JPH08269215A - Polyester film for lamination with metallic sheet - Google Patents

Abstract

PURPOSE: To obtain a polyester film for lamination with a metallic sheet, being excellent in sliperiness, heat resistance, impact resistance and flavor retention and desirably used for a metallic can produced by forming. CONSTITUTION: A polyester film for lamination with a metallic sheet, containing particles the degree of deformation D/d of which is 1.1 or above (wherein D is the maximum length of a particle, and d is the minimum length of the particle). It is desirable that the particles are agglomerated inorganic particles of wet-process or dry-process silica or alumina, and the agglomearated particles are each composed of 100nm or smaller primary particles. It is desirable that the content of the particles is 0.005-5wt.%. The particles having a degree of deformation of 1.1 or above may be used in conjunction with particles having a degree of deformation of below 1.1. It is particularly desirable that the polyester is polyethylene terephthalate or polyethylene naphthalate. Further, a polyester containing 1.5wt.% or below diethylene glycol and 1-500ppm of Ge, Sb or Ti is desirable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester and a film for laminating metal plates. More specifically, the present invention relates to a polyester film for laminating metal plates, which is excellent in flavor, heat resistance, impact resistance, particularly impact resistance and is suitable for metal cans such as beverage cans and food cans produced by molding.

[0002]

2. Description of the Related Art Conventionally, for the purpose of preventing corrosion, the inner and outer surfaces of a metal can are coated with various thermosetting resins such as epoxy type and phenol type which are dissolved or dispersed in a solvent to coat the metal surface. Coating 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 for solving these problems, a method of laminating a polyester film 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 the metal can, is carried out. . When laminating a polyester film or forming a laminated metal plate of the film to produce a metal can,
The polyester film is required to have the following properties. (1) Excellent adhesion to a metal plate. (2) The laminated polyester film is not crystallized or deteriorated by heating such as drying after can making, printing baking, retort sterilization treatment, etc., and peeling, shrinkage, cracks, pinholes, etc. of the film do not occur. (3) The polyester film should not be peeled off or cracked by the impact on the metal can. (4) The scent component of the contents of the can is adsorbed on the polyester film, and the flavor of the contents is not impaired by the elution component and odor of the polyester film (hereinafter referred to as flavor property).

Many proposals have been made to solve these requirements. For example, JP-A-1-22530 discloses a polyester film having a specific density and plane orientation coefficient, and JP-A-2-57339 discloses. A copolyester film or the like having a specific crystallinity is disclosed. For example, in Japanese Patent Application Laid-Open No. 2-305827, slip properties are improved by containing a lubricant having a specific size, and pinholes are generated, squeezed, and folded. Bend formability has been improved.
However, these proposals are not able to comprehensively satisfy the various required characteristics as described above, and it cannot be said that they are at a level that can sufficiently satisfy impact resistance in particular.

[0005]

An object of the present invention is to eliminate the above-mentioned problems of the prior art, and is excellent in slipperiness, heat resistance, impact resistance, flavor property, particularly impact resistance, and molding process. It is intended to provide a polyester film for laminating a metal plate, which is suitable for a metal can manufactured by.

[0006]

The object of the present invention described above is such that the deformation degree (ratio of the maximum length D to the minimum length d of particles) in the film defined by the following formula (1) is 1. 1
This can be achieved by a polyester film for laminating metal plates, which contains the above particles. Deformation degree = D / d (1)

A feature of the present invention is that the film does not deteriorate in slipperiness, handleability, laminating workability on a metal plate and moldability of a metal plate, and cracks and pinholes are generated in the film in these steps. There is no such thing. Furthermore, when a metal can is used, particles that act as a lubricant to improve film slipperiness and handleability in order to suppress film peeling, cracks, and pinholes caused by impact on the metal can are used in the film forming process of the film. ,
The point is that the metal plate is appropriately deformed in the process of laminating it on a metal plate or forming and processing a metal plate.

