JP2007261023A - Film for metal sheet laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film which is good in moldability when a film laminate plate is molded and can be molded to produce a metal can having good impact resistance. <P>SOLUTION: In the film for a metal sheet laminate comprising at least two layers of a resin layer (I) in which at least 500 ppm of wax is incorporated in a polyester resin and a resin layer (II) in which a polyester resin of at least 180°C melting point contains a polyamide, the average diameter of the polyamide contained in the resin layer (II) is 0.2-5.0 μm, and a water-dispersible copolyester resin layer (III) is applied on the adhesive surface side to a metal sheet of the resin layer (II). The film is laminated on the metal sheet, melted again by heating at the melting point of the film or above, and then quenched to obtain the laminate. In the laminate, the adhesive strength between the film and the metal sheet is at least 18 N/15 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminated polyester film used for the purpose of preventing corrosion of metal containers such as soft drinks, beer and canned foods, a film laminated metal genus plate obtained by laminating the film on a metal plate, and forming the film laminated metal plate The present invention relates to a metal container. More specifically, a laminated polyester film excellent in laminating property to a metal plate and can manufacturing property (for example, drawing and ironing workability), and a film excellent in flavor and impact resistance obtained by laminating the film on a metal plate. The present invention relates to a laminated metal plate and a metal container formed by forming the film laminated metal plate.

  Conventionally, the inner surface and outer surface of a metal can have been widely coated with a solution in which various thermosetting resins such as epoxy and phenol are dissolved or dispersed in a solvent for the purpose of preventing corrosion. Has been done. However, this thermosetting resin coating method has a drawback in that it takes a long time to dry the paint, so that productivity is lowered and undesired problems such as environmental pollution due to a large amount of organic solvent often occur.

  In order to solve such drawbacks, a method of coating a metal plate with a thermoplastic resin by a melt extrusion method is known. (For example, refer to Patent Document 1). There is also known a method of coating a resin having a two-layer structure of a polyester layer mainly composed of ethylene terephthalate and a layer obtained by blending a polyester mainly composed of ethylene terephthalate and / or ethylene isophthalate with an olefin polymer by a melt extrusion method. ing. (See Patent Document 2). However, in these coating methods, the thickness of both ends of the coating resin is thick, and the both ends of the obtained resin-coated metal plate can be trimmed to use only a relatively uniform central portion as a material for making cans. However, it was not a satisfactory method.

  In order to avoid such a drawback, a method of laminating a cast film of polyester having a melting point of 120 to 260 ° C. on a heated metal plate is disclosed. (See Patent Document 3). However, in this coating method, if the storage period until the cast film obtained is laminated on a metal plate becomes long, the film becomes fragile, and if tension is applied during lamination, the film is easily cut, which is not a substantially satisfactory method. It was.

  By the way, the coating resin used for the metal plate for squeezing and ironing cans has formability that can follow the squeezing and ironing process, adhesion that prevents the resin from peeling off from the metal plate, and impact resistance that can withstand the impact properties during canning. is necessary. However, conventional coating resins for metal cans do not always satisfy such requirements.

  As a method for improving the impact resistance of the polyester resin, for example, a biaxially stretched laminated film comprising a polyester layer mainly composed of polyethylene terephthalate and / or polyethylene isophthalate and a layer in which polyester and a thermoplastic elastomer are blended is used. The method is known. (See Patent Document 4). However, the method described in the above publication does not have sufficient adhesion when laminating a polyester film to a metal plate and moldability for drawing and ironing.

  Further, as a method for further improving the impact resistance of a polyester resin, for example, a method using a biaxially stretched laminated film formed by mixing a crystalline polyester layer, a crystalline polyester, and an olefin polymer is known. (See Patent Document 5). However, the method described in the above publication does not satisfy the flavor property, or the bumping phenomenon (so-called “waki”) due to the heat treatment during can manufacturing.

JP-A-57-203545 JP-A-7-276564 JP-A-7-207039 JP-A-8-156182 Japanese Laid-Open Patent Publication No. 2004-285343

  The object of the present invention is to solve the problems of the prior art. That is, a film-laminated metal plate with good adhesion can be obtained, and when the film-laminated plate is formed, the adhesion and formability (for example, drawing and ironing processability) are good and obtained by molding. The present invention provides a polyester film, a film-laminated metal plate, and a metal container obtained by molding a film-laminated metal plate with good impact resistance.

