JP2006199915A - Polyester film for laminating metal plate, laminated metal plate and metal container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester laminating film excellent in adhesion with a metal plate and molding processibility and having excellent whitening resistance, to provide film-laminated metal plates, and to provide metal containers. <P>SOLUTION: The polyester film for laminating metal plate is a biaxially oriented polyester film which comprises a polyester composition having 220-250°C melting point and composed mainly of a copolyester comprising ethylene terephthalate component and ethylene isophthalate component and has <1.385 g/cm<SP>3</SP>density and <0.130 plane orientation coefficient, wherein the polyester composition comprises, based on whole acid components of the polyester composition, 2-20 mol% polyoxyalkylene glycol component having ≥3 recurring units of a ≥2C alkylene oxide unit as the ≥2C alkylene oxide unit derived from the polyoxyalkylene glycol component, and contains 0.01-0.15 wt.% wax. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyester film used for the purpose of preventing corrosion of metal containers such as soft drinks, beer, and canned foods, a film laminated metal plate obtained by laminating the film on a metal plate, and the film laminated metal plate. In particular, the present invention relates to a polyester film suitably used for a two-piece can. More specifically, a polyester film excellent in adhesion to a metal plate and can manufacturing properties (for example, drawing and ironing properties), a film laminated metal plate obtained by laminating the film on a metal plate, and the film laminated metal plate The present invention relates to a metal container formed by molding.

  Conventionally, the inner surface and outer surface of a metal can have been widely coated with a solution in which various thermosetting resins such as epoxy and phenol are dissolved or dispersed in a solvent for the purpose of preventing corrosion. Has been done. However, this method of coating the thermosetting resin has poor productivity due to the long time required to dry the paint, and also has undesirable problems such as adverse effects on the human body and environment due to the use of a large amount of organic solvent. .

  In order to solve such a problem, a method of coating a metal plate with a thermoplastic resin by a melt extrusion method is known. (For example, refer to Patent Document 1). A method of laminating a thermoplastic resin film on a metal plate is also known. (For example, refer to Patent Document 2).

  By the way, for beverage cans, in addition to the so-called three-piece cans, which are obtained by attaching lids to the upper and lower openings of a metal cylinder formed by cylindrical molding of a metal plate, the metal plate is squeezed or squeezed and ironed. There is a so-called two-piece can formed by forming a container part and winding a lid on the upper surface opening of the container part.

  However, when a polyester film mainly composed of polyethylene terephthalate is applied to a two-piece can, the moldability during drawing and ironing and the adhesion of the film to the metal plate are insufficient, causing delaminating or tearing. There is a case. This tendency appears more noticeably in a biaxially stretched film in which the film is in an oriented state.

  Therefore, in order to apply the film-laminated metal plate to a two-piece can, it is necessary to have good formability of forming following the forming of the metal plate and to have excellent adhesion to the metal plate. If the formability is insufficient or the film has insufficient adhesion to the metal plate, a so-called delaminating phenomenon occurs in which the film is peeled off from the metal plate, or the film is produced during the production of the container part of a two-piece can. Because it will be torn.

  Biaxially oriented films of various forms have been proposed as means for improving the formability of film laminated metal plates into two-piece cans. (For example, refer to Patent Document 3, Patent Document 4, and Patent Document 5) However, the methods disclosed in these documents are effective when used in a drawn can and a deep drawn can having a low deformation rate. When used for a drawn / ironing can having a large deformation rate, a sufficient effect on moldability has not been obtained.

  In addition, in order to apply the film laminate metal plate to a two-piece can, a remelt process is performed in which, after laminating, heating is performed at a temperature equal to or higher than the melting point of the polyester constituting the film in order to remove the orientation of the polyester film, followed by rapid cooling. Yes. (For example, refer to Patent Document 6). The film that has become substantially non-oriented by the remelt treatment can follow the deformation in the forming process of the drawn iron can.

  However, non-oriented films generally have lower strength than biaxially stretched films, and it is said that oligomers tend to precipitate and embrittlement tends to occur. In particular, the film for the inner surface of the can needs to have impact resistance so that the metal is not eroded by the occurrence of pinholes and cracks in the film due to the impact at the time of canning. Since the film at the bottom portion of the can that is not deformed during molding remains in a non-oriented state, the impact resistance tends to decrease. In addition, when using a molding method that punches without leaving a brim at the tip of the can body at the time of can making, the tearing property of the film is poor and beard-like film scraps accumulate in the can making process, and the case of continuous cans made industrially There was a problem of deteriorating can manufacturing.

In addition, when the deformation rate during can making is large, or when the can is made at a high speed of 100 cans / minute or more, the film laminate metal plate obtained by the above-described conventional technique can be used to extend the film. However, the problems still remain, such as film slippage (galling) on the outer surface of the can and adhesion between the film on the inner surface of the can and the punch (strip-out).
JP-A-57-203545 JP-A-4-261826 JP-A 64-22530 Japanese Patent Publication No. 8-19246 JP-A-3-93525 Japanese National Patent Publication No. 2-501638

  The object of the present invention is to solve the problems of the prior art. That is, it is providing the polyester laminated film excellent in the adhesiveness with a metal plate, and a moldability, a film lamination metal plate, and a metal container.

  As a result of diligent studies to achieve the above object, the present inventors have as a main component a copolymer polyester composed of an ethylene terephthalate component and an ethylene isophthalate component, and the density of a biaxially stretched polyester film containing a specific amount of components and By controlling the degree of in-plane orientation appropriately, it gives the film stretchability and good adhesion to the metal plate against severe deformation during drawing and ironing processing of the film laminate metal plate, and also scratches and cracks The present inventors have found that a metal can having a good appearance with no appearance can be obtained.

The present invention is as follows.
1. It consists of a polyester composition having a melting point of 220 to 250 ° C. mainly composed of a copolymer polyester composed of an ethylene terephthalate component and an ethylene isophthalate component, and has a density of less than 1.385 g / cm ³ and a plane orientation coefficient of less than 0.130. It is a biaxially oriented polyester film, and the polyester composition has a polyoxyalkylene glycol component in which the repetition of alkylene oxide units having 2 or more carbon atoms is 3 or more, and the carbon number derived from the polyoxyalkylene glycol component is 2 to 20 mol% of the total acid component of the polyester composition as two or more alkylene oxide units, and further 0.01 to 0.15 wt% of a wax. Polyester film for bonding.
2. Above 1. A polyester film for laminating a metal plate, wherein the polyester composition constituting the polyester film described in 1 contains a polyalkylene terephthalate-polytetramethylene oxide block copolymer.
3. Above 1-2. A laminated metal plate obtained by laminating the polyester film described in 1 on at least one surface of a metal plate.
4). 3. above. A metal container formed by molding the laminated metal plate described in 1.