The film of the present invention contains particles having a degree of deformation of 1.1 or more in the film. The degree of deformation of the particles is preferably 1.5 or more, more preferably 3 or more, and further preferably 5 or more. If the degree of deformation of the particles in the film is less than 1.1, voids occur around the particles or particles near the surface of the film fall off, resulting in cracks or pinholes in the film, resulting in poor impact resistance.

The degree of deformation of the particles of the present invention is represented by the ratio of the maximum length to the minimum length of the particles observed in the film as defined by the equation (1), and is determined by the method defined later. . Here, the maximum length of the particles is the distance between the parallel lines of the longest distance in contact with the contour, considering individual particles or particles formed at intervals smaller than the primary particle diameter as one particle, and the minimum length is the longest. It is the particle length in the direction perpendicular to the maximum length at the position of 1/2 of the distance.

The deformation of the particles is not particularly limited regardless of the type, size and shape of the particles. For example, during the production of particles, polyester film formation, stretching, film laminating to a metal plate, particle division, fragmentation, crushing, deformation due to unraveling, or bending or bending in the steps of forming a laminated metal plate, etc. Deformation etc. are mentioned. The shape of the deformed particles includes an elliptical shape, a spindle shape, a rod shape, a needle shape, a fibrous shape, a plate shape, and the like, and each particle may have such a shape or may be formed by an aggregate. good.

The polyester film containing particles having a degree of deformation of 1.1 or more may be a film formed by molding polyester containing deformed particles, which is deformed in the step of molding the polyester containing particles into a film. It may be a film containing particles, or a film containing particles deformed in the step of laminating a film containing particles on a metal plate or in the step of forming a laminated metal plate into a metal can. good.

The degree of deformation of the particles of the present invention is such that the film produced from polyester containing the particles, the film peeled from the metal plate laminated with the film, the film peeled from the metal can molded from the laminated metal plate. It can be determined by observing the particles contained therein.

The particles of the present invention are not particularly limited, but various inorganic particles and organic particles can be appropriately selected and used. For example, as the inorganic particles, wet method and dry method silica, porous silica, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, zirconia, mica, kaolin, clay, spinel, etc., and as organic particles or organic polymer particles, Vinyl particles such as polystyrene particles, crosslinked polystyrene particles, styrene / acrylic crosslinked particles, acrylic crosslinked particles, styrene / methacrylic crosslinked particles, methacrylic crosslinked particles, silicone, benzoguanamine / formaldehyde, polytetrafluoroethylene, polyphenyl Examples thereof include particles having an ester or a phenol resin as a constituent component. Among them, from the viewpoint of particle deformation and film slipperiness in various molding processes, wet method and dry method silica, agglomerated inorganic particles such as alumina, or crosslinked polystyrene particles, vinyl particles such as styrene / acrylic crosslinked particles, Organic particles having a silicone resin as a constituent component are preferable, and wet inorganic particles and dry inorganic particles such as silica and alumina are preferable from the viewpoint of improving the slipperiness of the film, the moldability of metal cans and the impact resistance. . The agglomerated particles mentioned here are particles in which at least 50% or more of the particles observed in polyester are formed of two or more primary particles. The particle size of these inorganic particles and organic particles is not particularly limited, but the deformation and film slipperiness of the particles in various molding processes,
From the viewpoint of moldability and impact resistance of the metal can, the average particle size is preferably in the range of 0.005 to 5 μm. More preferably 0.01 to 4 μm, still more preferably 0.05 to
It is in the range of 3 μm. In addition, especially the agglomerated particles are 100 nm
It is preferably formed from the following primary particles. It is more preferably 70 nm or less, and further preferably 5
It is 0 nm or less. If the primary particle size exceeds 100 nm, the film may have good slip properties and the metal can has good moldability, but the impact resistance may be poor. Further, these particles may have a single structure or may be composed of two or more kinds of components or structures, and have been subjected to dispersion processing, surface modification, etc. with an inorganic, organic, polymeric modifier or the like. Is also good. Two or more kinds of these particles may be used in combination.

