JP5498035B2 - Printed polyester film for coating can body material, method for producing the same, and can body using the same - Google Patents

Description

  The present invention relates to a printed polyester film that is heat-bonded to the outer surface of a metal plate for can body material via a thermosetting resin adhesive layer to form a surface protective coating layer, a method for producing the same, and a can body using the same About.

  As a can used for containers such as beverages, a cylindrical can body part is obtained by rounding a flat can body blank obtained by cutting a metal plate for can body material into a strip shape, and welding both end edges thereof. A so-called three-piece can with a separately manufactured can lid attached to the open end of the can body, forming a bottomed cylindrical can body by drawing or ironing a metal plate for can body material A so-called two-piece can is known.

  In the can body, a resin coating is applied to the inner surface of the can in order to prevent the flavor of the content from changing due to the metal component corroded or eluted due to the contact between the base metal and the content, Alternatively, a resin film is laminated and protectively coated. On the other hand, an image such as a predetermined display and design is formed on the outer surface side of the can by a printing coating method or a printing film laminating method.

  The printing coating method has a problem of influence on the working environment due to the heat of the heating oven and the organic solvent that volatilizes, and in recent years, as a method for solving the problem, there is a method of laminating and coating a preprinted printing film. It has been put into practical use (see Patent Document 1).

  According to the printing film laminating method, a resin composition comprising a thermosetting resin adhesive layer on one surface of a base polyester film and a pigment between the polyester film and the thermosetting resin adhesive layer A polyester film provided with a printed layer made of a product is thermally bonded to a metal plate for a can body material through the thermosetting resin adhesive layer, and images such as predetermined display and design on the outer surface side of the can body Can be formed. This method can provide cosmetics with images such as a predetermined display and design on the outer surface side of the can body without using print coating, and a can outer surface protection coated printing can body can be obtained without performing print coating and baking. Work environment is improved.

  However, when the printed polyester film is thermally bonded to the metal plate for can body material, the color tone of the printed layer is governed by the color tone of the can body material base, and a special color tone is obtained in the image of the predetermined display and design. There is an inconvenience.

  As a solution, as a printed polyester film that is heat-bonded to a metal plate for a can body material via a thermosetting resin adhesive to form a protective coating layer, a pigment excluding a pearl pigment on one surface of a base polyester film A first printed layer made of a resin composition containing a resin composition, a second printed layer made of a resin composition in which metal powder is dispersed on the first printed layer, and the second printed layer on the second printed layer. In addition, by using a metallic color printing film provided with a thermosetting resin adhesive layer, it is possible to suppress the influence of the base, and to achieve a metallic feeling and pigment color tone, thereby eliminating the above-mentioned problems and making cosmetics (See Patent Document 2).

  In recent years, as product differentiation through printing has progressed and beverage can bodies using printed films have increased, a can body with a more metallic feel has been demanded. For covering such can body materials for metallic tone bodies There is a need for printed films. In addition to the metallic tone, the printed film is required to have high quality, productivity, etc., such as print film manufacturability, adhesion to a can, and retort suitability of the obtained can. Yes.

  In the conventional metallic print film, a printed layer containing a pigment and a printed layer containing a metal powder are formed in this order on one surface of a base polyester film, and then an adhesive layer is formed thereon. As a method to do this, it is conceivable to use a metal powder having a larger particle size as the metal powder used in the printed layer containing the metal powder and to increase the amount used. However, in the normal printing, for example, general-purpose gravure printing, the depth of the plate cannot be increased due to restrictions such as printing speed and drying speed, and the printing ink thickness cannot be increased once. For this reason, it is difficult to use metal powder having a relatively large particle size in the printing ink, and forcibly using a large particle size causes clogging of the plate. Also, the amount of metal powder used in the printing ink is limited, and it is not possible to use a desired amount of metal powder having a desired large particle size. However, there is a problem that the metallic feeling cannot be improved as long as a metal powder having a small particle diameter is used.

  Furthermore, since the printing film takes a work process of being wound and stored once after the formation of the adhesive layer, the adhesive layer needs to be tack-free by drying for a short time, in order to increase productivity. The adhesive is required to have a good coating workability, enable high-speed coating, dry in a shorter time, and have a tack-free surface after drying. Further, when the printing film is bonded to the surface of the can body material, it is necessary to obtain a strong adhesive effect, and the obtained can body is also required to have no whitening after retorting, and the printing film adhesive composition As a thing, the thing excellent also about those characteristics is calculated | required.

Japanese Patent Laid-Open No. 5-96627 Japanese Patent No. 3485333

  The present invention eliminates such inconveniences, and improves the various properties required for an adhesive when forming a protective coating layer by coating the outer surface side of a metal plate for can body material with a printed polyester film, It is an object of the present invention to provide a printed polyester film for covering a can material, which can give a color tone with a further enhanced metallic feel to a predetermined display and design image.

  Another object of the present invention is to provide a method for producing the printed polyester film for covering a can material and a can using the printed polyester film for covering a can material.

