JPH1087798A - Aromatic copolyester and polyester film for lamination-processing to metal plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aromatic copolyester containing a specific copolymerization component and a specified amount of a titanium compound, capable of giving films for metal plate laminates exhibiting excellent compatibility with the copolyester and excellent in processablility and impact resistance after processed into cans. SOLUTION: This aromatic copolyester contains a 4-12C aliphatic saturated dicarboxylic acid such as adipic acid as a copolymerization component in a copolymerzation rate of e.g. 3-45mol.%, especially 10-30mol.%, based on the whole dicarboxylic acids, and contains a titanium compound (e.g. tetra-n-butyl titanate) soluble in the polymer in an amount of 30-200ppm as titanium metal. The polyester can thereby give polyester films improved in processability and impact resistance after processed into cans without deteriorating the smell retainability, heat resistance and retort resistance of conventional polyester films.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolymerized aromatic polyester and a polyester film for laminating and processing a metal plate.
A copolymerized aromatic polyester having 12 aliphatic saturated dicarboxylic acids, characterized by containing a specific amount of a titanium compound, and a copolymerized aromatic polyester having excellent compatibility with other aromatic polyesters, and By containing the copolymerized aromatic polyester, it shows excellent moldability when laminating to a metal plate and performing can making such as drawing, and has heat resistance, retort resistance, fragrance retention, and impact resistance. The present invention relates to a metal film excellent in rust prevention and the like, for example, a polyester film for a metal plate laminating process capable of producing a beverage can and a food can.

[0002]

2. Description of the Related Art Aromatic polyesters are used as materials which are very excellent in various and diverse uses such as films, fibers and molding resins. Among these aromatic polyesters, terephthalic acid-based or naphthalenedicarboxylic acid-based polyesters are known as materials excellent in physical property balance such as physical, chemical and thermal properties.

[0003] In recent years, the simplification of the process of metal cans, improvement of hygiene,
For the purpose of preventing pollution, a method of laminating a polyester film on a metal plate such as tinplate, tin-free steel, aluminum, etc. instead of an organic solvent-based coating generally applied to the inner and outer surfaces of the can, followed by drawing, etc. Many proposals have been made regarding polyester films for the lamination.

[0004] For example, JP-A-56-10451,
In Japanese Patent Application Laid-Open No. 1-192546, a biaxially oriented polyethylene terephthalate film is laminated on a metal plate via a low melting point adhesive layer, and in Japanese Patent Application Laid-Open Nos. 1-192545 and 2-57339, amorphous or extremely A low-crystalline aromatic polyester film is laminated on a metal plate. JP-A-64-22530 discloses a low-orientation and heat-set biaxially stretched polyethylene terephthalate laminated on a metal plate and used as a material for can production. However, according to the study of the present inventor, sufficient properties sufficient to balance heat resistance, molding workability, fragrance retention, aging embrittlement resistance, etc. are obtained in each case. Absent.

Japanese Patent Application Laid-Open No. 5-339348 discloses a polyester film for laminating a metal plate comprising a copolymerized polyester having a specific melting point, glass transition point and terminal carboxyl group concentration. JP-A-7-205383 discloses a specific melting point,
A polyester film for laminating and processing a metal plate laminated with a copolymerized polyester having a glass transition point, and a polyester film for metal lamination have been proposed, but according to the study of the present inventors, sufficient fragrance retention cannot be obtained. .

Further, Japanese Patent Application Laid-Open No. Hei 6-116376 proposes a polyester film for laminating and forming a metal plate comprising a copolymerized polyester containing a specific amount of an alkali metal element and a germanium element. Although it has excellent scent retention, it is hard to say that it has sufficient impact resistance. Japanese Patent Application Laid-Open No. HEI 8-112886 proposes a laminated polyester film for laminating a metal plate, comprising a layer of a copolymerized polyester containing a specific amount of an alkali metal element and having a specific melting point and a glass transition point. Although this film satisfies the required properties such as fragrance retention, impact resistance, molding processability, aging embrittlement resistance, and heat resistance to some extent, it is extremely difficult to increase the degree of freedom in the design and design of can bodies. When deep drawing and ironing at a high magnification, the formability and the like become insufficient.

The present inventor has proposed that adipic acid,
Focusing on the fact that aliphatic saturated dicarboxylic acids represented by sebacic acid and the like can easily control physical properties such as a polymer melting point and a glass transition point, and have an advantage of being easily available at a low cost. In order to solve the above-mentioned insufficiency of properties by copolymerizing the above, it was clarified that the properties alone were insufficient.

On the other hand, in the production of aromatic polyester, a titanium compound catalyst may be used, and particularly in the production of polybutylene terephthalate, a titanium compound catalyst is usually used. However, the titanium compound catalyst causes deterioration of the polymer, and its use amount is suppressed as small as possible. Also, depending on the combination with the compound, it causes a coloring factor. For example, in Japanese Patent Application Laid-Open No. 57-90016, when an aliphatic dicarboxylic acid component such as adipic acid is copolymerized in the presence of a titanium compound, the obtained polymer is significantly colored. Is disclosed. This coloring is presumed to be due to the interaction between the titanium compound and the aliphatic dicarboxylic acid, unlike the polymer deterioration.

