JP2009078542A - Drawing and ironing can coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drawing and ironing can coating film which can be used as a laminate film for two-piece can, is excellent in molding processing in can manufacturing and is excellent in impact resistance upon low-temperature storage and upon transferring, to provide a film laminate metal plate and ironing can coating film, and to provide a film laminate metal container. <P>SOLUTION: The drawing and ironing can coating film comprises a polyester-based resin film provided with a cover layer made of a water-dispersion type polymer acrylic resin, and a wax is contained by 500 ppm or more in the film comprising a polyester-based resin prepared by compounding a polyester (A) having ethylene terephthalate as a main constitutional component, of 10 to 90 wt.% and a crystalline polyester (B) different from the polyester (A), of 90 to 10 wt.%, wherein the ratio w/h of half band width w (°C) of recrystallization peak (Tc2) to height h (mW) upon temperature falling in a differential scanning calorimeter (DSC) is 2.30 (°C/mW) or less and, further, a coat layer thickness after drying of the water-dispersion type copolymerization polyester resin lies in the range of 500 nm to 5,000 nm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermoplastic resin film suitable for a resin-coated metal plate. In particular, the present invention relates to a thermoplastic resin film suitably used for surface coating of a drawn iron can. More specifically, the present invention relates to a film for covering a drawn iron can that is excellent in can manufacturing process and impact resistance such as drawing and ironing.

  For food cans, in addition to the so-called three-piece cans, in which a lid is attached to the upper and lower openings of a metal cylinder formed by cylindrical molding of a metal plate, a metal plate is deep-drawn to form a container part, There is a so-called two-piece can formed by winding a lid on the upper surface opening of the container.

  In the case of a three-piece can, the film-laminated metal plate is only formed into a cylindrical shape, but in the case of a two-piece can, the film-laminated metal plate is formed by drawing and ironing. Therefore, in order to be applicable to a two-piece can, it is necessary to have good formability of being formed following the formation of a metal plate and to have excellent adhesion to the metal plate. When the formability is insufficient or the film adheres poorly to the metal plate, a so-called delaminating phenomenon occurs in which the film is peeled off from the metal plate, or when the container part of the two-piece can is produced. This is because the film is torn.

  Furthermore, in the drawing process, the film laminate metal plate is processed into a container shape while repeating the lowering and raising of the punch. Therefore, in the case of a film laminated on the inner wall surface of the container, the release property from the punch, as well as the container In the case of an outer wall surface, releasability from the die is required.

Therefore, a film comprising a polyester (I) mainly composed of polybutylene terephthalate, a polyester (II) mainly composed of polyethylene terephthalate, and a low molecular weight polymer (III), and a mass ratio of the polyesters (I) and (II) ( I) / (II) is 80-40 / 20-60, and the film has a melting point of polyester (I) at 200 ° C. to 223 ° C. and a melting point of polyester (II) at 230 ° C. to 256 ° C. The low molecular weight polymer (III) is substantially incompatible with the polyesters (I) and (II), the number average molecular weight is 1000 to 8000, the melting point is 100 ° C to 135 ° C, A metal plate laminating film characterized in that the content is 0.01 to 1.0% by mass has been proposed (for example, patent document). Reference.)
JP 2005-68360 A

  However, this film has a problem that the impact resistance is not good.

  The object of the present invention has been made in view of such circumstances, and can be applied as a laminate film for so-called two-piece cans. An object of the present invention is to provide an excellent squeezing and ironing can coating film, a film laminated metal plate and a film laminated metal container.

  The film for covering a squeezed iron can according to the present invention that has achieved the above object is a polyester resin film in which a coating layer made of a polymer acrylic resin is provided on a base material layer made of a polyester resin, and is mainly composed of ethylene terephthalate. 500 ppm or more of wax in a film comprising a polyester resin composition containing 10 to 90% by weight of polyester (A) as a constituent component and 90 to 10% by weight of crystalline polyester (B) different from polyester (A) The ratio w / h of the half-value width w (° C.) and the height h (mW) of the recrystallization peak (Tc2) at the time of cooling in the differential scanning calorimeter (DSC) is 2.30 (° C. / MW) or less, and the coating thickness of the polymer acrylic resin is in the range of 500 nm to 5000 nm. It is.

  In this case, the coating layer is a water-dispersible polymer acrylic resin or a water-dispersible polymer acrylic resin and a water-soluble or water-dispersible epoxy compound, melamine resin, isocyanate compound, silane coupling agent, It is preferable to contain one or more cross-linking agents selected from polyethyleneimine and polyvinyl alcohol.

  Furthermore, in this case, it is preferable that the polymer acrylic resin has a Tg of 40 ° C. or higher and 70 ° C. or lower.

Furthermore, in this case, it is preferable that the coating layer is provided by a coating process.
Furthermore, in this case, it is preferable that the reduced viscosity of the polyester resin composition is 0.80 or more.

  Furthermore, in this case, a squeezing and ironing metal plate characterized in that the film is coated on the metal plate is useful.

  Furthermore, in this case, it is preferable to remelt the film of the coated metal plate.

  Furthermore, in this case, a squeezed and ironed can characterized in that the squeezed and ironed metal plate can be made is useful.

  When used as a laminate film for a two-piece can, the polyester film for squeezing and ironing can coating of the present invention has excellent adhesion to metal and molding processability, and excellent impact resistance when subjected to impact at low temperatures. .

Hereinafter, the present invention will be described in more detail.
Polyester (A) mainly comprising ethylene terephthalate in the present invention (hereinafter, polyester (A) refers to a polyester in which 80 mol% or more of the polyester component is ethylene terephthalate, preferably 90 mol% or more is ethylene terephthalate. The polyester which is.

