JP2000297161A - Polyester film for outer surface of molded container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester film which has a high hiding power, is free of unevenness and excellent in beautifulness and has a high abrasion resistance by incorporating a specified amount (per unit thickness) of titanium oxide containing a specified amount of an inorganic and/or an organic surface-treating agent into the same. SOLUTION: This polyester film contains titanium oxide which has an average particle size of 0.1-0.5 μm and is surface-treated with 0.01-2 wt.% inorganic and/or an organic surface-treating agent. The content of titanium oxide per unit thickness of the film is 1.2-2.5 wt.%/μm. If necessary, the film further contains 0.01-2 wt.%/μm cohesion-type inorganic particles having an average particle size of 0.01-10 μm. Preferably, a layer having a titanium oxide concentration of 2-15 wt.%/μm is formed on at least one side of the film in order to reduce the abrasion of a roll, An aluminum oxide compound or an aluminum hydroxide compound in an amount of 0.01-1.5 wt.%, based on titanium oxide, is preferable as the inorganic surface-treating agent. A silicone compound in an amount of 0.02-2 wt.% or a polyhydric alcohol compound in an amount of 0.01-1.5 wt.%, based on titanium oxide, is preferable as the organic surface- treating agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white polyester film for the outer surface of a molded container. More specifically, the present invention relates to a white polyester film for forming a container outer surface, which is useful for processing a film on the outer surface of a container or the like after laminating to a metal plate or the like.

[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 a solution in which various thermosetting resins such as epoxy and phenol are dissolved or dispersed in a solvent.
Coating metal surfaces has been widely practiced. However, such a coating method using a thermosetting resin has unfavorable problems such as a decrease in productivity due to a long time required for drying and environmental pollution due to a large amount of an organic solvent.

Recently, as a method for solving these problems,
Attempts have been made to coat (laminate) a film on a steel plate, an aluminum plate, or a metal plate obtained by subjecting the metal plate to various surface treatments such as plating, which are the materials of the metal can. When a metal can is manufactured by drawing or ironing a film laminated metal plate, the film is required to have the following characteristics. (1) The lamination property to the metal plate is excellent. (2) Excellent adhesion to a metal plate. (3) It has excellent moldability and does not cause defects such as pinholes after molding. (4) The polyester film does not peel off, crack or pinhole due to impact on the metal can.

[0004] In addition, a film used on the outer surface of a metal can is required to have the following characteristics in addition to the above in order to omit the undercoating of a conventionally used white paint. (5) It is excellent in whiteness and metal concealing property, has a beautiful appearance, and is suitable for printing.

[0005] In recent years, with the increase in laminating and canning speeds,
It is desired to further improve laminating properties, moldability, and adhesion between the film and the steel sheet. Particularly, in a white film used for the outer surface of a can, a higher whiteness, a higher degree of concealment, and a beautiful appearance without spots are provided. There is a need for an excellent exterior film.
However, for example, in order to improve the hiding degree, in a white film in which white pigment particles are simply added at a high concentration, the hiding degree is improved, but the film itself becomes brittle, and rupture during stretching frequently occurs, and the film forming property is deteriorated. Problems such as abrasion of a roll used in film formation, and abrasion or breakage of members that come into contact with the film during processing such as lamination or can-making are problematic.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and has a high concealing property as a white polyester film for the outer surface of a molded container, has no spots, is excellent in beauty, Another object of the present invention is to provide a white polyester film for forming a container outer surface which is excellent in abrasion resistance.

