JPS60248231A - Preparation of aqueous dispersion of polyester and easily bondable polyester film coated therewith - Google Patents

Abstract

PURPOSE:To obtain aq. dispersion of fine polymer particles having improved dispersion stability by dispersing uniformly a substantially water-insoluble polyester copolymer having 0.2-0.8 intrinsic viscosity and a specified compsn. in water contg. no org. solvent. CONSTITUTION:A copolymerized polyester having 0.2-0.8 intrinsic viscosity and being substantially insoluble in water is synthesized from an acid component consisting essentially of >=40mol% terephthalic acid and 0.5-5mol% arom. dicarboxylic acid contg. metallic salt residue of sulfonic acid, and a glycol component consisting essentially of ethylene glycol and 15-60mol% neopentyl glycol. The copolymerized polyester is dispersed uniformly in water contg. no org. solvent to obtain an aq. dispersion of polyester.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an aqueous polyester dispersion that imparts easy adhesion to a polyester film, and a method for producing an easily adhesive polyester film by applying the dispersion.

PRIOR ART Thermoplastic polyester, such as polyethylene terephthalate or its copolymer, polyethylene naphthalate or its copolymer, or a 7° blend of these and a small proportion of other resins, is melt-extruded to form a film. is publicly known. It is also known that the resulting biaxially oriented heat-set polyester film is superior in heat resistance, gas barrier properties + 1-temperature properties, and 1-type quality compared to 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 a synthetic resin layer is provided on the surface of such a polyvarnish film, the surface of the film is subjected to corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, or flame treatment to strengthen the adhesion between the two. A method of applying multiple synthetic resin coatings after activation has been applied. However, although these methods of activating the film surface can be expected to improve adhesion to the covering substance layer by increasing the secondary bonding force due to tying, the activity decreases over time. Therefore, these means for activating the film surface are not always satisfactory.

As another method for increasing the receptivity of the polyester film surface, a) etching method, in which the surface is swollen or partially dissolved with various chemicals, has been proposed. This process involves etching the film surface by contacting it with chemicals such as acid, alkali, amine aqueous solution, trichloroacetic acid, or phenols, thereby decomposing, dissolving, and relaxing the crystal orientation near the surface. This is intended to increase the adhesion with the binder resin without reducing the adhesiveness of the film, and its effect is most certain. However, some of the chemicals used in this method are harmful and can be dangerous to handle, and volatile substances from the chemicals are released into the atmosphere, so it is important to take all possible precautions to avoid contaminating the working environment. There are various disadvantages from a practical point of view, such as the need to be careful.

As a means similar to this method, a single layer of primer (undercoat layer) is previously provided on the surface of the film, 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. When forming the undercoat layer, the coating process is generally performed in a process different from the polyester film forming process 5-, so there is a risk that dust and dust from interfering objects IL may be mixed in during the process. Advanced processed film products, such as magnetic tape for auto tires.

Magnetic tape for wood, magnetic tape for computers, X
In applications such as H photographic film, printing photographic film, and diazo microfilm that must maintain precision and delicate quality, even if an easily adhesive surface is successfully formed, the resulting film may have surface defects due to dust. If so, it cannot be used as a base film for these purposes. In addition, when finishing the base film into the desired processed product, it is necessary to modify the surface once in the process to improve processability (
, Providing a separate process for Bra Immercoat treatment is
It lacks rationality and is almost impossible to achieve economically or industrially.

On the other hand, if the process of applying a primer (undercoat) is carried out in an atmosphere that is as dust-free as possible, i.e., during the polyester film manufacturing process, it can be used not only for the above-mentioned abrasive film but also for commercial purposes. becomes.