Several proposals have been made for this improvement. For example, in Japanese Patent Publication No. 8-80932, terephthalic acid or a derivative thereof, adipic acid or a derivative thereof and 1,4-butanediol are esterified or transesterified in the presence of a titanium compound, and the resulting reaction product is obtained. Discloses a method for producing an adipic acid copolymerized aromatic polyester, which is subjected to a polycondensation reaction in the presence of a titanium compound and a pentavalent phosphorus compound. Also, Japanese Patent Application Laid-Open No. 8-169945
In the publication, a polymerization method of polybutylene terephthalate in which an organic or inorganic calcium salt compound is added in a polymerization reaction of polybutylene terephthalate using an organic titanium compound as a catalyst is disclosed.

Although these coloring prevention techniques exhibit some effect in terms of prevention of coloring, the present inventors have studied, but as a modification technique, in particular, as a modification technique of the polyester film for laminating and forming a metal plate, other techniques have been proposed. When polymer blending with the above-mentioned aromatic polyester is carried out, the copolymerized aromatic polyester subjected to the above-mentioned coloring prevention technique is inferior in compatibility with other aromatic polyesters, so that sufficient required properties cannot be obtained.

[0011]

An object of the present invention is to provide an aliphatic saturated dicarboxylic acid copolymer-based aromatic polyester containing a specific amount of a titanium compound, which has a high compatibility with other aromatic polyesters. Polyester for metal plate lamination processing that has improved the impact resistance and moldability after can-making while maintaining the excellent fragrance retention, heat resistance, and retort resistance of the conventional polyester film. An object of the present invention is to provide a copolymerized aromatic polyester useful for producing a film.

Another object of the present invention is to further improve the impact resistance and moldability after can production while maintaining the excellent fragrance retention, heat resistance and retort resistance of the conventional polyester film. To provide a laminated (laminated) polyester film for metal plate lamination processing.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
According to the present invention, (1) an aliphatic saturated dicarboxylic acid having 4 to 12 carbon atoms is contained as a copolymer component, and a titanium compound dissolved in a polymer is contained in an amount of 30 to 200 ppm as titanium metal. (Polymerized aromatic polyester (I)).

(2) A polyester film for laminating and forming a metal plate, comprising the copolymerized aromatic polyester (I) as one of the constituent components of the film.

Is achieved by:

The copolymerized aromatic polyester (I) in the present invention is a copolymerized aromatic polyester in which the copolymerization component is an aliphatic saturated dicarboxylic acid having 4 to 12 carbon atoms, and the aromatic dicarboxylic acid constituting the main acid component Examples of the acid include terephthalic acid, isophthalic acid, phthalic acid, 2,6-
Naphthalenedicarboxylic acid and the like are preferred, and terephthalic acid is particularly preferred. Glycols constituting the main diol component include, for example, those having 2 to 1 carbon atoms.
0 alkylene glycols (eg, ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, etc.) and alicyclic glycols (eg, 1,4-cyclohexanedimethanol, etc.), among which tetramethylene glycol is Particularly preferred. Examples of the aliphatic saturated dicarboxylic acid having 4 to 12 carbon atoms include succinic acid, glutanic acid, adipic acid, pimelic acid, suberic acid, sebacic acid, and decanedicarboxylic acid. Those having 4 to 8 (adipic acid, pimelic acid, suberic acid, sebacic acid and the like), particularly adipic acid, are preferred.

The copolymerization ratio of the aliphatic saturated dicarboxylic acid component is preferably from 3 to 45 mol%, and more preferably from 3 to 45 mol%, based on all dicarboxylic acids constituting the copolymerized aromatic polyester (I).
A range of 30 mol% is particularly preferred. When the copolymerization ratio is 3
If the amount is less than mol%, for example, when deep drawing and ironing is performed by laminating to a metal plate, the formability and impact resistance are insufficient, which is not preferable. On the other hand, if it exceeds 45 mol%, heat resistance is undesirably reduced.

The copolymerized aromatic polyester (I) in the present invention may be copolymerized with a small amount of another copolymer component as long as its characteristics are not impaired. Other copolymerizable components include aromatic dicarboxylic acids other than the main acid component (for example, terephthalic acid, isophthalic acid, phthalic acid, p-oxybenzoic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid) Alicyclic dicarboxylic acids (e.g., 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, etc.), aliphatic dicarboxylic acids other than the aliphatic saturated dicarboxylic acids (e.g., dimer acid, etc.), oxy Carboxylic acids (for example, p-oxybenzoic acid, etc.), alkylene glycols other than the main diol component (for example, ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, etc.) and alicyclic diols (for example, 1,4 -Cyclohexanedimethanol, etc.),
Branched alkylene glycol (for example, propylene glycol, HO—CH ₂ —C (R) ₂ —CH ₂ —OH (however,
R is an alkyl group having 1 to 4 carbon atoms, particularly preferably methyl), diethylene glycol (DEG), triethylene glycol (TEG), polyoxyalkylene glycol (for example, polyethylene glycol, polypropylene glycol, etc.). it can. One or more of these can be used.

Among the above-mentioned copolymerized aromatic polyesters (I), they have good compatibility when blended with other aromatic polyesters, and a single-layer film or a laminated film is bonded to a metal plate and deep-drawn. In particular, copolymerized polybutylene terephthalate containing adipic acid as a copolymer component is most preferable, since it is particularly excellent in performance such as moldability and impact resistance.

