JP3284741B2 - Polymer multilayer coated metal laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer polymer-coated metal laminate. More specifically, the present invention relates to a polymer multilayer-coated metal laminate excellent in moldability, impact resistance and taste characteristics and suitable for a metal can produced by molding.

[0002]

2. Description of the Related Art Conventionally, the inner and outer surfaces of a metal can are coated with various thermosetting resins, such as epoxy and phenol, dissolved or dispersed in a solvent to prevent corrosion. Has been widely practiced. However, such a method of coating the thermosetting resin requires a long time for drying the paint, and has unfavorable problems such as a decrease in productivity and environmental pollution due to a large amount of an organic solvent.

As a method for solving these problems, there is a method of extruding and laminating a polymer on a steel plate, an aluminum plate, or a metal plate obtained by subjecting the metal plate to various surface treatments such as plating. When a metal can is manufactured by drawing or ironing a polymer laminated metal plate, the polymer laminated metal plate 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 does not peel off from the metal plate, and cracks and pinholes do not occur due to impact on the metal can.

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

Many proposals have been made to solve these demands. For example, Japanese Patent Application Laid-Open No. Sho 51-17988 discloses a metal body obtained by extrusion laminating a polyethylene terephthalate polymer having a crystallinity of 20% or less. 51-1
No. 48755 discloses a metal body obtained by extruding and laminating a polymethylene terephthalate-based polymer on a metal body heated to 200 to 350 ° C.
A metal body or the like is disclosed in which a multilayer polyester is extrusion-laminated on a metal body heated to less than 0 ° C. However, these proposals do not comprehensively satisfy the above-described various required characteristics, and cannot be said to be at a level that is sufficiently satisfactory particularly in terms of achieving both impact resistance and taste characteristics. Was.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and is excellent in moldability, impact resistance and taste characteristics, and in particular, to achieve both impact resistance and taste characteristics. An object of the present invention is to provide a polymer multilayer-coated metal laminate suitable for a metal can produced by excellent molding.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polymer having a melting point of 1: 1.
The polyester A having an ethylene terephthalate and / or ethylene isophthalate of 40 to 245 ° C. and / or ethylene isophthalate as a main component is 60:40 to 40:40 by weight.
(I) layer blended at a ratio of 97: 3 and a melting point of 22
This can be achieved by a polymer multilayer-coated metal laminate characterized in that a layer (II) of polyester B containing ethylene terephthalate as a main component at 0 to 265 ° C is coated by extrusion lamination.

The present invention relates to a process for laminating a polyester having a specific melting point, mixing a low-melting polyester with an appropriate amount of an olefin-based polymer, extruding and laminating a metal, and then molding and forming the can. It has been found that good impact resistance can be obtained even when subjected to many heat histories such as heat treatment at room temperature and retort treatment after can making. The effect is much greater than that of the prior art in that not only compatibility of impact resistance and taste characteristics can be achieved, but also impact resistance can be dramatically improved.

In the present invention, the polyester having ethylene terephthalate and / or ethylene isophthalate as a main component is 50 mol% of the polyester component.
The above refers to polyesters which are ethylene terephthalate and / or ethylene isophthalate, preferably 6
A polyester in which 0 mol% or more is ethylene terephthalate and / or ethylene isophthalate.

Here, the polyester is a polymer comprising a dicarboxylic acid component and a glycol component, and other dicarboxylic acid components such as naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfondicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodium Aromatic dicarboxylic acids such as sulfoisophthalic acid and phthalic acid, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid and fumaric acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid And a dicarboxylic acid component arbitrarily selected from oxycarboxylic acids such as p-oxybenzoic acid and the like. On the other hand, as the glycol component, as components other than ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, aliphatic glycols such as neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, bisphenol A,
Aromatic glycols such as bisphenol S may be copolymerized. Of the glycol components, butanediol is preferred from the viewpoint of improving impact resistance. In addition, two or more of these dicarboxylic acid components and glycol components may be used in combination.