In order to achieve the above-mentioned object, the printing polyester film for covering a can body material of the present invention is a print in which a protective covering layer is formed by being heat-bonded to a metal plate for a can body material via a thermosetting resin adhesive layer. A thermosetting resin in which a printed layer made of a resin composition containing a pigment is provided on one surface of a base polyester film, and a metal powder is dispersed on the printed layer. The thermosetting resin-based adhesive layer is prepared by adding a non-blocked isocyanate compound to a mixture of a polyester resin and a blocked isocyanate compound with respect to the total amount of the adhesive layer. a resin composition comprising in the range of .1～5 wt%, with a thickness in the range of 3 to 7 [mu] m, the metal powder, the surface direction of magnitude mean 1 5 to 50 [mu] m range, the thickness There wherein the flaky aluminum powder in the range of 0.1-2 .mu.m, is a layer containing a range of 30 to 70% by weight based on the total amount of the adhesive layer.

  As the pigment used in the printing layer, organic pigments and inorganic pigments that have been generally used can be used. In addition, as the resin composition for forming the printed layer, conventionally used resin compositions can be used, but a resin composition comprising an epoxy butyral resin and a polyisocyanate resin, or a polyester polyurethane resin A resin composition comprising a polyisocyanate resin is preferred. The can body of the present invention is usually subjected to heat sterilization treatment (retort sterilization treatment) after filling the contents. However, when the retort treatment is performed, the printing layer is whitened if the printing layer is selected incorrectly. An image such as a predetermined display and design formed by the layers may become unclear. However, since the epoxy butyral resin and the polyisocyanate resin or the resin composition comprising the polyester polyurethane resin and the polyisocyanate resin are formed, a protective coating layer is formed from the can body material covering polyester film. Even if the retort treatment is performed on a can formed from a metal plate for a can body material, the printed layer is not whitened and a clear image can be obtained.

Next, as the thermosetting resin adhesive layer of the present invention, a metal powder-containing resin composition in which metal powder is dispersed in a thermosetting resin is used. The resin composition, port Riesuteru resin and thermosetting resin composition comprising a blocked isocyanate compound as a main component, the non-blocked in the range of 0.1 to 5% by weight relative to the total amount of the adhesive layer isocyanate compound The resin composition which mix | blends and uses (unblocked isocyanate compound) just before use can be mention | raise | lifted.

  The printing film adhesive coating process is separate from the printing process using printing ink containing pigment, and the printing layer is constrained to the printing process by coating the adhesive layer in a separate process on the printed film. The coating can be performed at a suitable coating speed condition. In addition, the adhesive can be applied deeper than the printing ink and can be thickly coated. Therefore, a relatively large amount of metal powder with a relatively large particle size that could not be used with the printing ink can be used. It can be used in a dispersed manner.

Examples of the metal powder dispersed in the thermosetting resin-based adhesive composition include powders such as aluminum, zinc, brass, and stainless steel. In order to give a color tone having an excellent metallic feeling, it is suitable to use a metal powder having a large particle size, and in particular, the flake shape is 15 to 50 μm on average in the surface direction, preferably the flake thickness is 0 Use flaky aluminum powder with silver metallic luster of 1-2 μm. In the case of aluminum powder, it is suitable to use the powder dispersed in the range of 30 to 70% by weight . If the size of the flakes is small, the metallic feeling does not appear, and if it is too large, the coating workability is deteriorated. Further, if the amount used is small, a metallic feeling cannot be obtained, and if it is too large, the effect does not change so much and the coating workability is lowered, which is not preferable. Further, it is suitable that the film thickness after drying is 3 to 7 μm, and if it is thin, a metallic feeling cannot be obtained, and if it is too thick, the work adhesion after bonding the printed film is unfavorable.

  The printed polyester film provided with the adhesive layer in which the metal powder is dispersed is heat-bonded to the outer surface of the can body made of the metal plate for can body material, thereby making it possible to obtain unique peculiar to the can body by the conventional print film. A color tone having an excellent metallic feeling with a glittering feeling can be imparted. When the aluminum powder dispersed in the resin composition is less than 20% by weight, a metallic feeling may not be obtained in the images such as the predetermined display and design, and even if it exceeds 70% by weight, an effect of imparting a metallic feeling Is not obtained any more, and the adhesive strength is lowered.

  The adhesive layer of the printing film of the present invention is coated at a high speed with the metal powder dispersed, for example, at a speed of about 100 m / min, so that the metal powder is in a stable dispersed state and can be painted. An appropriate viscosity is required. And since it takes the process of winding up at high speed after painting and drying on the printed layer of the base polyester film, it is necessary to dry in a short time and to make the adhesive surface after drying tack-free. In addition, after being laminated to a flat or cylindrical metal body for cans via an adhesive layer, it must be firmly adhered to the outer surface of the can body, and no whitening will occur during retort processing after filling the contents. Is required.

