JP4784071B2 - Film and film roll for drawing and ironing can coating, film-coated metal plate for drawing and ironing can using the same, and film-coating drawing and ironing can - Google Patents

Description

  The present invention relates to a thermoplastic resin film suitably used for a film-coated metal plate used for a drawing / ironing can. More specifically, the present invention relates to a thermoplastic resin film for metal plate laminating and molding excellent in moldability such as drawing and ironing, and relates to a film roll obtained by winding the thermoplastic resin film into a roll. The present invention also relates to a film-coated metal plate for a drawing / ironing can on which the thermoplastic resin film is bonded, and to a film-coated drawing / ironing can obtained by molding the coating film-coated metal plate.

  As a method for preventing corrosion of the inner wall surface and the outer wall surface of the metal can, there is a method of covering the inner wall surface and the outer wall surface of the metal can with a thermoplastic resin film. For example, a polyester film for coating a metal material for canned food is disclosed (see Patent Document 1 below).

  The polyester film is excellent in 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 opening portions of the cylinder, the coated metal plate is formed by winding or the like. When processing or transporting a metal plate coated with a film (hereinafter referred to as “film-coated metal plate”), scratches on the film surface are rarely generated, reducing the commercial value. That's it.

  In addition, the polyester film has excellent scratch resistance at the time of squeezing and has a small amount of oligomer elution when heated after hot water treatment such as retort treatment after filling foods after making cans. It is excellent as a film covering a wall surface.

  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-coated metal plate is only formed into a cylindrical shape, but in the case of a two-piece can, the film-coated metal plate is formed by drawing and ironing. Therefore, in order to apply to a two-piece can, it is necessary that the film has good formability such that the film is formed following the formation of the metal plate and has excellent adhesion to the metal plate. If the moldability is insufficient or the film has insufficient adhesion to the metal plate, the film may be peeled off from the metal plate, so-called delamination phenomenon occurs, or the film is produced during the production of the container part of a two-piece can Such as tearing occurs. In order to apply to a two-piece can, a film that can withstand processing with a high plate thickness reduction rate of the can wall represented by the following formula 1 is required.
Sheet thickness reduction rate (%) = ((original plate thickness−can wall thickness) / original plate thickness)) × 100

  Furthermore, in the drawing process, the film-coated metal plate is processed into a container shape while repeating the lowering and raising of the deep drawing forming punch, so that the film coated on the inner wall surface of the container can be released from the punch. In the same manner, a film coated on the outer wall surface of the container is required to release from the die. That is, in order to obtain good canability in a coating film for a two-piece can, it is necessary to have conflicting elements of adhesion and releasability. In this respect, the polyester disclosed in the above-mentioned Patent Document 1 The film was insufficient for use as a coating film for a two-piece can.

  In addition, if the film is torn and the film breaks due to impact from the outside during the distribution stage after food filling or during low temperature storage, the quality of the food in the container will be significantly impaired. Impact resistance and corrosion resistance (these are collectively referred to as dent resistance) are required. That is, in the covering film for two-piece cans, it is necessary to make both the above-mentioned can-making property and dent resistance compatible. In this respect, the polyester film disclosed in the above-mentioned Patent Document 1 is for two-piece cans. It was insufficient for use as a coating film.

Furthermore, in the production process of the film-coated metal plate, when using a metal plate wound up in a roll shape and a film roll wound up in the same roll shape and covering both continuously, the entire length of the film roll is covered. Therefore, it is necessary to maintain the above characteristics.
JP-A-7-227946

  The object of the present invention has been made in view of such circumstances, and has good moldability and excellent adhesion, which can be applied as a metal plate, particularly a metal plate coating film for a so-called two-piece can. Another object of the present invention is to provide a film roll that maintains the above-mentioned characteristics over the entire length of the wound coating film. Also provided are a film-coated metal plate for a squeezing / ironing can excellent in molding process stability, and a film-coated squeezing / ironing can excellent in appearance characteristics and impact resistance, which is coated with the squeezing / ironing can coating film. There is.

In order to achieve the above object, the present invention has the following configuration.
(1) A covering film in which an adhesive resin layer made of a thermoplastic resin is provided on a base film made of a thermoplastic resin, wherein the base film and the adhesive resin layer are made of a thermoplastic polyester resin, The base film has two layers of A layer / B layer, and the polyester constituting the A layer of the base film is a polyester mainly composed of mixed polyester in which polyethylene terephthalate and polybutylene terephthalate are blended. Among the polyester raw material components of the polyester constituting the B layer of the film, 2 to 15 mol% of the total acid component is an aliphatic dicarboxylic acid having 10 or more carbon atoms, and the adhesive resin layer is the surface of the B layer of the base film the water-dispersible polymer compound composed of a thermoplastic polyester resin is characterized by formed by applying the Furthermore, when 100 points were cut out as a sample at 100 m intervals in the longitudinal direction of the film roll while pulling out the covering film from a film roll formed by winding up the covering film by 10,000 m or more, 100 points of the cut sample A film for covering drawn and ironed cans, wherein the thickness of the adhesive resin layer falls within a range of 30 nm ± 20 nm.
(2) A film roll for covering a squeezing / ironing can, wherein the film for covering the squeezing / ironing can according to (1) is wound in a roll shape at least 10,000 m or more.
(3) A film covering metal for a drawing / ironing can, characterized in that the film for covering a drawing / ironing can according to (1) is coated on a metal plate so that the adhesive resin layer side is in contact with the metal plate. Board.
(4) A film-covered drawn and ironed can obtained by molding and processing the film-coated metal plate according to (3) .

