate; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N -N-vinyl compounds such as vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride; styrene, α-methylstyrene, t-butyl And aromatic vinyl compounds such as styrene, vinyl toluene and vinyl naphthalenes. These monomers can be used alone or in combination of two or more.

  The use ratio of the hydrophilic group-containing monomer and the monomer that does not contain a hydrophilic group is determined in consideration of the amount of the hydrophilic group to be introduced into the grafted polyester. (Containing monomer: monomer not containing a hydrophilic group) is 95: 5 to 5:95, preferably 90:10 to 10:90, more preferably 80:20 to 40:60.

  When a carboxyl group-containing monomer is used as the hydrophilic group-containing monomer, the total acid value of the grafted polyester is 600-4000 eq. / 106 g, preferably 700-3000 eq. / 106 g, most preferably 800-2500 eq. / 106 g. Acid value is 600 eq. In the case of / 106 g or less, when the grafted polyester is dispersed in water, it is difficult to obtain a copolyester aqueous dispersion having a small particle diameter, and the dispersion stability of the copolyester aqueous dispersion is lowered. Acid value is 4000 eq. In the case of / 106 g or more, the water resistance of the adhesion-modified layer formed from the copolyester aqueous dispersion is lowered.

  The weight ratio (polyester: radically polymerizable monomer) between the polyester main chain and the graft portion in the grafted polyester is 40:60 to 95: 5, preferably 55:45 to 93: 7, and more preferably 60:40. It is in the range of ~ 90: 10.

  When the weight ratio of the polyester main chain is 40% by weight or less, the above-described excellent performance of the base polyester, that is, high processability, excellent water resistance, and excellent adhesion to various substrates can be sufficiently exhibited. On the contrary, undesirable performance of acrylic resin, that is, low processability, gloss, water resistance and the like are added. When the weight ratio of the polyester is 95% by weight or more, the hydrophilic group amount of the graft portion imparting hydrophilicity to the grafted polyester is insufficient, and a good aqueous dispersion cannot be obtained.

(Solvent for grafting reaction)
The solvent for the grafting reaction is preferably composed of an aqueous organic solvent having a boiling point of 50 to 250 ° C. Here, the aqueous organic solvent means an organic solvent having a solubility in water at 20 ° C. of at least 10 g / L or more, preferably 20 g / L or more. An aqueous organic solvent having a boiling point exceeding 250 ° C. is unsuitable because it has a low evaporation rate and cannot be sufficiently removed even by high-temperature baking of the coating film after forming the coating film. Also, in the case of an aqueous organic solvent having a boiling point of 50 ° C. or lower, when the grafting reaction is carried out using it as a solvent, an initiator that decomposes into radicals at a temperature of 50 ° C. or lower must be used. Absent.

  As an aqueous organic solvent (first group) which dissolves polyester well and dissolves a hydrophilic group, particularly a carboxyl group-containing polymerizable monomer, and a polymer thereof relatively well, esters are used. Ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cyclic ethers such as tetrahydrofuran, dioxane, and 1,3-dioxolane; glycol ethers such as ethylene glycol dimethyl ether, propylene glycol methyl ether, Propylene glycol propyl ether, ethylene glycol ethyl ether, and ethylene glycol butyl ether; carbitols such as methyl carbitol, ethyl carbitol, and butyl carbitol; glycol Or lower esters of glycol ethers such as ethylene glycol diacetate and ethylene glycol ethyl ether acetate; ketone alcohols such as diacetone alcohol; N-substituted amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; Can be mentioned.

  On the other hand, as an aqueous organic solvent (second group) that dissolves polyester relatively little but dissolves a hydrophilic monomer, particularly a polymerizable monomer containing a carboxyl group-containing polymerizable monomer, and a polymer thereof relatively well. Water, lower alcohols, lower glycols, lower carboxylic acids, lower amines and the like. Preferred are alcohols having 1 to 4 carbon atoms and glycols.

  When the grafting reaction is carried out in a single solvent, one of the first group of aqueous organic solvents can be used. When carried out in a mixed solvent, a plurality of first group aqueous organic solvents or at least one first group aqueous organic solvent and at least one second group aqueous organic solvent can be used.

