WO2011021563A1

WO2011021563A1 - Polyester film for molding

Info

Publication number: WO2011021563A1
Application number: PCT/JP2010/063689
Authority: WO
Inventors: 西河博以; 齋藤智久
Original assignee: 三菱樹脂株式会社
Priority date: 2009-08-17
Filing date: 2010-08-12
Publication date: 2011-02-24
Also published as: JP2011037192A

Abstract

Provided is an inexpensive polyester film which has excellent moldability, particularly moldability under a low temperature and a low pressure, has excellent solvent resistance, heat resistance, and light resistance, and imposes little environmental stress and is ideal for use in nameplates for home appliances and automobiles and in building materials. The polyester film contains a UV absorber formed from benzotriazole or cyclic imino ester and has a light transmittance of 1% or less at a wavelength of 350 nm. The polyester film is a laminated polyester film comprising a base layer B and at least one layer A adjacent to the layer B. The melting point of the base layer B (TmB) is within a range of 180ºC to 225ºC, the melting point of the layer A (TmA) is higher than the melting point of the base layer B, and the difference between said melting points (TmA - TmB) is within the range of 10ºC to 40ºC.

Description

Polyester film for molding

The present invention is excellent in moldability, particularly moldability under low temperature and low pressure, and excellent in solvent resistance, heat resistance and light resistance, and has a small environmental load, for example, for home appliances, automobile nameplates or building members. It is related with the polyester film for shaping | molding which can be used suitably as.

Conventionally, as a sheet for molding, a polyvinyl chloride film is typical and has been preferably used in terms of workability, but the film has a problem of generation of toxic gas when the film burns due to a fire or the like. However, there are problems such as bleed-out of plasticizers, and new materials with a small environmental load have been demanded due to recent needs for environmental resistance.

In order to satisfy the above requirements, unstretched sheets made of polyester, polycarbonate and acrylic resin have been used in a wide range of fields as non-chlorine materials. In particular, unstretched sheets made of a polyester resin are widely used because of their excellent mechanical properties, transparency, and economy. For example, unstretched polyester-based sheets containing polyethylene terephthalate and a substantially non-crystalline polyester-based resin in which the ethylene glycol component is replaced with another component are disclosed (for example, Patent Documents 1 to 5).

The above-mentioned unstretched polyester sheet satisfies market demands regarding moldability and laminate suitability, but because it is an unstretched sheet, it does not have sufficient heat resistance and solvent resistance and satisfies the high demands of the market. It hasn't been done yet.

As a method for solving the above problems, a method using a biaxially stretched polyester film is clearly shown, and it is known that the moldability is particularly excellent at a low temperature and a low pressure (for example, Patent Documents 6 to 8).

As a method for imparting light resistance, a method of adding an ultraviolet absorber is known (for example, Patent Documents 9 to 11).

Although the above polyester film satisfies the market demand for light resistance, it is not sufficient in satisfying both moldability and solvent resistance because it has a single-layer film structure, and it is highly demanded by the market. Not yet satisfied.

JP-A-9-156267 JP 2001-71669 A Japanese Patent Laid-Open No. 2001-80251 JP 2001-129951 A JP 2002-249651 A JP-A-64-40400 Japanese Patent Laid-Open No. 7-196821 JP-A-8-3227 Japanese Patent Laid-Open No. 2000-309652 JP 2003-111538 A Japanese Patent Laid-Open No. 2003-221606

The present invention has been made in view of the above circumstances, and the problem to be solved is excellent moldability, particularly moldability under low temperature and low pressure, and excellent in solvent resistance, heat resistance, light resistance, and environment. An object of the present invention is to provide a low-loading polyester film for molding that can be suitably used as, for example, a home appliance, an automobile nameplate or a building member.

As a result of intensive investigations in view of the above problems, the present inventors have found that the above problems can be easily solved by a film having a specific configuration, and the present invention has been completed.

