JPS6337824B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an easily adhesive polyester film. More specifically, the present invention relates to an easily adhesive polyester film obtained by coating the surface of a polyester film with a specific primer coating layer and then subjecting this coating layer to electric discharge treatment, and a method for producing the same. The object of the present invention is to apply various coatings applied to base films, such as cellophane inks, magnetic paints, gelatin compositions, offset inks, electrophotographic toners, chemical matte paints, diazo paints, heat-sealable compositions, An object of the present invention is to provide an easily adhesive polyester film coated with a specific primer thin layer having excellent adhesion to inorganic film-forming substances, etc., and a method for producing the same. 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 extrusion of a 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, prior art surface activation means are not always satisfactory. On the other hand, 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 chemicals. 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. Another method is to provide a primer layer (undercoat layer) on the substrate in advance, form a thin surface layer different from the substrate, and then coat it with a desired synthetic resin layer. When forming the undercoat layer, the coating process is generally performed in a process different 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, in applications where the quality of highly processed film products (e.g. audio magnetic tape, video magnetic tape, computer magnetic tape, X-ray photographic film, photographic film for printing) must be maintained, is difficult. As an improvement to this method, primer (undercoat)
If the process is carried out in an atmosphere that does not generate dust (for example, during the polyester film production process), it can be used for the aforementioned advanced film processing products, and in-line subbing processing in the film production process can be performed. It is desirable to do so. Therefore, we investigated an adhesion-promoting treatment using a combination of modification means by primer treatment on the surface of polyester film and activation means such as flame treatment and corona discharge treatment. It has been discovered that a synergistic effect on adhesive properties occurs when Moreover, in the case of the present invention, it has been found that the disadvantages of primer processing such as blocking phenomenon, coloring, and discoloration that are often seen with conventionally known ethyleneimine-based, amine-based, and epoxy-based primers do not occur. . The present inventor has developed a coating layer of water-based polyurethane, polyester resin, or polyacrylic resin with a high melting point.
It has been discovered that a polyester film, which is coated on the surface of a highly crystalline polyester film and then subjected to electrical discharge treatment to further increase surface activity, exhibits adhesive properties not seen in conventional technology. . That is, the present invention consists of (1) a polyester film and a coating layer of water-based polyurethane, polyester resin, or acrylic resin coated on the surface of the film (however, it does not contain a swelling agent for the film); An easily adhesive polyester film whose layers are subjected to electrical discharge treatment: and (2) an aqueous solution of water-based polyurethane, polyester resin, or acrylic resin (however, it does not contain a swelling agent for the film) is applied to the surface of the polyester film. , drying, and then subjecting to an electric discharge treatment. The present invention will be explained. In the present invention, the film-forming polyester is a linear 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 above-mentioned linear saturated polyester resin, forming it into a film by a conventional method, and giving it oriented crystallinity and crystallization by heat treatment. 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. . The film used in the present invention is preferably biaxially stretched and heat-set. The coating layer coated on at least one surface of the polyester film is made of water-based polyester resin, urethane resin, or acrylic resin. This coating is applied to the surface of the film to a thickness of about 0.01 to 10 μ (microns) (basis weight of about 0.02 to 20 g/m ² as solid content). Examples of aqueous polyester resins include polymers having polyethylene glycol units, alkali metal sulfonate groups, alkali metal carboxylate groups, ammonium carboxylate groups, etc. in the molecule. Examples include terephthalic acid-isophthalic acid-5Na sulfoisophthalic acid-ethylene glycol copolymer. Examples of the water-based polyurethane resin include a mixture of polyethylene glycol-toluylene diisocyanate-1,4-butanediol-hexamethylene diisocyanate-sodium acrylate/ethylenediamine adduct copolymer and a polyethylene glycol-toluylene diisocyanate-ε-caprolactam reaction product. can be mentioned. As a water-based acrylic resin,
Examples include methyl methacrylate-ethyl acrylate-2-hydroxyethyl acrylate-ammonium acrylate copolymer. These resins can form a primer layer in the form of an aqueous liquid. Aqueous liquids use water as a homogeneous or heterogeneous medium, and include those completely dissolved in water, emulsions, dispersions, and suspensions. All methods of application that use water as a medium for forming a primer layer are applicable to the present invention. In preparing the aqueous liquid, water may be mixed with a small amount of other medium such as an organic solvent. The aqueous liquid has any concentration, preferably 0.1-15wt%