  The polyester film of the present invention has adhesion to a metal plate, drawability and ironing ability (especially, release characteristics of can inner film and processing punch during canning under severe conditions, and scratch resistance of outer face film of can. Film laminate metal plate having excellent adhesion properties), and a metal can obtained by molding the film laminate metal plate has a good appearance, and is a very useful polyester film, film laminate metal plate, and film laminate metal. It is a metal container obtained by forming a plate.

Hereinafter, the present invention will be described in detail.
The copolymerized polyester used in the present invention is a copolymerized polyester having an ethylene terephthalate component as a main component and an ethylene isophthalate component. The ratio of the isophthalic acid component to the total acid component of the copolymerized polyester is preferably 3 to 20 mol%, and more preferably 4 to 10 mol%. The copolymerized polyester can contain other copolymerization components as long as the purpose is not impaired. Among other copolymerizable components that can be used, dicarboxylic acid components include naphthalene dicarboxylic acid, diphenylsulfone dicarboxylic acid, aromatic dicarboxylic acids such as 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, Aliphatic dicarboxylic acids such as decanedicarboxylic acid, maleic acid, fumaric acid and dimer acid, oxycarboxylic acids such as p-oxybenzoic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid can be used. The amount of the above-mentioned dicarboxylic acids and their ester derivatives that can be used is preferably 20 mol% or less, more preferably 10 mol% or less. If the amount of other dicarboxylic acids and their ester derivatives used exceeds 20 mol%, the thermal stability of the polyester is deteriorated, which is not preferable.

  Further, as the glycol component of the copolymerized polyester of the present invention, components that can be used in addition to the ethylene glycol component include aliphatic glycols such as propanediol, butanediol, pentanediol, hexanediol, neopentylglycol, cyclohexanedimethanol, etc. Aromatic glycols such as alicyclic glycol, ethylene oxide adduct of bisphenol A, ethylene oxide adduct of bisphenol S, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like can be used. In addition, a small amount of a compound containing an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be included. Here, the amount of the other glycol component that can be used is preferably 20 mol% or less, and more preferably 10 mol% or less. If the amount of the other glycol component used exceeds 20 mol%, the thermal stability of the polyester deteriorates, which is not preferable.

  In the polyester composition of the present invention, in order to improve the molding adhesion and tearability at the time of making a film-laminated metal plate, a polyoxy group having 3 or more repeating alkylene oxide units having 2 or more carbon atoms. It is necessary to contain an alkylene glycol component. By containing the said component, the elasticity at normal temperature and low temperature of a polyester composition can be provided, and the shaping | molding adhesiveness with a metal plate can be improved. In particular, it is effective in improving the formability during drawing and ironing cans that are subjected to shock deformation at high speed. Moreover, the process abnormality at the time of continuous production by the accumulation | storage of the chip | tip (whisker) by the tearability defect of the film at the time of can making can be prevented. Examples of polyoxyalkylene glycols comprising alkylene oxide units having 2 carbon atoms include polyethylene glycol (2 carbon atoms), polytrimethylene glycol (3 carbon atoms), polytetramethylene glycol (4 carbon atoms), polyhexamethylene Glycol (6 carbon atoms) can be used, and one of these components may be used alone, or two or more components may be mixed and used. A polyoxyalkylene glycol having an average molecular weight in the range of 500 to 3000 can be suitably used, and an average molecular weight in the range of 800 to 2000 is more preferable.

  The method for incorporating the above polyoxyalkylene glycol component into the polyester composition of the present invention is not particularly limited. For example, a polyester composition obtained by adding a polyoxyalkylene glycol component at the stage of producing a polyester composition in the same manner as other raw materials and then terminating the polyester synthesis reaction may be used, or a polyoxyalkylene glycol may be used. Another copolyester obtained by copolymerization of may be melt-mixed with the polyester composition of the present invention. In the present invention, the latter method of melt mixing is preferable because the effect of improving the moldability and tearability of the can is exhibited more efficiently. In particular, the polyalkylene terephthalate-polytetramethylene oxide block copolymer is melt-mixed. The method is the most preferred form.

  The amount of the polyoxyalkylene glycol component contained in the polyester composition of the present invention is such that the amount of the alkylene oxide unit having 2 or more carbon atoms derived from the polyoxyalkylene glycol component is the total acid component of the polyester composition. It is necessary that it is 2 to 20 mol%. The alkylene oxide unit having 2 or more carbon atoms derived from the polyoxyalkylene glycol component is a structural unit in which both ends of an alkylene chain form an ether bond with an adjacent alkylene chain with an oxygen atom interposed therebetween, If the amount is less than 2 mol%, the effect of improving the canability and tearability is insufficient, and if it exceeds 20 mol%, the strength and thermal properties of the film deteriorate, and the film production process and the production process of the laminated metal plate The handleability may be deteriorated.

  The melting point of the copolymerized polyester of the present invention is 220 to 250 ° C. Can manufacturing properties (ensuring release of the resin and punch on the inner surface of the can in drawing and ironing processes, galling of the resin on the outer surface of the can (resin film) This is necessary from the standpoint of ensuring vertical scratches). Furthermore, when the processing conditions at the time of can-making become severe, it is preferable to be in the range of 230 to 245 ° C. It is necessary to adjust the type and content of the copolymerization component so as to fall within the above melting point range.

  The copolymer polyester composition constituting the polyester film of the present invention may be a single composition or a blend of two or more polyester compositions having different composition ratios. In addition, a small amount of other polyester compositions represented by polybutylene terephthalate can be blended. In order to satisfy the thermal stability and moldability of the polyester film of the present invention, the total of the ethylene terephthalate component and the ethylene isophthalate component is 80 to 100 mol% as a final constituent of the entire film, and the ethylene isophthalate component is It is preferable to adjust the composition and blending so that the total content of the ethylene terephthalate component and the ethylene isophthalate component is 3 to 20 mol%, and the ethylene isophthalate component is 4 to 10 mol%. When a small amount of polybutylene terephthalate is blended, it is preferable from the viewpoint of thermal stability and moldability that the butylene terephthalate component is blended so as to be 20 mol% or less.

  It does not specifically limit about the manufacturing method of polyester of this invention. That is, it can be used even if it is produced by either the transesterification method or the direct polymerization method. Further, it may be produced by a solid phase polymerization method in order to increase the molecular weight. In addition, the amount of oligomers from the polyester resin in the retort treatment etc. that is carried out after filling the can into the can is reduced, and from the standpoint of fragrance to prevent the content and flavor from deteriorating, From the viewpoint of preventing contamination, it is preferable to use a polyester having a low oligomer content produced by a solid phase polymerization method under reduced pressure or under an inert gas atmosphere.

  Here, for example, the content of the oligomeric cyclic trimer including ethylene terephthalate cyclic trimer is preferably 0.7% by weight or less.

  The intrinsic viscosity of the polyester of the present invention is preferably 0.6 to 1.2. If the intrinsic viscosity is less than 0.6, the mechanical properties of the resulting film may be deteriorated, and even if the intrinsic viscosity exceeds 1.2, no further effect of improving the mechanical properties can be obtained. In addition, the productivity at the time of production of the polyester is lowered, which is not economical.

