JP2003175577A - Biaxially oriented polyester film for being pasted on window - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shielding film for being pasted on window, wherein fading/discoloration is less after use for a long period of time without using an ultraviolet ray absorbing material or a radical absorbing agent. <P>SOLUTION: This biaxially oriented polyester film for being pasted on window is a co-extruded laminated film comprising at least three layers of polyester. In this case, the biaxially oriented polyester film contains a dye which substantially dissolves with polyester in the intermediate layer, and the ultraviolet ray absorbing agent or the radical absorbing agent is not contained in either one of the layers. Then, a color tone variation ΔE*ab when the film is directly irradiated by an ultraviolet ray carbon arc lamp for 80 hours is 2.0 or lower. <P>COPYRIGHT: (C)2003,JPO

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 for attaching a window, which is used by being attached to glass such as an automobile window or a building window.

[0002]

2. Description of the Related Art For the purpose of protecting privacy, designing, adjusting sunlight, and preventing glass from scattering, films attached to windows of automobiles and windows of buildings have transparency, light resistance,
A polyester film having excellent water resistance, heat resistance, chemical resistance, and mechanical strength is often used. We have already proposed in Japanese Patent No. 2699397 to use a composite film in which a dye is contained in the inner layer of a laminated polyester film having three or more layers, as a window-shielding polyester film having a light-shielding property.

By the way, these films are usually attached to the inner surface of glass in many cases, and in that case, a short portion of short-wave ultraviolet rays is blocked by passing through the glass and a sizing agent containing an ultraviolet absorber. To be done. However,
A film once attached to a window glass is often used semipermanently. Therefore, the film itself is required to have little change over time, but with the coloring materials that have been used for this purpose in the past, these cannot be completely prevented, and light resistance is insufficient, and discoloration / fading of the film is avoided. I couldn't do it. There is also a proposal to prevent discoloration and fading of the film by adding an ultraviolet absorber to a coloring material having insufficient light resistance, but these ultraviolet absorbers are generally expensive and Discoloration due to the light resistance of the material itself
It is desired to prevent fading.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a problem to be solved by the present invention is to discolor or discolor after long-term use without using an ultraviolet absorber or a radical absorber. An object of the present invention is to provide a light-shielding film for window attachment, which rarely does.

[0005]

As a result of intensive studies to solve the above problems, the present inventor has found that a film having a specific structure can easily solve the above problems, and completes the present invention. Came to. That is, the gist of the present invention is a coextrusion laminated film comprising at least three layers of polyester, which contains a dye that is substantially soluble in polyester in the intermediate layer, and an ultraviolet absorber or a radical absorber in any layer. The present invention is a biaxially oriented polyester film for window sticking, characterized in that the color tone change ΔE ^* ab when the film is directly irradiated with an ultraviolet carbon arc lamp for 80 hours is 2.0 or less.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. The biaxially oriented polyester film of the present invention needs to be a film in which at least three or more polyester layers are laminated, and more specifically, all layers are melt-extruded together from an extrusion die, so-called It is a film extruded by an extrusion method. Further, the film needs to be not an unstretched state or a uniaxially stretched film, but a film that is stretched and oriented in the biaxial directions of the longitudinal direction and the transverse direction, and then heat-set. Such a laminated film has surface layers on both sides and an intermediate layer between them, but the intermediate layer itself may have a laminated structure.

When the polyester fill has a single-layer structure, a phenomenon (bleed-out) in which the added dye comes out to the film surface and a phenomenon in which it sublimes are liable to occur, which pollutes the film forming machine. Because
In many cases, the production itself cannot be performed, and even if it can be produced, the surface layer has effluents from the inside of the film due to bleed-out, which often adversely affects post-processing, which is not preferable. In the polyester film of the present invention, it is preferable that the polyester used for each laminated layer is obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol.

Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid,
Examples of the aliphatic glycol include ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol and the like. Typical polyesters include polyethylene terephthalate (PET), polyethylene-
2,6-naphthalenedicarboxylate (PEN) and the like are exemplified. Among these, PET is the most frequently used polyester because it has a good balance between physical properties and cost.

The polyester used in the present invention is 1 in total.
The copolymer containing the third component may be within 0 mol%, preferably within 5 mol%. Examples of the dicarboxylic acid component of the copolyester include one or two of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (for example, P-oxybenzoic acid). Examples of the glycol component include ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, and the like.
One or more kinds of neopentyl glycol and the like can be mentioned.