During coating, a required amount of surfactant such as an anionic surfactant or a nonionic surfactant may be added. An effective surfactant is one that promotes wetting of the polyester film by reducing the surface tension of the aqueous liquid to 40 dyne/cm or less, and many known surfactants can be used. Examples include polyoxyethylene alkyl phenyl ether, 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, alkyl Examples include amine hydrochloride. The coating should be thick enough to completely cover the surface layer of the polyester film (approximately
0.02μ or more) is sufficient. Any known coating method can be used to apply the aqueous resin liquid to the surface of the polyester film. Coating methods that can be used in the present invention include, for example, a roll coating method, a gravure coating method, a roll plush method, a spray coating, an air knife coating, an impregnation method, a curtain coating method, etc., independently or in combination. The primer layer is applied to a polyester film such as an unstretched film, a uniaxially stretched film, or a biaxially stretched film, and if necessary, further uniaxially or biaxially stretched. The heat treatment of the film and the drying of the coating film can be carried out simultaneously or separately in arbitrary steps. The film coated with the primer layer is then subjected to electrical discharge treatment. At least one surface of the film coated with the primer layer has a film surface area (1
It is preferable to perform the discharge treatment with a discharge power amount of 50 to 50,000 joules per m ² ). Electric discharge machining in the present invention refers to a processing method in which a film is exposed to an atmosphere that generates electrical discharge between electrodes. Examples of the discharge treatment include corona discharge treatment, glow discharge treatment, and spark discharge treatment. In the case of corona discharge treatment, 50Hz or higher, especially
Using an alternating current of 1 KHz or higher allows for uniform treatment. It is usually best to use an alternating current of 5 to 200 KHz.
Further, the atmosphere for the discharge treatment can be the atmosphere at normal pressure, but it is also possible to use a gas other than air and perform the treatment under reduced pressure. The discharge treatment time should be about 0.001 to 10 seconds, as it is necessary to be careful not to damage the film surface significantly and to prevent the film from shrinking due to heating during discharge. The coated electrical discharge treated easily adhesive film of the present invention can be applied to cellophane inks, magnetic paints, gelatin compositions, linseed oil-based offset inks, electrophotographic toner compositions, chemical matte paints, diazo paints,
It exhibits extremely wide-ranging adhesion performance for heat-sealable compositions, inorganic coating-forming substances, and metal vapor deposition substances. Hereinafter, a detailed explanation will be given with reference to examples. In addition, the measurement items in the examples were measured by the following method. 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 G2701 (1975), and a 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-up 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 sliver measuring 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 integral type light transmission measurement device.
and diffuse transmittance (Td), Td/Tt×100
The haze value was determined. The various top paints used in the adhesive evaluation were prepared in the following manner. [Preparation of paint for evaluation] (1) Magnetic paint Dissolve nitrocellulose RS1/2 [manufactured by Flake Tycel Co., Ltd. containing 25% isopropanol] in Lutzker thinner for paint to prepare a 40wt% solution. 43.9 parts, followed by polyester resin (Desmofene #1700 manufactured by Bayer)
325 parts, 260g of chromium dioxide magnetic powder, soybean oil fatty acid (Resion P, manufactured by Riken Vitamin Co., Ltd.) as a dispersant/wetting agent, cationic activator (Cation AB, manufactured by Nippon Oil & Fats Co., Ltd.), and squalene (shark liver oil). ) respectively 1 part, 0.5 part and 0.8 part
part into a ball mill. 282 parts of a mixed solution consisting of methyl ethyl ketone (hereinafter abbreviated as MEK)/cyclohexanone/toluene = 3/4/3 (weight ratio) is further mixed and sufficiently pulverized to prepare a mother liquor paint (45 wt%). 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.) and 6.25 parts of butyl acetate were added.
Finally, 42.75wt% magnetic paint for evaluation was obtained. (2) Gravure printing ink Commercially available gravure ink for cellophane printing whose main binders are nitrocellulose and rosin oil: CLS-709 (Dainippon Ink Co., Ltd.)
2 parts of the stock solution was added to 1 part of a mixed solvent of toluene/ethyl acetate/methyl ethyl ketone = 1/1/1.
A paint for evaluation was prepared by diluting it in a proportion of 1.5 parts. (3) Gelatin paint 10 parts of photographic gelatin (Nitta Gelatin), 1 part of saponin, and 539 parts of distilled water were added to obtain a gelatin paint for simple evaluation with a solid content concentration of 2%. For (1) above, dry the three types of paints mentioned above on the biaxial polyester film that has completed the crystal orientation at 80°C for 1 minute, and then apply it to an average coating thickness of 5μ when using at 60°C for 24 hours. For (2), gravure coating was applied so that the coating thickness after drying for 1.4 minutes at 80℃ was 1.2μ on average, and for (3), the coating thickness was on average 0.6μ after drying at 110℃ for 2 minutes. The adhesion of these top coats was measured and the results shown in Table 1 were obtained.