  The grafting reaction can be carried out either in a single solvent from the first group of aqueous organic solvents or in a mixed solvent comprising one kind of each of the first group and the second group of aqueous organic solvents. However, in view of the progress of the grafting reaction, the appearance and properties of the grafting reaction product and the aqueous dispersion derived therefrom, a mixed solvent consisting of each of the first group and the second group of aqueous organic solvents. Is preferably used. This is because gelation of the system is likely to occur due to cross-linking between the polyester molecules in the grafting reaction of the polyester, but gelation can be prevented by using a mixed solvent as described below.

  In the first group of solvents, the polyester molecular chains are in a state of extending a wide chain, while in the mixed solvent of the first group / second group, the polyester molecular chains are entangled in a narrow string shape. The state was confirmed by measuring the viscosity of the polyesters in these solutions. In the state where the polyester molecular chain is extended, all the reaction points in the polyester main chain can contribute to the grafting reaction, so that the grafting rate of the polyester is increased, but at the same time, the rate of cross-linking between molecules is also increased. On the other hand, when the polyester molecular chain is in the form of a thread, the reaction points inside the thread cannot contribute to the grafting reaction, and at the same time, the rate of cross-linking between molecules is reduced. Thus, the state of the polyester molecule can be adjusted by selecting the type of solvent, thereby adjusting the grafting rate and intermolecular crosslinking by the grafting reaction.

  A high grafting ratio and gelation suppression can be achieved in a mixed solvent system. The optimum mixing ratio of the mixed solvent of the first group / second group may vary depending on the solubility of the polyester used, but the weight ratio of the mixed solvent of the first group / second group is usually 95: 5 to 10 : 90, preferably 90:10 to 20:80, more preferably 85:15 to 30:70.

(Radical polymerization initiator and other additives)
As the radical polymerization initiator that can be used in the present invention, organic peroxides and organic azo compounds known to those skilled in the art can be used.

  Benzoyl peroxide, t-butyl peroxypivalate as organic peroxides, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), etc. as organic azo compounds I can list them.

  The amount of radical polymerization initiator used for carrying out the grafting reaction is at least 0.2% by weight, preferably 0.5% by weight or more, based on the radical polymerizable monomer.

  In addition to the polymerization initiator, a chain transfer agent for adjusting the chain length of the graft portion, for example, octyl mercaptan, mercaptoethanol, 3-t-butyl-4-hydroxyanisole and the like may be used as necessary. In this case, it is desirable to add in the range of 0 to 5% by weight with respect to the radical polymerizable monomer.

(Grafting reaction)
The graft portion is formed by polymerization of the radical polymerizable unsaturated double bond and the radical polymerizable monomer in the polyester and / or the radical polymerizable unsaturated double bond and the radical polymerizable monomer. The reaction proceeds with the active end of the polymer. The reaction product after completion of the grafting reaction contains, in addition to the target grafted polyester, a polyester having no graft portion and a polymer of a radical polymerizable monomer not grafted with the polyester. When the ratio of the grafted polyester in the reaction product is low and the ratio of the polyester having no graft portion and the polymer of the radical polymerizable monomer not grafted is high, a dispersion having good stability is obtained. It cannot be obtained.

  Usually, the grafting reaction can be performed by adding the radical polymerizable monomer and the radical initiator at a time to the solution containing the polyester under heating, or separately taking a certain time. After the dropwise addition, the reaction can be continued by further heating with stirring for a certain period of time. Alternatively, if necessary, a part of the radical polymerizable monomer is added first, and then the remaining radical polymerizable monomer and polymerization initiator are separately added dropwise over a certain period of time, and then further constant. The grafting reaction can be carried out by continuing heating with stirring for a period of time.

  The weight ratio between the polyester and the solvent is selected so that the reaction proceeds uniformly during the polymerization process in consideration of the reactivity between the polyester and the radical polymerizable monomer and the solvent solubility of the polyester. Usually, it is in the range of 70:30 to 10:90, preferably 50:50 to 15:85.

(Water dispersion of grafted polyester)
The grafted polyester that can be used in the present invention can be dispersed in water by charging it into an aqueous medium in a solid state or by dissolving it in a hydrophilic solvent and then adding it to an aqueous medium. In particular, when a monomer having an acidic group such as a sulfonic acid group and a carboxyl group is used as a radical polymerizable monomer having a hydrophilic group, the grafted polyester is neutralized with a basic compound. The grafted polyester can be easily dispersed in water as fine particles having an average particle diameter of 500 nm or less to prepare a copolymerized polyester aqueous dispersion.