That is, the gist of the present invention is a polyester film containing a UV absorber made of benzotriazole or a cyclic imino ester and having a light transmittance of 1% or less at a wavelength of 350 nm, the polyester film comprising: a base layer B; A laminated polyester film having at least one layer A adjacent to the layer B, wherein the base layer B has a melting point (TmB) in the range of 180 to 225 ° C., and the layer A has a melting point (TmA) of the base layer B The molding polyester film is characterized by having a melting point higher than the melting point and a difference in melting point (TmA−TmB) in the range of 10 to 40 ° C.

According to the present invention, the moldability, particularly the moldability under a low temperature and a low pressure, the solvent resistance, the heat resistance, the light resistance, and the environmental load are small, for example, for home appliances, automobile nameplates or construction The polyester film for molding which can be favorably used as a member for use can be provided at low cost, and the industrial value of the present invention is high.

Hereinafter, the present invention will be described in detail.
The polyester constituting the film of the present invention is preferably terephthalic acid as the dicarboxylic acid component. Besides these, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, One or more known dicarboxylic acids such as naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, and cyclohexanedicarboxylic acid may be included as a copolymerization component. As the diol component, ethylene glycol is preferable. Besides these, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, One or more known diols such as neopentyl glycol may be included as a copolymerization component.

In the present invention, it is effective to adjust the amount of the third component in order to keep the melting point of each layer in the specified range.

Examples of the polymerization catalyst include antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds, and titanium compounds. Titanium compounds include, for example, tetraalkyl titanates, tetraaryl titanates, titanyl oxalate salts, titanyl oxalate, chelate compounds containing titanium, titanium tetracarboxylates, and specifically tetraethyl titanate, tetrapropyl titanate, tetraphenyl Examples thereof include titanate or a partial hydrolyzate thereof, titanyl ammonium oxalate, potassium titanyl oxalate, titanium triacetylacetonate and the like.

In addition, it is preferable to add inorganic particles, organic salt particles and crosslinked polymer particles to the polyester film of the present invention. Inorganic particles that can be used include calcium carbonate, kaolin, talc, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, Examples thereof include lithium fluoride. On the other hand, examples of the organic salt particles include calcium oxalate, terephthalate such as calcium, barium, zinc, manganese, and magnesium. Examples of the crosslinked polymer particles include divinylbenzene, styrene, acrylic acid, methacrylic acid, acrylic acid or a methacrylic acid vinyl monomer homopolymer or copolymer. In addition, organic particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting urea resin, and thermosetting phenol resin may be used.

The shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

The method for adding particles to the polyester is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage for producing the polyester, but the polycondensation reaction may proceed preferably after the esterification stage or after the transesterification reaction. Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

In addition to the above-mentioned particles, conventionally known antioxidants, heat stabilizers, lubricants, antistatic agents, fluorescent brighteners, dyes, pigments, and the like are added to the polyester film in the present invention as necessary. be able to.

The film of the present invention contains an ultraviolet absorber made of benzotriazole or cyclic imino ester, and the light transmittance at a wavelength of 350 nm is required to be 1% or less. The light transmittance is preferably 8% or less, more preferably 0.6% or less. By imparting this property, it is possible to prevent the polyester film layer from deteriorating particularly when exposed to sunlight outdoors. Moreover, benzotriazole or cyclic imino ester is used for the ultraviolet absorber used from a viewpoint of heat resistance and economical efficiency.

Examples of the benzotriazole ultraviolet absorber include 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl). ) Phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyhexyl) phenyl ] -2H-benzotriazole, 2- [2′-hydroxy-3′-tert-butyl-5 ′-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5′-tert -Butyl-3 '-(methacryloyloxyethyl) phenyl]- H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl ] -5-methoxy-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-cyano-2H-benzotriazole, 2- [2'-hydroxy-5'- (Methacryloyloxyethyl) phenyl] -5-tert-butyl-2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -5-nitro-2H-benzotriazole However, it is not particularly limited to these.