The content of the particles of the present invention is not particularly limited, but is preferably 0.005 to 5% by weight, more preferably 0, from the viewpoint of the slipperiness of the film and the moldability of the metal can. 0.03 to 2% by weight, and more preferably 0.02 to 2% by weight. The content of particles is 0.005
If it is less than wt%, the slipperiness of the film and the moldability of the metal can may be deteriorated. In addition, the content of particles is 5% by weight
If it exceeds the range, the film may be broken or particles may be dropped due to the formation of coarse particles, and the impact resistance and the flavor property may be deteriorated.

Further, according to the present invention, in addition to containing particles having a degree of deformation of 1.1 or more, particles having a degree of deformation of less than 1.1 are used in combination, whereby the slipperiness of a film and the molding of a metal can are achieved. Workability may be improved. Such particles are not particularly limited, but examples of the inorganic particles include colloidal silica, porous silica, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, zirconia, mica, kaolin, clay and spinel. As the organic particles or organic polymer particles, polystyrene particles, cross-linked polystyrene particles, styrene-acrylic cross-linked particles, acrylic cross-linked particles, styrene-methacrylic cross-linked particles, methacrylic cross-linked particles, and other vinyl-based particles, silicone, benzoguanamine Particles containing formaldehyde, polytetrafluoroethylene, polyphenyl ester, phenol resin, etc. as constituent components can be mentioned. Of these, inorganic particles and / or organic particles having a degree of deformation of less than 1.1 are preferable from the viewpoints of the slipperiness and surface flatness of the film. The particle size and content of the particles are not particularly limited, but the average particle size is 0.01 to 5 μm.
Is preferable, and a range of 0.05 to 3 μm is more preferable. The content is preferably 0.001 to 3% by weight, more preferably 0.005 to 2% by weight.

The method of incorporating the particles of the present invention into a film is not particularly limited. For example, a method of molding the particle-containing polyester obtained at any stage of the polyester production process into a film, the particles Of polyester or polyester containing a large amount of the above and then blending the polyester and polyester not containing particles to form a film, or a method of dry blending polyester and particles and forming into a film, etc. Can be mentioned.

The polyester in the present invention means a polyester composed of an aromatic dicarboxylic acid component and a glycol component, and the aromatic dicarboxylic acid component constituting the polyester, a dicarboxylic acid component other than the glycol component and / or a glycol component are copolymerized. It is preferable to use the above polyester. As a polyester copolymerized with a dicarboxylic acid component and / or a glycol component, conventionally known polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polycyclohexylene dimethylene terephthalate,
Examples thereof include polyethylene naphthalate, and among these, polyethylene terephthalate and polyethylene naphthalate are particularly preferable in terms of heat resistance, impact resistance, and flavor property.

Examples of the dicarboxylic acid component copolymerizable with the above-mentioned polyester include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyletherdicarboxylic acid. Aliphatic dicarboxylic acids such as aromatic dicarboxylic acids such as 5-sulfoisophthalic acid and phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid and fumaric acid, and cyclohexanedicarboxylic acid Group dicarboxylic acids and the like can be mentioned. Of these dicarboxylic acid components, isophthalic acid and naphthalenedicarboxylic acid are particularly preferable from the viewpoint of heat resistance, impact resistance and flavor. These dicarboxylic acid components may be alkyl esters or the like.

The glycol component copolymerizable with the above-mentioned polyester is, for example, ethylene glycol,
Aliphatic glycols such as triethylene glycol, polyethylene glycol, polytetramethylene glycol, propanediol, butanediol, pentanediol, hexanediol and neopentyl glycol, aromatic glycols such as bisphenol A and bisphenol S, and fats such as cyclohexanedimethanol. Examples thereof include cyclic glycols, and among these glycol components, ethylene glycol, neopentyl glycol, cyclohexanedimethanol and diethylene glycol are particularly preferable from the viewpoint of impact resistance and flavor.