[Table] Examples 1 to 8 (a) Preparation of aqueous polyester liquid Terephthalic acid (77 mol%) - 5Na-sulfoisophthalic acid (23 mol%) - 60 parts of ethylene glycol copolyester (molecular weight 6900) and nonionic interface Activator polyoxyethylene nonyl phenyl ether [HLB12.8 Nonion NS208.5
: manufactured by Nippon Oil & Fats Co., Ltd.] was heated and dissolved in 3000 parts of ion-exchanged water, and then cooled to prepare a coating solution. (b) Preparation of aqueous polyurethane liquid 203 parts of a commercially available polyester resin (Desmophen, a product of Bayer AG) consisting of hexanediol adipate and neopentyl glycol was stirred, dehydrated for 30 minutes at 20 mmHg, cooled, and then 203 parts of acetone was added. part was added to this and dissolved. 40.5 parts of 1.4-butanediol, toluylene diisocyanate (isomer ratio 2,4/
2,6=80/20) 69.7 parts, hexamethylene diisocyanate 33.6 parts, dibutyltin laurate
0.02 part was added, and 300 parts of acetone was added while stirring at 60°C. 19.3 parts of a 40 wt % aqueous solution containing equimolar addition of ethylene diamine to sodium acrylate was introduced and mixed therewith. Water after 32 minutes
709 parts were added dropwise, and the acetone was distilled off under reduced pressure.
A white dispersion (b-1) with a solid content of 47% was obtained. Next, 30 parts of hexamethylene diisocyanate was added to 100 parts of a triol with an OH value of 100, which was obtained by adding ethylene oxide to glycerin, and the mixture was reacted in an inert gas at 75°C for 3.5 hours.
- Add 20 parts of caprolactam and react at 75°C for 2 hours to form blocked polyisocyanate (b-
2) was obtained. Furthermore, polyethylene glycol (molecular weight
6000) 100 parts and toluylene diisocyanate 12
After reacting for 5 hours at 95°C in an inert gas, 13 parts of ε-caprolactam was added and the mixture was heated at 75°C.
The mixture was reacted for 2.5 hours to obtain blocked polyisocyanate (b-3). 80 parts of (b-2) and 60 parts of (b-3) were mixed and dropped into 200 parts of ion-exchanged water with stirring to obtain an aqueous dispersion (b-4) with a solid content of 40%. 196 parts of white dispersion (b-1), water dispersion (b
-4) 34.5 parts and the above surfactant nonionic
A coating solution was prepared by diluting 59.2 parts of NS208 with 2260 parts of ion-exchanged water. (c) Preparation of acrylic resin aqueous liquid Methyl methacrylate (50 mol%) - Ethyl acrylate (28 mol%) - Acrylic acid (2 mol%)
- Apply 300 parts of an aqueous dispersion of ammonium acrylate (20 mol%) copolymer with a solid content of 20% and 9.2 parts of the above surfactant (nonionic NS208.5) diluted with 3000 parts of ion-exchanged water. A liquid was prepared. (d) Production of easily adhesive film Polyethylene terephthalate, which has a polymer intrinsic viscosity of 0.65 as measured in O-chlorophenol at 25°C, was melt-extruded onto a rotating drum maintained at about 20°C to form an unstretched film of 158μ (microns). This was then uniaxially stretched 3.5 times in the machine direction. Next, the coating solution prepared in (a), (b), or (c) was applied to one side of the uniaxially stretched film by the kiss coating method, and then passed through a 98°C preheating zone.
This film was stretched 3.9 times in the transverse direction at 105°C. Further heat treatment was performed at 200° C. for 4.3 seconds to produce a biaxially stretched primer-coated film with an average coating weight of 100 mg/m ² and a thickness of 12.1 μm. The coated surfaces of these films were subjected to corona discharge treatment at a frequency of 110 KHz in air under atmospheric pressure. Table 2 shows the results of measuring the adhesion, surface smoothness, blocking resistance, and haze of the treated surface of the film thus obtained.

【table】

[Table] Comparative Example 1 The same procedure as in Example 8 was carried out except that the corona discharge treatment was not performed. The results are shown in Table 3. Comparative Example 2 The same procedure as Example 8 was carried out except that flame treatment was performed instead of corona discharge treatment. The results are shown in Table 3.

【table】

Claims (1)

[Scope of Claims] 1 Consists of a polyester film and a coating layer of water-based polyurethane, polyester resin, or acrylic resin coated on the surface of the film (however, it does not contain a swelling agent for the film), and the coating layer is Easily adhesive polyester film processed by electrical discharge treatment. 2 Easy adhesion characterized by applying an aqueous solution of aqueous polyurethane, polyester resin, or acrylic resin (however, it does not contain a swelling agent for the film) to the surface of a polyester film, drying it, and then subjecting it to electrical discharge treatment. Method for manufacturing polyester film.