  In the production of the polyester in the present invention, as the polymerization catalyst, antimony oxide, germanium oxide, titanium compound, etc. are used, and in addition to the polymerization catalyst, the polyester resin composition of the present invention is used to form a melt-extruded film. In order to provide electrostatic adhesion, Mg salt such as magnesium acetate and magnesium chloride, Ca salt such as calcium acetate and calcium chloride, Mn salt such as manganese acetate and manganese chloride, Zn salt such as zinc chloride and zinc acetate, Co salt such as cobalt chloride and cobalt acetate should be added within the range of 300 ppm or less as the total amount of each metal ion, and phosphoric acid ester derivatives such as phosphoric acid or phosphoric acid trimethyl ester and phosphoric acid triethyl ester as phosphorous atoms within 200 ppm or less. Is also possible. When the total amount of metal ions other than the above polymerization catalyst exceeds 300 ppm and the amount of phosphorus exceeds 200 ppm, not only is the resulting polyester colored significantly, but the heat resistance and hydrolysis resistance of the polyester may also decrease. Therefore, it is not preferable.

  At this time, when the molar ratio of the total phosphorus amount to be added and the total metal ion amount is 0.4 to 1.0, the polyester having the best balance of heat resistance, hydrolysis resistance, and electrostatic adhesion Is preferable. Here, molar ratio of addition amount = (total amount of phosphorus in phosphoric acid, phosphoric acid alkyl ester or derivative thereof (molar atom)) / (total amount of Mg ion, Ca ion, Mn ion, Zn ion, Co ion ( Mole atom)). When the molar ratio is less than 0.4, the composition of the present invention is markedly colored, and heat resistance and hydrolysis resistance are lowered. If it exceeds 1.0, sufficient electrostatic adhesion cannot be obtained.

  Further, as described above, the polyester film of the present invention has a laminated metal even when the production conditions are severe, such as when the metal deformation ratio is increased or the processing speed is increased when the metal container is manufactured by drawing and ironing. In order to impart the slipperiness of the plate, it is preferable to use inert particles. The amount of inert particles is not particularly limited, but is preferably in the range of 0.01 to 1.0% by weight. When the film is drawn and ironed, the amount of inert particles is preferably 0.01% by weight or more in order to smoothly release from punches and dies and to prevent scratches on the film that becomes the outer surface of the can. It is. On the other hand, even if it contains an amount exceeding 1.0% by weight, the effect of preventing scratches is not changed, and only the cost is disadvantageous.

  Here, as the inert particles, it is preferable to use inert inorganic particles, crosslinked polymer particles, or the like. Examples of the inert inorganic particles include silica, alumina, kaolin clay, titanium oxide, calcium phosphate, calcium carbonate, lithium fluoride, barium sulfate, and carbon black. Moreover, as the crosslinked polymer particles, acrylic monomers such as acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, styrene monomers such as styrene and alkyl-substituted styrene, and divinylbenzene, Copolymers with crosslinking monomers such as divinyl sulfone, ethylene glycol dimethacrylate, trimethylolpropane trimethyl acrylate, pentaerythritol tetramethyl acrylate, melamine resins, benzoguanamine resins, phenol resins, silicon-containing resins, etc. Can be illustrated. Among them, the amorphous particles are preferably amorphous particles composed of aggregates of primary particles, especially the agglomerated silica particles, and the crosslinked polymer particles are preferably crosslinked polymethyl methacrylate particles.

  The average particle diameter of the inert particles is preferably 1.0 to 2.5 μm. This is because if it is less than 1.0 μm, the effect of improving the scratch resistance of the film cannot be sufficiently exhibited. On the other hand, if the thickness exceeds 2.5 μm, the effect of improving scratch resistance is saturated, but particles are likely to fall off due to wear, and film breakage may occur during lamination with a metal plate. The average particle diameter of the inert particles was measured by a 50% weight average by a Coulter counter method.

  The inert particles may be added to the polyester film in the production process of the polyester composition, or the polyester composition and the inert particles may be melt-kneaded. Moreover, you may add with the masterbatch containing a high concentration inert particle at the time of manufacture of a polyester film. The polyester film used in the present invention preferably has a coefficient of dynamic friction between the film and the metal at 80 ° C. of 0.45 or less. If the dynamic friction coefficient is 0.45 or less, the slipperiness with a die or a punch at the time of can making becomes a practical level. In order to lower the dynamic friction coefficient, it can be achieved by adding inert particles in the above-mentioned range, but it is also preferable to use a combination of inorganic particles and crosslinked polymer particles or polyester incompatible thermoplastic resins. This is an embodiment.

  As described above, the polyester film of the present invention is provided with the slidability of the laminated metal plate after being remelted to eliminate the orientation after the film is laminated to the metal plate, and a metal can is manufactured by drawing and ironing. In order to obtain good can-making properties (especially the resin and punch release properties on the inner surface of the can) even when the manufacturing conditions are severe, such as when the processing deformation ratio increases and the processing speed increases, the polyester resin composition It is necessary to contain a wax component in the product.

  The wax component contained in the polyester film of the present invention includes natural waxes such as paraffin wax, carnauba wax, lanolin wax, polyethylene wax, ester wax, glycerin from the viewpoint of workability in blending with a resin and film forming properties. It is preferable to contain one or more waxes selected from synthetic waxes such as fatty acid esters and higher fatty acid monoamides, and polyethylene wax is particularly preferable.

  The wax content in the polyester resin composition needs to be in the range of 0.01 to 0.15% by weight, and preferably 0.02 to 0.1% by weight. If the wax content is less than 0.01% by weight, it cannot be said that the effect of improving the can-making property is sufficient, and if it exceeds 0.15% by weight, no further effect of improving the can-making property can be expected. This is because the thermal stability of the composition may be impaired.

  The method for incorporating the wax into the polyester film of the present invention is not particularly limited. That is, a method of producing a film using a polymer obtained by melt-kneading polyester and wax in advance, a method of producing a film directly using a mixture of polyester and wax, and the like can be used.

  In addition to the inert particles and wax, the polyester film of the present invention includes an incompatible thermoplastic resin, an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, a pigment, and an antistatic agent as necessary. Further, additives such as a lubricant and a crystal nucleating agent may be contained. In particular, it is preferable to contain an antioxidant in order to prevent fine waviness from being generated on the surface of the remelt metal plate due to thermal degradation of the film when the film-laminated metal plate is remelted. When the laminate film is thinned, the above problem becomes remarkable, so the addition of an antioxidant is indispensable.