The copolymerized aromatic polyester (I) in the present invention must contain a titanium compound soluble in the polymer in an amount of 30 to 200 ppm as titanium metal. Here, the amount of titanium metal in the titanium compound dissolved in the polymer is determined by dissolving the sample polymer in a solvent (for example, a mixed solution of chloroform / hexafluoroisopropanol) and centrifuging the insoluble titanium compound (for example, titanium oxide particles). The supernatant was evaporated to obtain a dried polymer, and the amount of titanium metal was determined by IPC emission analysis of a solution obtained by wet decomposition of the polymer.
When the amount of the titanium compound is less than 30 ppm as titanium metal, the compatibility with other aromatic polyesters is poor, and when the film is laminated on a metal plate and deep-drawn and used,
In particular, when performing deep drawing at extremely high magnification, or when performing high-order post-processing, it is not possible to obtain sufficient moldability and impact resistance, causing cracks and film whitening during molding, which is not preferable. . On the other hand, when the content exceeds 200 ppm, the melting heat stability of the polymer itself is reduced, and the molecular weight during the forming process is greatly reduced. Therefore, when the film is bonded to a metal plate and deep drawn, the formability is rather reduced. , Causing a decrease in impact resistance, which is not preferable. The content of titanium metal is preferably 40 to 180 p
pm, more preferably 50 to 160 ppm.

The titanium compound added to the copolymerized aromatic polyester (I) is a polymer-soluble titanium compound. This is because the transesterification is promoted when melt-mixed with another polyester, and a useful film for laminating and processing a metal plate can be sold. This titanium compound may be used as a catalyst for esterification or transesterification in synthesizing a polyester, or may be used as a catalyst for polycondensation. Moreover, you may add directly to the single-screw or twin-screw extruder etc. to the polyester after superposition | polymerization. Among these, in order to obtain a stable quality, a method of adding as a polymerization catalyst in the production of polyester is preferable.

Examples of the titanium compound added to the copolymerized aromatic polyester (I) include organic titanates such as tetra-n-butyl titanate, tetra-n-propyl titanate, tetraisopropyl titanate, tetraethyl titanate, tetramethyl titanate and the like. Hydrolysates, titanium tetrachloride, hydrolysates of titanium sulfate, inorganic titanium compounds such as titanium zinc fluoride, potassium titanium fluoride, titanium cobalt fluoride, titanium acetate, titanium oxalate,
A titanium compound used as a catalyst in the production of a normal polyester such as potassium potassium oxalate may be mentioned, but tetra-n-butyl titanate is preferred. Two or more of these titanium compounds may be used in combination.

The copolymerized polyester (I) in the present invention
As described above, in the production thereof, it is preferable to use a titanium compound as the polycondensation catalyst, but another polycondensation catalyst may be used alone or in combination with a titanium compound. The type is not particularly limited, and examples thereof include an antimony compound, a germanium compound, a tin compound, a calcium compound, and a magnesium compound.

The copolymerized aromatic polyester (I) in the present invention can be produced by a conventional method. Typical methods include aromatic dicarboxylic acids or their ester-forming derivatives (e.g., lower alkyl esters, preferably dimethyl esters), glycols and 4-1 carbon atoms.
(2) an esterification or transesterification reaction of an aliphatic saturated dicarboxylic acid (2) or an ester-forming derivative thereof (alkyl ester having 1 to 10 carbon atoms, preferably dimethyl ester), followed by a polycondensation reaction of the resulting reaction product. No. Solid phase polymerization may be performed as a polycondensation reaction. As the solid phase polymerization, for example, a method in which a normal pressure fluidized bed or a reduced pressure fluidized bed fluidized with nitrogen is used, or a method using a rotary vacuum dryer is preferably used.

The copolymerized aromatic polyester (I) in the present invention contains 0.01 to 0.5% by weight of an antioxidant,
More preferably, the content is 0.02 to 0.4 wt%. If this antioxidant is less than 0.01% by weight, the thermal stability is extremely lowered, which is not preferable. Not preferred. Examples of the antioxidant include a radical trap type antioxidant such as hindered phenol, secondary aromatic amine, and hindered amine, phosphonite, trialkyl phosphite,
A peroxide decomposable antioxidant such as dilauryl dipropionate may be mentioned, and among them, hindered phenol is preferable. Particularly preferred hindered phenols include tetrakis [methylene (3,5-di-t-butyl-4).
-Hydroxyhydro-cinnamate)] methane.

The copolymerized aromatic polyester (I) in the present invention includes, for example, a heat stabilizer, a viscosity modifier, a plasticizer, a hue improver, a nucleating agent, an ultraviolet absorber, a pigment, and an improvement in winding property in a film production process. Additives such as lubricants can be added as necessary.

The molecular weight of the copolymerized aromatic polyester (I) of the present invention is 0.70 to 1.50, more preferably 0.80 to 1.50, in terms of intrinsic viscosity (orthochlorophenol, 35 ° C.).
1.10. If the limiting viscosity number exceeds this suitable range, during molding processing, shear heat is particularly large in the melt extrusion step of film formation, rather leading to a decrease in molecular weight,
This is not preferable because the heat resistance of the film decreases. Also,
If the thickness is less than the appropriate range, a sufficient strength cannot be obtained at the time of forming the film, which is not preferable.