  As the basic compound, a compound that volatilizes at the time of forming a coating film, or when a curing agent described below is blended, is baked and cured. As such a basic compound, ammonia, organic amines and the like are preferable. Examples of organic amines include triethylamine, N, N-diethylethanolamine, N, N-dimethylethanolamine, aminoethanolamine, N-methyl-N, N-diethanolamine, isopropylamine, iminobispropylamine, ethylamine, diethylamine, 3-Ethoxypropylamine, 3-diethylaminopropylamine, sec-butylamine, propylamine, methylaminopropylamine, dimethylaminopropylamine, methyliminobispropylamine, 3-methoxypropylamine, monoethanolamine, diethanolamine, triethanolamine And so on.

  The amount of the basic compound used is preferably such that the carboxyl group contained in the graft portion is at least partially neutralized or completely neutralized so that the pH value of the aqueous dispersion is in the range of 5.0 to 9.0. .

  As a method for preparing a copolyester aqueous dispersion neutralized with a basic compound, after completion of the grafting reaction, the solvent is removed from the reaction solution by using an extruder or the like under reduced pressure to form a melt or solid (pellet) And then stirring the mixture under heating with heating, or immediately after the grafting reaction is completed, adding the basic compound aqueous solution into the reaction solution, and continuing the heating and stirring ( An aqueous dispersion can be prepared by a one-pot method). From the viewpoint of convenience, the one-pot method is preferable. In this case, if the boiling point of the solvent used for the grafting reaction is 100 ° C. or less, a part or all of it can be easily removed by distillation.

(Polyamide film substrate)
The polyamide that can be used for the polyamide film substrate in the present invention is obtained by, for example, polycondensation of nylon 6, 3-membered or more lactam, ω-amino acid, dibasic acid and diamine using ε-caprolactam as a main raw material. Polyamide or the like can be used.

  As lactams, in addition to ε-caprolactam, enantolactam, capryl lactam, lauryl lactam, and the like can be used.

  As the ω-amino acid, 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid and the like can be used.

  Dibasic acids include adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecadioic acid, hexadecadioic acid, eicosandioic acid, eicosadienedioic acid, 2,2, 4-Trimethyladipic acid, terephthalic acid isophthalic acid, 2,6-naphthalenedicarboxylic acid, xylylenedicarboxylic acid and the like can be used.

  Examples of diamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, pentamethylenediamine, undecamethylenediamine, 2,2,4 (or 2,4,4) -trimethylhexamethylenediamine, cyclohexanediamine, Bis- (4,4′-aminocyclohexyl) methane, metaxylylenediamine, and the like can be used.

  Examples of the polymer or copolymer obtained by polycondensation of dibasic acid and diamine include, for example, nylon 6, 7, 11, 12, 6.6, 6.9, 6.11, 6.12, 6T, 6I. , MXD6, 6 / 6.6, 6/12, 6 / 6T, 6 / 6I, 6 / MXD6, and the like.

  The polyamide film substrate that can be used in the present invention may contain various additives as long as the target performance is not impaired. Examples of the additive include an antioxidant, a light resistance agent, an antigelling agent, a lubricant, an antiblocking agent, a pigment, an antistatic agent, and a surfactant.

  The polyamide film substrate that can be used in the present invention can be formed by a known film forming method. As the film forming method, a T-die method, an inflation method, or the like can be used.

  The polyamide film substrate that can be used in the present invention can be a single layer or a multilayer film by coextrusion.

(Adhesion modified layer)
In the polyamide film laminate of the present invention, the adhesion modifying layer present on at least one side of the polyamide film substrate is formed by applying a coating agent containing the above copolymerized polyester aqueous dispersion on the polyamide film substrate. The

  The above-mentioned copolymerized polyester aqueous dispersion can be used as it is as a coating agent for forming an adhesion-modified layer, but it can be used as an adhesive-modified layer by adding a crosslinking agent (curing resin) and curing. Water resistance can be imparted.

  As a cross-linking agent, phenol formaldehyde resin of a condensate of alkylated phenols, cresols and the like with formaldehyde; adduct of urea, melamine, benzoguanamine, etc. with formaldehyde, this adduct and alcohol having 1 to 6 carbon atoms An amino resin such as an alkyl ether compound comprising: a polyfunctional epoxy compound; a polyfunctional isocyanate compound; a blocked isocyanate compound; a polyfunctional aziridine compound; an oxazoline compound, and the like.

