JPH09323393A - Biaxially oriented polyester film for molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent whiteness, adhesive properties, moldability and cutting resistance in a molding step and suitability for a metal can by laminating at least one layer of a layer A made of polyester containing specific wt.% of colorant and a layer B containing less colorant content than that of the layer A. SOLUTION: A biaxially oriented polyester film for molding needs glossiness of 25 to 110% in view of printability and beauty. Further, it needs an optical density/thickness of 0.04 to 0.1μm in view of printability, moldability and beauty. It is also necessary to laminate at least one layer of the layer B containing less colorant content than that of a layer A on the layer A containing colorant of 20 to 50wt.% on the polyester film. Thus, the film for molding can be used suitably for an outer surface coating of a twopiece metallic can and a three- piece metallic can manufactured by drawing or wiping.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a biaxially stretched polyester film for molding. More specifically, because of its excellent whiteness, moldability, abrasion resistance, and printability, a biaxially oriented polyester for molding suitable for the outer surface of a metal can manufactured by molding such as drawing after being laminated on a metal plate. It's about film.

[0002]

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

As a method of solving these problems, there is a method of laminating a 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. When a three-piece can or a two-piece can is manufactured by using a laminated metal plate of the film as a member, the film for the outer surface of the can has whiteness, adhesion, moldability, abrasion resistance in a molding process, and the like. Characteristics are required.

Many proposals have been made to solve these requirements. For example, JP-A-5-170942 discloses a polyester film having a limited particle concentration and crystal orientation, and JP-A-6-39980. Discloses a polyester film in which a layer containing a low concentration of particles and a layer containing a high concentration of particles are laminated, and JP-A-7-97469 discloses a white polyester film having a low specific gravity for laminating on a metal plate. However, these proposals are not capable of comprehensively satisfying the various required characteristics as described above, and particularly in the case of a film achieving high whiteness, there are problems such as deterioration in adhesion, moldability, and abrasion resistance. was there.

[0005]

The object of the present invention is to eliminate the above-mentioned problems of the prior art, and a biaxially stretched polyester film for molding which is excellent in moldability, particularly whiteness, adhesion and moldability. Another object of the present invention is to provide a biaxially stretched polyester film for molding which is suitable for a metal can having excellent abrasion resistance in the molding process.

[0006]

The above-mentioned objects of the present invention are as follows: glossiness is 25 to 110% and optical density / thickness (μ
m) is a laminated polyester film having a content of 0.04 to 0.1, and at least an A layer made of polyester containing 20 to 50% by weight of a colorant and a B layer having a colorant content smaller than that of the A layer. It can be achieved by a biaxially stretched polyester film for molding which is characterized by being laminated by one layer.

According to the present invention, by obtaining a biaxially stretched laminated polyester film having a specific glossiness and optical density, it is possible to favorably mold it into a three-piece, two-piece can or the like after laminating it on a metal plate. In addition to the above, it was found that good whiteness and abrasion resistance can be obtained. In particular, in terms of satisfying high whiteness, moldability, adhesion, and abrasion resistance, it is extremely superior to the conventional technology. It's a big one.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester in the present invention is a polymer composed of a dicarboxylic acid component and a glycol component, and examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid and diphenyl. Aromatic dicarboxylic acids such as sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, 5-sodium sulfoisophthalic acid, phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer
Acids, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids, p
And oxycarboxylic acids such as oxybenzoic acid. Among these dicarboxylic acid components,
Terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid are preferred from the viewpoint of impact resistance and taste characteristics. On the other hand, glyco
Examples of the alcohol component include aliphatic glycols such as ethylene glycol, propanediol, butanediol, pentanedyl, hexanediol and neopentyl glycol.
And alicyclic glycols such as cyclohexane dimethanol, aromatic glycols such as bisphenol A and bisphenol S, and polyoxyethylene glycols such as diethylene glycol and polyethylene glycol. Among these glycol components, ethylene glycol is preferable from the viewpoint of impact resistance and taste characteristics. Incidentally, two or more of these dicarboxylic acid components and glycol components may be used in combination.

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

The polyester of the present invention has a melting point of 150 to 2
It is preferable that the temperature is 80 ° C. because the heat resistance is improved.