Examples of the cyclic imino ester ultraviolet absorber include 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazin-4-one), 2-methyl-3,1-benzoxazine. -4-one, 2-butyl-3,1-benzoxazin-4-one, 2-phenyl-3,1-benzoxazin-4-one, 2- (1- or 2-naphthyl) -3,1- Benzoxazin-4-one, 2- (4-biphenyl) -3,1-benzoxazin-4-one, 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2-p-benzoylphenyl -3,1-benzoxazin-4-one, 2-p-methoxyphenyl-3,1-benzoxazin-4-one, 2-cyclohexyl-3,1-benzoxazin-4-one, 2-p- ( Or -) Phthalimidophenyl-3,1-benzoxazin-4-one, 2,2 '-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), 2,2'- Bis (3,1-benzoxazin-4-one), 2,2'-ethylenebis (3,1-benzoxazin-4-one), 2,2'-decamethylenebis (3,1-benzoxazine- 4-one), 2,2′-p-phenylenebis (3,1-benzoxazin-4-one), 2,2′-m-phenylenebis (3,1-benzoxazin-4-one), 2, 2 '-(4,4'-diphenylene) bis (3,1-benzoxazin-4-one, 2,2'-m-phenylenebis (3,1-benzoxazin-4-one, 2,2'- (2,6- or 1,5-naphthalene) bis (3,1 Benzoxazin-4-one), 2,2 '-(2-methyl-p-phenylene) bis (3,1-benzoxazin-4-one), 2,2'-(2-nitro-p-phenylene) Bis (3,1-benzoxazin-4-one), 2,2 ′-(2-chloro-p-phenylene) bis (3,1-benzoxazin-4-one), 2,2 ′-(1, 4-cyclohexylene) bis (3,1-benzoxazin-4-one), 1,3,5-tri (3,1-benzoxazin-4-one-2-yl) benzene, 1,3,5- Tri (3,1-benzoxazin-4-one-2-yl) naphthalene, 2,4,6-tri (3,1-benzoxazin-4-one-2-yl) naphthalene, 2,8-dimethyl- 4H, 6H-benzo (1,2-d; 5,4-d ′) bis- (1, 3) -Oxazine-4,6-dione, 2,7-dimethyl-4H, 9H-benzo (1,2-d; 5,4-d ′) bis- (1,3) -oxazine-4,9- Dione, 2,8-diphenyl-4H, 8H-benzo (1,2-d; 5,4-d ′) bis- (1,3) -oxazine-4,6-dione, 2,7-diphenyl-4H , 9H-benzo (1,2-d; 5,4-d ′) bis- (1,3) -oxazine-4,6-dione, 6,6′-bis (2-methyl-4H, 3,1 -Benzoxazin-4-one), 6,6'-bis (2-ethyl-4H, 3,1-benzoxazin-4-one), 6,6'-bis (2-phenyl-4H, 3,1 -Benzoxazin-4-one), 6,6′-methylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), , 6′-methylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-ethylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6′-ethylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-butylenebis (2-methyl-4H, 3,1-benzoxazin-4-one) 6,6′-butylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-oxybis (2-methyl-4H, 3,1-benzoxazin-4-one) 6,6′-oxybis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-sulfonylbis (2-methyl-4H, 3,1-benzoxazin-4-one) ), 6,6'-sulfonyl (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,6′-carbonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,6 ′ -Carbonylbis (2-phenyl-4H, 3,1-benzoxazin-4-one), 7,7'-methylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7 '-Methylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one), 7,7'-bis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7 '-Ethylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), 7,7'-oxybis (2-methyl-4H, 3,1-benzoxazin-4-one), 7, 7'-sulfonylbis (2-methyl-4H, 3 , 1-benzoxazin-4-one), 7,7′-carbonylbis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,7′-bis (2-methyl-4H, 3,1-benzoxazin-4-one), 6,7′-bis (2-phenyl-4H, 3,1-benzoxazin-4-one), 6,7′-methylenebis (2-methyl-4H, 3,1-benzoxazin-4-one), and 6,7′-methylenebis (2-phenyl-4H, 3,1-benzoxazin-4-one).