  Examples of the phenol formaldehyde resin include alkylated (methyl, ethyl, propyl, isopropyl or butyl) phenol, p-tert-amylphenol, 4, 4′-sec-butylidenephenol, p-tert-butylphenol, o-, m-, p-cresol, p-cyclohexylphenol, 4,4'-isopropylidenephenol, p-nonylphenol, p-octylphenol, 3-pentadecylphenol, phenol, phenyl o-cresol, p-phenylphenol, xylenol, etc. Mention may be made of condensates of phenols and formaldehyde.

  Examples of amino resins include methoxylated methylol urea, methoxylated methylol N, N-ethylene urea, methoxylated methylol dicyandiamide, methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylated methylol melamine, butoxylated methylol benzoguanamine, and the like. Are preferably methoxylated methylol melamine, butoxylated methylol melamine, methylolated benzoguanamine, and the like.

  Examples of the polyfunctional epoxy compound include diglycidyl ether of bisphenol A and oligomer thereof, diglycidyl ether of hydrogenated bisphenol A and oligomer thereof, orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p-oxybenzoic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, ethylene glycol diglycidyl ether, propylene Glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether and Polyalkylene glycol diglycidyl ethers, trimellitic acid triglycidyl ester, triglycidyl isocyanurate, 1,4-diglycidyloxybenzene, diglycidyl propylene urea, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol triglycidyl Examples include ether, triglycidyl ether of glycerol alkylene oxide adduct, and the like.

  As the polyfunctional isocyanate compound, a low-molecular or high-molecular aromatic or aliphatic diisocyanate or a trivalent or higher polyisocyanate can be used. Examples of polyisocyanates include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and trimers of these isocyanate compounds. There is. Furthermore, an excess amount of these isocyanate compounds and low molecular active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, or polyester polyols, poly The terminal isocyanate group containing compound obtained by making it react with polymer active hydrogen compounds, such as ether polyols and polyamides, can be mentioned.

  The blocked isocyanate can be prepared by subjecting the above isocyanate compound and blocking agent to an addition reaction by a conventionally known appropriate method. Examples of the isocyanate blocking agent include phenols such as phenol, cresol, xylenol, resorcinol, nitrophenol and chlorophenol; thiophenols such as thiophenol and methylthiophenol; oximes such as acetoxime, methylethylketoxime and cyclohexanone oxime; Alcohols such as methanol, ethanol, propanol and butanol; halogen-substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol; tertiary alcohols such as t-butanol and t-pentanol; -Lactams such as caprolactam, δ-valerolactam, ν-butyrolactam, β-propyllactam; aromatic amines; imides; acetylacetone, acetoacetate ester , Active methylene compounds such as malonic acid ethyl ester; mercaptans; imines; ureas; diaryl compounds; and sodium bisulfite and the like.

  These crosslinking agents may be used alone or in combination of two or more.

  As a compounding quantity of a crosslinking agent, 5 to 40 weight% is preferable with respect to grafted polyester.

  As a method of blending the crosslinking agent, (1) when the crosslinking agent is water-soluble, directly dissolving or dispersing in the aqueous dispersion, or (2) when the crosslinking agent is oil-soluble, after completion of the grafting reaction Alternatively, a method of adding a cross-linking agent before or after water dispersion to coexist with polyester in the core part can be used. These methods can be appropriately selected depending on the type and properties of the crosslinking agent. Further, a curing agent or an accelerator can be used in combination with the crosslinking agent.

  Additives such as antistatic agents, inorganic lubricants, and organic lubricants can be mixed with the coating agent that can be used in the present invention as long as the effects of the present invention are not impaired.

  The adhesive modified layer that can be used in the present invention can further contain additives such as antistatic agents, inorganic lubricants, organic lubricants and the like within a range not impairing the effects of the present invention. And applied to the substrate surface.

  As a method of applying a coating agent containing a copolymerized polyester aqueous dispersion to a polyamide film substrate in order to form an adhesion modified layer, known methods such as gravure method, reverse method, die method, bar method, dip method, etc. A scheme may be used.

The coating amount of the coating agent, 0.01 to 1 g / m ² as solids, preferably coated so as to 0.02 to 0.5 g / m ^2. When the coating amount is 0.01 g / m ² or less, sufficient adhesion strength between the adhesion modified layer and the other layers cannot be obtained. When it becomes 1 g / m ² or more, blocking occurs, which causes a practical problem.