Therefore, ink and
It is desirable to perform in-subtraction processing. In the prior art, the method of modifying the surface of a polyester film to an easily adhesive surface by treating the surface with a primer is to apply a composition dissolved in an organic solvent to the surface Ii! of the film. If such a method is carried out during film production, it may contaminate the surrounding environment due to fugitive organic solvents, lead to undesirable safety and hygiene conditions, and adversely affect the film-forming process. It is best to keep the use of solvents to a minimum.Therefore, when performing in-line subbing treatment in the film forming process, it is recommended to use a composition that uses water as a solvent from the viewpoints of process, economy, and safety. 4. Preferred.

Many primer compositions using water as a solvent have been known, and many proposals have been made especially for aqueous solutions or dispersions of polyester copolymers. It is necessary to introduce a large amount of hydrophilic groups into the holomer, and the resulting primer film has poor water resistance.Also, if the amount of hydrophilic groups is suppressed for the purpose of improving water resistance, the dispersibility of poly7- In addition, it requires the addition of a small amount of organic solvent for dispersion, which is undesirable from the viewpoint of environmental pollution. For example, Japanese Patent Publication No. 47-40873 states that in order to dissipate polyester in water, It is stated that it is necessary to use a sulboa/acid metal base-containing compound with a molar ratio of 8 or more and polyethylene glycol with a molar ratio of 20 or more relative to the total glycol component.
-5476, the ester-forming alkali metal sulfonate as a polyester copolymerization component is 3.5 to 7.
It has been proposed to combine the use of 5 mol of diethylene glycol with the use of 30 to 100 mol of diethylene glycol as a glycol component; 0.5 to 10 mole of aromatic dicarboxylic acid and 2 to 6 of a water-bathable organic compound with a boiling point of 60 to 200°C as a dispersion.
A combination of 1' and 11 using water containing 6% has been proposed.

The above item (■) has extremely poor water resistance;
When the ester-forming alkali metal sulfonate is small, a large amount of diethylene glycol is required, and although the water resistance is improved, it is not sufficient. In addition, although the water resistance is considerably improved in the above method (2), an organic solvent is required and it is not suitable for in-line processing.

Purpose of the Invention The present inventor has arrived at the present invention as a result of extensive research into a primer composition that improves water resistance, which is a drawback of conventional polyester water dispersions, and provides excellent adhesion to base films. did.

9- Therefore, an object of the present invention is to provide an aqueous polyester dispersion that has excellent properties as a primer coating agent that improves the adhesion between various objects and a polyester film. Other objects of the invention are various coatings applied to polyester films, such as cellophane inks, magnetic paints, gelatin compositions, oatset inks, electrophotographic toners.

A polyester that has excellent adhesion to chemical matte paints, diazo paints, heat-sealable compositions, inorganic film-forming substances, etc., and can form a film with good moist heat blocking properties by Innoline subbing treatment. An object of the present invention is to provide an aqueous dispersion. Still another object of the present invention is to provide a method for producing polyester novelum which can be easily bonded by in-line subbing treatment. Still another object of the present invention is to provide a method for producing an easily adhesive polyester film, in which a film having excellent adhesion to various coatings and good moist heat blocking properties is formed by in-line subbing treatment. It's about doing.

1. A polyester obtained by uniformly dispersing a substantially water-insoluble polyester having an intrinsic viscosity of 0.2 to 0.8 in water, which is not limited to the solvent of the present invention. an aqueous dispersion, wherein the polyester comprises an acid component consisting primarily of terephthalic acid and an aromatic dicarboxylic acid containing an aromatic dicarboxylic acid having a sulfonic acid metal group, and wherein the terephthalic acid contains at least 40 moles. The aromatic dicarboxylic acid having the sulfonic acid metal group has a mole ratio of 0.5 to 5, and the glycol component constituting the polymer is mainly composed of ethylene glycol and neobentyl glycol, and the amount of neopentyl glycol is 5 to 5. A polyester aqueous dispersion characterized by being a copolymerized polyester having a molar ratio of 60,
and 2. Applying a polyester aqueous dispersion that imparts easy adhesion to the film on at least one surface of the polyester film before oriented crystallization is completed, and then drying, stretching and heat treatment to achieve oriented crystallization. In the method for producing an easily adhesive polyester film to be completed, the polyester aqueous dispersion is a polyester in which a substantially water-insoluble polyester having an intrinsic viscosity of 0.2 to 0.8 is uniformly dispersed in water containing no organic solvent. The polyester is an aqueous dispersion in which the acid component constituting the polymer is mainly composed of terephthalic acid and an aromatic dicarboxylic acid having a sulfonic acid metal base, and the terephthalic acid is present in a small amount (at least 40% The aromatic dicarboxylic acid having the sulfonic acid metal group has a mole ratio of 0.5 to 5, and the glycol component constituting the polymer is mainly composed of ethylene glycol and neobenzeneyl glycol, and the neobenthyl glycol has a mole ratio of 0.5 to 5. This is achieved by a method for producing an easily adhesive polyester film characterized by a copolymerized polyester having a molecular weight of 60 to 60.

