JPH0253222B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an easily adhesive polyester film. More specifically, a thin layer of a specific primer that improves the adhesion between various coatings and polyester film is applied during the manufacturing process of biaxially oriented polyester film to suppress adhesion between the film surface and the treated surface. In particular, the present invention relates to an easily adhesive polyester film which prevents various troubles during coating processing and obstacles during roll unwinding. The object of the present invention is to apply various coatings applied to base films, such as xerophane inks, magnetic paints, gelatin compositions, offset inks, electrophotographic toners, chemical matte paints, diazo paints, heat-sealable compositions, It has excellent adhesion to inorganic film-forming substances, prevents troubles caused by uneven coating and adhesion caused by static electricity during coating, and is highly resistant to various manufacturing conditions for biaxially oriented polyester. The object of the present invention is to provide an easily adhesive polyester coated with a specific thin layer of primer that can exhibit the effect of imparting easy adhesive properties even when the adhesive is applied. Polyesters polymerized from aromatic dibasic acids or their ester-forming derivatives and diols or their ester-forming derivatives include, for example, polyethylene terephthalate or its copolymers, polyalkylene naphthalates, and even a small proportion of this polymer. Melt and press the blend with other resins,
It is known to form a film. This 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 crystalline oriented, the surface has high cohesiveness and poor receptivity to paints, adhesives, and inks. Therefore, when providing a synthetic resin layer on the surface of a polyester film, in order to strengthen the adhesion between the two, the substrate surface is subjected to corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, or flame treatment to activate the surface and then synthesize it. A means of coating with a resin coating has been applied. However, although these means for activating the surface of a substrate can be expected to improve adhesion to the coating material layer by increasing secondary bonding force due to wetting, the activity thereof decreases over time. Thus, surface activation means are not always satisfactory. As another method for increasing the receptivity of the polyester film substrate surface, an etching method has been proposed in which the surface is swollen or partially dissolved with various agents. This can coat the surface with acid, alkali, or amine aqueous solutions.
Etches the surface by immersing it in chemicals such as trichloroacetic acid or phenols to decompose, dissolve, and relax the crystal orientation near the surface, while at the same time reducing cohesion and improving adhesion with the binder resin. The effect is most reliable, and the adhesion between the base material and the synthetic resin coating layer provided thereon is strong. However, some of the chemicals used in this method are harmful and may be dangerous to handle, and there is a risk that volatile substances from the chemicals may be released into the atmosphere. There are various disadvantages from a practical point of view, such as the need to be careful. As a method similar to this method, there is a method in which a primer layer (undercoat layer) is provided on a substrate in advance, a thin surface layer different from the substrate is formed, and then a desired synthetic resin layer is coated. When forming the undercoat layer, the coating process is generally performed in a process separate from the film forming process, so there is a risk that dust such as dirt and debris may be mixed in during the process. For this reason, it is necessary to maintain the delicate quality of highly processed film products such as audio magnetic tape, video magnetic tape, computer magnetic tape, X-ray photographic film, photographic film for printing, and diazo microfilm. Even if an easily adhesive surface is successfully formed, the base film cannot be used in applications where surface defects are caused by dust. In particular, when finishing a base film into a desired processed product, it would be unreasonable and economically or industrially technically advantageous to provide a primer coating process in order to modify the surface to be highly workable. It can not be said. Therefore, if the process of applying the primer (undercoat) is carried out in an atmosphere that is as dust-free as possible, for example during the process of forming a polyester film, it will be possible to fully support the use of the above-mentioned advanced film processed products. It is desirable to perform in-line subbing processing in such a film forming process. In the prior art, the modification of the polyester film surface to an easily adhesive surface by primer treatment is 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 used during film production, the organic solvent that escapes may contaminate the surrounding environment, cause unfavorable safety and hygiene conditions, and have a negative impact on the film production process, so the use of organic solvents should be kept to a minimum. It should be stopped. 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. Many such primer compositions using water as a solvent have been known, but when in-line subbing treatment is performed using them,
Although it is highly effective for a limited number of topcoat compositions, it is completely ineffective for other types of compositions, and there is no surface receptivity that is sufficiently satisfactory for a wide range of uses. Furthermore, when performing in-line subbing treatment during the film forming process using well-known ethyleneimine-based, amine-based, or epoxy-based primers, blocking phenomenon may occur due to insufficient coating film formation. There are many problems that can occur, such as deterioration of workability, stretching unevenness, coloring, and discoloration of the film, which significantly deteriorate the physical properties and appearance of the film. The present invention was developed as a result of intensive research into preventing blocking, which is incompatible with improving adhesion in the prior art.
