JP2013199077A - Easily adhesive polyester film, laminate using the same, and method of producing the laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film excellent in adhesion with a polyfluorine film.SOLUTION: In an easily adhesive polyester film, an easily adhesive coating layer is arranged on at least one surface. The easily adhesive coating layer includes 70-95 wt.% of an acrylic resin. The easily adhesive coating layer is applied before drawing of an oriented polyester film is finished. In the easily adhesive coating layer, a fluorine-containing resin film is used to be laminated directly. A laminate directly laminated with the fluorine-containing resin film is also provided.

Description

  The present invention is an easy-adhesive polyester film having an easy-adhesive coating film layer formed on at least one surface thereof, and a laminate in which a fluorine-containing resin film is directly laminated thereon. Adhesive polyester film and laminate.

In recent years, polyvinyl chloride-based, polymethacrylic acid ester-based, and polyfluorinated-based films have been used together with various paints as surface protective films for indoor and exterior members. These protective films are used for interiors such as wallpaper, elevators and vehicles, as well as roofing materials, wall materials, gutters, garage roofs, solariums, agricultural materials, signboards, signs, labels, and window glass. A wide variety of weather resistance.
Protective films based on the above three types of materials are used for various purposes depending on their price, characteristics, etc., but the former is less expensive in terms of price, while the latter is more weatherproof in terms of characteristics. Is excellent.

  However, among these three types of material films, the polyfluorinated film is much better than the other two in terms of contamination resistance and strength in addition to the above weather resistance, but a substrate such as a polyester film. It has the disadvantage that it is inferior in adhesiveness. Specifically, a polyvinyl chloride-based film and a polymethacrylic acid ester-based film can employ a thermal bonding method depending on the application. However, in a polyfluorinated film, Patent Document 1 (Japanese Patent Laid-Open No. 2008-28294) and Patent Document 2 ( As described in JP 2009-246360 A, an adhesive system using an adhesive is used. For this reason, a separate manufacturing process for forming the adhesive layer is required, which is expensive in price and limited in its use. Therefore, there is a strong demand for improved adhesiveness.

  Therefore, in Patent Document 3 (Japanese Patent Application Laid-Open No. 8-267675), referred to as an extrusion laminating method, a mixture of a mixture layer of a vinylidene fluoride resin or a methacrylate ester resin and a methacrylate ester resin or a vinylidene fluoride resin. A method is described in which the layers are pressure bonded with heat or adhesive. However, the problem of poor adhesion to a substrate such as polyester film has not been solved, and it is disadvantageous compared to the previous method in terms of process and cost, and in the case of a thinner film, adhesion is technically difficult. .

JP 2008-28294 A JP 2009-246360 A JP-A-8-267675

  An object of the present invention is to solve the problems of the prior art and provide a polyester film excellent in adhesion to a polyfluorinated film and a laminate excellent in adhesion using the polyester film.

As a result of diligent research to solve the above problems, the present invention has been found to be achieved by providing a specific film on a polyester film, and has reached the present invention.
Thus, according to the present invention, an easy-adhesion polyester film provided with an easy-adhesion coating film layer on at least one surface, the easy-adhesion coating film layer contains an acrylic resin in a range of 70 to 95 wt%, and is easy. An easy-adhesive polyester film that is applied before the stretching of the adhesive polyester film is completed and a fluorine-containing resin film is directly laminated on the easy-adhesive coating film layer is provided.

  Further, according to the present invention, there is also provided an easy-adhesive polyester comprising at least one of the easy-adhesive coating film layer containing an epoxy-based crosslinking agent in a range of 1 to 5 wt% based on the mass thereof. There is also provided a laminate comprising the easily adhesive polyester film of the present invention and a fluorine-containing resin film directly laminated on the surface of the easily adhesive coating layer.

  In addition, the fluorine-containing resin film contains a fluorine resin as a main component, and contains acrylic resin in a range of 25 to 75 wt% based on the mass of the fluorine-containing resin film, and is used for a solar cell back surface protective film. A laminate comprising at least one of the above is also provided.

  In addition, after applying a coating liquid containing acrylic resin in a range of 70 to 95 wt% on at least one surface of the polyester film before completion of the stretching treatment, a step of performing a stretching treatment to form an easily adhesive polyester film; There is also provided a method for producing a laminate in which a fluorine-containing resin film is formed on the easy-adhesion coating film layer of the obtained easy-adhesion polyester film.

  ADVANTAGE OF THE INVENTION According to this invention, the easily adhesive polyester film excellent in adhesiveness with a polyfluorine-type film can be provided, and also it becomes adhesiveness, laminating | stacking a polyfluorine-type film and an easily-adhesive polyester film directly. An excellent laminate can be provided.