  The squeezing / ironing can coating film of the present invention is a squeezing / ironing can coating film having good formability and excellent adhesion, particularly when used as a coating film for a two-piece can. Further, the base film has a two-layer configuration of polyester A layer / polyester B layer, and 2 to 15 mol% of the total acid component among the polyester raw material components of the polyester B layer is an aliphatic dicarboxylic acid having 10 or more carbon atoms, By setting the polyester B layer to be on the side of the surface to be bonded to the metal plate, it is possible to obtain a film for covering a drawn and ironing can having better moldability and excellent adhesion. Furthermore, the film-coated metal plate for drawing and ironing can coated with the film for covering the drawing and ironing can of the present invention is excellent in molding process stability, and is a film obtained by molding the film-coated metal plate for drawing and ironing can of the present invention. The coated drawing / ironing can has excellent appearance characteristics and impact resistance.

  The drawn / ironing can coating film of the present invention is a coating film in which an adhesive resin layer made of a thermoplastic resin material is provided on one surface of a base film made of a thermoplastic resin material.

  The thermoplastic resin material used for the base film of the coating film of the present invention is not particularly limited, but it is preferable to use a thermoplastic polyester resin from the viewpoint of heat resistance and aroma retention. Among them, it is particularly preferable to use a mixed polyester containing crystalline polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) as a main component.

  When the above-mentioned mixed polyester of PET and PBT is used as the thermoplastic resin material used for the base film of the coating film of the present invention, PET / PBT = 20-80 / 80-20% by weight, especially PET / PBT = 40-60. It is preferable to blend at a ratio of / 60 to 40% by weight. If the PBT ratio is less than 20% by weight, the coating film may be whitened unevenly by hot water treatment in the food and beverage filling process, and if it exceeds 80% by weight, the whitening prevention described above may occur. This is because the function is saturated and there is a possibility that it may be economically disadvantageous in terms of productivity and raw material cost.

  As the component constituting the thermoplastic resin, it is preferable to use a mixed polyester of PET / PBT as described above, but it is not limited to this and is within a range not impairing the properties of the coating film of the present invention. Any dicarboxylic acid component / diol component may be used as a raw material component of the polyester.

  For example, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, other oxycarboxylic acids, and alicyclic dicarboxylic acids are used as the dicarboxylic acid component. be able to.

  The diol component includes ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, neopentylglycol and other aliphatic glycols, cyclohexanedimethanol and other alicyclic glycols, bisphenol A, bisphenol S and other aromatic glycols. Can be used.

  In the thermoplastic polyester resin used for the base film of the coating film of the present invention, it is preferable that the melting peak exists in the range of 200 ° C to 260 ° C. This is because if the melting peak is less than 200 ° C., the can-making property and heat resistance may be impaired, and if it exceeds 260 ° C., the film formability may be lowered. The melting peak is more preferably 220 ° C to 260 ° C. This is because when the can-making speed is increased, the yield may decrease near 200 ° C. The melting peak is observed as an endothermic peak accompanying melting when an exothermic / endothermic curve (DSC curve) is measured using a differential scanning calorimeter (DSC). There may be a plurality of the melting peaks. In order to make the melting peak within the above range, there are methods such as controlling the resin temperature during melt extrusion to suppress the transesterification reaction.

  Further, when the mixed polyester of PET / PBT is used, endothermic peaks (melting peaks) associated with melting of PET and PBT are observed. Each melting peak in this case is also preferably within the range of 200 ° C to 260 ° C.

  Moreover, in the said thermoplastic polyester resin, it is preferable that the crystallization peak temperature (Tc) at the time of temperature rise exists in the range of 70-100 degreeC. If Tc exceeds 100 ° C., crystal whitening is likely to occur during hot water treatment, and if Tc is less than 70 ° C., film formability may deteriorate. However, when the base film has a two-layer configuration of A layer / B layer as will be described later and the B layer is handled as a layer in contact with the metal plate, it is not necessary to apply the above temperature range to the B layer. Rather, it is preferable in terms of formability and adhesion that Tc exceeds 100 ° C.

  The base film of the coating film of the present invention preferably contains inert particles, crosslinked polymer particles, or wax as a lubricant.

  As the inert particles, silica, alumina, kaolin, clay, titanium oxide, calcium phosphate, calcium carbonate, lithium fluoride, barium sulfate, carbon black and the like are preferable.

  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.

  Examples of the wax include synthetic waxes such as polyolefin wax and polyester wax, and natural waxes such as carnauba wax. For example, polyethylene wax is preferably used. Use of a wax is preferable because the effect of the lubricant described later can be obtained with a minimum amount.

