JP2544792B2 - Laminated film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyester film having excellent surface properties, particularly adhesiveness when laminated with other materials. More specifically, a laminated polyester useful as a base material for magnetic recording media, graphic arts, displays, building materials, packaging materials, electrical insulation and general industrial applications, which are higher-order processed products by methods such as printing, coating, vapor deposition and laminating. Regarding film.

[Prior Art and Problems to be Solved by the Invention] Biaxially stretched polyester films are widely used because they have excellent properties, but depending on the application,
It has the drawback of poor adhesion.

As a method of improving the adhesiveness of the biaxially stretched polyester film, a method of forming a copolymerized polyester into a film, a method of blending a polymer such as polyether, a method of treating the film with a solvent, a corona discharge treatment, a plasma treatment, etc. However, in these methods, the effect of improving the adhesiveness is limited, and the method of laminating an adhesive polymer by a coating treatment is effective.

As a method for producing a biaxially stretched polyester film having a coating layer, there is one called a coating stretching method (in-line coating method) in which a coating solution is coated and then the film is stretched and heat-treated. Compared with the method of forming a coating layer by coating the coating liquid on the polyester film after biaxial stretching, this method performs film formation and coating at the same time, so a wide product can be obtained at a relatively low cost. In addition, the adhesiveness between the coating layer and the polyester film of the substrate is good, and not only the coating layer can be made thin, but also the surface characteristics of the coating layer are characteristic.

As a coating agent used in the coating and stretching method, many proposals have been made such as polyester, polyurethane, acrylic resin and vinyl resin.

For example, a polyester film having a specific polyurethane as a coating layer by a coating stretching method is disclosed in JP-A-55-15
825, JP-A-56-135547, JP-A-61-26132
No. 4, JP 61-261325, JP 61-261326
It is proposed in Japanese Patent Publication No.

Further, the one in which the defect of the characteristics of polyurethane is improved by blending polyester or acrylic resin is disclosed in JP-A-58-78.
761, JP-A-62-204939, JP-A-62-20494
It is proposed in the publication No. 0 and the like. However, as the uses of the polyester film have expanded, stronger adhesive force and adhesiveness to new materials have been required.

[Means for solving the problem]

In view of the above problems, the inventors of the present invention have made extensive studies and found that a polyester film having a specific polyurethane as a coating layer has excellent surface properties such as adhesiveness, and completed the present invention.

That is, the gist of the present invention resides in a polyester film having a coating layer obtained by a coating stretching method, wherein the coating film contains polyurethane having polycarbonate as a constituent component.

 Hereinafter, the present invention will be described in more detail.

The polyester of the polyester film constituting the substrate in the present invention is polyethylene terephthalate in which 80 mol% or more of its constituents is ethylene terephthalate or polyethylene naphthalate in which 80 mol% or more is ethylene naphthalate. Examples of constituent components of polyesters other than ethylene terephthalate and ethylene naphthalate include diols such as diethylene glycol, propylene glycol, neopentyl glycol, 1,4-butylene glycol, 1,4-cyclohexanedimethanol, polyethylene glycol, and polytetramethylene glycol. Component, dicarboxylic acid component such as isophthalic acid, 5-sodiosulfoisophthalic acid, adipic acid, sebacic acid and its ester-forming derivative, oxycarboxylic acid such as oxybenzoic acid and its ester-forming derivative, etc. can be used. However, it is not limited thereto.

The polyester film constituting the substrate in the present invention may contain so-called added particles or precipitated particles, polyester having a characteristic different from that of the polyester of the substrate, or a polymer other than polyester in order to form protrusions on the surface of the film. The surface roughness of the polyester film of the substrate is selected by the person skilled in the art by selecting the type, size and blending amount of the protrusion-forming agent according to the required properties such as slipperiness and transparency of the product in which the polyester film of the present invention is used. It can be realized by a known method.

Examples of the composition other than the projection forming agent of the polyester film constituting the substrate include an antistatic agent, a stabilizer, a lubricant, a colorant, a light blocking agent, etc. depending on the required characteristics of the product in which the polyester film of the present invention is used. May be contained.

For the characteristics such as orientation, crystallinity, mechanical characteristics and dimensional stability of the polyester film constituting the substrate, the film production conditions well known to those skilled in the art can be selected according to the required characteristics of the product in which the polyester film of the present invention is used. It can be realized by doing.

The polyurethane having a polycarbonate as a constituent in the present invention is one in which polycarbonates are used as one of the polyols as a main constituent of the polyurethane-forming component.

Examples of the polyisocyanate component of the polyurethane having a polycarbonate in the present invention include tolylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate. , Isophorone diisocyanate, etc.