The above dicarboxylic acid component and glycol component may be used alone or in combination of two or more. These copolymerization components are preferably copolymerized in an amount of 1 to 30 mol% with respect to the total acid components constituting the copolyester from the viewpoint of adhesiveness to the metal plate, and more preferably 5 to 20.
mol%, and more preferably 7 to 15 mol%.
When the copolymerization amount is less than 1 mol%, the adhesion to the metal plate is poor, and the film may be peeled off or the impact resistance may be poor due to accelerated crystallization of the film in the process of manufacturing the metal can. is there. On the other hand, if it exceeds 30 mol%, the melting point tends to be low and the heat resistance may be poor.

Further, as long as the effects of the present invention are not impaired, polyfunctional compounds such as trimellitic acid, trimesic acid, pentaerythritol, trimethylolpropane and glycerin are added to polyester for the purpose of improving the moldability and handling of the film. An oxycarboxylic acid such as p-oxybenzoic acid may be copolymerized.

The melting point of the copolyester of the present invention is preferably 150 ° C. or higher from the viewpoint of showing heat resistance that can withstand heat treatment such as drying in a can making process and printing / baking, and the copolyester has an appropriate crystallinity. In order to obtain a film excellent in keeping and impact resistance, the temperature is preferably 250 ° C. or lower. A more preferable melting point range is 170 ° C to 240 ° C, and a still more preferable range is 180 ° C to 230 ° C. If the melting point of the copolyester is less than 150 ° C., the polymer may deteriorate due to heat such as drying in the can making process, and cracks and pinholes may occur, resulting in poor impact resistance and flavor. As described above, the copolyester having such a melting point is obtained by adding the aromatic dicarboxylic acid component and the glycol component to the polyester, and the aromatic dicarboxylic acid component constituting the polyester, the dicarboxylic acid component other than the glycol component and / or the glycol component. It can be obtained by appropriately changing the type or composition of the above or by using two or more kinds of the dicarboxylic acid component and / or the glycol component in combination, and there is no particular limitation. For example, terephthalic acid or naphthalenedicarboxylic acid as an aromatic dicarboxylic acid component, polyethylene terephthalate or polyethylene naphthalate composed of ethylene glycol as a glycol component, an aromatic dicarboxylic acid component constituting the polyester, a dicarboxylic acid component other than the glycol component and / or 1 to 3 relative to the total acid component and / or the total glycol component so that the glycol component has the above-mentioned melting point.
Copolymerization of 0 mol% is preferable. More preferably 5 to 20 mol%, still more preferably 7 to 15 mol%
Is. These copolymerization components are not particularly limited, but as the dicarboxylic acid component, for example, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid are preferable, and as the glycol component, for example, ethylene glycol, neopentyl glycol, cyclohexanedimethanol. Is preferred.

The polyester of the present invention preferably has a diethylene glycol content of not more than 1.5% by weight from the standpoint of no deterioration in impact resistance due to heat deterioration during the manufacturing process of the metal can of film or flavor. It is more preferably 1.2% by weight or less, further preferably 1.0% by weight or less, and particularly preferably 0.8% by weight or less.

The polyester of the present invention is germanium,
It is preferable to contain 1 to 500 ppm of at least one element selected from antimony and titanium. More preferably 2 to 400 ppm, still more preferably 3 to 3
It is 00 ppm. If the amount of at least one element selected from germanium, antimony, and titanium is less than 1 ppm, the effect of improving the flavor may not be sufficient, and if it exceeds 500 ppm, foreign matter is generated in the polyester and crystallizes as a crystal nucleating agent. As a result, the impact resistance may be deteriorated, the heat resistance may be reduced, and the polyester may be more colored. The flavor of the polyester of the present invention can be improved by incorporating the specific amount of at least one element selected from germanium, antimony and titanium into the polyester. Among these elements, the germanium element is particularly preferable from the viewpoint of flavor.