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

The polyester A used in the present invention has a heat resistance of 140 to 245 ° C. as a melting point,
It is necessary in terms of sufficient adhesiveness to a metal plate, and also in terms of suppressing decomposition of the olefin polymer when mixed with the olefin polymer. Preferably, copolymerized polyesters such as isophthalic acid copolymerized polyethylene terephthalate, butanediol / isophthalic acid copolymerized polyethylene terephthalate, and diethylene glycol as the polyester
Examples include polyesters obtained by copolymerizing polyoxyethylene glycol such as polyethylene glycol.

The olefin polymer to be mixed with the polyester A is not particularly limited, but includes low density, medium density, high density polyethylene, linear low density polyethylene, ultrahigh molecular weight polyethylene, polypropylene, ethylene-propylene copolymer, Examples include ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ionomer, olefin-vinyl alcohol copolymer such as ethylene-vinyl alcohol copolymer, and amorphous polyolefin. Particularly, an ethylene-vinyl alcohol copolymer and an amorphous polyolefin are preferable because they have excellent impact resistance after retort treatment.

Here, the olefin-vinyl alcohol copolymer is generally a copolymer obtained by saponifying a copolymer of an olefin and a vinyl ester such as vinyl acetate, and particularly has an olefin content of 10 to 60. Mole%, especially 20 to 50 mol% of olefin-vinyl alcohol copolymer is suitable for greatly improving impact resistance. Further, those having a saponification degree of 90% or more are preferable in view of thermal stability.

Here, the amorphous polyolefin is generally such that its crystalline melting point is hardly observed by heat measurement. Representative examples of the amorphous polyolefin in the present invention include hydrides of dicyclopentadiene and dicyclopentadiene. It refers to at least one selected from a hydride of a copolymer of pentadiene and ethylene, a hydride of a copolymer of a reaction product of dicyclopentadiene and ethylene, and a norbornene-based polymer.

The olefin polymer preferably has a melt index of 0.1 to 50 g / 10 minutes at 210 ° C. and a load of 2160 g, more preferably 0.5 to 30 g, in view of melt extrudability with the polyester A. / 10 minutes,
Particularly preferably, it is 1 to 20 g / 10 minutes.

It is preferable to add a known compatibilizer to the mixed layer of the polyester A and the olefin polymer to improve the compatibility since the impact resistance is improved.

In the present invention, there is provided a layer (I) in which the polyester A and the olefin-based polymer are blended in a weight ratio of 60:40 to 97: 3 in terms of simultaneously satisfying impact resistance and taste characteristics. It is necessary. More preferably, the weight ratio of the polyester A and the olefin polymer is 70:
30-95: 5, more preferably 75: 25-92: 8 by weight ratio of polyester A and olefin polymer. As described above, the impact resistance is greatly improved by including the olefin polymer which is considered to be excellent in flexibility and viscoelasticity in the polyester A.

On the other hand, in consideration of the scratch resistance in the can making process and the non-adsorption property of the fragrance component of the contents of the can, in addition to the film,
It is preferable to laminate a layer (II) made of polyester B having a melting point of 220 to 265 ° C and ethylene terephthalate as a main component. If the melting point is lower than 220 ° C., the heat resistance of the can is insufficient, which is not preferable. Here, the polyester having ethylene terephthalate as a main component refers to a polyester in which 70 mol% or more, preferably 80 mol% or more, is an ethylene terephthalate unit.

Further, polyester A and polyester B
Is preferably 35 ° C. or less, more preferably 3 ° C. or less.
When the temperature is 0 ° C. or lower, more preferably 25 ° C. or lower, the difference in thermal expansion / contraction behavior between the layer (I) and the layer (II) during the heat history during the can-making process is reduced, and the workability is improved.

In the present invention, the amount of the carboxyl terminal group of the polyester component is preferably 35 equivalents / ton or less from the viewpoint of thermal stability and taste characteristics of the polymer forming the layer (I). More preferably, the amount of carboxyl end groups is 30 equivalents /
Tons or less. Specifically, a method of reducing the amount of carboxyl terminal groups to a predetermined amount by solid-state polymerization, a known terminal blocking agent such as carbodiimide, oxazoline or the like can be preferably performed.

On the other hand, it is preferable to increase the amount of carboxyl end groups in the surface layer of the layer (I) by surface treatment or the like in order to improve the adhesiveness.