  Here, the polyester is a polymer composed of a dicarboxylic acid component and a glycol component, and a dicarboxylic acid component other than terephthalic acid, such as naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodiumsulfoisophthalate. Aromatic dicarboxylic acids such as acid and phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids, p -A dicarboxylic acid component arbitrarily selected from oxycarboxylic acids such as oxybenzoic acid may be copolymerized. In addition, glycol components other than ethylene glycol, for example, aliphatic glycols such as trimethylene glycol, butanediol, pentanediol, hexanediol and neopentylglycol, alicyclic glycols such as cyclohexanedimethanol, bisphenol A, bisphenol S and Uno Fragrance A glycol component arbitrarily selected from group glycols and the like may be copolymerized. Two or more kinds of these dicarboxylic acid components and glycol components may be used in combination. The melting point of the polyester A is preferably 240 ° C to 265 ° C.

  The reduced viscosity of the polyester A is preferably 0.55 to 0.90, more preferably 0.58 to 0.80. If the reduced viscosity is smaller than this range, it becomes difficult to obtain a mechanical strength film that can be used practically, and even if it exceeds this range, the mechanical strength effect does not change, and this is disadvantageous in terms of cost. It is not preferable.

  The crystalline polyester (B) in the present invention (hereinafter referred to as polyester B) is polybutylene terephthalate (PBT) polyester, polyethylene-2,6-naphthalate (PEN) polyester, polytrimethylene terephthalate (PTT) polyester, poly One or two or more polyesters selected from hexamethylene terephthalate (PHT) polyester and polypentamethylene terephthalate (PPT) polyester, preferably polybutylene terephthalate (PBT) polyester, polyethylene-2, 6-Naphthalate (PEN) polyester, polytrimethylene terephthalate (PTT) polyester, polyhexamethylene terephthalate (PHT) polyester or polypentamethylene It is a phthalate (PPT) polyester. Here, the polyester is a polymer composed of a dicarboxylic acid component and a glycol component. These crystalline polyesters are all homopolyesters (that is, polybutylene terephthalate (PBT), polyethylene-2,6-naphthalate (PEN), polytrimethylene terephthalate (PTT), polyhexamethylene terephthalate (PHT), polypenta. Methylene terephthalate (PPT)) is preferable, but it may be a copolyester obtained by further copolymerizing the homopolyester with other dicarboxylic acid component and / or glycol component. Examples of the dicarboxylic acid component as the copolymer component include diphenyl dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, 5-sodium sulfoisophthalic acid, phthalic acid and other aromatic dicarboxylic acids, oxalic acid, and succinic acid. Any dicarboxylic acid among aliphatic dicarboxylic acids such as adipic acid, sebacic acid, dimer acid, maleic acid and fumaric acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, oxycarboxylic acids such as p-oxybenzoic acid, etc. Examples of the glycol component include aliphatic glycols such as ethylene glycol, trimethylene glycol, butanediol, pentanediol, hexanediol and neopentylglycol, alicyclic glycols such as cyclohexanedimethanol, and bisphenol. Any glycol component is mentioned to be selected from among such aromatic glycols such as bisphenol S, these dicarboxylic acid components, the glycol component may be used in combination of two or more thereof. In addition, the copolymerization amount of these dicarboxylic acid components and / or glycol components is in a range that does not impair the high crystallinity of the polyester, and is usually 20 mol% or less based on the entire polyester.

  The melting point of polybutylene terephthalate (PBT) polyester is preferably 215 to 235 ° C., and the melting point of polyethylene-2,6-naphthalate (PEN) polyester is preferably 260 to 275 ° C., and the melting point of polytrimethylene terephthalate (PTT) polyester The melting point is preferably 230 to 245 ° C, the melting point of the polyhexamethylene terephthalate (PHT) polyester is preferably 150 to 170 ° C, and the melting point of the polypentamethylene terephthalate (PPT) polyester is preferably 130 to 150 ° C.

  In the present invention, the crystalline polyester (B) is polybutylene terephthalate (PBT) polyester, polyethylene-2,6-naphthalate (PEN) polyester, polytrimethylene terephthalate (PTT) polyester, polyhexamethylene terephthalate. (PHT) polyester and polypentamethylene terephthalate (PPT) polyester.

  In the present invention, the reduced viscosity of the crystalline polyester B is preferably 0.80 to 2.20, more preferably 0.85 to 1.50. If the reduced viscosity is less than this range, it is difficult to obtain a film having mechanical strength that can be used practically, and even if it exceeds this range, the effect of mechanical strength does not change, which is disadvantageous in cost. It is not preferable.

  In the polyester film of the present invention, the content of cyclic trimer including ethylene terephthalate cyclic trimer is preferably 0.7% by weight or less. This is to suppress the precipitation of oligomers in the film. As will be described later, when a two-piece can is manufactured, the laminated film of the present invention is subjected to a drawing process after undergoing a remelt treatment for forming non-oriented polyester. In non-oriented polyester, oligomers are more likely to precipitate than in oriented polyester. Therefore, when the cyclic trimer is contained in excess of 0.7% by weight, for example, when a two-piece can obtained by laminating this film is filled with a beverage and subjected to a heat treatment such as a retort treatment, This is because a large amount of the oligomer is eluted from the polyester, and further, this oligomer migrates to the food and adversely affects the taste and flavor of the food.

