JPH06293875A - Coating agent and easily adhesive polyester film coated therewith - Google Patents

Abstract

PURPOSE:To obtain a coating agent having excellent slip properties and blocking resistance to a polyester film and showing excellent adhesiveness to various coating materials, especially to a magnetic coating by compounding a water- insoluble copolyester and acrylic resin. CONSTITUTION:This coating agent is composed of a water insoluble resin dispersed in water, wherein each of discrete particles is consisting of a blended material of a copolyester with an acrylic resin. This invention further provides a polyester film coated with the coating agent dispersed in water and a manufacturing method of this film by an inline coating method.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coating agent for an aqueous dispersion formed from both a copolyester and an acrylic resin, and a coating agent prepared by applying the coating agent to at least one side of a polyester film and drying it. Involved in polyester film with coating film. The coating agent of the present invention has improved adhesion to the polyester film. Further, according to the present invention, a polyester film which is further excellent in water resistance and blocking resistance and is also highly slippery can be obtained, which is useful for packaging materials, magnetic cards, magnetic tapes, magnetic disks, printing materials and the like.

[0002]

BACKGROUND OF THE INVENTION Thermoplastic polyesters such as polyethylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), polyethylene naphthalene dicarboxylate or copolymers thereof, or blends thereof with small proportions of other resins. A polyester film obtained by melt-extruding a material or the like, biaxially stretching it, and then heat-setting it is excellent in mechanical strength, heat resistance, chemical resistance and the like, and is used in various industrial fields. However, since its surface is highly crystallographically oriented, there is a problem that it is poor in accepting paints, adhesives, inks and the like.

As a method of increasing the receptivity of the surface of the polyester film, there is a method of previously forming a primer layer (undercoat layer) of a synthetic resin on the surface of the film and forming a thin surface layer different from the base film. The primer layer is formed by applying a synthetic resin organic solvent solution or an aqueous solution onto the film surface.

As an aqueous resin solution for forming the primer layer, for example, in JP-A-60-248232, an aqueous solution of a polyester polymer having a substituent of a sulfonic acid derivative is disclosed in JP-B-55-3150. Aqueous liquids of acrylic polymers are used.

However, although the polyester polymer primer has excellent adhesiveness, it has a drawback that the film has poor slipperiness and wrinkles are formed when wound on a roll. On the other hand, an acrylic polymer primer has good slipperiness, but has a problem in adhesiveness.

[0006] Therefore, as a method for solving the drawbacks of both of these, a blend of a copolyester and an acrylic emulsion is proposed in Japanese Patent Application Laid-Open No. 60-63161. However, due to the particle property of the emulsion, molecular mixing of both polymers is unlikely to occur, resulting in a sea-island structure that cannot complement the defects of both polymers.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aqueous dispersion of a copolyester and an acrylic resin, which is excellent in water resistance and blocking resistance and can form an easily-adhesive coating film with excellent slipperiness. And to provide an easily-adhesive polyester film coated with the same.

[0008]

The present invention has the following constitution in order to achieve such an object.

1. An aqueous dispersion (copolyester / acrylic resin), characterized in that individual individual particles of the water-insoluble resin dispersion constitute a blend of copolyester resin and acrylic resin.

2. Copolyester / acrylic resin aqueous dispersion is applied to at least one side of the polyester film,
An easily-adhesive polyester film obtained by drying.

3. The copolyester / acrylic resin aqueous dispersion according to claim 1 is applied to at least one side of a polyester film before orientation crystallization is completed, then dried, stretched, and further heat-treated to complete orientation crystallization. This is a method for producing an easily-adhesive polyester film.

The present invention will be described.

The water-insoluble polyester component of this copolymer is a substantially linear polyester synthesized from a polybasic acid or its ester-forming derivative and a polyol or its ester-forming derivative.

The polybasic acid component of this polyester includes terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, p, p'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. , Phenylindane dicarboxylic acid, phenyl quinoxaline dicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, dimer acid and the like. Two or more of these components can be used. Further, a small proportion of an unsaturated polybasic acid such as maleic acid, fumaric acid or itaconic acid or a hydroxycarboxylic acid such as p-hydroxybenzoic acid or p- (β-hydroxyethoxy) benzoic acid may be used together with these components. it can. The ratio of the unsaturated polybasic acid component and the hydroxycarboxylic acid component is at most 10 mol%, preferably 5 mol% or less.

As the polyol component, ethylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylylene glycol, dimethylol. Propionic acid, glycerin, trimethylolpropane,
Examples thereof include poly (ethylene oxide) glycol, poly (tetramethylene oxide) glycol and the following bisphenol A derivatives. These can use 2 or more types.