Hereinafter, the present invention will be described in detail.
[polyester]
An aromatic polyester can be used as the polyester constituting the easily adhesive polyester film of the present invention. For example, an aromatic dicarboxylic acid component such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, and ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, An aromatic polyester composed of a diol component such as 1,6-hexanediol may be used. In particular, polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are preferable. The polyester may be a copolyester.

  The polyester may contain fine particles as a lubricant as necessary in order to improve the film winding property during film formation, the film transportability in the back surface protective film processing step for solar cells, and the like. As such fine particles, either inorganic fine particles or organic fine particles may be used. Examples of the inorganic fine particles include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, and zinc oxide. Examples of the organic fine particles include crosslinked acrylic resin particles, crosslinked polystyrene resin particles, urea resin particles, melamine resin particles, and crosslinked silicone resin particles.

  In addition to polyester, other resins such as colorants, antistatic agents, antioxidants, lubricants, catalysts, polyethylene, polypropylene, ethylene-propylene-polymers, olefinic ionomers, and other films such as mechanical strength You may make it contain arbitrarily in the range which does not impair a characteristic. In particular, when used as a solar cell back surface protective film, a dye or a pigment may be contained in order to improve the surface reflectance or to improve the design, in order to color white, black, or other colors.

[Ultraviolet absorber]
The easily adhesive polyester film of the present invention may contain an ultraviolet absorber in order to improve the weather resistance of the film. As this ultraviolet absorber, 2,2′-p-phenylenebis (3,1-benzoxazin-4-one), 2,2 ′-(4,4′-diphenylene) bis (3,1-benzoxazine) -4-one) and 2,2 ′-(2,6-naphthylene) bis (3,1-benzoxazin-4-one).

When the ultraviolet absorber is contained, the content thereof is preferably 0.1 to 5% by weight, more preferably 0.2 to 3% by weight per 100% by weight of the total of the polyester and the ultraviolet absorber. If it is less than 0.1%, the effect of preventing UV deterioration is small.
The method for adding the ultraviolet absorber to the polyester is not particularly limited, and examples thereof include a polyester polymerization step, kneading into a polymer in a melting step before film formation, and impregnation into a biaxially stretched film. In particular, kneading into the polymer in the melting step before film formation is also preferred in order to prevent a decrease in the degree of polymerization of the polyester. At that time, the kneading of the ultraviolet absorber can be performed by a direct addition method of a compound powder, a master batch method or the like.

[Easily adhesive coating layer]
The easy-adhesive polyester film of the present invention is formed on at least one surface by coating an easy-adhesive coating film layer containing acrylic resin in a range of 70 to 95 wt% before the stretching of the easy-adhesive polyester film is completed. .
The ratio of the acrylic resin in the easy-adhesive coating layer is in the range of 70 to 95% by mass based on the mass of the easy-adhesive coating layer. If it is less than the lower limit, the coating layer becomes fragile and the adhesion with PVDF may not be maintained. If the upper limit is exceeded, the amount of the crosslinking agent and surfactant is relatively decreased, so that the polyfluorine type Adhesiveness with the film may decrease.

  The acrylic resin is used as a polymer binder, and the glass transition point of the acrylic resin is preferably 50 to 90 ° C, more preferably 60 to 80 ° C. If it is less than the lower limit, blocking between the films may occur, which is not preferable. If the upper limit is exceeded, the coating layer becomes brittle and the adhesiveness may not be maintained.

  As a specific acrylic resin, an acrylic resin obtained by polymerizing an acrylic monomer as exemplified below can be used. Specific acrylic monomers include alkyl acrylates and alkyl methacrylates (the alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, and 2-ethylhexyl groups. , Cyclohexyl groups, etc.); hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, and 2-hydroxypropyl methacrylate; epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether Acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrene sulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt) ) Or other carboxy group or a salt thereof; acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N, N-dialkylacrylamide, N, N-dialkylmethacrylate (the alkyl group is a methyl group) , Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxyacrylamide, N-alkoxymethacrylamide, N, N- Dialkoxyacrylamide, N, N-dialkoxymethacrylamide (alkoxy groups include methoxy, ethoxy, butoxy, isobutoxy, etc.), acryloylmorpholine, N-methylolacrylamide, N-methylolmethacrylamide Monomers containing amide groups such as N-phenylacrylamide and N-phenylmethacrylamide; monomers of acid anhydrides such as maleic anhydride and itaconic anhydride; vinyl isocyanate, allyl isocyanate, styrene, α-methyl styrene, vinyl methyl ether, Monomers such as vinyl ethyl ether, vinyl trialkoxysilane, alkylmaleic acid monoester, alkyl fumaric acid monoester, alkylitaconic acid monoester, acrylonitrile, methacrylonitrile, vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, butadiene Is mentioned.

