JP5458618B2 - Film for squeezing and ironing can coating - Google Patents

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 that is suitably used for coating the outer surface of a drawn iron can. More specifically, the present invention relates to a film for covering the outer surface of a drawn and ironed can excellent in canning processability such as drawing and ironing.

  As a method for preventing corrosion of the inner wall surface and the outer wall surface of a metal can, there is a method of laminating a thermoplastic resin film. A polyester film for laminating a metal material for food canning is disclosed (for example, see Patent Document 1).

  This polyester film has excellent scratch resistance. For example, in a can manufacturing process in which a metal plate is formed into a cylinder and a lid is wound around the upper and lower openings of the cylinder, , "Film laminated metal plate"), or when the laminated metal plate is processed by winding or the like, there is no need to cause scratches and reduce the commercial value.

  In addition, this film has excellent resistance at the time of squeezing processing, and after being filled with food after canning, the amount of oligomer elution is small when heated hot water treatment such as retort treatment is performed, so it is laminated on the inner wall surface of a metal container. Excellent as a polyester film.

  By the way, for food cans, in addition to the so-called three-piece cans, which are formed by cylindrically forming a metal plate, a lid is attached to the upper and lower openings of the metal cylinder, and a metal plate is deep drawn to form a container part. In addition, 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. If the formability is insufficient or the film adheres poorly to the metal plate, a so-called delaminating phenomenon occurs in which the film peels 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.

  Furthermore, in the drawing process, the film laminated metal plate is processed into a container shape while repeatedly raising and lowering the punch. Therefore, in the case of a film laminated on the inner wall surface side of the container, releasability from the punch is required. The In the case of the outer wall surface of a container, the temperature at the time of canning tends to rise due to the friction temperature due to the material and thickness of the metal plate, and the heat resistance temperature of the film may be exceeded. Since there is a problem of deteriorating canability, it is necessary to have excellent releasability from the die.

  Alkylene oxide having 2 or more carbon atoms derived from the polyoxyalkylene glycol component as a metal laminating film that can be applied as a laminate film for two-piece cans and has excellent moldability in can manufacturing and excellent beverage flavor A film for laminating a metal plate comprising a thermoplastic polyester resin composition containing 2 to 20 mol% of the total acid amount of the polyester resin composition, the melting point of the film existing on the metal substrate. After remelting (so-called remelt treatment) with the above heat, rapidly cooling and making cans, the dynamic friction coefficient of the film surface with a steel ball loaded with a load of 2 kg at 150 ° C. is 0. A film of 20 or less is disclosed (for example, see Patent Document 2).

  However, further improvement of the laminating property to the metal plate is demanded, and these films are not satisfactory.

JP-A-7-227946 JP 2009-13244 A

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

  The film for covering a squeezed iron can according to the present invention, which has achieved the above object, is a thermoplastic polyester film comprising a thermoplastic polyester A layer and a thermoplastic polyester B layer, the thermoplastic polyester A layer and the thermoplastic polyester A layer The thermoplastic polyester B layer is composed of a polyester resin composition mainly composed of a copolymer polyester composed of an ethylene terephthalate component and an ethylene isophthalate component, and contains 0.50 to 1.50% by weight of inert particles having a particle size of 3 to 5 μm. And a film for covering a squeezed iron can, characterized in that the content of inert particles having a particle size of 3 to 5 μm is 0.4% by weight or less, wherein the film present on the metal substrate is bonded together. In a 150 ° C environment after remelting (so-called remelt treatment) with heat above its melting point, rapidly cooling and making cans The dynamic friction coefficient of the film surface using a steel ball loaded with a load of 2 kg as a slider is 0.20 or less.

  In this case, the weight average molecular weight (A) of the thermoplastic polyester film and the film existing on the metal substrate are remelted by heat above its melting point (so-called remelt treatment) and rapidly cooled to form a can. It is preferable that the weight average molecular weight (B) after the heating is 40,000 or more.