The method for setting the content of the cyclic trimer including the ethylene terephthalate cyclic trimer in the polyester to 0.7% by weight or less is not particularly limited. [1] After forming the laminated film, water or Examples thereof include a method of extracting and removing the cyclic trimer with an organic solvent, and [2] a method of forming a polyester film using a polyester having a small amount of the cyclic trimer. Of these, the method [2] is more economical and preferable.
In the above method [2], the method for producing a polyester having a low cyclic trimer content is not limited, and the solid phase polymerization method; after the polymerization, by heat treatment under reduced pressure or by extraction with water or an organic solvent, And a method for extracting and removing the polymer; and a method combining these methods. In particular, after producing a polyester having a low cyclic trimer content by solid phase polymerization, the method of extracting the obtained polyester with water to further reduce the cyclic trimer is the cyclic trimer in the film forming step. This is most preferable because the amount of body produced is suppressed.

  In the polyester film of the present invention, the blending ratio (A / B) of the polyester (A) and the polyester (B) is generally 10 to 90% by weight / 90 to 10% by weight, preferably 10 to 70% by weight / 90 to 30% by weight, more preferably 35 to 65% by weight / 65 to 35% by weight. If the amount of polyester A exceeds the specified range and the amount of polyester A is small (the amount of polyester B is small), the film forming processability deteriorates. As a result, the film is easily damaged, and when the amount of polyester B is large (when the amount of polyester A is small), the film is sufficiently whitened when the film is cooled to a temperature close to or above its melting point. It becomes impossible to suppress.

  FIG. 1 is a simplified chart showing a recrystallization peak of a crystalline polyester film when the temperature is lowered by a differential scanning calorimeter (DSC). In this figure, when the height from the base line L to the peak top t of the recrystallization peak 1 is h (mW) and the temperature width at the height h / 2, that is, the half width is w (° C.), A ratio w / h (° C./mW) between the value width w and the height h is defined.

The speed of crystallization in the recrystallization process when the polyester film is cooled can be known from the value of the ratio w / h of the half width w and the height h of the recrystallization peak defined as described above. It is considered that the smaller the value of the ratio w / h, the faster the crystallization rate. It is considered that the smaller the value of the ratio w / h is, the more moderately and coarsely dispersed the polyester resins (A) and (B) are in the film system, and the faster the crystallization rate of the film.

  In the polyester film of the present invention, when the value of the ratio w / h is 2.30 (° C./mW) or less, the crystallization rate of the film during the cooling process when the temperature is lowered from around the melting point of the film or from above the melting point. Since it is fast, microcrystals that are small enough not to contribute to the scattering of visible light can be rapidly and abundantly formed inside the film, so that the film is not whitened while maintaining the processing characteristics. On the other hand, when the value of the ratio w / h is larger than 2.30 (° C./mW), since the film crystallization rate in the cooling process at the time of cooling is slow, the crystallites scatter visible light. It is thought that the film will be whitened.

  In the polyester film of the present invention, the value of the ratio w / h of the recrystallization peak at the time of cooling is preferably 2.30 (° C./mW), more preferably 2.10 ° C./mW or less, and 2.00 or less. Is more preferable. The polyester film having such a preferable ratio w / h exhibits more preferable whitening resistance. The lower limit of the ratio w / h is not particularly defined, but is generally about 0.30 ° C./mW.

  In the present invention, the polyester film having a half-value width of the recrystallization peak at the time of temperature reduction of 2.30 or less in the differential scanning calorimeter (DSC) is the polyester (A) in the polyester mixture in the film production process. This can be achieved by adjusting the dispersion state of the polyester (B).

  In the present invention, half-width control is achieved by maintaining the crystallinity independence of polyester (A) and polyester (B). For example, when producing a blend film of PET (melting point 255 ° C.) and PBT (melting point 220 ° C.) with a single extruder having a single or twin screw, the temperature of the extruder corresponds to the melting point of PET with a high melting point. Therefore, it is necessary to set the melting point or higher. In this case, the decomposition of PBT proceeds more rapidly, and the molecular weight is lowered by the heat of the extruder, so that the compatibility with PET becomes higher and the dispersion proceeds more uniformly and is finely dispersed. Accordingly, both of them are easily copolymerized (transesterification) in the process of melting and mixing, and each crystallinity is impaired and the influence of each other is strongly influenced without copolymerization. It is considered that the independence of crystallinity becomes difficult to maintain, the crystallization speed of the film becomes slow, and coarse spherulites that cause whitening are likely to occur.

  In order to suppress these transesterifications, it is achieved by containing additives such as heat stabilizers and antioxidants and by controlling the resin temperature during melt extrusion.

  Various means are known as means for suppressing side reactions such as transesterification in a film composition containing polyethylene terephthalate-based polyester and other crystalline polyesters, but they are applied in the field of industrial film production. For this purpose, a method of adding an organophosphorus compound (catalyst) is preferred from the viewpoint of inhibiting copolymerization of the polyester (A) and the polyester (B). Thus, the effect of suppressing the transesterification reaction can be enhanced.

  In the present invention, the organophosphorus compound (catalyst) preferably has a melting point of 200 ° C. or higher in view of stability in the extruder (mixer stand). For example, dimethyl methylphosphonate, diphenyl methylphosphonate, phenyl Dimethyl phosphonate, diethyl phenylphosphonate, diphenyl phenylphosphonate, dimethyl phosphophosphonate, diethyl benzylphosphonate, diphenylphosphinic acid, methyl diphenylphosphinate, phenyl diphenylphosphinate, phenylphosphinic acid, methyl phenylphosphinate, diphenylphosphinic acid Phenyl, diphenylphosphine oxide, methyldiphenylphosphine oxide, triphenylphosphine oxide and the like can be raised, and among these, those having a molecular weight of 200 or more are particularly preferable. These organic phosphorus compounds can be used alone or in combination of two or more, and the amount added depends on the type of the phosphorus compound, but is generally 0.01 to 0.00 with respect to the total amount of the polyester to be blended. About 3% by weight is preferred. Furthermore, the range of 0.1 to 0.3 weight% is preferable. The organophosphorus compound is preferably premixed with the resin in advance, and more preferably premixed with at least the polyester A chip.