[0016]

[Chemical 1]

The above polyesters are, for example, organic sulfonates, carboxylates, diethylene glycol,
Copolymers of hydrophilic group-containing compounds such as polyethylene glycol and polytetramethylene glycol are preferred because they are advantageous for preparing an aqueous dispersion. To introduce the carboxylic acid salt, a trifunctional or higher functional carboxylic acid is usually used. However, since this carboxylic acid causes branching in the polymerization step and is likely to gel, it is desirable to reduce the copolymerization ratio. In this respect, the introduction of a hydrophilic group using a sulfonate, diethylene glycol, polyalkylene ether glycol or the like is more advantageous because it does not cause a problem in the case of a carboxylate.

To introduce the sulfonate group into the polyester molecule, for example, 5-Nasulfoisophthalic acid, 5-ammoniumsulfoisophthalic acid, 4-Nasulfoisophthalic acid, 4-methylammoniumsulfoisophthalic acid, 2 -Na sulfoterephthalic acid, 5-K sulfoisophthalic acid, 4-K sulfoisophthalic acid, 2-K sulfoisophthalic acid, Na sulfosuccinic acid and the like sulfonic acid alkali metal salt-based compounds or sulfonic acid amine salt-based compounds can be used. preferable. The polyvalent carboxylic acid or polyhydric alcohol having a sulfonate group is 0.5 to 20 mol% in the total polyvalent carboxylic acid component or polyhydric alcohol component, and further 1
It is preferable to occupy -18 mol%.

In order to introduce a carboxylic acid group into the polyester molecule, for example, trimellitic anhydride, trimellitic acid, pyromellitic anhydride, pyromellitic acid,
Compounds such as trimesic acid, cyclobutane tetracarboxylic acid, and dimethylol propionic acid can be used.
The carboxylic acid salt can be obtained by neutralizing the carboxylic acid with an amino compound, ammonia, an alkali metal or the like.

When introducing the hydrophilic group-containing compound into the polyester molecule, various known methods can be adopted. The case of introducing a carboxylate or organic sulfonate group will be further described. For example, a method for synthesizing a polyester using a compound having a carboxylate or organic sulfonate group in the molecule as a starting material, After synthesizing a polyester using a compound having three or more carboxylic acid groups therein as one component of a starting material, the free carboxyl group in the polyester is converted to ammonia,
There are methods such as a method of neutralizing the medium with an amine or an alkali metal compound. The method will be further described. For example, trimellitic anhydride was used as one component of the polyester raw material to prepare a polymer having a free carboxyl group in the side chain, and after the reaction was completed, ammonia water was added to neutralize the aqueous polyester. Can be built. The polyester is preferably produced by a melt polymerization method.

The water-insoluble polyester in the present invention is
It can be produced by conventional polyester production techniques. For example, 2,6-naphthalenedicarboxylic acid or an ester-forming derivative thereof, isophthalic acid or an ester-forming derivative thereof, and 5-sodium sulfoisophthalic acid or an ester-forming derivative thereof are combined with ethylene glycol and an ethylene oxide adduct of bisphenol A. It can be produced by a method of reacting to form a monomer or an oligomer and then polycondensing under vacuum to obtain a polyester having a predetermined intrinsic viscosity. At this time, a catalyst that accelerates the reaction, such as an esterification or transesterification catalyst or a polycondensation catalyst, can be used, and various additives such as a stabilizer can also be added.

The intrinsic viscosity of the polyester component constituting the water-insoluble copolymer in the present invention is preferably 0.2 to 0.8. Here, the intrinsic viscosity is a value measured at 35 ° C. using o-chlorophenol.