  An object of the present invention is a resin layer (I) comprising a polyester resin comprising a polyethylene terephthalate unit and a polybutylene terephthalate unit, the weight ratio of which is 20 to 80/80 to 20, and containing a wax of 500 ppm or more. The resin layer (II) is a polyester resin having a melting point of 180 ° C. or higher, and is composed of at least two layers of the resin layer (II), and the polyamide polymer contained in the resin layer (II) An average diameter is 0.2 to 5.0 μm, and a film obtained by applying a water-dispersible copolymerized polyester resin layer (III) to the adhesive surface side of the resin layer (II) with a metal plate. And the water-dispersible copolyester resin layer (III) has a resin thickness of 5 nm to 40 nm, and the laminated polyester film resin The layer ratio of (I) / (II) is 30 to 70/70 to 30, and the film was laminated on a metal plate and rapidly cooled after being remelted by heat above the melting point of the film. This is achieved by a metal plate laminating film characterized in that the adhesion strength between the film and the metal plate later is 18 N / 15 mm or more.

  In this case, it is preferable that the resin layer (I) has a melting point of 200 ° C. or higher and has at least two melting peaks.

  Moreover, in this case, it is preferable that the resin thickness of the water-dispersed copolyester resin layer (III) falls within the range of 5 nm to 40 nm.

  Furthermore, a metal container formed by forming the film-laminated metal plate is also suitable.

  When laminating a film, the polyester film of the present invention has a particularly good adhesion and a can laminateability (particularly, a releasability between a can inner surface film and a processing punch, and an adhesion between a metal plate and the film). A metal plate is obtained, and the metal can obtained by molding the film-laminated metal plate has good impact resistance, and an extremely useful polyester film, film-laminated metal plate, and film-laminated metal plate are molded. It can be said that it is a metal container to obtain.

Hereinafter, the present invention will be described in detail.
The polyester used for the resin layer (I) in the present invention is obtained by mixing and extruding crystalline polyethylene terephthalate / polybutylene terephthalate at a ratio of 20 to 80/80 to 20% by weight. The mixing ratio of crystalline polyethylene terephthalate and polybutylene terephthalate needs to be 20 to 80/80 to 20% by weight. When the polybutylene terephthalate ratio is less than 20% by weight, whitening occurs during the hot water treatment, and when it exceeds 80% by weight, the film-forming property is deteriorated, which is not preferable from the viewpoint of productivity and raw material cost.
In particular, a mixing ratio of 40 to 60/60 to 40% by weight is preferable from the viewpoints of whitening resistance, productivity, and can-making ability.

  The melting point of the polyester used in the resin layer (I) of the present invention needs to be 200 ° C. or higher, and preferably exists in the range of 200 to 260 ° C. If the melting peak is less than 200 ° C., the can-making ability is impaired, and if it exceeds 260 ° C., the balance at the time of melt-extrusion with the resin layer (II) is lost and the film-forming property is lowered. More preferably, it has a melting point of 240 ° C. or higher for the high-temperature side melting peak and 210 ° C. or higher for the low-temperature side melting peak. From the viewpoint of ensuring the above).

  Further, the melting peak needs to have at least two melting peaks. If transesterification proceeds during mixed melt extrusion, warm water whitening and can-making properties (especially punch releasability) decrease, so the reaction is suppressed and the melting peak has two or more melting peaks. Things are necessary. Means for achieving this include lowering the temperature during melt extrusion, or adding an antioxidant and a heat stabilizer to suppress the transesterification reaction.

  In the polyester of the present invention, an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, a pigment, an antistatic agent, a crystal nucleating agent, a lubricant, a lubricant composed of inorganic or organic particles, and the like are blended as necessary. May be.

  The amount of lubricant in the film is not particularly limited, but it is preferably in the range of 0.01 to 2% by weight with respect to the resin layer (I). This is because a lubricant amount of 0.01% by weight or more is preferable so that the film can be smoothly released from punches and dies 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.

  When wax is used as the lubricant, it is a preferred embodiment that it is added in the range of 500 ppm to 2000 ppm. 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.

