JPH081863A - Polymer-coated metal laminate - Google Patents

Abstract

PURPOSE:To obtain a polymer-coated metal laminate adapted for a metal can in which impact resistance and taste characteristics are excellently compatible by coating a polyester layer having a specific melting point obtained by mixing ethylene glycol, butanediol residue, telephthalic acid residue and isophthalic acid residue at specific molar ratio by extrusion laminating. CONSTITUTION:A layer formed of polyester having a melting point of 120-265 deg.C obtained by mixing ethylene glycol residue and butanediol residue at a molar ratio of 20:80-95:5 and terephthalic acid residue and isophthalic acid residue at a molar ratio of 50:50-100:0 is covered by extrusion laminating. That is, in order to extrusion laminate the polyester having a specific melting point in which the ethylene glycol and butanediol are introduced on metal, in the case of molding to manufacture a can, excellent impact resistance is obtained even via many heat history such as heat treatment in the can forming step and retorting after the can forming.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to polymer coated metal laminates. More specifically, the present invention relates to a polymer-coated metal laminate having excellent moldability, impact resistance and taste characteristics, which is suitable for a metal can manufactured by a molding process.

[0002]

2. Description of the Related Art Conventionally, for the purpose of preventing corrosion, the inner and outer surfaces of metal cans are coated with various thermosetting resins such as epoxy or phenol dissolved or dispersed in a solvent to coat the metal surface. It has been widely practiced. However, such a coating method of a thermosetting resin has a problem that it takes a long time to dry the coating material, productivity is lowered, and environmental pollution is caused by a large amount of organic solvent.

As a method of solving these problems, a method of extruding and laminating a polymer on a steel plate, an aluminum plate or a metal plate which has been subjected to various surface treatments such as plating on the metal plate, which is a material for a metal can, and a film laminating method. There is. The former is advantageous in terms of cost, and when a metal can is manufactured by drawing or ironing a polymer laminated metal sheet, the polymer laminated metal sheet is required to have the following characteristics.

(1) It has excellent moldability and does not cause defects such as pinholes after molding.

(2) The polymer should not be peeled from the metal plate, or cracks or pinholes should not be generated by the impact on the metal can.

(3) The scent component of the contents of the can is adsorbed on the polymer, and the flavor of the contents is not impaired by the odor of the components eluted from the polymer (hereinafter referred to as taste characteristics).

Many proposals have been made to solve these demands, such as film laminating and extrusion laminating. Among these methods, the extrusion laminate is easier to reduce the cost as compared with the film laminate, but since it has no orientation, it is necessary to improve the properties of the coating polymer in order to impart impact resistance. For example, JP-A-51-17988 discloses a metal body obtained by extrusion-laminating a polyethylene terephthalate polymer having a crystallinity of 20% or less, and JP-A-51-148755 discloses a polymethylene terephthalate polymer in an amount of 200 to 350.
A metal body extruded and laminated on a metal body heated to ℃, Japanese Patent Publication No. 2-9935 discloses a metal body extruded and laminated with a multilayer polyester on a metal body heated to less than 200 ℃. However, these proposals are not ones that can comprehensively satisfy the various required characteristics described above, and cannot be said to be at a sufficiently satisfactory level particularly in terms of achieving both impact resistance and taste characteristics. It was

[0008]

The object of the present invention is to eliminate the above-mentioned problems of the prior art, and is excellent in moldability, impact resistance and taste characteristics, and particularly to achieve both impact resistance and taste characteristics at the same time. An object of the present invention is to provide a polymer-coated metal laminate suitable for a metal can manufactured by excellent molding.

[0009]

The above-mentioned object of the present invention is to provide ethylene glycol residues and butanediol residues in a molar ratio of 20:80 to 95: 5, and terephthalic acid residues and isophthalic acid residues in a molar ratio. In a ratio of 50:50 to 100: 0 and a layer (I) made of polyester A having a melting point of 120 to 265 ° C. is coated by extrusion laminating. be able to.

According to the present invention, a polyester having a specific melting point, into which an ethylene glycol component and a butanediol component have been introduced, is extrusion-laminated on a metal. It was found that good impact resistance can be obtained even when subjected to a lot of heat history such as retort treatment. The effect is extremely large as compared with the prior art in that impact resistance and taste characteristics can be compatible.