Examples of the acrylic monomer constituting the water-insoluble acrylic resin include alkyl acrylate (wherein the alkyl group is methyl, ethyl, n-propyl, n-
Butyl, isobutyl, t-butyl, 2-ethylhexyl, cyclohexyl, etc.), alkyl methacrylate (the alkyl group is the same as above); 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate. Hydroxy-containing monomers such as acrylamide, methacrylamide, N-methylmethacrylamide, N-methylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N, N
-Dimethylol acrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide,
Amide group-containing monomers such as N-phenylacrylamide; N, N-diethylaminoethyl acrylate, N,
Amino group-containing monomers such as N-diethylaminoethyl methacrylate; epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; carboxyl groups such as acrylic acid, methacrylic acid and salts thereof (sodium salt, potassium salt, ammonium salt) or salts thereof And the like. These can be used in combination with other types of monomers. Examples of the other type monomer include epoxy group-containing monomers such as allyl glycidyl ether; sulfonic acid groups such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (sodium salt, potassium salt, ammonium salt, etc.) or monomers containing the salt. ;
Monomers containing carboxyl groups such as crotonic acid, itaconic acid, maleic acid, fumaric acid and salts thereof (sodium salt, potassium salt, ammonium salt, etc.) or salts thereof; acid anhydrides such as maleic anhydride and itaconic anhydride Group-containing monomers; vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester. , Vinyl chloride, vinyl acetate, vinyl chloride and the like. The water-insoluble acrylic resin is polymerized using one or more of the above monomers. The proportion of acrylic monomers in this polymer is preferably 50 wt% or more, more preferably 70 wt%.
% Or more.

The proportion of the copolymerized polyester and the acrylic resin in the individual particles of the water dispersion of the water-insoluble copolyester and the water-insoluble acrylic resin is 1: 9 to 9: by weight.
1, preferably 3: 7 to 7: 3, more preferably 4:
6 to 7: 3. The water-insolubility referred to here is 9
It refers to a state in which the resin dissolution rate in hot water at 5 ° C. is 10 wt% or less.

As a method for producing a blended water dispersion of the water-insoluble copolyester and the water-insoluble acrylic resin of the present invention, for example, both water-insoluble resins are completely dissolved in a low boiling point water-soluble solvent, and this solution is dropped into water. To obtain a dispersion. At this time, if a small amount of emulsifier is used, a stable dispersion having a small particle size can be obtained. This dispersion is desolvated if necessary. As the desolvation method, distillation under reduced pressure is preferable to distillation under normal pressure because scum generation during distillation is less and increase in particle size is less likely to occur.

As another desolvation method, a water-insoluble solvent is mixed with the above water dispersion and stirred, and the solvent in water is extracted and allowed to stand,
There is a method of taking out an aqueous dispersion after separating into two layers. This process is complicated and uses a large amount of solvent, which is a cost disadvantage. Vacuum distillation is the best desolvation method.

The water dispersion consisting of this water-insoluble (copolyester / acrylic resin) blend is applied to a polyester film.

Here, the polyester is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of such polyesters include polyethylene terephthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalene dicarboxylate, and the like. Blends with other resins in a small proportion are also included.

The linear saturated polyester in the present invention is
An agent that improves film properties, such as a lubricant, an antistatic agent, a colorant, a flame retardant, a light shielding agent, a stabilizer, and an ultraviolet absorber can be contained. The lubricant may be either internally precipitated particles or externally added particles, or may be a combination of two or more kinds. Examples of the externally added particles include silica, kaolin, calcium carbonate, calcium phosphate, titanium oxide, etc., and examples of the internally precipitated particles include a combination of an alkali (earth) metal compound, a phosphorus compound, etc., which are precipitated during polyester production. You can list things.

The polyester in the present invention is known per se and can be produced by a known method. Intrinsic viscosity of polyester (o-chlorophenol, 35
C) is preferably 0.45 to 0.9.

In the present invention, a polyester can be melt-extruded and rapidly solidified by a conventional method to obtain an amorphous unstretched film. And this unstretched film is
First, the film is stretched in the machine direction and then in the transverse direction. These stretchings are performed by running the film. As the stretching means in the machine direction and the transverse direction, known means can be used. For example, the longitudinal stretching (longitudinal stretching) is performed by heating the unstretched film with a heating roll group and utilizing the peripheral speed difference between the low speed roll and the high speed roll. At that time, it is preferable to provide an infrared heater between the low speed roll and the high speed roll to heat the film to the stretching temperature, or the low speed roll may heat the film to the stretching temperature. This stretching in the machine direction is usually 2.5-4.
Perform at 5 times magnification. The transverse stretching (transverse stretching) is performed using a tenter type stretching heat treatment device. This stretching in the transverse direction is usually performed at a magnification of 2.5 to 4.5 times. Then 15
Heat setting treatment is performed at a temperature of 0 to 240 ° C. to complete the oriented crystallization.

In addition to the sequential biaxial stretching method, the polyester film may be stretched by the simultaneous biaxial stretching method or multi-stage stretching method (length-width-length, length-width-length-width, length-length-width, length). -side-
(Horizontal etc.) can also be used.

The primer layer comprising the water-insoluble (copolyester / acrylic resin) blended water dispersion of the present invention comprises
It is preferably formed by applying a coating liquid in the process of manufacturing the polyester film. For example, it is preferable to apply the aqueous coating solution of the modified copolyester to the surface of the polyester film before the completion of the oriented crystallization process.