In the present invention, the copolyester to be dispersed in water is
The acid component constituting the polymer is mainly composed of aromatic dicarboxylic acids containing aromatic dicarboxylic acids having terephthalate and sulfonic acid metal bases. The terephthalic acid must account for at least 40 moles of the total acid component, and the aromatic dicarboxylic acid having a sulfonic acid metal base must account for 0.5 to 5 moles of the total acid component. If the proportion of terephthalic acid is less than 40 mole, or if the proportion of aromatic dicarboxylic acid having a sulfonic acid metal base exceeds 5 mole, the blocking resistance of the film is undesirably lowered. Further, if the proportion of the aromatic dicarboxylic acid having a sulfonic acid metal group is less than 0.5 molar ratio, it is not preferable because it becomes difficult to water-disperse the copolyester.

13- The above-mentioned aromatic dicarboxylic acid having a sulfonic acid metal base is a compound having a sulfonic acid metal base (
-8o3M: A compound in which M is a monovalent metal) is bonded. Among these valent metals, alkali metals, especially sodium and potassium, are preferred. An example of the aromatic dicarboxylic acid having a sulfonic acid metal group is 3-sulfophthalic acid.

Examples include alkali metal salts (eg, sodium salts, potassium salts, etc.) of 4-sulfophthalic acid, 4-sulfoisophthalic acid, 5-sulfoisophthalic acid, and sulfoterephthalic acid. Among these, sodium sulfoterephthalic acid, potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, and 5-potassium sulfoisophthalic acid are preferred. stomach. Such a compound has a great influence on the water dispersibility of the copolyester and the moisture resistance of the film, and the preferred proportion thereof is 0.5 to 4 moles.

14- The acid component of the copolymerized polyester contains an aromatic dicarboxylic acid having terephthalic acid and a sulfonic acid metal base in the proportions mentioned above, but other aromatic dicarboxylic acids that can be used together with these include, for example, isophthalic acid. Examples include phthalic acid, naphthalene dicarponoic acid, diphenyl dicarboxylic acid, and the like. Among these, isophthalic acid is particularly preferred. Further, other aromatic dicarboxylic acids may be substituted with aliphatic dicarboxylic acids and/or alicyclic dicarboxylic acids as long as they account for less than 10 molar proportions of the total acid components. Examples of aliphatic dicarboxylic acids include adipic acid, azelaic acid, and sebacic acid, and examples of alicyclic dicarboxylic acids include 1,3-cyclohexanedicarboxylic acid.

Examples include 1,4-cyclohexanedicarboxylic acid.

Further, the glycol component constituting the copolymerized polyester is mainly composed of ethylene glycol and neopentyl glycol, and the neopentyl glycol contains 5 to 60%
There must be a staff member. The preferred proportion of neopentyl glycol used is 10 to 50 moles.