  When the polyester film is used for food applications such as beverage cans, the organophosphorus compound needs to be used in a compound and amount that meet the standards of the FDA (Food and Drug Administration), the Sanitation Council for Polyolefins, and the like.

  The reduced viscosity (ηsp / c) of the polyester film of the present invention is preferably 0.80 or more, more preferably 0.85 or more, still more preferably 0.90 or more, and most preferably 0.95 or more. If it is less than 0.80, the hardness of the film after lamination on the metal plate is insufficient, and it becomes easy to be damaged during processing, and the aluminum or steel plate may be deformed or partially broken during can making. When the reduced viscosity satisfies such a numerical value and the recrystallization peak temperature (Tc2) satisfies the above numerical value, the scratch resistance of the film is further improved.

  In the polyester film of the present invention, it is preferable to use inert inorganic particles, crosslinked polymer particles, or the like as a lubricant. As the inert particles, silica, alumina, kaolin, clay, titanium oxide, calcium phosphate, calcium carbonate, lithium fluoride, barium sulfate, carbon black and the like are preferable.

  Cross-linked polymer particles include acrylic monomers such as acrylic acid, methacrylic acid, acrylic esters and methacrylic esters, styrene monomers such as styrene and alkyl-substituted styrene, and divinylbenzene and divinyl sulfone. , Copolymers with crosslinkable monomers such as ethylene glycol dimethacrylate, trimethylolpropane trimethyl acrylate, pentaerythritol tetramethyl acrylate; melamine resins; benzoguanamine resins; phenol resins; silicon-containing resins it can.

  The average particle size of the particulate lubricant is preferably 1 to 3 μm. This is because if it is less than 1 μm, the effect of improving punch releasability cannot be exhibited. Conversely, if it exceeds 3 μm, the effect of improving punch release properties is saturated, while slipping of the lubricant is likely to occur due to wear, or film breakage may occur during lamination with a metal plate.

  The amount of the lubricant is preferably added in the range of 0.01 to 2% by weight. This is because a lubricant amount of 0.01% by weight or more is preferable in order to ensure release from the punch during drawing. On the other hand, even if it contains an amount exceeding 2% by weight, the effect of releasability does not change and only the cost becomes disadvantageous.

  In addition, it is preferable to use wax because the effect of slipperiness during can making can be obtained with a minimum amount. When using wax, it is a preferred embodiment that it is added in the range of 500 ppm to 2000 ppm. Furthermore, the range of 800-2000 ppm is preferable. If it is less than 500 ppm, the dynamic friction coefficient with the film surface using a steel ball in a 50 ° C. environment as a slider does not become 0.30 or less, and molding processability cannot be obtained. This is because the effect of this does not change and is disadvantageous in terms of cost.

Examples of the wax include synthetic waxes such as polyolefin wax and polyester wax, and natural waxes such as carnauba wax.
At this time, the molecular weight of the wax is preferably 10,000 or less.

  In addition to the above compounds, the polyester film may include inorganic fine particles, incompatible thermoplastic resins, antioxidants, thermal stabilizers, ultraviolet absorbers, plasticizers, pigments, antistatic agents, as necessary. Additives such as lubricants and crystal nucleating agents may be included. It is a preferred embodiment that the antioxidant is contained in an amount of 0.01 to 1% by weight in the polyester.

Next, the polymer acrylic resin will be described. The polymer acrylic resin in the present invention preferably has a Tg of 40 ° C. or higher and 70 ° C. or lower. When Tg is low, the strength of the coating layer is not sufficient, and when Tg is high, impact resistance is not sufficient.
The coating layer thickness is preferably controlled to a thickness of 500 nm to 5000 nm. Furthermore, the range of 1000-5000 nm is preferable.
When the thickness of the coating layer provided on the base material layer is less than 500 nm, impact resistance cannot be imparted, and the coating layer is cracked when subjected to impact at low temperature, and corrosion of the can occurs, which is not preferable in terms of quality. Further, even if the coating layer is provided with a thickness exceeding 5000 nm, the impact resistance effect does not change, which is disadvantageous in terms of cost.
The coating layer made of a polymer acrylic resin is preferably provided by coating the base material layer.
Regarding this coating treatment, either a stretched film during film formation (in-line) or a film after film formation (off-line) may be used.
In order to use the polymer acrylic resin for the coating treatment, the polymer acrylic resin is preferably a water-dispersed polymer.
In the coating treatment, it is desirable to perform a heat treatment at a temperature of 140 to 180 ° C. for 5 to 20 seconds after applying an aqueous dispersion of a polymer acrylic resin to the base material layer.

  The water-dispersible polymer acrylic resin is composed of a water-dispersible acrylic emulsion of at least one alkyl acrylate.

  As a preferable form of the water-dispersible polymer acrylic resin of the present invention, the at least one alkyl acrylate is methyl methacrylate, ethyl acrylate, (1) methacrylamide and esterified triazine, and (2) N-methylolacrylamide. There may be mentioned at least one selected from the group.