  As the amount of the inert particles of the polyester, a sample was cut out, a fluorescent X-ray device (device name: ZSX100e) manufactured by Rigaku Corporation was used, each sample was measured from the upper surface and the lower surface with an analysis diameter of 30 mmΦ, and a PET calibration curve was used And converted into the amount of inert particles.

  Examples of the inert inorganic 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 exemplified.

  Examples of the wax include synthetic waxes such as polyolefin wax and polyester wax, and natural waxes such as carnauba wax.

  The average particle diameter 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. On the other hand, if the thickness exceeds 3 μm, the effect of improving the punch releasability is saturated, while the lubricant may fall off due to wear or the film may break when laminated with a metal plate.

  The method for producing the polyester in the present invention is not particularly limited. That is, it can be used even if it is produced by either the transesterification method or the direct polymerization method. Further, it may be produced by a solid phase polymerization method in order to increase the molecular weight. Furthermore, from the point of reducing the amount of oligomers from the polyester resin in the retort treatment etc. that is carried out after filling the contents in the can, it contains oligomers produced by solid phase polymerization under reduced pressure or in an inert gas atmosphere It is preferred to use a low amount of polyester.

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

  As the polyester used in the polyester-based resin composition of the resin layer (II) of the present invention, the above-mentioned polyester can be used as the polyester used in the resin layer (I) of the present invention, however, can manufacturing From the viewpoint of safety, it is not necessary to be a crystalline polyester having a melting point of 200 ° C. or higher. The polyester of the resin layer (I) and the polyester of the resin layer (II) may be the same, but different ones may be used.

  An example of the polyamide-based resin used in the resin layer (II) of the present invention is nylon 6 using ε-caprolactam as a main raw material. In addition, examples of other polyamide resins include polyamide resins obtained by polycondensation of lactams having three or more members, ω-amino acids, dibasic acids and diamines. Specifically, as lactams, in addition to the above-mentioned ω-lactam, enantolactam, capryllactam, lauryllactam, and ω-amino acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononane. An acid and 11-amino undecanoic acid can be mentioned. Dibasic acids include adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecadioic acid, hexadecadioic acid, eicosandioic acid, eicosandienedioic acid, 2, Examples include 2,4-trimethyladipic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and xylylenedicarboxylic acid. Further, diamines include ethylene diamine, trimethylene diamine, tetramethylene diamine, hexamethylene diamine, pentamethylene diamine, undecamethylene diamine, 2,2,4 (or 2,4,4) -trimethyler hexamethylene diamine, Examples include cyclohexanediamine, pisu (4,4′-aminocyclohexyl) methane, and metaxylylenediamine. Polymers obtained by polycondensation thereof or copolymers thereof, such as nylon 6, 7, 11, 12, 6.6, 6.9, 6.11, 6.12, 6T, 6I, MXD6 ( Metaxylene dipanamide 6), 6 / 6.6, 6/12, 6 / 6T, 6 / 6I, 6 / MXD6, etc. can be used. In addition, the above polyamide resins can be used alone or in admixture of two or more.

  In the polyester film after remelting of the present invention, the polyamide polymer blended in the polyester of the resin layer (II) is dispersed in the form of particles, and the average diameter of the dispersed particles is 5.0 μm or less. It is necessary to have both the laminating property, can-making property, and impact resistance of the can, and it is particularly preferably in the range of 0.2 to 3.0 μm. When the dispersion of the polyamide polymer exceeds 5.0 μm, the impact resistance is lowered, which is not preferable.

  In order to make the dispersion diameter of the polyamide polymer within the above range, it can be achieved by selecting the melt-kneading conditions when blending the polyester and the polyamide polymer. The melt-kneading conditions depend on the type and amount of the selected polyester resin and polyamide polymer, but when the melt-blended resin is extruded in layers from a T-die and a film is formed, a twin-screw extruder is used rather than a single screw. It is preferable to use it.

  In the present invention, when the polyester and polyamide resin are blended, the blend ratio needs to be 70:30 to 99: 1. If the polyamide resin is less than 1%, the effect of improving the impact resistance is insufficient, which is not preferable. On the other hand, if the polyamide resin exceeds 30%, the can-making ability (punch releasability) is inferior.