When the copolymerized aromatic polyester (I) in the present invention is used as a material for a polyester film for laminating and forming a metal plate, such as by laminating a metal plate and performing deep drawing, the copolymerized aromatic polyester is used. Polyester (I) 5
Aromatic polyester other than the copolymerized aromatic polyester (I) having a melting point of 200 to 255 ° C. and a melting point of 200 to 255 ° C.
I) It is preferable to mix and use 95 to 40 wt%. 5 wt% of copolymerized aromatic polyester (I)
If the ratio is less than 95% by weight, the film is inferiorly formed when the film is deep drawn at a high magnification, and the workability is poor, and the film is cracked and the whitening phenomenon occurs. On the other hand, when the proportion of the copolymerized aromatic polyester (I) exceeds 60 wt% and the content of the other aromatic polyester (II) is less than 40 wt%, the heat embrittlement resistance decreases,
Not preferred.

The aromatic polyester (II) may be a polyester (homopolymer) comprising an aromatic dicarboxylic acid component and a diol component, or a copolymer obtained by copolymerizing a third component (copolymer component) in addition to these components.

As the aromatic dicarboxylic acid constituting the main acid component of the aromatic polyester (II), for example, terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid and the like are preferable. Is preferred. Examples of the glycol component constituting the main diol component include, for example, alkylene glycols having 2 to 10 carbon atoms (eg, ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, etc.), and among them, ethylene glycol is preferable. . As the third component (copolymerization component), for example, aromatic dicarboxylic acids other than the main dicarboxylic acid (eg, terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, etc.), Alicyclic dicarboxylic acid (eg, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, etc.), aliphatic dicarboxylic acid (eg, adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dimer acid, etc.) Oxycarboxylic acid (for example, p-oxybenzoic acid), alkylene glycol other than main alkylene glycol (for example, ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, etc.), branched alkylene glycol (for example, propylene glycol) _{Le, HO-CH 2 -C (R} ) 2 -CH 2 -OH ( Here, R
Is an alkyl group having 1 to 4 carbon atoms, particularly preferably methyl), diethylene glycol (DEG), triethylene glycol (TEG), alicyclic diol (for example,
Examples thereof include 1,4-cyclohexanedimethanol and the like, and polyoxyalkylene glycols (eg, polyethylene glycol and polypropylene glycol). One or more of these can be used.

Among these aromatic polyesters (II), the compatibility with the copolymerized polyester (I), and the moldability, retort resistance, heat resistance, etc. of the polyester film which can be laminated and formed on a metal plate. Thus, copolymerized polyethylene terephthalate is preferred, and isophthalic acid is preferred as a copolymerized component in terms of forming a well-balanced polyester film.

The proportion of the above-mentioned aromatic polyester copolymer component depends on the kind thereof, and is such that the melting point is in the range of 200 to 255 ° C., preferably 210 to 245 ° C. If the melting point is lower than 200 ° C., the heat resistance will be inferior, while if the melting point exceeds 255 ° C., the moldability will be significantly impaired.

Here, the melting point of the aromatic polyester was measured by using Du Pont Instruments 910.
A method of obtaining a melting peak at a heating rate of 20 ° C./min using DSC. The sample amount is about 20 mg.

Further, the molecular weight of the aromatic polyester (II) is preferably 0.52 to 1.50 in terms of intrinsic viscosity (orthochlorophenol, 35 ° C.), more preferably 0.57 to 1.00. Particularly preferably 0.60
0.80. If the limiting viscosity number is less than 0.52, the resulting film may not have sufficient elongation, resulting in insufficient molding workability and impact resistance. On the other hand, when the limiting viscosity number exceeds 1.50. Is preferable because the melt viscosity of the polyester is high, and the shear heat generation in the extruder during film formation is too large, so that the molecular weight of the obtained polyester is greatly reduced, and as a result, moldability and impact resistance are reduced. Absent.

The aromatic polyester (II) in the present invention
Can be manufactured by conventional methods. As a typical method, a dicarboxylic acid or an ester-forming derivative thereof and a glycol are esterified or transesterified, and
Next, a method of subjecting the obtained reaction product to a polycondensation reaction may be mentioned. The polycondensation reaction may include a solid phase polymerization.
As the solid phase polymerization reaction, for example, a method in which a normal pressure fluidized bed or a reduced pressure fluidized bed fluidized with nitrogen is used, or a method using a rotary vacuum dryer is preferably used.

As the polycondensation catalyst used in the production of the aromatic polyester (II), those known as polyester polycondensation catalysts can be used, and the type thereof is not particularly limited. , Germanium compounds, tin compounds, calcium compounds, magnesium compounds and the like. Among these, a titanium compound and a germanium compound are particularly preferable from the viewpoint of the fragrance retention of the film. Preferred examples of the titanium compound include tetrabutoxytitanate, titanium acetate and the like. Examples of the germanium compound include (a) amorphous germanium oxide, (b) fine crystalline germanium oxide, and (c) a solution in which germanium oxide is dissolved in glycol in the presence of an alkali metal or an alkaline earth metal or a compound thereof. And (d) a solution in which germanium oxide is dissolved in water.