  In the present invention, it is a more preferable embodiment to add a crosslinking agent such as an epoxy compound, a melamine resin, an isocyanate compound, a silane coupling agent, polyethyleneimine, and polyvinyl alcohol. In the present invention, it is necessary to use one or more selected from these in combination. The cross-linking agent is also preferably water-soluble or water-dispersible in order to be applied to a polyester film without using an organic solvent.

  Examples of the epoxy compound include bifunctional derivatives such as diethylene glycol diglycidyl ether, glycerin diglycidyl ether, and bisphenol A diglycidyl ether, and trifunctional derivatives such as trimethylolpropane triglycidyl ether. In addition, since the residual of a chlorine ion is unavoidable from the relationship which uses epichlorohydrin for a raw material, the epoxy compound from which the chlorine ion was removed as much as possible is desirable.

  Examples of the melamine resin include trimethylol melamine, hexamethylol melamine, trismethoxymethyl melamine, and hexakismethoxymethyl melamine.

  Examples of the isocyanate compound include aromatic polyisocyanates such as toluene diisocyanate and diphenylmethane diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, cyclohexane diisocyanate, and butane diisocyanate, and derivatives thereof. A blocked isocyanate compound is preferable in terms of enhancing the stability of the coating solution.

  Examples of the silane coupling agent include epoxy alkyl silanes and aminoalkyl silanes, and γ-glycidoxypropyltrimethoxysilane, γ (2-aminoethyl) aminopropyltrimethoxysilane, and the like are preferable.

  Examples of the polyethyleneimine include highly polar and high density polyamines having a branched structure composed of primary, secondary, and tertiary amines. In addition, examples of the water-soluble resin include a polyvinyl alcohol resin, and the polyvinyl alcohol resin preferably has a saponification degree of 89% or more and a molecular weight of 100 to 1,000.

  The mass ratio (A / B) between the water-dispersible polymer acrylic resin and the crosslinking agent needs to be 95/5 to 50/50, and preferably 90/10 to 60/40. If the cross-linking agent is less than 5%, the adhesion may not be good, and if it exceeds 50%, the curing reaction proceeds excessively, and conversely the impact resistance is lowered.

  In addition, as a catalyst of a crosslinking agent, an imidazole derivative such as 2-methylimidazole and 2-ethyl-4-methylimidazole, an epoxy ring-opening reaction catalyst such as a polyamine and a polyethyleneimine derivative, and a melamine crosslinking catalyst such as baratoluenesulfonic acid Catalysts for urethane crosslinking such as imidazole and organic tin compounds may be used. The amount of these catalysts is not particularly specified.

  The polyester film of the present invention may be a biaxially stretched film or an unstretched film. Here, the biaxial stretching method may be any of sequential biaxial stretching, simultaneous biaxial stretching, or a combination thereof. In the case of successive biaxial stretching, generally, a method of stretching in the longitudinal direction and then stretching in the transverse direction is adopted, but a method of stretching in the reverse order may be employed. In addition, it is preferable to fix the orientation of the polyester by heat treatment after biaxial stretching, 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 is not limited at all on one side or both sides of the film before or after the stretching step.

  Moreover, in this invention, Preferably it heat-processes at 140-270 degreeC after completion | finish of extending | stretching, Preferably it is 140-200 degreeC. At this time, by performing heat treatment while relaxing 2% or more in the vertical and / or horizontal direction, the operability at the time of canning can be improved.

  The film-laminated metal plate of the present invention is preferably laminated with the polyester film of the present invention so that the coating layer side is on the metal plate side. This is because the molding processability can be exhibited at the time of drawing by the adhesion of the coating layer.

  The method for laminating the polyester laminated film to the metal plate is not particularly limited. For example, a dry lamination method or a thermal lamination method can be employed. Specifically, after laminating by passing between nip rolls so that the polyester C layer of the polyester laminated film prepared above is in contact with the metal plate on a metal plate preheated to 220 ° C., a range of 10 to 40 ° C., for example, This is a method of laminating by rapid solidification in a 20 ° C. water bath.

  The film lamination may be performed on only 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.

  When the biaxially stretched film laminated metal plate in the present invention is applied to a two-piece can, a remelt treatment in which, after laminating, heating is performed at a temperature equal to or higher than the melting point of the polyester constituting the film, followed by rapid cooling in order to remove the polyester orientation. It is preferable to carry out. The degree of 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. This is because the delaminating phenomenon of peeling off occurs, torn or torn. 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. Because it can.

  The film laminated metal container of the present invention is a metal container formed by appropriately forming the biaxially stretched type or non-oriented type film laminated metal plate of the present invention, and the shape of the container, the method of forming the metal container, There is no particular limitation. Specifically, a so-called three-piece can in which the top cover is wound and filled with the contents, as well as a two-piece can that is formed by drawing a metal plate to form a container portion can be used.

  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. However, in the case of a two-piece can, it is preferable to use it on the inner wall surface side of the container so that the water-dispersible copolyester resin layer having excellent adhesion is in contact with the metal surface from the point of the drawing process appropriateness. It is.

In addition, when carrying out drawing ironing, you may apply | coat a lubricant to the film surface which a punch contacts as needed.
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 re-melt process after the can making process or the printing process.

  In addition, the polyester in the present invention may contain an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, a pigment, an antistatic agent, a lubricant, a crystal nucleating agent, a lubricant composed of inorganic or organic particles, if necessary. You may mix | blend.

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

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, it is not limited to the following.

  Various evaluation methods in the present invention are shown below.

