JP2001277351A - Biaxially oriented polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film excellent in heat resistance, transparency and mechanical physical properties and absorbing ultraviolet rays. SOLUTION: The biaxially oriented polyester film contains 0.01-10 weight % of an ultraviolet absorber represented by formula 1 (wherein, R is a hydrogen atom, an alkyl group, an alkyl group substituted with a halogen atom or an alkoxy group or a benzyl group; and R' is a hydrogen atom or a methyl group) and having a 10% weight reducing temperature of 300 deg.C or higher and the light transmissivity at a wavelength of 360 nm thereof is 30% or less and the thickness thereof is 10-200 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially oriented polyester film, and more particularly, to a biaxially oriented polyester film having an ultraviolet-cutting property and excellent in transparency, heat stability and mechanical properties. Things.

[0002]

2. Description of the Related Art Polyester films, especially biaxially oriented films typified by polyethylene terephthalate, have excellent physical and scientific properties, and are used for base films of magnetic recording media, capacitor derivatives, packaging, plate making, It is widely used as a base material for insulation and photography. However, polyethylene terephthalate has a high transmittance in the ultraviolet region, and when used for packaging, the contents are colored by ultraviolet light, and when used outdoors as a cover for printed materials, the color of the printed material is irradiated by ultraviolet light. In order to cause discoloration or to color polyethylene terephthalate itself, studies have been made to mix various ultraviolet absorbers.

As an ultraviolet absorbing material used for these purposes, for example, a polyethylene terephthalate film containing a benzophenone type, a benzotriazole type, a salicylic acid type, a hydroquinone type or the like is known. However, the films containing these conventional UV absorbers have insufficient heat resistance or poor UV absorbing ability, so that the UV absorber is decomposed or sublimated when the film is formed. And the problem that the ultraviolet absorbing ability is not sufficiently exhibited.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a biaxially oriented polyester film having excellent heat resistance, transparency, mechanical properties, and ultraviolet absorbing ability. It is to be solved.

[0005]

Means for Solving the Problems In view of the above problems, the present inventors have studied various ultraviolet absorbers and found that a biaxially oriented film using a specific ultraviolet absorber has improved heat resistance, transparency, The inventors have found that the mechanical properties, ultraviolet absorbing ability and the like can be satisfied simultaneously and sufficiently, and have completed the present invention.

That is, the gist of the present invention is that the following formula (I)
A 0.01% to 10% by weight of an ultraviolet absorber having a 10% weight loss temperature of 300 ° C. or higher, a light transmittance at a wavelength of 360 nm of 30% or less, and a film A biaxially oriented polyester film having a thickness of 10 to 200 μm.

[0007]

Embedded image

(In the above formula, R is a hydrogen atom and has 1 carbon atom.
2 to 6 carbon atoms substituted with an alkyl group, a halogen atom or an alkoxy group having 1 to 12 carbon atoms
Represents an alkyl group or a benzyl group, and R ′ represents a hydrogen atom or a methyl group.)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The polyester resin referred to in the present invention is a polyester resin in which the bifunctional acid component is mainly composed of an aromatic dicarboxylic acid or an ester-forming derivative thereof. Specifically, terephthalic acid, 2,6-naphthalenedicarboxylic acid Acids and their ester-forming derivatives include dimethyl terephthalate, 2,6
-Dimethyl naphthalenedicarboxylate and the like are selected according to the intended use. Of these, terephthalic acid and dimethyl terephthalate are preferably selected.

The glycol component includes ethylene glycol, butylene glycol, propylene glycol, polyethylene glycol, 1,4-cyclohexanedimethanol and the like, and ethylene glycol and butylene glycol are preferred.

The polyester resin comprises one kind of aromatic dicarboxylic acid or an ester-forming derivative thereof,
The polyester may be a polyester starting from a different glycol component, or may be a copolymer containing two or more components. In addition to the above as components to be copolymerized, for example, diol components such as diethylene glycol, neopentyl glycol, polyalkylene glycol, adipic acid, sebacic acid, phthalic acid, dicarboxylic acid components such as isophthalic acid, trimellitic acid, pyromellitic acid And the like are selected according to the application.