The polyester in the present invention preferably has a diethylene glycol content of 0.01 to 1.5% by weight, more preferably 0.01 to 1.0% by weight, and still more preferably 0.01 to 0.6% by weight. Is desirable in order to maintain good impact resistance even when subjected to many heat histories such as heat treatment in a can making process and retort treatment after can making. This is considered to improve the resistance to oxidative decomposition at 200 ° C. or higher.
To 1% by weight.

If the diethylene glycol component is less than 0.01, the polymerization step becomes complicated, which is not preferable in view of cost. The impact resistance is greatly deteriorated, which is not preferable. Diethylene glycol is generally produced as a by-product during the production of polyester.However, to reduce the amount, methods such as shortening the polymerization time or limiting the amount of antimony compounds, germanium compounds, etc. used as polymerization catalysts, liquid phase polymerization And a method in which an alkali metal component is contained, but the method is not particularly limited.

In order to improve the taste characteristics, the content of acetaldehyde in the polyester is preferably 30 p.
pm or less, more preferably 25 ppm or less, more preferably 20 ppm or less. When the content of acetaldehyde exceeds 30 ppm, the taste characteristics are poor. The method for reducing the content of acetaldehyde in the polyester to 30 pm or less is not particularly limited. For example, in order to remove acetaldehyde generated by thermal decomposition during production of the polyester by a polycondensation reaction or the like, the polyester is reduced under reduced pressure or A method in which heat treatment is performed at a temperature not higher than the melting point of the polyester in an inert gas atmosphere, preferably a method in which the polyester is subjected to solid-state polymerization at a temperature of not lower than the melting point and a temperature of 150 ° C. or more under reduced pressure or an inert gas atmosphere; And a method of extruding the polyester in a short time at a melting point of + 30 ° C., preferably + 25 ° C. when the polyester is melt-extruded.

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

When the polymer multilayer-coated metal laminate of the present invention is used for beverages and food cans, the polyester preferably contains 1 to 500 ppm, more preferably 5 to 300 ppm, of a germanium element from the viewpoint of taste characteristics. ,
More preferably, it is 10 to 100 ppm. If the amount of germanium element is less than 1 ppm, the effect of improving taste characteristics is not sufficient, and if it exceeds 500 ppm, foreign matters are generated in the polyester to deteriorate impact resistance and deteriorate taste characteristics. The polyester of the present invention can further improve taste characteristics by including the above-mentioned specific amount of the germanium element in the polyester. The method of causing the germanium element to be contained in the polyester can be a conventionally known arbitrary method, and is not particularly limited.However, it is usually possible to add a germanium compound as a polymerization catalyst at an arbitrary stage before the completion of the production of the polyester. preferable. As such a method, for example, a method of adding a germanium compound powder as it is, or as described in JP-B-54-22234, a method of adding a germanium compound to a glycol component which is a starting material of a polyester. Can be dissolved and added. Examples of the germanium compound include germanium dioxide, germanium hydroxide containing water of crystallization,
Alternatively, germanium alkoxide compounds such as germanium tetramethoxide, germanium tetraethoxide, germanium tetrabutoxide, germanium ethyleneglycoxide, germanium phenolate, germanium phenoxide compounds such as germanium β-naphtholate, germanium phosphate, and phosphorus such as germanium phosphite Germanium compounds, germanium acetate, and the like. Among them, germanium dioxide is preferable.

The polyester of the present invention has an oligomer content of 0.8% by weight in view of taste characteristics.
It is preferably at most 0.7% by weight, more preferably at most 0.6% by weight. 0.8% by weight of oligomer in copolymerized polyester
If it exceeds, taste characteristics are inferior and it is not preferable. The method for reducing the content of the oligomer in the polyester to 0.8% by weight or less is not particularly limited, but a method similar to the above-described method for reducing the acetaldehyde content in the copolymerized polyester may be employed. Can be achieved.

For the production of the polyester of the present invention, any conventionally known method can be employed and is not particularly limited. For example, a case will be described in which an isophthalic acid component is copolymerized with polyethylene terephthalate and germanium dioxide is added as a germanium compound. The terephthalic acid component, isophthalic acid component and ethylene glycol are subjected to transesterification or esterification reaction, and then germanium dioxide and a phosphorus compound are added, followed by a polycondensation reaction at a high temperature and reduced pressure until a constant diethylene glycol content is reached, and the germanium element A containing polymer is obtained.
Then, the obtained polymer was subjected to solid-state polymerization under a reduced pressure or an inert gas atmosphere at a temperature equal to or lower than its melting point,
Examples thereof include a method of reducing the content of acetoaldehyde to obtain a predetermined intrinsic viscosity [η] and a carboxyl terminal group.