・ Melting point of polyester, crystallization temperature of film and half width of crystallization peak Using DSC3100S made by Mac Science, put polyester film into sample pan, cover pan, and from room temperature to 280 ℃ under nitrogen gas atmosphere The temperature increase was measured at a temperature increase rate of 20 ° C./min. The temperature of the peak top of the melting peak appearing at this time was indicated as the melting point of the polyester film, the temperature of the peak top of the low temperature side peak was indicated as TmL (° C.), and the temperature of the peak top of the high temperature side peak was indicated as TmH (° C.).
Next, the sample having reached 280 ° C. was held as it was for 1 minute, and then the temperature was lowered to room temperature at a rate of 20 ° C./min. At this time, the temperature at the top of the recrystallization peak was defined as the crystallization temperature Tc2. Further, as shown in FIG. 1, the height h (mW), which is the amount of heat from the base line L to the peak top t of the crystallization peak 1, and the half width w (° C.) at the height h / 2. The ratio w / h (° C./mW) of the half width w and the height h was determined.

・ Reduced viscosity (ηsp / c)
0.125 g of polymer was dissolved in 25 ml of phenol / tetrachloroethane = 6/4 (weight ratio) and measured at 25 ° C. using an Ubbelohde viscometer. The unit is dl / g.

(3) Amount of inert particles of polyester Cut out as a sample. Using a fluorescent X-ray device (device name: ZSX100e) manufactured by Rigaku Corporation, each sample was measured from the upper and lower surfaces with an analysis diameter of 30 mmΦ, and converted to the amount of inert particles using a calibration curve for PET.

(4) Average particle diameter of inert particles The coating film sample dried overnight in a vacuum dryer is subjected to ion plasma etching, and the inert particles contained in the (I) and (II) layers of the base film. The particles were exposed. Subsequently, using a scanning electron microscope (SEM), the magnification was appropriately changed according to the size of the particles, and photography was performed. The equivalent circle diameter of at least 100 particles or more was obtained with an image processing apparatus, and divided by the number of particles to obtain a number-based average particle diameter (μm). When the contrast of the photographed particle was weak, the outline of the particle was traced on the OHP film with an ultra-fine magic pen, and the equivalent circle diameter of the particle was obtained with the image processing apparatus.
In addition, powder particles before adding particles to polyester are coated with a double-sided tape on a SEM sample table, and the powder is thinly deposited thereon. After carbon deposition, the particle size is measured using a scanning electron microscope (SEM). In accordance with this, the magnification was appropriately changed to take a picture. The equivalent circle diameter of at least 100 particles or more was obtained with an image processing apparatus, and divided by the number of particles to obtain a number-based average particle diameter (μm).

(5) Can manufacturing property The remelt aluminum plate obtained by the Example and the comparative example was manufactured by n = 10, and the buckling degree which arises in the upper part of a forming can was observed visually. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: Buckling has not occurred in the can opening △: 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

(6) Impact resistance [1]
Ten cans of 7 cm square were cut out from the center of the body wall of the cans obtained by making the remelt plates obtained in Examples and Comparative Examples, which were heated at 280 ° C. for 40 seconds and then quenched in water. A weight (600 g) having a tip diameter of 10 mm was dropped from a height of 10 cm on the surface corresponding to the outer surface of the sample, and the impact portion was immersed in an aqueous sodium hydroxide solution. The current value when 30 Sec was energized was measured and evaluated according to the following criteria.
×: 7 sheets or more are 5 mA or more Δ: 7 sheets or more are 1 mA or more ○: 7 sheets or more are less than 1 mA

(7) Impact resistance [2]
A 7 cm square sample is cut out from the center of the body wall of the can obtained by canning the remelt aluminum plate obtained in Examples / Comparative Examples after heating at 280 ° C. for 40 seconds and quenching in water. A weight (600 g) having a tip diameter of 10 mm is dropped from a height of 10 cm to the surface corresponding to the outer surface of the can of this sample to give an impact. Next, the sample was placed on a glass container filled with 7% dilute hydrochloric acid (with the convex portion of the sample immersed), and the corrosion state of the convex portion was visually observed after 3 days. Evaluation criteria were set as follows, and evaluations of ○ or higher were evaluated as practical.
A: 95 or more out of 100 samples are not corroded. ○: 80 to 94 out of 100 samples are not corroded. Δ: Out of 100 samples, 70 to 79 are not corroded. Some 100 out of 100 have some corrosion

(8) Remelt whitening The remelt aluminum plates obtained in the examples and comparative examples were visually observed. Evaluation criteria were set as follows, and evaluations of ○ or higher were evaluated as practical.
(Evaluation)
A: No whitening was observed before and after the heat treatment, and the gloss (degree) of the film was high.
○: Some whitening is observed, but the gloss (degree) of the film surface is high.
Δ: Whitening is observed, and the gloss (degree) of the film surface is low.
X: Whitening is remarkable and gloss (degree) of the film surface is low.

(9) 290 ° C. Remelt Whitening The film is laminated on an aluminum plate (3004 type alloy plate having a thickness of 0.26 mm) under the following conditions and left in a gear oven at 290 ° C. for 1 minute. Then, the one cooled by applying air at 25 ° C. to the film surface of the laminate at a wind speed of 20 m / min was judged visually.
(Lamination condition)
Lamination temperature: 220 ° C., linear pressure: 10 N / cm
Evaluation criteria were set as follows, and evaluations of ○ or higher were evaluated as practical.
(Evaluation)
A: No whitening was observed before and after the heat treatment, and the gloss (degree) of the film was high.
○: Some whitening is observed, but the gloss (degree) of the film surface is high.
Δ: Whitening is observed, and the gloss (degree) of the film surface is low.
X: Whitening is remarkable and gloss (degree) of the film surface is low.