  The adhesion-modified layer is applied to the biaxially stretched polyamide film base material, or applied to the unstretched or uniaxially stretched polyamide film base material, and then dried. It can be prepared by stretching or biaxial stretching followed by heat setting. When a biaxially stretched polyamide film substrate is used, the drying temperature after application of the coating agent is 150 ° C or higher, preferably 200 ° C or higher. The adhesion between the layer and the polyamide film substrate is improved.

  When extending | stretching after application | coating, it is necessary to control the moisture content of an application | coating film in the range of 0.1 to 2%, in order for the drying after application | coating not to impair the stretchability of an application | coating film. After stretching, drying and heat-setting at 200 ° C. or higher greatly improves the adhesion between the re-adhesion modified layer having a strong coating film and the polyamide film substrate.

(Ink layer)
In the polyamide-based film laminate of the present invention, an ink layer is laminated on an adhesion modified layer formed on a polyamide film substrate.

  As the printing ink for forming the ink layer, an ink using a cellulose derivative as a binder or a gravure ink using a synthetic resin as a binder can be mainly used. In particular, when water resistance is required, a curing agent can be added to an ink containing vinyl chloride, polyester, polyether, polyol or the like having a hydroxyl group at the end of the polymer chain as a binder. The ink layer is formed entirely or partially on the adhesion modified layer or as an arbitrary pattern.

(Adhesive layer)
In the polyamide film laminate of the present invention, an adhesive layer is laminated on the ink layer. The thickness of the adhesive layer is usually 0.1 μm to 10 μm.

  As the adhesive forming the adhesive layer, when the sealant layer laminated on the adhesive layer is laminated by extrusion lamination, an isocyanate-based adhesive is preferable. As the isocyanate-based adhesive, for example, a polyurethane or a polyurethane prepolymer that is a reaction product of diisocyanate and a polyhydric alcohol and has an isocyanate group at a molecular end can be used as a one-pack type. Alternatively, a two-component type in which a polyisocyanate and a polyurethane prepolymer having a polyol or a hydroxyl group at a molecular terminal are mixed immediately before use can be used.

  When the sealant layer to be laminated on the adhesive layer is laminated by dry lamination, vinyl-based, acrylic-based, polyamide-based, epoxy-based, and urethane-based adhesives known to those skilled in the art can be used as the adhesive. . Among these, a two-component polyurethane adhesive in which polyisocyanate and polyol are mixed immediately before use is preferable.

  The adhesive layer can be formed by applying the liquid adhesive on the ink layer using a method known to those skilled in the art.

(Sealant layer)
In the polyamide-based film laminate of the present invention, a sealant layer is laminated on the adhesive layer. The thickness of the sealant layer is usually 20 μm to 100 μm. The sealant layer can be formed by extruding or dry laminating a synthetic resin such as low density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), ionomer, polypropylene (PP).

  The adhesion-modified layer that can be used in the laminate of the present invention is formed by applying a coating agent containing a copolymerized polyester aqueous dispersion, and the copolymerized polyester aqueous dispersion comprises grafted polyester particles, an aqueous solvent, The grafted polyester has a polyester main chain and a graft portion formed by a radical polymerizable monomer including a radical polymerizable monomer having a hydrophilic group.

  Hereinafter, the present invention will be described using examples. In the examples, “part” simply means “part by weight” and “%” means “% by weight”. Each measurement item followed the following method.

Weight average molecular weight 0.03 g of the polymer was dissolved in 10 ml of tetrahydrofuran and measured with a GPC-LALLS apparatus low-angle light scattering photometer LS-8000 (manufactured by Tosoh Corporation, tetrahydrofuran solvent, reference: polystyrene).

Graft efficiency of polyester The product obtained by the grafting reaction was subjected to ¹ H-NMR (220 MHz, 220 MHz, proton) derived from the double bond of the double bond-containing component in the polyester using UNITY 500 (manufactured by Varian). The measurement solvent CDC1 ₃ / DMSO-d ₆ ) was measured, and the graft efficiency was calculated using the following formula based on the intensity change of the signal.

(Equation 1)
Polyester graft efficiency = (1- (Relative strength of signal derived from double bond of double bond-containing component in grafted polyester ester / Relative strength of signal derived from double bond of component containing double bond in raw polyester) Strength)) x 100) (%)

  The relative intensity was calculated by comparison with the signal intensity of internal internal as a reference signal.