In the present invention, it is preferable to use a polyester having an ultraviolet absorbing ability in order to reduce the content of the ultraviolet absorbing agent and to enhance the ultraviolet absorbing ability. Particularly, a polyester containing 1 to 10 mol% of an ethylene naphthalate unit is preferable. If the ethylene naphthalate unit is less than 1 mol%, the ultraviolet absorbing ability tends to be insufficient, and if it is 10 mol% or more, the crystallinity of the polyester is lost, and various problems may occur. By using a polyester having an ultraviolet absorbing ability and a specific ultraviolet absorbing agent in combination, a particularly excellent ultraviolet absorbing film can be obtained.

The method for obtaining a polyester containing an ethylene naphthalate unit is not particularly limited, and a method in which a copolymer having a predetermined ethylene naphthalate unit is used as it is or a method in which a copolymer having a predetermined composition is used by blending. And the like.

The film of the present invention has an intrinsic viscosity of 0.40.
０．８0.80, furthermore 0.45 to 0.75, especially 0.5
0 to 0.70 is preferred. If the intrinsic viscosity is less than 0.40, the inherent mechanical strength of the polyester cannot be obtained, and if it exceeds 0.75, the melt viscosity will increase, making it impossible to apply to the extruder or filter in the extrusion process. May be large.

The greatest feature of the present invention is that a specific ultraviolet absorber is used. Since the triazine compound as the ultraviolet absorber has extremely high temperature resistance, the melting temperature is 26%.
Even when it is blended into a polyethylene terephthalate film having a temperature of about 0 to 300 ° C., it is suitable without sublimation.

In the above formula (I), R represents 1 to 18 carbon atoms.
When it is an alkyl group, it may be a linear or branched alkyl group, and it may be, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a 2-ethylbutyl group, It may be a heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl, tetradecyl or octadecyl group.

R is a halogen or a group having 1 to 12 carbon atoms.
When it is an alkyl group having 2 to 6 carbon atoms, which is substituted with an alkoxy group, for example, 2-chloroethyl group, 2-fluoroethyl group, 2-methoxyethyl group, 2-ethoxyethyl group, 2-isopropoxyethyl Group, 2-methoxypropyl group, 3-butoxypropyl group, 2-butoxyethyl group, 2-hexyloxyethyl group, 2-octyloxyethyl group or 2-dodecyloxyethyl group.

In the present invention, R represents 1 to 1 carbon atoms.
Preferred are an alkyl group of 2 or a benzyl group, an alkyl group of 3 to 6 carbon atoms, particularly a propyl group.

In the formula (I), R ′ is preferably a hydrogen atom.

As a particularly preferred example, 2-
(4,6-diphenyl-1,3,5-triazine-2-
Yl-)-5- (hexyl) oxyphenol.

The ultraviolet absorbent used in the present invention comprises 1
0% weight loss temperature of 300 ° C. or more, preferably 320 ° C.
As described above, the temperature is more preferably 340 ° C. Polyester is usually blended with an ultraviolet absorber or melted at a temperature of 260 ° C. to 300 ° C. in the extrusion process of the film forming process. The UV absorber sublimates or lowers the molecular weight of the polyester. Further, in the film forming process, sublimates adhere to rolls of the film forming machine. In particular, when it adheres to the casting roll, the adhesion between the drum and the film is deteriorated, the thickness fluctuation and the like become severe, and the film cannot be formed.

The amount of the ultraviolet absorber added to the polyester film is 0.01 to 10% by weight, preferably 0.05 to 5% by weight, more preferably 0.10 to 3% by weight. If the amount of the ultraviolet absorber is less than 0.01% by weight, the ability to absorb ultraviolet rays is inferior, and if it exceeds 10% by weight, the mechanical strength of the polyester film is undesirably reduced.

The polyester film of the present invention has a light transmittance in the ultraviolet region of 360 nm of 30% or less, preferably 20% or less, more preferably 10% or less. If the light transmittance at 360 nm exceeds 30%, ultraviolet rays pass through the polyester film, and therefore, when used for packaging, the contents cannot be protected from ultraviolet rays, which is not preferable.