[0007]

SUMMARY OF THE INVENTION The present invention provides an inorganic and / or inorganic material.
Or containing titanium oxide surface-treated with an organic surface treating agent, wherein the content of the titanium oxide is 1.2 to 2.5% by weight / μm per film thickness, and the content of the surface treating agent with respect to the titanium oxide It is a white polyester film for an outer surface of a container having an amount of 0.01 to 2% by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester in the present invention is a generic term for high molecular weight compounds constituted by ester bonds. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyl Aromatic dicarboxylic acids such as sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, 5-sodium sulfoisophthalic acid and phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, aliphatic such as dimer acid, maleic acid and fumaric acid Alicyclic dicarboxylic acids such as dicarboxylic acid and cyclohexanedicarboxylic acid, p
And oxycarboxylic acids such as oxybenzoic acid. On the other hand, as the glycol component, for example, ethylene glycol, diethidine glycol, propanediol, butanediol, pentanediol, hexanediol, aliphatic glycols such as neopentyl glycol,
Examples include alicyclic glycols such as cyclohexanedimethanol, aromatic glycols such as bisphenol A and bisphenol S, and diethylene glycol. In addition, two or more of these dicarboxylic acid components and glycol components may be used in combination.

Furthermore, in the present invention, the above polyester is
More than one kind may be blended and used.

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

In the polyester of the present invention, 75 mol% or more of the polyester constituting the film is preferably a polyester containing ethylene terephthalate units and / or ethylene naphthalate units as a component, more preferably from the viewpoint of heat resistance. It is 80 mol% or more, more preferably 85 mol% or more.

The melting point of the polyester film in the present invention is preferably from 180 to 270 ° C, more preferably from 210 to 265 ° C, particularly preferably from 220 to 260 ° C, from the viewpoint of heat resistance and moldability. Here, the melting point of the polyester film refers to a so-called differential temperature calorimetric method (D
SC) is the endothermic peak temperature at the time of melting detected by the first run of SC).

The polyester film of the present invention is not limited to any of an unstretched film, a uniaxially stretched film and a biaxially stretched film, but is preferably a biaxially stretched film in view of heat resistance and dimensional stability. The method of biaxial stretching may be either simultaneous biaxial stretching or sequential biaxial stretching.

In the present invention, from the viewpoint of improving the adhesion between the film and the steel sheet, the amount of the carboxyl terminal group of the polyester B constituting the steel sheet side layer is preferably 25 to 60 equivalents / ton, particularly preferably 30 to 60 equivalents / ton. 55 equivalents / ton.

In the present invention, the IV (intrinsic viscosity) of the polyester is 0.45 in order to further improve the adhesiveness and mechanical properties.
０．７0.75 dl / g, preferably 0.5 to
More preferably, it is 0.7 dl / g, particularly preferably 0.1 dl / g.
More preferably, it is 55 to 0.65 dl / g. If the intrinsic viscosity is less than 0.45 dl / g, it is not preferable because not only the adhesion to the metal plate is reduced, but also the mechanical properties such as elongation are reduced. On the other hand, if the IV exceeds 0.75 dl / g, the quality is excessive, and problems such as a decrease in the productivity of the raw material polymer and an increase in generation of decomposed products during melt extrusion occur.

In the present invention, the white polyester film for forming the outer surface of the container is prepared by adding 1.2 to 2.5 parts by weight of titanium oxide treated with an inorganic and / or organic surface treating agent in view of concealability and processability. % / Μm, preferably 1.4 to 2.2% by weight / μm. Titanium oxide concentration / thickness is 1.2% by weight
If it is less than / μm, the concealing efficiency is reduced, and it is necessary to increase the film thickness in order to obtain the desired concealing property. This is not only inefficient, but also the laminating property and workability deteriorate due to the increase in the film thickness. I do. On the other hand, titanium oxide concentration /
When the thickness exceeds 2.5% by weight / μm, embrittlement of the film and deterioration of film-forming properties become problems.

In the present invention, the inorganic and / or organic surface treating agent needs to be contained in an amount of 0.01 to 2% by weight based on titanium oxide.