In producing the polyester of the present invention,
Conventionally known reaction catalysts and coloring inhibitors can be used. Examples of the reaction catalyst include alkali metal compounds, alkaline earth metal compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, and titanium. Examples of the coloring inhibitor such as a compound include a phosphorus compound.

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

The thickness of the coating polymer of the present invention is preferably from 5 to 50 μm, more preferably from 8 to 50 μm, in view of moldability after lamination to metal, film properties to metal, impact resistance and taste characteristics. ~ 45 μm, more preferably 1
0 to 40 μm.

Further, as the laminated polymer, the ratio of the thickness of the layer (I) to the thickness of the layer (II) is 20: 1 to 1: 1 (I:
II) is preferred from the viewpoint of taste characteristics and impact resistance, and particularly preferably from 15: 1 to 4: 1 (I: II) from the viewpoint of impact resistance.

The polymer of the present invention may contain 0.01 to 10% by weight of inorganic and / or organic particles having an average particle diameter of 0.1 to 10 μm in order to improve processability. Particle-free may be used. However, it is not preferable to use particles having an average particle diameter of more than 10 μm because defects in the polymer layer are likely to occur. In particular, since it is not preferable to contain particles having a size of 30 μm or more, it is preferable to use a filter capable of drastically reducing foreign substances having a size of 30 μm or more as an extruder. Examples of the inorganic particles and / or organic particles include inorganic particles such as wet and dry silica, colloidal silica, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin, and clay, and styrene, silicone, acrylic acid, and the like. Organic particles containing divinylbenzene or the like as a constituent component can be exemplified. Among them, wet and dry colloidal silica, inorganic particles such as alumina and styrene, silicone, acrylic acid, methacrylic acid, polyester,
Organic particles containing divinylbenzene or the like as a constituent component can be exemplified. Two or more 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 workability. On the other hand, particles may be added to the layer (I) as long as the properties are not impaired in terms of recovery and the like.

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

It is preferable to improve the adhesiveness by subjecting the layer (I) to a surface treatment such as a corona discharge treatment in order to further improve the characteristics. At this time, the E value is preferably 5 to 40, and more preferably 10 to 25.

The method for coating the metal body with the polymer multilayer according to the present invention is not particularly limited as long as it is a melt extrusion laminate, but an example of the production method of the present invention will be described.

As polyester A, isophthalic acid 17.
5 mol% copolymerized polyethylene terephthalate ([η] =
0.84, 0.7% by weight of diethylene glycol, melting point 2
15 ° C., carboxyl end groups: 15 equivalents / ton) and ethylene-vinyl alcohol copolymer (ethylene content 29
Mol%, melting point 183 ° C., MFI: 8 g / 10 min (210
2160 g)) in a weight ratio of 95: 5, as a polyester B, 5 mol% of isophthalic acid copolymerized polyethylene terephthalate ([η] = 0.90, diethylene glycol 0.89 wt%, melting point 240 ° C., carboxyl end group:
(14 eq / ton) to a separate twin-screw vented extruder (the extruder temperature is set to the melting point + 25 ° C (the melting point of the (I) layer side is + 30 ° C for the polyester)) and melted. After laminating two layers with a feed block (set at 275 ° C.) and discharging from a die, a 30 μm thick polymer laminate is applied to a metal plate having a thickness of about 0.3 mm so that the layer (I) becomes a metal surface. Immediately thereafter, the mixture is solidified by cooling to near normal temperature with water or the like to obtain a polymer multilayer-coated laminated metal body. Further, it is preferable to perform a dustproof treatment in the laminating step, since it is difficult to cause a defect of the polymer.