In this case, it is preferable that the weight average molecular weights (A) and (B) of the thermoplastic polyester film satisfy the relationship of the following formula 1.
(B) / (A) ≦ 1 (1)

  Furthermore, in this case, it is preferable that the thermoplastic polyester film contains 0.01 to 1.0% by weight of an antioxidant.

  Furthermore, in the thermoplastic polyester film, it is preferable that the alkylene oxide unit having 2 or more carbon atoms derived from the polyoxyalkylene glycol component contains 1 to 20 mol% with respect to the total acid amount of the polyester film. is there.

  In this case, a metal plate for a drawn and ironed can, which is characterized in that the thermoplastic polyester film is coated on a metal plate, is useful.

  Furthermore, in this case, a squeezing and ironing can characterized in that the film-coated metal plate can be made is useful.

  When used as a laminate film for a two-piece can, the drawn and ironed can coating film of the present invention is excellent in molding processability, particularly releasability from a die during can making.

  The drawn iron can coating film of the present invention is a thermoplastic polyester film comprising a thermoplastic polyester A layer and a thermoplastic polyester B layer, each layer comprising an ethylene terephthalate component and an ethylene isophthalate component. It consists of a polyester resin composition mainly composed of polymerized polyester.

At this time, in the film of the thermoplastic polyester A layer and the thermoplastic polyester B layer, it is preferable that the melting peak exists in the range of 246 ° C to 252 ° C. If the melting peak is less than 246 ° C, the heat resistance and canability in the canning process are impaired, and the outer surface is scraped (so-called galling), which is not preferable. If it exceeds 252 ° C, the temperature balance in the remelt treatment is Both are not preferred because they collapse and the yield decreases.
It is preferable that the copolymerization amount of the isophthalic acid component of the copolymerized polyester in which each layer is composed of an ethylene terephthalate component and an ethylene isophthalate component is 0.5 to 1.5 mol%.

In this invention, the said other copolymerization component can be included in the range which does not inhibit the objective.
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 dicarboxylic acids and their ester derivatives that can be used is preferably 10 mol% or less, more preferably 6 mol% or less. When the usage-amount of other dicarboxylic acid and those ester derivatives exceeds 10 mol%, the thermal stability of polyester will worsen and it is unpreferable.

Among the other copolymerizable components that can be used, as the glycol component, components that can be used in addition to the ethylene glycol component include aliphatic glycols such as propanediol, butanediol, pentanediol, hexanediol, neopentylglycol, and cyclohexanediethylene. Aromatic glycols such as methanol, aromatic glycols such as ethylene oxide adducts of bisphenol A, ethylene oxide adducts 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 other glycol components that can be used is preferably 10 mol% or less, more preferably 5 mol% or less. If the amount of the other glycol component used exceeds 10 mol%, the thermal stability of the polyester deteriorates, which is not preferable.

  The film of the present invention preferably has a thermoplastic polyester film B layer bonded to a metal plate.

  Moreover, in the said thermoplastic polyester, it is preferable that a melting peak exists in the range of 240 to 252 degreeC. When the melting peak is less than 240 ° C., the heat resistance in the can making process is reduced, sticking between the forming punch and the film occurs, and the punch is not smoothly removed, and the can is liable to be deformed. On the other hand, when it exceeds 252 ° C., there is a problem that the temperature balance in the remelt treatment is lost, or the film is easily cut during molding.

In the thermoplastic polyester resin composition of the present invention, the number of repeating alkylene oxide units having 2 or more carbon atoms is 3 or more in order to improve the molding adhesion and tearability at the time of making a film-laminated metal plate. It is preferable to contain a certain polyoxyalkylene glycol component in the range of 2 to 10 wt%. By containing the said component in this range, the adhesiveness with the metal plate at the time of shaping | molding can be improved with the effect of providing the elasticity at normal temperature and low temperature of a thermoplastic polyester film.
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.