In the present invention, the ethylene glycol residue and the butanediol residue are in a molar ratio of 20:80 from the viewpoint of impact resistance.
˜95: 5, in terms of heat resistance and impact resistance, the molar ratio of terephthalic acid residue and isophthalic acid residue is 50:50 to 100: 0.
It is necessary to have the polyester A having a melting point of 120 to 265 ° C., which is blended in the proportion of. Here, if the molar ratio of butanediol residues exceeds 80, the taste characteristics on the inner surface of the can are greatly deteriorated and the workability is deteriorated due to the displacement between the laminated layers, which is not preferable, and if it is less than 5, the impact resistance is improved. It is not preferable because the effect does not appear. On the other hand, if the molar ratio of isophthalic acid exceeds 50, the impact resistance decreases, which is not preferable. Particularly in the case of a coated polymer on the inner surface of a can, in order to achieve both impact resistance and taste characteristics, the ethylene glycol residue and the butanediol residue are in a molar ratio of 50:50 to 95: 5, in terms of heat resistance and impact resistance. A polyester in which a terephthalic acid residue and an isophthalic acid residue are mixed in a molar ratio of 70:30 to 100: 0 is preferable. As long as the glycol residue and the dicarboxylic acid residue are in the above proportions, they may be copolymerized or blended, but from the viewpoint of productivity, a blended polymer is preferable. In that case, the melting point may appear in one point or two or more points in the differential scanning calorimeter (DSC).

Here, the polyester is a polymer composed of a dicarboxylic acid component and a glycol component, and dicarboxylic acid components other than the above, such as naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, 5- Aromatic dicarboxylic acids such as sodium sulfoisophthalic acid and phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, hydrogenated dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids A dicarboxylic acid component arbitrarily selected from alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and oxycarboxylic acids such as p-oxybenzoic acid may be copolymerized. On the other hand, as a glycol component, ethylene glycol, as a component other than butanediol, propanediol, pentanediol, hexanediol, an aliphatic glycol such as neopentyl glycol, a polyol such as polyethylene glycol, an alicyclic glycol such as cyclohexanedimethanol, Aromatic glycols such as bisphenol A and bisphenol S may be copolymerized. Two or more kinds of these dicarboxylic acid components and glycol components may be used in combination.

Further, a polyfunctional compound such as trimellitic acid, trimesic acid and trimethylolpropane may be copolymerized with the copolyester as long as the effects of the present invention are not impaired.

As the polyester A, an ethylene glycol / butanediol / terephthalic acid / isophthalic acid copolymer, an ethylene glycol / butanediol / polyethylene glycol / terephthalic acid / isophthalic acid copolymer, a polybutylene terephthalate or a copolymer thereof is used. A blend polymer with polyethylene terephthalate or a copolymer thereof is preferably used. Among them, a blend polymer of polybutylene terephthalate or a copolymer thereof and polyethylene terephthalate or a copolymer thereof is preferably used, but the polybutylene terephthalate or its copolymer preferably has a melting point of 120 to 225 ° C., and The melting point is preferably 130 to 225 ° C.

On the other hand, in consideration of the non-adsorptive property of the fragrance component of the can contents and the fact that the film layer does not shift due to the heat history received in the can manufacturing process, in addition to the above-mentioned film, the melting point difference is within 50 ° C. It is preferable to laminate a (II) layer made of polyester B containing ethylene terephthalate as a main constituent.

The polyester B is not particularly limited as long as the melting point difference with respect to the polyester A is within 50 ° C.
The melting point difference is preferably 40 ° C. or less, more preferably 30.
C. or less, more preferably 25.degree. C. or less is preferable because the difference in thermal expansion and contraction behavior between the (I) layer and the (II) layer is reduced during heat history in the can making process, and the workability is improved. In terms of composition, ethylene terephthalate is 60 mol% or more among the constituents in terms of taste characteristics, and preferably 70 mol% or more in terms of heat resistance. Preferred examples include polyethylene terephthalate, isophthalic acid copolymerized polyethylene terephthalate, polymers obtained by copolymerizing the polyester with diethylene glycol, and polyesters obtained by copolymerizing the polyester with a polyol such as polyethylene glycol. Further, butanediol and the like may be partially copolymerized, but in terms of improving taste characteristics, 20
It is preferably not more than mol%.

Further, from the viewpoint of heat resistance, the polyester B preferably has a melting point of 200 ° C. or higher.

