JP4233396B2 - Biaxially oriented laminated polyester film for window pasting - Google Patents

Description

【００５０】
【表２】

【００５１】
【発明の効果】
本発明によれば、染料の昇華等によって生産機を汚染することがなく、曲面ガラスなどへの施工性に優れると共に透明性に優れた窓貼り用二軸配向積層ポリエステルフィルムを提供することができ、その工業的価値は高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a biaxially oriented laminated polyester film suitable for window pasting, for example, used by pasting on glass such as automobile windows and building windows. More specifically, the present invention relates to a biaxially oriented laminated polyester film suitable for window pasting that suppresses the precipitation of dye on the film surface and is excellent in workability and design on a glass surface having a curved surface. .
[0002]
[Prior art]
Transparency, light resistance, water resistance, heat resistance, chemical resistance for films to be bonded to automobile windows and building windows for the purpose of privacy protection, design, solar control, glass scattering prevention, etc. A polyester film having excellent mechanical strength is often used. As a polyester film for window pasting which has light-shielding property, using the composite film which made the inner layer of the laminated polyester film of three or more layers contain dye is proposed (patent documents 1 and 2).
When pasting such a light-shielding film on a window or the like, it is easy to paste on a flat surface, but when pasted on a surface having a curved surface, wrinkles etc. are likely to enter, and the workability is insufficient. is there.
[Patent Document 1]
Japanese Patent No. 2699397 [Patent Document 2]
Japanese Patent Laid-Open No. 10-157040
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and the problem to be solved is a biaxial shaft suitable for window pasting that suppresses dye deposition on the film surface and is excellent in workability and design on curved surfaces. The object is to provide an oriented laminated polyester film.
[0004]
[Means for Solving the Problems]
As a result of intensive studies in view of the above circumstances, the present inventors have found that the above-mentioned problems can be solved to a high degree by making the shrinkage rate of a film having a specific laminated configuration into a specific range. It came to be completed.
[0005]
That is, the gist of the present invention is a film in which at least three layers of polyester are coextruded and laminated, and the outermost layer has a thickness of 0.5 to 5 with the inner layer being a layer containing a dye that is substantially soluble in polyester. The present invention resides in a biaxially oriented laminated polyester film for window pasting, characterized in that the following formulas (1) and (2) are satisfied simultaneously.
6.0 ≦ SMD ≦ 20.0 (1)
0.0 ≦ STD ≦ 10.0 (2)
(In the above formula, SMD represents the heat shrinkage rate (%) in the film longitudinal direction during heat treatment at 180 ° C. for 5 minutes, and STD represents the heat shrinkage rate (%) in the film transverse direction during heat treatment at 180 ° C. for 5 minutes)
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
The biaxially oriented laminated polyester film of the present invention needs to be a film in which at least three or more polyester layers are laminated. More specifically, all the layers are melt-extruded together from an extrusion die, so-called co-polymerization. It is a film extruded by an extrusion method. Further, the film is not an unstretched state or a uniaxially stretched film, but needs to be 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 a coextruded surface layer on both sides and a coextruded intermediate layer therebetween, but the coextruded intermediate layer itself may have a laminated structure.
[0007]
When the polyester fill has a single layer configuration, the phenomenon that the added dye swells on the film surface (bleed out) and the phenomenon that it sublimates easily occur, and this causes contamination of the film forming machine, In many cases, the production itself is not possible, and even if it can be produced, the surface layer contains springs from the inside of the film due to bleed-out, which is not preferable because it often adversely affects post-processing.
[0008]
The polyester used for each layer constituting the polyester film of the present invention is usually obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like. Among these, PET has a good balance between physical properties and cost, and is the most frequently used polyester.
[0009]
The polyester used in the present invention may be a copolymer containing a third component as long as it is within 10 mol%, preferably within 5 mol% in total. 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). The glycol component may be one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like.