In the present invention, the amount of the polyoxyalkylene glycol component contained in the thermoplastic polyester resin composition used in the thermoplastic polyester A layer and the thermoplastic polyester B layer is 2 carbon atoms derived from the polyoxyalkylene glycol component. The amount of one or more alkylene oxide units is preferably 1 to 20 mol% with respect to the total acid component of the polyester composition. 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 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 sheet The handleability may be deteriorated.
In addition, the amount of the polyoxyalkylene glycol component contained in the thermoplastic polyester resin composition is more preferably 1 to 10 mol%, and particularly preferably 1 to 5 mol%.

  The method for containing the polyoxyalkylene glycol component in the thermoplastic polyester resin 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 of a resin layer in the same manner as other raw materials and then terminating the polyester synthesis reaction may be used. Another copolymerized polyester copolymerized with oxyalkylene glycol may be melt-mixed with the thermoplastic polyester resin 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, as another copolymerized polyester obtained by copolymerizing polyoxyalkylene glycol, for example, a method of adding a polyalkylene terephthalate-polytetramethylene oxide block copolymer to polyethylene terephthalate can be mentioned. Examples of the polyalkylene terephthalate include polybutylene terephthalate, and polybutylene terephthalate is preferable, and a polyalkylene terephthalate-polytetramethylene oxide block copolymer is most preferable.
At this time, the ratio of the polyoxyalkylene glycol in the block copolymer is preferably 20 to 60% by weight, and more preferably 30 to 50% by weight.

In the squeezing and ironing can coating film of the present invention, it is preferable that the content of the low molecular weight compound is smaller in view of the antifouling property of the can manufacturing line and the fragrance retention property in the case of the inner surface of the can. For example, the ethylene terephthalate cyclic trimer content in the thermoplastic resin after canning in the present invention is preferably 0.7% by weight or less. In the case of producing a two-piece can, after undergoing a remelt process for making the film non-oriented, after being drawn, the beverage is filled and subjected to a heat treatment such as a retort process. This is to prevent the oligomer from being eluted from the film in each step, and further transferring the oligomer to the beverage and adversely affecting the taste and flavor of the beverage.
In the present invention, a copolymerized polyester composed of an ethylene terephthalate component and an ethylene isophthalate component in the thermoplastic polyester resin composition used for each of the thermoplastic polyester A layer and the thermoplastic polyester B layer is contained in the thermoplastic polyester resin composition. The types and amounts of the polyoxyalkylene glycol components are preferably the same.

The film for covering a squeezed iron can according to the present invention is a film for laminating a metal plate made of a thermoplastic polyester resin composition, and the film existing on the metal substrate is remelted by heat above its melting point (so-called remelt). It is preferable that the dynamic friction coefficient of the film surface having a steel ball loaded with a load of 2 kg in a 150 ° C. environment after being rapidly cooled and canned is 0.20 or less. This is for obtaining releasability from the die during can making. In a highly rigid metal plate such as a steel plate, the temperature at the time of canning tends to rise due to friction at the time of canning. Particularly in the case of an outer film, it is necessary to provide slipperiness at a high temperature to avoid this problem. Here, if the dynamic friction coefficient of the film surface using a steel ball loaded with a load of 2 kg in an environment of 150 ° C. exceeds 0.20, the releasability between the film and the die during can making decreases. As a result, the can-making temperature is raised, and as a result, scratches (so-called galling) with the dice are generated.
In order to obtain the dynamic friction coefficient, the surface roughness after remelting of the thermoplastic polyester A layer is controlled to the maximum height (SRmax): 4 μm or more and the center surface average roughness (SRa): 0.2 μm or more. Achieved.

  In order to achieve the above-mentioned film surface formation and to make the dynamic friction coefficient of the film surface having a steel ball loaded with a load of 2 kg under a 150 ° C. environment as a slider, it is inactive as a lubricant particle. It is preferable to use inorganic particles or crosslinked polymer particles.

  Examples of the inert particles include silica, alumina, kaolin, clay, titanium oxide, calcium phosphate, calcium carbonate, lithium fluoride, barium sulfate, and carbon black.