In the present invention, the amount of carboxyl end groups of the polyester component is 40 in view of heat stability and taste characteristics of the polymer.
It is preferably not more than the equivalent weight / ton. More preferably, the amount of carboxyl terminal group is 35 equivalents / ton or less.
Specifically, solid phase polymerization, a method of reducing the amount of carboxyl terminal groups to a predetermined amount with a known end-capping agent such as carbodiimide, oxazoline and the like can be preferably performed.

On the other hand, increasing the amount of carboxyl terminal groups in the surface layer portion of the metal-bonded surface by surface treatment such as corona discharge treatment is preferable for improving the adhesiveness.

The polyester in the present invention preferably has an amount of diethylene glycol component of 0.01 to 5% by weight,
It is more preferably 0.01 to 3% by weight, and more preferably 0.01 to 1.5% by weight, even if subjected to a lot of heat history such as heat treatment in the can making process and retort treatment after can making. It is desirable for maintaining good impact resistance. This is considered to improve the resistance to oxidative decomposition at 200 ° C. or more, and 0.0001 to 1% by weight of a known antioxidant may be added.

When the content of the diethylene glycol component is less than 0.01, the polymerization process becomes complicated and it is not preferable in terms of cost. When it exceeds 5% by weight, the polyester is deteriorated due to the heat history in the can making process and the impact resistance is deteriorated. Tends to get worse. Diethylene glycol is generally produced as a by-product during the production of polyester, but in order to reduce the amount, the polymerization time is shortened, a method of limiting the amount of an antimony compound, a germanium compound, etc. used as a polymerization catalyst, liquid phase polymerization. Examples of the method include, but are not limited to, a method in which solid phase polymerization is combined with a solid phase polymerization, and a method in which an alkali metal component is contained.

In order to improve the taste characteristics, the content of acetaldehyde in the polyester is preferably 30 p.
pm or less, further preferably 25 ppm or less, more preferably 20 ppm or less. If the content of acetaldehyde exceeds 30 ppm, the taste characteristics are poor. The method for controlling the content of acetaldehyde in the polyester to 30 pm or less is not particularly limited, but for example, in order to remove acetaldehyde generated by thermal decomposition when the polyester is produced by a polycondensation reaction or the like, the polyester may be used under reduced pressure or A method of heat-treating at a temperature not higher than the melting point of polyester in an inert gas atmosphere, preferably a method of solid-phase polymerizing polyester at a temperature not lower than 150 ° C. and not higher than the melting point under reduced pressure or in an inert gas atmosphere, vent-type extruder And a method of performing extrusion in a short time at a melting point of + 30 ° C. or less, more preferably at a melting point of + 25 ° C. or less.

In order to improve impact resistance and taste characteristics in the present invention, the intrinsic viscosity [η] of the polyester is preferably 0.7 or more, more preferably the intrinsic viscosity [η] is 0.75. Above, more preferably [η] is 0.8
It is considered that the above is because the entanglement density of the polymer molecular chains is increased, but the impact resistance and the taste characteristics can be further improved, which is preferable.

When the polymer-coated metal laminate of the present invention is used for beverages and food cans, the polyester preferably contains 1 to 500 ppm of a germanium element in terms of taste characteristics, more preferably 5 to 300 ppm, More preferably, it is 10 to 100 ppm. If the content of germanium element is less than 1 ppm, the effect of improving the taste characteristics is not sufficient, and if it exceeds 500 ppm, foreign matter is generated in the polyester to deteriorate the impact resistance and the taste characteristics. The polyester of the present invention can have improved taste characteristics by containing the above-mentioned specific amount of germanium element in the polyester. The method of incorporating the germanium element into the polyester may be any conventionally known method and is not particularly limited, but usually, at any stage before the completion of the production of the polyester, a germanium compound may be added as a polymerization catalyst. preferable. As such a method, for example, a method of directly adding a powder of germanium compound, or Japanese Patent Publication No.
As described in JP-A-4-22234, a method in which a germanium compound is dissolved in a glycol component as a starting material of polyester and then added can be mentioned. Examples of the germanium compound include germanium dioxide, germanium hydroxide containing water of crystallization, or germanium tetramethoxide, germanium tetraethoxide, germanium tetrabutoxide, germanium alkoxide compounds such as germanium ethylene glycoloxide, germanium phenolate, germanium β-naphtholate, etc. Examples thereof include phosphorus-containing germanium compounds such as germanium phenoxide compounds, germanium phosphate and germanium phosphite, and germanium acetate. Of these, germanium dioxide is preferable.