  Antioxidants used in the present invention include primary antioxidants (which have a phenol-based or amine-based radical scavenging and chain termination action), and secondary antioxidants (which are phosphorus-based and sulfur-based). Any of these can be used. Specific examples include phenolic antioxidants (eg, phenol type, bisphenol type, thiobisphenol type, polyphenol type, etc.), amine antioxidants (eg, diphenylamine type, quinoline type, etc.), phosphorus antioxidants (eg, For example, phosphite type, phosphonite type, and the like) and sulfur-based antioxidants (for example, thiodipropionic acid ester type and the like). Specifically, n-octadecyl-β- (4′-hydroxy-3,5′-di-t-butylphenyl) propionate, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-) 4′-hydroxyphenyl) propionate] (which is commercially available as “Irganox 1010” (trade name)), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) ) Butane, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -S-triazine-2,4,6 (1H, 3H, 5H) -trione, 1,3, 5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (which is commercially available as "Irganox 1330" (trade name)), tris ( mix Mono and / or dinonylphenyl) phosphite, cyclic neopentanetetrayl bis (octadecyl phosphite), tris (2,4-di-t-butylphenyl phosphite), 2,2-methylene bis (4,6- And di-t-butylphenyl) octyl phosphite, di-lauryl-thiodipropionate, di-myristyl-thiodipropionate, and di-stearyl-thiodipropionate. These antioxidants may be used alone or in combination of two or more.

  The content of the antioxidant for the polyester film of the present invention is preferably 0.01 to 1% by weight.

  In order to further improve the adhesion of the polyester film of the present invention to the metal plate, a two-layer structure in which another resin layer (II) is laminated on one side of the film layer (I) made of the polyester composition described above It is preferable to use a laminated film. Here, the resin constituting the resin layer (II) is more preferably a water-dispersed resin composition.

  The water-dispersed resin composition is a resin composition that is insoluble in water but can be dispersed or dissolved in an aqueous solvent. Specifically, the resin composition which copolymerized the monomer component which has a hydrophilic group in a molecule | numerator is mentioned. By using such a resin composition, it is possible to achieve excellent adhesion with a metal plate.

  Examples of the water-dispersed resin composition of the present invention include a polyester composition obtained by copolymerizing a monomer component having a hydrophilic group. The hydrophilic group is, for example, a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, or a derivative or metal base thereof, an ether group, or the like, and a monomer containing these groups in the molecule is copolymerized to form water. It exists in a dispersible state. Specific examples of the monomer containing a hydrophilic group include polyethylene glycol, polypropylene glycol, glycerin, polyglycerin, sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid. Alkali metal salts of sulfonic acid-containing monomers such as acid, sulfo-p-xylylene glycol, 2-sulfo-1,4-bis (hydroxyethoxy) benzene, 5 (4-sulfophenoxy) isophthalic acid, and their ester forming properties Derivatives. A water-dispersed polyester composition obtained by a normal polyester polymerization reaction using these monomers together with a dicarboxylic acid component and a glycol component is preferably used. Of the above monomers, sodium and potassium salts of 5-sulfoisophthalic acid and sulfoterephthalic acid are more preferable.

  When the monomer having a hydrophilic group is an alkali metal salt of the sulfonic acid-containing monomer, the amount added is 3 to 10 mol% based on the total acid component of the water-dispersible polyester composition. It is preferable at the point which balances hot water resistance.

  As another example, there is a method in which a vinyl monomer having a hydrophilic group is graft-polymerized to a copolyester. Examples of the vinyl monomer having a hydrophilic group include a carboxyl group, a hydroxyl group, a sulfonic acid group, an amide group, and the like, and groups that can be changed to a hydrophilic group include an acid anhydride group, a glycidyl group, and a chloro group. Etc. are included. Of these, those having a carboxyl group are preferred. For example, monomers such as acrylic acid, methacrylic acid, maleic acid, and salts thereof. Other vinyl monomers having a hydrophilic group include, for example, epoxy group-containing monomers such as allyl glycidyl ether, monomers containing sulfonic acid groups such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof, or salts thereof, croton Examples thereof include monomers containing a carboxyl group such as acid, itaconic acid, maleic acid, fumaric acid and salts thereof or salts thereof, and monomers containing acid anhydrides such as maleic anhydride and itaconic anhydride. These can be used in combination with other vinyl monomers. Examples of other vinyl monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, and t-butyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and isopropyl. Alkyl methacrylates such as methacrylate, n-butyl methacrylate and t-butyl methacrylate, hydroxy-containing monomers such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N -Methylolacrylamide, N-methylolmethacrylamide, N-methoxymethylacrylamide, N-methyl Amide group-containing monomers such as xymethylmethacrylamide, N, N-dimethylolacrylamide, N-phenylacrylamide, styrene, vinyl methyl ether, vinyl ethyl ether, acrylonitrile, methacrylonitrile, vinylidene chloride, vinyl acetate, vinyl chloride, etc. Among these, one or two or more types can be used for copolymerization.

As a method of grafting a vinyl monomer containing a hydrophilic group onto a resin composition, a known graft polymerization method can be used. A typical example is the following method. For example, a radical polymerization method in which a radical is generated in a main chain polymer substance by light, heat, radiation, etc., and then a vinyl monomer is graft-polymerized, or a cation that generates a cation using a catalyst such as AlCl ₃ or TiCl ₄ There is a polymerization method or an anionic polymerization method in which an anion is generated using metal Na, metal Li, or the like. Another example is a method in which a polymerizable unsaturated double bond is introduced into a main chain resin composition and a vinyl monomer is reacted therewith. Examples of the compound capable of forming an ester bond having a polymerizable unsaturated double bond include fumaric acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, 2,5-norbornene dicarboxylic acid anhydride, and tetrahydrophthalic anhydride. An acid etc. can be mention | raise | lifted. Of these, fumaric acid, maleic acid, and 2,5-norbornene dicarboxylic acid are most preferred.

  The water-dispersible resin composition of the present invention may contain a reactive group different from the hydrophilic group in order to obtain good water-resistant adhesion. The reactive group is a functional group that can chemically bond with a hydroxyl group, carboxyl group, polymerizable unsaturated double bond group, etc. in the resin composition or hydrophilic substance, specifically, an epoxy group, an isocyanate group. Polymerizable unsaturated double bond groups such as vinyl group and allyl group, N, N-bis (alkoxymethyl) amino group, N, N-bis (hydroxymethyl) amino group, N-alkoxymethyl-N-hydroxymethyl Examples thereof include alkylol-modified amino groups such as amino groups and hydroxymethylamino groups or alkyl etherified groups thereof. These reactive groups can be suitably used when they are bonded to the water-dispersed resin composition or when they are bonded to a separately added compound.

  As a method for bonding an epoxy group to a resin composition or a hydrophilic substance, a method of using an epoxy group-containing vinyl monomer such as glycidyl acrylate or glycidyl methacrylate together with the hydrophilic substance for polymerization or grafting, a hydrophilicity that has already been synthesized. For example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a carboxy group obtained by reacting a hydroxy group with phthalic anhydride or trimellitic anhydride, contained in a substance or a polyester containing a phosphonium base. And a method of reacting an epoxy compound containing two or more epoxy groups in one molecule such as a novolak type epoxy resin or a phenol compound-modified epoxy resin so that the epoxy group is in an excessive amount with respect to the carboxy group. .