Next, the water-dispersed copolyester resin layer (III) will be described. The water-dispersed copolyester resin of the present invention preferably has a Tg of 40 ° C. or higher and is controlled to have a thickness of 5 nm to 40 nm by so-called coating. If the coat thickness is 5 nm or less, so-called film cracking occurs in the coat layer, and an appropriate resin film cannot be formed. If the coat thickness exceeds 40 nm, peeling or floating occurs during can-making, and the yield decreases, which is not preferable. Regarding this coating treatment, either a stretched film during film formation (in-line) or a film after film formation (off-line) may be used. A water-dispersible polymer is a polymer compound that is insoluble in water but can be dispersed or dissolved in an aqueous solvent. Specific examples include a polymer compound obtained by copolymerizing a monomer component having a hydrophilic group in the molecule. By using such a polymer, excellent adhesion strength with the metal plate can be realized.
In addition, the water-dispersed polymer compound of the present invention can reduce adverse effects on the human body and the environment by not using an organic solvent. Examples of the water-dispersed polymer compound of the present invention include polyester resins copolymerized with monomer components having hydrophilic groups. . The hydrophilic group is, for example, a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, or a derivative or metal base thereof, an ether group, or the like, and a monomer containing these groups in the molecule is copolymerized to form water. It exists in a dispersible state.
Specific examples of the monomer containing a hydrophilic group include polyethylene glycol, polypropylene glycol, glycerin, polyglycerin, 5-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5 (4-sulfophenoxy) isophthalate. Examples thereof include metal salts of sulfonic acid-containing monomers such as acids.
In addition, there is a method in which a copolymerized polyester is graft-polymerized with a pinyl monomer having a hydrophilic group. Examples of the vinyl monomer having a hydrophilic group include a carboxyl group, a hydroxyl group, a sulfonic acid group, an amide group, and the like, and groups that can be changed to a hydrophilic group include an acid anhydride group, a glycidyl group, and a chloro group. Etc. are included. Of these, those having a carboxyl group are preferred. For example, monomers such as acrylic acid, methacrylic acid, maleic acid, and salts thereof.

  In the present invention, the polymer obtained by dry blending or melt-mixing the polyester of the resin layer (I), the polyester of the resin layer (II), and the olefin polymer is melted in a known single-screw or double-screw extruder, respectively. After that, they are merged in the system to form two layers, and a layered molten resin film is obtained by using a T die, or molten resins sent from different flow paths are merged in the T die to be melted in two layers. A resin film is obtained.

  In the present invention, as a cooling and solidification method, a known method in which a resin melted in a layer form from a T die is brought into contact with a rotated cooling roll can be used. When the molten resin is brought into contact with the cooling roll, it is preferable to employ a method of forcibly blowing air, a method of bringing the molten resin into close contact with static electricity, or a method of making the surroundings where the molten resin contacts the cooling roll into a reduced pressure atmosphere.

In the present invention, after cooling and solidifying, it is necessary to carry out 1.3 to 6.0 times longitudinal stretching of the cooled solidified product at a temperature not lower than the glass transition point of the polyester and lower than the cold crystallization temperature. In order to further improve productivity, it is preferable to carry out transverse stretching, and then heat treatment is performed at a relaxation rate of 3% or more at 50 ° C. or more and in the temperature range of -20 ° C. to −80 ° C. of the polyester for 1 to 20 seconds. Get a film. In order to preferably control the so-called heat shrinkage rate of the film, it is necessary to perform heat treatment from the melting point of the film to -20 ° C to -80 ° C.

  Next, both ends of the film are cut and removed, and then cut into a necessary width to obtain a roll-shaped polyester film. In the present invention, it is possible to reuse the raw materials obtained by the method of pressing or melting the remaining film obtained by slicing the both ends and / or the roll film obtained by cutting or removing the above-mentioned film. Is possible. In general, the reusable raw material is preferably used for the resin layer (II) in order to maintain the characteristics of the film. The reuse rate is not particularly limited, but 5 to 50% is preferable.

  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, a surface-treated aluminum plate or an aluminum alloy plate can be used. These metal plates are heated to a melting point of polyester of −20 ° C. or higher and a melting point of + 150 ° C., then laminated using a laminating roll, and subsequently this laminated metal plate is heated at a polyester melting point of + 10 ° C. or higher to melting point + 60 ° C. or lower. After (so-called remelt treatment), water-cooling and / or air-cooling is performed to obtain a film-laminated remelt metal plate.