If the proportion of neopentyl glycol is less than 5 molar ratio, the water dispersibility of the copolymerized polyester will be insufficient (and if it exceeds 60 molar ratio, the water dispersibility of the copolymerized polyester will improve, but the moisture blocking property and heat blocking property of the film will be reduced). Ethylene glycol is not preferable because it has poor properties.If the proportion of ethylene glycol is less than 10 molar percentage of the total glycol components, it is an aliphatic glycol other than ethylene glycol and neopentyl glycol, such as tbal, 2-propanediol.

It may be substituted with 1.3-propanediol, 1.5-bentanediol, 1,6-hexanediol, etc.

The copolymerized polyester in the present invention is composed of the above-mentioned components, and must have an intrinsic viscosity of 0.2 to 0.8. Here, the intrinsic viscosity is a value measured at 25°C using 0-chlorophenol. If the intrinsic viscosity of the copolymerized polyester is less than 0.2, adhesiveness will decrease;
Exceeding this is not preferable because the water dispersibility decreases. Further, the copolyester must be substantially insoluble in water, and the term "substantially insoluble in water" as used herein means that the copolyester is made into angular chips of 3 to 5 nXs, and the chips are When added to hot water at 90°C and heated for 3 hours, the elution bond reduction is 1% or less, preferably 0.
It means less than 5 parts by weight, sometimes preferably less than 0.1 parts by weight.

The copolymerized polyester in the present invention can be manufactured using conventional polyester manufacturing techniques. For example, terephthalic acid or its ester-forming derivatives are reacted with ethylene glycol and neopentyl glycol to form a heptamer or oligomer, to which an aromatic dicarboxylic acid having a sulfonic acid metal group is added. It can be produced by a method in which a polymer having a predetermined intrinsic viscosity is obtained by polycondensing the polymer and then polycondensing it. In this case, catalysts that promote the reaction, such as esterification or transesterification catalysts, polycondensation catalysts, etc., may be used, and various additives such as modifiers, stabilizers, etc. may also be added. As the catalyst, a catalyst used in the production of borie 1,000 terephthalate is preferably used.

The aqueous polyester dispersion of the present invention is obtained by uniformly dispersing the copolymerized polyester in water. This aqueous dispersion can be produced by the following method.

The copolyester is first dissolved in a hydrophilic organic solvent having a solubility in water of 1) of 20.9 or more at 20°C and a boiling point of 100°C or lower, or an azeotrope with water at 100°C or lower. Examples of this organic solvent include acetone, tetrahydrofuran, ethyl acetate, and methyl ethyl ketone.

18- is then added to the organic solution in which the copolymerized polyester is dissolved, with stirring, preferably while heating and stirring at high speed, to form a bluish-white to milky-white dispersion. Alternatively, a bluish-white to milky-white dispersion can be obtained by dropping the organic solution into water under stirring. The obtained dispersion is further distilled under normal pressure, preferably reduced pressure to remove the hydrophilic organic solvent, to obtain the desired polyester aqueous dispersion. When copolymerized polyester is dissolved in a hydrophilic organic solvent that is azeotropic with water, the water will be azeotropic when the organic solvent is distilled off. It is desirable to have them dispersed. The solid content concentration after distillation is desirably 40% by weight or less; if it exceeds 40% by weight, the copolyester fine particles dispersed in water are likely to reagglomerate, resulting in a decrease in the stability of the aqueous dispersion. The solid content concentration of the aqueous dispersion is preferably 20% by weight or less. On the other hand, there is no particular lower limit to the solid content concentration, but it is preferably 0.1 weight factor or more.

The aqueous polyester dispersion thus obtained can be applied to one or both sides of a polyester film, which will be described later, and dried to impart easy adhesion to the film.

In the present invention, the polyester forming the polyester film is a high-melting, crystalline, linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Examples of such polyesters include polyethine terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, 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 the above-mentioned linear saturated polyester, forming it into a film by a conventional method, and subjecting it to oriented crystallization and heat treatment crystallization. This polyester film has a heat of crystal fusion measured by a scanning calorimeter in a nitrogen stream [at a heating rate of 10°C/min], which is usually 4aIt/
The crystals are oriented to the extent that it exhibits a particle diameter of 100 g or more.