The polyester film of the present invention may be a single layer or a laminate, and can be selected according to the purpose of use. In particular, a layer containing an ultraviolet absorber was used as an intermediate layer.
The layer structure is an effective means for preventing bleed out of the ultraviolet absorbent. In addition, the total thickness of the film is usually 10 to 200 μm irrespective of the single-layer structure or the laminated structure.
Range. When the total thickness of the film is less than 10 μm, the ultraviolet absorbing ability becomes insufficient, and when it exceeds 200 μm,
Stretching during film formation may be mechanically difficult.

The film of the present invention imparts an appropriate sliding property to the film in order to improve the workability in the winding step and various steps in the production of the film.

More specifically, for example, 0.01 to 2.0% by weight, preferably 0.1% by weight of fine particles having an average particle size of 0.05 to 2.0 μm is added to the film to appropriately roughen the surface. ~
1.5% by weight is contained.

Examples of such fine particles include calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, lithium phosphate, magnesium phosphate, lithium fluoride, aluminum oxide, silicon oxide, titanium oxide, kaolin, talc, and carbon black. , Silicon nitride, boron nitride, and JP-B-59-52
Examples thereof include, but are not limited to, crosslinked polymer fine powders as described in JP-A-16.

At this time, the fine particles to be blended may be a single component or two or more components may be used simultaneously. When two or more components are used, it is preferable that the total average particle diameter and the content thereof are within the above-mentioned ranges.

The average particle size is less than 0.05 μm,
When the content of the fine particles is less than 0.01% by weight, the surface of the film is insufficiently roughened, and the effect may not be sufficiently obtained. Further, when the average particle size exceeds 2.0 μm or when the content exceeds 2.0% by weight, the degree of surface roughening of the film surface may be too large or the transparency of the film may be deteriorated. .

The method of blending the above particles with the raw polyester is not particularly limited. For example, a method of adding each particle to the polyester polymerization step or a method of melt-kneading the raw polyester and each particle is preferable. In this case, an ultraviolet absorber may be added at the same time.

The surface roughness (Ra) of the film obtained when the fine particles are added is preferably 3 to 50 nm.
When the surface roughness (Ra) is less than 3 nm, the film has poor slipperiness, and thus tends to have poor winding characteristics and workability in the film forming process. Also, when it exceeds 50 nm,
The transparency of the film tends to be poor.

The polyester film of the present invention may contain, if necessary, an antistatic agent, a coloring agent, an antioxidant, an antifoaming agent,
Additives such as a fluorescent whitening agent and flame retardancy may be blended.

One or both surfaces of the polyester film of the present invention may be subjected to an anti-reflection treatment. The anti-reflection treatment may be embossing treatment by forming minute irregularities on the surface, light of reflected wave. For example, a thin film forming process using interference may be used. Further, if necessary, a coating treatment for the purpose of imparting lubricity, releasability, antistatic property, easy adhesion, and the like can be performed.

In particular, in applications where high transparency is required, the amount of particles added to increase the transparency of the film may be reduced. In this case, the slipperiness of the film is sacrificed. It is effective to coat a lubricating layer for the purpose of imparting a smoothness.

The polyester film of the present invention is obtained, for example, by subjecting a polyester to melt extrusion in a conventional manner, successively or simultaneously biaxially stretching, and, if necessary, stretching it in the vertical or horizontal direction again. It can be obtained by heat setting or aging if necessary.

The biaxially oriented polyester film of the present invention thus obtained is used as a substrate for packaging, plate making, photography, and the like, and is particularly suitable for applications requiring ultraviolet absorption.

[0038]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. The methods for measuring physical properties used in the present invention are shown below. (1) Average particle size of fine particles Centrifugal sedimentation type particle size distribution analyzer SA- manufactured by Shimadzu Corporation
The particle size was measured using a CP3 type by the sedimentation method based on Stokes' resistance law. The average particle size was determined using a value of 50% of the integrated (volume basis) in the equivalent spherical distribution of the particles obtained by the measurement. The particle size distribution value (r) was calculated from the following equation.