The polyester of the present invention, germanium,
The compound used to contain at least one or more elements selected from antimony and titanium is a germanium compound, for example, germanium dioxide, germanium oxide such as germanium hydroxide containing crystal water, hydroxide, or germanium tetramethoxide. Germanium tetraethoxide, germanium tetrabutoxide, germanium alkoxide compounds such as germanium ethylene glycoloxide, germanium phenolate, germanium phenoxide compounds such as germanium β-naphtholate, germanium phosphate, phosphorus-containing germanium compounds such as germanium phosphite, acetic acid Examples thereof include germanium. As an antimony compound,
Examples thereof include diantimony trioxide, antimony trifluoride, antimony acetate, antimony borate, antimony formate, antimonous acid and the like. Titanium compounds include oxides such as titanium dioxide, hydroxides such as titanium hydroxide,
Examples thereof include alkoxide compounds such as tetramethoxy titanate, tetraethoxy titanate, tetrapropoxy titanate, tetraisopropoxy titanate and tetrabutoxy titanate, and glycolide compounds such as tetrahydroxyethyl titanate, phenoxide compounds and acetic acid salts.

The method for incorporating the above elements into the polyester may be any conventionally known method and is not particularly limited. Usually, it is used as a reaction catalyst at any stage before the production of the polyester is completed. It is preferable to add. As such a method, taking the case of germanium as an example, a method of directly adding a powder of a germanium compound or a method of Japanese Patent Publication No.
As described in Japanese Patent Laid-Open No. 34-34, a method of dissolving a germanium compound in a glycol component which is a starting material of polyester and adding it can be mentioned.

From the viewpoint of flavor, the polyester film of the present invention preferably has an acetaldehyde content of 10 ppm or less, more preferably 7 ppm or less,
More preferably 5 ppm or less, particularly preferably 3 pp
m or less. The content of acetaldehyde is 10ppm
If it exceeds, the flavor property may be deteriorated. The method for adjusting the acetaldehyde content to 10 ppm or less is not particularly limited. For example, a polyester obtained by a method of heat-treating the polyester at a temperature not higher than the melting point of the polyester under reduced pressure or in an inert gas atmosphere in order to remove acetaldehyde generated by thermal decomposition when the polyester is produced by a polycondensation reaction or the like. And the like, and preferably, the polyester is solid-phase polymerized at a temperature of 150 ° C. or higher and a melting point or lower under reduced pressure or in an inert gas atmosphere into a film.

From the viewpoint of flavor, the polyester film of the present invention preferably has fewer oligomers composed of a cyclic trimer or the like. In particular, the content of the cyclic trimer is preferably 0.9% by weight or less, more preferably 0.7% by weight or less, and particularly preferably 0.5% by weight or less. The content of oligomers in the film is 0.
If it exceeds 9% by weight, the flavor property may be deteriorated. The method for controlling the content of the oligomer to 0.9% by weight or less is not particularly limited, but it can be achieved by adopting the same method as the method for reducing the acetaldehyde content in the film described above.

The intrinsic viscosity of the polyester in the present invention is preferably 0.50 dl / g or more from the viewpoint that the strength and crystallization of the polyester film are less likely to occur, and no breaking or cracking occurs during the molding of a metal can. It is preferably 2.0 dl / g or less from the viewpoint of facilitating stretching in the film forming step. More preferable range of intrinsic viscosity is 0.5
5 to 1.5 dl / g, particularly preferred range is 0.60
It is 1.0 dl / g. In producing the copolyester of the present invention, a conventionally known reaction catalyst, a color preventing agent can be used, and examples of the reaction catalyst include an alkali metal compound, an alkaline earth metal compound, a zinc compound, a lead compound, Examples of the coloring preventing agent include manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds and the like, and examples thereof include phosphorus compounds and the like.

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

The polyester film of the present invention is
It may be an unstretched sheet or a uniaxially or biaxially stretched film.