Here, the polyester film before the crystal orientation is completed is an unstretched film obtained by heat melting the polymer into a film as it is: the unstretched film is oriented in either the longitudinal direction or the transverse direction. Strained uniaxially stretched film: Furthermore, a film which is stretched and oriented at a low ratio in both longitudinal and transverse directions (a biaxially stretched film before it is finally restretched in the longitudinal or transverse direction to complete the oriented crystallization). ) Etc. are included.

The film of the present invention is preferably prepared by applying the coating solution of the above composition to a film which has not been stretched before crystal orientation is completed or has been stretched in at least a uniaxial direction, and is then longitudinally stretched and / or transversely stretched. It is manufactured by a so-called in-line coating method in which stretching and heat setting are performed. that time,
In order to allow the coating film to be smoothly applied to the surface of the polyester film before the process of oriented crystallization is completed, a corona discharge treatment is applied to the film surface as a pretreatment, or
Alternatively, it is preferable to use a chemically inert surfactant together with the coating composition. Such a surfactant accelerates the wetting of the polyester film so that the surface tension of the aqueous composition liquid can be lowered to 50 dyne / cm or less. For example, an anionic surfactant, a cationic surfactant, a nonionic surfactant. Surfactants such as activators are preferable, for example, polyethylene oxide / polypropylene oxide block copolymers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene-fatty acid esters, sorbitan fatty acid esters, glycerin fatty acid esters, fatty acid metal soaps, alkane sulfonic acids. salt,
Examples thereof include alkyl sulfates, alkylbenzene sulfonates, alkyl sulfonates, alkyl diphenyl ether disulfonates, alkyl sulfosuccinates, quaternary ammonium chloride salts, and alkyl amine hydrochloric acid. Among these, anionic or nonionic surfactants are more preferable in terms of liquid stability. The amount of the wetting agent is preferably 2 to 30% by weight, and more preferably 3 to 20% by weight based on the total solid content of the primer.

Further, within a range that does not eliminate the effects of the present invention, for example, an antistatic agent, an ultraviolet absorber, a pigment, an organic filler, an inorganic filler, a lubricant, an antiblocking agent,
Other additives such as crosslinking agents such as melamine, epoxy, aziridine can be mixed.

The solid content concentration of the aqueous primer coating liquid is usually 30% by weight or less, more preferably 10% by weight or less. The coating amount is 0.5 to 1 m ² of the running film.
20 g, more preferably 1-10 g.

As a coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a reverse coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method or the like may be applied alone or in combination. The aqueous primer coating liquid may contain a small amount of an organic solvent for the purpose of assisting the stability of the coating liquid or the coatability of the coating liquid.

This primer solution is applied to a polyester film immediately after being longitudinally and uniaxially stretched, and the film is then preheated and introduced into a tenter for lateral stretching and heat setting.

At this time, the applied aqueous liquid is dried in the preheating zone to the extent that some water remains. Then, the uniaxial film coated with the primer layer is transversely stretched by heating and then heat set by a high temperature treatment.

Conditions for oriented crystallization of polyester film,
For example, the conditions such as stretching and heat setting can be performed under the conditions conventionally accumulated in the art. For example, 80 to 140
The film is stretched at a temperature of ℃ and heat set at 180 to 240 ℃ for 1 to 10 seconds.

The polyester film having the primer layer thus obtained is used in various coating materials such as cellophane inks, magnetic paints, electrophotographic toner compositions, chemical mat paints, diazo paints and UV inks. It exhibits high adhesiveness to, especially strong adhesion to magnetic paint, and good blocking resistance without tackiness.

[0043]

EXAMPLES The present invention will be further described below with reference to examples.

In the examples, "part" means "part by weight". Each property of the film is measured by the following method.

1. Adhesiveness The evaluation coating material is applied to the primer-coated polyester film with a Meyer bar so that the thickness after drying is about 4 μm, and dried at 100 ° C. for 3 minutes. After that, aging was performed at 60 ° C. for 24 hours, and then Scotch tape No. 600
Adhesion (made by 3M) having a width of 12.7 mm and a length of 15 cm so that air bubbles do not enter.
975) described in the manual load roll to bring it into close contact,
Cut into tape width. The strength when peeled at 180 degrees is measured.