In the present invention, a polyester fill film before oriented crystallization is an unstretched film obtained by thermally melting polyester and forming it into a film as it is; an unstretched film that is stretched in either the vertical direction or the horizontal direction. An oriented uniaxially stretched film; a biaxially stretched film that is further stretched 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:

When applying the polyester aqueous dispersion, a necessary amount of surfactant such as anionic surfactant or nonionic surfactant is added.1. It can be used as As an effective surfactant, the surface tension of polyester aqueous dispersion is 40 dyn.
The surfactant can be reduced to less than e/α and promotes wetting to the Shikushiben polyester film, and many known surfactants can be used. Examples include polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap.

Examples include alkyl sulfates, alkyl sulfonates, alkyl sulfosuccinates, quaternary ammonium chlorides, alkylamine hydrochlorides, and dodecylbenzenesulfonic acid sodium salts. The coating may be applied to a thickness that completely covers the surface layer of the polyester film.

When forming a single layer of primer, it is necessary to apply the polyester film before crystal orientation is complete.

At this time, on the surface of the polyester film before stretching and orientation,
Any known coating method can be used to apply the polyester aqueous dispersion. For example, roll coating method,
A gravure coating method, a roll plush method, a spray coating method, a towware knife coating method, an impregnation method, a curtain coating method, etc. may be applied alone or in combination.

In the coating step, the surface layer of an unstretched film cast by melt extrusion of polyester, or the surface layer of a film immediately after being stretched in either the vertical or horizontal direction is preferably targeted. In order to form a single layer of primer and at least exhibit its effectiveness, the coating film should be dried just before heat setting, and then the coating film on the ring should be heated for 2 seconds at a temperature of at least 120°C. It is preferable to apply the primer layer by first collecting an unstretched film or a -axially stretched film, coating and drying it outside the film production line, and then biaxially or -axially stretching and heat setting. Although Bamboo 5 can also be used, it is preferable to apply it in the film production line from the viewpoint of primer treatment effect and economy.

The highly adhesive polyester film of the present invention is suitable for cellophane ink and adhesive paint.

Extremely wide-ranging adhesion to gelatin compositions, 7-pole oil-based offset ink rim photographic toner compositions, chemical matte paints, diazo paints, heat-sealable silk compositions, inorganic coating-forming substances, and metal vapor deposition substances. Indicates adhesion performance.

Example Hereinafter, a detailed explanation will be given 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. Adhesive Primer Covering Treatment: Coat a Nipolyester film with the top coat for each ridge under specified conditions, and apply Scotch Tape A 600 (manufactured by Three M Company) width 19.4 mm, length 8 cm.
Adhere the In without creating any air bubbles, and apply JIS on top of this.
C2701 (1,975) using a manual load roll to flatten the laminated portion for 5 cm using a Tensilon UM-II manufactured by Toyo Boldwy Co., Ltd. at a head speed of 30011.
The sample was peeled off in a T-shape at a speed of 11/min, the peel strength at this time was measured, and this was divided by the tape width to obtain υi. Furthermore, T
The laminate was taken with the tape side down and the gap between the chucks was 5 crn.

2. Surface slipperiness The coefficient of static friction was measured on the primer-coated surface and the non-coated surface at a temperature of 20° C., a humidity of 60 qbRH, using a sliver measuring tester manufactured by Toyo Tester Co., Ltd.

3. Blocking resistance Two films (50 mm x 50 m) were placed on top of each other on the treated surfaces, and a pressure of 2 kg/C1d was applied to them at 60°C x s.
After 24 hours in an RH atmosphere, it was peeled off and its condition was rated on a five-point scale.