This was achieved by discovering a coating liquid composition that allows the formation of a coating layer on a polyester film that has easy adhesion and anti-blocking properties. That is, in the present invention, (A) a polyester resin is applied to the surface of a polyester film before oriented crystallization is completed.
100 parts by weight and (B) 0.1 inorganic substance with an average particle size of 10μ or less
This is a method for producing an easily adhesive biaxially oriented polyester film, which comprises applying an aqueous dispersion containing up to 200 parts by weight, and then subjecting the film to a stretching heat treatment to complete oriented crystallization. The present invention will be explained. In the present invention, the film-forming polyester is a flocculent saturated polyester with a high melting point and high crystallinity synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Examples of such polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, etc., and also include copolymers of these or blends of these with small proportions of other resins. It will be done. The polyester film of the present invention is obtained by melt-extruding the cotton-like saturated polyester resin described above, 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 cm ² /g or more. be. In the present invention, a polyester film before oriented crystallization is an unstretched film obtained by thermally melting the polymer and forming it into a film as it is; Oriented uniaxially stretched film; Biaxially stretched film that is further stretched and oriented at a low magnification in both the vertical and horizontal directions, and finally re-stretched in the vertical or horizontal direction to complete oriented crystallization, etc. This includes: Even if the film is coated with a primer after biaxial stretching and heat setting to complete crystal orientation, the adhesion between the primer layer and the base material (film) will not be sufficient, so the primer surface layer and the top coat in contact with this will not be sufficient. Even if the layer has good adhesion, it lacks adhesion to the base material and satisfactory results cannot be obtained. An embodiment of the present invention consists of applying a specific aqueous liquid to the film surface before the oriented crystallization of the film structure is completed. Therefore, the applied primer layer undergoes a base material stretching process and a heat treatment process, and can provide great adhesion at the interface between the primer layer and the base material layer. Furthermore, it is desirable that the primer layer has excellent adhesion to various coated materials to be processed in the next step. A specific aqueous liquid that can be applied in the present invention is an aqueous dispersion containing (A) 100 parts by weight of a polyester resin and (B) 0.1 to 200 parts by weight of an inorganic substance having an average particle size of 10 μm or less. The polyester resin of component (A) contains sulfonate, carboxylate, polyoxyalkylene glycol, etc. in the molecule. In order to introduce a sulfonate group into the 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
An alkali metal sulfonic acid salt or amine sulfonic acid salt compound such as -K sulfoterephthalic acid or Na sulfosuccinic acid can be used. The polyhydric carboxylic acid or polyhydric alcohol having a sulfonate group is 2 to 60 mol%, preferably 8 to 25 mol% of the total polycarboxylic acid component or polyhydric alcohol component.
occupies If it is less than 2 mol%, the hydrophilicity will be poor, and if it exceeds 60 mol%, the water resistance will be poor, and it will be disadvantageous in the production of the polymer. Other components used as polyvalent carboxylic acids are terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, and pyromellitic acid. , dimer acid, itaconic acid and the like. Polyhydric alcohol components include ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylylene glycol, dimethylolpropionic acid, glycerin, and trimethylol. propane,
Examples include poly(ethylene oxide) glycol and poly(tetramethylene oxide) glycol. In addition to these components, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-(β-hydroxyethoxy)benzoic acid can also be used. This polyester resin is synthesized from the above-mentioned polyhydric carboxylic acid or its ester-forming derivative and the above-mentioned polyhydric alcohol or its ester-forming derivative by a known method. To introduce a carboxylate group, trimellitic acid, pyromellitic acid,
These monomers before polymerization or the resulting polymer are reacted with an alkali metal compound, ammonia, an amino compound, etc. using trimesic acid or the like or dimethylolpropionic acid or the like. Any inorganic substance can be selected as the component (B), but silicon dioxide, aluminum trioxide, magnesium carbonate, calcium oxide, magnesium oxide, lithium oxide, etc. are preferable. This mineral has a particle size of
Choose one with an average particle size of 10μ or less. If the primary particle size exceeds 10μ, film homogeneity, film formability, etc. will be poor. The amount added is 0.1 to 200 parts by weight, preferably 0.5 to 200 parts by weight, based on 100 parts by weight of the polyester resin (A).