Measurement of the weight average molecular weight of the grafted portion The polyester was hydrolyzed by refluxing the grafted polyester in a KOH / water-methanol solution. The decomposition product was extracted with THF under acidic conditions, and the grafted portion was purified from the extract by reprecipitation with hexane. The molecular weight of the obtained polymer was measured using a GPC apparatus (manufactured by Shimadzu Corporation, tetrahydrofuran solvent, polystyrene conversion), and the weight average molecular weight of the graft portion was calculated.

Particle size of aqueous dispersion The aqueous dispersion was prepared to a solid content concentration of 0.1 wt% using only ion-exchanged water, and particles were obtained at 20 ° C. using a laser light scattering particle size distribution analyzer Coulter model N4 (manufactured by Coulter). The diameter was measured.

B-type viscosity of aqueous dispersion The viscosity of the aqueous dispersion was measured at 25 ° C using a rotational viscometer (manufactured by Tokyo Keiki Co., Ltd., EM type).

(6) Measurement of half width of ¹³ C-NMR signal The aqueous dispersion was diluted with heavy water so as to have a solid concentration of 20% by weight, and then DSS was added thereto to prepare a measurement sample. Using UNITY 500 (manufactured by Varian), the measurement conditions were set so that the DSS signal was 5 Hz or less at 25 ° C., and then ¹³ C-NMR (125 MHz) of the sample was measured, and the weighting function was not applied. Fourier transform. The half-value widths of the carbonyl carbon signal of the obtained polyester main chain and the carbonyl carbon signal of the graft portion were measured.

Glass transition point (Tg)
The aqueous dispersion was applied to a glass plate and then dried at 170 ° C. to obtain a polyester solid. 10 mg of this polyester solid content was taken into a sample pan and scanned at a rate of 10 ° C./min with a differential scanning calorimeter to measure Tg.

Peel strength The peel strength of the polyamide film laminate during normal storage (dry and wet) was measured by a 90 ° peel test with a tensile tester at a pulling rate of 100 mm / min.

Measurement of peel strength in hot water The peel strength of the polyamide film laminate in hot water at 90 ° C. was measured by a 90 ° peel test at a tensile rate of 100 mm / min with a tensile tester.

(Example 1)
(Preparation of copolymerized polyester aqueous dispersion)
In a stainless steel autoclave equipped with a stirrer, thermometer and partial reflux condenser, 466 parts of dimethyl terephthalate, 466 parts of dimethyl isophthalate, 401 parts of neopentyl glycol, 443 parts of ethylene glycol, and 0.52 of tetra-n-butyl titanate The ester exchange reaction was carried out at 160 ° C. to 220 ° C. for 4 hours. Next, 23 parts of fumaric acid was added and the temperature was raised from 200 ° C. to 220 ° C. over 1 hour to carry out an esterification reaction. Next, the temperature was raised to 255 ° C., the pressure of the reaction system was gradually reduced, and the reaction was carried out with stirring under a reduced pressure of 0.2 mmHg for 1 hour and 30 minutes to obtain a polyester. The obtained polyester was light yellow and transparent, had a glass transition temperature of 60 ° C. and a weight average molecular weight of 12,000. The composition obtained by NMR measurement and the like was as follows.

  Dicarboxylic acid component terephthalic acid 48 mol% isophthalic acid 48 mol% fumaric acid 4 mol% diol component neopentyl glycol 50 mol% ethylene glycol 50 mol% A reactor equipped with a stirrer, thermometer, reflux device and quantitative dropping device, 75 parts of the polyester resin, 56 parts of methyl ethyl ketone and 19 parts of isopropyl alcohol were added and heated and stirred at 65 ° C. to dissolve the resin. After the resin was completely dissolved, a solution of 17.5 parts of methacrylic acid and 7.5 parts of ethyl acrylate and 1.2 parts of azobisdimethylvaleronitrile dissolved in 25 parts of methyl ethyl ketone was added at 0.2 ml / min. Was added dropwise to the polyester solution, and stirring was further continued for 2 hours after the completion of the dropping. After sampling for analysis (5 g) from the reaction solution, 300 parts of water and 25 parts of triethylamine were added to the reaction solution and stirred for 1 hour to prepare a grafted polyester dispersion. Thereafter, the temperature of the obtained dispersion was raised to 100 ° C., and methyl ethyl ketone, isopropyl alcohol and excess triethylamine were distilled off by distillation to obtain a copolymerized polyester aqueous dispersion.