The copolyester film of the present invention is
The film can be formed using any conventionally known method.
For example, in the case of a biaxially stretched film, the copolymerized polyester described above is sufficiently dried and then supplied to an extruder, and melt-extruded onto a casting drum to obtain an unstretched film.
Then, a method of biaxially stretching the unstretched film simultaneously or sequentially can be mentioned. In the case of sequential biaxial stretching, the film may be stretched in the longitudinal direction and the width direction, or vice versa. Furthermore, in the sequential biaxial stretching,
It is also possible to perform stretching in the longitudinal direction or the width direction twice or more. The stretching ratio in the longitudinal direction and width direction of the film can be arbitrarily set according to the degree of orientation, strength, elastic modulus, etc. of the target film, but is preferably 2.5 to
It is 5.0 times. Either the stretching ratio in the longitudinal direction or the stretching ratio in the width direction may be increased or may be the same. The stretching temperature may be any temperature in the range of not less than the glass transition temperature of polyester and not more than the crystallization temperature, but it is usually preferably 80 to 150 ° C. Further, the film can be heat-treated after the biaxial stretching. This heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. The heat treatment temperature can be any temperature above the crystallization temperature of the polyester and below the softening point, but it is preferably 120 to 240 ° C. The heat treatment time may be arbitrary, but it is usually preferably 1 to 60 seconds. The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction thereof.

The film containing particles having a deformation degree of 1.1 or more according to the present invention may be a film in which a polyester layer different from the polyester constituting the film according to the present invention is laminated on at least one surface of the film. In particular, a film obtained by laminating a copolyester layer having a melting point difference of 10 to 50 ° C. with respect to the melting point of the copolyester constituting the film of the present invention has improved adhesiveness with a metal plate, impact resistance and heat resistance. It is preferable because When the copolymerized polyester layer having a melting point difference of 10 to 50 ° C. is laminated with a metal plate in the laminated film, the heat resistance is improved when it is higher than the melting point of the copolymerized polyester of the present invention, and when it is low. Adhesion and impact resistance are improved. Furthermore, in the case of a laminated film, particles, catalyst,
Additives such as an antioxidant, a plasticizer, an antistatic agent, a weather resistance agent, and a terminal blocking agent can also be appropriately used.

Further, the thickness of the film of the present invention is not particularly limited, but considering the laminating property to a metal plate and the molding processability of a metal can, it is preferably 5 to 100 μm, more preferably 10 to 80 μm, and particularly preferably. Is 15-50μ
m.

[0035]

The present invention will be described in detail below with reference to examples. The characteristics of polyester and film were measured and evaluated by the following methods.

(1) Primary Particle Diameter of Particles The cross section of polyester or film is observed with a transmission electron microscope, the area equivalent circle diameter of each primary particle is determined, and a value is determined for at least 100 particles and the phase is calculated. The arithmetic mean was taken as the primary particle size.

(2) Average Particle Diameter of Particles The cross section of polyester was observed with a transmission electron microscope, and aggregates (aggregates) formed at intervals smaller than the primary particle diameter were regarded as one particle, and The area circle equivalent diameter was determined, the value was determined for at least 100 particles, and the arithmetic average was taken as the average particle diameter.

(3) Degree of Deformation of Particles in Polyester Film The cross section in the longitudinal direction of the film was observed with a transmission electron microscope to form individual particles or aggregates (aggregates) at intervals smaller than the primary particle size. Consider the thing as one particle,
The maximum length and the minimum length of each particle present in the film were obtained and the ratio was calculated. Further, a value was obtained for at least 100 particles or more, and the arithmetic mean thereof was taken as the degree of deformation.

(4) Content of Germanium, Antimony and Titanium Elements in Polyester The amount of elements and the fluorescent X-ray intensity were quantified by fluorescent X-ray measurement.

(5) Intrinsic viscosity of polyester Dissolve polyester in orthochlorophenol and prepare 25
It was measured at ° C.

(6) Melting point of polyester Crystallized polyester was subjected to a differential scanning calorimeter (DSC-2 type manufactured by Perkin Elmer Co., Ltd.) at 16 ° C./min.
The heating rate was measured.

(7) Content of Diethylene Glycol in Polyester The polyester was amino-decomposed, neutralized and filtered, and then measured by gas chromatography.

(8) Content of acetaldehyde in polyester and film 2 g of fine powder of polyester or film was collected,
Prepared in a pressure-resistant container together with ion-exchanged water, 60 at 120 ° C
After extraction with water for a minute, the amount was quantified by high sensitivity gas chromatography.