  Examples of a method for bonding an isocyanate group to a resin composition or a hydrophilic substance include a method in which an isocyanate group-containing monomer such as vinyl isocyanate or allyl isocyanate is used in combination when a hydrophilic substance is polymerized or graft polymerized, or a hydrophilic substance that has already been synthesized. Or an isocyanate compound containing two or more isocyanate groups such as hexamethylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, etc. in one molecule in the resin composition or the like becomes an excessive amount with respect to the functional group in which the isocyanate group reacts with the isocyanate group. The method of making it react is mentioned.

  As a method for bonding a polymerizable unsaturated double bond group to a resin composition or a hydrophilic material, 2-hydroxymethyl acrylate, 2-hydroxy is added to a hydrophilic material or a resin composition to which an isocyanate group is bonded by the above-described method. Examples include a method of reacting hydroxyl group-containing acrylates such as methyl methacrylate.

  A method for adding a compound containing a reactive group as a curing agent separately from a resin composition or a hydrophilic substance is preferable because the coating film physical properties after curing can be prepared depending on the type and amount of the curing agent. one of. A preferable blending amount of the curing agent is 5 to 35% by weight, more preferably 10 to 25% by weight, based on the total of the resin composition and the hydrophilic substance. Curing agents containing alkylol-modified amino groups or alkyl etherated products thereof are alkyl etherified amino formaldehyde resins, curing agents containing epoxy groups are various epoxy compounds, and curing agents containing isocyanate groups are various isocyanates. Examples of the compound and the curing agent containing a polymerizable unsaturated double bond group include various vinyl group-containing monomers.

  The method of laminating the resin layer (II) made of the above water-dispersed resin composition on the resin layer (I) is not limited, and for example, a melt extrusion method, a coating method, or the like can be used. When the coating method is used, it is preferable not to use an organic solvent because an adverse effect on the human body and the environment can be reduced. The thickness of the resin layer B made of the water-dispersed resin composition is preferably controlled to 0.01 to 0.1 μm. This is because if the thickness of the resin layer (II) layer is 0.01 μm or less, sufficient adhesion strength with the metal plate cannot be obtained, and if it exceeds 0.1 μm, the quality is excessive and not economically preferable. When the resin layer B is laminated by the coating method, either a stretched film during film formation (in-line) or a film after film formation (off-line) may be used.

  The polyester film of the present invention needs to be a biaxially stretched film from the viewpoint of obtaining sufficient strength for handling during film formation or processing. Examples of the biaxial stretching method include sequential biaxial stretching and simultaneous biaxial stretching. In the case of sequential biaxial stretching, generally, a method of stretching in the longitudinal direction and then stretching in the transverse direction is adopted, but it may be carried out by a method of stretching in the reverse order. Further, after biaxial stretching, it is preferable to fix the orientation of the polyester by heat treatment, but after biaxial stretching, re-stretching may be performed in the longitudinal direction and / or the width direction before the heat treatment step. Furthermore, the corona discharge treatment or the predetermined coating treatment is not limited at all on one side or both sides of the film before or after the stretching step.

The plane orientation coefficient of the polyester film of the present invention must be less than 0.130. This is because if the plane orientation coefficient is 0.130 or more, the adhesion force when the film is laminated on the metal plate may be insufficient. Further, the density of the polyester film of the present invention needs to be less than 1.385 g / cm ³ . A film with a density of 1.385 cm ³ or more lacks the adhesion between the film and the metal plate and the spreadability of the film. Therefore, the film cannot follow the deformation during can making, and the film peels off from the metal plate or is localized. The film may be torn or cracks may occur. In order to satisfy all the requirements for film formation of biaxially stretched film, handleability during processing, adhesion between the film and the metal plate, canability, etc., the plane orientation coefficient is 0.110 to 0.120, and the density is 1 Particularly preferred is a range of .345 to 1.375 cm ³ .

  The method for laminating the polyester film of the present invention on a metal plate is not particularly limited, and for example, a dry laminating method, a thermal laminating method, or the like can be employed. Specifically, the metal plate is heated to the melting point or higher of the laminate surface of the film, the film is brought into contact with the surface of the metal plate, and passed between the nip rolls in this state. Subsequently, it laminates by making it quench-harden at 10-40 degreeC.

  Moreover, the lamination of the film may be performed only on one side of the metal plate or on both sides. In the case of double-sided lamination, it may be laminated at the same time or sequentially.

  In the present invention, when the film laminated metal plate is applied to a two-piece can, it is preferable to perform a remelt treatment in which heating is performed at a temperature equal to or higher than the melting point of the polyester constituting the film in order to remove the molecular orientation of the polyester after lamination. . Immediately after remelting, it is preferable to carry out forced cooling by using cold water or compressed air. After remelting, crystallization occurs during the process of cooling and solidifying the polyester by slow cooling to the air, etc., and when the polyester undergoes drawing and ironing in the subsequent can manufacturing process, the polyester does not follow the deformation caused by the processing. As a result, it becomes impossible to make cans.

  The degree of molecular orientation by X-ray observation after the remelt treatment is 10% or less, which can be said to be substantially non-oriented. In other words, a biaxially stretched film in which the polyester is in an oriented state is difficult to be plastically deformed or stretched, making it difficult to perform a drawing process for forming the container portion. The delaminating phenomenon of peeling off occurs, tears, or scrapes. On the other hand, if it is substantially non-oriented, it can follow the deformation of the laminated metal plate, so that it can be molded with plastic deformation of the metal like a two-piece can without delaminating or tearing. be able to.

  The film-laminated metal container of the present invention is a metal container formed by appropriately forming the polyester film-laminated metal plate of the present invention, and the shape of the container and the method of forming the metal container are not particularly limited. Specifically, the present invention can be applied not only to a so-called three-piece can in which the top cover is wound and filled with contents, but also to a two-piece can that forms a container portion by drawing a metal plate.

  In the metal container of the present invention, the polyester film of the present invention may be molded so as to be on the inner wall surface side of the metal container, or may be molded so as to be on the outer wall surface side. When the polyester film of the present invention is used for the outer wall surface, a resin coating film containing a pigment or a colorant may be applied in advance in order to conceal the surface of the film to be bonded to the metal.

  In addition, when performing drawing and ironing, if necessary, a lubricant may be applied to the film surface in contact with the punch and die.

  The film-laminated metal container of the present invention may be subjected to printing or the like as necessary, and may be subjected to a remelt treatment again after a can-making process or a printing process.

  In the present invention, a surface-treated steel plate such as tin-free steel, an aluminum plate, an aluminum alloy plate, or a surface-treated aluminum plate or aluminum alloy plate can be used as the metal plate to be used.

  Although the thickness of the polyester film of this invention is not specifically limited, 10-50 micrometers is preferable from the point of a coating effect (rust prevention property), a moldability, and also economical efficiency. If the film thickness is less than 10 μm, the coating effect cannot be obtained, and if it exceeds 50 μm, the film quality is excessive, which is economically undesirable.

