JPH0124630B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a polyester film laminate and its manufacturing method, and more specifically to highly processed products such as audio magnetic tape, video magnetic tape, computer magnetic tape, floppy disk, and X-ray photography. The present invention relates to a polyester film laminate useful as a base material for films and the like and having excellent adhesiveness and solvent resistance, and a method for producing the same. Prior Art It is known to melt extrude thermoplastic polyesters, such as polyethylene terephthalate or its copolymers, polyethylene naphthalate or its copolymers, or blends thereof with small proportions of other resins, to form films. It is also known that the resulting biaxially stretched and heat-set polyester film has better heat resistance, gas barrier properties, electrical properties, and chemical resistance than films made of other resins. However, since the surface is highly crystal oriented, the surface has high cohesion and poor receptivity to paints, adhesives, inks, and the like. Therefore, when a synthetic resin layer is provided on the surface of such a polyester film, the film surface is subjected to corona discharge treatment in order to strengthen the adhesion between the two.
A method is used in which the surface is activated by ultraviolet irradiation treatment, plasma treatment, or flame treatment and then coated with a synthetic resin coating. however,
Although these methods of activating the film surface can be expected to improve adhesion to the coating layer by increasing the secondary bonding force due to wetting, the activity decreases over time. Therefore, these means of activating the film surface are not always satisfactory. As another method for increasing the receptivity of the polyester film surface, an etching method has been proposed in which the surface is swollen or partially dissolved with various chemicals. This involves etching the film surface by bringing it into contact with chemicals such as acid, alkali, amine aqueous solution, trichloroacetic acid, or phenols, decomposing, dissolving, and relaxing the crystal orientation near the surface, and at the same time reducing cohesion. This is intended to increase the adhesiveness with the binder resin by reducing the
The effect is most reliable, and the adhesion between the film and the layer provided thereon, such as a synthetic resin coating layer, becomes strong. However, some of the chemicals used in this method are harmful, and there is a risk that they may be dangerous to handle, or that volatile substances from the chemicals may be released into the atmosphere. There are various disadvantages in practical terms, such as the need for extreme caution. As a method similar to this method, a primer layer (undercoat layer) is provided on the surface of the film in advance, a thin surface layer that is different from the base film is formed, and then a desired layer, such as a synthetic resin layer, is coated. be. When forming the undercoat layer, a coating process is usually performed in a process different from the polyester film forming process. However, advanced processed film products such as audio magnetic tape, video magnetic tape, computer magnetic tape,
In applications such as floppy discs, X-ray photographic films, photographic films for printing, and diazo microfilms, which must maintain precision and delicate quality, even if an easily adhesive surface is successfully formed, the resulting film If there are surface defects due to dust, the base film cannot be used for these purposes, but this defect is likely to occur in this separate process. Therefore, it is desirable to perform the undercoating process in an atmosphere as free from dust as possible. There is a polyester film forming process that satisfies these conditions, and if undercoating is performed in this process, a product that can be fully used for the above-mentioned advanced film processed products can be obtained. On the other hand, in the prior art, methods for modifying the surface of a polyester film into an easily adhesive surface by treating the surface with a primer are often achieved by applying a composition dissolved in an organic solvent to the surface layer of the film. I came. If such a method is carried out during film production, it may cause contamination of the surrounding environment by deviated organic solvents,
resulting in unfavorable safety and hygiene conditions,
The use of organic solvents should be kept to a minimum as much as possible since they adversely affect the film forming process. Therefore, when performing in-line subbing treatment in the film forming process, it is preferable to use a composition using water as a solvent from the viewpoints of process, economy, and safety. Therefore, many primer compositions using water as a solvent have been proposed, and in particular, many proposals have been made for aqueous solutions or dispersions of polyurethane or polyester. For example, Japanese Patent Publication No. 46-10193 discloses the use of polyurethane having solvent resistance to acetone and water dispersibility. However, these primer compositions swell or dissolve in solvents used in magnetic paints, such as methyl ethyl ketone, cyclohexanone, tetrahydrofuran, etc., and are insufficient in terms of solvent resistance. When a highly polar paint such as a magnetic paint is applied on such a primer layer, mixing of the primer layer and the magnetic layer occurs, which not only reduces the adhesion effect of the primer layer but also causes streaks on the surface of the applied layer. A good coated surface cannot be obtained.