When blending the above UV absorber into a film, it is exposed to high temperatures in the extrusion process, so the UV absorber uses a UV absorber with a decomposition start temperature of 290 ° C. or more to reduce process contamination during film formation. Preferred above. When an ultraviolet absorber having a decomposition start temperature of less than 290 ° C is used, the decomposed product of the ultraviolet absorber adheres to the roll group of the manufacturing apparatus during film formation, so that it may be reattached to the film or scratched. May be a flaw.

The total thickness of the polyester film of the present invention is not particularly limited because it is appropriately selected depending on the use for which the polyester film of the present invention is used, but is preferably 12 from the viewpoint of mechanical strength, handling properties, and productivity. ~ 100 μm.

The polyester film used as the base material of the present invention needs to have a multilayer structure. By forming at least one outer layer as a skin layer that is resistant to solvents, both moldability and solvent resistance can be achieved.

In the case of a film having a laminated structure of three or more layers, it is preferable that the ultraviolet absorber is blended in the polyester layer constituting the surface layer because the ultraviolet absorbing effect is high.

The method for achieving the multilayer structure is not particularly limited, but two or three or more layers of films are obtained by a so-called coextrusion method using two or three or more melt extruders because of its economical efficiency. It is preferable.

In the present invention, a polyester film having a base layer B and at least one outer layer A adjacent to the B layer, wherein the base layer B has a melting point (TmB) in the range of 180 to 225 ° C., and the melting point of the layer A ( TmA) is higher than the melting point of the base layer B, and the difference between the melting points (TmA−TmB) needs to be 10 to 40 ° C. When the melting point (TmB) of the base layer is less than 180 ° C., a phenomenon such as opening or tearing often occurs when used at a high temperature, resulting in poor heat resistance. When the melting point (TmB) of the base layer is higher than 225 ° C., the film is not deformed particularly at low temperature and low pressure, and the moldability is poor. When the difference in melting point (TmA-TmB) is less than 10 ° C, the solvent resistance necessary for the surface treatment on the film is given, and the film has poor moldability, etc. It is difficult to do. When the difference in melting point (TmA−TmB) is larger than 40 ° C., a phenomenon occurs in which a crack occurs between the base layer B and the outer layer A when the film is deformed, and peeling occurs at the interface.

In the film of the present invention, coating layers such as an antistatic layer, an adhesive layer, and an oligomer precipitation preventing layer may be provided as long as the gist of the present invention is not impaired.

When the coating layer is provided, it is preferably provided by in-line coating. In-line coating is a method of coating within the process of producing a polyester film. Specifically, it is a method of coating at any stage from melt-extrusion of polyester to biaxial stretching, heat setting and winding. is there. Usually applied to either a substantially amorphous unstretched sheet obtained by melting and quenching, a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction), or a biaxially stretched film before heat setting. To do. In these, the method of extending | stretching to a horizontal direction after apply | coating to a uniaxially stretched film is excellent. According to such a method, since film formation and coating / drying can be performed simultaneously, there is a merit in manufacturing cost, thin film coating is easy to perform stretching after coating, and heat treatment performed after coating is not limited. Since the high temperature is not achieved by this method, the coating film and the polyester film are firmly adhered.

The thickness of the coating layer is usually 0.001 to 10 μm, preferably 0.010 to 5 μm, and more preferably 0.015 to 2 μm as the thickness after drying. When the thickness of the coating layer is less than 0.001 μm, the effect such as antistatic may not be sufficiently improved. When the thickness of the coating layer exceeds 10 μm, so-called blocking may occur in which the coating layer acts like an adhesive and the films wound up on the roll adhere to each other.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

(1) Intrinsic viscosity:
A measurement sample was dissolved in a solvent of phenol / tetrachloroethane = 50/50 (parts by weight) to prepare a solution having a concentration c = 0.01 g / cm ³ , and a relative viscosity η _r with the solvent was measured at 30 ° C. The intrinsic viscosity [η] was determined.

