JPH0367625B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Field of Application> The present invention relates to an easily adhesive polyester film and a method for producing the same, and more specifically to highly processed products such as audio magnetic tape, video magnetic tape, computer magnetic tape,
The present invention relates to a polyester film having excellent adhesiveness and blocking resistance, useful as a base material for floppy disks, X-ray photographic films, telephone cards, membranes, diazo microfilms, etc., 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 of these with small proportions of other resins, to form films. be. 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 its surface is highly crystallized, its surface cohesiveness is high;
For example, it has poor adhesion to paints, adhesives, inks, etc. Therefore, physical treatments such as corona treatment, ultraviolet ray treatment, plasma treatment, EB treatment, or flame treatment, or chemical treatments such as alkali, amine aqueous solution, trichloroacetic acid, phenols, etc. are known as methods to improve this adhesion. It is being However, these methods have practical disadvantages such as deterioration of adhesive strength over time and contamination of the working environment due to volatilization of chemicals. Another known method is to apply an easily adhesive coating agent to the surface of the film in a process other than the usual polyester film forming process to form a primer layer. However, with this method, organic solvents are usually used as coating solvents, and the coating atmosphere is not sufficiently clean, resulting in frequent surface defects on processed products due to dust adhesion, or environmental pollution caused by organic solvents. There are safety and hygiene problems such as deterioration. By the way, if this primer treatment is performed during the polyester film forming process using a water-based coating agent, the film can be formed in a clean environment without dust adhesion, and because it is a water-based solvent, there is no risk of explosion or environmental deterioration. It is advantageous in terms of performance, economy, and safety. Because of these advantages, it has been proposed to use water-soluble or water-dispersible polyester resins or acrylic resins as primers (Japanese Patent Application Laid-open No. 43017/1983, Japanese Patent Publication No. 10243/1973, -19786, JP-A-52-19787, etc.). but,
The above-mentioned polyester resin has the disadvantage of easily causing blocking when the film is wound into a roll, and the above-mentioned acrylic resin has the disadvantage of poor adhesion with the film, mechanical strength, and adhesion with the magnetic layer. be. In order to improve these drawbacks, it has been proposed to use a mixture of the above polyester resin and the above acrylic resin (Japanese Patent Laid-Open No.
No. 58-124651), but the improvement of these drawbacks cannot be said to be sufficient. <Object of the invention> The object of the invention is to provide various coatings applied to polyester films, such as offset inks,
Gravure ink, silk screen ink, UV
Ink, magnetic paint, zentin composition, adhesive, electrophotographic toner, chemical matte paint, diazo paint, hard coat paint, chemical matte paint, diazo paint, hard coat paint, UV paint, heat-sealable composition, inorganic material The object of the present invention is to provide an easily adhesive polyester film having excellent adhesion to film-forming substances and the like and having a non-tacky primer layer. Another object of the present invention is to provide a preferred method for producing such an easily adhesive polyester film. <Structure/Effects of the Invention> According to the present invention, (1) at least one side of the polyester film,
An easily adhesive polyester film comprising a primer layer of an aqueous graft polymer in which the trunk polymer is an acrylic polymer and the branch polymers are polyester, and (2) on at least one side of the polyester film before crystal orientation is completed, An easily adhesive polyester characterized by applying an aqueous primer solution containing an aqueous graft polymer in which the trunk polymer is an acrylic polymer and the branch polymers are polyester, followed by drying, stretching, and heat treatment to complete crystal orientation. This is achieved by a film manufacturing method. In the present invention, the polyester constituting the polyester film 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 isotalate, polybutylene terephthalate,
Examples include poly(1,4-cyclohexylene dimethylene terephthalate) and polyethylene-2,6-naphthalene dicarboxylate, and also include copolymers of these or blends of these with small proportions 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 has crystal orientation to such an extent that the heat of crystal fusion measured by a differential scanning calorimeter in a nitrogen stream [at a heating rate of 10°C/min] is usually 4 cal/g or more. Preferably. In the present invention, a 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; an unstretched film oriented in either the vertical direction or the horizontal direction. Uniaxially stretched film; furthermore, one that has been stretched and oriented at a low magnification in both the vertical and horizontal directions (biaxially stretched film before being finally re-stretched in the vertical or horizontal direction to complete oriented crystallization), etc. This includes: The aqueous primer liquid used in the present invention contains an aqueous graft polymer in which the trunk polymer is an acrylic polymer and the branch polymers are polyesters. Examples of monomers of the acrylic polymer that will become the backbone polymer of this aqueous graft polymer include alkyl acrylate, alkyl methacrylate (alkyl groups include methyl group, ethyl group, n-
propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group, etc.): 2-hydroxyethyleacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2
- Hydroxy-containing monomers such as hydroxypropyl acrylate, 2-hydroxypropyl methacrylate; acrylamide, methacrylamide,
N-methylmethacrylamide, N-methylacrylamide, N-methylolacrylamide, N-
Amide group-containing monomers such as methylolmethacrylamide, N,N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide; N,N-diethylaminoethyl acrylate, N,N-diethylamino Amino group-containing monomers such as ethyl methacrylate; Epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; acrylic acid, methacrylic acid and their salts (sodium salts, potassium salts,
Examples include monomers containing carboxyl groups or salts thereof such as ammonium salts, etc. These can be used in combination with various monomers. Other monomers include epoxy group-containing monomers such as acrylic glycidyl ether; styrene sulfonic acid;
Monomers containing sulfonic acid groups or their salts such as vinyl sulfonic acid and their salts (sodium salt, potassium salt, ammonium salt, etc.); crotonic acid, itaconic acid, maleic acid, fumaric acid and their salts (sodium salt, potassium salt, ammonium salt, etc.); monomers containing carboxyl groups or their salts such as potassium salts, ammonium salts, etc.; monomers containing acid anhydrides such as maleic anhydride and itaconic anhydride; vinyl isocyanate, allyl isocyanate, styrene,
vinyl methyl ether, vinyl ethyl ether,
Vinyl tris alkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile,
Examples include alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, vinyl chloride, and the like. The above-mentioned monomers can be copolymerized using one type or two or more types, but from the viewpoints of imparting hydrophilicity to the acrylic polymer, dispersion stability of the aqueous liquid, adhesion to the polyester film, etc. , an amide group, a carboxyl group, or a salt thereof (sodium salt, potassium salt, ammonium salt, etc.) is preferred. This acrylic polymer can be produced by a known method. The polyester which becomes the branch polymer of the aqueous graft polymer is a substantially linear polymer synthesized from a polybasic acid or its ester-forming derivative and a polyol or its ester-forming derivative. Polybasic acid components of this polymer include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 1,4-
Examples include cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, and dimer acid. Two or more types of these can be used. Along with these components, a small proportion of hydroxycarboxylic acids (e.g. P-hydroxybenzoic acid, P-(β-hydroxyethoxy)benzoic acid, ε-caproic acid, etc.) or unsaturated carboxylic acids (e.g. maleic acid, fumaric acid, itaconic acid, etc.) etc.) can be used. The proportion of hydroxycarboxylic acid components and unsaturated carboxylic acid components is at most 10
It is preferably mol% mole, more preferably 5 mol% or less. In addition, the polyol components include ethylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4
Examples include -cyclohexanedimethanol, xylylene glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, poly(ethylene oxide) glycol, poly(tetramethylene oxide) glycol, and the like. Two or more types of these can be used. This polyester is preferably an aqueous polymer; for example, one containing a compound having a hydrophilic group such as an organic sulfonate, a carboxylate, diethylene glycol, polyalkylene ether glycol, etc. is advantageous for making an aqueous dispersion and is therefore preferred. . Introducing this carboxylic acid salt usually uses a trifunctional or higher-functional carboxylic acid, but the carboxylic acid causes branching during the polymerization process and tends to cause gelation, so it is desirable to keep the copolymerization ratio small. In this respect, the introduction of hydrophilic groups using sulfonate salts, diethylene glycol, polyalkylene ether glycol, etc. does not have these problems and is more advantageous. In order to introduce a sulfonate group into the polyester molecule, for example, 5-Na sulfoisophthalic acid, 5-ammonium sulfoisophthalic acid, 4-
Na sulfoisophthalic acid, 4-methylammonium sulfoisophthalic acid, 2-Na sulfoterephthalic acid, 5-K sulfoisophthalic acid, 4-K sulfoisophthalic acid, 2-K sulfoterephthalic acid, Na
It is preferable to use a sulfonic acid alkali metal salt type compound such as sulfosuccinic acid or a sulfonic acid amine salt type compound. The polyhydric carboxylic acid or polyhydric alcohol having a sulfonate group preferably accounts for 0.5 to 20 mol%, more preferably 1 to 8 mol%, of the total polycarboxylic acid component or polyhydric alcohol component. In addition, in order to introduce a carboxylic acid group into the polyester molecule, for example, trimellitic anhydride,
Compounds such as trimellitic acid, pyromellitic anhydride, pyromellitic acid, trimesic acid, cyclobutanetetracarboxylic acid, and dimethylolpropionic acid can be used. Further, a carboxylic acid salt can be obtained by neutralizing a carboxylic acid with an amino compound, ammonia, an alkali metal, or the like. When introducing a hydrophilic group-containing compound into a polyester molecule, various known methods can be employed. To further explain the case of introducing a carboxylate or organic sulfonate group into a polymer molecule, for example, polyester is synthesized using a compound having a carboxylate or organic sulfonate group in the molecule as one of the starting materials. A method in which a polyester is synthesized using a compound having three or more carboxylic acid groups in the molecule as one of the starting materials, and then free carboxyl groups in the polyester are neutralized in a medium with ammonia, amine, alkali metal compound, etc. let There are other methods. To further explain the method, for example, trimellitic anhydride is added to one of the polyester raw materials.