  The average particle size of the particulate lubricant is preferably 1 to 3 μm. This is because if it is less than 1 μm, the effect of improving punch releasability cannot be exhibited. On the other hand, if the thickness exceeds 3 μm, the effect of improving punch releasability is saturated. On the other hand, the lubricant is likely to fall off due to wear, or the film may be broken during coating with a metal plate.

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

  In addition, the base film of the squeezing / ironing can coating film of the present invention has a low content of low molecular weight compounds from the viewpoint of antifouling property in a can manufacturing line and aroma retention in the case of use on the inner surface of a can. The more preferable. When polyester is used as the base film, the content of the oligomeric cyclic trimer including the ethylene terephthalate cyclic trimer in the base film is preferably 0.7% by weight or less. This is for suppressing oligomer precipitation from a film and making a can-making line hard to be contaminated. In addition, when used on the inner surface of a can, when food products such as beverages are filled and heat treatment such as retort treatment is performed, a large amount of oligomers are eluted, and the oligomers migrate to foods, resulting in the taste of food. This is to prevent adverse effects on flavors and flavors.

  The method for reducing the oligomer cyclic trimer content to 0.7% by weight or less is not particularly limited. [1] A method of extracting and removing the cyclic trimer from the film with water or an organic solvent after film formation, [2] Examples include a method of forming a film using a polyester having a small cyclic trimer. Of these, the method [2] is economical and preferable.

  In the above method [2], the method for producing a polyester having a low cyclic trimer content is not limited, and the solid phase polymerization method; after the polymerization, by heat treatment under reduced pressure or by extraction with water or an organic solvent, And a method for extracting and removing the polymer; and a method combining these methods. In particular, after producing a polyester having a low cyclic trimer content by solid phase polymerization, the method of extracting the obtained polyester with water to further reduce the cyclic trimer is the cyclic trimer in the film forming step. It is most preferable because the amount of body produced can be reduced.

  The polyester used for the base film of the coating film of the present invention is synthesized by a conventionally known method such as a direct esterification method in which a dicarboxylic acid and a diol are directly reacted; and a transesterification method in which a dicarboxylic acid dimethyl ester is reacted with a diol. Is done. 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 also preferable from the viewpoint of reducing the content of the cyclic trimer as described above. The polyester synthesized in this manner may be included in the film in a single type or in a mixture of two or more types.

  In addition to the above compounds, the polyester includes inorganic fine particles, incompatible thermoplastic resins, antioxidants, thermal stabilizers, ultraviolet absorbers, plasticizers, pigments, antistatic agents, lubricants, if necessary. Additives such as crystal nucleating agents may be included. There are various types of heat stabilizers such as hindered phenols and phosphorus, and it is a particularly preferred embodiment that these are contained alone or in combination in an amount of 0.01 to 10% by weight.

  The intrinsic viscosity of the polyester when the various components are mixed is preferably in the range of 0.6 to 1.2 dl (deciliter) / g. If the intrinsic viscosity is less than 0.6 dl / g, the mechanical properties of the resulting film may be deteriorated. Even if it exceeds 1.2 dl / g, the effect of the mechanical properties does not change, and the production of the raw material polyester In many cases, it also becomes economically disadvantageous because of the decline in performance.

  The polyester film as the base film of the present invention is not limited to use by laminating another layer, in addition to being used as a single layer film having the above-described configuration. That is, a single-layer film having the above-described configuration may be a two-layer configuration of A layer / B layer, with A layer and another layer to be laminated as B layer. The lamination method is not particularly limited, and may be manufactured by a multilayer extrusion method, or may be manufactured by an extrusion coating method or the like. In particular, it is a preferred embodiment that the polyester raw material component of the B layer is configured as described later and that the B layer is treated as a layer in contact with the metal plate, so that the B layer can function as an impact-resistant absorption layer. In this case, the above-mentioned inert particles, crosslinked polymer particles, or wax as a lubricant is mixed in the A layer, and the adhesive resin layer is provided on the B layer. In addition, the above description regarding the base film applies to the A layer.

  In the coating film of the present invention, when the two-layer constitution of A layer / B layer as described above is used, 2 to 15 mol% of the total acid component in the polyester raw material component of the B layer is carbon A polyester composed of several tens or more aliphatic dicarboxylic acids is preferable. Examples of the aliphatic dicarboxylic acid having 10 or more carbon atoms include decanedicarboxylic acid and dimer acid. The resin used as the base is not particularly limited, but it is preferable to use polyethylene terephthalate as a main component from the viewpoint of heat resistance and fragrance retention. For example, a mixed polyester resin comprising terephthalic acid and the above-mentioned dimer acid as a dicarboxylic acid component and a copolymerized polyethylene terephthalate (copolymerized PET) using ethylene glycol as a diol component can be used. Specifically, a dimer in which the dicarboxylic acid component in the raw material component is composed of terephthalic acid units (a) mol%, dimer acid (36 carbon atoms) units (b) mol%, and the diol component is 100 mol% ethylene glycol units. It is preferable to use a mixed polyester resin obtained by mixing acid-copolymerized PET (c) wt% and the remaining PET. Here, a, b and c may be set so that a + b = 100 and b × c ÷ 100 = 2 to 15. For example, when a = 90, b = 10 and c = 60, The proportion of the aliphatic dicarboxylic acid having 10 or more carbon atoms in the polyester raw material component is 6 mol% of the total acid component.