From the viewpoint of taste characteristics, the polyester of the present invention preferably has an oligomer content of 2% by weight or less, more preferably 1.5% by weight or less, and even more preferably 1.0% by weight or less. . Here, the amount of oligomer is determined by dissolving polyester in orthochlorophenol and
Molecular weight of 8 by (gel permeation chromatograph)
An amount of 00 or less was calculated and calculated. If the oligomer content in the polyester exceeds 2% by weight, the taste characteristics are inferior, which is not preferable. The method for adjusting the content of the oligomer in the polyester to 2% by weight or less is not particularly limited, but a method similar to the method for reducing the acetaldehyde content in the above-mentioned copolymerized polyester, a transesterification catalyst, and phosphorus. This can be achieved by adopting a method of adjusting the addition amount of the compound.

The polyester of the present invention can be produced by any conventionally known method and is not particularly limited. For example, a case will be described where polyethylene terephthalate is copolymerized with an isophthalic acid component and germanium dioxide is added as a germanium compound. Transesterify or esterify terephthalic acid component, isophthalic acid component and ethylene glycol, then add phosphorus compounds such as germanium dioxide and phosphoric acid, and then continue polycondensation reaction under high temperature and reduced pressure until constant diethylene glycol content is reached. Then, a germanium element-containing polymer is obtained. Then, the obtained polymer is subjected to a solid-state polymerization reaction at a temperature below its melting point under reduced pressure or in an inert gas atmosphere to reduce the content of acetadeldide to obtain a predetermined intrinsic viscosity [η] and a carboxyl end group. Etc. can be mentioned.

In producing the polyester of the present invention,
Conventionally known reaction catalysts and anti-coloring agents can be used, and examples of the reaction catalysts include alkali metal compounds, alkaline earth metal compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium. Examples of the anti-coloring agents such as compounds include phosphorus compounds. The polybutylene terephthalate to be blended is produced in the same manner.

In the present invention, the polyester A and the polyester B may differ in the catalyst, the amount of diethylene glycol, and the amount of carboxyl end groups. When recovering the polymer, it is preferable to recover it in the (I) layer from the viewpoint of taste characteristics.

The thickness of the coated polymer of the present invention is preferably 5 to 50 μm, more preferably 8 in terms of moldability after being laminated on a metal, film formability with respect to the metal, impact resistance, and taste characteristics. ~ 45 μm, more preferably 1
It is 0 to 40 μm.

Further, as the laminated polymer, the ratio of the thickness of the (I) layer to the thickness of the (II) layer is 20: 1 to 1:20.
(I: II) is preferable in terms of taste characteristics and impact resistance, and particularly 20: 1 to 1: 1 (I: II) on the inner surface of the can is preferable in terms of taste characteristics and impact resistance. .

When the polymer-coated metal laminate of the present invention is used on the inner surface of a can, in order to improve the processability, 0.01 and 5% of inorganic particles and / or organic particles having an average particle diameter of 0.1 to 5 μm are used. It may be contained in an amount of from 10 to 10% by weight, or may be particle-free. However, it is not preferable to use particles having an average particle size of more than 5 μm because defects in the polymer layer are likely to occur. In particular, it is not preferable to include particles with a size of 30 μm or more.
It is preferable to use a material that can drastically reduce foreign matter of m or more. Examples of the inorganic particles and / or organic particles include wet and dry silica, colloidal silica, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin, clay and the like inorganic particles and styrene, silicone, acrylic acid, Examples thereof include organic particles containing divinylbenzene or the like as a constituent component. Among them, inorganic particles such as wet and dry colloidal silica and alumina, and organic particles having styrene, silicone, acrylic acid, methacrylic acid, polyester, divinylbenzene and the like as constituent components can be mentioned. Two or more kinds of these inorganic particles and / or organic particles may be used in combination.

The particles may be added to either the (I) layer or the (II) layer, but it is preferable to add the particles to the (II) layer in order to improve the processability. On the other hand, particles may be added to the (I) layer as long as the characteristics are not impaired in terms of recovery.

Further, in producing the coated polymer of the present invention, additives such as a plasticizer, an antistatic agent and a weathering agent can be appropriately used if necessary.