  Among these, 2 to 20 moles of a hydroxyl group-containing monomer such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide and the like. %, Preferably 4 to 15 mol%.

The coating liquid may further contain a wetting agent, an antistatic agent, a colorant, a surfactant, an ultraviolet absorber, and the like. When the wetting agent is contained, the content is, for example, 1 to 20% by weight per 100% by weight of the solid content.
Moreover, it is preferable that the easily bonding coating film layer in this invention contains 5-20 weight% of crosslinking agents represented by following formula (I) with respect to the mass of a coating film layer.

  By containing the crosslinking agent, moisture resistance can be further improved. If the content is less than 5% by weight, the effect of improving moisture resistance is not exhibited, which is not preferable. If the content exceeds 20% by weight, it is difficult to form a coating film, and the adhesiveness to the polyfluorinated film may be deteriorated.

  A compound having another epoxy group may be used in combination with the crosslinking agent. Examples of these compounds include sorbitol tol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, Polyepoxy compounds such as methylolpropane polyglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether , Polypropylene glycol diglycidyl ether, polytetramethylene Diepoxy compounds such as recall diglycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, and monoepoxy compounds such as phenyl glycidyl ether.

[Manufacturing method of easily adhesive polyester film]
The easy-adhesion polyester film of the present invention has an easy-adhesion coating layer using the above-described components coated on at least one surface of the polyester film. This easy-adhesion coating layer is coated by applying, for example, an aqueous liquid containing a component that forms an easy-adhesion coating layer to a stretchable polyester film, followed by drying, stretching, and heat treatment as necessary. Is preferred. The solid content concentration of the aqueous liquid is usually 30% by weight or less, and more preferably 10% by weight or less.

  The stretchable polyester film is an unstretched polyester film, a uniaxially stretched polyester film, or a biaxially stretched polyester film in which a part of stretching has been completed. Of these, a longitudinally stretched polyester film uniaxially stretched in the film extrusion direction (longitudinal direction) is particularly preferred. By applying the coating liquid to the polyester film before the completion of the crystal orientation of the film and drying, stretching, and heat-treating it, adhesion to the fluorine-containing resin film described later can be expressed.

When applying an aqueous coating liquid to a film, as a pretreatment for improving the coating property, the film surface is subjected to physical treatment such as corona surface treatment, flame treatment, plasma treatment, etc., or chemically combined with the composition. It is preferable to use an inert surfactant in combination.
Such a surfactant promotes the wettability of the aqueous coating liquid to the polyester film. For example, polyoxyethylene alkylphenyl ether, polyoxyethylene-fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, Examples include anionic and nonionic surfactants such as alkyl sulfates, alkyl sulfonates, and alkyl sulfosuccinates. The surfactant is preferably contained in an amount of 1 to 10% by weight in the composition forming the coating film.

As the coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a roll brush method, a spray coating method, an air knife coating method, an impregnation method, and a curtain coating method can be used alone or in combination. The coating amount is preferably 0.5 to 20 g, more preferably 1 to 10 g, per 1 m ² of the running film. The aqueous liquid is preferably used as an aqueous dispersion or emulsion. In addition, a coating film may be formed only in the single side | surface of a film as needed, and may be formed in both surfaces.

A stretchable polyester film coated with an aqueous liquid is led to a drying and stretching process, which can be performed under conditions accumulated in the art. As preferable conditions, for example, the drying conditions are 90 to 130 ° C. × 2 to 10 seconds, the stretching temperature is 90 to 150 ° C., the stretching ratio is 3 to 5 times in the machine direction, and 3 to 5 times in the transverse direction. It is 1 to 3 times in the vertical direction, and 180 to 250 ° C. × 2 to 60 seconds when heat-fixed.
Although it depends on the application to be used, it is preferable that the easily-adhesive polyester film after the treatment has a thickness of 50 to 250 μm and the coating film has a thickness of 0.01 to 1 μm.

[Fluorine-containing resin film]
Examples of the fluorine-containing resin in the present invention include polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, polyethylene tetrafluoroethylene, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and tetrafluoroethylene. -A resin comprising a hexafluoropropylene copolymer or at least one of them and a polyolefin resin, a polyamide resin, a polyarylate resin, or the like.