  EXAMPLES Hereinafter, although an Example is given and the content and effect of this invention are demonstrated concretely, this invention is not limited to a following example, unless it deviates from the summary.

  Various evaluation methods in the present invention are shown below.

(1) Plane orientation coefficient of film A modified plate analyzer is attached to the eyepiece side of an Abbe refractometer according to JIS K 7142, using NaD line as a light source and methylene iodide as a medium at 25 ° C, The refractive index in the triaxial direction of the thickness is measured. Nx (refractive index in the vertical direction), Ny (refractive index in the horizontal direction), and Nz (refractive index in the thickness direction), and Nx, Ny, and Nz are substituted into the following equation (1) to obtain the plane orientation coefficient (AO). Asked.
AO = (Nx + Ny) / 2−Nz (1)

(2) Density of film It measured at 25 degreeC using the density gradient tube according to JISK7112.

(3) Intrinsic viscosity (IV)
According to JIS K 7367-5, a capillary viscometer (value (dl / g) measured at 25 ° C. using a mixed solvent of phenol / tetrachloroethane-60 / 40 as a solvent using an Ubbelohde clay meter).

(4) Thermal Properties of Polyester After heating and melting the polyester composition at 300 ° C. for 5 minutes, 10 mg of a sample obtained by quenching with liquid nitrogen was used, and 10 using a differential scanning calorimeter (DSC) in a nitrogen stream. The peak temperature of the endothermic peak accompanying melting when the exothermic / endothermic curve (DSC curve) was measured at a temperature elevation rate of ° C./min was defined as the melting point Tm (° C.).

(5) Composition of polyester A polyester resin sample was dissolved in deuterated chloroform containing 15% by weight of trifluoroacetic acid, and 1H-NMR was measured. In the case of a laminated film, the lower layer resin layer was removed with a solvent or the like, and the remaining upper layer sample was dissolved in the same manner, and 1H-NMR was measured. The composition ratio was determined from the integrated intensity of the peaks derived from each component.

(6) Content of ethylene terephthalate cyclic trimer in polyester The polyester is dissolved in hexafluoroisopropyl alcohol / chloroform = 2/3 (V / V), the polyester is precipitated with methanol, and the precipitate is filtered off. The filtrate is evaporated to dryness and the evaporated dry matter is dissolved in dimethylformamide. The obtained solution was developed by a liquid chromatography method, and the content of the ethylene terephthalate cyclic trimer was quantified.

(7) Laminate adhesion The polyester film was pressure-bonded to both sides of a metal plate heated to 240 ° C. between nip rolls, further heated to 275 ° C., and then quenched in water, and the shrinkage width due to peeling of the film end surface was measured and evaluated. . ○ was judged to be practical.
○: Shrinkage width is less than 2 mm Δ: Shrinkage width is 2 mm or more and less than 5 mm ×: Shrinkage width is 5 mm or more

(8) Releasability between can inner surface resin and processing punch After forming the above laminated metal plate into a cup by drawing, 300 cans can be continuously made by redrawing and ironing at a speed of 180 cans / minute, and the upper part of the formed can The degree of buckling occurring in the film was visually observed. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: Buckling has not occurred in the can opening Δ: Buckling has occurred in about 1/3 of the circumference of the can opening ×: Buckling has occurred in more than 1/3 of the circumference of the can opening

(9) Scratch resistance of the outer surface of the can (longitudinal scratch on the outer surface of the can)
After the laminated metal plate is formed into a cup by drawing, 300 cans are continuously produced by redrawing and ironing at a speed of 180 cans / minute, and the degree of scratches on the outer surface of the molded body wall is visually observed. did. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: Scratch not occurred △: Scratch occurred about 1/3 of the outer surface ×: Severe scratch generated more than 1/3 of the outer surface

(12) Tearability A 7 cm square sample was cut out from the above laminated metal plate. This sample was immersed in dilute hydrochloric acid to dissolve and remove a part of the metal plate, and the film was taken out. The film was notched, and both ends thereof were fixed to the upper and lower chucks of a tensile tester and pulled in the vertical direction at a speed of 500 mm / min, and the tearing stress at that time was measured. When the thickness of the measured film is measured and the tear stress converted to a thickness of 25 μm is 0.7 N or less, it can be said that there is substantially no problem with the film cutting ability during continuous canning.

  Next, the kind and content of polyester used for the Example and the comparative example are demonstrated.

(1) A-1: Polyethylene terephthalate / isophthalate (ethylene isophthalate repeating unit 10 mol% (PET-I (10)), (IV = 0.74)
90 parts by weight of terephthalic acid, 10 parts by weight of isophthalic acid, 82 parts by weight of ethylene glycol (ethylene glycol / total acid component) were added to a reactor equipped with an inlet, a thermometer, a pressure gauge, a distillation tube with a rectifying column, and a stirring blade. Amorphous silica particles having a molar ratio of 2.2), 0.05 mol% of germanium oxide as the Ge element, 0.05 mol% of magnesium acetate as the Mg element, and an average particle diameter of 1.3 μm with respect to the acid component 0.23 parts by weight were charged, nitrogen was introduced with stirring, the pressure inside the system was maintained at 0.3 MPa, and the esterification reaction was performed while distilling off the water generated at a temperature of 230 ° C. to 250 ° C. outside the system. . After completion of the reaction, 0.04 mol% of trimethyl phosphate as P amount was added at 250 ° C, and the pressure was gradually reduced while the temperature was raised. Obtained. Subsequently, this polyester was heat-treated at 200 ° C. under a vacuum of 1.0 hPa for 12 hours to obtain polyester A-1 (PET-I (10)). The polyester obtained had an intrinsic viscosity of 0.74 (dl / g) and an ethylene terephthalate cyclic trimer of 0.5% by weight.

(2) A-2: Polyethylene terephthalate (PET) (IV = 0.75)
82 parts by weight of ethylene glycol (ethylene glycol / terephthalic acid molar ratio = 2) with respect to 100 parts by weight of terephthalic acid in a reactor equipped with an inlet, a thermometer, a pressure gauge, a distillation tube with a rectifying column, and a stirring blade .2) 0.05 mol% of germanium oxide as the Ge element, 0.05 mol% of magnesium acetate as the Mg element, and 0.23 weight of amorphous silica particles having an average particle diameter of 1.3 μm with respect to the acid component Part was charged, nitrogen was introduced with stirring, the pressure inside the system was kept at 0.3 MPa, and the esterification reaction was carried out while distilling out water generated at a temperature of 230 ° C. to 250 ° C. outside the system. After completion of the reaction, 0.04 mol% of trimethyl phosphate as P amount was added at 250 ° C, and the pressure was gradually reduced while the temperature was raised. Obtained. Subsequently, this polyester was heat-treated at 220 ° C. under a vacuum of 1.0 hPa for 12 hours to obtain polyester A-2 (PET). The intrinsic viscosity of the obtained polyester was 0.75 (dl / g), and the ethylene terephthalate cyclic trimer was 0.5% by weight.