  The film of the present invention has a two-layer structure of a resin layer (I) and a resin layer (II), and the layer ratio of (I) / (II) is preferably in the range of 70-30 / 30-70. . More preferably, it is 60-40 / 40-60. In high-temperature treatment such as remelt treatment, bumping of the resin layer (so-called flares) is likely to occur, and it is useful to set the layer thickness of the resin layers (I) and (II) to the above ratio in order to suppress this phenomenon. This is because the moldability and the impact resistance can be compatible even if the processing conditions when forming through processing such as ironing become severe.

  In the present invention, the thickness of the film is not particularly limited, but 10 to 50 μm is preferable from the viewpoint of covering effect (rust prevention) and economy.

  The film-laminated metal plate of the present invention is preferably laminated so that the polyester (III) layer side is the metal plate side of the laminated film of the present invention. This is because the polyester (I) layer having releasability constitutes the surface layer of the film-laminated metal plate, so that releasability from the punch can be exhibited at the time of drawing.

The laminated film of the present invention preferably has an adhesion strength between the film after remelting and the metal plate of 18 N / 15 mm or more. This is because if the adhesion strength after the remelt treatment is less than 18 N / 15 mm, floating and peeling are likely to occur.
The adhesion strength between the film and the metal plate is as follows.
(1) Production of Film Laminated Metal Plate After laminating by passing between nip rolls so that the polyester C layer of the polyester laminated film produced above is in contact with the metal plate on a metal plate preheated to 220 ° C., 10 to 40 Rapid cooling in a water bath at 0 ° C. yielded a metal plate laminated with a film.
(2) Remelt metal plate production method (remelting treatment)
The film-laminated metal plate was heated at 270 ° C. for 40 seconds, then air-cooled, and further cooled in water to prepare a remelt metal plate.
(3) Adhesion strength A part of the metal part was dissolved and removed from the remelt metal plate with dilute hydrochloric acid, and only the film was taken out. With this as a trigger, the film / metal plate is peeled off. After sufficiently peeling, a reinforcing material is applied so that the film does not stretch, and cutting is performed to a width of 15 mm. The peel strength of the sample was measured at a tensile speed of 5 mm using a tensile tester.

  In the present invention, the thickness of the water-dispersed resin film on the metal plate is preferably controlled to a thickness of 5 nm to 40 nm. If the coat thickness is 5 nm or less, the coat layer causes so-called film cracking and an appropriate resin film cannot be formed. If it exceeds 40 nm, the remelt plate can be peeled off and floated to reduce the yield. Because.

  Hereinafter, the present invention will be described in more detail based on examples.

[Evaluation methods]
(1) Melting point of polyester After heating and melting the polyester composition at 300 ° C. for 5 minutes, 10 mg of a sample obtained by quenching with liquid nitrogen was used, and 10 ° C. using a differential scanning calorimeter (DSC) in a nitrogen stream. The peak temperature of the endothermic peak accompanying melting when the exothermic / endothermic curve (DSC curve) was measured at a rate of temperature rise per minute was defined as the melting point Tm (° C.).

(2) Inert particle amount of polyester Using a fluorescent X-ray device (device name: ZSX100e) manufactured by Rigaku Corporation for a film cut out as a sample, each sample was measured from the upper surface and the lower surface with an analysis diameter of 30 mmΦ, and a calibration for PET The amount of inert particles was converted using a line.

(3) Average particle diameter of inert particles The coating film sample dried overnight in a vacuum dryer is subjected to ion plasma etching treatment, 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).

(4) Water-dispersed resin layer thickness measurement
The sample cut out while drawing the film was measured by a gravimetric method. In this method, after measuring the weight of the cut sample, the water-dispersed resin layer was wiped off using an arbitrary solvent, the weight of the subsequent sample was measured, and the specific gravity of the resin was set to 1 from the weight difference before and after wiping. It is calculated as the thickness of the water-dispersed resin layer at the time.

(5) Average particle diameter of polyamide-based polymer A film obtained by stretching a sheet obtained by melting and kneading a polyester resin and a polyamide-based polymer with an extruder and extruding into a layer from a T-die by the methods of Examples and Comparative Examples is used as an epoxy resin After being embedded and cured, the specimen was incised by a cryomicrotome in a cross section parallel to each stretching direction to produce an ultrathin section. This was dyed with ruthenium oxide, held at room temperature for 10 minutes, then carbon-deposited and observed with a transmission electron microscope. The average diameter of the dispersed particles was determined by a weighted average of the long diameters using an image analyzer (manufactured by Toyobo, V10).