  Dispersion stability and high-speed coating suitability of such relatively large particle size metal powder, tack-free suitability when winding and reusing a coating film, adhesion to metal materials, and retort of the resulting can body From the viewpoint of suitability, etc., in the present invention, the adhesive mainly comprises a thermosetting resin composition composed of a polyester resin and a blocked isocyanate compound, and a small amount of an unblocked isocyanate compound is blended immediately before coating. Agent compositions are particularly suitable. That is, when the viscosity of the adhesive solution before coating containing the metal powder is too low, the dispersion stability of the blended metal powder is lowered, and when it is too high, the coating workability is lowered. In the present invention, by adding a small amount of unblocked isocyanate compound just before use, the amount of solvent used, the resin content, the amount of metal powder remains the same, the polyester resin and the isocyanate compound are reacted to adjust the viscosity, Coating can be carried out by adjusting the viscosity within a suitable range suitable for both ensuring the dispersion stability of the metal powder and coating workability. Furthermore, the adhesive layer after drying, which has been stripped of the solvent, has a blocked isocyanate compound that remains substantially unreacted, and the polyester resin used is polymerized by reaction with the isocyanate compound and becomes tack-free. The film winding and storing workability is improved. By laminating this film on a metal plate for can body material and heating, the polymerized adhesive composition is released from the blocking agent of the blocked isocyanate compound, and the thermosetting reaction with the polyester further proceeds. Adhesive strength with the body substrate is further improved, and adhesive strength that can withstand retort treatment can be obtained. Moreover, the obtained printed film can give the outstanding metallic feeling by laminating on a can.

  The polyester resin used in the thermosetting resin-based adhesive composition containing the polyester resin and the blocked isocyanate compound includes a side chain or a terminal obtained by a condensation polymerization reaction of a polyvalent carboxylic acid compound and a polyhydric alcohol compound. A polyester resin having a hydroxyl group and having a molecular weight and a glass transition temperature (Tg) that are tack-free at room temperature after reaction with an isocyanate compound is suitable. The glass transition temperature (Tg) is 10 ° C or higher, preferably 20 ° C to 65 ° C. Examples of the blocked isocyanate compound used as the curing agent include a blocked isocyanate compound obtained by reacting an aliphatic, aromatic or alicyclic polyfunctional isocyanate compound with a known blocking agent.

  Examples of the polyfunctional isocyanate compound include aliphatic diisocyanates such as lysine diisocyanate and hexamethylene diisocyanate, alicyclic isocyanate compounds such as hydrogenated xylylene diisocyanate and isophorone diisocyanate, and aromatics such as tolylene diisocyanate and xylylene diisocyanate. Isocyanates can be raised. Examples of such a blocking agent for an isocyanate compound include known blocking agents such as phenols such as phenol and cresol, lactams, and the like.

  The adhesive composition of the present invention is preferably composed mainly of a polyester resin and contains a blocked isocyanate compound in the range of 1 to 10% by weight, preferably about 1 to 5% by weight, based on the total amount of the adhesive composition. Yes. If it is less than 1% by weight, the curing reaction at the time of thermal bonding of the laminate to the can is insufficient, and the adhesion to the can and the retort suitability are insufficient. This is not preferable. In addition, as an unblocked isocyanate compound used immediately before use, an aliphatic polyfunctional isocyanate compound as described above is 0.1 to 5% by weight based on the total amount of the adhesive composition, Preferably, it is suitable to use in the range of about 0.2 to 3% by weight. If it is less than 0.1% by weight, it is difficult to adjust the coating viscosity, the adhesive surface after coating and drying is not easily tack-free, the workability at the time of reuse after winding is deteriorated, and the film is adhered to a metal material. Later adhesiveness is also lowered, which is not preferable. On the other hand, if it exceeds 5% by weight, the resin solution after blending tends to thicken, and the coating workability deteriorates.

  As a method of using the adhesive composition, a resin solution containing a polyester resin and a blocked isocyanate compound is blended with an isocyanate compound that is not blocked immediately before use, while considering an increase in viscosity due to the reaction of the isocyanate compound. The lower and upper limits of viscosity are set to an appropriate viscosity range that is suitable for metal powder dispersion stability and does not interfere with the coating workability, and is coated on a printed film with a general-purpose coater, preferably a gravure coater. To do. As the viscosity of the resin solution at the time of coating, a range of 20 seconds to 40 seconds is suitable for Ford Cup # 4. If the viscosity is too low, the metal powder tends to settle, resulting in poor dispersion stability and uneven coating.If the viscosity is too high, the fluidity of the resin is reduced, resulting in poor coating workability and uneven coating. This is not preferable. After the adhesive is applied, heat treatment is performed at a high temperature for a short time so that the substantial curing reaction between the blocked isocyanate compound and the polyester resin does not proceed, drying the solvent and promoting the reaction between the added isocyanate compound and the polyester resin. The adhesive layer can be made tack-free by making the adhesive layer more polymerized. In this way, the film can be wound and stored at high speed, and the workability and adhesiveness when the film is bonded to a metal plate for can body material are further improved.

  A small amount of a block dissociation catalyst can be appropriately used for the thermosetting adhesive. Moreover, an epoxy resin, a polyurethane resin, etc. can also be mix | blended suitably as a modifier.