The method of coating the polymer on the metal body of the present invention is not particularly limited as long as it is melt extrusion lamination, but an example of the production method of the present invention will be described with reference to an example of the polymer laminated coating metal body.

As the polyester A, 12 mol% of isophthalic acid copolymerized polyethylene terephthalate and polybutylene terephthalate are used in a weight ratio of 85:15, polyester B.
As polyethylene terephthalate as twin-screw vent type separate extruder (extruder temperature is set to melting point + 20 ° C ((I) layer side is set to melting point + 20 ° C with respect to high temperature side when polyester has multiple melting points)) And melted, and then laminated in two layers with a feed block (set at 275 ° C.) and discharged from the die, so that the (I) layer becomes a metal surface.
A 30 μm thick polymer laminate is applied to a metal plate having a thickness of about 3 mm. Immediately thereafter, it is cooled and solidified with water or the like to near room temperature to obtain a polymer multilayer coated laminated metal body. Also,
It is preferable to apply a dustproof treatment to the laminating step because polymer defects are less likely to occur.

The metal body of the present invention is not particularly limited,
A metal plate made of iron, aluminum or the like is preferable in terms of formability. Furthermore, in the case of a metal plate made of iron, an inorganic oxide coating layer that improves the adhesion and corrosion resistance on the surface of the metal plate, for example, chromic acid treatment, phosphoric acid treatment, chromic acid / phosphoric acid treatment, electrolytic chromic acid treatment A chemical conversion treatment coating layer represented by, for example, chromate treatment or chromium chromate treatment may be provided. Particularly, in terms of metallic chromium, 6.5 to 6.5 as chromium
150 mg / m ² of hydrated chromium oxide is preferable, and a spreadable metal plating layer such as nickel, tin, zinc, aluminum, gun metal or brass may be further provided. For tin plating 0.5 to 15 g / m ^2, it is preferable to have a plating amount when nickel or aluminum 1.8~20g / m ^2.

The polymer-coated laminated metal body of the present invention can be suitably used for coating the inner and outer surfaces of a two-piece metal can produced by drawing or ironing. Also, it can be preferably used for covering the lid portion of a two-piece can or the body, lid and bottom of a three-piece can because it has good metal adhesion, moldability and impact resistance.

In particular, the colored polymers of the invention can be used for coating the outer surface. Therefore, a colorant can be blended in the polyester layer, a white colorant is preferably used as the colorant, and a colorant selected from titanium oxide, zinc white, inorganic or organic pigments is preferably 10 to 6
It is desirable to add 0% by weight, more preferably 15 to 50% by weight. If the addition amount is less than 10% by weight, the color tone and whiteness are deteriorated, which is not preferable. You may use together a pinking agent, a bluing agent, etc. as needed. The organic pigment may be contained in either the polyester A and / or the polyester B, but it is preferable that the organic pigment is contained in a large amount in the viewpoint of the durability of the coating polymer. In particular, a method in which polybutylene terephthalate is allowed to contain particles of titanium oxide or the like at a high concentration and diluted with another polyester is preferable for obtaining a high molecular weight white polymer-coated metal body. In that case, the layer (II) is used as a metal laminating surface. It is preferable to do so from the viewpoint of adhesiveness. The polymer may be a single layer or a laminated layer, but as a laminated polymer, the ratio of the thickness of the (I) layer to the thickness of the (II) layer is 1: 1 to 50: 1 (I: I).
I) is preferable in terms of whiteness and can-making property, and particularly preferably 2: 1 to 20: 1 (I: II) in terms of whiteness and can-making property.

[0039]

[Measurement and Evaluation Method of Characteristics] The characteristics were measured and evaluated by the following methods.

(1) Content of diethylene glycol component in polyester It was measured by NMR (13 C-NMR spectrum).

(2) Content of Germanium Element in Polyester The content of germanium element in the polyester composition and the peak intensity were quantified by fluorescent X-ray measurement.

(3) Intrinsic viscosity of polyester Dissolve polyester in orthochlorophenol,
It was measured at ° C. The insoluble polymer was filtered off and measured.

(4) Melting point of polyester Crystallized polyester was subjected to a differential scanning calorimeter (DSC-2 type manufactured by Perkin Elmer Co., Ltd.) at 10 ° C./min.
The heating rate was measured.