The polyester of the present invention can be produced by any conventionally known method and is not particularly limited. For example, a case where an isophthalic acid component is copolymerized with polyethylene terephthalate and germanium dioxide is added as a germanium compound will be described. A terephthalic acid component, an isophthalic acid component and an ethylene glycol are transesterified or esterified, then germanium dioxide and a phosphorus compound are added, followed by polycondensation reaction at a high temperature and a reduced pressure until a constant diethylene glycol content is obtained, A polymer containing germanium element is obtained.
Then, the obtained polymer is subjected to solid-phase polymerization reaction at a temperature below its melting point under reduced pressure or under an inert gas atmosphere,
Examples thereof include a method of reducing the content of acetoaldehyde and obtaining a predetermined intrinsic viscosity and a carboxyl terminal group.

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

The biaxially stretched polyester film for molding in the present invention has a gloss of 25 to 110%,
It is necessary in terms of printability and beauty. The glossiness is preferably 30 to 100%, particularly preferably 35 to 95%. Examples of the method of obtaining the glossiness of the present invention include controlling the size, concentration, dispersibility, and laminated thickness of the colorant. Preferably, the B layer surface has a gloss of 25 to 110.
% Is preferable in terms of printability and beauty.

Further, in the present invention, the optical density / thickness (μ
m) is 0.04 to 0.1, printability, moldability,
Necessity in terms of beauty. Preferably 0.045-0.
9, particularly preferably 0.05 to 0.8.

The biaxially stretched polyester film for molding in the present invention has the above-mentioned glossiness, optical density / thickness (μm).
In addition to the above, it is necessary that at least one B layer having a colorant content lower than that of the A layer is laminated on the A layer containing 20 to 50% by weight of the colorant in the polyester.

The colorant in the present invention is not particularly limited, but titanium oxides such as rutile type titanium oxide and anatase type titanium oxide, inorganic pigments such as zinc white, zinc sulfate, barium sulfate, alumina and calcium carbonate, known pigments are known. Organic pigments and the like are preferable. In particular, titanium oxide is preferable as the colorant, and the average particle size of the white inorganic pigment is preferably 0.001 to 3 μm, more preferably 0.005 to 2 μm. Here, the average particle diameter is an average particle diameter obtained by observation with an electron microscope.

Various methods can be used as the method of incorporating the colorant into the polyester. As a typical method, it is added in the form of a slurry or powder before, during, or after the start of transesterification or esterification reaction during polyester production, or a slurry or a powder before, during, or after the start of the polycondensation reaction. Examples thereof include a method of adding in the form of a body, a method of adding and melting and mixing in the form of slurry or powder in the system when melt extruding polyester pellets. Furthermore, there is also a method in which a master pellet containing a coloring agent in a high concentration prepared by the method is mixed with a polyester containing no particles or a low concentration so as to have a predetermined concentration of the coloring agent, and then melted. Can be mentioned.

Examples of the polyester used for the layer A in the present invention include the above polyesters, but from the viewpoint of film forming properties of the film, a polyester having 2 to 100 mol% of the structural units as cyclohexylene dimethylene terephthalate units, Polyester having 2 to 100 mol% of constitutional units as butylene terephthalate units, 2-1 to constitutional units
A polyester selected from polyesters having an ethylene naphthalate unit content of 00 mol% is preferable. More preferably, the layer A has 2 to 100 structural units.
It is preferable to form a polyester obtained by mixing a polyester selected from the polyesters containing mol% as the unit with another polyester. Then, the colorant is a polyester having 2 to 100 mol% of the constitutional unit as a cyclohexylene dimethylene terephthalate unit, a polyester having 2 to 100 mol% of the constitutional unit as a butylene terephthalate unit, and a polyester having 2 to 100 mol% of the constitutional unit as ethylene. The naphthalate unit is preferably covered with a polyester selected from polyesters, and another compound such as a surface treatment agent for the colorant may be interposed between the colorant and the polyester. Thus, it is preferable that the colorant is coated on the polyester because the biaxial stretchability is stabilized.

Further, the colorant is substantially 2 to 1 of the constitutional unit.
A polyester having 00 mol% as a cyclohexylene dimethylene terephthalate unit, a polyester having 2 to 100 mol% of the constitutional unit as a butylene terephthalate unit,
It is preferable that the laminated steel is coated with a polyester selected from polyesters having 2 to 100 mol% of the structural units as ethylene naphthalate units, because the formability of the laminated steel sheet is improved. The particle surface coverage is, for example, by dissolving polyester with orthochlorophenol,
After centrifugation of the particles, the dissolved polymer composition and the particle surface polymer composition can be compared and determined.