  Moreover, as said epoxy resin / acid anhydride type thermosetting resin-based adhesive layer, an epoxy resin having a number average molecular weight of 5000 to 20000 and an acid anhydride type curing agent in a weight ratio of 70/30 to 99/1. The polyester resin / aminoplast resin thermosetting resin adhesive layer is made of a resin containing a polyester resin and an aminoplast resin in a weight ratio of 70/30 to 90/10. By using this, sufficient adhesive strength can be obtained between the polyester film for covering a can body material and the metal plate for a can body material by heating at a high temperature for a short time.

  The epoxy resin is not preferred because the adhesive strength is insufficient when the number average molecular weight is less than 5,000, and the viscosity becomes high when the number average molecular weight exceeds 20,000, resulting in poor coating workability. Moreover, when the number average molecular weight is less than 5,000, when the adhesive layer is formed by applying and drying the polyester film in advance, the tackiness of the adhesive layer is increased and the tack-free property is lowered. Further, when the weight ratio of the epoxy resin to the acid anhydride curing agent is less than 99/1, it takes a long time to cure the epoxy resin even when heated at a high temperature, and the ratio exceeds 70/30. The effect of promoting the curing of the epoxy resin is not further improved.

  Examples of the acid anhydride-based curing agent include pyromellitic anhydride, benzophenonetetracarboxylic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, methylcyclohexanedicarboxylic anhydride, trimellitic anhydride, and derivatives thereof. However, a trimellitic anhydride-based curing agent composed of trimellitic anhydride and its derivatives is suitable because it is excellent in curability, blocking resistance of the film after coating, tack-free property, and the like. Examples of the derivative of trimellitic anhydride include glycerol tristrimellitic anhydride, dimer of trimellitic anhydride, ethylene glycol bistrimellitic anhydride, and the like.

  The epoxy resin forming the adhesive layer is preferably a bisphenol type epoxy resin obtained by a reaction of bisphenol and epichlorohydrin, and further contains other curing agent such as phenol resin in addition to the acid anhydride curing agent. You may go out.

  In order to obtain sufficient adhesive strength between the can body material covering polyester film and the can body material metal plate, the resin composition forming the adhesive layer can be heated at a high temperature for a short time. It is preferable to use selectively according to the kind of resin which forms a printing layer. When the adhesive layer is composed of an epoxy resin and an acid anhydride-based curing agent, there is no volatilization of the blocking agent at the time of thermosetting, and therefore it is also suitable as an adhesive for film adhesion on the inner surface side of the can body.

  Prior to use, the polyester film may be heat-treated at 160 ° C. for about 6 seconds in order to ensure the dimensional stability, but on the opposite side of the surface on which the adhesive layer is provided. A cured overcoat layer made of a thermosetting resin is preferably provided. By providing the cured overcoat layer, the residual stress of the polyester film is relaxed, the expansion and contraction of the film is restricted, the dimensional stability is ensured, and the scratch resistance is improved. Further, by providing the cured overcoat layer, the can body obtained from the metal for can body material in which the protective coating layer is formed by the polyester film for covering the can body material is filled with the contents, and the retort sterilization treatment etc. When the heat treatment is performed, the low polymerization degree component (oligomer) in the polyester film is prevented from being deposited on the surface. In addition, the slipperiness is improved. Such an overcoat layer may be applied at the stage of producing a printing film in advance, or after laminating a printing film not provided with an overcoat layer on a cylindrical can body, an overcoat layer may be formed on the surface. .

  The thermosetting resin that forms the cured overcoat layer is preferably a resin that forms a cured film at a high temperature in a short time. For example, the thermosetting resin is composed of an epoxy resin and an aminoplast resin and is used as an organic acid or phosphorous as a short-time curing catalyst. A material to which an inorganic acid such as acid or polyphosphoric acid is added is suitable. It is preferable that silicon or wax is added to the thermosetting resin in order to improve scratch resistance and slipperiness.

  As the base polyester film of the printed polyester film for covering a can material, those having excellent strength and transparency obtained by polycondensation of a dicarboxylic acid component and a diol component are suitable. Naphthalene dicarboxylic acid, terephthalic acid Polyesters obtained by polycondensation of aromatic dicarboxylic acids such as isophthalic acid and diols such as ethylene glycol, propylene glycol and butylene glycol are preferred.

  The polyester film is preferably subjected to surface oxidation treatment such as corona discharge in advance on the surface on which the adhesive layer is formed in order to improve the adhesive strength of the thermosetting resin adhesive described later.

  The polyester film preferably has a thickness in the range of 5 to 50 μm. When the thickness of the polyester film is 5 μm or less, the film is easily damaged in the process of adhering the protective coating layer of the film to the can body material or in the subsequent processing process, and pinholes are generated. Therefore, the effect of preventing corrosion of the can body and elution of the metal may not be sufficiently obtained. Further, when the thickness is 50 μm or more, the residual stress becomes large, and when the can body is subjected to a drawing process such as a neck-in process when being processed into a welded can body, the polyester film has an adhesiveness to the metal plate for the can body material. There is a tendency to decrease.