  Moreover, when it is set as the said 2 layer structure of A layer / B layer, it is preferable that the layer ratio of the polyester A layer and the polyester B layer is 30-70 / 70-30 weight%, Most preferably, it is 50-60 / 50 The ratio is ˜40% by weight. If the ratio of the polyester B layer is less than 30% by weight, the polyester B layer as an impact-resistant absorption layer becomes thin, so that the effect of improving the impact resistance at low temperatures (about 5 ° C.) may not be obtained. On the other hand, if it exceeds 50%, the polyester B layer becomes too thick, and the film formability and heat resistance may deteriorate.

  In the said polyester B layer, it is preferable that the melting peak mentioned above exists in the range below 200 degreeC or more and below the melting peak of the polyester A layer. If the melting peak is less than 200 ° C., the canability and heat resistance may be impaired as in the case of the A layer, and if the melting peak exceeds the melting peak of the polyester A layer, the film is laminated or a metal plate. This is because excessive heat is applied to the polyester A layer at the time of coating, and the film strength is lowered, which may cause damage during film production and tearing when the film is coated on metal.

  As the component constituting the polyester B layer, as described above, the polyester raw material component preferably contains aliphatic dicarboxylic acid having 10 or more carbon atoms in an amount of 2 to 15 mol% of the total acid component, and the base resin is polyethylene terephthalate. However, the present invention is not limited to this, and any dicarboxylic acid component / diol component may be used as long as the properties of the coating film as a base film are not impaired. Good.

  Examples of the dicarboxylic acid component in the polyester raw material component constituting the polyester B layer include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, In addition, oxycarboxylic acid, long chain aliphatic dicarboxylic acid, and alicyclic dicarboxylic acid can be used.

  The glycol component includes aliphatic glycols such as ethylene glycol, propanediol, butanediol, pentanediol, hexanediol and neopentylglycol, alicyclic glycols such as cyclohexanedimethanol, and aromatic glycols such as bisphenol A and bisphenol S. Can be used.

  In addition, the conventional method can be used as a method for synthesizing the polyester constituting the polyester B layer, and other additives can be contained in the polyester composition as necessary within the range satisfying the above requirements. The polyester composition The intrinsic viscosity and the like are the same as those described for the base film.

  The base film of the drawn / ironing can coating 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 it may be carried out by a method of stretching in the reverse order. 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, it is not restricted at all to perform corona discharge treatment or predetermined coating treatment on one side or both sides of the base film before or after the stretching step.

  As described above, in order to obtain good canability in the film for covering a two-piece can, there are conflicting elements such as adhesion to a metal plate and releasability from a punch for forming and a die. There is a need. In the coating film of the present invention, adhesion is obtained by providing an adhesive resin layer on the side in contact with the metal plate.

  The adhesive resin layer in the present invention is an adhesive resin layer made of a thermoplastic resin, and preferably an adhesive resin layer made of a thermoplastic polyester resin. Furthermore, the adhesive resin layer is preferably formed by applying a water-dispersed polymer compound. Here, the water-dispersed polymer compound refers to 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 compound, excellent adhesion strength with the metal plate can be realized. Moreover, the influence on a human body and an environment can be reduced by not using an organic solvent.

  Examples of the water-dispersed polymer compound include polyester resins obtained by copolymerizing a monomer component having a hydrophilic group. The hydrophilic group is, for example, a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, or a derivative or metal base thereof, an ether group, or the like, and a monomer containing these groups in the molecule is copolymerized to form water. It exists in a dispersible state.

  Specific examples of the monomer containing a hydrophilic group include polyethylene glycol, polypropylene glycol, glycerin, polyglycerin, 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 the copolymer 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 addition, about the said adhesive resin layer, it is preferable that a glass transition temperature (Tg) is 60 degreeC or more.

  The adhesion between the coating film and the metal plate is influenced by various factors, but also depends on the thickness of the adhesive resin layer. Therefore, controlling the thickness of the adhesive resin layer within a certain range is an important factor for obtaining stable adhesion of the coating film to the metal plate.

  The adhesive resin layer is coated on the base film by, for example, a gravure coating method. When the base film has a two-layer structure of A layer / B layer, it is coated on the B layer side. In order to obtain stable adhesion of the coating film to the metal plate, the adhesive resin layer needs to be controlled to a thickness of 30 nm ± 20 nm. Specifically, it was cut out when 100 points were cut out as a sample at 100 m intervals in the longitudinal direction of the film roll while pulling out the covering film from a film roll wound up by 10,000 m or more of the covering film. It is necessary that the thickness of the adhesive resin layer of 100 samples is in the range of 30 nm ± 20 nm.