The biaxially oriented polyester film for window sticking of the present invention needs to contain a dye in the intermediate layer of its laminated structure, and the content of the dye is 0.01 to 10.0.
It is preferable to select from the range of weight%. Further, as a result, the visible light transmittance of the entire film is preferably in the range of 3 to 75%, more preferably 5 to 50%. The dye used for this needs to be substantially soluble in the polyester. The term “substantially dissolved” as used herein means that when the polyester is kneaded in a molten state, aggregates and the like are uniformly mixed without leaving, whereby the film haze described below is 6.0% or less, preferably Is 4.
It means 5% or less, and more preferably 3.0% or less.

Further, these dyes are used in the visible light region (38
It is preferable to have absorption in the range of 0 to 780 nm), and polyesters that decompose little at the molding temperature of polyester are preferable. Examples of such dyes preferably include anthraquinone-based, perinone-based, perylene-based, azomethine-based, and heterocyclic dyes in terms of chemical structure, and oil-soluble dyes are preferable in terms of dyeing prescription. Further, even those which are generally classified as pigments can be used as dyes in the present invention as long as they are dissolved in the molten polyester as described above. Examples thereof include phthalocyanine-based complex dyes with copper, cobalt, nickel, zinc, chromium and other metal ions. These dyes, for example, to tone gray or brown,
It is also possible to appropriately select and use a mixture of several kinds. However, even in this case, the total amount of these dyes in the polyester film intermediate layer is 0.01 to 10% by weight, preferably 0.
It is added so as to be in the range of 1 to 5.0% by weight.

The film of the present invention has a color tone change ΔE ^* ab of 2.0 or less, preferably 1.5 or less, when the film is directly irradiated with an ultraviolet carbon arc lamp for 80 hours.
More preferably, it is 1.0 or less. At this time, the irradiation of the ultraviolet carbon arc lamp was set so that the temperature of the black panel panel was 63 ° C., and the value was measured when the water was not sprayed, and the test is usually carried out in a fade meter. Under the irradiation conditions of the above-mentioned UV carbon arc lamp, when the film color change ΔE ^* ab after 80 hours exceeds 2.0, when the film is actually attached to a window glass and exposed to sunlight, The fading tends to be noticeable in a short period of time, which is not preferable. In order to satisfy the above-mentioned change in color tone, it is preferable to select, as the dye used in the present invention, a dye that is fast against ultraviolet rays. Whether or not a dye is robust to ultraviolet rays does not have a clear correlation with the chemical structure of the dye.For example, even if the dye has the same anthraquinone-based chemical structure, its basic skeleton In general, the fastness to ultraviolet rays greatly varies depending on the type, number and position of the substituents introduced into. Under such circumstances, DIARESIN 4G, which is a dye for plastics manufactured by Mitsubishi Chemical Corporation, can be exemplified as a dye having extremely good ultraviolet resistance.

The biaxially oriented polyester film for window attachment of the present invention does not contain a light stabilizer such as an ultraviolet absorber or a radical absorber in all layers of the laminated polyester. The ultraviolet absorber referred to in the present invention means a benzotriazole derivative, a benzophenone derivative, 1,3,3
Refers to organic UV absorbers such as 5-triazine derivatives, cyanoacrylic acid ester derivatives, salicylate ester derivatives, and radical absorbers are hindered amine light stabilizers, especially those composed of a 6-membered piperidine ring. Refers to an organic compound.

The haze of the biaxially oriented polyester film for window sticking of the present invention is preferably 6.0% or less, more preferably 4.5% or less, and particularly preferably 3.0% or less. When the film haze is more than 6.0%, it is not preferable because the film tends to be turbid and the transparency is impaired when the film is attached to a window glass.

In the present invention, the method of adding the dye to the polyester may be a method of adding these in the form of powder, paste, liquid or the like when the film is melt-molded. Considering ease of use, it is preferable to prepare dye master batches in advance and add these master batches while diluting with a clear resin during melt molding of the film. Further, it is preferable to use a twin-screw extruder in order to carry out melt-molding of these while kneading the polyester with good dispersion. The polyester film of the present invention may contain fine particles having a particle size and an addition amount sufficient to form fine projections on both surface layers of the laminated structure in order to secure the surface slipperiness.