  Examples of the crosslinked polymer particles include acrylic monomers such as acrylic acid, methacrylic acid, acrylic acid esters and methacrylic acid esters, styrene monomers such as styrene and alkyl-substituted styrene, and divinylbenzene. , Divinyl sulfone, ethylene glycol dimethacrylate, trimethylolpropane trimethyl acrylate, copolymers with crosslinkable monomers such as pentaerythritol tetramethyl acrylate; melamine resin; benzoguanamine resin; phenol resin; silicon-containing resin Etc. can be illustrated.

  The average particle size of the particulate lubricant is preferably 3 to 5 μm. This is because if it is less than 3 μm, the effect of improving the releasability from the die cannot be exhibited. On the other hand, if the thickness exceeds 5 μm, the effect of improving the releasability with the die is saturated, but the lubricant is dropped due to abrasion, and the film-forming property is lowered during film formation, which is not economical.

The amount of the lubricant is preferably 0.50 to 1.50% by weight on the polyester A layer side. This is because a lubricant amount of 0.5% by weight or more is preferable in order to make the dynamic friction coefficient in an environment of 150 ° C. 0.20 or less. On the other hand, even if it contains an amount exceeding 1.5% by weight, the effect of releasability does not change, and the film-forming property is lowered at the time of film formation, which is not economical.
The lubricant content on the polyester B layer side in contact with the metal surface is preferably 0.40% by weight or less. Thereby, adhesiveness with the metal plate after lamination and remelting can be improved, and the deformation | transformation of the can at the time of shaping | molding can be prevented.

The film for covering a squeezed iron can according to the present invention preferably contains 0.01 to 1% by weight of an antioxidant. This is because the film is bonded to a metal substrate, and the molecular weight of the film is reduced in the remelting process (so-called remelt treatment) and the can making process by heat higher than the melting point of the film, thereby improving the can manufacturing performance. This is to make it happen. In particular, the polyalkylene glycol component is susceptible to thermal decomposition in the remelting (so-called remelting) process and the can-making process. When the antioxidant is less than 0.01% by weight, the molecular weight is greatly reduced in the laminating / remelting process. To do. Moreover, even if it contains 1 weight% or more, an effect does not change and it becomes disadvantageous in cost.
This is because the thermal decomposition of the polyoxyalkylene glycol component contained in the thermoplastic polyester resin composition is linked to the entire thermoplastic polyester resin component.

  Antioxidants used in the film for squeezing and ironing can coating of the present invention include primary antioxidants (which have a phenol-based or amine-based radical scavenging and chain termination action), and secondary antioxidants (this Have a phosphorus decomposition action such as phosphorus-based and sulfur-based), and 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 method for setting the content of the cyclic trimer including the ethylene terephthalate cyclic trimer in the polyester film to 0.7% by weight or less is not particularly limited. 1. a method of extracting and removing the cyclic trimer from the laminated film with water or an organic solvent after the laminated film is formed; Examples thereof include a method of forming a polyester film using a polyester having a small cyclic trimer. Of these, 2. This method is more economical and preferable.
2. In this method, the method for producing a polyester having a low cyclic trimer content is not limited, and the solid phase polymerization method: after polymerization, the cyclic trimer is extracted by heat treatment under reduced pressure or by extraction with water or an organic solvent. A removal method; and a combination of 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.

  The polyester used in the present invention is synthesized by a known method such as a direct esterification method in which a dicarboxylic acid and a diol are directly reacted; a transesterification method in which a dimethyl ester of a dicarboxylic acid is reacted with a diol. Each of these methods may be performed by either a batch method or a continuous method. Alternatively, a solid phase polymerization method may be used to increase the molecular weight. The solid phase polymerization method is preferable from the viewpoint of reducing the content of the cyclic trimer as described above. The polyester synthesized in this way may be included in the polyester film only in one kind or in a mixture of two or more kinds.