  When the thickness of the adhesive resin layer is less than 10 nm, sufficient adhesion to the metal plate cannot be obtained, and peeling may occur without being able to withstand the molding process at the time of can making, while the thickness is 50 nm. Even if it exceeds, performance will not change and it will be disadvantageous in terms of cost. Furthermore, if the coating thickness changes in the longitudinal direction of the film roll, the stability during the molding process is lowered, which is not preferable.

  The method for controlling the thickness of the adhesive resin layer to 30 nm ± 20 nm is not particularly limited, but the thermoplastic polyester resin used as the adhesive resin layer is dispersed in an aqueous solvent to form an emulsion, and the concentration is measured. And a method of applying to the base film by a gravure coating method while controlling. In addition, regarding the coating treatment of the adhesive resin layer, either a stretched film during the formation of the base film (in-line) or a treatment after the film formation (off-line) may be performed.

  The film roll for covering a drawn and ironed can according to the present invention is formed by winding the covering film in a roll shape at least 10,000 m or more on at least one surface of a metal plate with the adhesive resin layer side as a covering surface. It can be suitably used as a coating film for coating and obtaining a metal plate for drawing and ironing cans.

  The film-coated metal plate for drawing and ironing can of the present invention is obtained by coating the metal plate with the film for covering drawing and ironing can of the present invention. The method for coating the drawing / ironing can coating film with the metal plate is not particularly limited, and for example, a dry laminating method, a thermal laminating method, or the like can be employed. Specifically, the metal plate is heated above the glass transition point of the adhesive resin layer of the coating film, and the coating film is brought into contact with the surface of the metal plate so that the adhesive resin layer is in contact with the metal plate. Pass between nip rolls. Subsequently, it coats by carrying out rapid hardening at 10-40 degreeC. After passing through the nip roll, if necessary, it may be remelted (remelted) above the melting point of the base film.

  Further, the drawing / ironing can coating film of the present invention may be coated on one side or both sides of the metal plate. In the case of double-sided coating, the film may be coated simultaneously or successively. Good.

  In the present invention, when the base film to be used is a biaxially stretched film and the film-coated metal plate is applied to a two-piece can, in order to remove the molecular orientation of the polyester after coating, the melting point of the polyester constituting the base film is exceeded. It is preferable to perform a remelting (remelting) treatment that is heated at Immediately after remelting, it is preferable to perform rapid cooling by using cooling water or the like. This is because, after remelting, crystallization is likely to occur during the process of cooling and solidifying the polyester only by decooling, for example, by allowing it to cool to the air, and the polyester is subjected to drawing and ironing in the subsequent can manufacturing process. This is because it becomes difficult to follow the deformation due to the processing, and as a result, it becomes impossible to make cans.

  The degree of molecular orientation by X-ray observation after the remelt treatment is 10% or less, which can be said to be substantially non-oriented. In other words, biaxially stretched films in which the polyester is oriented are difficult to plastically deform and difficult to stretch, making it difficult to carry out the drawing process for forming the container part. The delaminating phenomenon of peeling from the plate is likely to occur, and the possibility of tearing, scraping, etc. increases. On the other hand, if it is substantially non-oriented, it can follow the deformation of the coated metal plate, so that it can be molded with plastic deformation of the metal for a two-piece can without delaminating or tearing. it can.

  In the present invention, a surface-treated steel plate such as tin-free steel, an aluminum plate or an aluminum alloy plate, or a surface-treated aluminum plate or aluminum alloy plate can be used as the metal plate. The thickness is not particularly limited, but is preferably 100 to 500 μm, more preferably 150 to 400 μm, from the viewpoint of economical efficiency represented by the cost of materials, molding processing speed, and the like, while ensuring the material strength. is there.

  In the present invention, the thickness of the coating film on the metal plate is not particularly limited, but 10 to 50 μm is a preferred embodiment from the viewpoint of coating effect (rust prevention), impact resistance, and economical efficiency. If the coating film thickness is less than 10 μm, there is a high possibility that impact resistance will not be obtained, and if it exceeds 50 μm, it is an excessive quality and is often economically undesirable.

  As described above, the film for drawing and ironing can coating of the present invention covers at least one surface of a metal plate with the adhesive resin layer side as a coating surface to form a metal plate for drawing and ironing can. It can be suitably used when a metal plate for cans is made into a squeezed / ironing can.

  The film-coated drawing / ironing can of the present invention is a metal can formed by appropriately forming a film-coated metal plate for drawing / ironing can coated with the film for drawing / ironing coating of the present invention, the shape of the metal can, The method for forming the metal can is not particularly limited. Specifically, a so-called three-piece can in which the top cover is wound and filled with contents, as well as a two-piece can formed by drawing a metal plate to form a container portion can be exemplified.

  The film-coated drawn and ironed can of the present invention may be a three-piece can as described above, but it is a two-piece can formed by forming and processing the film-coated metal plate for drawn and ironed can of the present invention. Is preferred.

  In the film-coated drawn / ironing can of the present invention, the drawn / ironed can coating film of the present invention may be formed so as to be on the inner wall surface side of the metal can, or may be formed on the outer wall surface side. Also good.