(3) B: Polytetramethylene terephthalate-polytetramethylene oxide block copolymerized polyester (IV = 0.75)
In a reaction apparatus equipped with an inlet, a thermometer, a pressure gauge, a distillation tube with a rectifying column, and a stirring blade, 75 parts by weight of 1,4-butanediol, polytetramethylene glycol with respect to 100 parts by weight of dimethyl terephthalate (Average molecular weight 1000) 75 parts by weight and normal butyl titanate 0.05 parts by weight were charged, and transesterification was carried out while distilling methanol produced at 190 ° C. to 230 ° C. out of the system. After completion of the reaction, 0.05 part by weight of tetranormal butyl titanate and 0.025 part by weight of phosphoric acid were added, and a polycondensation reaction was performed at 250 ° C. under reduced pressure (1.0 hPa or less). Polytetramethylene terephthalate-polytetramethylene oxide block copolymer, polytetramethylene oxide ratio 40% by weight, intrinsic viscosity 0.75) were used.

(4) C-1: Polyester containing 1% by weight of wax With respect to 99 parts by weight of polyester A-1, 1 part by weight of polyethylene wax (manufactured by Mitsui Chemicals, Inc .: high wax) is melt-kneaded with a twin screw extruder. Thus, a polyester resin (C-1) containing 1% wax was obtained.

(5) C-2: Polyester containing 5% by weight of antioxidant 5 parts by weight of a phenolic antioxidant (Irganox 1010, manufactured by Ciba Geigy) to 95 parts by weight of polyester A-1 in a twin screw extruder And kneaded to obtain a 5% antioxidant-containing polyester resin (C-2).

Example 1
A-1 / B / C-1 = 90/5/5 (% by weight) as a raw material was dried at 100 ° C. for 24 hours, melted at 270 ° C. using a single screw extruder, and then layered from a T die. And extruded on a cooling roll to obtain an unstretched sheet. The unstretched sheet was stretched 3.3 times in the machine direction at a preheating temperature of 80 ° C. and a stretching temperature of 100 ° C., and further stretched by 3.7 times in the transverse direction at a preheating temperature of 80 ° C. and a stretching temperature of 100 ° C. Two types of polyester films (200 m roll film) having a thickness of 25 μm and 16 μm were obtained by heat treatment at 8 ° C. for 8 seconds. The amount of tetramethylene oxide derived from the polytetramethylene glycol component in this film was 5.2 mol% with respect to the acid component (total amount of terephthalic acid and isophthalic acid).

  This film was pressure-bonded between nip rolls on both sides of a 3004 series aluminum alloy plate (thickness 0.26 mm) heated to 240 ° C., further heated to 275 ° C., and then rapidly cooled in water to obtain a laminated metal plate.

  After applying the forming lubricant to the laminated metal plate thus obtained, the laminate was heated and drawn at a plate temperature of 70 ° C. so that the 16 μm film side became the outer surface side. Subsequently, the temperature of the obtained cup was set to 40 ° C., and redrawing and ironing were performed at a mold temperature of 80 ° C. to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the composition, melting point, density, surface orientation coefficient, lami adhesion, can-making property (releasability of can inner film and punch and degree of scratching on can outer film), and tearability of polyester film. . The film of this example was excellent in laminar adhesion, and the film laminate plate was excellent in can-making property and tearability.

Example 2
An unstretched sheet was prepared by the same method as in Example 1 except that A-1 / A-2 / B / C-1 = 45/45/5/5 (% by weight) was used as a raw material, and further carried out. In the same manner as in Example 1, two kinds of polyester films (200 m roll film) having thicknesses of 25 μm and 16 μm were obtained through a stretching process and a heat treatment process. The amount of tetramethylene oxide derived from the polytetramethylene glycol component in this film was 5.2 mol% with respect to the acid component (total amount of terephthalic acid and isophthalic acid).

  Using this film, a laminated metal plate and a 350 ml size seamless can were obtained in the same manner as in Example 1.

  Tables 1 and 2 show the composition, melting point, density, surface orientation coefficient, lami adhesion, can-making property (releasability of can inner film and punch and degree of scratching on can outer film), and tearability of polyester film. . The film of this example was excellent in laminar adhesion, and the film laminate plate was excellent in can-making property and tearability.

Example 3
An unstretched sheet was prepared in the same manner as in Example 1 except that A-1 / B / C-1 = 93/2/5 (% by weight) was used as a raw material, and further stretched in the same manner as in Example 1. Through the steps and the heat treatment step, two kinds of polyester films (200 m roll film) having thicknesses of 25 μm and 16 μm were obtained. The amount of tetramethylene oxide derived from the polytetramethylene glycol component in this film was 2.2 mol% with respect to the acid component (total amount of terephthalic acid and isophthalic acid).

  Using this film, a laminated metal plate and a 350 ml size seamless can were obtained in the same manner as in Example 1.

  Tables 1 and 2 show the composition, melting point, density, surface orientation coefficient, lami adhesion, can-making property (releasability of can inner film and punch and degree of scratching on can outer film), and tearability of polyester film. . The film of this example was excellent in laminar adhesion, and the film laminate plate was excellent in can-making property and tearability.

Example 4
An unstretched sheet was prepared in the same manner as in Example 1 except that A-1 / B / C-1 / C-2 = 88/5/5/2 (% by weight) was used as a raw material, and further implemented. In the same manner as in Example 1, two types of polyester films (200 m roll film) having a thickness of 25 μm and 16 μm were obtained through a stretching process and a heat treatment process. The amount of tetramethylene oxide derived from the polytetramethylene glycol component in this film was 5.2 mol% with respect to the acid component (total amount of terephthalic acid and isophthalic acid).

  Using this film, a laminated metal plate and a 350 ml size seamless can were obtained in the same manner as in Example 1.

  Tables 1 and 2 show the composition, melting point, density, surface orientation coefficient, lami adhesion, can-making property (releasability of can inner film and punch and degree of scratching on can outer film), and tearability of polyester film. . The film of this example was excellent in laminar adhesion, and the film laminate plate was excellent in can-making property and tearability.

Comparative Example 1
An unstretched sheet was prepared in the same manner as in Example 1 except that A-2 / B / C-1 = 90/5/5 (% by weight) was used as a raw material. The obtained unstretched sheet was stretched 3.3 times in the machine direction at a preheating temperature of 80 ° C. and a stretching temperature of 100 ° C., and further stretched by 3.7 times in the transverse direction at a preheating temperature of 80 ° C. and a stretching temperature of 100 ° C. Heat treatment was performed at 210 ° C. for 8 seconds to obtain two kinds of polyester films (200 m roll film) having a thickness of 25 μm and 16 μm. The amount of tetramethylene oxide derived from the polytetramethylene glycol component in this film was 5.2 mol% with respect to the acid component (total amount of terephthalic acid and isophthalic acid).