The fine particles usable for this purpose are, for example,
One or more of silicon oxide, calcium carbonate, kaolin, crosslinked organic polymer fine powder having an average particle diameter of 0.02 to 3.0 μm can be used, and the addition amount is 0.00.
1 to 0.5% by weight, preferably 0.01 to 0.1% by weight
It is preferable to appropriately select from the above because the film haze is not increased and the necessary minimum slip property can be secured. As a result, the average surface roughness Ra of the film is
The thickness is preferably in the range of 0.005 to 0.050 μm. Further, regarding the laminated thickness configuration of the surface layer and the intermediate layer,
In order to suppress turbidity of the entire film (film haze), it is preferable that the surface layer to which the fine particles are added be as thin as possible. On the other hand, in order to prevent the dye existing in the intermediate layer from bleeding out, it is preferable that the surface layer is rather thick. Taking these into consideration, the surface layer thickness is preferably in the range of 0.5 to 4.0 μm regardless of the thickness of the entire film.

Next, the method for producing the laminated polyester film of the present invention will be specifically described, but the film of the present invention is not limited to the following production examples. First, using the above-mentioned polyester raw material, using a plurality of extruders, a multi-layer multi-manifold die or a feed block, laminating the respective polyesters, extruding a multi-layer molten sheet from a die, and cooling. It is cooled and solidified by a roll to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is preferable to increase the adhesion between the sheet and the rotary cooling drum, and it is preferable to adopt the electrostatic application adhesion method and / or the liquid application adhesion method.

Then, the obtained unstretched film is stretched biaxially to be biaxially oriented. That is, the unstretched sheet is stretched in the machine direction by a roll stretching machine. The stretching temperature is usually 70 to 120 ° C, preferably 80 to 110 ° C.
And the draw ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Then, stretching is performed in the lateral direction. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 11
It is 5 ° C., and the draw ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. And, continuously, 170-2
Heat treatment is carried out at a temperature of 50 ° C. under tension or under relaxation within 30% to obtain a biaxially stretched film. In the above stretching, a method of stretching to a predetermined stretching ratio by one stretching operation, or a method of dividing the stretching into two or more stages to obtain a predetermined stretching ratio can be used. Even in that case, it is preferable that the stretching ratios in the two directions be finally within the above ranges. It is also possible to carry out simultaneous longitudinal and transverse biaxial stretching of the unstretched sheet so that the area ratio becomes 10 to 40 times. Further, if necessary, it may be stretched again in the machine direction and / or the transverse direction before or after the heat treatment.

The surface of the above-mentioned film can be coated if necessary. For example, improved adhesion,
For the purpose of imparting antistatic property and anti-scratch property of the surface, in-line coating, off-line coating, or a combination of both can be performed. Especially in the case of in-line coating, in the above film manufacturing method, after the longitudinal stretching is completed, a coating solution containing water as a medium is mainly applied, followed by drying, preheating and transverse stretching in a tenter, and further heat setting. A series of processes for doing can be used.

Further, the biaxially oriented polyester film for attaching a window of the present invention may be provided with a known hard coat layer on the surface opposite to the surface attached to the window glass for the purpose of preventing scratches and the like. The hard coat layer is preferably made of a resin containing a thermosetting or UV curable polyacrylic resin having both transparency and scratch resistance. To bond the film thus obtained to a window glass or the like, a method of bonding the film and the glass via an adhesive or an adhesive may be used. Also,
In that case, a publicly known ultraviolet absorber can be compounded and used together with the adhesive or the adhesive to be used, or an infrared absorber can be added in a known amount. A known plastic film that has been subjected to a known release treatment can be used as the so-called separator film for this pressure-sensitive adhesive or adhesive.

[0021]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples and comparative examples, “part” means “part by weight”. The measuring method used in the present invention is as follows.

(1) Visible light transmittance Spectrophotometer SE-2000 (manufactured by Nippon Denshoku Co., Ltd.) was used to measure the light transmittance of each wavelength with a D65 light source.
The visible light transmittance was calculated according to S 3107; 1998.