Particularly in recent years, recording densities have been increasing in coated magnetic recording media, and magnetic layers are becoming thinner. Among these, there is a trend toward thinner floppy disks.
In particular, the thickness of floppy disks has been rapidly reduced to about 1 μm. When the magnetic layer becomes thin in this manner, the above-mentioned flow lines generated on the surface of the magnetic layer make it difficult to obtain a good magnetic surface and cause deterioration of electromagnetic conversion characteristics, which is not preferable. Object of the invention The object of the invention is to apply various coatings applied to polyester films, such as cellophane inks, magnetic paints, gelatin compositions, offset inks, electrophotographic toners, chemical matte paints, diazo paints, and heat-sealable compositions. It has excellent adhesion to materials, inorganic film-forming substances, etc., does not cause run streaks when coating these materials, and has stable solvent resistance that is not affected by the drying conditions of the coating solution. An object of the present invention is to provide a polyester film laminate coated with a primer layer. Another object of the present invention is to provide a preferred method for producing such a polyester film laminate. Structure of the Invention According to the present invention, at least one side of the polyester film contains (1) an aqueous polyurethane having at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base; (2)
A polyester film laminate provided with a primer layer formed by reacting an epoxy compound having two or more epoxy groups in the presence of (3) a reaction accelerating compound, and at least one side of the polyester film before crystal orientation is completed. (1) an aqueous polyurethane containing at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base; (2) an epoxy compound having two or more epoxy groups; and (3) an aqueous polyurethane containing a reaction accelerating compound. This is achieved by a method for producing a polyester film laminate, which is characterized by applying a primer coating solution, followed by drying, stretching, and heat treatment to complete crystal orientation. In the present invention, polyester is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-
Examples include 2,6-naphthalene dicarboxylate, and also include copolymers thereof or blends of these with a small proportion of other resins. The polyester film of the present invention is obtained by melt-extruding such a linear saturated polyester resin, forming it into a film by a conventional method, and subjecting it to oriented crystallization and heat treatment crystallization. This polyester film is crystal oriented to such an extent that the heat of crystal fusion measured by a scanning calorimeter in a nitrogen stream (at a heating rate of 10°C/min) is usually 4 cal/g or more. preferable. In the present invention, the polyester film before crystal orientation is completed is an unstretched film obtained by thermally melting the polymer and forming it into a film as it is;
A uniaxially stretched film in which an unstretched film is oriented either vertically or horizontally; This includes biaxially stretched films (before stretching to complete oriented crystallization). The aqueous primer coating liquid used in the present invention comprises (1) an aqueous polyurethane containing at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base, (2) an epoxy compound having two or more epoxy groups, and ( 3) Contains a reaction accelerating compound. This aqueous polyurethane has an increased affinity for water by a carboxylic acid group, a sulfonic acid group, or a sulfuric acid half-ester base, and such water affinity-imparting groups are usually introduced during or after the synthesis of the polyurethane. For example, a carboxylic acid group can be introduced by using a carboxylic acid group-containing polyhydroxy compound as one of the raw material polyhydroxy compounds during polyurethane synthesis, or by introducing a hydroxyl group-containing carboxylic acid or an amino acid group into the isocyanate group of a polyurethane having unreacted isocyanate groups. This can be carried out by reacting a group-containing carboxylic acid, and then adding the reaction product to an aqueous alkaline solution under high speed stirring to neutralize it. In addition, the introduction of a sulfonic acid group or a sulfuric acid half-ester base is usually carried out by forming a prepolymer from a polyhydroxy compound, a polyisocyanate, and a chain extender, and adding an amino group or a hydroxyl group that can react with the terminal isocyanate group and a sulfonic acid group or This can be carried out by adding and reacting a compound having a sulfuric acid half ester base in its molecule, and finally obtaining an aqueous polyurethane having a sulfonic acid group or a sulfuric acid half ester base in its molecule. In this case, it is preferable to carry out the formation reaction in an organic solvent, then add water and then remove the solvent. Another method is to synthesize a polyurethane having a sulfonic acid group using a compound having a sulfonic acid group as one of the raw materials, and then add the polyurethane to an alkaline aqueous solution under high speed stirring to neutralize it. Examples include a method of adding the following sultone compound to the primary or secondary amino group of the main chain or side chain of polyurethane in the presence of an alkali to introduce an alkali sulfonic acid salt (e.g. -SO ₃ Na, etc.). It will be done. As the alkaline aqueous solution, it is preferable to use an aqueous solution of sodium hydroxide, potassium hydroxide, ammonia, alkylamine, etc.