  Furthermore, since the polyester film is required to have strength for providing the printing layer and dimensional stability against heat treatment when bonded to the metal plate for can body material, heat-resistant polyester film such as polyethylene naphthalate, A uniaxially or biaxially stretched polyethylene terephthalate film or the like is preferable. In particular, the material has a heat shrinkage rate of 1.2% or less when held at 150 ° C. for 30 minutes, and a heat shrinkage rate in the width direction. A 0% biaxially stretched polyester film is preferred.

  Examples of the metal plate for the can body material include a tin-plated steel plate, a TFS plate, an aluminum plate, a surface-treated metal plate subjected to various surface treatments on the surface thereof, a laminate of a plastic film, or a resin coating. Can be used as appropriate.

  Moreover, the said metal plate for can body materials which laminates the printing polyester film of this invention may be flat form, or what was formed in the cylindrical shape. In the case of using a flat metal plate, after laminating a printing film on the metal plate, it can be rolled into a cylindrical shape by a known method such as a welding can forming method, and an outer surface printed film laminated can body can be obtained by attaching a can lid. I can do it. Further, a so-called two-piece can having a bottomed cylindrical shape is formed by drawing or ironing using a metal plate having a plastic film laminated on the surface, and the printing film is laminated on the can body by a known method. Thus, an outer surface printed film laminate can body can be easily formed.

  For example, in the case of an outer surface printed film laminate welded can, the present invention is applied to one surface which is the outer surface side of the can body material outer surface side of the flat plate-like metal plate, except for both side edge portions. The canned polyester material coating polyester film is heat-bonded through the adhesive layer, and a protective coating layer is provided on the other inner surface of the can. A can body can be formed by overlapping and welding and then a can lid can be double-wrapped closed at one open end to obtain a three-piece welded can.

  In the case of a two-piece can with an outer surface printed film laminate, a flat plate with a protective film laminated on the inner and outer surfaces is drawn or ironed into a bottomed cylindrical shape, and then formed on the outer surface of the can body portion of the can body. On the other hand, a two-piece can body can be obtained by forming a protective coating layer by heating and bonding the printed polyester film for coating a can body material of the present invention via the adhesive layer, and forming a can body portion.

  In the can body of the present invention, it is desirable that a protective coating layer is formed on the inner surface side of the can body portion by coating or film lamination according to the contents. Examples of the film for forming the protective coating layer on the inner surface side of the can body portion include a polyester film in which a thermosetting resin adhesive layer is provided on one surface. In addition, since such a polyester film may be plain and does not need to provide a printing layer, strength, dimensional stability, etc. like the polyester film which forms a protective coating layer on the said outer surface side are not strictly requested | required. Therefore, it may be an unstretched polyester film or a uniaxial or biaxially stretched polyester film, but it is suitable for the process of coating a metal plate for can body material, when it becomes a can body From the viewpoint of can quality, polyethylene terephthalate film is suitable.

  When the printed polyester film for covering a can body material of the present invention is heated and bonded to a metal plate for a can body material by the adhesive layer provided on one surface thereof, the protective film is formed. An image having a predetermined display and design is formed on the outer surface side of the can body forming metal plate by the printed layer provided on the outer surface of the can body. At this time, since a thermosetting adhesive layer made of a resin composition in which metal powder is dispersed is interposed between the printing layer and the metal base of the metal plate for can body material, printing of the printing layer is performed on the can body. The printed layer gives a color tone having an excellent metallic feeling to the image of the predetermined display and design without being controlled by the color tone of the metal base. Since the adhesive layer can be coated with a thick film in a single coating process as compared with the gravure ink layer, a relatively large amount of metal powder having a large particle size can be used. As a result, a unique and glittering metallic print finish can be obtained, and a can body excellent in cosmetics can be obtained. Also, since thick film coating is possible compared to the ink layer, the number of print coating processes can be reduced compared to the overcoating thick film finishing in the conventional printing process, and the printing process can be simplified. Since the printing layer is provided between the polyester film and the metal can body member as described above, the printing layer is shielded by the polyester film and protected from damage.

  The adhesive layer of the present invention is coated at a high speed with the metal powder dispersed, for example, at a speed of about 100 m / min, so that the metal powder is in a dispersed state and has an appropriate viscosity that can be applied. Therefore, the film is coated on the printed layer of the base polyester film, and after heating and drying, the film is wound at a high speed. Therefore, the film needs to be dried in a short time and tack-free. Furthermore, after being laminated on a flat or cylindrical metal material, it is required to be thermally cured and firmly bonded to the outer surface. In the present invention, in terms of dispersion stability and high-speed coating suitability of the metal powder, tack-free suitability after lamination, adhesion to a metal material, retort suitability of the resulting can, etc., in the present invention, a polyester resin and a blocked isocyanate compound A non-blocked isocyanate compound and a reactive group in the polyester resin by using an adhesive composition composed mainly of a thermosetting resin composition comprising a small amount of an unblocked isocyanate compound immediately before coating. Can be applied by adjusting to an appropriate viscosity suitable for coating while ensuring the dispersion stability of the metal powder. Furthermore, the adhesive layer of the film after drying is such that the blocked isocyanate compound remains substantially unreacted and the polyester resin used is polymerized to become tack-free, so that the workability of winding and storing the film is improved. improves. By laminating this film on a metal plate for can body materials and heating, the polymerized adhesive composition is released from the blocking agent of the blocked isocyanate compound, and the thermosetting reaction with the polyester resin further proceeds, and the can The adhesive strength with the surface of the body material is further improved, and the adhesive strength that can withstand the retort treatment can be obtained.