Although the metal body of the present invention is not particularly limited,
From the viewpoint of formability, a metal plate made of iron, aluminum, or the like is preferable. Further, in the case of a metal plate made of iron, an inorganic oxide coating layer on the surface thereof for improving adhesion and corrosion resistance, 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, a chromate treatment or a chromium chromate treatment may be provided. In particular, in terms of chromium metal, 6.5 to chrome
A chromium hydrated oxide of 150 mg / m ² is preferable, and a spreadable metal plating layer such as nickel, tin, zinc, aluminum, gunmetal, brass, etc. may be provided. It is preferable that tin plating has a plating amount of 0.5 to 15 g / m ² , and nickel or aluminum has a plating amount of 1.8 to 20 g / m ² .

The polymer multilayer-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. In addition, good metal adhesion for covering the lid of a two-piece can, or the body, lid, and bottom of a three-piece can,
Since it has moldability and impact resistance, it can be preferably used. In particular, a colored inventive polymer can be used for outer surface coating. For this reason, a coloring agent can be blended in the polyester layer. As the coloring agent, a white coloring agent, a red coloring agent, or the like is preferably used, and a coloring agent selected from titanium oxide, zinc white, an inorganic or organic pigment, and the like is used. It is desirable to add 60% by weight, preferably 15 to 50% by weight. If the addition amount is less than 5% by weight, the color tone, whiteness and the like are inferior and are not preferred. If necessary, a pinking agent, a bluing agent and the like may be used in combination.

[0044]

[Method of measuring and evaluating characteristics] The characteristics were measured and evaluated by the following methods.

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

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

(3) Intrinsic Viscosity of Polyester Polyester is dissolved in orthochlorophenol,
Measured in ° C. The insoluble polymer was removed by filtration and measured.

(4) Melting Point of Polyester The polyester was crystallized and subjected to 10 ° C./min by a differential scanning calorimeter (DSC-2, manufactured by Perkin Elmer).
The temperature was measured at a rate of temperature rise.

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

(6) Oligomer Content in Polyester 100 mg of the polymer was dissolved in 1 ml of orthochlorophenol, the solution was separated, and then subjected to liquid chromatography (Vari).
The cyclic trimer was measured using a model 8500 (manufactured by An Corporation) and the amount was determined as the oligomer amount.

(7) Impact Resistance After coating a Sn-plated tin metal plate heated to 100 to 350 ° C. with a polymer, it was formed by an ironing machine (forming ratio (maximum thickness / minimum thickness) = 3.0). Then, the bottom molding and the like were performed to obtain a Draw Ironing can.

(Impact resistance in carbonated beverages)
Heat treatment at 0 ° C for 10 minutes,
Carbonated bubbling for hours. Then, after applying impact to each of the 5 places with a punch from the outer surface of the can bottom, the contents are removed and the inner surface of the can side is masked with a wax, and 1% saline solution is put in the cup,
A current of 6 V was applied to the electrode and the metal can in the saline solution, and the current value was read.

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)
Perform baking at 20 ° C for 10 minutes.
Perform retort treatment for 30 minutes, fill with commercially available oolong tea, leave at 30 ° C. for 24 hours, apply an impact to each of the five places with a punch from the outer surface of the can bottom, then remove the contents and mask the inner surface of the can with a wax. Then, a 1% saline solution was put into the cup, and a voltage of 6 V was applied to the electrode and the metal can in the saline solution, and the current value was read.

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 0.5 mA or less Class D: 0.5 mA or more

(9) Taste Characteristics Only the polymer (II) layer side has an aqueous fragrance solution (d-limonene 30p).
pm aqueous solution (contact area: 314c)
m ² ) After leaving to stand at normal temperature for 7 days, the components that were expelled by heating at 80 ° C. for 30 minutes in a nitrogen stream were quantified by gas chromatography to determine the amount of adsorbed d-limonene per 1 g of the film, and the taste characteristics were evaluated.

In addition, a perfume aqueous solution (d-
Limonene (20 ppm aqueous solution) was added, left for one month after sealing, then opened, and the change in odor was evaluated by a sensory test according to the following criteria.