Here, as the inorganic surface treating agent, an aluminum component, a silica compound, a titania compound, or the like is used, but the use of an aluminum component is preferable from the viewpoint of dispersibility. When an aluminum component is used, it is preferably 0.01 to 1.5% by weight, more preferably 0.05 to 1% by weight, particularly preferably 0.1 to 1.5% by weight based on titanium oxide.
0.5% by weight. At the time of surface treatment with an aluminum component, it is preferably used as an aluminum oxide compound or an aluminum hydroxide compound. In terms of the amount of aluminum, the aluminum component contained in the aluminum oxide or aluminum hydroxide is 0.1%.
When the content is from 0.01 to 1.5% by weight, the dispersibility and the affinity with the polyester are improved, and the whiteness and the concealing property are excellent. It will be. Further, since the coarse particles are also reduced, roll abrasion during film-forming stretching and trouble during lamination and can-making are eliminated.

As the organic surface treating agent, an amine compound
Products, polyhydric alcohol compounds, silicone compounds, etc.
However, from the viewpoint of dispersibility, polyvalent alcohol
Compounds and silicone compounds are preferred, especially
Properties, in combination with surface treatment agents containing aluminum components
Silicone compounds are preferred from the viewpoint of further improving the dispersibility.
The amount of the silicon compound is 0.02 to the weight of titanium oxide.
To 2% by weight, more preferably 0.1 to 2% by weight.
0.5 to 1% by weight. In addition, polyhydric alcohol compounds
Is 0.01 to 1.5% by weight based on the weight of titanium oxide.
Preferably, more preferably 0.05 to 0.8.
% By weight. By using the above compound as a surface treatment agent,
Foreign matter generation during melt extrusion due to poor dispersibility and titanium oxide
Can be greatly suppressed. Here
The amount of corn compounds and polyhydric alcohol compounds is
The weight ratio (% by weight) to the weight of the tan
The amount of the system compound is thermogravimetric-mass simultaneous analysis and thermogravimetric-gas
Chromium / mass spectrometry at room temperature under helium flow
After heating to 300 ° C at a heating rate of 50 ° C / min, hold for 60 minutes
Of the gas generated attributable to the silicone compound
% By weight based on the weight of titanium oxide, for example (CH
_Three)_ThreeSi⁺, [(CH_Three)_TwoSiO]_Three, [(CH _Three)_TwoSi
O]_FourEtc., but other than silicone
When the gas belonging to the compound is detected, it is also combined.
Shall be. The amount of the polyhydric alcohol compound is calculated by thermogravimetry.
-Simultaneous mass spectrometry and thermogravimetry-Simultaneous gas chromatography / mass spectrometry
Heating rate from room temperature to 50 ° C / min under helium flow
After heating to 300 ° C at a temperature and holding for 60 minutes,
The total amount of generated gas attributed to coal to titanium oxide
%, Such as Butanal, Methylpropenal, Met
hyldihydropyran is an example.
When a gas belonging to a polyhydric alcohol compound is detected,
These shall also be combined.

In the present invention, the titanium oxide concentration / thickness on at least one side is preferably 2 in order to reduce abrasion on a roll or the like.
It is preferable to laminate a layer having a thickness of １５15% by weight / μm, more preferably a titanium oxide concentration / thickness of 3 to 12% by weight / μm. The lamination structure is two layers of A / B, B / A /
B and B / A / C three layers are exemplified, but are not particularly limited. The lamination thickness is preferably from 0.2 to 5 μm, more preferably from 0.5 to 3 μm from the viewpoint of abrasion, and may be on one side, on both sides, or on the lamination surface.

In the present invention, the titanium oxide added to the polyester has an average particle size of 0.1 to 0.5 μm, preferably 0.2 to 0.35 μm. If the average particle size is less than 0.1 μm, the dispersibility in the polyester is reduced, causing problems such as the occurrence of spots. Titanium oxide preferably has a purity of 95% or more, and if less than 95%, dispersibility is poor. The titanium oxide is not limited to any of anatase type and rutile type, but rutile type titanium oxide is preferable from the viewpoint of improving concealing properties.

In the present invention, in order to further improve the dispersibility, it is preferable to pass the molten polymer through a filter during extrusion, and it is particularly preferable to use a multi-stage filter. As the filtration characteristics of the filter, those which filter 30 μm or more are preferable, and those which filter 10 μm or more are particularly preferable.