Ammonia, in which the alkali does not remain in the coating film (undercoat film), and amine, which evaporates under drying conditions, are particularly preferred. The amount of bases such as carboxylic acid groups, sulfonic acid groups, and sulfuric acid half-ester bases is preferably 0.5 to 15% by weight. If the proportion of the base is too small, the water affinity of the polyurethane will be insufficient, making it difficult to prepare a coating solution, and if it is too large, the properties of the polyurethane itself will be impaired, which is not preferable. Such aqueous polyurethane forms a stable aqueous dispersion or aqueous solution using a dispersion aid if desired. Examples of polyhydroxy compounds used in the synthesis of polyurethane include polyethylene glycol,
Polypropylene glycol, polyethylene/propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, polycaprolactone, polyhexamethylene adipate, polyhexamethylene sebacate, polytetra Examples include methylene adipate, polytetramethylene sebacate, trimethylolpropane, trimethylolethane, pentaerythritol, and glycerin. Examples of the polyisocyanate compound include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, an adduct of tolylene diisocyanate and trimethylolpropane, an adduct of hexamethylene diisocyanate and trimethylolethane, and the like. . Examples of the carboxylic acid-containing polyol include dimethylolpropionic acid, dimethylolbutyric acid, dimethylolvaleric acid, and trimellitic acid bis(ethylene glycol) ester. Examples of the amino group-containing carboxylic acid include β-aminopropionic acid, γ-aminobutyric acid, and P-aminobenzoic acid. As the hydroxyl group-containing carboxylic acid, for example, 3-
Hydroxypropionic acid, γ-hydroxybutyric acid,
Examples include P-(2-hydroxyethyl)benzoic acid and malic acid. Examples of compounds having an amino group or a hydroxyl group and a sulfonic group include aminomethanesulfonic acid, 2-aminoethanesulfonic acid, and 2-amino-5-methylbenzene-2-
Examples include sulfonic acid, sodium β-hydroxyethanesulfonate, propane sultone adducts of aliphatic di-primary amine compounds, butane sultone adducts, and preferably propane sultone adducts of aliphatic di-primary amine compounds. can give. Furthermore, examples of compounds containing an amino group or a hydroxyl group and a sulfuric acid half-ester group include aminoethanol sulfuric acid,
Examples include ethylenediamine ethanol sulfate, aminobutanol sulfate, hydroxyethanol sulfate, γ-hydroxypropanol sulfate, α-hydroxybutanol sulfate, and the like. Polyurethane can be synthesized using these compounds by conventionally well-known methods. Examples of epoxy compounds having two or more epoxy groups that react with aqueous polyurethane include and water-soluble or water-dispersible epoxy compounds such as addition condensates of bisphenol A and epichlorohydrin. Examples of compounds that promote the reaction between aqueous polyurethane and epoxy compounds (reaction promoting compounds) include tertiary amino group-containing compounds and salts thereof, compounds having a nitrogen-containing ring structure and salts thereof, tetraammonium salt compounds, etc. Can be done. More specifically, examples of tertiary amino group-containing compounds include trimethylamine, triethylamine, tri-
Examples include n-butylamine, dimethylaminobenzene, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and examples of compounds having a nitrogen-containing ring structure and salts thereof include 2-methyl imidazole, 2-methyl-4-ethylimidazole, 2-ethylimidazole, 2
-isopropylimidazole, 2-phenyl-4
Examples include imidazole compounds such as -methylimidazole, 1,8-diazo-bicyclo(5,4,0)undecene-7, and their hydrochlorides and carbonates. Examples of the quaternary ammonium salt compound include triethylbenzylammonium chloride and tetramethylammonium chloride. 3 of these