Grade A: no change in odor B class: little change in odor C class: change in odor

[0059]

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

Example 1 As polyester A, 17.5 mol% of copolymerized polyethylene terephthalate of isophthalic acid (with a germanium element content of 4
0 ppm, [η] = 0.84, diethylene glycol 0.70% by weight, melting point 215 ° C., carboxyl end group:
15 equivalents / ton) and ethylene-vinyl alcohol copolymer (ethylene content 29 mol%, melting point 183 ° C, MF
I: 8 g / 10 minutes (210 ° C., 2160 g)) in a weight ratio of 92: 8, as polyester B, copolymerized polyethylene terephthalate of 5 mol% isophthalic acid (germanium element amount: 40 ppm, [η] = 0.90, diethylene glycol: 0. 89% by weight, melting point 240 ° C., carboxyl end group: 14 equivalents / ton, silicon oxide particles 0.2% by weight having an average particle diameter of 4 μm) and a separate twin-screw extruder (the temperature of the extruder is melting point + 25 ° C.) (The melting point of the (I) layer is set to + 25 ° C. with respect to the polyester A) and melted. Thereafter, two layers ((I) layer / (II) layer =
9/1 at a set temperature of 270 ° C.), after discharging from a normal die, a 0.3 mm-thick steel plate (Sn adhesion amount) heated and heated to about 200 ° C. so that the layer (I) becomes an adhesive surface. Is extruded on 2.8 g / m ^{2 of the} outer surface of the can and on a tin plate having a chromate treatment of 100 mg / m ² on the inner surface of the can (external lamination) (at a nip pressure of about 80 kg / cm and a laminating speed of 50 m / min). ), Immediately cooled in a water tank. The thus obtained two-layer laminated polymer was obtained by dissolving the polyester component in a solvent and determining the intrinsic viscosity. The intrinsic viscosity was 0.78, the oligomer content was 0.5% by weight, and the acetaldehyde content was 18 p.
pm, 22 equivalents / ton of carboxyl end groups. Table 1 shows the physical properties and the results of lamination on a metal plate and can making. As can be seen from the table, the polymer multilayer-coated metal laminate of the present invention containing an appropriate amount of the olefin-vinyl alcohol copolymer was particularly excellent in both impact resistance and taste characteristics.

Examples 2 to 12 Extrusion lamination was performed on a metal plate in the same manner as in Example 1 except that the amount, type, lamination ratio, polyester type, and metal plate type of the polyolefin were changed. The results are shown in Tables 1 to 4.

In Example 2, the weight ratio of the polyester A and the olefin-vinyl alcohol copolymer was 80:20.
And an olefin-vinyl alcohol copolymer having an ethylene content of 44 mol%, a melting point of 164 ° C., and an MFI of 12 g /
10 minutes (210 ° C., 2160 g), polyester B was converted to polyethylene terephthalate (germanium element amount: 40 p)
pm, [η] = 0.90, diethylene glycol 0.8
9% by weight, melting point 250 ° C., carboxyl end group: 16 equivalents / ton), and a polymer multilayer-coated metal laminate was obtained in the same manner as in Example 1 except that the laminating speed was 80 m / min. As shown in Table 1, particularly good characteristics were obtained.

In Example 3, polyester A was prepared by copolymerizing 12 mol% of isophthalic acid with polyethylene terephthalate (germanium content: 42 ppm, [η] = 0.85, diethylene glycol: 0.70 wt%, melting point: 227 ° C., carboxyl end group: 14) Equivalent / ton), polyolefin was obtained from Mitsui Petrochemical Co., Ltd. “Apel” 6509 (Norbornene-based amorphous polyolefin, heat deformation temperature 70 ° C. [ASTM
D-648, 18.6 kg / cm ² ]) and a weight ratio of 8
5:15, the lamination ratio and the particle formulation of polyester B were changed, and a polymer multilayer-coated metal laminate was obtained in the same manner as in Example 1. As shown in Table 1, particularly good characteristics were obtained.

In Example 4, polyester A was prepared by copolymerizing 10 mol% of isophthalic acid with polyethylene terephthalate (germanium content: 50 ppm, [η] = 0.72, diethylene glycol: 0.80 wt%, melting point: 235 ° C., carboxyl terminal group: 20) Equivalent / ton), polyolefin was obtained from Mitsui Petrochemical Co., Ltd. “Apel” 6015 (norbornene-based amorphous polyolefin, heat deformation temperature 125 ° C [ASTM
D-648, 18.6 kg / cm ² ]), the weight ratio was 90:10, and the particle formulation of polyester B was changed to obtain a polymer multilayer-coated metal laminate in the same manner as in Example 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 diethylene glycol in the polyester A was changed to 2.0% by weight. As shown in Table 2, good characteristics were obtained.