In the present invention, in addition to the titanium oxide particles, known internal particles having an average particle diameter of 0.01 to 10 μm, particles arbitrarily selected from external particles such as inorganic particles and / or organic particles, An agent can be contained. It is not preferable to use particles having an average particle diameter of more than 10 μm because defects in the film are likely to occur.
Examples of the particles include inorganic particles such as wet and dry silica, colloidal silica, aluminum silicate, calcium carbonate, calcium phosphate, barium sulfate, zinc sulfide, calcium silicate, magnesium carbonate, zinc carbonate, an aluminum component, mica, kaolin, clay, and the like. Organic particles containing styrene, silicone, acrylic acid and the like as constituent components can be exemplified, and from the viewpoint of abrasion resistance, improvement in handleability, and concealability, the content of the aggregated inorganic particles is 0.01 to 2% by weight. Preferably, it is 0.105 to 1% by weight. Further, among the aggregated inorganic particles, the average particle size is 0.5 to
Agglomerated silica particles of 5 μm are preferred, and wet aggregated silica is particularly preferred.
5% by weight is preferred. In the case of lamination, these aggregated inorganic particles are more effective when added to each layer. The particles may be used in combination of two or more kinds as long as the properties are not impaired.

In the present invention, the ratio of elongation in the width direction / longitudinal direction of the white polyester film is preferably 1.05 to 2, more preferably 1.15 to 1.8.
When the elongation in the width direction is high, followability to a roll at the time of lamination is improved, and consequently spots are reduced.

The polyester film of the present invention preferably has an average elongation at break in the longitudinal direction and the width direction of 80% or more, more preferably 90% or more, from the viewpoint of laminating properties and moldability. If the titanium concentration is increased to improve the whiteness, the elongation tends to decrease. If the elongation at break is less than 80%, the film may break at the time of lamination, or may have irregularities in the molding process, or the film may be peeled off after making the can. May cause problems.

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, Titanium compounds and the like as coloring inhibitors include, for example, phosphorus compounds. It is desirable to add an antimony compound, a germanium compound, or a titanium compound as a polymerization catalyst at any stage before the production of the polyester is completed. As such a method, for example, when a germanium compound is taken as an example, a method of adding a germanium compound powder as it is, or as described in JP-B-54-22234, a glycol component which is a starting material of a polyester, A method in which a germanium compound is dissolved and added therein can be used. As the germanium compound, for example, germanium dioxide, germanium hydroxide containing crystal water, or germanium tetramethoxide, germanium tetraethoxide, germanium tetrabutoxide, germanium acoxide compounds such as germanium ethylene glycolide, germanium phenolate,
Examples include germanium phenoxide compounds such as germanium β-naphtholate, phosphorus-containing germanium compounds such as germanium phosphate and germanium phosphite, and germanium acetate. Among them, germanium dioxide is preferable. Examples of the antimony compound include, but are not particularly limited to, antimony oxides such as antimony trioxide, and antimony acetate. Examples of the titanium compound include, but are not particularly limited to, tetraethyl titanate,
Alkyl titanate compounds such as tetrabutyl titanate are preferably used.

For example, a case where germanium dioxide is added as a germanium compound when producing polyethylene terephthalate will be described. The terephthalic acid component and ethylene glycol are subjected to a transesterification or esterification reaction, and then germanium dioxide and a phosphorus compound are added. obtain. Further, preferably, the obtained polymer is subjected to a solid-phase polymerization reaction under reduced pressure or an inert gas atmosphere at a temperature equal to or lower than its melting point to reduce the content of acetoadheride to obtain a predetermined intrinsic viscosity and a carboxyl end group. And the like.

In order to make the polyester contain titanium oxide, for example, a method of adding titanium oxide at the time of synthesis of the polyester, a method of adding titanium oxide to the polyester and melting and kneading the same, or a method of adding a large amount of titanium oxide to the polyester is used. There is a method of producing a concentration master pellet, kneading it with a polyester containing no titanium oxide, and then containing a predetermined amount of titanium oxide. Also in the present invention, the method of adding titanium oxide particles to the polyester is not particularly limited. However, a high-concentration titanium oxide-containing master pellet having a concentration of 45 to 70% by weight is once produced, and is made of a polyester to which titanium oxide has not been added. A method of uniformly mixing the pellets for dilution with an appropriate ratio and supplying the mixture to the extruder can be preferably used from the viewpoint of improving the dispersibility of the particles in the polyester.