(5) Content of acetaldehyde in polyester Polyester fine powder (2 g) was collected, charged into a pressure vessel together with ion-exchanged water, extracted with water at 120 ° C. for 60 minutes, and then quantified by high-sensitivity gas chromatography to determine the amount of acetaldehyde in the polyester. I asked.

(6) Carboxyl terminal group (equivalent / ton) The polyester was dissolved in o-cresol / chloroform (weight ratio 7/3) at 90 to 100 ° C. for 20 minutes, and potentiometric titration was carried out with an alkali.

(7) Amount of oligomer of polyester 1 g of polyester was dissolved in orthochlorophenol,
The amount of components having a molecular weight of 800 or less was determined by GPC (gel permeation chromatograph) as the amount of oligomers based on the total amount.

(8) Impact resistance A tin steel sheet heated to 100 to 350 ° C. and coated with a polymer on a tin steel sheet having a chromate treatment applied to the outer surface of the can of 2.8 g / m ² and the inner surface of the can of 100 mg / m ² After that, it is molded with an ironing machine (molding ratio (maximum thickness / minimum thickness) = 3.0) and bottom molding is performed. Draw Ironing
Got a can

(Impact resistance in carbonated drinks) 220 after can making
Heat treatment at ℃ for 10 minutes, and fill with carbonated water at 0 ℃, 48
Carbonated bubbling for an hour. Then, after punching each 5 points from the outside of the can bottom with a punch, the contents were removed and the inside of the can was masked with wax, and 1% saline was put into the cup,
A voltage of 6 V was applied to the electrode in the saline solution and the metal can, and the current value was read to obtain the average value of 5 cans.

Class A: less than 0.1 mA Class B: 0.1 mA or more and less than 0.2 mA Class C: 0.2 mA or more and less than 0.5 mA Class D: 0.5 mA or more

(Impact resistance in retort beverages) 2 after canning
Bake at 20 ℃ for 10 minutes, and after baking at 20 ℃
× Retort treatment for 30 minutes, fill with commercially available oolong tea, leave at 30 ° C for 24 hours, impact with 5 points each from the outside of the can bottom with a punch, then remove the contents and mask the inside of the can with wax. Then, 1% saline solution was put in the cup, a voltage of 6 V was applied to the electrode and the metal can in the saline solution, the current value was read, and the average value of 5 cans was determined.

Class A: less than 0.1 mA Class B: 0.1 mA or more and less than 0.2 mA Class C: 0.2 mA or more and less than 0.5 mA Class D: 0.5 mA or more

(9) Taste characteristics A fragrance aqueous solution (d-limonene 30 p only on the polymer (II) layer side)
(contact area: 314c)
m ² ) After standing at 20 ° C. for 7 days, the components that were heated and expelled at 80 ° C. for 30 minutes in a nitrogen stream were quantified by gas chromatography to determine the adsorbed amount of d-limonene per 1 g of the film, and the taste characteristics were evaluated.

Further, an aqueous fragrance solution (d-
Limonene (20 ppm aqueous solution) was put therein, and after sealing, the mixture was left for 1 month, then opened and the sensory test evaluated the change of odor according to the following criteria.

Class A: No change in odor is observed B Class: Almost no change in odor C Class: Change in odor is observed

[0055]

The present invention will be described in detail below with reference to examples.

Example 1 As Polyester A, 12 mol% of isophthalic acid copolymerized polyethylene terephthalate (direct weight method (phosphoric acid: phosphorus element content 60 ppm), germanium element content 40 ppm,
[Η] = 0.88, diethylene glycol 0.70% by weight, melting point 228 ° C., carboxyl end group: 12 equivalent / ton, and polybutylene terephthalate ([η] = 0.9).
5, melting point 223 ° C., carboxyl end group: 32 equivalents / ton in weight ratio of 85:15, Polyester terephthalate as polyester B (direct weight method (trimethyl phosphate:
Phosphorus element amount 60ppm), Germanium element amount 40pp
m, [η] = 0.90, diethylene glycol 0.89
% By weight, melting point 253 ° C., carboxyl end group: 7 equivalents /
2 tons) of twin-screw vent type separate extruders (extruder temperature is melting point + 20 ° C ((I) layer side is higher melting point + melting point +2)
(Set to 0 ° C.) and melted, and then stacked in two layers ((I) layer / (II) layer = 8/2, set temperature 270 ° C.) in a feed block and discharged from a normal die A steel plate having a thickness of 0.3 mm, which was once cast on a cooling roll with the (II) layer as the roll surface and was immediately heated to about 150 ° C. so that the (I) layer could become the adhesive surface 2.8 g / m ^{2 on} the side and 100 mg / m ² on the inner surface of the can, which was subjected to chromate treatment, was extrusion laminated (nip pressure at that time was about 80 kg / cm, laminating speed was 100 m / min), and immediately Quenched in a water tank. The thus obtained two-layer laminated coating polymer was obtained by dissolving the polyester component in a solvent to obtain an intrinsic viscosity of 0.81, an oligomer amount of 0.80% by weight and an acetaldehyde amount of 18 pp.
m and a carboxyl terminal group were 24 equivalents / ton. Table 1 shows the physical properties and the results obtained by laminating on a metal plate and making a can. As can be seen from the table, the polymer multilayer coated metal laminate of the present invention containing an appropriate amount of butanediol component was particularly excellent in both impact resistance and taste characteristics.