  The intrinsic viscosity of the polyester film when the various components are mixed is preferably in the range of 0.6 to 1.2. If the intrinsic viscosity of the polyester is less than 0.6, the mechanical properties of the resulting film may be lowered. If the polyester exceeds 1.2, the effect of the mechanical properties will not change, and the productivity of the raw material polyester will also be improved. It is not economical because it decreases.

  The 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.

  The method for laminating the film of the present invention on a metal plate is not particularly limited. For example, a dry lamination method or a thermal lamination method can be employed. Specifically, the metal plate is heated above the melting point of the laminate surface of the film, the film is brought into contact with the surface of the metal plate, and the nip roll is passed in this state. Subsequently, it laminates by making it cool and solidify in a 10-40 degreeC water tank.

  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. Is preferably performed. 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.

In addition, when carrying out drawing ironing, you may apply | coat a lubricant to the film surface which a punch and die | dye contact 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 to the additives and lubricants mentioned so far, the film in the present invention may contain an ultraviolet absorber, a plasticizer, a pigment, an antistatic agent, a lubricant, a crystal nucleating agent, etc. as necessary. May be.

  In the present invention, the metal plate is not particularly limited, but a surface-treated steel plate such as tin free steel, an aluminum plate, an aluminum alloy plate, an aluminum plate or a surface-treated aluminum plate, or the like can be used.

Hereinafter, the present invention will be described based on examples.
Various evaluation methods in the present invention are shown below.

(1) Dynamic friction measurement using a steel ball as a slider in a 150 ° C environment (steel ball μ)
Three steel balls (according to JIS B1501 standard. Diameter 12.7 mmΦ) are arranged and fixed in a triangular shape at a measurement point of the remelt aluminum plate at a distance of 25 mm each in a triangular shape. A slider (weight = 2.0 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.

(2) Molecular weight of film Aluminum was removed from the remelt plate or can product by hydrochloric acid treatment, and 2 mg of the film was sampled. Each was immersed in 0.4 ml of HFIP / chloroform = 2/3 (v / v), dissolved, and then adjusted to 8 ml with chloroform. It filtered with the 0.2 micrometer membrane filter, and used the filtrate for GPC.
Equipment: TOSOH HLC-8220GPC
Column: TSKgel SuperHM-H × 2 + TSKgel SuperH2000
(TOSOH)
Solvent: chloroform / HFIP = 98/2 (v / v),
Flow rate: 0.6 ml / min
Concentration: 0.025%
Temperature: 40 ° C
Detector: UV 254nm
The molecular weight was calculated in terms of standard polystyrene (PS).

(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 ion plasma etching treatment was performed on the coating film sample dried overnight in a vacuum dryer, 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-making properties After forming a laminated metal plate into a cup by drawing, 300 cans are continuously produced by redrawing and ironing under the following forming conditions at a speed of 80 cans / minute, and scratches occur on the outer surface of the formed can. The degree of (so-called galling) was visually observed, the ratio of the number of generated cans was set as the following evaluation criteria, and ○ was evaluated as practical.
As used herein, galling occurs during can making, is caused by contact between the outer surface of the forming can and the forming jig, and is often linear.
○: Scratch occurrence rate on the outer surface of the can 5% or less △: Scratch occurrence rate on the outer surface of the can 30% to 6%
×: Scratch generation rate of 31% or more on outer surface of can (molding conditions)
Blank diameter: 152mm
Aperture ratio: 1.60
Redraw ratio: 1.44
Ironing ratio of can body side wall: 56%
[However, the ironing rate is calculated from (t ₀ −t ₁ ) / t ₀ × 100, t ₀ : plate thickness before processing, t ₁ : calculated from plate thickness of can barrel side wall after processing]

(5) Evaluation of laminating properties Laminate by passing between 2 kg / cm-pressure nip rolls on a metal plate preheated to 245 ° C. by a thermal laminating method so that the polyester B layer of the polyester laminated film prepared above is in contact with the metal plate. Then, it is rapidly cooled and solidified in a 10-40 ° C. water bath.
At that time, it is visually determined whether the laminate is lifted.