The aromatic polyester (II) in the present invention
If necessary, additives such as a heat stabilizer, a viscosity modifier, a plasticizer, a hue improver, a nucleating agent, an ultraviolet absorber, a lubricant and a pigment may be added as necessary.

The polyester film for laminating and forming a metal plate obtained by melt-mixing the copolymerized aromatic polyester (I) and the aromatic polyester (II) in the above-mentioned amount ratio in the present invention is a single-layer film. Is also useful, the polyester layer (A) made of the molten mixture is combined with one component of the laminated film, particularly, having a melting point of 210-2.
Copolymerized aromatic polyester (II) other than copolymerized aromatic polyester (I) having 45 ° C. and glass transition point of 60 ° C. or higher
Lamination with the polyester layer (B) composed of (I) is more preferable from the viewpoint of improving impact resistance, moldability, and flavor. The components constituting the copolymerized aromatic polyester (III) are the same as those described for the aromatic polyester (II).

The copolymerization ratio of the copolymerized aromatic polyester (III) depends on its type, but its melting point is 210 ° C.
245 ° C. If the melting point is lower than 210 ° C., the heat resistance will be poor. On the other hand, if the melting point exceeds 245 ° C., the moldability will be impaired, which is not preferable.

In the present invention, the copolymerized aromatic polyester (III) has a glass transition temperature of 60 ° C. or higher, preferably 70 ° C. or higher. If the glass transition temperature is lower than 60 ° C., it is difficult to obtain satisfactory scent retention. Therefore, it is preferable to determine the type and amount of the copolymer component in the copolymerized aromatic polyester (III) in consideration of both the melting point and the glass transition temperature of the polymer.

Here, the copolymerized aromatic polyester (II
The measurement of the melting point and the glass transition temperature of I) was carried out in the same manner as in the above-mentioned aromatic polyester (II) by Du Pont Instrument.
ents 910 DSC, a method of obtaining a melting peak and a glass transition point peak at a heating rate of 20 ° C./min. The sample amount is about 20 mg.

Further, copolymerized aromatic polyester (III)
(Orthochlorophenol, 35 ° C.) is preferably in the same range as the intrinsic viscosity of the aromatic polyester (II).

The method for producing the copolymerized aromatic polyester (III) and the polycondensation catalyst used in the present invention are the same as those described for the aromatic polyester (II). Further, as the polycondensation catalyst, a titanium compound and a germanium compound are particularly preferable from the viewpoint of fragrance retention. Preferred examples of the titanium compound include tetrabutoxytitanate, titanium acetate and the like. Examples of the germanium compound include (a) amorphous germanium oxide,
(B) fine crystalline germanium oxide, (iii) a solution of germanium oxide dissolved in glycol in the presence of an alkali metal or an alkaline earth metal or a compound thereof,
(D) A solution obtained by dissolving germanium oxide in water is preferred.

The copolymerized aromatic polyester (III) may optionally contain additives such as a heat stabilizer, a viscosity modifier, a plasticizer, a hue improver, a nucleating agent, an ultraviolet absorber, a pigment and a lubricant. It may be added.

The polyester film of the present invention preferably contains a lubricant at a ratio of 1% by weight or less in order to improve the winding property (handleability, longness) in the film production process.

This lubricant is preferably contained in at least one of the copolymerized aromatic polyester (I) and the aromatic polyester (II). Similarly, the copolymerized aromatic polyester (III) forming the polyester layer (B) may or may not contain a lubricant, but the former is preferred.

The lubricant may be inorganic or organic, but inorganic is preferred. Examples of the inorganic lubricant include silica, alumina, titanium dioxide, calcium carbonate, barium sulfate, and the like, and examples of the organic lubricant include crosslinked polystyrene and crosslinked silicone resin particles. In any case, the average particle diameter is preferably 2.5 μm or less, and more preferably 0.05 to 2.2 μm. When the average particle size of the lubricant exceeds 2.5 μm, coarse lubricant particles (for example, particles of 10 μm or more) serve as starting points in portions deformed by can-making such as deep drawing and ironing, and pinholes are generated. In some cases, it is not preferable because it causes breakage. Particularly preferred lubricants in terms of pinhole resistance are monodispersed spherical lubricants having an average particle diameter of 2.5 μm or less and a particle diameter ratio (major axis / short diameter) of 1.0 to 1.2. . As such a lubricant,
Spherical silica, spherical zirconium oxide, and spherical crosslinked silicone resin particles can be exemplified.

The content of the lubricant is 0.005 to 5% by weight.
However, it may be determined according to the winding property in the film manufacturing process. In general, large particles are small,
It is preferable to include a large amount of small ones. For example,
0.05 in the case of monodisperse silica having an average particle size of 2.0 μm.
It is preferable to add about 0.4 wt% for titanium dioxide having about wt% and an average particle diameter of 0.3 μm. Further, the content of the fine particles can be intentionally increased to make the film opaque. For example, a white film can be obtained by adding 5 to 40 wt%, preferably 10 to 20 wt% of titanium dioxide.

The lubricant is not limited to the above-mentioned externally added particles. For example, internal precipitated particles obtained by depositing a part or all of the catalyst used in the production of polyester in the reaction step can be used. It is also possible to use externally added particles and internally precipitated particles in combination.