It is 200 parts by weight. An aqueous dispersion can be prepared from the components (A) and (B) by any method. Regarding the polyester resin of component (A), there are two methods: completely dissolving the resin in water, and creating an emulsion, dispersion, or suspension. In any case, all methods using water as a medium for forming the primer layer are included. In preparing the aqueous liquid, water may be mixed with a small amount of other medium such as an organic solvent. The method for making an aqueous liquid is (1) dissolving the polyester resin in water; (2) making an emulsion or suspension by using an emulsifier, dispersant, suspension stabilizer, etc. together with the polyester resin and water; 3) After dissolving the polyester resin in a medium other than water, it is added to water to form an emulsion or suspension and the medium is removed; (4) The polyester resin is heated and melted and dispersed in contact with water or other medium. (5) Preparing fine particles of polyester resin and dispersing the particles in water to stabilize them. A method of preparing an aqueous dispersion of the inorganic substance of the component (B) separately and mixing this with the aqueous solution of the polyester resin of the component (A), a method of dispersing the component (B) and the component (A) in water at the same time, etc. They can be blended by any method. The aqueous liquid has an arbitrary solid content concentration (preferably 0.1~
15 wt%), and a required amount of surfactant such as an anionic surfactant or nonionic surfactant may be added during coating. As an effective surfactant, the surface tension of aqueous liquid is 40dyne/cm.
Many known surfactants can be used to promote wetting of the polyester film. One example is polyoxyethylene alkyl phenyl ether,
Examples include polyoxyethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate, alkyl sulfonate, alkyl sulfosuccinate, quaternary ammonium chloride, and alkylamine hydrochloride. The coating may be thick enough to completely cover the surface layer of the polyester film. When forming the primer layer, it is essential that the polyester film be applied before the crystal orientation is completed. At this time, any known coating method can be used to apply the aqueous polyester dispersion onto the surface of the polyester film before stretching and orientation. For example, roll coating, gravure coating, roll plating, spray coating, air knife coating, impregnation, curtain coating, and the like may be applied independently or in combination. The coating process is applied to the surface layer of the base material immediately after melt-extruding the polymer and casting the unstretched film, or immediately after stretching in either the vertical or horizontal direction. In order to form a primer layer and at least exhibit its effectiveness, it is necessary to dry the paint film just before undergoing heat setting, and then heat the paint film for at least 2 seconds at a temperature of at least 120°C. preferable. In addition, the primer layer can be formed by taking an unstretched film or a uniaxially stretched film in advance, coating and drying it outside the film production line, and then performing biaxially or uniaxially stretching and heat setting. From the viewpoint of primer treatment effect and economy, it is preferable to apply the primer consistently in the film production line. Although the coated easily adhesive film of the present invention has no blocking phenomenon, it can be used in cellophane inks, magnetic paints, gelatin compositions, linseed oil-based offset inks, electrophotographic toner compositions, chemical matte paints, It exhibits extremely wide adhesion performance for diazo paints, heat-sealable compositions, inorganic coating-forming substances, metal vapor deposition substances, etc. Hereinafter, a detailed explanation will be given with reference to examples. Note that the measurement items in the examples were measured by the following methods. 1 Adhesion A polyester film treated with a primer was coated with various top coats under specified conditions, and Scotch Tape No. 600 (manufactured by Three M Company), width 19.4 mm and length 8 cm, was adhered without air bubbles. The top was leveled with a manual load roll as described in JIS C2701 (1975), and the 5cm gap between the laminated parts was covered with Tensilon UM- manufactured by Toyo Baldwin Co., Ltd.