(2) Polyester composition:
The polyester film was dissolved in deuterated trifluoroacetic acid and analyzed by ¹ H-NMR method to determine isophthalic acid content and 1,4-cyclohexanedimethanol content.

(3) Thickness:
Obtained with a micrometer.

(4) Melting peak temperature (Tm):
Accompanied by melting obtained when a temperature difference of about 5 mg of a polyester resin is raised from 0 ° C. to 300 ° C. at a rate of 20 ° C./minute using a differential scanning calorimeter “MDSC 2920 type” manufactured by TA Instruments Inc. The temperature of the endothermic peak was Tm. Of the melting peak temperatures obtained by the above-mentioned method, only the outer layer (A layer) of the formed film was sampled and measured, and the melting peak temperature was defined as the matte outer layer A (TmA), and the outer layer of the formed film ( The melting peak temperature obtained from the film from which layer A) was removed was taken as the melting point (TmB) of base layer B, and the difference in melting points = (TmA) − (TmB) was determined.

(5) 350 nm transmittance:
The light transmittance in the ultraviolet region with a wavelength of 350 nm was measured using a spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC).

(6) Heat resistance as a film for molding:
A release layer is formed on the polyester film, a mold having a length of 35 cm, a width of 25 cm, and a maximum depth of 3.0 cm is used. After preheating with an IR heater, the mold is preliminarily prepared by vacuum or pressure molding. Molding was performed. The heat resistance was evaluated according to the following criteria based on the state of melting of the film by preheating.
○: It can withstand the processing temperature and can be used for preforming.
(Triangle | delta): Although it can respond to preforming, the expansion | swelling by film softening generate | occur | produces rarely.
X: Perforation due to film melting or expansion due to film softening frequently occurs.

(7) Solvent resistance as a film for molding:
As a substitute evaluation of defects occurring during printing, the polyester film was cut out, immersed in toluene for 30 seconds, and evaluated according to the following criteria.
○: There is no change in transparency and the like compared to the sample before immersion.
(Triangle | delta): Transparency falls a little compared with the sample before immersion.
X: The transparency is clearly reduced (whitened) as compared with the sample before immersion.

(8) Formability as a film for molding:
Molds having different depths were used in the preforming process, and evaluation was performed based on the mold following ability.
A: A mold having a depth of 2.0 cm is formed with a uniform thickness without causing film breakage or cracking.
Δ: A mold having a depth of 2.0 cm cannot be molded with a uniform thickness due to film breakage, cracking, or the like, but a mold having a depth of 1.0 cm can be molded with a uniform thickness.
X: A mold having a depth of 1.0 cm cannot be molded with a uniform thickness due to film breakage, crack generation, or the like.

(9) Interfacial peeling evaluation:
As a substitute evaluation for interfacial peeling, which frequently occurs during molding, evaluation was performed according to the following criteria.
That is, a tensile test under an atmosphere of 100 ° C. was evaluated 5 times (10 times in total) in the longitudinal and lateral directions of the sample, and the evaluation was performed according to the following criteria.
○: The phenomenon that only the surface layer breaks does not occur.
Δ: The phenomenon that only the surface layer breaks occurs once or more and less than 5 times.
X: The phenomenon which only the surface layer fractures occurs 5 times or more.