(6) Production method of laminated aluminum plate A resin film obtained by melt-mixing polyester and polyolefin-based polymer after being melt-mixed with aluminum alloy plate (3004 series alloy plate with a thickness of 0.26 mm) heated to 250 ° C. was laminated. Thereafter, it was rapidly cooled and cured at 40 ° C. or lower to prepare a laminate plate.

(7) Preparation method of remelt aluminum plate The laminate aluminum plate was heated at 275 ° C. for 40 seconds, then air-cooled and then cooled in water to prepare a remelt aluminum plate.

(8) Adhesive strength after remelting A part of the aluminum metal part was dissolved and removed from the remelted aluminum plate with dilute hydrochloric acid, and only the film was taken out. With this as a trigger, the film / aluminum metal plate is peeled off.
After sufficiently peeling, a reinforcing material is applied so that the film does not stretch, and cutting is performed to a width of 15 mm. The peel strength of the sample was measured using a tensile tester at a tensile rate of 5 mm / min.

(9) Releasability of can inner surface resin and processing punch After laminating aluminum plate into cup by drawing, n = 100 can is formed by redrawing and ironing at a speed of 60 cans / min. The degree of buckling occurring in the film was visually observed. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: Buckling has not occurred in the can opening △: 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

(10) Impact resistance A
Ten cans of 7 cm square were cut out from the center part of the barrel wall of the can obtained by making a remelt plate and heating at 280 ° C. for 40 seconds and then rapidly quenching 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

(11) Impact resistance B
A 7 cm square sample was cut out from the center of the barrel wall of a can that was obtained by making a remelt plate and heating it at 280 ° C. for 40 seconds and then rapidly cooling it 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 ○ was evaluated as practical.
○: Corrosion of the convex part is not generated ×: Corrosion of the convex part is generated

(12) Intrinsic viscosity (IV)
It is a value (dl / g) measured at 25 ° C. in orthochlorophenol.

(13) Waki resistance The external appearance of the remelt aluminum plate produced on the conditions of said (7) was observed. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: No bumping occurred ×: Bump occurred

  Next, the types and contents of the polyester and olefin polymer used in Examples and Comparative Examples will be described.

(1) PET: 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, 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 intrinsic viscosity 0.73 polyester (PET) resin was used.

(2) PBT: polybutylene terephthalate (IV = 1.0)
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 performed at 250 ° C. under reduced pressure (1.0 hPa or less). The resulting polyester (PBT, An intrinsic viscosity of 0.85) was used.

(3) PET-I (10): Polyethylene terephthalate / isophthalate (10 mol% repeating unit of ethylene isophthalate, IV = 1.0)
Polyester (PET-I (10), intrinsic viscosity 0.73) obtained by the same method as that for polyethylene terephthalate (PET) except that 90 parts by weight of terephthalic acid and 10 parts by weight of isophthalic acid were used. Was used.

(4) Polyamide A: Nylon 6 (Toyobo, T-814: trade name) was used.
(5) Polyamide B: Polymetaxylylene adipamide (Toyobo, T-600: trade name) was used.
(6) Polyamide C: Polymetaxylylene adipamide (manufactured by Mitsubishi Gas Chemical Company, S6007: trade name) was used.
(7) Polyamide D: Nylon 12 / PTMG copolymer (Toyobo, DA330: trade name) was used.

[Example 1]
Resin layer (I): A material obtained by drying a raw material to which PET / PBT = 40/60 (wt%) as a main raw material and 1000 ppm of polyethylene wax was dried at 100 ° C. for 24 hours was used.
Resin layer (II): obtained by pre-kneading PET-I (10) / polyamide A / polyamide B = 88/3/3 (% by weight) as a main raw material at 270 ° C. using a biaxial vent type extruder. The raw material was dried at 100 ° C. for 24 hours. The resin layers (I) and (II) are each melted at 270 ° C. using a single-screw extruder, and then merged in the flow path, extruded in a layer form from a T-die onto a cooling roll, and an unstretched sheet of laminated resin Got. The unstretched sheet was stretched 3.5 times in the machine direction at a preheating temperature of 80 ° C. and a stretching temperature of 100 ° C., and further stretched by 4.0 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 20 μm was obtained by heat treatment at 0 ° C. for 8 seconds. The ratio of the thickness of each layer of this film was (I) layer / (II) layer = 60/40.