[Evaluation paint] Urethane resin Nipporan 2304 25 parts (manufactured by Nippon Polyurethane) PVC / Vinyl acetate resin S-REC A 50 parts (manufactured by Sekisui Chemical Co.) Dispersant Resion P (manufactured by Riken Vitamin) 1 part Magnetic Agent CTX-860 (manufactured by Toda Kagaku Co., Ltd.) (500 parts) is dissolved in a mixed solvent of methyl ethyl ketone / toluene / cyclohexanone to prepare a 40% solution, which is dispersed by a sand grinder for 2 hours. Thereafter, 25 parts (corresponding to solid content) of Coronate L as a cross-linking agent is added and well stirred to obtain a magnetic coating material.

2. Blocking property 10 after putting the front and back of the polyester film together
Cut into cm × 15 cm square, and apply a load of 50 kg / cm ² for 17 hours at 50 ° C. in an atmosphere of 50% RH,
Then, the peel strength of this 10 cm width is measured. The peeling speed at this time is 100 mm / min.

[0048]

Examples 1-5 and Comparative Examples 1-2 Polyethylene terephthalate having an intrinsic viscosity of 0.65 measured in 35 ° C. o-chlorophenol was melt extruded to obtain an unstretched film having a thickness of 158 μm, which was then machined. After being stretched 3.5 times in the direction, an aqueous primer coating solution (solid content: 4 wt%) having the composition shown in Table 1 was applied to one side of the uniaxially stretched film.
Then, it was stretched in the transverse direction at 105 ° C. by a factor of 3.9 to obtain 200
Heat treatment at 4.2 ℃ for 4.2 seconds, average coating amount 20mg / m
^A biaxially stretched primer-coated polyester film having a thickness of ² and a thickness of 12.2 μm was obtained. The adhesiveness and blocking resistance of the treated surface of this film were measured. The results are shown in Table 2.

[0049]

[Table 1]

Aqueous dispersions for the aqueous primer solutions of this Example and Comparative Example were prepared by the following method.

The water-insoluble polyester and / or acrylic resin shown in Table 1 was dissolved in tetrahydrofuran (THF),
A liquid having a resin content of 5 wt% was obtained. 100 parts of this THF solution was added dropwise to a solution of 45 parts of water and 50 parts of isopropanol, and then vacuum distillation was carried out at 4 ° C. for solvent removal to obtain an aqueous dispersion having a solid content of 9 wt%.

[0052]

Comparative Example 3 A plain biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the primer liquid was not applied. The characteristics of this film are shown in Table 2.

However, the symbols in Table 1 are as follows. TA; terephthalic acid IA; isophthalic acid QA; 2,6-naphthalenedicarboxylic acid K ₂ ; 5-sodium sulfoisophthalic acid EG; ethylene glycol BPA-4; bisphenol-A ethylene oxide adduct (4 mol) DEG; diethylene glycol MMA Methyl methacrylate EA; ethyl acrylate HEMA; 2-hydroxyethyl methacrylate N-MAA; N-methylol acrylamide GMA; glycidyl methacrylate

[0054]

[Table 2]

The slipperiness in Table 2 is measured by the following method.

According to ASTM D1894-63, the static friction coefficient (μs) between the primer-coated surface and the polyester film (non-coated surface) was measured using a slippery measuring device manufactured by Toyo Tester. The thread plate is a glass plate, and the load is 1 kg.

As is clear from Table 2, the easily-adhesive polyester films of the examples are excellent in adhesiveness, blocking property and slipperiness.

[0058]

INDUSTRIAL APPLICABILITY According to the present invention, various coatings applied to a polyester film, for example, offset ink,
Gravure inks, silk screen inks, UV inks, magnetic paints, adhesives, electrophotographic toners, chemical matte paints, diazo paints, hard coat paints, UV paints, heat sealability imparting compositions, inorganic film forming substances, etc., especially magnetic. It is possible to provide an easily-adhesive polyester film having a primer layer having excellent adhesiveness to a coating material, having no tackiness, and having good slipperiness, and a method for producing the same.

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Claims (3)

[Claims] 1. A coating agent in which a water-insoluble copolyester and a water-insoluble acrylic resin independently constitute a dispersed state as individual particles, and both resins are uniformly dispersed in water. 2. An easily-adhesive polyester film obtained by applying a water-insoluble (copolyester / acrylic resin) water dispersion on at least one surface of a polyester film and drying it. 3. A water-insoluble (copolyester / acrylic resin) aqueous dispersion is applied to at least one side of a polyester film before orientation crystallization is completed, dried, and then stretched and further heat-treated. , A method for producing an easily-adhesive polyester film capable of completing oriented crystallization.