[0010]
The biaxially oriented laminated polyester film of the present invention needs to contain a dye that substantially dissolves in the polyester in the inner layer (intermediate layer) of the laminated structure. The term “substantially dissolved” as used in the present invention means that, when kneaded in a molten state of polyester, it means that the agglomerates and the like are mixed uniformly without remaining, whereby the film haze described below is usually 6.0% or less. , Preferably 5.0% or less, more preferably 3.0% or less. The dye to be used preferably has an absorption in the visible light region (380 to 780 nm), and preferably has a low decomposition at the polyester molding temperature. Such dyes are preferably anthraquinone, perinone, perylene, azomethine, and heterocyclic dyes in terms of chemical structure, and dispersible dyes and oil-soluble dyes are suitable in terms of dyeing prescription. is there. Moreover, even if it is generally classified as a pigment, it can be used as a dye in the present invention as long as it is soluble in molten polyester as described above. Examples thereof include complex salt dyes with metal ions such as copper, cobalt, nickel, zinc and chromium such as phthalocyanine.
[0011]
The above-mentioned dyes are generally used by appropriately selecting and mixing several kinds thereof, for example, in order to adjust to gray or brown, and the content of these dyes in the polyester is usually It is preferable to select from the range of 0.01 to 10.0% by weight, preferably 0.05 to 5.0% by weight. Specifically, the visible light transmittance of the entire film is preferably in the range of 3 to 75%, more preferably 5 to 50%.
[0012]
In the biaxially oriented laminated polyester film for window pasting of the present invention, a known ultraviolet absorber or radical trapping agent can coexist in addition to the above-mentioned dye in the coextruded intermediate layer. However, depending on the additive, the film may become turbid, and in that case, it is not preferable to use the additive.
[0013]
The method of adding the dye and other additives used in the present invention to the polyester may be a method of adding these powders, pastes, or liquids when melt-molding the film. Considering the ease of switching, it is preferable to prepare a masterbatch such as a dye in advance and add the masterbatch while diluting with a clear resin during melt molding of the film. In addition, it is particularly preferable to use a twin screw extruder in order to carry out the melt molding while kneading the polyester with good dispersion.
[0014]
In order to ensure the slipperiness of the surface layer surface, the polyester film of the present invention can contain fine particles having a particle diameter and an addition amount sufficient to form fine protrusions on the coextruded surface layer on both sides. The fine particles that can be used for this purpose include, for example, one or more of silicon oxide, calcium carbonate, kaolin, crosslinked organic polymer fine powder having an average particle size of 0.02 to 5.0 μm, and added. The amount is appropriately selected from 0.001 to 0.5% by weight, preferably 0.01 to 0.1% by weight, and the minimum slipperiness can be ensured without increasing the film haze. It is preferable. The above conditions are preferably selected so that the average surface roughness (Ra) of the film surface is in the range of 0.005 to 0.050 μm.
[0015]
Furthermore, it is possible to add known additives such as an infrared absorber and an ultraviolet absorber to the polyester constituting the coextruded surface layer in an amount not exceeding the gist of the present invention.
[0016]
Regarding the laminated thickness structure of the coextruded surface layer and the inner layer, the coextruded surface layer to which fine particles are added is preferably as thin as possible in order to suppress turbidity (film haze) of the entire film. On the other hand, in order to prevent the dye and other additives present in the inner layer from bleeding out, the coextruded surface layer is preferably thicker. Considering these, in the laminated film of the present invention, the thickness of each outer layer is preferably 0.5 to 5.0 μm on one side regardless of the thickness of the entire film. Moreover, although the thickness of both surface layers may be the same or may differ, it is preferable that both are in said thickness range also in different cases.
[0017]
When the thickness of the outermost layer is less than 0.5 μm, the dye sublimation in the intermediate layer may not be sufficiently suppressed during the heat setting treatment during the film forming process. Moreover, when the thickness of the outermost layer exceeds 5 μm, the intermediate layer becomes thin, and the content of the dye necessary for obtaining a highly light-shielding film tends to be excessively increased. The resulting turbidity may increase the film haze, decrease the intrinsic viscosity of the polyester, lose the properties of the polyester itself, or cause unevenness in the thickness of the intermediate layer, which may cause color spots.
[0018]
The laminated film of the present invention has a heat shrinkage ratio (SMD) in the longitudinal direction of the film of 6.0 to 20.0% when heat-treated at 180 ° C. for 5 minutes in order to improve the workability when pasted on a curved glass of an automobile. The film has a heat shrinkage (STD) in the transverse direction of 0.0 to 10.0% or less. The SMD is preferably in the range of 6.0 to 15%, and the STD is preferably in the range of 1.0 to 10.0%. When the SMD is less than 6.0% and the STD is less than 0.0% (minus = expanded side), wrinkles are generated when the laminated film is applied to the curved glass of the automobile, which is not preferable. Moreover, when SMD exceeds 20.0% or STD exceeds 15%, wrinkles are generated during hard coat processing, which is not preferable.