The total thickness of the biaxially stretched film of the present invention depends on the moldability after lamination on metal, the coatability on metal,
In terms of impact resistance, it is preferably 3 to 50 μm,
It is more preferably from 5 to 35 μm, particularly preferably from 10 to 30 μm.

The method for producing the biaxially stretched film in the present invention is not particularly limited. For example, after drying each polyester as necessary, it is supplied to a known melt extruder and passed through a desired filter. Then, it is extruded into a sheet form from a slit-shaped die, brought into close contact with a casting drum by a method such as electrostatic application, and cooled and solidified to obtain an unstretched film. The stretching method may be either simultaneous biaxial stretching or sequential biaxial stretching. The unstretched film is stretched in the longitudinal direction and width direction of the film and heat-treated to obtain a film having a desired degree of orientation. From the viewpoint of film quality, a tenter method is preferable, and after stretching in the longitudinal direction, a sequential biaxial stretching method in which the film is stretched in the width direction, and a simultaneous biaxial stretching method in which the film is stretched almost simultaneously in the longitudinal direction and the width direction are desirable. . The stretching ratio is 1.2 to 4.5 times, preferably 1.5 to 4.0 times in each direction. When a film is obtained by sequential biaxial stretching, the stretching in the longitudinal direction is preferably multi-stage stretching, but is not particularly limited. Either the stretching ratio in the longitudinal direction or the stretching ratio in the width direction may be increased, and may be the same. The stretching speed is from 1000% / minute to 200,000%.
And the stretching temperature may be any temperature as long as it is equal to or higher than the glass transition temperature of the polyester and equal to or lower than the glass transition temperature + 100 ° C.
50 ° C. is preferred. After the biaxial stretching, the film is subjected to a heat treatment. This heat treatment can be carried out by any conventionally known method such as in an oven or on a heated roll.
The heat treatment temperature can be any temperature from 120 ° C. to 245 ° C., but is preferably from 120 to 240 ° C. The heat treatment time can be arbitrarily set, but it is usually preferable to perform the heat treatment for 1 to 60 seconds. The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction. Further, re-stretching may be performed once or more in each direction, and then heat treatment may be performed.

It is preferable to improve the adhesiveness by subjecting the film to a surface treatment such as a corona discharge treatment in order to further improve the characteristics.

Various coatings may be applied on the film of the present invention, and the coating compound, method and thickness are not particularly limited as long as the effects of the present invention are not impaired.

The container of the present invention is not particularly limited. For example, a metal plate made of iron, aluminum, or the like is preferable in terms of moldability. 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, a chromium hydrated oxide having a chromium equivalent of 6.5 to 150 mg / m ² in terms of chromium is preferable, and further provided with a spreadable metal plating layer such as nickel, tin, zinc, aluminum, gunmetal, brass and the like. Is also good. 0.5 to 15 mg / m for tin plating
² , 1.8 to 20 g for nickel or aluminum
/ M ² is preferable.

The white film for forming the outer surface of the container according to the present invention may be a beverage can or a food can manufactured by drawing or ironing after laminating to a metal plate or the like by heat laminating or coating the film with an adhesive. It can be suitably used for coating the outer surface of a two-piece metal can. Further, it can be preferably used for covering a lid portion of a two-piece can or a body, a lid, and a bottom of a three-piece can because it has good metal adhesion and moldability.

[0035]

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

(1) Intrinsic viscosity of polyester (IV) Polyester is dissolved in orthochlorophenol,
Measured in ° C.