(10) Light resistance evaluation:
Using a sunshine weather meter (Suga Test Instruments Co., Ltd., WEL-SUN-HCL type), irradiate the resulting polyester film for 1000 hours (equivalent to 1 year of outdoor exposure) according to JIS-K-6783b. Thus, an outdoor exposure promotion test was conducted. Thereafter, the color difference (ΔE value) was measured according to JIS Z8730. The smaller the color difference (ΔE value), the smaller the color change before and after the light irradiation, that is, the better the light resistance.
○: ΔE value is less than 2 Δ: ΔE value is less than 5 ×: ΔE value is 5 or more

Next, the polyester raw material used in the following examples will be described.
<Polyester 1>
Using terephthalic acid as the dicarboxylic acid component and ethylene glycol as the polyhydric alcohol component, a polyester chip containing no lubricant particle size and having an intrinsic viscosity of 0.66 dl / g by a conventional melt polymerization method was produced.

<Polyester 2>
Using terephthalic acid as the dicarboxylic acid component and ethylene glycol as the polyhydric alcohol component, 0.60 part of amorphous silica having an intrinsic viscosity of 0.66 dl / g and an average particle diameter of 2.5 μm by a conventional melt polymerization method The contained polyester chip was produced.

<Polyester 3>
A raw material containing 0.50 part of amorphous silica having an average diameter of 2.5 μm polymerized by a conventional melt polycondensation method using isophthalic acid and terephthalic acid as dicarboxylic acid components and ethylene glycol as a polyhydric alcohol component, respectively. Chips were manufactured. The isophthalic acid content in the dicarboxylic acid component of this raw material was 16 mol%.

<Polyester 4>
Using diphthalic acid components as isophthalic acid and terephthalic acid, and polyhydric alcohol components as ethylene glycol, raw material chips polymerized by a conventional melt polycondensation method were produced. The isophthalic acid content in the dicarboxylic acid component of this raw material was 22 mol%.

<Polyester 5>
Using terephthalic acid as the dicarboxylic acid component and 1,4-cyclohexanedimethanol and ethylene glycol as the polyhydric alcohol component, raw material chips polymerized by a conventional melt polycondensation method were produced. The 1,4-cyclohexanedimethanol content in the diol component of this raw material was 33 mol%.

<Polyester 6>
A UV absorbent-containing polyester chip was prepared by adding 10% by weight of Siasorb UV-3638 (CAS No. 18600-59-4) manufactured by Nippon Cytec Industries, Ltd. to polyester 1, and kneading in an extruder.

<Polyester 7>
A UV absorbent-containing polyester chip was prepared by adding 10% by weight of Siasorb UV-3638 (CAS No. 18600-59-4) manufactured by Nippon Cytec Industries Co., Ltd. to polyester 4 and kneading in an extruder.

Example 1:
Polyester 3 and polyester 6 are blended at a weight ratio of 40:60, melted in an extruder, supplied to the outer layer A of the laminated die, and polyester 1, polyester 4 and polyester 5 are fed to the inner layer B of the laminated die. : 30:50 by weight ratio. The extrusion rate ratio of the outer layer A and the inner layer B is supplied at a ratio of 4:46, and two types and three layers of laminated polyester resin composed of the outer layer A / inner layer B / outer layer A are extruded into a film and cooled at 35 ° C. An unstretched film cast on a drum and rapidly solidified was produced. Next, after preheating with a heating roll at 80 ° C., the infrared heating heater and the heating roll were used in combination, and the film was stretched 3.2 times in the vertical direction between 85 ° C. rolls. Then, the film was stretched 4.2 times in the transverse direction while being heated at a temperature of 110 ° C., subjected to a heat treatment at 190 ° C. for 10 seconds, and simultaneously relaxed by 10% in the width direction to obtain a polyester film having a thickness of 50 μm. The properties of the obtained film were as shown in Table 1. From these results, it was found that both heat resistance and solvent resistance were good, moldability and interfacial peeling were satisfactory, and light resistance was excellent.

Example 2:
In Example 1, the raw materials supplied to the outer layer A were polyester 2 and polyester 7 40:60, and the raw materials supplied to the inner layer B were polyester 1: polyester 4: polyester 5 5:50:45. In the same manner as in Example 1, a 50 μm thick polyester film was obtained.