  Among these, polyvinylidene fluoride is preferable from the viewpoint of weather resistance. Further, from the viewpoint of adhesiveness with the easy-adhesion polyester film of the present invention, a resin containing an acrylic resin in an amount of 25 to 75% by weight is preferable, and in particular, 25 to 75% by weight of polyvinylidene fluoride and an acrylic resin of 25 It is preferable to contain -75weight%.

As an acrylic resin, resin which consists of an acrylic monomer similar to the acrylic resin demonstrated by the above-mentioned easily bonding layer is mentioned.
Such a fluorine-containing resin film can be produced by a coating method in which a coating solution dissolved in a solvent is dried on a carrier sheet or by melt extrusion molding.

[Laminate]
The laminate of the present invention is obtained by laminating the above-mentioned fluorine-containing resin film directly on the above-mentioned easy-adhesion coating film layer of the above-mentioned easy-adhesion polyester film. As a laminating method, a fluorine-containing resin film may be stacked on the surface of the easy-adhesion coating film layer of the easy-adhesion polyester film of the present invention, and thermocompression-bonded with a hot press machine or the like. And according to this invention, the outstanding adhesiveness can be expressed, even if it does not use a urethane adhesive layer etc.

The following examples further illustrate the present invention. Each characteristic value was measured by the following method.
(1) Glass transition point (Tg)
The temperature was measured at a temperature increase rate of 20 ° C./min with a Thermal Analyst 2000 type differential calorimeter manufactured by DuPont.

(2) Thickness of each layer A film sample was cut into a triangle, fixed in an embedded capsule, and then embedded in an epoxy resin. The embedded sample was made into a thin film section having a thickness of 50 nm with a microtome (ULTRACUT-S) and then observed and photographed at an acceleration voltage of 100 kV using a transmission electron microscope. The thickness was measured.

(3) Adhesiveness of laminated body The obtained laminated body is subjected to a cross cut (100 squares of 1 mm2) from the surface of the fluorine-containing resin film, and a handy metal roll is used on it. A cellophane tape having a width of 24 mm (CT405AP manufactured by Nichiban Co., Ltd.) was completely attached and peeled off rapidly at a peeling angle of 180 °, and then the peeled surface was observed and evaluated according to the following criteria.
A: Peeling area <10% (very good)
○: 10% ≦ peeling area <30% (good)
×: 30% ≦ peeling area (defect)

(4) Adhesion evaluation after hot water treatment The obtained laminate was immersed in hot water at 90 ° C. for 30 minutes, and then cross-cut from the surface of the fluorine-containing resin film (100 squares of 1 mm 2) Using a hand-held metal roll, a 24 mm wide cellophane tape (Nichiban CT405AP) was completely applied and peeled off rapidly at a 180 ° peel angle, and then the peeled surface was observed. Evaluation was made according to the following criteria.
A: Peeling area <10% (very good)
○: 10% ≦ peeling area <30% (good)
×: 30% ≦ peeling area (defect)

[Example 1]
Polyethylene terephthalate having an intrinsic viscosity of 0.62 dl / g was heated to 285 ° C. and melt-extruded from a die onto a rotary cooling drum maintained at 20 ° C. to obtain an unstretched film. Next, the film was stretched 3.2 times at 100 ° C. in the longitudinal direction, and then a coating composition for an easy-adhesion coating film layer shown in Table 1 below was applied to both sides of the film on a roll coater in a state of an aqueous coating solution having a concentration of 8%. It was applied evenly.
Subsequently, this coated film was subsequently dried at 95 ° C., stretched 3.4 times at 110 ° C. in the transverse direction, and thermally fixed by shrinking 3% in the width direction at 225 ° C., and a 125 μm thick easily adhesive polyester film Got. In addition, the thickness of the coating film was 0.08 micrometer, respectively.
One sheet of this easy-adhesive polyester film cut to 100 mm width × 100 m length is prepared, and one sheet of a PVDF film cut to 50 mm width × 50 mm length is prepared as a fluorine-containing resin film.
As the PVDF film, Solvay Advance Co., Ltd., trade name SOLEF6010 is prepared as PVDF, and this is applied to a small twin-screw extruder manufactured by Toyo Seiki Seisakusho (labora plast mill: twin screw full flight 2D25S type) at 300 ° C. The film was supplied at a flow rate of 2 Kg / Hr and melt-extruded under the condition of 240 ° C. to form a film having a thickness of 25 μm.
With a hot press machine, stack the easy-adhesive polyester film / PVDF film in order, so that the PVDF film is located almost in the center of the easy-adhesive polyester film, and the surface to be evaluated for adhesiveness is on the PVDF side. Thermocompression bonding was performed. The pressure-bonding conditions were as follows: pressure bonding was performed at 200 ° C. and 1 MPa for 1 minute, and then the press pressure was raised to 5 MPa and pressure bonding was performed for 1 minute to produce a laminate of a fluorine-containing resin film / an easily adhesive polyester film. These evaluation results are shown in Table 1.