Examples of polyol components other than polycarbonates include polyethers such as polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyethylene adipate, polyethylene-butylene adipate, polyesters such as polycaprolactone, and acrylic. Examples include polyols and castor oil.

Examples of chain extenders or crosslinkers include ethylene glycol, propylene glycol, butanediol,
Diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine, 4,
4'-diaminodiphenylmethane, 4,4'-diaminodicyclohexylmethane, water and the like.

Specific examples of polycarbonates or polyurethanes having polycarbonate as a constituent component include Japanese Patent Publication No. 46-
4191, JP-B-49-2358, JP-A-55-56124
The compounds described in JP-A Nos. 58-60430 and 63-165418 can be used.

Polycarbonates are obtained, for example, by reacting a carbonic acid ester with a diol. Examples of carbonic acid esters are ethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, dicyclohexyl carbonate, and examples of diols are 1,6-hexanediol, 1,4-cyclohexanedimethanol, and 3-methyl-1,5. -Pentanediol, 1,5
-Pentanediol, polyoxyethylene glycol,
Examples thereof include, but are not limited to, polyoxypropylene glycol, polyoxybutylene glycol, polycaprolactone diol, trimethylhexanediol, and 1,4-butanediol.

Further, as polycarbonates, JP-A-58-60430
It may be a polyester polycarbonate obtained by reacting a polycarbonate diol with a dicarboxylic acid or a polyester as described in JP-B-49-2358.

Polyurethane having polycarbonate as a constituent in the present invention may be one using a solvent as a medium,
Preferably, the medium is water. When water is used as the medium, it may be forcibly dispersed by a surfactant or the like, but is preferably described in JP-B-63-12890 or a hydrophilic nonionic component such as polyethers. It is a self-dispersion type in which a cationic component as described above is bonded to polyurethane, more preferably Angew, M
akromol, Chem., 98 133-165 (1981). It is of a self-dispersion type in which an anionic component as described in, for example, is bonded to polyurethane.

The polyurethane having an anionic component is a method of using a compound having an anionic group as a polyurethane-forming component such as a polyol, a polyisocyanate compound and a chain extender, and a compound having an unreacted isocyanate group and an anionic group of the generated polyurethane. How to react,
It can be produced by a method of reacting a group having active hydrogen of polyurethane with a specific compound.

In the method of using a compound having an anionic group as the polyurethane-forming component, for example, a compound obtained by a method of sulfonating an aromatic isocyanate compound, a diaminocarboxylic acid salt, a sulfuric acid ester salt of amino alcohols, or the like can be used.

The method for reacting the unreacted isocyanate group of the polyurethane with the compound having an anionic group is, for example, bisulfite, aminosulfonic acid and salts thereof, aminocarboxylic acid and salts thereof, sulfuric acid ester of aminoalcohols and salts thereof, hydroxy. Acetic acid and its salts can be used.

The method of reacting the group having an active hydrogen of polyurethane with a specific compound is, for example, dicarboxylic acid anhydride, tetracarboxylic acid anhydride, sultone, lactone, epoxycarboxylic acid, epoxysulfonic acid, 2,4-dioxo-oxazolidine, isato. Indicates a salt type group such as acid anhydride, hoston, carbyl sulfate, or a group capable of forming a salt after ring opening 3
A cyclic compound having a member ring to a 7-membered ring can be used.

In the case of polyester polyurethane, an anionic group can be introduced into the polyurethane by using a polyester having an anionic group. The polyester having an anionic group is a polyester having a compound having a sulfonate group or a carboxylate group bonded to the polyester by copolymerization or grafting.

In particular, the polyurethane used in the present invention has a molecular weight of 30.
Resins comprising 0 to 20,000 polycarbonates and polyols, polyisocyanates, chain extenders having reactive hydrogen atoms and groups which react with isocyanate groups, and compounds having at least one anionic group are preferred.

Anionic groups in the polyurethane, -SO ₃ H, -OSO
_It is used as a lithium salt, sodium salt, potassium salt, magnesium salt, or ammonium salt of ₃ H, —OOOH or the like.

The amount of anionic groups in polyurethane is from 0.05% by weight to
8% by weight is preferred. With a small amount of anionic group, the water solubility or water dispersibility of the polyurethane is poor, and with a large amount of anionic group, the water resistance of the undercoat layer after coating may be poor,
This is because the films are easily absorbed due to moisture absorption.

The content of the polycarbonate component in the polyurethane is usually 10 to 90% by weight, preferably 20 to 70% by weight. If the content is less than 10% by weight, the effect of improving the adhesiveness of polyurethane is poor, and if it exceeds 90% by weight, the coating property is deteriorated, which is not preferable.