This sample is peeled in a T-shape using a head speed of 300 mm/min, the peel strength at this time is determined, and this is divided by the tape width to determine g/cm. In addition, in T-peeling, the laminate was placed with the tape side facing down, and the distance between the take-off chucks was 5 cm. 2 Surface slipperiness The temperature of the primer-coated and non-primer-coated surfaces was measured. The static friction coefficient is measured at 20°C and 60% RH using a Slippery measurement tester manufactured by Toyo Tester. 3. Blocking resistance Two films (15 cm x 10 cm) were placed on top of each other, treated and non-treated, and a pressure of 2 kg/cm ² was applied for 24 hours in an atmosphere of 60°C x 75% RH.
A chrome-plated rod with a smooth surface and a diameter of 5 mm was sandwiched between two films in accordance with ASTM-D-1893, and the two films were peeled off at a speed of 100 mm/min to determine the peeling force. If this value exceeds 100 g/10 cm, troubles will occur more frequently during film processing. 4 Haze (cloudiness) Total transmittance (Tt) was measured using NDH-2 model manufactured by Nippon Senzo Kogei Co., Ltd. as an integrating sphere type light transmission measurement device.
The diffused transmittance (Td) was determined, and the haze value was determined using Td/Tt×100. In addition, various top paints used in the adhesive evaluation were prepared in the following manner. 1 Magnetic paint Nitrocellulose in Lutzker thinner for paint
Dissolve RS1/2 [manufactured by Flakes Tycel Co., Ltd. containing 25% isopropanol] to prepare a 40wt% solution, add 43.9 parts of this solution, and then add 325 parts of polyester resin (Desmofene #1700 manufactured by Bayer) and chromium dioxide. Magnetic powder 2.60gr, soybean oil fatty acid (Rexion P; Riken Vitamin as a dispersant/wetting agent)
1 part, 0.5 part, and 0.8 parts of squalene (shark liver oil), a cationic activator (Cation AB, manufactured by Nippon Oil & Fats Co., Ltd.), and a cationic activator (manufactured by Cation AB Nippon Oil & Fats Co., Ltd.) were placed in a ball mill. Methyl ethyl ketone (hereinafter abbreviated as MEK)/cyclohexanone/toluene = 3/4/
Further, 282 parts of a mixed solution consisting of
%). To 50 parts of this mother liquor, 48 parts of an addition reaction product of trimethylolpropane and toluleine diisocyanate (Coronate L: manufactured by Nippon Polyurethane Industries, Ltd.) was added to 6.25 parts of butyl acetate, resulting in a final evaluation of 42.75 wt%. A magnetic paint for use was obtained. 2 Gravure printing ink Commercially available gravure ink for cellophane printing whose main binders are nitrocellulose and rosin oil: CLS-709 white (manufactured by Dainippon Ink Co., Ltd.)
2 parts of the stock solution was diluted with 1 part of a mixed solvent of toluene/ethyl acetate/methyl ethyl ketone = 1/1/1 to prepare a paint for evaluation. 3 Gelatin paint Add 10 parts of photographic gelatin (Nitta Gelatin), 1 part of saponin, and 539 parts of distilled water, solid content concentration 2
% gelatin paint for simple evaluation was obtained. The above-mentioned three types of paints were applied to a biaxial polyester film that had completed the crystal orientation, and the magnetic paint was dried at 80°C for 1 minute, and then rolled so that the coating thickness after aging at 60°C for 24 hours was 5μ on average. 80 for coating and gravure printing ink
Gravure coating is applied so that the coating thickness after drying for 14 minutes at 110℃ is 1.2μ on average, and gelatin paint is roll coated so that the coating thickness after drying for 2 minutes at 110℃ is 0.6μ on average, to ensure the adhesion of these top coats. The properties were measured and the results shown in Table 1 were obtained.