Particle size distribution value (r) = d ₂₅ / d ₇₅ (in the above formula, d ₂₅ and d ₇₅ are the integrated volumes of the particle groups measured from the large particle side, and are 25% and 75% of the total volume of each particle group, respectively). (2) Intrinsic viscosity 1 g of the polymer was phenol / tetrachloroethane = 50.
/ 50 (weight ratio) in 100 ml of a mixed solvent.
It was measured at 0 ° C. (3) Film thickness A film specimen having a width W (cm) and a length L (cm) was prepared, the specimen weight was defined as G (g), the density d (g / cm ³ ), and the film thickness t was determined. (Μm) was calculated by the following equation.

T = G / (W × L × d) × 10000 (4) Weight loss by 10% Using a thermal analyzer (DT-20Bs, Shimadzu Corporation) under nitrogen gas flow (200 ml / min) 1 from room temperature
Heat to 360 ° C. at a heating rate of 0 ° C./min.
The% reduced temperature was read. (5) Light transmission Double beam spectrophotometer (UV manufactured by Shimadzu Corporation)
-3100PC), the light transmittance was continuously measured in the wavelength range of 350 to 600 nm, and the light transmittance at the wavelength of 360 nm was detected. (6) Tensile test (F2 and F5 values) Tensile tester Intesco Model 20 manufactured by Intesco Corporation
A sample film having a length of 50 mm and a width of 15 mm was pulled at a rate of 50 mm / min in a room controlled at a temperature of 23 ° C. and a humidity of 50% RH using a mold 01, and 2%, and 5%.
The strength at% elongation was defined as F2 value and F5 value, respectively. (7) Surface roughness (Ra) The surface roughness was defined as the center line average roughness Ra (μm).
It was obtained as follows using a surface roughness measuring instrument (SE-3F) manufactured by Kosaka Laboratory Co., Ltd. That is, the reference length L (2.5 mm) is measured in the direction of the center line from the film cross-section curve.
, And the center line of the extracted part is the x-axis,
When the roughness curve is represented by y = f (x) using the direction of the vertical magnification as the y-axis, the value given by the following equation is represented by [μm]. The center line average roughness was obtained by calculating ten cross-sectional curves from the surface of the sample film, and expressing the average value of the center line average roughness of the sampled portion obtained from these cross-sectional curves. In addition, the tip radius of the stylus is 2 μm, the load is 30 mg, and the cut-off value is 0.
08 mm.

[0041] Ra = (1 / L) ∫ 0 L 0 | f (x) | was the dx (8) continuous film resistant continuous film-forming property was evaluated separately to the rank of following.

A: Continuous film formation was possible without any problems, and no adhesion of sublimates caused by the ultraviolet absorber was observed after film formation. A: Continuous film formation was possible without breakage, but after film formation. Sublimate due to ultraviolet absorber was adhered to the roll. △: Sometimes breakage occurred due to the sublimate, so that continuous film formation could not be performed. ×: Sublimate was severely generated and breakage occurred frequently. (9) Practical characteristics Color inkjet printer (B manufactured by Canon Inc.)
JC-420J), a polyester film was stuck to the printing surface of the paper printed, left for one week in a place exposed to sunlight, and the printed matter was observed and evaluated according to the following rank.