The polyester film for laminating and forming a metal plate of the present invention can be formed by any conventionally known method. For example, copolymerized aromatic polyester (II
When producing a laminated film in which a polyester layer (B) composed of I) and a polyester layer (A) obtained by melt-mixing a predetermined amount of a copolymerized aromatic polyester (I) and an aromatic polyester (II) are laminated, The copolymerized aromatic polyester (III) forming the polyester layer (B) and the composition comprising the copolymerized aromatic polyester (I) and the aromatic polyester (II) forming the polyester layer (A) are separately dissolved. Then, laminated in a die and co-extruded, or co-extruded and laminated and fused before solidification, then biaxially stretched, heat-set, or separately melt and extrude the polymer forming each layer. Into a film, in an unstretched state or after stretching,
Although both can be manufactured by a method of laminating and fusing them, the former is preferable. The stretched film is usually heat-set, but in this case, the heat-setting temperature is preferably selected from the range of 150 to 200 ° C, more preferably 160 to 200 ° C.

The polyester film (biaxially stretched film) of the present invention preferably satisfies the following requirements (1) and (2).

(1) The refractive index in the thickness direction of the film is 1.
505 or more and 1.550 or less, more than 1.510 and
It is preferably 540 or less. If the refractive index is too low, the molding processability becomes insufficient, while if it is too high (in the case of an excessively low orientation), the structure becomes almost amorphous, so that the heat resistance tends to be insufficient.

(2) The refractive index in the plane direction of the film is preferably 1.610 to 1.660 in all directions. The refractive index in the film surface direction is preferably as uniform as possible in all directions. If the value of the refractive index is out of the above range, the anisotropy of the film becomes remarkable, so that the moldability tends to deteriorate.

The refractive index of the film was measured by attaching a polarizing plate analyzer to the eyepiece side of the Abbe refractometer,
Using the line D, the refractive index in the thickness direction and the refractive index in the plane orientation are measured. At that time, the mounting liquid used methylene iodide,
The measurement temperature is 25 ° C. Alternatively, the measurement may be performed by another equivalent measurement method.

The polyester film (A) having the copolymerized aromatic polyester (I) becomes an adhesive layer when it is bonded to a metal plate, and is disposed on the metal plate side. Is preferred. When the polyester layer (B) is disposed on the metal plate side as an adhesive layer, the adhesion to the metal plate is poor, which is not preferable.

The thickness of the polyester film of the present invention is
Preferably 6-75 μm, more preferably 10-75 μm
m, particularly preferably 15 to 50 μm. If the thickness is too thin, breakage or the like is likely to occur during deep drawing and ironing, while if it is too thick, it is excessive quality and uneconomical.

In the case of a laminated film, the thickness of the polyester layer (A) (adhesive layer) varies depending on the roughness of the metal plate, but in the case of a normal smooth surface, the thickness is 2 μm or more to obtain a stable adhesive force. It is enough. In particular, when emphasis is placed on retort properties and rust prevention properties, the thickness is preferably 12 μm or more. From these points, the polyester layer (A)
The thickness T _A of the ratio between the thickness T _B of the polyester layer _{(B) (T B / T} A) is preferably from 0.02 to 0.67, more preferably 0.04 to 0.43, particularly preferably Is 0.
05 to 0.25. Specifically, for example, when the thickness is 25
In the case of a laminated film of μm, the thickness of the polyester layer (A) (adhesive layer) is 15 to 24.5 μm, preferably 17.
The range is preferably 5 to 24 μm, more preferably 20 to 24 μm.

As a metal plate for cans to which the polyester film for metal plate lamination processing of the present invention is bonded, a plate of tin, tin-free steel, aluminum or the like is suitable. The bonding of the polyester film to the metal plate can be performed, for example, by the following method.

After the metal plate is heated to a temperature higher than the melting point of the film and the films are bonded together, the film is cooled, and the surface layer (thin layer) of the film in contact with the metal plate is made amorphous and adhered.

An adhesive layer is primer-coated on the film in advance, and this surface is bonded to a metal plate. As the adhesive layer, a known resin adhesive, for example, an epoxy adhesive, an epoxy-ester adhesive, an alkyd adhesive, or the like can be used.

In the case of a laminated film, the layers between the polyester layer (A) and the polyester layer (B) are usually in direct contact with each other, but if necessary, the polyester layer (A) and the polyester layer Another additional layer may be laminated between (B), for example, another thin adhesive layer, anchor coat layer, discharge treatment layer, etc. are interposed between the polyester layer (A) and the polyester layer (B). You may. If necessary, another additional layer may be laminated on the surface opposite to the adhesive surface between the polyester layer (A) and the polyester layer (B).

The polyester film for metal plate lamination molding of the present invention is particularly excellent in deep drawing and ironing processability. Therefore, after laminating with a metal plate, the ratio of the body diameter to the height of the can is 1: 2. As described above, the present invention is particularly useful for the production of a metal can with a large deep drawing ratio of 1: 2.3 or more, especially 1: 2.6 or more.

[0063]

The present invention will be further described with reference to the following examples.
The properties in the examples were measured by the following methods.