In the present invention, the melting point of the polyester of the layer A is preferably 246 ° C. or higher, more preferably 248 ° C. or higher and 275 ° C., from the viewpoint of improving abrasion resistance.
It is the following.

Further, from the viewpoint of improving biaxial stretchability and abrasion resistance, a layer B containing a colorant at a lower concentration than the layer A may be laminated in addition to the layer A containing a high concentration of the colorant. It is necessary, and the content of the colorant in the layer B is preferably 1 to 25% by weight. In terms of high whiteness, the colorant content of layer B is 3
-22% by weight is preferable, and 5-20% by weight is particularly desirable.

The film thickness of the present invention is preferably 5 to
The thickness is 30 μm, more preferably 5 to 25 μm, and particularly preferably 6 to 20 μm. The thickness ratio of the A layer and the B layer (A layer / B layer) is preferably 200/1 to
It is 1/1, more preferably 50/1 to 2/1. Further, the ratio d / D of the average particle diameter d of the colorant and the B layer thickness D is preferably 0.001 to 10, and more preferably 0.0.
It is desirable that it is 1-5.

Further, the raw material for collecting the film edge may be contained in the A layer or the B layer.

When the metal plate laminate film of the present invention is formed into a two-piece, three-piece can or the like, it is necessary to laminate the A layer side on the metal plate and the B layer as a specific laminate surface for abrasion resistance. It is preferable in terms. Further, from the viewpoint of adhesiveness, the laminated structure is preferably B layer / A layer / B layer, and in order to further improve the adhesiveness with a metal, B layer / A layer / C layer in which C layer is laminated. Is desirable. C
As the layer, the absolute value of the difference between the melting points of the C layer and the A layer is 10
The temperature is preferably not higher than 0 ° C, and another layer may be interposed between the metal and the C layer. In addition, a structure other than the above-described laminated structure may be used.

When the film B layer of the present invention is used as a non-laminated surface on the outer surface of a metal can, not only the abrasion resistance with other materials that come into contact with the film at the time of can making is improved, but also at the time of transportation, hot bender, etc. It is preferable because it is less likely to be scratched when used in.

Further, the film of the present invention may contain particles other than the colorant in order to improve handleability and processability, and known internal particles having an average particle diameter of 0.01 to 5 μm and inorganic particles. It is optionally selected from external particles such as organic particles and / or organic particles, but may be contained in an amount of 0.01 to 5% by weight.

In the biaxially stretched film of the present invention, the stretching ratio in the longitudinal direction and the width direction can be arbitrarily set according to the degree of orientation, strength, elastic modulus, etc. of the target film.
Simultaneous biaxial stretching by the tenter method and sequential biaxial stretching can be mentioned. The draw ratio in each direction is 1.5 to
It is 5.0 times, preferably 2.0 to 4.0 times. Either the stretching ratio in the longitudinal direction or the stretching ratio in the width direction may be increased, and may be the same. Further, the stretching rate in the longitudinal direction is preferably 2000% / min to 200,000% / min, and the stretching rate in the width direction is preferably 2000 to 20000% / min, and the longitudinal stretching speed> the widthwise stretching speed. Is preferred. The stretching temperature may be any temperature in the range of the glass transition temperature of the polyester or more and the crystallization temperature or less, 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 heating in an oven or on a heated roll. The heat treatment temperature may be any temperature not lower than the crystallization temperature of polyester and not higher than 250 ° C, preferably 120 to 240 ° C.
It is. The heat treatment time can be arbitrary,
Usually, it is preferable to carry out for 1 to 60 seconds. The heat treatment may be performed while relaxing the film in its longitudinal direction and / or width direction. After the heat treatment, the film may be rapidly cooled or gradually cooled. Furthermore, re-stretching may be performed once or more in each direction, and then heat treatment may be performed.

The intrinsic viscosity of the polyester film is preferably 0.4 to 1.0 in view of biaxial stretchability and moldability,
It is more preferably 0.45 to 0.8, and particularly preferably 0.5 to 0.8.

In producing the film of the present invention, additives such as an antioxidant, a plasticizer, an antistatic agent, a weather resistance agent and a terminal blocking agent can be appropriately used if necessary. In particular, the combined use of an antioxidant is preferable because it prevents deterioration of the polyester due to heat history during the can making process. The amount is preferably about 0.001 to 1% by weight based on the total weight of the film.

Further, it is preferable to improve the adhesion by performing a surface treatment such as corona discharge treatment in order to further improve the characteristics, and it is preferable to treat the layer B or the layer C in the laminated film. At that time, the E value is 10 to 50, preferably 20 to 50.