：: little change in color was observed Δ: slight change in color was observed X: color changed drastically Example 1 (Polyester-A: Production of polyethylene terephthalate) 100 parts by weight of dimethyl terephthalate And 60 parts by weight of ethylene glycol as starting materials, 0.09 parts by weight of magnesium acetate tetrahydrate as a catalyst was placed in a reactor, the reaction starting temperature was set to 150 ° C., and the reaction temperature was gradually increased with the distillation of methanol. After 3 hours, the temperature was raised to 230 ° C. After 4 hours, the transesterification reaction was substantially terminated. 0.04 parts of ethyl acid phosphate and 0.04 parts of antimony trioxide were added to the reaction mixture to give 4
A time polycondensation reaction was performed. Then, after adding 0.04 parts of ethyl acid phosphate, the average particle diameter was 0.7.
0.006 parts of amorphous silica particles dispersed in μm ethylene glycol and 0.04 parts of antimony trioxide were added, and a polycondensation reaction was performed for 4 hours. That is, if the temperature is 23
The temperature was gradually raised from 0 ° C to 280 ° C. On the other hand, the pressure was gradually reduced from the normal pressure, and finally was 0.3 mmHg.
After 4 hours from the start of the reaction, the reaction was stopped and the polymer was discharged under nitrogen pressure. The intrinsic viscosity of the obtained polyester was 0.65. (Production of Polyester-B: Polyethylene Naphthalate) Dimethyl naphthalene-2,6-dicarboxylate 100
Parts, 65 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. The temperature was raised to substantially complete the transesterification reaction. Then phosphoric acid 0.04
Parts, 0.04 part of antimony trioxide was added, followed by a polycondensation reaction according to a conventional method to obtain a polymer having an intrinsic viscosity of 0.55, followed by solid phase polymerization, and finally, polyethylene naphthalate of 0.63 was obtained. Obtained. (Polyester-C: masterbatch containing ultraviolet absorber) The obtained polyester-A and 2- (4,6-diphenyl-1,3,5-triazin-2-yl-)-5-
(Hexyl) oxyphenol was kneaded and mixed using a vented twin-screw extruder to a concentration of 5% by weight to prepare polyethylene terephthalate containing an ultraviolet absorber. (Formation of polyester film) Polyester-A8
0 parts, polyester-B 10 parts, polyester-C1
0 parts are blended and dried at 170 ° C. for 3 hours and then 280 ° C.
Melt at a temperature of from 300 to 300 ° C and feed to an extruder at 280 ° C
From a die through a gear pump and a filter at a temperature of 30 ° C. to a casting drum set at a surface temperature of 30 ° C., and a thickness of 56 mm using an electrostatic application cooling method.
An amorphous sheet of 0 μm was obtained.

Next, the amorphous sheet was heated at 84 ° C. in the longitudinal direction.
Stretched 3.7 times longitudinally, stretched 4.0 times at 75 ° C in the horizontal direction, and heat-treated at 90 ° C for 3 seconds to obtain a biaxially oriented film having a thickness of 38 µm and containing 8.1 mol% of ethylene naphthalate. Manufactured.

Example 2 (Formation of Polyester Film) Polyester-A 8
0 parts, 20 parts of polyester-C are blended, and 170 parts
After drying at 280 ° C for 3 hours, the material is melted at a temperature of 280 ° C to 300 ° C, fed to an extruder, and passed through a gear pump and a filter at 280 ° C to 300 ° C. Then, an amorphous sheet having a thickness of 560 μm was obtained using an electrostatic application cooling method.

Next, the amorphous sheet was heated at 84 ° C. in the longitudinal direction.
The film was longitudinally stretched 3.7 times, stretched 4.0 times at 75 ° C. in the horizontal direction, and heat-treated at 90 ° C. for 3 seconds to produce a biaxially oriented film having a thickness of 38 μm.

Examples 3 to 6 and Comparative Examples 1 to 5 The same procedures as in Example 2 were carried out except that the ultraviolet absorber, the amount of the ultraviolet absorber added, and the film thickness were changed to Tables 1 and 2 below. A polyester film was obtained by the method. In Comparative Examples 4 and 5, films could not be obtained. The properties of the obtained film are shown in Table 3 below.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

According to the film of the present invention, a biaxially oriented polyester film having excellent heat resistance, transparency, mechanical properties and ultraviolet absorbing ability can be provided, and its industrial value is high.

Claims (3)

[Claims] 1. A light beam having a wavelength of 360 nm, comprising an ultraviolet absorbent comprising a hydroxyphenyltriazine compound represented by the following formula (I) and having a 10% weight loss temperature of 300 ° C. or higher: 0.01 to 10% by weight. 30% transmittance
A biaxially oriented polyester film, wherein the film thickness is 10 to 200 μm. Embedded image (In the above formula, R represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkyl group having 2 to 6 carbon atoms substituted with a halogen atom or an alkoxy group having 1 to 12 carbon atoms, or a benzyl group. R ′ represents a hydrogen atom or a methyl group) 2. The method according to claim 1, wherein the ultraviolet absorbent is 2- (4,6-diphenyl-1,3,5-triazine- represented by the following formula (II):
The biaxially oriented polyester film according to claim 1, which is 2-yl-)-5- (hexyl) oxyphenol. Embedded image 3. The polyester according to claim 1, wherein the polyester contains 1 to 10 mol% of ethylene naphthalate units.
The biaxially oriented polyester film according to the above.