(9) Content of Oligomer in Polyester and Film 100 mg of polyester or film was dissolved in 1 ml of orthochlorophenol and liquid chromatograph (V
The amount of the cyclic trimer was measured with an Arian model 8500) to obtain the amount of the oligomer.

(10) Sliding property of polyester film The state of the film laminated on the metal can after molding was observed,
The following criteria evaluated slipperiness. ◎ …… No scratches or shavings are generated on the film ○ …… Scratches or shavings are slightly generated on the film △ …… Scratches or shavings are considerably generated on the film × …… Scratches or shavings are generated on the film Occurrence is remarkable

(11) Heat Resistance of Polyester Film A molded metal can was heated at 210 ° C. for 5 minutes, the state of the film attached to the metal can was observed, and the heat resistance was evaluated according to the following criteria. ◎ …… No peeling or shrinkage on the film ○ …… Slight peeling or shrinking on the film △ …… Peeling or shrinking occurs on the film considerably × …… Peeling or shrinking on the film is remarkable

(12) Impact resistance of polyester film A molded metal can was filled with water and dropped from a height of 1 m onto marble. Ten metal cans were dropped and each metal can was subjected to an electrification test (ERV test), and impact resistance was evaluated according to the following criteria. The energization test is a test in which a dropped metal can is filled with a 1% sodium chloride aqueous solution and the value of a current flowing when a voltage of 6 V is applied to the electrode and the metal can provided in the aqueous solution. ◎ ... 9 or more current value 0.2 mA or less ○ 7 to 8 current value 0.2 mA or less △ …… 5 to 7 current value 0.2 mA or less × …… Less than 5 with a current value of 0.2 mA or less

(13) Flavor of Polyester Film A polyester film cut out into 150 mm × 450 mm was used as a perfume aqueous solution (d-limonene 20 ppm aqueous solution).
The film was heat treated at 80 ° C. for 30 minutes, and the adsorbed amount (μg / g) of d-limonene per 1 g of the film was quantified by gas chromatography to evaluate the flavor of the film. ◎ ・ ・ ・ d-limonene adsorption amount less than 20 ○ …… d-limonene adsorption amount 20 to 25 △ …… d-limonene adsorption amount 25 to 30 × …… d-limonene adsorption amount 30 or more Aqueous solution (d-limonene 20
(ppm aqueous solution), sealed, left for 1 month, then opened and sensory-examined to evaluate changes in odor according to the following criteria. ◎: No change in odor ○: Almost no change in odor △: Change in odor ×: Marked change in odor

Example 1 110 parts by weight of terephthalic acid, 15 parts by weight of isophthalic acid,
Esterification reaction was carried out with 46 parts by weight of ethylene glycol, and 0.01 parts by weight of phosphoric acid and 0.0
17 parts by weight was added, and further 1.5 parts by weight of ethylene glycol slurry containing 10 parts by weight of dry process cohesive silica having a primary particle diameter of 40 nm was added to carry out a polycondensation reaction to obtain a polyester having an intrinsic viscosity of 0.64 dl / g. Got Then, the polyester was allowed to undergo solid phase polymerization reaction at 190 ° C. for 10 hours under reduced pressure, and the intrinsic viscosity was 0.72 dl / g, the melting point was 226 ° C.
A polyester having a germanium element content of 50 ppm was obtained.
This polyester was melt extruded onto a casting drum using an extruder under the conditions of a melting temperature of 270 ° C. and a residence time of 20 minutes to obtain an unstretched film. This unstretched film was stretched 3.5 times in the longitudinal direction at 90 ° C. and then 3.5 times in the width direction at 105 ° C. Further, this biaxially stretched film was heat-treated at 190 ° C. under a constant length to obtain a polyester film having a thickness of 25 μm, a diethylene glycol component amount of 0.8% by weight, an acetaldehyde amount of 4 ppm and an oligomer amount of 0.5% by weight. The degree of deformation of the particles in the film was 7. Table 3 shows the evaluation results of the slipperiness, heat resistance, impact resistance and flavor of this film. As a result, the slidability, heat resistance, impact resistance, and flavor were good.