  The printed polyester film for coating a can material according to the present invention is provided with a metal for can material by providing a cured overcoat layer made of a thermosetting resin on the opposite side of the surface on which the adhesive layer is provided. When heat-bonded to the plate via the adhesive layer, residual stress of the polyester film is relaxed and expansion and contraction is restricted, so that dimensional stability against heat treatment is ensured. In addition, when forming a welded can body from the metal plate for can body material formed by heat-bonding the polyester film and forming the protective coating layer with the cured overcoat layer, the heat treatment such as the retort sterilization treatment is performed. Further, precipitation of the oligomer in the polyester film on the can surface and scratching of the film surface are prevented, and the slipperiness of the can surface is improved.

  Moreover, according to the can body of the present invention, the can outer surface side is coated with the can body material covering polyester film, and the can body portion provided with a color tone having an excellent metallic feeling in the image of the predetermined display and design. As a result, excellent cosmetic properties can be obtained on the outer surface side of the can body.

  As is clear from the above, according to the polyester film for covering a can body material of the present invention, when the protective coating layer is formed by being heat-bonded to the can body metal part, the printed layer is composed of the metal powder. The metallic layer made of the thermosetting adhesive layer made of the dispersed resin composition can give a color tone having a metallic feeling excellent in predetermined display and design without being controlled by the color tone of the metal base.

The adhesive layer contains aluminum powder having an average particle size of 15 to 50 μm in a range of 30 to 70% by weight and forms a layer having a thickness of 3 to 7 μm. Can be granted.

  The adhesive layer contains a non-blocked isocyanate compound in a mixture of the polyester resin and the blocked isocyanate compound in a range of 0.1 to 5% by weight with respect to the total amount of the adhesive layer. Viscosity is adjusted by reacting the polyester resin and the isocyanate compound while maintaining the solvent usage, resin content, and metal powder content, making it suitable for both ensuring the dispersion stability of the metal powder and coating workability. It can be adjusted to paint. Furthermore, in the adhesive layer after drying with the solvent stripped, the blocked isocyanate compound remains substantially unreacted, and the polyester resin used becomes polymerized and becomes tack-free. Winding and storage workability is improved. When the adhesive layer is laminated on a metal plate for can body material and heated, the blocking agent of the blocked isocyanate compound is released and the thermosetting reaction with the polymerized polyester further proceeds. Strength is further improved, and adhesive strength that can withstand retort processing can be obtained.

  Further, the polyester film for covering a can material of the present invention has a cured overcoat layer made of a thermosetting resin on the opposite side of the surface on which the adhesive layer is provided. It has excellent dimensional stability with respect to heat treatment, and can prevent precipitation of oligomers due to heat treatment such as retort sterilization when a can body is formed. Further, scratch resistance and can material, can body slip Can be improved.

  According to the can body of the present invention, the outer surface side of the can is covered with the can body material covering polyester film, and a can body portion having a color tone having an excellent metallic feeling is formed in the image of the predetermined display and design. Therefore, the cosmetics excellent in the outer surface side of the can body can be obtained from the image.

(A) is explanatory sectional drawing which shows one structural example of the printing polyester film for can body material coating concerning this invention, (b) is other printing polyester film for can body material coating concerning this invention It is explanatory sectional drawing which shows a structural example. It is explanatory sectional drawing which shows the structure of the metal plate for can body materials in which the printing polyester film for can body material coating | cover shown to Fig.1 (a) was formed. It is explanatory partial sectional drawing which shows the can body part of the welding can body formed from the metal plate of FIG. It is explanatory partial sectional drawing which shows the bottomed cylindrical 2P metal can obtained by drawing or ironing the film lamination metal plate which laminated the polyester film on both surfaces of the TFS metal plate. FIG. 5 is an explanatory partial cross-sectional view of a two-piece can in which a printed polyester film for covering a can body material is laminated on the outer surface side of the cylindrical can body shown in FIG. 4 and neck-in processing and flange processing are applied to an opening.

  Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

  First, the printed polyester film for covering a can material of the present embodiment will be described.

  As a printing film 1a bonded to the outer surface of the can body of a metal can body, as shown in FIG. 1 (a), a biaxially stretched polyethylene terephthalate (hereinafter, polyethylene terephthalate is abbreviated as PET) film 2 having a thickness of 12 μm. Is provided with a printing layer 3 that has been subjected to gravure printing with a printing ink containing a pigment, and an adhesive layer 4 made of a thermosetting resin-based adhesive containing aluminum powder. A transparent cured overcoat layer 5 formed of a curable resin is provided. Further, as shown in FIG. 1B, a printing film 1b without a cured overcoat layer is formed as a printing film for providing a cured overcoat layer as desired after the printing film is adhered.