[0019]
The polyester film of the present invention has a known heat-curing or UV-curing property mainly composed of an acrylic acid derivative or a methacrylic acid derivative on the exposed surface for the purpose of preventing scratches on the exposed surface when attached to a window glass. The hard coat layer can be provided. This hard coat layer is preferably not provided by in-line coating, but as a post-processing of a biaxially oriented laminated polyester film that has been subjected to orientation crystallization, usually by application and drying using an organic solvent. The application can be performed using an apparatus such as a reverse gravure coater, a gravure coater, a rod coater, or an air doctor coater.
[0020]
Since the hard coat layer becomes an exposed surface when the film is attached to the window glass, the surface hardness of the hard coat layer may be H or more in pencil hardness in order to prevent the occurrence of scratches easily. preferable. To maintain a surface hardness of H or higher in pencil hardness, a thicker film is better. However, the hard coat agent shrinks when cured, and the film curls due to this shrinkage, thus preventing curling. The coat thickness is preferably thin. In order to satisfy these conflicting characteristics at the same time, it is preferable to set the thickness (dry thickness) of the hard coat layer in the range of 0.5 to 5.0 μm.
[0021]
The film of the present invention is coated with a known pressure-sensitive adhesive or a known adhesive to bond the film to a window glass or the like. When applying this pressure-sensitive adhesive or adhesive to the film, an organic solvent is usually applied as a post-processing on the biaxially oriented laminated polyester film in which orientation crystallization has been completed in the same manner as when applying the hard coat layer. Used by coating and drying. The pressure-sensitive adhesive or adhesive can be used in combination with a known ultraviolet absorber, or an infrared absorber can be added in a known amount. For this pressure-sensitive adhesive or adhesive, for example, a known plastic film that has been subjected to a release treatment with a silicone coating film can be used as a so-called separator film.
[0022]
Next, although the manufacturing method of the laminated polyester film of this invention is demonstrated concretely, the film of this invention is not limited to the following manufacture examples at all.
First, using the polyester raw material described above, using multiple extruders, multiple layers of multi-manifold dies or feed blocks, laminating each polyester and extruding multiple layers of molten sheet from the die, cooling An unstretched sheet is obtained by cooling and solidifying with a roll. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and it is preferable to employ an electrostatic application adhesion method and / or a liquid application adhesion method.
[0023]
Next, the obtained unstretched film is stretched biaxially and biaxially oriented. That is, the unstretched sheet is stretched in the longitudinal direction by a roll stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, stretching is performed in the transverse direction. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 115 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or relaxation within 30% to obtain a biaxially stretched film.
[0024]
In the above-described stretching, in addition to a method of stretching to a predetermined ratio by a single stretching operation, a method of distributing the stretching into two or more stages to obtain a predetermined stretching ratio can also be used. Even in that case, it is preferable that the stretching ratios in the two directions are finally in the above ranges. Furthermore, it may be stretched again in the longitudinal and / or transverse direction before or after performing the heat treatment, if necessary.
[0025]
In the present invention, as described above, it is necessary to have an antistatic coating layer on at least one surface of the film, and particularly when the antistatic coating layer is applied by in-line coating, the longitudinal stretching is completed by the above process. At this time, it is preferable to apply a coating solution mainly containing water to the surface of the film, then dry, preheat, and transversely stretch in the tenter, and further heat set. Moreover, the application | coating method used at this time can apply | coat using apparatuses, such as a reverse gravure coater, a gravure coater, a rod coater, and an air doctor coater.
[0026]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. In the examples and comparative examples, “parts” means “parts by weight”. The measuring method used in the present invention is as follows.
[0027]
(1) Viscosity (IV)
1 g of polymer was dissolved in 100 ml of a mixed solvent of phenol / tetrachloroethane = 1/1 (weight ratio) and measured at 30 ° C.
[0028]
(2) Average particle size Centrifugal sedimentation type particle size distribution measuring device (“SA-CP3 type” manufactured by Shimadzu Corporation) was used to measure the particle size by the sedimentation method based on Stokes' resistance law. The value of 50% of integration (volume basis) in the equivalent spherical distribution of particles obtained by measurement was defined as the average particle size.