5: All (peel off without noise or resistance) 4: Peel off with a slight sound 3: Peel off with a sound and some resistance - 25 = 2: Peel off with a loud noise and high resistance 1 : Adhesive and cannot be peeled off [Preparation of paint for evaluation] (1) Dissolve nitrocellulose R8I/2 (manufactured by Flake Tycel ■ containing 25% isopropanol) in lacquer thinner for magnetic paint paints, and add 40 wt'l solution. was prepared, 43.9 parts of this solution was added, and then polyester resin (
32.5 parts of Desmofene-4P1700 (manufactured by Baikuru Co., Ltd.), 2.60 parts of chromium dioxide magnetic powder, 1 soybean oil fatty acid (Legion P: manufactured by Riken Vitamin ■) as a dispersant/wetting agent,
A cationic activator (manufactured by Rikisenon AB NOF ■) and squalene (shark liver oil) were used at 1 part, 0.5 part, and 0.0 parts, respectively.
Put 8 parts into a ball mill. Methyl ethyl ketone (hereinafter abbreviated as MgK) / hexane / toluene =
282 parts of a mixed solution consisting of 3/4/3 (weight ratio) is further mixed and sufficiently pulverized to prepare a mother liquor paint (45wt4). To 50 parts of this mother liquor, an addition reaction product of trimethylolpropane and tolulein diisocyanate 48S (coronate) was added to Ichi Nippon Polyurethane Industry Co., Ltd. and 6.2 parts of dithyl acetate.
A 5 wt % magnetic paint for evaluation was obtained.

(2) Gravure printing ink Commercially available gravure ink for cellophane printing mainly using nitrocellulose and rosin oil: CLS-709 white (manufactured by Inu Nippon Ink ■) original fi
, 2 parts were diluted with 1 part of a mixed solvent of tononicin/ethyl acetate/methyl ethyl ketone = 1/1/1 to prepare a paint for evaluation.

(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.

Example 1 a) Preparation of polyester aqueous dispersion 95 parts of dimethyl terephthalate, 95 parts of inphthalic acid, 5
- 6 parts of dimethyl seongum sulfoisophthalate, 90 parts of ethylene glycol.

92 parts of neopentyl glycol, 0.1 part of zinc acetate, and 0.1 part of anti-chloride trioxide were added to the reactor, and heated to 170 to 200°C under a nitrogen stream to distill off the methanol produced. A transesterification reaction was performed. From the latter half of the reaction, the temperature of the reaction system was gradually raised to 1c250°C. When methanol distillation is completed, phosphorous acid is 0.
．． 04 parts was added, and then the pressure inside the system was reduced to 20wH9 to carry out a polycondensation reaction, resulting in a copolymerization polymer with an intrinsic viscosity of 0.4.
An ester was obtained.

The composition of the copolyester is shown in Table 1.

Add 20 parts of this copolyester to 8 parts of tetrahedron
180 parts of water was added dropwise to the resulting solution under high speed stirring at 10,000 revolutions/min to obtain a bluish milky dispersion. This dispersion was then added to 20 vnk19
The mixture was distilled under reduced pressure to remove tetrahydrofuran. In this way, a polyester aqueous dispersion with a solid content concentration of 10 wt4 was obtained.

Furthermore, 2 parts of an anionic surfactant: polyoxyethylene nonylphenyl ether (HLB=12.8) was added to 180 parts of the polyester aqueous dispersion, and 61 B parts of additional water was added to prepare a coating liquid.

b) Production of easily adhesive polyester film 25°C 0-
When polyethylene terephthalate (containing lubricant) with an intrinsic viscosity of 0.65 measured in chlorophenol was maintained at approximately 20°C? Melt extruded onto a drum to 158μ (microns)
' was obtained, and this was then stretched in the machine axis direction to form 3.
After stretching 5 times, the coating solution prepared in a) above was applied to one side of the uniaxially stretched film by a kiss coating method. after that,
The film was passed through a 98° C. preheating screen and stretched 3.9 times in the transverse direction at 2,105° C. Subsequently, a heat treatment was performed at 200° C. for 4.2 seconds to obtain a biaxially stretched primer-coated polyester film having an average coating weight of 15 Da/bar and a thickness of 12.2 μm. Adhesion of the treated side of this film.