More preferred are compounds containing a grade amino group and compounds having a nitrogen-containing structure. The aqueous primer coating liquid used in the present invention may be an aqueous solution or an aqueous dispersion,
There are no particular restrictions. The ratio of the aqueous polyurethane to the epoxy compound is preferably 1 to 40 parts by weight, more preferably 2 to 30 parts by weight, per 100 parts by weight. If the proportion of the epoxy compound is too high, the adhesion properties will be lowered, and if it is too low, the solvent resistance will be lowered, making it difficult to obtain a good coated surface when the coating is applied, which is the object of the present invention, which is not preferable. In addition, the ratio of the epoxy compound to the reaction accelerating compound is 100 parts by weight of the former, 1 to 60 parts by weight of the latter,
Preferably it is 5 to 50 parts by weight. If the effect of promoting the reaction is not sufficient, and if the amount is too large, it becomes difficult to control the reaction and the stability of the coating liquid decreases. The aqueous primer coating solution is made by dissolving or dispersing the above three components in an aqueous medium, but it is also possible to add a necessary amount of a surfactant such as an anionic surfactant or a nonionic surfactant. .
Such a surfactant is preferably one that can lower the surface tension of the aqueous coating solution to 40 dyne/cm or less and promotes wetting to the polyester film, such as polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan, etc. Examples include fatty acid esters, glycerin fatty acid esters, fatty acid metal soaps, alkyl sulfates, alkyl sulfonates, alkyl sulfonates, and alkyl sulfosuccinates. Furthermore, other additives such as antistatic agents, ultraviolet absorbers, pigments, organic fillers, inorganic fillers, lubricants, and antiblocking agents may be mixed within a range that does not impair the effects of the present invention. The aqueous primer coating solution may be applied to the polyester film in a normal coating process, that is, in a biaxially stretched and heat-set polyester film, the film is manufactured and the film is cut and coated. However, this process tends to introduce dirt, dust, etc., and it is desirable to apply the coating in a clean atmosphere for advanced products such as magnetic tapes and floppy disks. From this point of view, coating during the polyester film manufacturing process is preferable. In particular, it is preferable to apply an aqueous primer coating liquid to one or both sides of the polyester film before the crystal orientation is completed during this step. At that time, the solid content concentration of the aqueous primer coating solution is usually 30% by weight or less,
More preferably, it is 10% by weight or less. The amount of coating is 0.5 to 20 g ^per square meter of running film, and more preferably 1 to 10 g.
g is preferred. Any known coating method can be used as the coating method. For example, a roll coating method, a gravure coating method, a roll brushing method, a spray coating, an air knife coating, an impregnation method, a curtain coating method, etc. may be applied alone or in combination. The polyester film coated with the aqueous coating solution is dried and subjected to processes such as stretching and heat setting. For example, vertical 1 coated with water-based primer coating liquid.
The axially stretched polyester film is transversely stretched and heat set using a stenter. During this time, the coating solution dries and further undergoes a crosslinking reaction, forming a continuous film on the film. Heat for the crosslinking reaction is usually supplied by heat during stretching or heat setting. This includes e.g.
200℃ for approx. 10 seconds, 150℃ for approx. 1 minute, 120℃ for approx.
Heating may be performed for 15 minutes at 220° C. for approximately 8 seconds, or heating may be performed under more severe or less severe conditions. Also, apply the coating solution at 100℃ for about 5 seconds.