Examples 2 to 12 The amount of butanediol residue, the lamination ratio, the type of polyester, the type of metal plate, etc. were changed and extrusion lamination was performed on the metal plate in the same manner as in Example 1. The results are shown in Tables 1 to 4.

In Example 2, a polymer multilayer coated metal laminate was obtained in the same manner as in Example 1 except that the blending amount of 12 mol% isophthalic acid copolymerized polyethylene terephthalate and polybutylene terephthalate was 70:30 by weight. It was As shown in Table 1, particularly good characteristics were obtained.

In Example 3, a polymer-coated metal laminate was obtained in the same manner as in Example 1 except that only the (I) layer was extrusion laminated. As shown in Table 1, the adsorption amount increased slightly, but good characteristics were obtained.

In Example 4, as polyester A, 10 mol% of isophthalic acid copolymerized polyethylene terephthalate (direct weight method (trimethyl phosphate: phosphorus content 60 ppm), germanium element content 42 ppm, [η] = 0.85, diethylene glycol 0. 70% by weight, melting point 234 ° C., carboxyl end group: 9 equivalents / ton), polybutylene terephthalate in a weight ratio of 90:10, polyester B as a copolyester shown in Table 2, and the lamination ratio being changed. A polymer multilayer coated metal laminate was obtained in the same manner as in 1. As shown in Table 2, good characteristics were obtained.

In Example 5, a polymer multilayer coated metal laminate was obtained in the same manner as in Example 1 except that the amount of carboxyl end groups in the polyester raw material was increased. As shown in Table 2, the impact resistance was slightly lowered.

In Example 6, a polymer multi-layer coated metal laminate was obtained in the same manner as in Example 1 except that the amount of diethylene glycol in the polyester was increased. As shown in Table 2, the impact resistance was slightly lowered.

In Example 7, a polymer multilayer coated metal laminate was obtained in the same manner as in Example 1 except that the intrinsic viscosity of the raw material polyester was reduced, the extrusion temperature was 285 ° C., and the polymer chips were extruded by a single screw extruder. It was As shown in Table 3, the content of acetaldehyde was large and the intrinsic viscosity of the film was small, so that impact resistance and taste characteristics were slightly deteriorated.

In Example 8, particles were added to polyester B, extrusion lamination was performed using TFS (tin-free) steel sheet in the same manner as in Example 1, and then the obtained polymer multilayer-coated metal body was deep-drawn. (Molding ratio: 1.3 (maximum thickness /
The minimum thickness)) was evaluated and good characteristics were obtained as shown in Table 3.