  The printing layer 3 is made of a printing ink made of an epoxy butyral resin and a polyisocyanate resin and containing a pigment. The printing layer 3 is printed in multiple colors by laminating the printing ink containing pigments of required colors for each color by gravure printing in order to form a predetermined display and design image on the outer surface side of the can. . The thickness of the printing layer 3 is set to about 1 μm after drying. An image having a predetermined display and design is formed by the printing layer 3.

  The adhesive layer 4 is mainly composed of a thermosetting resin composition in which a blocked isophorone diisocyanate compound is blended with a polyester resin in an amount of 2% by weight based on the total amount of the adhesive composition as a preferred adhesive composition. A non-isocyanate compound is used in an amount of 1% by weight based on the total amount of the adhesive composition immediately before construction. An adhesive composition in which 50 wt% of aluminum powder having an average flake size of 28 μm is dispersed in a resin solution in which the resin composition is dissolved in an organic solvent with respect to the total amount of the adhesive composition is adjusted to an appropriate viscosity. As a drying condition, drying was performed at 160 ° C. for several seconds at a temperature at which the removal of the solvent and the reaction of the isocyanate compound proceeded but the reaction of the blocked isocyanate compound did not proceed substantially. The film thickness of the adhesive after drying was 5 μm. The adhesive layer applied on the printing layer 3 was dry and tack-free, and the continuously applied printing film was wound up at room temperature but was not sticky and had good workability. .

  As shown in FIG. 1A, the cured overcoat layer 5 is preliminarily applied to one surface of a polyester film, and a printed layer and an adhesive layer are formed on the other surface to form a printed film. As shown in 1 (b), either a method may be used in which a printed film without a cured overcoat layer is attached to a metal plate and then provided on the film surface. The cured overcoat layer 5 used is composed of an epoxy resin and an aminoplast resin, and is formed of a thermosetting resin to which a phosphoric acid catalyst is added. Further, the cured overcoat layer 5 is made of a can body having a protective coating layer formed of the polyester film 1, and silicon or wax is added to improve the scratch resistance of the polyester film 1 and the slipperiness of the can body surface. It is preferable.

  Next, a can body using the printed polyester film 1 of the present embodiment will be described.

  As shown in FIG. 2, the can body A of the present embodiment is formed from a tin plate 11 for forming a can body. The tin plate 11 for can body formation is obtained by thermally bonding the printed film 1a shown in FIG. 1 (a) through the adhesive layer 4 to the portion excluding the side edge portions 11a, 11a on the side that becomes the outer surface of the can. A protective coating layer 12 is formed. In FIG. 2, the printing layer 3 and the overcoat layer 5 of the printing film 1a are omitted. In addition, the transparent PET film 13 has an epoxy resin / anhydride-based thermosetting resin adhesive as an adhesive on the portion excluding the side edge portions 11b and 11b on the side that becomes the inner surface of the tin plate 11. A polyester film previously applied is thermally bonded through a thermosetting resin adhesive layer 14 to form an inner surface protective coating layer 15.

  Since the outer surface side of the tin plate 11 is covered with the printing film 1 a, the tin plate 11 is given an excellent metallic feeling to the image of the predetermined display and design formed on the protective coating layer 12 by the adhesive layer. . Here, as a pre-process for adhering the printing film, the tin plate may be subjected to a surface treatment, or a polyester film or the like may be laminated.

  Next, the tin plate 11 on which the protective coating layer 12 and the inner surface protective coating layer 15 are formed is rolled as shown in FIG. 3, and the side ends 11a and 11b are overlapped and welded to form a can body 16 Is formed. The portion of the can body portion 16 where the protective coating layer 12 and the inner surface protective coating layer 15 are not formed is covered with a known coating correction coating 17. And after carrying out the neck-in process and the flange process of the both-ends edge part of the can trunk | drum 16, the can body A of this embodiment is obtained as a 3 piece welded can body by double-tightening the separately manufactured can lid. It is done. In the can body A, the can body portion 16 is formed from the tin plate 11 that is covered with the printed polyester film 1a that is printed on the outer surface side of the can and the protective coating layer 12 is formed. The cosmetics excellent in the outer surface side of the can body part 16 can be obtained by the image of the predetermined display and design formed on the can, and can be suitably used for food cans, beverage cans and the like.

  In a welded can body, a retort sterilization process is usually performed after filling the contents. However, in the weld can body, even if the retort sterilization process is performed, whitening does not occur in the printed layer. Therefore, a clear image can be obtained with the predetermined display and design. For example, a can obtained by applying a printing film using the preferred adhesive of the present invention to the outer surface of a can body was subjected to a retort treatment at 125 ° C. for 30 minutes. The printed finish with a metallic feel was retained.

  In this embodiment, the resin composition comprising an epoxy butyral resin and a polyisocyanate resin is used as the resin composition for forming the printing layer. However, the resin composition comprising a polyester polyurethane resin and a polyisocyanate resin. Also in this case, the printed layer is not whitened during the retort sterilization treatment, and a clear image can be obtained in the predetermined display and design.