Next, the kind and content of polyester used for the Example and the comparative example are demonstrated.
A: Polyethylene terephthalate (IV = 0.73)
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 and 0.05 mol% of magnesium acetate as the Mg element are charged with respect to the acid component, and nitrogen is introduced while stirring to bring the pressure in the system to 0.3 MPa. The esterification reaction was carried out while distilling out the water produced 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 intrinsic viscosity 0.73 polyester (PET) resin was used.

B: Polyethylene terephthalate / isophthalate (3.2 mol% ethylene isophthalate repeating unit, IV = 0.74, 0.5 wt% ethylene terephthalate cyclic trimer).
A reactor equipped with an inlet, a thermometer, a pressure gauge, a distillation tube with a rectifying column, and a stirring blade was added to 96.8 parts by weight of terephthalic acid, 3.2 parts by weight of isophthalic acid, 82 parts by weight of ethylene glycol (ethylene glycol / The molar ratio of all acid components = 2.2), 0.05 mol% of germanium oxide as the Ge element and 0.05 mol% of magnesium acetate as the Mg element were charged with respect to the acid component, and nitrogen was introduced while stirring. The esterification reaction was carried out while maintaining the pressure in the system at 0.3 MPa and distilling off the water produced at a temperature of 230 ° C. to 250 ° C. outside the system. After completion of the reaction, at 250 ° C., 0.04 mol% of trimethyl phosphate is added as the P amount, the pressure is gradually reduced while the temperature is raised, and a polycondensation reaction is performed under a vacuum of 275 ° C. and 1.0 hPa or less. Obtained. Subsequently, this polyester was heat-treated at 200 ° C. under a vacuum of 1.0 hPa for 12 hours to obtain PET-I (3.2). The polyester obtained had an intrinsic viscosity of 0.74 (dl / g) and an ethylene terephthalate cyclic trimer of 0.5% by weight.

C: Polytetramethylene terephthalate-polytetramethylene oxide block copolymer polyester In a reactor equipped with an inlet, a thermometer, a pressure gauge, a distillation tube with a rectifying column, and a stirring blade, with respect to 100 parts by weight of dimethyl terephthalate , 75 parts by weight of 1,4-butanediol, 75 parts by weight of polytetramethylene glycol (average molecular weight 1000), and 0.05 parts by weight of normal butyl titanate were distilled out of the system at 190 ° C. to 230 ° C. The transesterification 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 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). (Brand GP301 manufactured by Toyobo)

D: Polyester containing 5% by weight of antioxidant 5 parts by weight of phenolic antioxidant (Irganox 1010, manufactured by Ciba Geigy) is melt-kneaded with 95 parts by weight of polyester A, and oxidized. A polyester resin (D) containing 5% of an inhibitor was obtained.
E: Lubricant masterbatch-1
90 parts by weight of polyester A and 10 parts by weight of SiO ₂ having an average particle diameter of 5 μm were melt-kneaded with a twin screw extruder to obtain a polyester resin (E) containing 25% of SiO ₂ .
F: Lubricant masterbatch-2
90 parts by weight of polyester A and 10 parts by weight of PMMA having an average particle size of 5 μm were melt-kneaded with a twin screw extruder to obtain a polyester resin (F) containing 5% SiO ₂ .
G: Lubricant masterbatch-3
90 parts by weight of polyester A and 10 parts by weight of SiO ₂ having an average particle diameter of 3 μm were melt-kneaded with a twin screw extruder to obtain a polyester resin (G) containing 5% SiO ₂ .
H: Lubricant masterbatch-4
90 parts by weight of polyester A and 10 parts by weight of SiO ₂ having an average particle diameter of 2 μm were melt-kneaded using a twin screw extruder to obtain a polyester resin (G) containing 5% of SiO ₂ .