(1) Amount of titanium metal The copolymerized aromatic polyester (I) was dissolved in a mixed solution of chloroform / hexafluoroisopropanol (1/1),
The solution is centrifuged at 100,000 G to remove the polymer-insoluble titanium compound. Evaporate the remaining supernatant solution to obtain a dry polymer. This polymer was sampled, and the solution obtained by wet decomposition with a mixed solution of sulfuric acid / nitric acid (1/1) was subjected to IPC (IPC manufactured by Rigaku / Jobin-Yvon).
The amount of titanium metal contained in the polymer is quantified by an emission spectrometer) analysis.

(2) Laminability After laminating the film to a tin-free steel plate heated to a temperature higher than the melting point of polyester, the film is cooled to obtain a coated steel plate. The lamination property of this coated steel sheet is determined according to the following criteria. (A) Criteria for determining bubbles and wrinkles ○: No bubbles and wrinkles are observed. C: Bubbles and wrinkles are observed at two or three places per 10 m in length. ×: Many bubbles and wrinkles are observed. (B) Criteria for determining heat shrinkage 収縮: Shrinkage is less than 2%. Δ: Shrinkage rate is 2% or more and less than 5%. X: Shrinkage rate is 5% or more.

(3) Deep drawing processability-1 A sideless seamless container (hereinafter abbreviated as can) having a diameter of 50 mm and a height of 150 mm is formed from a taint-free steel plate laminated with a film using a die and a punch. The following observations and tests are performed on this can, and each can is evaluated according to the following criteria. ：: No abnormality in the film, and no whitening or breakage was observed in the processed film. Δ: Whitening is observed at the top of the film can. X: Film breakage is observed in a part of the film.

(4) Deep drawing processability-2 ◎: Processed without any abnormality, rust prevention test on film surface in can (1% NaCl water was put in the can, electrodes were inserted, and the can body was used as an anode. The current value when a voltage of 6 V is applied is measured.
In the following, abbreviated as ERV test), 0.005 mA or less is shown. ：: In the ERV test, a value of 0.005 to 0.05 mA is shown. Δ: A value of 0.05 to 0.1 mA is shown for the ERV test. X: A value of 0.1 mA or more is shown for the ERV test,
When the energized portion is observed under magnification, cracks are observed.

(5) Adhesiveness The cans having good deep drawing properties are filled with water and subjected to a retort treatment at 120 ° C. for 90 minutes with a steam sterilizer, and then stored at 50 ° C. for 3 months. A cross cut is made on the obtained can, and the adhesion state of the film is observed. ：: Strongly adhered and did not peel off even when a cross cut was inserted. Δ: Adhesion strength was slightly reduced by cross cut. X: The film peels when a cross cut is made.

(6) Rust Prevention A 5% acetic acid aqueous solution is fully poured into cans having good deep drawability, and kept at 50 ° C. for 2 weeks. In each test, the state of rust on the metal plate was visually observed and evaluated for each of 10 cans. ：: No rust was observed for all 10 pieces. Δ: About 1 to 5, rust is observed. ×: Rust is observed for 6 or more pieces.

(7) Impact resistance For cans with good deep drawing, pour water thoroughly, cool to 10 ° C., and weigh 10 pieces for each test from a height of 2 m from vinyl chloride resin (hereinafter abbreviated as PVC). After dropping it on the tile floor, and holding it for one month, it is evaluated by an ERV test in the can. ：: 0.1 mA or less for all 10 samples. C: 0.1 mA or more for 1 to 5 pieces. ×: 0.1 mA or more for 6 or more pieces, or cracking of the film was already observed after dropping.

(8) Heat-resistant embrittlement
After heating and holding, the impact resistance evaluation described in (7) is performed. ：: 0.1 mA or less for all 10 samples. C: 0.1 mA or more for 1 to 5 pieces. ×: 0.1 mA or more for 6 pieces, or 2
After heating at 10 ° C. for 5 minutes, cracking of the film has already been observed.

(9) Retort resistance The cans having good deep drawing properties are filled with water and subjected to a retort treatment at 120 ° C. for 90 minutes at a steam sterilizer, and then stored at 50 ° C. for 30 days. . After dropping 10 cans for each test from a height of 50 cm on a PVC tile floor, ERV in the cans is performed. ：: 0.1 mA or less for all 10 samples. C: 0.1 mA or more for 1 to 5 pieces. C: The film is 0.1 mA or more for 6 or more pieces, or cracks of the film are already observed after dropping.

(10) Flavor Retention A cut sheet of 21 cm × 30 cm was obtained from the polyester film, and this sample film was immersed in 300 ml of ion-exchanged water and stored at normal temperature (20 ° C.) for one month. The immersion liquid is used for tasting by 30 panelists, compared with ion-exchanged water for comparison, and evaluated according to the following criteria. ◎: 4 or less out of 30 persons judged that the taste was inferior to that of the comparative solution. ：: 5 to 6 out of 30 persons judge that the taste was inferior to that of the comparative solution. Δ: 7 to 9 out of 30 persons judged that the taste was inferior to that of the comparative solution. ×: 10 or more out of 30 persons judged that the taste was inferior to that of the comparative solution.