  Using this film, a laminated metal plate and a 350 ml size seamless can were prepared in the same manner as in Example 1. However, when the film of this comparative example was laminated on the metal plate, the adhesion was weak, and when the film was remelted, Therefore, the temperature of the metal plate was raised to 250 ° C. to obtain a laminated metal plate. In addition, when a laminated metal plate was made, a part of the can inner film was peeled off from the metal plate, and a crack was generated on the outer surface film of the can, so the can making speed was reduced to 60 cans / minute to obtain a seamless can. It was.

  Tables 1 and 2 show the composition, melting point, density, surface orientation coefficient, lami adhesion, can-making property (releasability of can inner film and punch and degree of scratching on can outer film), and tearability of polyester film. . Since the film of this comparative example was inferior in lamellar adhesiveness and the film laminated board was inferior in can-making property, it is not a preferable method.

Comparative Example 2
In Example 2, the obtained unstretched sheet was stretched 3.5 times in the machine direction at a preheating temperature of 80 ° C. and a stretching temperature of 100 ° C., and further in the transverse direction at a preheating temperature of 80 ° C. and a stretching temperature of 100 ° C. After stretching 0 times, heat treatment was performed at 150 ° C. for 8 seconds to obtain two kinds of polyester films (200 m roll film) having a thickness of 25 μm and 16 μm.

  Using this film, a laminated metal plate and a 350 ml size seamless can were obtained in the same manner as in Example 1. However, when the film of this comparative example was laminated on the metal plate, the adhesion was weak, and when the film was remelted, Therefore, the temperature of the metal plate was raised to 250 ° C. to obtain a laminated metal plate.

  Tables 1 and 2 show the composition, melting point, density, surface orientation coefficient, lami adhesion, can-making property (releasability of can inner film and punch and degree of scratching on can outer film), and tearability of polyester film. . The film laminate plate of this comparative example was excellent in canability and tearability, but is not a preferred method because of poor adhesion during lamination.

Comparative Example 3
Except that A-1 / B = 95/5 (% by weight) was used as a raw material, an unstretched sheet was prepared by the same method as in Example 1, and further subjected to a stretching process and a heat treatment process as in Example 1. Two types of polyester films (200 m roll film) having a thickness of 25 μm and 16 μm were obtained. The amount of tetramethylene oxide derived from the polytetramethylene glycol component in this film was 5.2 mol% with respect to the acid component (total amount of terephthalic acid and isophthalic acid).

  Using this film, a laminated metal plate and a seamless can of 350 ml size were produced in the same manner as in Example 1. However, when the laminated metal plate was made, the releasability between the can inner film and the processed punch was poor, and the can Since a part of the bottom was deformed and a fine crack was generated on the film on the outer surface of the can, the can-making speed was reduced to 60 cans / minute to obtain a seamless can.

  Tables 1 and 2 show the composition, melting point, density, surface orientation coefficient, lami adhesion, can-making property (releasability of can inner film and punch and degree of scratching on can outer film), and tearability of polyester film. . Although the film of this comparative example was excellent in adhesion and tearability at the time of lamination, the film laminate plate was not preferable because it was inferior in can-making property (particularly, punch adhesiveness on the inner surface).

Comparative Example 4
An unstretched sheet is prepared by the same method as in Example 1 except that A-1 / C-1 = 95/5 (% by weight) is used as a raw material. Further, as in Example 1, a stretching process and a heat treatment process are performed. Then, two types of polyester films (200 m roll film) with thicknesses of 25 μm and 16 μm were obtained. The amount of tetramethylene oxide derived from the polytetramethylene glycol component in this film was 0 mol% with respect to the acid component (total amount of terephthalic acid and isophthalic acid).

  Using this film, a laminated metal plate and a 350 ml size seamless can were produced in the same manner as in Example 1.

  Tables 1 and 2 show the composition, melting point, density, surface orientation coefficient, lami adhesion, can-making property (releasability of can inner film and punch and degree of scratching on can outer film), and tearability of polyester film. . Although the film of this comparative example was excellent in the adhesion at the time of lamination, the film laminate plate was not preferable because it was slightly inferior in can-making properties and inferior in tearing properties.

Comparative Example 5
An unstretched sheet was prepared by the same method as in Example 1 except that A-1 / B / C-1 = 75/20/5 (% by weight) was used as a raw material, and further stretched in the same manner as in Example 1. Two types of polyester films (200 m roll film) having a thickness of 25 μm and 16 μm were obtained through the steps and the heat treatment step. The amount of tetramethylene oxide derived from the polytetramethylene glycol component in this film was 23.0 mol% with respect to the acid component (total amount of terephthalic acid and isophthalic acid).

  Using this film, a laminated metal plate and a 350 ml size seamless can were produced in the same manner as in Example 1. However, when the film of this comparative example was laminated, wrinkles were generated on the film. Moreover, when the laminated metal plate was made, the releasability between the can inner surface film and the processing punch was poor, the part of the can bottom was deformed, and the can outer surface film was cracked. / Min. To obtain a seamless can.

  Tables 1 and 2 show the composition, melting point, density, surface orientation coefficient, lami adhesion, can-making property (releasability of can inner film and punch and degree of scratching on can outer film), and tearability of polyester film. . Although the film of this comparative example was excellent in the adhesiveness at the time of lamination, it was inferior in the handleability at the time of lamination. Moreover, since the film laminate board was also inferior in can-making property, it is not a preferable method.

  The laminated polyester film of the present invention is excellent in adhesion to a laminate with a metal plate. Further, the obtained film laminate metal plate has a can-making property (particularly, the separation of a can inner film and a processing punch during can-making under severe conditions). Polyester film used for the purpose of preventing corrosion of metal containers such as soft drinks, beer, canned foods, etc., and a film laminate obtained by laminating the film on a metal plate It can be said that it is extremely useful as a metal container obtained by molding a metal plate and the film-laminated metal plate.

Claims (4)

It consists of a polyester composition having a melting point of 220 to 250 ° C. mainly composed of a copolymer polyester composed of an ethylene terephthalate component and an ethylene isophthalate component, and has a density of less than 1.385 g / cm ³ and a plane orientation coefficient of less than 0.130. It is a biaxially oriented polyester film, and the polyester composition has a polyoxyalkylene glycol component in which the repetition of alkylene oxide units having 2 or more carbon atoms is 3 or more, and the carbon number derived from the polyoxyalkylene glycol component is 2 to 20 mol% of the total acid component of the polyester composition as two or more alkylene oxide units, and further 0.01 to 0.15 wt% of a wax. Polyester film for laminating.   A polyester film for laminating a metal plate, wherein the polyester composition constituting the polyester film according to claim 1 contains a polyalkylene terephthalate-polytetramethylene oxide block copolymer.   A laminated metal plate obtained by laminating the polyester film according to claim 1 on at least one surface of a metal plate.   A metal container formed by molding the laminated metal plate according to claim 3.