The coating liquid in the present invention contains a urea-based, melamine-based, or guanamine-based methylol- or alkylol-based crosslinking agent for improving the adhesion (blocking property), water resistance, solvent resistance, and mechanical strength of the coating layer. , Acrylamide-based, polyamide-based compounds, epoxy compounds, aziridine compounds, blocked polyisocyanates, silane coupling agents, titanium coupling agents, zircoaluminate coupling agents, heat, peroxides, photoreactive vinyl compounds Or a photosensitive resin may be contained. In addition, silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, titanium oxide, barium salt, carbon black, molybdenum sulfide, antimony oxide sol, etc., are used as the inorganic fine particles for the purpose of improving stickiness and slipperiness. It may contain, further as necessary antifoaming agent, coatability improver, thickener, antistatic agent, organic lubricant, organic polymer particles, antioxidant,
It may contain an ultraviolet absorber, a foaming agent, a dye, a pigment and the like. Further, the coating liquid of the present invention contains another kind of polyurethane or polyester, acrylic resin, vinyl resin or the like as a polymer other than polyurethane having the polycarbonate of the present invention as a constituent component for improving the characteristics of the coating liquid or the coating layer. You may have.

As a method for applying the above-mentioned coating liquid to a polyester film, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater or any other coating device shown in "Coating Method" by Yuji Harasaki, Maki Shoten, issued in 1979. A method of applying a coating solution to a polyester unstretched film using, and sequentially or simultaneously biaxially stretching, a method of applying a uniaxially stretched polyester film, and further stretching in a direction perpendicular to the uniaxially stretching direction. Further, there are a method of re-stretching a biaxially stretched film having these coating layers, a method of coating a biaxially stretched polyester film, and further stretching in a transverse and / or longitudinal direction.

The above-mentioned stretching step is preferably carried out at 60 to 130 ° C, and the stretching ratio is at least 4 times or more, preferably 6 to 20 times in terms of area ratio. Stretched film is 150-250
Heat treated at ℃.

Furthermore, in the maximum temperature zone of heat treatment and / or in the cleaning zone at the heat treatment outlet, 0.2 to 20% in the vertical and horizontal directions.
It is preferable to relax.

In particular, the coating solution is applied to a uniaxially stretched polyester film stretched 2 to 6 times by a roll stretching method at 60 to 130 ° C. and dried appropriately, or the uniaxially stretched polyester film is not immediately dried immediately before It is preferable that the film is stretched in a direction perpendicular to the stretching direction at 2 to 6 times at 80 to 130 ° C. and heat treated at 150 to 250 ° C. for 1 to 600 seconds.

According to this method, the coating layer can be dried at the same time as stretching, and the thickness of the coating layer can be thinned according to the stretching ratio, so that a film suitable as a polyester film substrate can be produced at a relatively low cost. it can.

The coating liquid in the present invention may be applied to only one surface of the polyester film or may be applied to both surfaces. When coated on only one side, a coating layer other than the coating liquid of the present invention may be formed on the opposite side, if necessary, to impart other properties to the polyester film of the present invention. In addition, in order to improve the coating property and the adhesive property of the coating agent on the film, the film may be subjected to a chemical treatment or a discharge treatment before the coating. Further, in order to improve the adhesion to the coating layer of the biaxially stretched polyester film of the present invention, the coating property,
After forming the coating layer, the coating layer may be subjected to discharge treatment.

The polyester film coated with the coating liquid of the present invention obtained as described above preferably has a polyester film thickness of 3 to 500 μm, and the coating layer preferably has a thickness of 0.01 to 5 μm. More preferably
It is in the range of 0.02 to 1 μm. If the thickness of the coating layer is less than 0.01 μm, it is difficult to obtain a uniform coating layer, so that coating unevenness is likely to occur in the product.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

 The evaluation methods in the examples are shown below.

Adhesiveness evaluation Nichiban Cellotape (18 mm
Width) is attached to a length of 7 cm so that air bubbles do not enter, and 3 kg on this
A constant load was applied by using the above manual load roll. The film was fixed, one end of the cellophane tape was connected to a weight of 500 g, and after the weight naturally dropped at a distance of 45 cm, the peel test in the 180 ° direction was started.

Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.62 was added to 280 to 3
It was melt extruded at a temperature of 00 ° C. and cast on a cooling drum while also using the electrostatic adhesion method to obtain an amorphous polyester film having a thickness of 820 μm. After stretching this film 3.3 times in the longitudinal direction at 95 ° C., it is composed of polycarbonate of Toagosei Co., Ltd., and is an aqueous dispersion type polyurethane having anionic group, Aron Neotan UE-1300 (trade name) 70 parts (Weight of solid content, the same applies below), Finetex, a water-dispersible polyester from Dainippon Ink and Chemicals, Inc.
A coating solution containing 20 parts of ES-670 (trade name) and 10 parts of alkylol melamine in water as a medium is applied to both sides of the film, further stretched 3.3 times in the transverse direction at 110 ° C, and heat treated at 210 ° C. A biaxially stretched polyester film having a coating layer thickness of 0.12 μm and a substrate polyester film thickness of 75 μm was obtained.

An ultraviolet-curable ink layer and an oxidative-curable ink layer were formed on one surface of the above film as described in (A) or (B) below.

(A) UV-curable ink layer PCD white (trade name), which is a UV-curable offset ink from Moroboshi Ink Co., is so-called solid-printed with an RT tester (trade name), which is an offset printing tester manufactured by Ming Seisakusho, UVH-2000, a UV irradiation device manufactured by USHIO INC.
The mold (trade name) was subjected to ultraviolet curing at a curing condition of 120 W / cm and a film speed of 12 m / min to obtain a film having a printing ink layer thickness of 1 μm.

(B) Oxidation-curable ink layer RAM, which is an oxidation-curable ink from Seiko Advance Inc.
So-called solid printing was performed on black (trade name) using a silk screen, and the film was left for one day and night to obtain a film having a printing ink layer thickness of 10 μm.

All of the obtained films were films having excellent adhesiveness in which peeling of the ink layer did not occur in the adhesiveness evaluation.

Moreover, instead of these ink layers, SD-40, a coating agent for diazo photosensitive type screen printing manufactured by Kurita Chemical Laboratory
(Product name) was screen-printed to obtain a film having an ink layer with a thickness of 6 μm. The obtained film had excellent adhesiveness in the evaluation of adhesiveness.

Comparative Example A film having a thickness of 75 μm was obtained in the same manner as in Example 1 except that the coating liquid was not applied. A curable ink layer or a screen printing ink layer was provided on the obtained film in the same manner as in Example 1. In the obtained film, the ink layer was completely peeled from the substrate in the evaluation of adhesiveness.

Example 2 Polyethylene terephthalate having an intrinsic viscosity of 0.65 was added to 280 to 3
It was melt-extruded at a temperature of 00 ° C. and cast on a cooling drum while also using the electrostatic adhesion method to obtain an amorphous polyester film having a thickness of 192 μm. This film is stretched 4.0 times in the longitudinal direction at 95 ° C, and contains polycarbonate from Toagosei Kagaku Kogyo Co., Ltd. as a constituent component, Alon Neotan UE-1402 (trade name), which is a water-dispersible polyurethane having an anion group. , Consisting of 10 parts of Polyester R961 (trade name), a water-dispersible polyester having anionic groups, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., and 10 parts of Denacol EX-521 (trade name), an aqueous epoxy compound manufactured by Nagase Kasei Co., Ltd. A coating solution using water as a medium is applied to one side of the film, further stretched 4.0 times in the transverse direction at 110 ° C, and heat-treated at 220 ° C to give a coating layer thickness of 0.05 μm, and a polyester film thickness of 12 μm as a substrate.
Was obtained.

On the coated layer surface of the obtained polyester film, a printing layer with a thickness of 5 μm was formed with a gravure printing machine using Cellocolor CCST (trade name), which is a printing ink for cellophane using Nitrocellulose manufactured by Toyo Ink Mfg. Co., Ltd. as the main binder. Formed. The obtained film was good in the evaluation of adhesiveness.

Example 3 Example 2 was repeated except that Neoletz XR-9605 (trade name), which is a water-dispersible polyurethane having an anionic group and having a polycarbonate of Polyvinyl Chemical Co. as a constituent component, was used in place of the polyurethane of Toagosei Kagaku Kogyo Co., Ltd. When a polyurethane film having a coating layer was prepared in the same manner as in Example 2 and its adhesiveness was evaluated, excellent properties were exhibited.

〔The invention's effect〕

The film of the present invention is an ink layer laminated on the coating layer,
It has excellent adhesion to magnetic layers, metal layers, resin layers, etc., and is useful as a base material for various applications such as magnetic recording media, graphic arts, displays, building materials, packaging materials, and electrical insulation, and its industrial value is high. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masato Fujita 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa DIAFOIL Co., Ltd. Central Research Laboratory (56) Reference JP-A-62-59636 (JP, A)

Claims (1)

(57) [Claims] 1. A polyester film having a coating layer obtained by a coating stretching method, wherein the coating layer contains polyurethane containing polycarbonate as a constituent component.