Just heat it at 110℃ for about 5 seconds and at 90℃ for about 20 seconds. It may also be air-dried. Conditions for oriented crystallization of the polyester film, such as stretching, heat setting, etc., can be carried out under conditions conventionally accumulated in the art. Effects of the invention The polyester film having the primer layer obtained in this way can be used as an ink for cellophane,
It exhibits high adhesion to a wide range of paints such as magnetic paints, gelatin compositions, toner compositions for electrophotography, and chemical matte paints, and also has high adhesion to methyl ethyl ketone, toluene, ethyl acetate, butyl acetate, ethanol, dioxane, tetrahydrofuran, and cyclohexanone. , exhibits excellent solvent resistance to organic solvents such as cyclohexane. Examples Hereinafter, the present invention will be further explained with reference to Examples.
Note that "parts" in the examples mean "parts by weight." Moreover, each characteristic of the film was measured by the following method. 1. Adhesion A coating for evaluation is applied to a primer-coated polyester film, dried at 80°C for 1 minute, then aged at 60°C for 24 hours, and roll coated to an average coating thickness of 2 μm. The resulting coated film was tested using an RCA abrasion tester (RCA
The adhesion is measured by the number of times the adhesive wears under a head load of 50g and holes form on the coated surface. [Adjustment of paint for evaluation] Nitrocellulose as paint thinner
Dissolve RS1/2 [flakes containing 25% isopropanol; manufactured by Daicel Corporation] to prepare a 40wt% solution, add 43.9 parts of this solution, and then add 32.5 parts of polyester resin (Desmofene #1700, manufactured by Bayer).
part, 2.60 parts of chromium dioxide magnetic powder, soybean oil fatty acid (Resion P: manufactured by Riken Vitamin Co., Ltd.) as a dispersant/wetting agent, cationic activator (cationic
1 part, 0.5 part, and 0.8 part of AB: manufactured by Nippon Oil & Fats Co., Ltd.) and squalene (shark liver oil) were put into a ball mill. Methyl ethyl ketone (hereinafter abbreviated as MEK) / cyclohexanone / toluene =
282 parts of a mixed solution of 3/4/3 (weight ratio) is further mixed and sufficiently pulverized to prepare a mother liquor paint (45 wt%). For 50 parts of this mother liquor,
48 parts of an addition reaction product of trimethylolpropane and tolylene diisocyanate (Coronate L: manufactured by Nippon Polyurethane Industries, Ltd.) and 6.25 parts of butyl acetate were added to obtain a magnetic paint for evaluation with a final solid content concentration of 42.75 wt%. Ta. 2 Solvent resistance Drop 5 drops (approximately 0.1 cc) of each of tetrahydrofuran and cyclohexanone on the surface of the primer-coated polyester film, place gauze on top of it, then place a 200 g weight on top, and apply the gauze at approximately 1000 mm/min. Move with speed. After drying at room temperature, interference micrographs of those not treated with tetrahydrofuran and cyclohexanone and those treated with 400x are compared, and the state of surface change of the primer is determined as follows. Those with almost no primer: × Those with almost no change in primer: 〇 Those with slight changes in surface morphology in between: 〇～
△ Those with a considerable change in surface morphology: ×~△ Those with an intermediate change in surface morphology: △ Example 1 Polyurethane aqueous dispersion having a carboxylic acid amine base [manufactured by Toyo Polymer Co., Ltd., trade name: Merci]
585] 78 parts (as non-volatile components), polyoxyethylene nonyl phenyl ether [manufactured by NOF Corporation: trade name NS-240] 10 parts, polyfunctional epoxy compound [Toyo Polymer Co., Ltd.: trade name Merci] AD-C-65〕
Dilute 10 parts and 2 parts of 2,4,6-tris(dimethylaminomethyl)phenol with ion exchange water,
An aqueous primer coating solution having a solid content concentration of 4 parts by weight was prepared. This coating liquid was applied to a biaxially stretched polyethylene terephthalate film using a gravure coating method.