  In addition, when performing drawing and ironing, if necessary, a lubricant may be applied to the film surface with which the processing punch comes into contact.

  The film-coated drawing / ironing can of the present invention may be subjected to printing or the like as necessary, and may be subjected to re-melt treatment after the can-making process or printing process.

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

Various evaluation methods in the present invention are shown below.
(1) Thermal characteristics of polyester 10 mg of a sample obtained by partially cutting the unstretched base films prepared in Examples 1 and 2 and Comparative Examples 1 and 2, heating and melting at 300 ° C. for 5 minutes, and then rapidly cooling with liquid nitrogen When the exothermic / endothermic curve (DSC curve) was measured at a rate of temperature increase of 10 ° C./min using a differential scanning calorimeter (DSC) in a nitrogen stream, The melting point was Tm (° C.), and the apex temperature (crystallization peak temperature) at the temperature rising crystallization was Tc (° C.).
(2) Measurement of average thickness of adhesive resin layer and variation in thickness At least 10,000 m or more of the coating film prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was wound into a roll to form a film roll. While pulling out the coating film from the film roll, samples were cut out at 100 m intervals in the longitudinal direction of the film roll, and 100 points of the cut out samples were measured by a gravimetric method. After measuring the weight of the cut sample, the adhesive resin layer was wiped off using an arbitrary solvent, the weight of the subsequent sample was measured, and the specific gravity of the adhesive resin was set to 1 from the weight difference before and after wiping. It is calculated as the thickness of the adhesive resin layer at the time. Evaluation criteria were set as follows for the average thickness and the variation in thickness, and ○ was evaluated as practical.
[Average thickness]
○: 10 to 50 nm
X: When less than 10 nm or exceeds 50 nm [Thickness variation]
○: 20 nm or less ×: When exceeding 20 nm (3) Releasability between can inner surface resin and processing punch (can manufacturing ability)
The remelt aluminum plates prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were canned at n = 10, and the degree of buckling occurring at the upper part of the molded can was visually observed. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: No buckling at the can opening ×: Buckling occurred at 1/3 or more of the circumference of the can opening (4) Impact resistance (dent resistance)
A 7 cm square sample is cut out from the center part of the body wall of the can obtained by making the remelt aluminum plate prepared in Examples 1 and 2 and Comparative Example 2 heated at 280 ° C. for 40 seconds and then rapidly cooled in water. A weight (600 g) having a tip diameter of 10 mmφ was dropped from a height of 10 cm to the surface of this sample that was not evaluated, and an impact was applied. Subsequently, the surface to be evaluated of the portion subjected to impact was immersed in 7% dilute hydrochloric acid, and the corrosion state of the portion was visually observed after 3 days. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: No corrosion occurred ×: Corrosion occurred

In addition, the raw material components were confirmed as follows.
(5) Composition ratio of copolymer polyester About 5 mg of the polyester composition prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was added to 0.7 ml of a mixed solution of deuterated chloroform and trifluoroacetic acid (9/1; volume ratio). It melt | dissolved and calculated | required using 1H-NMR (the product made from varian, UNITY50).