Example 3:
In Example 1, a polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the raw materials supplied to the outer layer A were 40:60 for polyester 3 and polyester 6.

Example 4:
In Example 1, a polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the raw materials supplied to the outer layer A were 40:60 for polyester 2 and polyester 6.

Example 5:
In Example 2, a polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the raw material supplied to the outer layer A was 10:30:60 for polyester 2, polyester 4 and polyester 7.

Example 6:
In Example 2, a polyester film having a thickness of 50 μm was obtained in the same manner as in Example 2 except that the raw materials supplied to the outer layer A were 40:15:45 for polyester 3, polyester 4, and polyester 6.

Comparative Example 1:
A polyester film having a thickness of 50 μm was obtained in the same manner as in Example 2 except that the raw materials supplied to the outer layer A in Example 2 were changed to 60:40 for polyester 1 and polyester 3. The obtained film was greatly inferior in light resistance.

Comparative Example 2:
In Example 1, a polyester film having a thickness of 50 μm was obtained in the same manner as in Example 2 except that the raw material supplied to the outer layer A was 40:30:30 for polyester 3, polyester 4 and polyester 6. The obtained film was inferior in light resistance.

Comparative Example 3:
In Example 4, a polyester film having a thickness of 50 μm was obtained in the same manner as in Example 4 except that the raw materials supplied to the inner layer B were 55:45 for polyester 1 and polyester 4. The obtained film was inferior in moldability.

Comparative Example 4:
In Example 1, a polyester film having a thickness of 50 μm is obtained in the same manner as in Example 1 except that polyester 5 and polyester 7 are 40:60 as raw materials supplied to the outer layer A and polyester 5 is used as a raw material supplied to the inner layer B. It was. The obtained film was inferior in heat resistance and solvent resistance.

Comparative Example 5:
In Example 4, a polyester film having a thickness of 50 μm was obtained in the same manner as in Example 4 except that the raw materials supplied to the inner layer B were polyester 1 and polyester 4 of 25:75. The obtained film was inferior to interfacial peeling, and tears, etc. that were considered to be caused by this property occurred frequently even when it was actually molded.

Comparative Example 6:
In Comparative Example 4, a polyester film having a thickness of 50 μm was obtained in the same manner as in Example 4 except that the raw material supplied to the inner layer B was 30:70 for polyester 4 and polyester 5. Although heat resistance improved compared with the comparative example 4, it was still inferior to solvent resistance.

Comparative Example 7:
Except that polyester 1, polyester 2, polyester 4, and polyester 6 were blended in a weight ratio of 40: 5: 50: 5, melted in an extruder, and a polyester resin composed of a single layer was extruded into a film. A polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1. The obtained film was inferior in moldability.

Comparative Example 8:
Except that polyester 3, polyester 4, polyester 5, and polyester 7 were blended at a weight ratio of 5: 35: 55: 5, melted in an extruder, and a polyester resin composed of a single layer was extruded into a film. A polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1. The obtained film was inferior in solvent resistance.

The film of the present invention can be suitably used, for example, as a member for home appliances, automobile nameplates, or construction.

Claims

A polyester film containing a UV absorber composed of benzotriazole or a cyclic imino ester and having a light transmittance of 1% or less at a wavelength of 350 nm, the polyester film comprising a base layer B and a layer A adjacent to the layer B The base layer B has a melting point (TmB) in the range of 180 to 225 ° C., the layer A has a melting point (TmA) higher than the melting point of the base layer B, and the difference between the melting points A polyester film for molding, wherein (TmA-TmB) is in the range of 10 to 40 ° C.
The molding polyester film according to claim 1, wherein an ultraviolet absorber having a decomposition start temperature of 290 ° C or higher is used.
The polyester film for molding according to claim 1 or 2, wherein the polyester layer containing the ultraviolet absorber constitutes a surface layer.