Thereafter, heat treatment was performed for 45 seconds in a drying zone at 140° C. to obtain a primer-coated polyester film laminate with an average coating weight of 50 mg (dry)/m ² . The film laminate had sufficient adhesion to the magnetic paint for evaluation and was able to form a good coated surface without running streaks. Example 2 Polyethylene terephthalate (containing lubricant) with an intrinsic viscosity of 0.65 measured in 0-chlorophenol at 25°C was melt-extruded onto a rotating cooling drum maintained at 20°C to obtain an unstretched film with a thickness of 950 μm, and then machined. After being stretched 3.5 times in the axial direction, a coating solution identical to the coating solution prepared in Example 1 was applied to both sides of the uniaxially stretched film by a kiss coating method. The average coating amount at this time was 50 mg/m ² in terms of solid content. Subsequently, it was stretched 3.9 times in the transverse direction at 105℃, and further
Heat treatment was performed at 210° C. to obtain a biaxially oriented polyester film laminate coated with primer on both sides and having a thickness of 75 μm. Examples 3 and 4 The procedure was carried out in exactly the same manner as in Example 2, except that triglycerol triglycidyl ether (Example 3) or ethylene glycol diglycidyl ether (Example 4) was used instead of the polyfunctional epoxy compound in Example 2. A polyester film laminate was obtained. Examples 5 and 6 The reaction was carried out in exactly the same manner as in Example 2, except that 2-methylimidazole (Example 5) or 2-methyl-4-ethylimidazole (Example 6) was used instead of the reaction catalyst in Example 2. A polyester film laminate was obtained. Example 7 Completely the same as Example 2 except that a polyurethane dispersion containing a carboxylic acid amine base (manufactured by Dainippon Ink Industries, Ltd., trade name: Hydran HW-100) was used instead of the coating solution of Example 2. A polyester film laminate was obtained. Comparative Example 1 Thickness 75μm without primer treatment for comparison
Various evaluations were conducted using polyethylene terephthalate film. Comparative Example 2 Completely the same as Example 2 except that the ratio of aqueous polyurethane resin/aqueous epoxy resin/reaction catalyst/polyoxynonyl phenyl ether in Example 2 was 80 parts/10 parts/0 parts/10 parts. A polyester film laminate was obtained. Table 1 shows the results of evaluating the adhesion and solvent resistance of the polyester film laminates obtained in Examples 1 to 7 and Comparative Examples 1 to 2, as well as the stability of the coating liquid when stored at 40°C for one month. Shown below.

[Table] From Table 1, it is clear that the primer layer of the film laminate of the present invention has excellent performance in solvent resistance and adhesion, and enables uniform and stable coating with excellent coating liquid stability. It is.

Claims (1)

[Claims] 1. On at least one side of the polyester film, (1)
A water-based polyurethane containing at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base is reacted with an epoxy compound having (2) or more epoxy groups in the presence of (3) a reaction accelerating compound. A polyester film laminate with a primer layer. 2. The reaction promoting compound is a tertiary amino group-containing compound,
The laminate according to claim 1, wherein the laminate is at least one compound selected from the group consisting of compounds having a nitrogen-containing ring structure and salts thereof. 3. The laminate according to claim 1, wherein the base of the aqueous polyurethane is an amine base. 4. The laminate according to claim 3, wherein the amine base is a carboxylic acid amine base. 5 At least on one side of the polyester film before crystal orientation is completed, (1) an aqueous polyurethane having at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base, (2) two or more epoxy groups A method for producing a polyester film laminate, comprising applying an aqueous primer coating solution containing an epoxy compound having the following properties and (3) a reaction accelerating compound, followed by drying, stretching, and heat treatment to complete crystal orientation. 6. Claim 5, characterized in that the reaction promoting compound is at least one compound selected from the group consisting of a tertiary amino group-containing compound, a compound having a nitrogen-containing ring structure, and a salt thereof. manufacturing method. 7. The manufacturing method according to claim 5, wherein the base of the aqueous polyurethane is an amine base. 8. The manufacturing method according to claim 7, wherein the amine base is a carboxylic acid amine base.