Examples 1 to 5 and Comparative Examples 1 to 4 Tetrabutoxytitanate was used as a titanium compound as a catalyst and Irganox 1010 was used as an antioxidant so that the amount of titanium metal was as shown in Table 1. 0.2 wt
% And a copolymerized aromatic polyester (I) having a limiting viscosity number of 1.00 was prepared by a polycondensation method. This copolymerized aromatic polyester (I) and the separately produced aromatic polyester (II) (Table 1)
Containing 0.3% by weight of spherical silica having a composition and a melting point shown in Table 1 and having an intrinsic viscosity of 0.70 and an average particle diameter of 1.0 μm)
A copolymerized aromatic polyester (III) (intrinsic viscosity) having the composition, melting point, and glass transition temperature shown in Table 1 separately prepared so that the polyester composition blended with the above becomes a polyester layer (A) (adhesive layer). After drying and melting each separately by a conventional method so that the (number 0.70) becomes the polyester layer (B), they are co-extruded from dies adjacent to each other, laminated, fused, quenched and solidified. A stretched laminated film was prepared. Next, the unstretched laminated film was longitudinally stretched at 100 ° C. to 3.0 times, and then stretched in the transverse direction at a magnification of 3.0 times while changing the temperature and the amount of hot air blown. After heat setting, a biaxially stretched laminated polyester film was obtained.

Comparative Example 5 Only the copolymerized aromatic polyester (III) of Example 1 was melt-extruded and the film thickness was 25 μm.
A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that a single-layer film was used.

Example 6 Only the same composition as the polyester layer (A) of Example 1 was melt-extruded and the film thickness was 25
A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that a single-layer film of μm was used.

[0077]

[Table 1]

In Table 1, IA is isophthalic acid, AA
Represents adipic acid, SA represents sebacic acid, PET represents polyethylene terephthalate, and PBT represents polybutylene terephthalate. Further, Tg indicates a glass transition temperature point, and Tm indicates a melting point.

The above-obtained 11 types of biaxially stretched films were bonded to a tin-free steel plate heated to a temperature not lower than the melting point of polyester, and then cooled to obtain a coated steel plate. Using a punch, a seamless side can was formed.

Table 2 shows the laminating property, moldability, adhesive property, and other characteristics of the can.

[0081]

[Table 2]

In Table 2, "-" indicates that no evaluation was made.

As is clear from the results in Table 2, in the can using the polyester film having the copolymerized aromatic polyester (I) of the present invention, the laminability, heat embrittlement resistance, retort resistance, rust resistance, In addition to good scent retention, it was particularly excellent in deep drawing processability and impact resistance.

[0084]

EFFECT OF THE INVENTION The polyester film for metal plate laminating and processing comprising the copolymerized aromatic polyester (I) of the present invention has good heat resistance, retort resistance, rust prevention, adhesiveness and fragrance retention. In addition, the moldability and impact resistance are extremely excellent. Therefore, it is suitable for deep-drawn metal cans, especially for beverage cans and food cans.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 67/02 C08L 67/02

Claims (12)

[Claims] 1. A copolymer having an aliphatic saturated dicarboxylic acid having 4 to 12 carbon atoms as a copolymer component and containing a titanium compound dissolved in the polymer in an amount of 30 to 200 ppm as titanium metal. Aromatic polyester. 2. An aliphatic saturated dicarboxylic acid having 6 to 1 carbon atoms.
The copolymerized aromatic polyester according to claim 1, which is an aliphatic saturated dicarboxylic acid of 0. 3. The copolymerized aromatic polyester according to claim 1, wherein the aliphatic saturated dicarboxylic acid is adipic acid. 4. The copolymerized aromatic polyester according to claim 1, wherein the copolymerization ratio of the aliphatic saturated dicarboxylic acid is 3 to 45 mol% based on all dicarboxylic acids. 5. The copolymerized aromatic polyester according to claim 4, wherein the copolymerization ratio of the aliphatic saturated dicarboxylic acid is 10 to 30 mol% based on all dicarboxylic acids. 6. The copolymerized aromatic polyester film according to claim 1, wherein the titanium compound dissolved in the polymer is contained in an amount of 50 to 160 ppm as titanium metal. 7. The copolymerized aromatic polyester according to claim 1, wherein the copolymerized aromatic polyester is a copolymerized polybutylene terephthalate. 8. The copolymerized aromatic polyester according to claim 1, wherein the intrinsic viscosity of the copolymerized aromatic polyester is 0.70 to 1.50. 9. The copolymerized aromatic polyester according to claim 1, which contains 0.01 to 0.5% by weight of an antioxidant. 10. The copolymerized aromatic polyester (I) according to claim 1, having a melting point of 200 to 255 ° C.
A polyester film for metal plate lamination molding, comprising a molten mixture of 95 to 40% by weight of an aromatic polyester (II) other than the copolymerized aromatic polyester (I). 11. A polyester layer (A) comprising the molten mixture according to claim 10 and a copolymer other than the copolymerized aromatic polyester according to claim 1 having a melting point of 210 ° C. to 245 ° C. and a glass transition temperature of 60 ° C. or higher. Polymerized aromatic polyester (II
A laminated polyester film for laminating a metal plate, which is a laminated film with a polyester layer (B) comprising I). 12. The laminated polyester film according to claim 11, wherein the polyester layer (A) serves as an adhesive layer to the metal plate.