[Example 1]
[Production of polyester film (base film)]
The base film of Example 1 has a two-layer configuration of polyester A layer / polyester B layer.
Polyester A layer: Polyethylene terephthalate (PET) synthesized by solid phase polymerization using terephthalic acid as the dicarboxylic acid component, ethylene glycol as the diol component, terephthalic acid as the dicarboxylic acid component, 1,4-butanediol as the diol component Using a mixed polyester prepared by blending polybutylene terephthalate (PBT), which was also synthesized by the solid phase polymerization method, in a ratio of PET / PBT = 40/60% by weight, the base resin was used to form agglomerated silica particles (average particle size) A polyester composition A1 containing 0.3% by weight (diameter of 1.5 μm) and 3% by weight of a heat stabilizer, having an intrinsic viscosity of 0.7 dl / g and an ethylene terephthalate cyclic trimer of 0.4% by weight was used.
Polyester B layer: 60% by weight of dimer acid copolymerized PET comprising 90% by mole of dicarboxylic acid component, 10% by mole of dimer acid unit having 36 carbon atoms, and 100% by mole of diol component of ethylene glycol unit Polyester composition B1 in which 16% by weight of PET and 24% by weight of PBT were mixed was used. The composition ratio of the copolyester was confirmed using the above-mentioned 1H-NMR (manufactured by varian, UNITY 50).
The ratio of the aliphatic dicarboxylic acid having 10 or more carbon atoms (= dimer acid) in the raw material component in the polyester composition B1 of Example 1 is 10 because b and c described above are b = 10 and c = 60, respectively. × 60 ÷ 100 = 6, that is, 6 mol% of the total acid components.
The polyester composition A1 and the polyester composition B1 of Example 1 were each dried with a paddle dryer, supplied to a funnel-shaped hopper directly above a single screw extruder, and melted in the extruder. Each melt was extruded from each extruder to a ratio of polyester composition A1 / polyester composition B1 = 60/40% by weight, merged in a die, extruded, cooled rapidly, and unstretched two-layer base A film was obtained. A portion of this unstretched bilayer base film was cut out and the thermal properties were measured. The results are shown in Table 1. The obtained unstretched base film was stretched 3.3 times in the machine direction at a preheating temperature of 65 ° C. and a stretching temperature of 100 ° C., and further in the transverse direction at a preheating temperature of 65 ° C. and a stretching temperature of 90 ° C. After stretching 4.0 times, heat treatment was performed at 160 ° C. for 8 seconds, relaxation treatment of 4% was performed at 160 ° C., and biaxial with a thickness of 20 μm (polyester A layer thickness 12 μm, polyester B layer thickness 8 μm) A stretched bilayer base film was obtained. Thereafter, a coating liquid (Toyobo Co., Ltd.) made of a thermoplastic polyester resin whose concentration is adjusted to a thickness of 30 nm by the gravure coating method on the polyester B layer side of the two-layer base film. (Trade name; Vironal dispersed in a solvent) was coated and dried at 160 ° C. for 8 seconds to obtain a film for covering a drawn and ironed can of Example 1. The obtained film for drawing and ironing can coating was wound up in a roll shape of 10,000 m or more to obtain a film roll of the present invention. A sample was cut out from the film roll by the method described above, and the thickness of the adhesive resin layer was measured by a weight method. The average thickness of the adhesive resin layer was 30 nm as set. Further, the variation in the thickness of the adhesive resin layer of 100 samples was 8 nm at the maximum. The results are shown in Table 1.
[Production of film-coated metal sheet]
The above-mentioned film for squeezing and ironing can coating is pasted on both sides of the preheated aluminum plate so that the adhesive resin layer side is in contact with the metal plate, passed between nip rolls and coated while pressing, and then heat treated. Immediately after that, it was rapidly cooled in a water bath at 10 to 40 ° C. to obtain an aluminum plate having a film coated on both sides. At the time of coating, the initial adhesion was good, and there were no problems such as fluctuations in tension and winding around the nip roll, and the coating film of this example had good coating suitability. Thereafter, the film-coated aluminum plate for coating was heated and remelted at 275 ° C. and then quenched in water to prepare a remelt aluminum plate.
[Production of film-coated metal cans]
The produced remelt aluminum plate was drawn and ironed so that the thickness reduction rate was 30% to form a film-coated metal can. At the time of molding, there was no peeling or tearing of the coating film, and the releasability from the mold was good, which was extremely good. After that, the film-coated metal can for coating was heated and re-melted as described above, and then rapidly cooled in water. . Furthermore, after printing the outer surface, a varnish was applied, and after heat-curing, it was quenched with cold air.
The metal can thus formed was filled with a beverage, and a lid with a tab was wound and joined, followed by hot water treatment at 80 ° C. for 30 minutes to produce a two-piece beverage can. The resulting beverage can had good can-making properties, and neither oligomer elution into the beverage nor oligomer precipitation from the coating film. In addition, the adhesiveness did not deteriorate with the passage of time, and the film was not broken in the impact resistance test. The evaluation results are shown in Table 1.

[Example 2]
The same polyester composition (polyester composition A1) as in Example 1 was used for the polyester A layer.
For the polyester B layer, 20% by weight of dimer acid copolymerized PET in which the dicarboxylic acid component is 90 mol% of terephthalic acid units, 10 mol% of dimer acid units having 36 carbon atoms, and the diol component is 100 mol% of ethylene glycol units. Polyester composition B2 in which 48% by weight of PET and 32% by weight of PBT were mixed was used. The composition ratio of the copolyester was confirmed using the above-mentioned 1H-NMR (manufactured by varian, UNITY 50).
The ratio of the aliphatic dicarboxylic acid having 10 or more carbon atoms (= dimer acid) in the raw material component in the polyester composition B2 is 10 × 20 ÷ 100 because b and c described above are b = 10 and c = 20, respectively. = 2, that is, 2 mol% of the total acid component.
Polyester composition A1 and polyester composition B2 were each dried with a paddle dryer, fed to a funnel-shaped hopper directly above a single screw extruder, and melted in the extruder. Each melt was extruded from each extruder to a ratio of polyester composition A / polyester composition B = 50/50% by weight, merged in a die, extruded and quenched, and unstretched two-layer base A film was obtained. A portion of this unstretched bilayer base film was cut out and the thermal properties were measured. The results are shown in Table 1.
The obtained unstretched two-layer base film was stretched 3.3 times in the machine direction at a preheating temperature of 65 ° C. and a stretching temperature of 100 ° C., and further in the tenter at a preheating temperature of 65 ° C. and a stretching temperature of 90 ° C. After stretching 4.0 times in the direction, heat treatment is performed at 160 ° C. for 8 seconds, and 4% relaxation treatment is performed at 160 ° C., and the thickness is 20 μm (the thickness of the polyester A layer is 10 μm, the thickness of the polyester B layer is 10 μm). A biaxially stretched bilayer base film was obtained.
The same coating liquid as used in Example 1 was coated on the polyester B layer side by the gravure coating method on the two-layer base film, and dried at 160 ° C. for 8 seconds, and then the drawing and squeezing of Example 2 was performed. A film for covering an iron can was obtained. The thickness of the adhesive resin layer of the obtained drawn / ironing can coating film was measured by the weight method. The average thickness of the adhesive resin layer was 30 nm as set. Further, the variation in the thickness of the adhesive resin layer of 100 samples was 9 nm at maximum. The results are shown in Table 1.
The subsequent metal plate coating process, can making process, and evaluation are in accordance with Example 1.
As in Example 1, the metal can thus prepared had extremely good moldability, and neither the oligomer eluted into the beverage nor the oligomer deposited from the coating film. Furthermore, the adhesiveness did not deteriorate with the passage of time, and the coating film did not break in the impact resistance test. The evaluation results are shown in Table 1.