Examples 2 to 6 Polyester films were obtained in the same manner as in Example 1 except that the polyester composition and contained elements were changed as shown in Table 1. Table 3 shows the evaluation results of the characteristics of this film.

Examples 7 to 10 Polyester films were obtained in the same manner as in Example 1 except that the kind and addition amount of particles were changed as shown in Table 2. Table 3 shows the evaluation results of the characteristics of this film.

Examples 11 and 12 As shown in Table 1, a polyester film was prepared in the same manner as in Example 1 except that particles having a deformation degree in the film of less than 1.1 were used in combination and two kinds of particles were added. Got Table 3 shows the evaluation results of the characteristics of this film. From the results shown in Table 3, since the particles having a deformation degree of less than 1.1 were used in combination, the slipperiness was excellent, but the impact resistance was not as good as in Examples 1-10.

Comparative Example 1 As shown in Tables 1 and 2, a polyester film was obtained in the same manner as in Example 1 except that the particles were not added and the contained element species and the amount were changed. Table 3 shows the evaluation results of the characteristics of this film. As a result, it was difficult to handle because of the absence of particles, and it was not possible to carry out uniform bonding, and peeling, breakage, and scraping from the metal plate occurred during molding, and slipperiness and impact resistance were poor.

Comparative Example 2 As shown in Table 2, a polyester film was obtained in the same manner as in Example 1 except that only one kind of particles having a deformation degree in the film of less than 1.1 was added. Table 3 shows the evaluation results of the characteristics of this film. As a result, the particles were not deformed in the process of drawing characters or bending into a metal can, drawing process, etc., so that the particles fell out and pinholes and cracks caused by them were generated, resulting in poor impact resistance.

[0055]

[Table 1]

[Table 2]

[Table 3]

[0056]

EFFECT OF THE INVENTION The polyester film for laminating metal plates of the present invention is excellent in slipperiness, heat resistance, impact resistance, flavor property, particularly impact resistance and flavor property, and is suitable for a metal plate produced by molding. It can be used preferably.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // C08L 67/02 KJQ C08L 67/02 KJQ

Claims (10)

[Claims] 1. Deformation degree in the film defined by the following formula (1) (ratio of maximum length D to minimum length d of particles)
Contains 1.1 or more particles. A polyester film for laminating metal plates. Deformation degree = D / d (1) 2. The polyester film for laminating metal plates according to claim 1, wherein the particles are aggregated particles having a primary particle diameter of 100 nm or less. 3. The polyester film for laminating metal plates according to claim 1 or 2, wherein the content of the particles is 0.005 to 5% by weight. 4. Inorganic particles having a degree of deformation of less than 1.1 and /
Alternatively, the polyester film for laminating metal plates according to any one of claims 1 to 3, further comprising organic particles. 5. The polyester film for laminating metal plates according to claim 1, wherein the polyester is polyethylene terephthalate or polyethylene naphthalate. 6. The polyester has a diethylene glycol content of 1.5% by weight or less, and germanium,
The polyester film for laminating metal plates according to any one of claims 1 to 5, which contains 1 to 500 ppm of at least one element selected from antimony and titanium. 7. The polyester film for laminating metal plates according to claim 1, wherein the polyester is a copolyester. 8. The polyester is isophthalic acid, 2,6-
The polyester film for laminating metal plates according to claim 7, which is obtained by copolymerizing at least one component selected from naphthalenedicarboxylic acid, aliphatic dicarboxylic acid, aliphatic glycol and alicyclic glycol. . 9. The melting point of polyester is 150 to 250 ° C.
The polyester film for laminating metal plates according to claim 7 or 8, wherein 10. The content of acetaldehyde is 10 pp.
The polyester film for laminating metal plates according to any one of claims 1 to 9, wherein the polyester film has a thickness of m or less.