(2) Turbidity of film (film haze) JIS K 7136; 2000 (ISO 1478)
2; 1999), the turbidity (haze) of the film was measured using a turbidimeter NDH2000 (manufactured by Nippon Denshoku Co., Ltd.).

(3) Surface Roughness (Ra) of Film The surface roughness is defined as the center line average roughness Ra (μm).
It was determined as follows using a surface roughness measuring device (SE-3F) manufactured by Kosaka Laboratory Ltd. That is, a portion having a reference length L (2.5 cm) is cut from the film cross-section curve in the direction of the center line, and the roughness curve Y = f with the center line of the cut portion as the X axis and the longitudinal magnification direction as the Y axis. When represented by (X), the value given by the following equation is expressed in μm. The center line average roughness was represented by the average value of the center line roughness of the extracted portion obtained from 10 cross-section curves obtained from the sample film surface. The tip radius of the stylus is 2 μm,
The load was 30 mg and the cutoff value was 0.08 mm. Ra = (1 / L) ∫ L 0 | f (X) | dX

(4) Evaluation of discoloration / fading of film (color tone change ΔE ^* ab) The film was attached to a glass plate and placed so that the film surface was directly exposed to ultraviolet light, and an ultraviolet carbon arc lamp was used in a fade meter. And conducted a promotion test. At this time, long-life carbon was used as the carbon arc lamp, the discharge voltage and current were 135 V and 16 A, and the temperature indicated by the black panel thermometer was 63 ± 3 ° C. Irradiation was carried out for 80 hours without spraying water. Evaluation of discoloration / fading of the film is performed by the color tone (L ^* , a ^* ,
b ^* ) was measured before and after irradiation with ultraviolet rays for comparison.
To measure the color tone, use the spectroscopic colorimeter S used in (1) above.
E-2000 was used. For the change in color tone, the color difference ΔE ^* ab was calculated using the following formula. ΔE ^* ab = ((ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ) ^1/2

The method for producing the polyester raw materials used in the following examples and comparative examples is as follows. <Polyester A> 100 parts of dimethyl terephthalate,
60 parts ethylene glycol and 4 magnesium acetate
Taking 0.09 parts of water salt into a reactor, heating and heating to distill off methanol to carry out a transesterification reaction, and it takes 4 hours from the start of the reaction to raise the temperature to 230 ° C. to substantially transesterify Finished. Then, after adding 0.04 part of ethyl acid phosphate and 0.04 part of antimony trioxide, the temperature was 280 ° C. and the pressure was 15 m in 100 minutes.
mHg, the pressure is gradually reduced thereafter, and finally 0.3
It was mmHg. After 4 hours, the pressure in the system was returned to normal pressure to obtain polyester A containing substantially no fine particles. The intrinsic viscosity of this polyester was 0.70.

<Polyester B> 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, heated and heated to distill off methanol to carry out a transesterification reaction. It took 4 hours from the start to raise the temperature to 230 ° C,
The transesterification reaction was substantially completed. Then, ethylene glycol slurry containing 2.0 parts of silica particles having an average particle size of 1.5 μm was added to the reaction system, and then 0.04 part of ethyl acid phosphate and 0.04 part of antimony trioxide were added, The temperature is 280 ° C in 100 minutes,
The pressure was set to 15 mmHg, and thereafter, the pressure was gradually reduced to finally 0.3 mmHg. After 4 hours, the system was returned to normal pressure to obtain polyester B. The silica particle content of the obtained polyester B was 1.0% by weight. The intrinsic viscosity of this polyester was 0.70.

<Polyester C> Polyester A was supplied to a twin-screw extruder with a vent, and 2.5% by weight of DIARESIN RED HS manufactured by Mitsubishi Chemical Co., Ltd. and Blue 4G 6.0 manufactured by Mitsubishi Chemical Corporation.
Wt% and the same yellow F 1.5 wt% were mixed and added, and melt-kneaded to form chips to prepare a dye masterbatch Polyester C. <Polyester D> Polyester A was supplied to a twin-screw extruder with a vent, and Mitsubishi Chemical Corp.'s dialect resin red H
2.5% by weight of S, 6.0% by weight of blue H3G, and 1.5% by weight of yellow F are mixed and added, and melt-kneaded to form chips.
Dye Masterbatch Polyester D was prepared.