The metal plate of the present invention is not particularly limited,
From the standpoint of formability, tin-free steel plates, tin plates, and metal plates made of aluminum or the like are preferable. Further, in the case of a metal plate made of iron, an inorganic oxide coating layer on the surface thereof for improving adhesion and corrosion resistance, for example, chromic acid treatment, phosphoric acid treatment, chromic acid / phosphoric acid treatment, electrolytic chromic acid treatment A chemical conversion treatment coating layer represented by, for example, a chromate treatment or a chromium chromate treatment may be provided. In particular, a chromium hydrated oxide having a chromium value in terms of metal chromium of 6.5 to 150 mg / m ² is preferable, and a malleable metal plating layer such as nickel, tin, zinc, aluminum, gun metal, or brass may be provided. Good. 0.5 to 15 for tin plating
mg / m ² , 1.8 for nickel or aluminum
Those having a plating amount of ˜20 g / m ² are preferable.

When laminating the film of the present invention on a metal plate, there may be mentioned a method of heating and fusing a metal plate, a method of laminating a film or a metal plate with a primer coat, and the like. When laminating the film of the present invention, another film may be laminated on the opposite surface of the metal plate.

The biaxially stretched film for molding of the present invention can be suitably used for the outer surface coating of two-piece metal cans and three-piece cans produced by drawing or ironing.

[0034]

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

(1) Intrinsic viscosity of polyester Dissolve polyester in orthochlorophenol and prepare 25
Measured in ° C.

When the colorant particles are contained,
The particles were centrifuged and measured.

(2) Melting Point of Polyester The polyester or film was measured at 20 ° C./mi by a differential scanning calorimeter (DSC-2 type manufactured by Perkin Elmer Co.).
It was measured at a heating rate of n.

(3) Average particle size of particles The resin is removed from the film by a plasma low temperature ashing method to expose the particles. The processing conditions are selected so that the resin is incinerated but the particles are not damaged. The number of the particles was observed at 5,000 to 10,000 using a scanning electron microscope, and the particle image was obtained from the equivalent circle diameter by an image processing apparatus.

When the particles are particles such as internal particles that are difficult to confirm, the particles were determined by a transmission microscope instead of the above method.

(4) Layer thickness An ultrathin section was prepared and observed by a transmission electron microscope.
In this case, a known dyeing method or the like may be used in combination so as to clearly confirm the layer.

(5) Thickness Measured using an electronic micrometer.

(6) Optical Density It was measured using an optical densitometer (TR927 manufactured by Macbeth).

(7) Glossiness It was determined using Nippon Denshoku Industries Co., Ltd. (VG107, angle 60 °).

(8) Formability A steel sheet heated to 140 to 280 ° C. was laminated with a film on both sides, rapidly cooled, and then formed into a can by a drawing machine (forming ratio (maximum thickness / minimum thickness) = 2.0). Obtained. The beauty of the obtained can was judged as follows.

Grade A: No scratches such as cracks are found. Class B: 1 to 5 shallow scratches / can can be seen, but there is no problem. Class C: 5 or more shallow scratches / can are seen. Class D: Many deep scratches and cracks occur.

(9) Scratch resistance The amount of white powder generated after 100 cans were made was judged as follows.

Grade A: No white powder was observed. Class B: An extremely small amount of white powder was observed, but there was no problem. Class C: A small amount of white powder was observed. Class D: A large amount of white powder is observed.

(10) Printability After printing, 100 cans were printed in 6 colors and the beauty after printing was judged as follows.

Grade A: Printing is clear and no defects are observed. Class B: Printing is clear and there are few defects. Class C: Printing is unclear, but there are almost no defects. Class D: Printing is unclear and defects are observed.