  Moreover, in this embodiment, you may use the thermosetting resin type adhesive agent which contains an epoxy resin and an acid anhydride type hardening | curing agent for the adhesive bond layer 4 other than the said resin composition. Further, the adhesive layer 4 may be a thermosetting resin adhesive containing a polyester resin and an aminoplast resin in a weight ratio of 70/30 to 90/10.

  The adhesive layer 4 may contain other pigments such as organic and inorganic pigments in addition to the metal powder. By including other pigments in the adhesive layer 4, not only the metal base is surely shielded when adhered to the tin plate 11 for can barrel formation, but also an excellent metallic feeling that enhances the printed pattern is obtained. .

  The tin plate 11 on which the protective coating layer 12 is formed forms a welded can body. The tin plate 11 is used to form a canned lid, a bottom lid of an aerosol can or a dome-shaped portion. You can also.

  Next, as the can body B of this embodiment, a two-piece metal can body including a cylindrical can body portion obtained by laminating the printing film of the present invention on the outer surface of the can body portion can be exemplified. As shown in FIG. 4, the can body B has a bottomed cylindrical shape formed by drawing or ironing using a film laminated metal plate in which polyester films 19 and 20 are laminated on both sides of a TFS metal plate 18. 2 piece metal can body 21 is obtained. As shown in FIG. 5, the can body 21 of the present embodiment is similar to the printing film 1a of FIG. 1 (a) or the printing film 1b of FIG. 1 (b) on the outer surface side of the cylindrical can body. A printed film 23 having a structure is laminated and used as a two-piece can body 26 having a neck-in process 24 and a flange process 25 applied to the opening.

  DESCRIPTION OF SYMBOLS 1a, 1b ... Print polyester film for covering can body material, 2 ... Base polyester film, 3 ... Printing layer, 4 ... Thermosetting resin adhesive layer, 5 ... Curing overcoat layer, 11 ... For can body material Metal plate, 11a, 11b ... side edge, 12 ... printed polyester film for covering can material, 16 ... can body, 21 ... bottomed cylindrical can, 22 ... printed polyester film laminate 2 piece can, 23 ... printed polyester film for covering can material.

Claims (5)

A printed polyester film that is heat-bonded to a metal plate for a can body material via a thermosetting resin adhesive layer to form a protective coating layer,
The printed polyester film is provided with a printed layer made of a resin composition containing a pigment on one surface of a base polyester film, and a thermosetting resin adhesive layer in which metal powder is dispersed is provided on the printed layer. And
The thermosetting resin-based adhesive layer contains a non-blocked isocyanate compound in a mixture of a polyester resin and a blocked isocyanate compound in a range of 0.1 to 5% by weight with respect to the total amount of the adhesive layer. a resin composition, with a thickness in the range of 3 to 7 [mu] m, the metal powder, the surface direction of magnitude mean 1 5 to 50 [mu] m range, the thickness is in the range of 0.1~2μm flaky aluminum A printed polyester film for covering a can material, which is a layer containing powder in an amount of 30 to 70% by weight based on the total amount of the adhesive layer. Wherein the opposite side of the surface on which the adhesive layer is provided for printing polyester film, that claim 1 Symbol mounting, characterized in that cured overcoat layer made of thermosetting resin is provided a can material coating Printing polyester film. On the outer surface side of the can body part formed from the metal plate for can body material, a printed layer made of a resin composition containing a pigment is provided on one surface, and a metal powder is dispersed on the printed layer. Forming a protective coating layer by heat-bonding a polyester film for covering a can material provided with a mold resin adhesive layer through the adhesive layer;
Resin The thermosetting resin-based adhesive layer, comprising a mixture of polyester resin and blocked isocyanate compound, a non-blocked isocyanate compounds, in the range of 0.1 to 5% by weight relative to the total amount of the adhesive layer made from the composition, with a thickness in the range of 3 to 7 [mu] m, the metal powder, the surface direction of magnitude mean 1 5 to 50 [mu] m range, the thickness is in the range of 0.1~2μm flaky aluminum powder Is a layer containing 30 to 70% by weight with respect to the total amount of the adhesive layer. 4. The can body according to claim 3 , wherein the printed polyester film-coated can body for covering the can body material is a welded can body or a bottomed cylindrical two-piece can body. For coating a can body material in which a printed layer made of a resin composition containing a pigment is formed on one surface of a base polyester film, and a thermosetting resin adhesive layer containing a metal powder is provided on the printed layer A method for producing a printed polyester film,
Thermosetting resin-based adhesive layer comprises a thickness in the range of 3 to 7 [mu] m, a mixture of polyester resin and blocked isocyanate compound, as a metal powder, the surface direction magnitude mean 1 5 to 50 [mu] m of A first resin solution is prepared by adding flaky aluminum powder in the range of 0.1 to 2 μm in thickness and in the range of 30 to 70% by weight with respect to the total amount of the adhesive layer. The second resin solution is prepared by adding an unblocked isocyanate compound in the range of 0.1 to 5% by weight to the first resin solution, and the second resin solution is applied onto the printed layer. A method for producing a printed polyester film for covering a can material, which is provided by heating and drying under a condition in which a thermosetting reaction of a blocked isocyanate compound does not proceed substantially.