(2) Titanium Average Particle Diameter The cross section of the film was cut by a transmission electron microscope (TEM).
Observe in the above and process the image of the particles with an image analyzer. The following numerical processing was performed for 1,000 or more particles at different observation points, and the number average diameter D obtained thereby was defined as the average particle diameter. D = ΣDi / N where Di is the equivalent circle diameter of the particles and N is the number of particles.

(3) Melting point The film was treated at 40 ° C. for 60 hours, and after sufficiently removing water, 5 mg was sampled, and the temperature was raised at a rate of 10 ° C./min using a differential scanning calorimeter (DSC2, manufactured by Perkin-Elmer). The peak temperature of melting was defined as the melting point.

The melting point of each layer of the laminated film was determined by scraping each layer with a single blade and measuring the melting point in the same manner as described above.

(4) Amount of Alumina on Titanium Particle Surface After removing the polymer by centrifugation, the weight ratio to titanium oxide was determined by X-ray fluorescence analysis.

(5) Amount of Silicone Compound Using a simultaneous thermogravimetric / mass spectrometry and a thermogravimetric / gas chromatography / mass spectrometry, heating from room temperature to 300 ° C. at a heating rate of 50 ° C./min under helium flow. (CH ₃ ) ₃ Si ⁺ , [(CH ₃ ) ₂ SiO] ₃ , [(C
The total amount of gas generated attributable to H ₃ ) ₂ SiO] ₄ and other silicone compounds was determined and expressed as a percentage with respect to the weight of titanium oxide.

(6) Amount of Polyhydric Alcohol-Based Compound Heating from room temperature to 300 ° C. at a heating rate of 50 ° C./min under helium flow using simultaneous thermogravimetric / mass spectrometry and thermogravimetric / gas chromatography / mass spectrometry. Bu after holding for 60 minutes
The total amount of generated gas belonging to tanal, methylpropenal, methyldihydropyran and other polyhydric alcohol compounds was determined, and expressed as a percentage with respect to the weight of titanium oxide.

(7) Optical Density The optical density of the film was measured with an optical densitometer (Macbeth TR-927).

(8) Spots The difference (R) between the maximum value and the minimum value when measuring the optical density at 100 points at different locations on a 100 cm ² film.
And evaluate it five times with changing the sampling position,
The optical density unevenness was evaluated by an average value of five times.

(9) Dispersibility The dispersed state of the particles was evaluated by observation with a transmission electron microscope. Special Class A: No aggregation is observed. Class A: Some slight aggregation is observed, but no coarse aggregation. Class B: Slight agglomeration is scattered, but nothing leads to coarse agglomeration. Class C: Some are coarsely aggregated. Class D: Many coarsely agglomerated substances are observed.

(10) Concealment After laminating a film on a TFS steel plate (0.2 mm thick) heated to 239 ° C. at 40 m / min, it was rapidly cooled in a 70 ° C. water bath. The L value of the laminated steel sheet was measured by a spectral colorimeter, and the concealability of the steel sheet after lamination was evaluated according to the following criteria. ：: Over 89.0 △: 86.0 or more, 89.0 or less ×: Less than 86.0 (○ or Δ: passed, ×: failed).

(11) Workability The above laminated steel sheet was formed into a coil 5000 m by an ironing forming machine and a drawing forming machine (forming ratio (maximum thickness / minimum thickness) =
2.0, molded in moldable temperature range), can (diameter 6c)
m, height 12 cm). This can was visually evaluated according to the following criteria. ：: No minute crack or breakage is observed. X: Fine cracks and breaks are observed. (○: passed, ×: failed).

(12) Abrasion resistance A film was laminated on a TFS steel plate (thickness: 0.2 mm) heated to 239 ° C. at 40 m / min, and then rapidly cooled in a 70 ° C. water bath. The laminated steel plate was formed into a coil of 5000 m (a reduction in sheet thickness of 55% in a formable temperature range) using an ironing forming machine and a drawing forming machine to obtain a can. At this time, the film surface of the can body was observed with a scanning electron microscope (SEM) at a magnification of 500 to 2000 times, and evaluated based on the following criteria. Special grade A: Streak-like scratches are hardly observed. Grade A: Streak-like scratches are slightly observed. B-Class: Short streak-like scratches are slightly observed. Class C: Long streak-like scratches are clearly seen. Class D: Many long streak-like scratches are observed.