Example 1 Cyclohexanedimethanol was used as polyester in an amount of 30.
Molten% copolymerized polyethylene terephthalate (intrinsic viscosity 0.80) and surface-treated rutile type titanium oxide (average particle size 0.2 μm) powder were melt mixed at 270 ° C. using a vacuum vent type twin-screw extruder, and then oxidized. After making master pellets containing 70% by weight of titanium, the chips are
It was treated at 20 to 130 ° C. for 30 minutes to obtain crystallized pellets. Furthermore, isophthalic acid 12.0 mol% copolymerized polyethylene terephthalate (germanium catalyst, intrinsic viscosity 0.69, diethylene glycol 0.91% by weight, melting point 228 ° C.) was polymerized, and the resulting pellets were heated with a high-speed stirrer to 120- It was treated at 130 ° C. for 20 minutes to obtain crystallized pellets. These pellets were mixed so that the titanium oxide content would be 30% by weight, vacuum dried at 150 ° C. for 3 hours, and supplied to a single-screw extruder (layer A). Further, the pellets were mixed, dried and supplied to another single-screw extruder so that the titanium oxide content was 15% by weight (layer B). These polymers are melted at 270 ° C as a separate flow path and
Layers / A layers / B layers (laminating ratio 1/10/1) are stacked, discharged from the die, and then statically applied (7 kv) to cool and solidify on a mirror surface cooling drum (25 ° C.) before unstretching. I got a film. This unstretched film is stretched at a temperature of 100 ° C. and a stretching speed of 1
The film was stretched 3.3 times in the longitudinal direction at 0000% / min and the temperature was 11
A film having a thickness of 12 μm was drawn at 0 ° C. at a drawing rate of 3000% / min in the width direction by 3.2 times, then relaxed at 180 ° C. for 5% for 5 seconds, cooled at 80 ° C. for 5 seconds and then cooled to room temperature. Wound up. On the other hand, as a film to be laminated on both sides of a steel sheet, an isophthalic acid-copolymerized polyethylene terephthalate film (thickness) which was heat-treated at 180 ° C. after longitudinal stretching (95 ° C., 3.0 times stretching), lateral stretching (108 ° C., 2.9 times stretching) 20 μm, plane orientation coefficient = 0.110,
Mp 228 ° C) was used. The characteristics are as shown in Table 1, and good whiteness, moldability, and abrasion resistance could be obtained.

Examples 2 to 10 and Comparative Examples 1 to 3 Films were obtained in the same manner as in Example 1 except that the type of polyester, the laminated structure of the film and the film forming conditions were changed.

The results are shown in Tables 1 to 4.

In Example 2, the titanium oxide used in the B layer was changed to B layer / A layer / B layer (stacking ratio 2/8/2), in the same manner as in Example 1 for film formation and characteristics. When evaluated,
As shown in Table 1, the glossiness was lowered and the abrasion resistance was slightly lowered.

In Example 3, the master pellet in the layer A, the pellet obtained by crushing and melting after collecting the master pellet, and the polymer for dilution were mixed to obtain a titanium content of 21% in the layer.
When the film formation and characteristics were evaluated in the same manner as in Example 1 except that the titanium content of the layer B was set to 5% by weight, the whiteness was slightly decreased and the printability was decreased as shown in Table 1.

In Example 4, master pellets were made of polybutylene terephthalate (intrinsic viscosity 1.20) and
Film formation and characteristics evaluation were carried out in the same manner as in Example 1 except that layers were formed and the colorant content and thickness of each layer were changed. Further, the polyester of the layer A was dissolved with orthochlorophenol, and the particles were centrifuged, and then the dissolved polymer composition and the particle surface polymer composition were compared. As a result, the particle surface had a high polybutylene terephthalate concentration and was obtained as shown in Table 2. The film properties were good.

In Example 5, master pellets were prepared using 12.8 mol% isophthalic acid copolymerized polyethylene terephthalate (antimony catalyst, intrinsic viscosity 0.70, diethylene glycol 0.51 wt%, melting point 226 ° C.), Polybutylene terephthalate as a polymer for dilution,
Film formation and property evaluation were carried out in the same manner as in Example 4 except that 12.0 mol% of isophthalic acid copolymerized polyethylene terephthalate was used. As a result, polyester was dissolved in orthochlorophenol and particles were centrifuged, and then dissolved polymer composition was obtained. When the particle surface polymer compositions were compared, the particle surface had a low polybutylene terephthalate concentration, and the film characteristics obtained as shown in Table 2 tended to deteriorate slightly.

In Example 6, polyethylene terephthalate containing 3 mol% of diethylene glycol as the master pellet (germanium catalyst, intrinsic viscosity 1.0, melting point 249 ° C.)
Isophthalic acid 5 was prepared by using
Mol% copolymerized polyethylene terephthalate (antimony catalyst, intrinsic viscosity 0.68, diethylene glycol 0.5
1 wt%, melting point 244 ° C), layer A, layer B
The colorant content of the layer was changed, and a film was formed in the same manner as in Example 1. Furthermore, as a film to be laminated on both sides of a steel sheet, longitudinal stretching (110 ° C., 3.0 times stretching), lateral stretching (1
A polyethylene terephthalate film (2.0 mol% of diethylene glycol, thickness 25 μm, plane orientation coefficient = 0.11) which was heat-treated at 185 ° C. after being stretched at 15 ° C. and 2.9 times.
5, melting point 256 ° C.) was used. When the characteristics were evaluated,
As shown in Table 2, the obtained film characteristics were good although the moldability was slightly lowered.