The obtained dispersion was white and had an average particle diameter of 300 nm and a B-type viscosity at 25 ° C. of 50 cps. After adding 1.25 g of heavy water to 5 g of this dispersion to make the solid content concentration 20% by weight, DSS was added and 125 MHz ¹³ C-NMR was measured. The half width of the carbonyl carbon signal (160-175 ppm) of the polyester main chain was ∞ (no signal was detected), and the half width of the carbonyl carbon signal (181 ppm-186 ppm) of the methacrylic acid in the graft portion was 110 Hz. . At the end of the grafting reaction, the sampled solution is dried under vacuum at 100 ° C. for 8 hours, and the solid content is measured for acid value, polyester grafting efficiency (NMR measurement), and grafted part by hydrolysis. The molecular weight of was measured. The acid value of the solid content is 2300 eq. / 106 g. ^{In 1} H-NMR measurement, no fumaric acid-derived signal (δ = 6.8-6.9 ppm, doublet) was detected, and it was confirmed that the graft efficiency of polyester was 100%. The weight average molecular weight of the graft portion was 10,000.

(Formation of adhesion modified layer)
The dispersion was diluted with water to a solid content concentration of 5%, applied to a biaxially stretched polyamide film having a thickness of 15 μm by a gravure method, and then dried at 150 ° C. to prepare an adhesion modified layer. The amount of grafted polyester applied to the resulting film was 0.2 g / m ² .

(Preparation of laminate)
Gravure ink (Lamiace 61 white two-component type, manufactured by Toyo Ink Co., Ltd.) is gravure-printed on the coated surface of the laminated polyamide film to form a printing ink layer, and then a one-component moisture-curing AC agent ( T-104, manufactured by Nippon Soda Co., Ltd.) was applied to form an AC agent layer. Next, LDPE extrusion lamination was performed on the AC agent layer in accordance with a conventional method to provide a sealant layer, thereby obtaining a polyamide film laminate. Normal state storage (during dry and wet) and peel strength in 90 ° C. hot water were measured. The evaluation results are shown in Table 1.

(Example 2)
A coating agent was prepared by diluting the copolymerized polyester aqueous dispersion of Example 1 with water so that the solid concentration was 10%. Polyamide was heated and melted at 260 ° C. with a screw extruder and extruded through a T die. Next, the unstretched sheet was stretched by 3.2 times at 50 ° C. with a cooling drum. A coating agent is applied to the obtained polyamide film substrate by a gravure method so that the coating amount becomes 4 g / m ² , and then dried so that the moisture content of the coated polyamide film becomes 1%, and then at 120 ° C. The film was stretched 4 times and heat-fixed at 220 ° C. to obtain a polyamide film having an adhesion modified layer having a thickness of 15 μm. The coating amount of the grafted polyester was 0.2 g / m ² . Next, a polyamide-based film laminate was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Example 3)
A polyester having the following composition was obtained using the same method as in Example 1. The obtained polyester had a glass transition temperature of −10 ° C.

  Dicarboxylic acid component terephthalic acid 56 mol% sebacic acid 40 mol% fumaric acid 4 mol% diol component neopentyl glycol 50 mol% ethylene glycol 50 mol% Copolyester aqueous dispersion from this polyester using the same method as in Example 1 Was prepared. The obtained dispersion was white, the average particle diameter was 200 nm, and the B-type viscosity at 25 ° C. was 90 cps. Further, using this dispersion, a polyamide film having an adhesion modified layer was obtained in the same manner as in Example 1. Next, a polyamide-based film laminate was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 4
Using the copolymerized polyester aqueous dispersion of Example 3, a polyamide film having an adhesion modified layer was obtained in the same manner as in Example 2. Next, a polyamide-based film laminate was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Example 5)
A polyester having the following composition was obtained using the same method as in Example 1. The glass transition temperature of the obtained polyester was 30 ° C.

  Dicarboxylic acid component terephthalic acid 48 mol% Isophthalic acid 39 mol% Sebacic acid 9 mol% Fumaric acid 4 mol% Diol component Neopentyl glycol 50 mol% Ethylene glycol 50 mol% Using this polyester, the same method as in Example 1 was used. A polymerized polyester aqueous dispersion was prepared. The obtained dispersion was white, the average particle diameter was 150 nm, and the B-type viscosity at 25 ° C. was 100 cps. Further, using this dispersion, a polyamide film having an adhesion modified layer was obtained in the same manner as in Example 2. Next, a polyamide-based film laminate was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Comparative Example 1)
A polyester having the following composition was obtained using the same method as in Example 1.