[Table] Example 1 (a) Preparation of polyester aqueous dispersion Terephthalic acid (80 mol%)-5Na-sulfoisophthalic acid (20 mol%)-ethylene glycol copolyester (molecular weight 6200) 60 g, average particle size 30 mμ 30 g of silicon dioxide and 9 g of nonionic surfactant polyoxyethylene nonyl phenyl ether [HLB12.8 Nonion NS208.5: manufactured by NOF Corporation] were heated, dissolved and dispersed in 3000 g of ion-exchanged water, and then cooled. The coating solution was prepared. (b) Production of easily adhesive film Polyethylene terephthalate, which has a polymer intrinsic viscosity of 0.65 measured in o-chlorophenol at 25°C, was melt-extruded onto a rotating drum maintained at about 20°C to obtain an unstretched film of 158μ (microns). Next, this was stretched 3.5 times in the machine direction, and then the coating solution prepared in (a) was applied to one side of the uniaxially stretched film by a kiss coating method. Then 98
It passed through a preheating zone at 105°C and was stretched 3.9 times in the transverse direction. Subsequently, heat treatment was performed at 200° C. for 4.2 seconds to obtain a biaxially stretched primer-coated polyester film with an average coating weight of 100 mg/m ² and a thickness of 12.2 μm. Table 2 shows the results of measuring the adhesion, surface smoothness, blocking resistance, and haze of the treated surface of this film.

[Table] Example 2 In (a) of Example 1, instead of terephthalic acid (80 mol%) -5Na sulfoisophthalic acid (20 mol%) -ethylene glycol copolyester, terephthalic acid (77 mol%) -5Na- Table 3 shows the evaluation results of the primer-treated film obtained in the same manner as in Example 1 except that sulfoisophthalic acid (23 mol %)-ethylene glycol copolymer (molecular weight 12,000) was used. Example 3 The evaluation results of the film of the present invention obtained in the same manner as in Example 1 except that the amount of copolymerized polyester in (a) of Example 1 was changed from 60 g to 35 g were evaluated in the third example.
Shown in the table. Example 4 Table 3 shows the measurement results of the film of the present invention obtained in the same manner as in Example 1 except that the amount of copolyester was changed from 60 g to 45 g in (a) of Example 1. Example 5 Table 3 shows the evaluation results of a film obtained in the same manner as in Example 1 except that the amount of copolymerized polyester in (a) of Example 1 was changed from 60 g to 55 g. Example 6 Table 3 shows the measurement results of a film obtained in the same manner as in Example 1 except that the amount of copolymerized polyester in (a) of Example 1 was changed from 60 g to 70 g. Example 7 Table 3 shows the measurement results of a film obtained in the same manner as in Example 1 except that the amount of copolymerized polyester in (a) of Example 1 was changed from 60 g to 90 g. Example 8 Table 3 shows the evaluation results of the film of the present invention obtained in the same manner as in Example 1 except that the amount of copolymerized polyester in (a) of Example 1 was changed from 60 g to 120 g. Example 9 Table 3 shows the measurement results of a polyester film obtained in the same manner as in Example 1 except that the amount of copolymerized polyester in (a) of Example 1 was changed from 60 g to 140 g. Example 10 Table 3 shows the measurement results of a film obtained in the same manner as in Example 1 except that the amount of nonionic surfactant in (a) of Example 1 was changed from 9 g to 6 g. Example 11 The measurement results obtained in the same manner as in Example 1 except that instead of heat treatment at 200 °C for 4.2 seconds in (b) of Example 1, heat treatment was performed at 185 °C for 8 seconds, the measurement results were obtained in the same manner as in Example 1.
Shown in the table.

[Table] Examples 11 to 16 In the preparation of the polyester aqueous dispersion in Example 1(a), except that predetermined amounts of various inorganic substances with various particle sizes were used instead of 30 g of silicon dioxide with an average particle size of 30 mμ. Table 4 shows the measurement results for the film obtained in the same manner as in Example 1.

【table】

Claims (1)

[Claims] 1. Add (A) 100 parts by weight of polyester resin and (B) to the surface of the polyester film before oriented crystallization is completed.
Inorganic substances with an average particle size of 10μ (microns) or less 0.1~
200 parts by weight of an aqueous dispersion, and then subjecting the film to a stretching heat treatment to complete oriented crystallization.