In Example 7, the titanium oxide was changed to prepare a film having a titanium content of B layer of 27% by weight. As shown in Table 3, the glossiness was lowered, and the moldability, abrasion resistance, and printability were slightly lowered.

In Example 8, the polyester was changed, the laminated constitution was B layer / A layer, the colorant contents of A layer and B layer were changed, and A layer was laminated on a metal plate and evaluated. As shown in Table 3, the formability and the abrasion resistance were slightly lowered.

In Example 9, the laminated structure was B layer / A layer / C.
When the layer C and the layer C were 10% by weight of titanium oxide, good characteristics were obtained as shown in Table 3.

In Comparative Example 1, when the polyester was changed and the particle content of the layer B was 0.5% by weight,
As shown in Table 4, the glossiness becomes 130%, and the abrasion resistance is
Printability deteriorated.

In Comparative Example 2, when the polyester was changed and the particles and the concentration of the B layer were changed, the glossiness was remarkably lowered as shown in Table 4, and the abrasion resistance and the moldability were deteriorated.

In Comparative Example 3, when the polyester and particles of the A layer were changed to form a monolayer film having a titanium oxide concentration of 15% by weight, printability and abrasion resistance deteriorated.

In Example 10, master pellets were prepared from polyethylene naphthalate (intrinsic viscosity 0.78) and PET (weight ratio = 1: 4) at a melting temperature of 295 ° C. and mixed with polyethylene terephthalate (melting point 258 ° C.). 295
A film was formed by extrusion at ℃. The melting point main peak of the layer A of the obtained film was 247 ° C., and particularly excellent whiteness and abrasion resistance were exhibited.

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

[Table 3]

[0068]

[Table 4]

[0069]

[Table 5]

The abbreviations in the table are as follows.

PET / CHDM: cyclohexanedimethanol copolymerized polyethylene terephthalate (numerals are copolymerized mol%) PET / I: isophthalic acid copolymerized polyethylene terephthalate (numbers are copolymerized mol%) PET / DEG: diethylene glycol copolymerized polyethylene terephthalate ( Numbers are copolymer mol%) PET: Polyethylene terephthalate PBT: Polybutylene terephthalate

[0072]

The present invention relates to a biaxially stretched polyester film for molding of the present invention. More specifically, since it has excellent whiteness, moldability, abrasion resistance, and printability, it can be suitably used for a metal can manufactured by forming such as draw forming after laminating on a metal plate.

Claims (10)

[Claims] 1. A glossiness of 25 to 110% and an optical density /
A laminated polyester film having a thickness (μm) of 0.04 to 0.1, comprising an A layer made of polyester containing 20 to 50% by weight of a colorant, and a B layer having a colorant content smaller than that of the A layer. A biaxially stretched polyester film for molding, which is obtained by laminating at least one layer. 2. The biaxially stretched polyester film for molding according to claim 1, wherein the polyester of the layer A contains 2 to 100 mol% of its constitutional units as cyclohexylene dimethylene terephthalate units. 3. The biaxially stretched polyester film for molding according to claim 1, wherein the polyester of the layer A has 2 to 100 mol% of its constitutional units as butylene terephthalate units. 4. The biaxially stretched polyester film for molding according to claim 1, wherein the polyester of the layer A has 2 to 100 mol% of its constitutional units as ethylene naphthalate units. 5. The main peak of melting of the polyester of the layer A is 246 ° C. or higher, and
The biaxially stretched polyester film for molding according to any one of 1. 6. A biaxially stretched polyester film for molding, wherein the colorant is substantially coated with the polyester according to any one of claims 2 to 4. 7. The biaxially stretched polyester film for molding according to claim 1, wherein the colorant content of the B layer is 1 to 25% by weight. 8. The biaxially stretched polyester film for molding according to claim 1, wherein the laminated structure is a B layer / A layer. 9. The biaxially stretched polyester film for molding according to claim 1, wherein the laminated structure is B layer / A layer / C layer. 10. The biaxially stretched polyester film for molding according to claim 1, wherein the biaxially stretched polyester film is molded after being heat laminated on a metal plate.