Example 1
[Production of polyester film]
As polyester A layer, polyester A / B / C / D / E = 50/32/4/4/10 (% by weight) as a raw material is dried at 100 ° C. for 24 hours, and as polyester B layer, polyester A / B / C / D / E = 56/32/4/4/4 (% by weight) was dried at 100 ° C. for 24 hours and then melted at 270 ° C. using a single-screw extruder, and then two layers from the 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. A polyester film having a thickness of 10 μm was obtained by heat treatment at 8 ° C. for 8 seconds.

[Production of film-laminated metal plate]
Passing between the nip rolls and laminating so that the polyester film B layer side prepared above and the aluminum plate are in contact with both surfaces of the preheated aluminum plate, heat treatment is performed, and immediately in a 10-40 ° C. water bath. Quenching was performed to obtain an aluminum plate having a film 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 subjected to 90 Sec heat treatment at 270 ° C. and then air-cooled and further quenched in water to prepare a remelt aluminum plate. In remelting, there was no reduction in molecular weight, and a remelting plate having a good dynamic friction coefficient using a steel ball as a slider under an environment of 150 ° C. was obtained.

[Production of film-laminated metal container]
The remelted aluminum plate produced above was drawn and ironed so that the thickness reduction rate was 30% to form a film laminated metal container. The obtained can product had no film molecular weight reduction, a good dynamic friction coefficient using a steel ball in a 150 ° C. environment as a slide, no galling or tearing on the outer surface, and excellent can manufacturing performance.
The results are shown in Table 1, Table 2, and Table 3.

(Example 2)
Example-1 for the subsequent film-forming / can-making processes and evaluations except that A / B / C / D / F = 50/32/4/4/10 (wt%) was used as the raw material for the polyester A layer. According to
As in Example 1, the resulting can product had a good coefficient of dynamic friction using a steel ball in a 150 ° C. environment as a slider, and there was no galling or tearing on the outer surface, and the can product was excellent.
The results are shown in Table 1, Table 2, and Table 3.

(Example 3)
Except for the polyester A / B / C / D / G = 50/32/4/4/10 (% by weight) as the raw material for the polyester A layer, the film-forming and can-making processes and evaluations thereafter are described in Examples- Same as 1.
As in Example 1, the resulting can product had a good coefficient of dynamic friction using a steel ball in a 150 ° C. environment as a slider, and there was no galling or tearing on the outer surface, and the can product was excellent.
The results are shown in Table 1, Table 2, and Table 3.

Example 4
Example 1 for the subsequent film-forming and can-making processes and evaluations except that polyester A / B / C / D / E = 50/32/4/4/10 (wt%) was used as the raw material for the polyester A layer. According to
As in Example 1, the resulting can product had a good dynamic friction coefficient with a steel ball in a 150 ° C. environment as a slider, was free from galling or tearing on the outer surface, and was excellent in can manufacturing performance. .
The results are shown in Table 1, Table 2, and Table 3.

(Example 5)
Example 1 for the subsequent film-forming and can-making processes and evaluations except that polyester A / B / C / D / E = 54/30/5/1/10 (wt%) was used as the raw material for the polyester A layer. According to
As in Example 1, the resulting can product had a good dynamic friction coefficient with a steel ball in a 150 ° C. environment as a slider, was free from galling or tearing on the outer surface, and was excellent in can manufacturing performance. .
The results are shown in Table 1, Table 2, and Table 3.

(Comparative Example 1)
Example 1 for the subsequent film-forming and can-making processes and evaluations except that polyester A / B / C / D / H = 50/32/4/4/10 (wt%) was used as the raw material for the polyester A layer. According to
Although the resulting beverage can did not have a decrease in molecular weight or the like, galling frequently occurred at the time of can making, and did not reach the quality in the examples.
The results are shown in Table 1, Table 2, and Table 3.