In Example 9, polybutylene terephthalate ([η] = 0.65, melting point 222 ° C.) containing 70% by weight of rutile-type titanium oxide was formed on the surface opposite to the laminated surface after extrusion lamination of Example 1. , Carboxyl end group 45 equivalent / ton) and polyethylene terephthalate (direct weight method (phosphoric acid: phosphorus element amount 60 ppm), germanium element amount 42 ppm, [η] = 0.85, diethylene glycol 0.8% by weight, melting point 258 ° C., Carboxyl end groups: 10 equivalents / ton) were blended in a weight ratio of 1: 1 to form polyester A ((I) layer), and polyester B ((II) layer) was isophthalic acid 12 mol% copolymerized polyethylene. Terephthalate (transesterification catalyst: calcium acetate (calcium element amount 70 ppm), phosphoric acid: phosphorus amount 50 ppm, gel Maniumu element amount 40pp
m, [η] = 0.88, diethylene glycol 0.70
% By weight, melting point 228 ° C., carboxyl end group: 12 equivalents / ton, 2 layers ((I) layer / (II) layer = 8 /
2) and then cast on a cooling roll with the (I) layer as the roll surface, and immediately extruded and laminated so that the (II) layer becomes the adhesive surface, and the polymer multi-layer coated metal body was deepened in the same manner as in Example 7. As a result of drawing molding (molding ratio: 1.3 (maximum thickness / minimum thickness)) and evaluating, not only the outer surface of the can exhibited good whiteness but also good properties as shown in Table 3 were obtained.

In Example 10, 0.05% by weight of "Irganox" 1010 manufactured by Ciba-Geigy was added to the (I) layer without changing the thickness of the steel sheet to aluminum, and the thickness,
A polymer multilayer coated metal laminate was obtained in the same manner as in Example 1 except that the lamination ratio was changed. As shown in Table 4, good characteristics were obtained.

Comparative Example 1 As the (I) layer, 17.5 mol% of isophthalic acid copolymerized polyethylene terephthalate (ester exchange catalyst: calcium acetate (calcium element content 70 ppm), phosphoric acid: phosphorus content 50 ppm, germanium element content 50 ppm, [η ]
= 0.65, diethylene glycol 2.0% by weight, melting point 211 ° C, acetaldehyde amount 37 ppm, carboxyl end group 41 equivalent / ton), 5 mol% isophthalic acid copolymerized polyethylene terephthalate (transesterification catalyst: calcium acetate) as layer (II) (Calcium element amount 70p
pm), phosphoric acid: phosphorus amount 55 ppm, germanium element amount 42 ppm, [η] = 0.64, diethylene glycol 1.20 wt%, melting point 239 ° C., carboxyl terminal group 39 equivalent / ton, average particle diameter 4 μm silicon oxide particles 0.
1% by weight) and the extrusion temperature was 285 ° C. to obtain a polymer multilayer-coated metal laminate with a single-screw extruder. The results are shown in Table 4.

This polymer multi-layer coated metal laminate did not contain a butanediol component and had a large amount of acetaldehyde, so the characteristics were deteriorated.

Comparative Example 2 A polymer-coated metal laminate was obtained in the same manner as in Example 3 except that polyester A was polybutylene terephthalate. The results are shown in Table 4. As can be seen from the table, the taste characteristics were greatly reduced.

[0070]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[0071]

The polymer-coated metal laminate metal sheet of the present invention is excellent in impact resistance and taste characteristics when formed into a can or the like,
In particular, it has excellent impact resistance even after heat treatment such as baking and retort, and can be suitably used for a metal can manufactured by molding.

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Claims (6)

[Claims] 1. A molar ratio of ethylene glycol residue and butanediol residue is 20:80 to 95: 5, and a molar ratio of terephthalic acid residue and isophthalic acid residue is 50:50 to 10.
A polymer-coated metal laminate, which is obtained by coating a layer (I) of polyester A having a melting point of 120 to 265 ° C., which is blended in a ratio of 0: 0, by extrusion lamination. 2. An ethylene glycol residue and a butanediol residue in a molar ratio of 20:80 to 95: 5, and a terephthalic acid residue and an isophthalic acid residue in a molar ratio of 50:50 to 10.
A layer (I) made of polyester A having a melting point of 120 to 265 ° C. and blended at a ratio of 0: 0 and a layer (II) made of polyester B having a melting point difference of the polyester A within 50 ° C. are formed by extrusion lamination. A polymer-coated metal laminate characterized by being coated. 3. The polymer-coated metal laminate according to claim 1, wherein the polyester component has a carboxyl terminal group amount of 40 equivalents / ton or less. 4. The polymer-coated metal laminate according to claim 1, wherein the polyester component has a diethylene glycol component content of 0.01 to 5% by weight. 5. The polymer-coated metal laminate according to claim 1, wherein the polyester component has an acetaldehyde amount of 30 ppm or less. 6. The intrinsic viscosity [η] of the polyester component is 0.7 or more, wherein the intrinsic viscosity [η] is 0.7 or more.
A polymer-coated metal laminate according to any one of the claims.