[0029]
(3) Thickness of each film layer A film piece was fixed with an epoxy resin, cut with a microtome, and a cross section of the film was observed with a transmission electron micrograph. The interface is observed by two contrasts that are almost parallel to the film surface. The distance between the two interfaces and the film surface was measured from 10 photographs, and the average value was defined as the laminated thickness.
[0030]
(4) Turbidity of film (film haze)
According to JIS-K7105, the turbidity (haze) of the film was measured using a turbidimeter NDH300A (manufactured by Nippon Denshoku Co., Ltd.).
[0031]
(5) Visible light transmittance spectral colorimeter SE-2000 (manufactured by Nippon Denshoku Co., Ltd.) was used to measure the light transmittance of each wavelength with a D65 light source, and the visible light transmittance was calculated according to JIS S3107. did.
[0032]
(6) Thermal contraction rate (SMD, STD)
Using a hot air circulating furnace (manufactured by Taibai Seisakusho), heat-treated a film of 25 μm thickness in a tension-free state for 5 minutes in an atmosphere at 180 ° C. before and after heat treatment in the longitudinal direction (SMD) and transverse direction (STD) Was measured by the following formula, and expressed as an average value for five samples.
Thermal contraction rate (%) = (L0−L1) × 100 / L0
(In the above formula, L0 represents the sample length (mm) before heat treatment, and L1 represents the sample length (mm) after heat treatment.) When L0 is smaller than L1 (in the case of expansion),-( (Minus).
[0033]
(7) Workability The state of wrinkles and surrounding gaps when a film was applied to the curved glass of an automobile was observed, and the workability was evaluated according to the following criteria.
○: When there is no wrinkle and the surrounding gap is uniform ×: When wrinkle is found or the surrounding gap is uneven [0034]
(8) When the tenter-contaminated film was formed, the tenter of the film-forming apparatus was observed, and the tenter contamination with the dye blended in the film was evaluated according to the following criteria.
◯: When contamination by dye is not observed Δ: When contamination by dye is slightly observed, but there is no problem in practical use ×: When contamination by dye is severe and hinders film formation [0035]
(9) Processability of hard coat (HC) In the step of forming a hard coat layer on the surface of the film, the film state during processing was observed, and the processability of the hard coat was evaluated according to the following criteria.
○: When a good hard coat film is obtained without wrinkling of the film. Δ: When the film is wrinkled but a hard coat film having no practical problem is obtained. ×: The film is wrinkled and hard as a product. When a coated film cannot be obtained [0036]
The manufacturing method of the polyester raw material used in the following examples and comparative examples is as follows.
<Polyester A> Diluted PET
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol, and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, and the temperature is raised while heating and methanol is distilled off. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, 0.04 part of ethyl acid phosphate and 0.04 part of antimony trioxide were added, and then the temperature was 280 ° C. and the pressure was 15 mmHg in 100 minutes. The pressure was gradually reduced thereafter, and finally 0.3 mmHg It was. After 4 hours, the system was returned to normal pressure to obtain polyester A substantially free of fine particles. The intrinsic viscosity of this polyester was 0.70.
[0037]
<Polyester B> Particle (1.4 μm) containing PET
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol, and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, and the temperature is raised while heating and methanol is distilled off. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, an ethylene glycol slurry containing 1.0 part of silica particles having an average particle size of 1.4 μm was added to the reaction system, and 0.04 part of ethyl acid phosphate and 0.04 part of antimony trioxide were further added. In 100 minutes, the temperature was 280 ° C. and the pressure was 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 resulting polyester B had a silica particle content of 1.0% by weight. The intrinsic viscosity of this polyester was 0.70.
[0038]
<Polyester C> MB containing 10% dye
Polyester A was subjected to a vented twin-screw extruder, and each concentration of Dialresin Red HS 3.0 wt%, Blue H3G 5.5 wt%, and Yellow F 1.5 wt% manufactured by Mitsubishi Chemical Corporation The resulting mixture was mixed and added, melt-kneaded to form chips, and polyester C as a dye master batch was prepared.