  Dicarboxylic acid component terephthalic acid 35 mol% isophthalic acid 35 mol% fumaric acid 30 mol% diol component neopentyl glycol 50 mol% ethylene glycol 50 mol% From this polyester, a copolymerized polyester aqueous dispersion was prepared in the same manner as in Example 1. did. The obtained dispersion was white, the average particle diameter was 10000 nm or more, and the B-type viscosity at 25 ° C. was 50 cps. The glass transition temperature was 56 ° C. Further, using this dispersion, a polyamide film having an adhesion modified layer was obtained in the same manner as in Example 1. Next, a polyamide-based film laminate was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Comparative Example 2)
(Preparation of copolymerized polyester aqueous dispersion)
In a stainless steel autoclave equipped with a stirrer, thermometer and partial reflux condenser, 388 parts of adipic acid, 339 parts of isophthalic acid, 85 parts of maleic anhydride, 112 parts of benzoic acid, 90 parts of dimethylpropionic acid, 692 parts of neopentyl glycol Then, 77 parts of water and 1.5 parts of dibutyltin oxide were charged and subjected to esterification reaction at 150 ° C. for 1.5 hours and at 190 ° C. to 220 ° C. for 4 hours to obtain a polyester. The obtained polyester was light yellow and transparent, had a glass transition temperature of 60 ° C. and a weight average molecular weight of 1200. The composition obtained by NMR measurement was as follows.

Dicarboxylic acid component Adipic acid 38 mol% Isophthalic acid 33 mol% Maleic anhydride 8 mol% Benzoic acid 11 mol% Dimethylpropionic acid 10 mol% Diol component Neopentyl glycol 100 mol% By the same method as Example 1 A polymerized polyester aqueous dispersion was obtained. The obtained dispersion was white, the average particle diameter was 300 nm, and the B-type viscosity at 25 ° C. was 100 cps or more (not measurable due to high viscosity). After adding 1.25 g of heavy water to 5 g of this aqueous dispersion to make the solid content concentration 20% by weight, DSS was added and 125 MHz ¹³ C-NMR was measured. The half width of the carbonyl carbon signal of the polyester main chain was 150 Hz, and the half width of the carbonyl carbon signal of methacrylic acid was 200 Hz.

(Preparation of polyamide film laminate)
A polyamide film having an adhesion modified layer was obtained in the same manner as in Example 1 using the above dispersion. Next, a polyamide-based film laminate was prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Comparative Example 3)
A gravure ink (Lamiace 61 white two-component type, manufactured by Toyo Ink Co., Ltd.) is gravure-printed on the corona-treated surface of a 15 μm thick biaxially stretched polyamide film with a surface tension of 53 dynes / cm by corona treatment to form a printing ink layer. Then, a one-component moisture-curing AC agent (T-104, manufactured by Nippon Soda Co., Ltd.) was applied thereon to form an AC agent layer. Next, on the AC agent layer, LDPE extrusion lamination was performed according to a conventional method to provide a sealant layer, and a polyamide film laminate was prepared and evaluated. The evaluation results are shown in Table 1.

Claims (1)

A polyamide-based film having an adhesion-modified layer formed on at least one surface of a polyamide film substrate, wherein the adhesion-modified layer is formed by applying a coating agent containing a copolymerized polyester aqueous dispersion. The polymerized polyester aqueous dispersion includes grafted polyester particles and an aqueous solvent, and the grafted polyester is a radically polymerizable monomer including a polyester main chain and a radically polymerizable monomer having a hydrophilic group. A graft portion to be formed, wherein the polyester main chain is composed of a dicarboxylic acid component and a diol component, and the dicarboxylic acid component contains 40 to 99.5 mol% of an aromatic dicarboxylic acid, and the grafted polyester The average particle diameter of the particles is 500 nm or less, and is derived from the polyester main chain of the grafted polyester particles Half-width of the ¹³ C-NMR signal of the carbonyl carbon is 300Hz or more, a polyamide film laminate,
The adhesion-modified layer is formed by applying a coating agent to a uniaxially stretched polyamide film substrate and then drying to control the moisture content of the coated film to be in the range of 0.1 to 2%. It is prepared by performing drying and heat setting as described above, and the thickness of the adhesion-modified layer is 0.1 to 1 g / m ² .
Polyamide film.