(10) Dynamic friction measurement using steel balls as sliders in a 50 ° C environment (steel balls μ)
Three steel balls (according to JIS B1501 standard. Diameter 12.7 mmΦ) are arranged and fixed in a triangular shape so that the distance between the vertices is 25 mm at the measurement location of the remelt aluminum plate, A slider (weight = 0.5 kg) was set so as to come into contact with the measurement point at three points (one point at each vertex of each steel ball), and the dynamic friction coefficient when sliding at 200 mm / min was measured.

Example 1
[Polyester A]
PET: Polyethylene terephthalate (reduced viscosity = 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., the pressure was gradually reduced while the temperature was raised, and a polycondensation reaction was performed under a vacuum of 275 ° C. and 1.0 hPa or less. The obtained polyester (PET) resin having an intrinsic viscosity of 0.75 was used.

[Polyester B]
PBT: Polybutylene terephthalate (reduced viscosity = 1.30)
In a reactor equipped with an inlet, a thermometer, a pressure gauge, a distillation tube with a rectifying column, and a stirring blade, 86 parts by weight of 1,4-butanediol (1,4-butane with respect to 100 parts by weight of terephthalic acid) Diol / terephthalic acid molar ratio = 1.6), 0.05 parts by weight of tetranormal butyl titanate and 0.025 parts by weight of butylhydroxytin oxide were added, and water produced at 190 ° C. to 230 ° C. was distilled out of the system. The esterification reaction was carried out. 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 carried out at 250 ° C. under reduced pressure (1.0 hPa or less), and the resulting polyester (PBT) Resin was used.

Polyester A / Polyester B = 40/60 (% by weight), polyethylene wax (High Wax NL-500, manufactured by Mitsui Chemicals, Inc.) was added at 1000 ppm, and an organophosphorus compound (trimethyl phosphate, TMP manufactured by Ajinomoto Fine Techno Co., Ltd.) was added. A raw material added with 15% by weight was dried at 100 ° C. for 24 hours.
After melting at 270 ° C. using a single screw extruder, it was extruded from a T-die onto a cooling roll to obtain an unstretched sheet of resin. This unstretched sheet was stretched 3.3 times in the machine direction at a preheating temperature of 65 ° C. and a stretching temperature of 100 ° C., and further stretched by 4.0 times in the transverse direction at a preheating temperature of 65 ° C. and a stretching temperature of 90 ° C. After that, a heat treatment was performed at 160 ° C. for 8 seconds, and a relaxation treatment of 4% was performed at 160 ° C. to obtain a biaxially stretched film having a thickness of 20 μm. The film was coated with a polymer acrylic resin coating solution (Vinyl Blanc 2585, manufactured by Nissin Chemical Industry Co., Ltd.) adjusted to have a coating layer thickness of 700 nm by a gravure coating method. Dry for 2 seconds.

[Production of film-laminated metal plate]
A linear pressure is applied by passing between nip rolls so that the polymer acrylic resin layer of the polyester film prepared above is in contact with the aluminum plate (3004 series alloy plate having a thickness of 0.26 mm) on both sides of the aluminum plate preheated to 220 ° C. After laminating at 10 N / cm, heat treatment was performed, and immediately after that, quenching was performed in a 20 ° C. water bath to obtain an aluminum plate having films laminated on both sides. At the time of laminating, there was no initial adhesion, tension fluctuation, winding around a nip roll, etc., and the laminating suitability of the laminated film of this example was good.
Next, the film-laminated aluminum plate was heated at 270 ° C. for 40 seconds, then air-cooled, and further quenched in water at 20 ° C. to prepare a remelt aluminum plate. The finished remelt aluminum plate had good 50 ° C. steel ball sliding properties, and there was no change in appearance due to whitening of the film even during rapid cooling after heat treatment.

[Production of film-laminated metal container]
The remelt aluminum plate produced above was drawn and ironed so that the thickness reduction rate was 30% to form a film laminated metal container. At the time of molding, there was no peeling or tearing of the film, and the releasability from the mold was good. Furthermore, after printing the outer surface, a varnish was applied, and after heat-curing, it was quenched with cold air.
The container thus formed was filled with a beverage, and a lid with a tab was wound and joined to produce a two-piece beverage can.
The resulting beverage can has excellent can-making properties, no elution of oligomers into the beverage or precipitation from the film, and film breakage due to external impacts expected during the distribution stage or low temperature storage There wasn't.

(Example 2)
A two-piece beverage can was produced according to Example 1 except that the mixing ratio of polyester was polyester A / polyester B = 50/50 (% by weight). The resulting beverage can is excellent in canability as in Example 1, is free from oligomer elution into the beverage and deposited from the film, and is resistant to external impacts expected during the distribution stage and low-temperature storage. There was no tearing of the film.

(Example 3)
The coating formulation was carried out except that a polymer acrylic resin (Vinyl Blanc 2585 manufactured by Nissin Chemical Industry Co., Ltd.) and an epoxy crosslinking agent (CR-50 manufactured by DIC) were mixed at a mass ratio of 80/20. A two-piece beverage can was manufactured according to Example-1. The resulting beverage can is excellent in canability as in Example-1 and there is no elution of oligomers into the beverage or precipitation from the film, and further against external impacts expected during the distribution stage and low temperature storage. But there was no tearing of the film.