[0039]
<Production of polyester D> Particle (2.6 μm) -containing PET
In the production of polyester B, polyester D was obtained in the same manner as for polyester B, except that the silica particles having an average particle size of 1.4 μm were changed to silica particles having an average particle size of 2.6 μm. The resulting polyester D had a silica particle content of 1.0% by weight. The intrinsic viscosity of this polyester was 0.70.
[0040]
Example 1
<Manufacture of polyester film>
Each chip of polyester A and C was charged into the intermediate layer extruder at a ratio of 92: 8 as an intermediate layer resin. Apart from this, each chip | tip of polyester A and B was thrown into the extruder for surface layers as a resin for surface layers in the ratio of 93: 7. Each of the extruders was a bi-directional extruder with a vent, and the resin was extruded at a melting temperature of 290 ° C. without drying, and then the molten polymers were merged in a feed block and laminated. Thereafter, it was cooled and solidified on a cooling roll whose surface temperature was set to 40 ° C. by using an electrostatic application adhesion method to obtain a three-layer laminated unstretched sheet. The obtained sheet was stretched 3.5 times in the longitudinal direction at 83 ° C. Next, the film was guided to a tenter, dried and preheated at 93 ° C., stretched 4.0 times in the transverse direction, and heat fixed at 200 ° C. Further, a 5% relaxation treatment was performed in the width direction, and after cooling, the film was wound up to prepare a roll of a biaxially oriented film. The thickness of each layer of this film was 2/21/2 μm, and the total thickness was 25 μm.
[0041]
<Manufacture of hard coat layer>
Set the above film roll on a coater, apply a hard coat agent having the following composition with a # 20 bar, dry it at 90 ° C. for 1 minute and remove it, then use a high pressure mercury lamp to output 120 w / cm, irradiation distance It was dried under conditions of 15 cm and a moving speed of 10 m / min to form a 2 μm hard coat layer.
Hard coat composition:
Acrylic resin ("Seika Beam EXY-26 (S)" manufactured by Dainichi Seika Kogyo Co., Ltd.) 30 parts by weight: methyl ethyl ketone 35 parts by weight: toluene 35 parts by weight
Example 2
In the production of the polyester film of Example 1, the film of Example 2 was produced in the same manner as in Example 1 except that the relaxation rate in the width direction was changed to 7%.
[0043]
Example 3
In the production of the polyester film of Example 1, the film of Example 3 was produced in the same manner as in Example 1 except that the heat setting temperature was changed to 185 ° C.
[0044]
Example 4
In the production of the polyester film of Example 1, the film of Example 4 was prepared in the same manner as in Example 1 except that each chip of polyester A and D was changed to a ratio of 70:30 as the resin for the surface layer.
[0045]
Example 5
A film of Example 5 was produced in the same manner as in Example 1 except that the thickness of each layer was changed to 0.3 μm / 21 μm / 0.3 μm in Example 1.
[0046]
Comparative Example 1
In the production of the polyester film of Example 1, a film of Comparative Example 1 was prepared in the same manner as in Example 1 except that the heat setting temperature was changed to 225 ° C.
[0047]
Comparative Example 2
In the production of the polyester film of Example 1, a film of Comparative Example 2 was prepared in the same manner as in Example 1 except that the heat setting temperature was changed to 175 ° C.
[0048]
Comparative Examples 3-6
The film was obtained by changing as described in Table 2 below.
The obtained results are summarized in Tables 1 and 2 below.
[0049]
[Table 1]

[0050]
[Table 2]

[0051]
【The invention's effect】
According to the present invention, it is possible to provide a biaxially oriented laminated polyester film for window pasting that does not contaminate the production machine due to dye sublimation or the like, is excellent in workability to curved glass, etc., and has excellent transparency. , Its industrial value is high.

Claims (1)

A layer containing a dye substantially dissolved in the polyester and the inner layer is a film of polyester of at least three layers are coextruded laminated, the outermost layer of a thickness of 0.5 to 5.0 .mu.m, the following formula ( A biaxially oriented laminated polyester film for window pasting characterized by satisfying 1) and (2) simultaneously.
6.0 ≦ SMD ≦ 20.0 (1)
0.0 ≦ STD ≦ 10.0 (2)
(In the above formula, SMD represents the heat shrinkage rate (%) in the film longitudinal direction during heat treatment at 180 ° C. for 5 minutes, and STD represents the heat shrinkage rate (%) in the film transverse direction during heat treatment at 180 ° C. for 5 minutes)