In Example 6, polyolefin was used as low-density polyethylene (density 0.918 g / cm ³ , melting point 108 ° C.,
A polymer multilayer-coated metal laminate was obtained in the same manner as in Example 1 except that the MFI was changed to 3 g / 10 minutes (210 ° C., 2160 g). As shown in Table 2, good characteristics were obtained.

Example 7 shows that the polyolefin is ethylene-
Vinyl acetate (5%) copolymer (density 0.926
g / cm ³ , melting point 102 ° C., MFI: 1 g / 10 min (2
A polymer multilayer-coated metal laminate was obtained in the same manner as in Example 1 except that the weight ratio was 95: 5, polyester B, and the particle formulation were changed. As shown in Table 3, good characteristics were obtained.

In Example 8, polyester A was prepared by copolymerizing 14 mol% of isophthalic acid with polyethylene terephthalate (elemental amount of antimony: 200 ppm, [η] = 0.86, diethylene glycol: 0.50 wt%, melting point: 223 ° C., carboxyl end group: 11 Equivalent / ton), polyolefin is ionomer (ethylene-methacrylic acid copolymer Zn type: melting point 99 ° C, MFI: 5 g / 10 min (210 ° C, 2
160 g)), and a polymer multilayer-coated metal laminate was obtained in the same manner as in Example 1 except that the weight ratio was 90:10. Table 3
As shown in FIG.

In Example 9, polyester A of [η] = 0.67, in which only solution polymerization was performed, and Polyester B of [η] = 0.68, in which only solution polymerization was performed, were processed at 280 ° C. using a single screw extruder. Except for extrusion, a polymer multilayer-coated metal laminate was obtained in the same manner as in Example 1. Since the obtained coated polymer had a large amount of acetaldehyde and a small intrinsic viscosity, as shown in Table 3, impact resistance and taste characteristics were slightly lowered, but good characteristics were obtained.

In Example 10, the lamination ratio was 1: 2 ((I)
Layer: (II) layer) to obtain a polymer multilayer-coated metal laminate in the same manner as in Example 1. As shown in Table 4, (II)
The impact resistance was slightly reduced due to the large lamination ratio of the layers, but good characteristics were obtained.

Example 11 was a polymer in the same manner as in Example 1 except that the type of the steel plate was aluminum, the current was heated to 150 ° C., and the layer (I) was made by adding 0.05% by weight of “Irganox” 1010 manufactured by Ciba Geigy. A multilayer coated metal laminate was obtained. As shown in Table 4, good characteristics were obtained.

In the twelfth embodiment, the following polymer 1 was prepared with a thickness of 0.
Laminate extrusion lamination on one side of 2 mm TFS steel sheet (inside of can at the time of forming), quenching, and then heat to 200 ° C again and extrude white polymer 2 below to one side of the steel sheet (outside of can at the time of forming) Lami and quenched. Furthermore, DT with a molding ratio of 1.2
R (Draw Thin Draw) molding was performed. After that, the impact resistance and taste characteristics of the can were examined.
As shown in (1), good characteristics were obtained, and the whiteness of the outer surface of the can was also good.

(Polymer 1) Laminated surface (27 μm): Polyethylene terephthalate copolymerized with 12 mol% of isophthalic acid (germanium element content 42 ppm, [η] = 0.75, diethylene glycol 0.80 wt%, melting point 228 ° C., carboxyl end group :
25 equivalents / ton) and an ethylene-vinyl alcohol copolymer (ethylene content 29 mol%) in a weight ratio of 92: 8 non-laminated surface (3 μm): isophthalic acid 5 mol% copolymerized polyethylene terephthalate (germanium element amount 4
0 ppm, [η] = 0.74, 0.89% by weight of diethylene glycol, melting point 240 ° C., carboxyl end group:
16 equivalents / ton)