Example 1 Chips of polyesters A and C were put in a middle layer extruder as a middle layer resin at a ratio of 92.0: 8.0. Separately, each polyester A, B chip 9
The resin for the surface layer was charged into the extruder for the surface layer at a ratio of 3: 7. Each extruder is a bi-directional extruder with vents, and the resin is 290 without drying.
Extrusion was carried out at a melting temperature of ° C, after which the molten polymer was combined and laminated in a feedblock. Then, it was cooled and solidified on a cooling roll whose surface temperature was set to 40 ° C. by using the electrostatic application adhesion method to obtain a laminated unstretched sheet having a three-layer structure.
The obtained sheet was stretched 3.5 times in the machine direction at 85 ° C.
Then, the film was introduced into a tenter, stretched 3.7 times in the transverse direction at 105 ° C, heat-set at 230 ° C, and further subjected to a 5% relaxation treatment at 200 ° C in the width direction to give a biaxially oriented film. Created. The thickness of each layer of this film is 2 /
The structure was 21/2 μm, and the total thickness was 25 μm. The visible light transmittance of this film was about 30%, the film haze was 2.0%, and the surface roughness was 0.015 μm on both sides.
It was m. Also, the color difference ΔE ^* ab due to irradiation with an ultraviolet carbon arc lamp for 80 hours in a fade meter
The value was as good as 0.95. Example 2 In Example 1, chips of polyesters A, C, and D were charged as a resin for the intermediate layer into the extruder for the intermediate layer at a ratio of 92.0: 5.0: 3.0. Separately from this, chips of polyesters A and B were introduced into a surface layer extruder as a surface layer resin at a ratio of 93: 7. After that, film formation was performed in exactly the same manner as in Example 1 to prepare a biaxially oriented film.
The thickness of each layer of this film was 2/21/2 μm, and the total thickness was 25 μm. The visible light transmittance of this film is about 30%, and the film haze is 2.0.
%, And the surface roughness was 0.015 μm on both sides. In addition, the color difference ΔE ^* ab value due to irradiation with an ultraviolet carbon arc lamp for 80 hours in a fade meter was 1.90, which was inferior to Example 1 but was within a practically acceptable range. Comparative Example 1 In Example 1, chips of polyesters A and D were charged as a resin for the intermediate layer into the extruder for the intermediate layer at a ratio of 92.0: 8.0. Separately from this, chips of polyesters A and B were introduced into a surface layer extruder as a surface layer resin at a ratio of 93: 7. After that, film formation was performed in exactly the same manner as in Example 1 to prepare a biaxially oriented film. The thickness of each layer of this film is 2/21/2 μm, and the total thickness is 2
It was 5 μm. The visible light transmittance of this film is about 3
The film haze was 2.0%, and the surface roughness was 0.015 μm on both sides. In addition, the color difference ΔE ^* ab value due to irradiation with an ultraviolet carbon arc lamp for 80 hours in a fade meter was inferior to 3.25.

[0030]

Industrial Applicability According to the present invention described above, it is possible to provide a window-adhering polyester film in which discoloration / fading of the entire film due to sunlight or fluorescent light is suppressed, and its industrial value is high.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29L 7:00 B29L 7:00 9:00 9:00 F term (reference) 4F100 AK25D AK41A AK41B AK41C AK42 BA03 BA04 BA06 BA07 BA10A BA10C BA10D BA15 BA16 CA13B CC00D EH20 EJ38 GB07 GB32 JK12D JN01 JN28 YY00 4F210 AA24 AB12 AG01 AG03 AH48 QA02 QA03 QC06 QG01 QG15 QG18 QW07 QW12

Claims (3)

[Claims] 1. A coextrusion laminated film comprising at least three layers of polyester, wherein a dye which is substantially soluble in polyester is contained in the intermediate layer, and any layer contains an ultraviolet absorber or a radical absorber. , A biaxially oriented polyester film for window sticking, which has a color tone change ΔE ^* ab of 2.0 or less when the film is directly irradiated with an ultraviolet carbon arc lamp for 80 hours. 2. The biaxially oriented polyester film for window sticking according to claim 1, wherein the haze of the entire film is 6.0% or less and the visible light transmittance of the film is 3 to 75%. 3. A composite polyester film for window attachment, comprising a hard coat layer containing a polyacrylic resin on one surface of the biaxially oriented polyester film for window attachment according to claim 1 or 2.