There is a method in which polyester is used as a component to prepare a polyester having free carboxyl groups in the side chain, and after the reaction is completed, aqueous ammonia is added to neutralize it. The aqueous graft polymer in the present invention can be produced, for example, by using an acrylic polymer as a trunk polymer and grafting polyester thereon as a branch polymer, but this manufacturing method is not particularly limited. Some examples of this manufacturing method include a method in which an unsaturated group is introduced at one end of polyester and copolymerized with an acrylic monomer, and a method in which functional groups such as carboxyl groups, hydroxyl groups, and methylol groups are added to the side chains of the acrylic polymer. An epoxy group, an isocyanate group, which is introduced and reacts with the above functional group at one end,
There is a method using a polymer reaction in which polyester into which hydroxyl groups, methylol groups, etc. have been introduced is reacted.
The molecular weight of the backbone polymer in the aqueous graft polymer is preferably 5,000 to 200,000, more preferably 10,000 to 100,000,
In addition, the molecular weight of the branch polymer is 500 to 50,000, and even
1,000 to 10,000 is preferable. The weight ratio of the trunk polymer to the branch polymer is 5:95 to 95:5, or even
10:90 to 90:10 is preferred. In the present invention, the aqueous primer liquid is obtained by dissolving or dispersing the above-mentioned aqueous graft polymer in an aqueous medium, but this aqueous primer liquid contains some organic matter as long as it does not affect the aqueous graft polymer or other additives. It may contain a solvent.
Any method can be used to produce such an aqueous primer solution, such as a method of synthesizing an aqueous graft polymer in an organic solvent and then replacing part or all of the organic solvent with an aqueous medium; Preferred examples include a method in which an aqueous solution or emulsion is directly obtained by conducting a chemical reaction. A surfactant such as an anionic surfactant, a cationic surfactant, or a nonionic surfactant can be added to the aqueous primer liquid. As such surfactants, the surface tension after aqueous application is
It is preferable to use a material that can drop to 40 dyne/cm or less and promotes wetting to polyester film, such as polyoxyethylene alkyl phenyl ether,
Polyoxyethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester,
Examples include fatty acid soaps, alkyl sulfates, alkyl sulfonates, alkyl sulfosuccinates, quaternary ammonium chlorides, alkylamine-hydrochloric acids, and the like. 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 solution may be applied to the polyester film in a normal coating process, that is, in a process in which the biaxially stretched and heat-set polyester film is coated separately from the film manufacturing process. However, this process tends to involve dirt, dust, etc.
For advanced products such as magnetic tapes and floppy disks, it is desirable to apply in a clean atmosphere. From this point of view, coating during the polyester film manufacturing process is preferable. In particular, it is preferable to apply an aqueous primer liquid to one or both sides of the polyester film before the crystal orientation is completed during this step. In this case, the solid content concentration of the aqueous primer liquid is usually 30% by weight or less, more preferably 10% by weight or less. The amount of coating is ^1m2 of the moving film.