Example 4
As a coating formulation, a polymer acrylic resin (Vinyl Blanc 2585 manufactured by Nissin Chemical Industry Co., Ltd.) and an epoxy crosslinking agent (CR-50 manufactured by DIC) were mixed at a mass ratio of 80/20, and the coating thickness was adjusted to 2000 nm. A two-piece beverage can was produced according to Example 1 except that. The resulting beverage can is excellent in canability as in Example 1, is free from oligomer elution into the beverage and deposited from the film, and is resistant to external impacts expected during the distribution stage and low-temperature storage. There was no tearing of the film.

(Comparative Example 1)
Polyester A / polyester B = 40/60 (% by weight), a material added with 1000 ppm of polyethylene wax (High Wax NL-500, manufactured by Mitsui Chemicals, Inc.) dried at 100 ° C. for 24 hours was used.
After melting at 290 ° C. using a single screw extruder, it was extruded from a T-die onto a cooling roll to obtain an unstretched sheet of resin. This unstretched sheet was stretched 3.3 times in the machine direction at a preheating temperature of 65 ° C. and a stretching temperature of 100 ° C., and further stretched by 4.0 times in the transverse direction at a preheating temperature of 65 ° C. and a stretching temperature of 90 ° C. After that, a heat treatment was performed at 160 ° C. for 8 seconds, and a relaxation treatment of 4% was performed at 160 ° C. to obtain a biaxially stretched film having a thickness of 20 μm. The film was coated with a coating solution (Vinyl Blanc 2585 manufactured by Nissin Chemical Industry Co., Ltd.) adjusted to a thickness of 700 nm by a gravure coating method, and dried at 160 ° C. for 8 seconds. .
About the can manufacturing process and evaluation after this, it applies to Example 1.
The resulting beverage can had good impact resistance, but did not reach the quality in the examples in terms of remelt whitening and canability.

(Comparative Example 2)
The coating thickness is obtained by mixing a polymer acrylic resin (Vinyl Blanc 2585 manufactured by Nissin Chemical Industry Co., Ltd.) and a melamine cross-linking agent (Beckamine M-3 manufactured by DIC) at a mass ratio of 80/20. A two-piece beverage can was produced in accordance with Example 1 except that was adjusted to 300 nm. The resulting beverage can had good can-making properties and remelt whitening, but the impact resistance was not as good as the quality in the examples.

(Comparative Example 3)
Poester A / polyester C = 40/60 (% by weight), polyethylene wax (high wax NL-500 manufactured by Mitsui Chemicals, Inc.) was added at 1000 ppm, and organophosphorus compound (trimethyl phosphate, TMP manufactured by Ajinomoto Fine Techno Co., Ltd.) was added. A raw material added with 15% by weight was dried at 100 ° C. for 24 hours. For polyester C, isophthalic acid 10 mol% copolymerized PET was used. Otherwise, a two-piece beverage can was produced according to Example 1. The resulting beverage can had good impact resistance, but did not reach the quality in the examples in terms of remelt whitening and canability.

(Comparative Example 4)
Polyester A / Polyester B = 40/60 (% by weight), 100 ppm of polyethylene wax (High Wax NL-500 manufactured by Mitsui Chemicals, Inc.) was added, and an organophosphorus compound (trimethyl phosphate, TMP manufactured by Ajinomoto Fine Techno Co., Ltd.) was added. A raw material added with 15% by weight was dried at 100 ° C. for 24 hours. Otherwise, a two-piece beverage can was produced according to Example 1. The resulting beverage cans had good impact resistance and remelt whitening properties, but did not reach the quality in the examples in terms of can production.

  The results are shown in Tables 1 and 2.

  The squeezed iron can coating film of the present invention is excellent in molding processability and retort resistance in can manufacturing, and is excellent in impact resistance during low-temperature storage and transfer, and is used as a laminate film for two-piece cans. It is possible to contribute to the industry.

It is explanatory drawing of the calculation method of ratio w / h (degreeC / mW) of half value width w and height h.

Claims (8)

  A polyester-based resin film in which a base layer made of a polyester-based resin is provided with a coating layer made of a polymer acrylic resin, the polyester (A) having 10 to 90% by weight of polyester (A) containing ethylene terephthalate as a main constituent, ) And a polyester resin composition blended with 90 to 10% by weight of a crystalline polyester (B) different from), containing a wax of 500 ppm or more, at the time of temperature drop in a differential scanning calorimeter (DSC) The ratio w / h of the half-value width w (° C.) and the height h (mW) of the recrystallization peak (Tc2) is 2.30 (° C./mW) or less, and the coating layer thickness of the polymer acrylic resin Is a polyester film for covering a squeezed iron can, characterized by having a thickness in the range of 500 nm to 5000 nm.   The polyester film for covering a drawn and ironed can according to claim 1, wherein the coating layer is a water-dispersible polymer acrylic resin or a water-dispersible polymer acrylic resin and a water-soluble or water-dispersible epoxy compound, melamine A polyester film for covering a squeezed iron can characterized by containing one or more crosslinking agents selected from a series resin, an isocyanate compound, a silane coupling agent, polyethyleneimine, and polyvinyl alcohol.   A polyester film for covering a drawn iron can according to claim 1, wherein the polymer acrylic resin has a Tg of 40 ° C or higher and 70 ° C or lower.   2. The polyester film for covering a drawn iron can according to claim 1, wherein the coating layer is provided by a coating treatment.   2. A polyester film for covering a drawn iron can according to claim 1, wherein the polyester resin composition has a reduced viscosity of 0.80 or more.   A metal plate for a drawn and ironed can, characterized in that the polyester film according to claim 1, 2, 3, 4 or 5 is coated on a metal plate.   The metal plate for a drawn iron can according to claim 6, wherein the film is remelted.   6. A squeezed iron can made from the film-coated metal plate according to claim 5.