[Example 2]
A laminate was prepared in the same manner as in Example 1 except that a resin composition part in which PVDF and PMMA were mixed at a weight ratio of 75:25 was used instead of PVDF. The evaluation results are shown in Table 1.

[Example 3]
A laminate was prepared in the same manner as in Example 1 except that a resin composition in which PVDF and PMMA were mixed at a weight ratio of 50:50 was used instead of PVDF. The evaluation results are shown in Table 1.

[Example 4]
A laminate was produced in the same manner as in Example 1 except that a resin composition in which PVDF and PMMA were mixed at a weight ratio of 25 to 75 was used instead of PVDF. The evaluation results are shown in Table 1.

[Examples 5 to 7]
As shown in Table 1, the same operation as in Example 1 was repeated except that the contents of the binder and the surfactant were changed. The evaluation results are shown in Table 1.

[Comparative Example 1]
The same operation as in Example 1 was repeated except that the composition of the easy-adhesion coating layer was changed as shown in Table 1. Table 1 shows the results of the evaluation of the obtained easily adhesive polyester film and the laminate.

[Comparative Example 2]
The same operation as in Example 1 was repeated except that the easy adhesion coating layer was not formed. Table 1 shows the results of the evaluation of the obtained easily adhesive polyester film and the laminate.

[Comparative Example 3]
A polyester film was obtained in the same manner as in Example 1 except that the aqueous liquid was not applied. An aqueous coating solution having a concentration of 8% of the coating composition for the easy adhesion coating layer shown in Table 1 below was uniformly applied to both surfaces of the biaxially stretched polyester film with a roll coater. Subsequently, the coated film was subsequently dried at 225 ° C. to prepare an easily adhesive polyester film having an easily adhesive layer by an off-line coating method. The film was subjected to thermocompression bonding in the same manner as in Example 1 to prepare a laminate of a fluorine-containing resin film / an easily adhesive polyester film. Table 1 shows the results of evaluation of the easily adhesive polyester film and the laminate.

[Comparative Examples 4 and 5]
As shown in Table 1, the same operation as in Example 1 was repeated except that the contents of the binder and the surfactant were changed. The evaluation results are shown in Table 1.

  The acrylic binder in Table 1 is manufactured by Nippon Pure Chemical Co., Ltd., trade name: N-31-4, the polyester binder is manufactured by Takemoto Yushi Co., Ltd., trade name: TPE-62C, and the crosslinking agent A is manufactured by Mitsubishi Gas Chemical Co., Ltd. : TETRAD-X, crosslinker B manufactured by Nippon Shokubai Co., Ltd., trade name: Epocross WS-700, surfactant means Kao Chemicals Co., Ltd., trade name: Emulgen A-60.

  The easily-adhesive polyester film of the present invention is excellent in adhesiveness with a polyfluorinated film, and can be suitably used as a laminate for a solar cell back surface protective film or the like.

Claims (6)

An easy-adhesion polyester film provided with an easy-adhesion coating film layer on at least one side,
The easy-adhesion coating layer contains acrylic resin in the range of 70 to 95 wt%, and is applied before the stretching of the oriented polyester film is completed; and
An easy-adhesive polyester film, wherein a fluorine-containing resin film is directly laminated on the easy-adhesive coating film layer.   The easily adhesive polyester film according to claim 1, wherein the easily adhesive coating film layer contains an epoxy-based crosslinking agent in a range of 1 to 5 wt% based on the mass thereof.   A laminate comprising the easily adhesive polyester film according to claim 1 and a fluorine-containing resin film directly laminated on the surface of the easily adhesive coating film layer.   4. The laminate according to claim 3, wherein the fluorine-containing resin film contains a fluorine resin as a main constituent and contains an acrylic resin in a range of 25 to 75 wt% based on the mass of the fluorine-containing resin film.   The laminated body in any one of Claim 3 or 4 used for a solar cell back surface protective film.   After applying a coating liquid containing an acrylic resin in a range of 70 to 95 wt% to at least one surface of the polyester film before the completion of the stretching treatment, a step of performing a stretching treatment to obtain an oriented polyester film was obtained. The manufacturing method of the laminated body which forms a fluorine-containing resin film directly on the easily-adhesive coating film layer of an easily-adhesive polyester film.