  The film is coated on the resin layer (II) side by a gravure coating method so that the coating layer thickness is adjusted to 10 nm, and dried at 160 ° C. for 8 seconds. did.

  The film was pressure-bonded to a 3004 series aluminum alloy plate (thickness 0.26 mm) heated to 250 ° C. using the resin layer (III) as a joining surface, heated at 275 ° C. for 40 seconds, air cooled, and then rapidly cooled in water. A remelt aluminum plate was obtained.

  After applying the molding lubricant to the remelt aluminum plate thus obtained, it was heated and drawn at a plate temperature of 70 ° C. Next, the temperature of the obtained cup was set to 40 ° C., and ironing was performed at a mold temperature of 80 ° C. to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the melting point, dispersion diameter, adhesion after remelting, can-making ability (releasability of can inner film and punch and degree of scratching of can outer film), crack resistance and impact resistance of polyester. . The laminate plate of this example was excellent in can making ability and resistance to cracking, and the aluminum can of this example was excellent in impact resistance.

[Example 2]
A polyester film having a thickness of 20 μm was obtained in the same manner as in Example 1 except that the layer ratio of the resin layers (I) and (II) was 50/50 and the amount of polyethylene wax added to the resin layer (I) was 800 ppm. Obtained. Next, in the same manner as in Example 1, a remelt aluminum plate was prepared and canned to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the melting point of polyester, dispersion diameter, adhesion after remelting, can-making ability (releasability of can inner surface film and punch and degree of scratching on outer surface film of can), crack resistance and impact resistance. . The laminate plate of this example was excellent in can making ability and resistance to cracking, and the aluminum can of this example was excellent in impact resistance.

[Example 3]
A polyester film having a thickness of 20 μm is obtained in the same manner as in Example 1 except that the raw material of the resin layer (II) is PET-I (10) / polyamide A / polyamide C = 88/3/3 (% by weight). It was. Next, a remelt aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the melting point of polyester, dispersion diameter, adhesion after remelting, can-making ability (releasability of can inner film and punch and extent of scratches on can outer film), crack resistance, and impact resistance. . The laminate plate of this example was excellent in can making ability and resistance to cracking, and the aluminum can of this example was excellent in impact resistance.

[Example 4]
A polyester film having a thickness of 20 μm is obtained in the same manner as in Example 2 except that the raw material of the resin layer (II) is PET-I (10) / polyamide B / polyamide D = 88/3/3 (% by weight). It was. Next, a remelt aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the melting point of polyester, dispersion diameter, adhesion after remelting, can-making ability (releasability of can inner surface film and punch and degree of scratching on outer surface film of can), crack resistance and impact resistance. . The laminate plate of this example was excellent in can making ability and resistance to cracking, and the aluminum can of this example was excellent in impact resistance.

[Example 5]
A polyester film having a thickness of 20 μm was obtained in the same manner as in Example 3 except that the raw material of the resin layer (II) was PET-I (10) / polyamide A = 94/6 (wt%). Next, a remelt aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the melting point of polyester, dispersion diameter, adhesion after remelting, can-making ability (releasability of can inner film and punch and extent of scratches on can outer film), crack resistance, and impact resistance. . The laminate plate of this example was excellent in can making ability and resistance to cracking, and the aluminum can of this example was excellent in impact resistance.

[Comparative Example 1]
A polyester film having a thickness of 20 μm as in Example 1 except that the raw material of the resin layer (II) is PET-I (10) = 100 (% by weight) (a raw material excluding the polyamide resin from Example 1). Got. Next, a remelt aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.

  Polyester melting point, dispersion diameter, adhesion after remelting, can-making ability (releasing properties of can inner surface film and punch and extent of scratches on can outer surface film), crack resistance, impact resistance, steel ball at 50 ° C μ Are shown in Tables 1 and 2. Although the laminate plate of this comparative example was excellent in can-making property and squeeze resistance, it is not preferable because the impact resistance of the aluminum can is poor.