(13) Elongation at break The elongation at break was measured using a Tensilon (tensile tester) with a tensile speed of 300 mm / min, a width of 10 mm and a sample length of 100 mm.

Example 1 As a polyester, rutile type titanium oxide particles (surface treatment: aluminum compound, amine compound, average particle size: 0.1.
Isophthalic acid copolymerized polyethylene terephthalate pellets (copolymerization amount: 12.5 μm.
Mol%) and isophthalic acid copolymerized polyethylene terephthalate pellets containing no titanium oxide particles (copolymerization amount 1
2.5 mol%) and vacuum drying at 160 ° C. for 5 hours, and then mixed at a weight ratio of 4: 6 and supplied to an extruder. The polyester melt-extruded from the extruder was filtered through a multi-stage filter, discharged from a die, cooled and solidified with a mirror-surface cooling drum while applying static electricity, to obtain an unstretched film. This unstretched film is 3.2 mm long at a temperature of 102 ° C.
The film is stretched 3.6 times in the width direction at a preheating temperature of 95 ° C and a stretching temperature of 115 ° C, and then relaxed 5% at 170 ° C.
Heat treatment was performed for 2 seconds to obtain a 14 μm-thick biaxially stretched white polyester film. The film properties are shown in Table 3,
It was good.

Example 2 Films shown in Table 3 were obtained from polyester, titanium oxide and inorganic particles shown in Table 1 under the same conditions as in Example 1. The film properties were good as shown in Table 3.

Example 3 Using polyester and titanium oxide shown in Table 1, Example 1
An unstretched film was obtained in the same manner as described above. This unstretched film is tripled in the longitudinal direction at a temperature of 115 ° C. by a simultaneous biaxial method,
The film was stretched 3.4 times in the transverse direction, relaxed at 180 ° C. for 5%, and heat-treated for 4 seconds to obtain a biaxially stretched white polyester film having a thickness of 14.8 μm shown in Table 3. The film properties were good as shown in Table 3.

Example 4 The polyester, titanium oxide and inorganic particles shown in Table 1 were separately dried, mixed, melted, and filtered by a multi-stage filter in the same procedure as in Example 1, and the layer A was separated from the dies adjacent to each other. And the layer B polymer were co-extruded, laminated and fused, and cooled and solidified by a mirror-surface cooling drum while applying static electricity to obtain an unstretched film. This unstretched film is heated at a temperature of 1
The film is stretched 3.2 times in the longitudinal direction at 02 ° C. and the preheating temperature is 9
After stretching 3.3 times in the width direction at 5 ° C. and a stretching temperature of 120 ° C., relax at 170 ° C. for 5% and heat-treat for 5 seconds, and laminate biaxial stretching of 16 μm thick B / A / B shown in Table 3 A white polyester film was obtained. The film properties were good as shown in Table 3.

Example 5 A biaxially stretched white polyester having a thickness of 16 μm and a thickness of 16 μm as shown in Table 3 was obtained in the same manner as in Example 4 except that the stretching ratio in the width direction was made 3.2 times using the polyester, titanium oxide and inorganic particles shown in Table 1. A film was obtained. The film properties were good as shown in Table 3.

Example 6 A biaxially stretched white polyester having a thickness of 16 μm and a thickness of 16 μm as shown in Table 4 was prepared in the same manner as in Example 4 except that the stretching ratio in the longitudinal direction was set to 3.1 times using the polyester, titanium oxide and inorganic particles shown in Table 2. A film was obtained. The film properties are shown in Table 4,
It was good.

Example 7 An unstretched film was obtained in the same manner as in Example 4 using the polyester, titanium oxide and inorganic particles shown in Table 2. This unstretched film is stretched 3.3 times in the longitudinal direction and 3.15 times in the transverse direction at a temperature of 105 ° C. by the simultaneous biaxial method,
5% relaxation for 5 seconds, heat treatment, thickness 16μ shown in Table 4
m was obtained. The film properties were excellent as shown in Table 4.