[Comparative Example 1]
Other compositions, film forming steps, can manufacturing steps, and evaluations were performed in the same manner as in Example 1 except that the concentration of the same coating solution as in Example 1 was adjusted so that the thickness of the adhesive resin layer was 70 nm. .
The thermal characteristics of the base film of the drawing / ironing can coating film of Comparative Example 1 are shown in Table 1 (same as Example 1). The average thickness of the adhesive resin layer was 70 nm as set. Further, the variation in the thickness of the adhesive resin layer of 100 samples was 8 nm at the maximum. The film-coated metal plate and film-coated metal can prepared using this coating film have poor adhesion to the metal plate due to the thick adhesive resin layer, and film peeling occurs in the remelt process. Example 1 Compared to, the processability was inferior and the yield was low. In Comparative Example 1, a normal film-covered metal can could not be prepared, so an impact resistance test was not performed. The evaluation results are shown in Table 1.

[Comparative Example 2]
Except for adjusting the coating solution concentration and coating speed during coating so that the thickness of the adhesive resin layer is 5 nm to 50 nm in the longitudinal direction of the film roll, examples of the composition, film formation process, can manufacturing process, and evaluation Same as 2.
The thermal characteristics of the base film of the drawing / ironing can coating film of Comparative Example 2 are shown in Table 1 (same as Example 2). The average thickness of the adhesive resin layer was 30 nm. Moreover, the maximum variation in the thickness of the adhesive resin layer of 100 samples was 26 nm. The film-coated metal can prepared using this coating film was inferior in moldability in the thick / thin part of the adhesive resin layer as in Comparative Example 1.
Although the thickness of the adhesive resin layer was within the preferred range, the film was not peeled off, etc. and could be created as a film-covered metal can, the film did not break in the impact resistance test and showed good characteristics, The film roll as a whole was not preferable in terms of yield. The evaluation results are shown in Table 1.

注）※印部は、フィルムロール全体での評価とした。

Note) * marked part is evaluated as the whole film roll.

  As described above, the drawing / ironing can coating film of the present invention has a good moldability and excellent adhesion for drawing / ironing can coating, particularly when used as a two-piece can coating film. It is a film. Further, the base film has a two-layer configuration of polyester A layer / polyester B layer, and 2 to 15 mol% of the total acid component among the polyester raw material components of the polyester B layer is an aliphatic dicarboxylic acid having 10 or more carbon atoms, By setting the polyester B layer to be on the side of the surface to be bonded to the metal plate, it is possible to obtain a film for covering a drawn and ironing can having better moldability and excellent adhesion. Furthermore, the film-coated metal plate for drawing and ironing can coated with the film for covering the drawing and ironing can of the present invention is excellent in molding process stability, and is a film obtained by molding the film-coated metal plate for drawing and ironing can of the present invention. The coated drawing / ironing can has excellent appearance characteristics and impact resistance.

Claims (4)

A coating film in which an adhesive resin layer made of a thermoplastic resin is provided on a base film made of a thermoplastic resin, wherein the base film and the adhesive resin layer are made of a thermoplastic polyester resin, The polyester which has two layers of A layer / B layer and constitutes the A layer of the base film is a polyester mainly composed of mixed polyester in which polyethylene terephthalate and polybutylene terephthalate are blended, and B of the base film Among the polyester raw material components of the polyester constituting the layer, 2 to 15 mol% of the total acid components are aliphatic dicarboxylic acids having 10 or more carbon atoms, and the adhesive resin layer is thermoplastic on the surface of the B layer of the base film. and characterized by being coated with a water-dispersible polymer compound consisting of polyester resin, further When 100 points are cut out as a sample at 100 m intervals in the longitudinal direction of the film roll while pulling out the covering film from a film roll formed by winding up the covering film for 10,000 m or more, adhesion of the cut out 100 points sample A film for covering drawn and ironed cans, wherein the thickness of the conductive resin layer falls within the range of 30 nm ± 20 nm. A film roll for squeezing and ironing can coating, wherein the film for squeezing and ironing can coating according to claim 1 is wound up in a roll shape at least 10,000 m or more. A film-covered metal plate for a squeezing and ironing can according to claim 1 , wherein the film for covering the squeezing and ironing can is coated on a metal plate so that the adhesive resin layer side is in contact with the metal plate. A film-coated drawn and ironed can obtained by molding and processing the film-coated metal plate according to claim 3 .