It is preferably 0.5 to 20 g, more preferably 1 to 10 g. 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 method, an air knife coating method, an impregnation method, a curtain coating method, etc. may be applied alone or in combination. The polyester film coated with the aqueous primer solution and before crystal orientation is completed is dried and subjected to processes such as stretching and heat setting. For example, a longitudinally uniaxially stretched polyester film coated with an aqueous primer solution is guided into a stenter, where it is laterally stretched and heat-set. During this time, the coating solution dries and forms a continuous film on the film. Drying is preferably carried out before or during stretching. 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. The polyester film having the primer layer obtained in this manner solves the problems when using conventional water-based polyester resins or acrylic resins, as well as the problems when using a blend of these resins. Ink for cellophane, magnetic paint, gelatin composition, toner composition for electrophotography, chemical matte paint, diazo paint,
It exhibits high adhesion to a wide variety of paints such as UV inks, and exhibits good blocking resistance without stickiness. <Examples> The present invention will be further explained below 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 Apply UV Shine Beni T manufactured by Moroboshi Ink Co., Ltd. to a thickness of 4 μm to polyester film or primer-treated polyester film, irradiate it with ultraviolet rays for 5 minutes using a 1.5 KW ultra-high pressure mercury lamp, and then apply Scotch Tape No. 600. (manufactured by 3M) 19.4 mm wide and 15 cm long with adhesive so as not to create air bubbles, and then apply JIS C2701
(1975), the tape was smoothed and brought into close contact with a manual load roll, and then cut out to the width of the tape. Rapidly peel off this sample with the polyester film facing up and observe how the UV ink is peeled off. Most of the UV ink has transferred to the adhesive tape × Half of the UV ink remains on the polyester film △ All of the UV ink remains on the polyester film 〇2 Blocking property The primer-coated sides of the polyester film are placed together. Then cut into 10cm x 15cm squares, and add 55
A load of 6 kg/cm ² was applied for 17 hours in an atmosphere of ℃ x 80% RH, and then the strength of this 10 cm wide peel was measured. The peeling speed at this time was 100 mm/min. Example 1 The acid component consists of terephthalic acid (49 mol%), isophthalic acid (49 mol%) and 5-sodium sulfoisophthalic acid (2 mol%), and the glycol component consists of ethylene glycol (50 mol%) and neopentyl. Polyester (molecular weight
5000), and radically polymerized 30 parts of this polyester with 35 parts of methylacrylamide, 32 parts of ethyl acrylate, and 3 parts of methacrylamide,
An acrylic polymer-polyester graft polymer (molecular weight 60,000) was obtained. 9 parts of this polymer and
After gradually adding 490 parts of water to a solution in which 1 part of a nonionic surfactant of HLB 12.8 and 90 parts of tetrahydrofuran was dissolved, the tetrahydrofuran was distilled under heating.
The solvent was removed to obtain an aqueous primer solution. Polyethylene terephthalate with an intrinsic viscosity of 0.65, measured in o-chlorophenol at 25°C, was melt extruded onto a rotating cooling drum maintained at 20°C to obtain a thickness.
An unstretched film of 950 μm was obtained, then stretched 3.5 times in the machine axis direction, and then the above primer solution was applied to both sides of the uniaxially stretched film by a kiss coating method. The average application amount at this time is 50mg/solid content.
It was ^m2 . Subsequently, the film was stretched 3.9 times in the transverse direction at 105°C and further heat-treated at 210°C to obtain a polyester film coated with primer on both sides and having a thickness of 75 μm. Example 2 Acrylic polymer (molecular weight 3 10,000 parts), the acid components are terephthalic acid (80 mol%) and isophthalic acid (17 mol%).
and 5-sodium sulfoisophthalic acid (3 mol%), and the glycol components are ethylene glycol (50 mol%) and 1,4-butanediol (50% mol%), and one end is made by reacting a polyester with triene diisocyanate. A graft polymer was obtained by polymerizing 50 parts of isocyanate polyester (molecular weight 5000). A primer-coated polyester film was obtained in the same manner as in Example 1 except that this graft polymer was used as the aqueous graft polymer. Comparative Example 1 For comparison, various evaluations were conducted using a 75 μm thick polyester film that was not subjected to primer treatment. Comparative Example 2 The acid component consists of terephthalic acid (49 mol%), isophthalic acid (49 mol%) and 5-sodium sulfoisophthalic acid (2 mol%), and the glycol component consists of ethylene glycol (50 mol%) and neopentyl glycol. A primer solution was obtained in the same manner as in Example 2, except that a blend of polyester (50 mol %) and the acrylic polymer of Example 2 was used. A primer-coated polyester film was obtained in exactly the same manner as in Example 1 except for using this primer solution. Table 1 shows the performance of the polyester films of Examples 1 and 2 and Comparative Examples 1 and 2.

[Table] As is clear from Table 1, the primer-coated polyester film of the graft polymer of the present invention has excellent properties.

Claims (1)

[Claims] 1. On at least one side of the polyester film,
An easily adhesive polyester film comprising a primer layer of an aqueous graft polymer in which the trunk polymer is an acrylic polymer and the branch polymers are polyester. 2. An aqueous primer solution containing an aqueous graft polymer in which the trunk polymer is an acrylic polymer and the branch polymers are polyester is applied to at least one side of the polyester film before crystal orientation is completed, and then dried, stretched, and heat treated. A method for producing an easily adhesive polyester film, characterized in that crystal orientation is completed by