Comparative Example 1 A film shown in Table 4 was obtained from polyester, titanium oxide and inorganic particles shown in Table 2 under the same conditions as in Example 1. As shown in Table 4, the film properties were inferior.

Comparative Example 2 Using the polyester, titanium oxide and inorganic particles shown in Table 2, the stretching ratio was set to 1.8 times in the longitudinal direction and 2.1 times in the width direction, and the thickness shown in Table 4 was obtained in the same manner as in Comparative Example 1. A 10 μm thick film was obtained. The film properties were quite poor, as shown in Table 4.

Comparative Example 3 Films shown in Table 4 were obtained from polyester, titanium oxide and inorganic particles shown in Table 2 under the same conditions as in Example 1. As shown in Table 4, the film properties were inferior.

The abbreviations in the table are as follows. PET / I: isophthalic acid copolymerized polyethylene terephthalate Tm: melting point

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

[Table 4]

[0065]

The white polyester film of the present invention is
By defining the titanium oxide concentration / thickness and the surface treatment agent for titanium oxide, the titanium oxide has both concealing properties, beautiful appearance without spots, and abrasion resistance.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08L 67/02 C08L 67/02 // B29C 55/12 B29C 55/12 F term (reference) 4F071 AA43 AA46 AB17 AC16 AD02 AF34 AG12 AG29 AH05 BA01 BB06 BB07 BB08 BC01 BC12 4F100 AA01B AA01C AA01H AA21B AA21C AA21H AB01A AK41B AK41C AK42 AL01 AT00A AT00B AT00C BA03 BA07 BA10C CA13B CA13C CA13H DA01 DE01B DE01C DE01H EJ38 EJ64B EJ64C EJ64H GB16 JK09 JL10 JL10B JL10C JN02 YY00B YY00C 4F210 AA24E AB12 AB16 AB17 AE08 AF15 AG01 AH55 QA02 QC05 QG01 4J002 CF031 CF041 CF051 CF081 CF091 CF141 CF181 DE136 DE146 FB076 FB086 FB096 GG01

Claims (9)

[Claims] 1. A film comprising titanium oxide surface-treated with an inorganic and / or organic surface treating agent, wherein the content of the titanium oxide is 1.2 to 2.5% by weight / μm per film thickness.
m, wherein the content of the surface treating agent with respect to the titanium oxide is 0.01 to 2% by weight. 2. The white polyester film for the outer surface of a container according to claim 1, wherein the inorganic surface treating agent is an aluminum component, and the content relative to titanium oxide is 0.01 to 1.5% by weight. 3. The white polyester film for an outer surface of a container according to claim 1, which contains 0.01 to 2% by weight of aggregated inorganic particles. 4. The organic surface treating agent is a silicone compound and has a content of 0.02 to 2% by weight based on titanium oxide.
The white polyester film for the outer surface of a molded container according to any one of claims 1 to 3. 5. The organic surface treating agent is a polyhydric alcohol compound having a content of 0.01 to 1.0 with respect to titanium oxide.
The white polyester film for a container molding outer surface according to any one of claims 1 to 3, which is 5% by weight. 6. The method according to claim 1, wherein a layer containing 2 to 15% by weight / .mu.m of titanium oxide surface-treated with an inorganic and / or organic surface treating agent is laminated on at least one side. The white polyester film for the outer surface of a container according to the above. 7. The laminated layer contains coagulated inorganic particles of 0.01 to
The white polyester film for the outer surface of a container according to claim 6, which contains 2% by weight. 8. The ratio of elongation in the width direction / longitudinal direction is 1.05-0.5.
The white polyester film for container-molding outer surface according to any one of claims 1 to 7, which is 2. 9. A white polyester film for forming an outer surface of a container according to any one of claims 1 to 8, which is to be bonded to a metal plate.