Surface smoothness and blocking resistance were measured.

The results are shown in Table 1.

Examples 2 to 4 and Comparative Examples 1 to 3 a) Preparation of polyester aqueous dispersion Dimethyl terephthalate, dimethyl isophthalate and 5-
A copolymerized polyester having the composition shown in Table 1 was obtained in the same manner as in Example 1 a) except that the proportion of dimethyl sodium sulfoisophthalate and the proportion of ethylene glycol and neopentyl glycol were changed. Further, except for using these copolymerized polyesters, the procedures in Example 1 a) and F[ were repeated to prepare a polyester aqueous dispersion and further a coating liquid.

130-b) Production of easily adhesive polyester film A biaxially stretched primer-coated polyester film was obtained in the same manner as in Example 1 b), except that the coating solution prepared in a) above was used. Adhesion 1 Surface smoothness and blocking resistance of the treated surface of this film were measured. The results are summarized in Table 1.

Comparative Example 4 A biaxially stretched polyester film was obtained in the same manner as in Example 1 b), except that the aqueous polyester dispersion was not applied, that is, no primer coating was performed, and the surface properties of the film were measured. The results are shown in Table 1.

Effects of the Invention The aqueous polyester dispersion of the present invention has excellent dispersion stability of polymer particles, and furthermore, a single layer of primer with excellent adhesiveness can be coated on the surface of the biaxially stretched polyester film during the production process of the film. At this time, since the medium is water, it does not pollute the working environment, and the heating zone for the stretching process can be shared, so it can be said to be very advantageous in terms of cost compared to other primer treatment methods.

Furthermore, the biaxially oriented polyester film coated with the aqueous polyester dispersion of the present invention exhibits excellent adhesion to various coatings, and also has the advantage that the coated surface (primer layer) does not stick under conditions of high temperature and high humidity. It has excellent blocking resistance.

=33- Continuation of page 1 ■Int, C1,' Identification symbol Office serial number ○ Invention
Person Tamaki Kanai Sagamihara City Elementary School

Claims (1)

[Claims] 1. A polyester aqueous dispersion in which a substantially water-insoluble polyester having an intrinsic viscosity g O of 2 to 0.8 is uniformly dispersed in water containing no organic solvent, the polyester but,
The acid component constituting the polymer is mainly composed of an aromatic dicarboxylic acid containing terephthalic acid and an aromatic dicarboxylic acid having a sulfonic acid metal group, and the terephthalic acid has at least 40 molar proportions, and the aromatic dicarboxylic acid having the sulfonic acid metal group It is a copolymerized polyester in which the dicarboxylic acid has a molar ratio of 0.5 to 5, and the glycol component constituting the polymer is mainly composed of ethylene glycol and neopentyl glycol, and the neopentyl glycol has a molar ratio of 5 to 60. % polyester water dispersion. 2. Before oriented crystallization occurs, a polyester aqueous dispersion that imparts easy adhesion to the film is applied to at least one side of the polyester film, and then dried, stretched, and heat treated to achieve oriented crystallization. In the completed method for producing an easily washable polyester film, the polyester aqueous dispersion uniformly disperses a substantially water-insoluble polyester having an intrinsic viscosity of 0.2 to 0.8 in water containing no organic solvent. An aqueous polyester dispersion, wherein the polyester is composed mainly of an aromatic dicarboxylic acid containing terephthalic acid and an aromatic dicarboxylic acid having a sulfonic acid metal base, and the acid component constituting the polymer is composed of terephthalic acid and an aromatic dicarboxylic acid containing an aromatic dicarboxylic acid having a sulfonic acid metal base, is at least 40 mol, and the aromatic dicarboxylic acid having the sulfonic acid metal group is 0.5 to 5 mol. A method for producing an easily adhesive polyester film, characterized in that the copolyester contains 5 to 60 moles of bentyl glycol.