(Comparative Example 2)
About the subsequent film-forming / can-making process and evaluation, except that polyester A / B / C / D / E = 50 / 41.7 / 4/4 / 0.3 (weight%) was used as the raw material for the polyester A layer. Corresponds to Example 1.
Although the resulting beverage can did not have a decrease in molecular weight or the like, galling frequently occurred at the time of can making, and did not reach the quality in the examples.
The results are shown in Table 1, Table 2, and Table 3.

(Comparative Example 3)
About the subsequent film-forming / can-making process and evaluation, except that polyester A / B / C / D / E = 50 / 35.9 / 4 / 0.1 / 10 (% by weight) was used as the raw material for the polyester A layer. Corresponds to Example 1.
The resulting beverage can had a decrease in molecular weight, resulting in a decrease in can-making ability, and did not reach the quality in the examples.
The results are shown in Table 1, Table 2, and Table 3.

(Comparative Example 4)
Example 1 for the subsequent film-forming / can-making process and evaluation, except that polyester A / B / C / D / E = 0/76/4/4/10 (wt%) was used as the raw material for the polyester A layer. According to
The resulting beverage can had a lower melting point, so that the can-making ability was lowered and the quality in the examples was not reached.
The results are shown in Table 1, Table 2, and Table 3.

(Comparative Example 5)
Polyester A / B / C / D / E = 50/32/4/4/10 (wt%) as a raw material for the polyester A layer, and polyester A / B / C / D / E = 50 as a raw material for the polyester B layer Except for setting / 32/4/4/10 (% by weight), the subsequent film-forming / can-making process and evaluation are in accordance with Example 1.
Adhesion decreased during lamination, and lamination was not possible.
The results are shown in Table 1, Table 2, and Table 3.

  The metal laminating film of the present invention is excellent in moldability in can manufacturing and can be used as a laminate film for two-piece cans, and contributes to the industry.

Claims (6)

A thermoplastic polyester film comprising a two-layer structure of a thermoplastic polyester A layer and a thermoplastic polyester B layer, wherein the thermoplastic polyester A layer and the thermoplastic polyester B layer are composed of an ethylene terephthalate component and an ethylene isophthalate component. It consists of a polyester resin composition mainly composed of polyester and having a melting peak in the range of 246 ° C. to 252 ° C., and the thermoplastic polyester A layer contains 0.50 to 1.50 weight of inert particles having a particle size of 3 to 5 μm. %, And the content of inert particles having a thermoplastic polyester B layer having a particle size of 3 to 5 μm is 0.4% by weight or less, on a metal substrate The film that is pasted on the film is remelted by heat above its melting point (so-called remelt treatment) and rapidly The film surface has a dynamic friction coefficient of 0.20 or less with a steel ball loaded with a load of 2 kg in a 150 ° C. environment after being cooled and cooled to a can.
The weight average molecular weight (A) of the thermoplastic polyester film and the weight after the film existing on the metal substrate is remelted by heat above its melting point (so-called remelt treatment) and rapidly cooled to form a can. A film for covering a drawn iron can characterized by having an average molecular weight (B) of 40,000 or more. The weight average molecular weight (A) of the thermoplastic polyester film according to claim 1 and the film existing on the metal substrate are remelted by heat above its melting point (so-called remelt treatment) and rapidly cooled. A film for covering a drawn and ironed can, characterized in that the relationship of the weight average molecular weight (B) after the can processing satisfies the following formula (1).
(B) / (A) ≦ 1 (1)   A film for covering a drawn iron can, wherein the thermoplastic polyester film according to claim 1 contains 0.01 to 1.0% by weight of an antioxidant.   The thermoplastic polyester resin composition according to any one of claims 1 to 3, wherein the alkylene oxide unit having 2 or more carbon atoms derived from the polyoxyalkylene glycol component is 1 with respect to the total acid amount of the polyester resin composition. A film for covering a squeezed iron can characterized by containing -20 mol%.   A film for covering a drawn iron can according to claim 4, wherein the film for covering a drawn iron can is coated on a metal plate.   6. A squeezed iron can made from the film-laminated metal plate according to claim 5.