(Polymer 2) Laminated surface (5 μm): 12 mol% copolymerized polyethylene terephthalate isophthalic acid (germanium element amount 4
2 ppm, [η] = 0.75, diethylene glycol 0.80% by weight, melting point 228 ° C., carboxyl end group:
25 equivalents / ton) and an ethylene-vinyl alcohol copolymer (ethylene content 29 mol%) in a weight ratio of 92: 8 non-laminated surface (25 μm): isophthalic acid 5 mol% copolymerized polyethylene terephthalate (germanium element amount 40 ppm, [Η] = 0.74, 0.89% by weight of diethylene glycol, melting point 240 ° C., carboxyl end group:
16 equivalents / ton) and titanium dioxide (average particle size 0.3μ)
m) 70% by weight of polybutylene terephthalate ([η] = 0.75, melting point 221 ° C.) in a weight ratio of 1: 2

COMPARATIVE EXAMPLE 1 17.5 mol% of copolymerized polyethylene terephthalate (germanium element content: 50 pp) was used as the (I) layer.
m, [η] = 0.65, diethylene glycol 2.0% by weight, melting point 211 ° C., acetaldehyde amount 37 ppm,
(Equivalent of carboxyl end group: 41 equivalent / ton), 5 mol% of isophthalic acid copolymerized polyethylene terephthalate (42 ppm of germanium element, [η] = 0.6) as (II) layer
4, diethylene glycol 1.20% by weight, melting point 239
° C, carboxyl end group 39 equivalents / ton, average particle size 4
μm silicon oxide particles (0.1% by weight) at an extrusion temperature of 28
At 0 ° C., a polymer multilayer-coated metal laminate was obtained in the same manner as in Example 1. Table 5 shows the results.

This polymer multilayer-coated metal laminate did not contain a polyolefin and had a large amount of acetaldehyde, so that its properties were deteriorated.

COMPARATIVE EXAMPLE 2 The same procedure as in Example 1 was repeated except that the amount of polyolefin was 1% by weight, the amount of diethylene glycol was 2.5% by weight, and [η] = 0.64. I got Table 5 shows the results.

As can be seen from the table, the polyolefin content was insufficient, and the impact resistance and taste characteristics were reduced.

Comparative Example 3 Polyester A and low-density polyethylene as polyolefin (density 0.918 g / cm ³ , melting point 108 ° C., MF
A polymer multilayer-coated metal laminate was obtained in the same manner as in Comparative Example 1 except that the weight ratio of I: 3 g / 10 min (210 ° C., 2160 g) was changed to 40:60. Table 5 shows the results.

As can be seen from the table, the amount of the polyolefin was outside the range of the present invention, and the taste characteristics were greatly reduced.

[0081]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[0082]

The metal sheet of the present invention has excellent impact resistance and taste characteristics when molded into a can or the like, and particularly has excellent impact resistance even after heat treatment such as baking or retort. And can be suitably used for metal cans manufactured by molding.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-79801 (JP, A) JP-A-4-353442 (JP, A) JP-A-54-143387 (JP, A) JP-A-7-79 290644 (JP, A) JP-A-63-17048 (JP, A) JP-A-3-274152 (JP, A) JP-A-3-155944 (JP, A) JP 2-9935 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 15/08

Claims (5)

(57) [Claims] 1. A polyester (A) having a melting point of 140 to 245 ° C. and mainly composed of ethylene terephthalate and / or ethylene isophthalate and an olefin-based polymer in a weight ratio of 60:40 to 97: 3. A polymer multilayer-coated metal laminate comprising a layer (I) and a layer (II) made of polyester B containing ethylene terephthalate having a melting point of 220 to 265 [deg.] C. as a main component, which is coated by extrusion lamination. 2. The polymer multilayer-coated metal laminate according to claim 1, wherein the amount of carboxyl end groups of the polyester component is 35 equivalents / ton or less. 3. The polymer multilayer-coated metal laminate according to claim 1, wherein the amount of the diethylene glycol component in the polyester component is 0.01 to 1.5% by weight. 4. The polymer multilayer-coated metal laminate according to claim 1, wherein the amount of acetaldehyde in the polyester component is 30 ppm or less. 5. The polyester component according to claim 1, wherein the intrinsic viscosity [η] is 0.7 or more.
The polymer multilayer-coated metal laminate according to any one of the above.