[Comparative Example 2]
A polyester film having a thickness of 20 μm was obtained in the same manner as in Example 3 except that the water-dispersed resin was not applied. Next, a remelt aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the melting point of polyester, dispersion diameter, adhesion after remelting, can-making ability (releasability of can inner surface film and punch and degree of scratching on outer surface film of can), crack resistance and impact resistance. . Although the laminate plate of this comparative example was excellent in the resistance to cracking and impact, it was not preferable because the adhesiveness at the time of can making was poor and the yield was lowered.

[Comparative Example 3]
A polyester film having a thickness of 20 μm was obtained in the same manner as in Example 3 except that the coating thickness of the water-dispersed resin was 50 nm. Next, a laminated aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the melting point, dispersion diameter, remelt adhesion, can-making property (releasability of can inner surface film and punch and degree of occurrence of scratches on can outer surface film), crack resistance and impact resistance of polyester. Although the laminate plate of this comparative example was excellent in the resistance to cracking and impact, it was not preferable because the adhesiveness at the time of can making was poor and the yield was lowered.

[Comparative Example 4]
A polyester film having a thickness of 20 μm was obtained in the same manner as in Example 3 except that the raw material of the resin layer (I) was changed to PET-I (10) = 100 (% by weight). Next, a laminated aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the melting point, dispersion diameter, remelt adhesion, can-making property (releasing properties of can inner film and punch and extent of scratches on can outer film), crack resistance, and impact resistance of polyester. When the laminate plate of this comparative example was canned, the can inner surface film was poorly stretched and a canned product worthy of evaluation could not be obtained.

[Comparative Example 5]
A polyester film having a thickness of 20 μm was obtained in the same manner as in Example 3 except that the raw material for the resin layer (I) was changed to PET / PBT = 10/90 (wt%).

  The film of this comparative example had very poor film formability, and many breaks occurred during stretching, and a stable film film could not be secured.

[Comparative Example 6]
A polyester film having a thickness of 20 μm was obtained in the same manner as in Example 3 except that the layer ratio of the resin layer (I) to the resin layer (II) was 20/80. Next, a laminated aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.

  Tables 1 and 2 show the melting point, dispersion diameter, remelt adhesion, can-making property (releasability of can inner surface film and punch and degree of occurrence of scratches on can outer surface film), crack resistance and impact resistance of polyester. The laminate plate of this comparative example had a bumping (so-called flaky) phenomenon at the time of remelting, and a can-made product worthy of evaluation could not be obtained.

  The results are shown in Tables 1 and 2.

  When laminating a film, the polyester film of the present invention has a particularly good adhesion and a can laminateability (particularly, a releasability between a can inner surface film and a processing punch, and an adhesion between a metal plate and the film). A metal plate is obtained, and the metal can obtained by molding the film-laminated metal plate has good impact resistance, and can be used for extremely useful polyester-based films, contributing greatly to the industry. It is.

Claims (4)

  A resin layer (I) comprising a polyester resin comprising a polyethylene terephthalate unit and a polybutylene terephthalate unit, the weight ratio of which is 20 to 80/80 to 20, and containing a wax of 500 ppm or more, and a melting point of 180 ° C. or more The polyester resin is composed of at least two layers of a resin layer (II) characterized by containing a polyamide polymer, and the average diameter of the polyamide polymer contained in the resin layer (II) is 0.2. The film is obtained by applying a water-dispersible copolymerized polyester resin layer (III) to the adhesive surface side of the resin layer (II) with the metal plate, and the water dispersion The resin thickness of the type copolyester resin layer (III) is 5 nm to 40 nm, and the laminated polyester film resin layer (I) / ( The layer ratio of I) is 30 to 70/70 to 30, the film is bonded to a metal plate, remelted by heat equal to or higher than the melting point of the film, and rapidly cooled. A metal plate laminating film, wherein the adhesion strength of the metal plate is 18 N / 15 mm or more.   2. The metal plate laminating film according to claim 1, wherein the resin layer (I) has a melting point of 200 ° C. or higher and has at least two melting peaks.   The metal plate laminating film according to claim 1 or 2, wherein the water-dispersed copolyester resin layer (III) has a Tg of 40 ° C or higher.   A metal container formed by molding the film-laminated metal plate according to claim 3.