JP3185367B2 - Easy adhesion polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field 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 which has excellent adhesiveness and blocking resistance and is suitable as a base film used for magnetic recording materials, various photographic materials, packaging materials, electric insulating materials, general industrial materials and the like. Particularly, the present invention relates to an easily adhesive polyester film suitable as a base film used for a magnetic recording material.

[0002]

2. Description of the Related Art Polyesters, especially polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate or poly-1,4-cyclohexane dimethylene terephthalate, and polyesters based on these, have excellent physical and chemical properties. They are widely used as fibers, films or sheets, and as molded products thereof. In particular, polyester films have excellent properties in heat resistance, chemical resistance, and mechanical properties, and are used in many applications such as magnetic recording materials, various photographic materials, packaging materials, electrical insulating materials, and general industrial materials. I have.

[0003] However, since the polyester itself is generally inert and has poor adhesion, various coatings such as a magnetic paint, a chemical mat paint, a diazo photosensitive paint, a gelatin composition, a heat seal composition,
When applying or printing ink, etc., in order to improve the adhesiveness with the coating, the film surface is subjected to physical treatment such as corona discharge or plasma, or chemical treatment using alkali or amine chemicals. There is known a method of performing an appropriate treatment, and a method of coating an easily adhesive substance. However, the physical or chemical surface treatment method complicates the process, not only increases the cost, but also does not provide sufficient adhesiveness.

On the other hand, a method of coating an easily adhesive substance can be carried out in the process of producing a polyester film, which is advantageous in terms of cost, and enables selection of an adhesive substance which can cope with various coatings. is there. Further, from the viewpoints of handleability of the polyester film and workability at the time of producing the film, various water-dispersed or water-soluble copolymerized polyesters and lamination or coating of the copolymerized polyester on a polyester film have been proposed. For example, Japanese Patent Publication No. 47-40873 and Japanese Patent Application Laid-Open No. 50-1
JP-A-21336 discloses copolymers of polyester with polyethylene glycol and an ester-forming sulfonic acid metal salt compound.
JP-A-4-3848, JP-A-56-144150, JP-A-57-70153, JP-A-57-70
177 and JP-A-59-215318 include those obtained by copolymerizing a metal salt compound of an ester-forming sulfonic acid and an aliphatic dicarboxylic acid component, and those obtained by laminating or coating a polyester film.

[0005]

However, the above-mentioned prior art has the following problems. That is, conventional water-dispersible or water-soluble copolymerized polyesters and those obtained by laminating or applying the copolymerized polyester to a polyester film are used for the purpose of improving the water-dispersed or water-soluble properties, with the ester-forming metal salt compound of sulfonic acid and polyethylene glycol or There is a combination of an aliphatic dicarboxylic acid component and the like, but water dispersion or water solubility is not sufficient, and further, in order to copolymerize two or more kinds of polyethylene glycol or an aliphatic dicarboxylic acid component,
The laminated or coated polyester film exhibits adhesiveness due to a remarkable decrease in the glass transition temperature of the polyester, but has drawbacks such as remarkably poor blocking resistance and reduced workability. In addition, polyester is liable to be charged with negative potential static electricity due to friction, peeling, etc., especially when laminated with sulfonic acid group-containing copolymerized polyester, the tendency is remarkable, and there are problems with explosion proof property, adhesion of foreign matter, applicability etc. Had occurred.

The present invention solves these drawbacks, is excellent in adhesiveness and blocking resistance, gives a positive charge to the polyester film, and makes the potential plus or minus by contact with a silicon rubber or a metal roll in a processing step. An object of the present invention is to provide a readily adhesive polyester film suitable as a base film used for a magnetic recording material or the like by eliminating a trouble of static electricity by approaching zero.

[0007]

According to the present invention, there is provided an easily adhesive polyester film according to the present invention, wherein at least one side of the polyester film comprises at least 50 mol% of an aromatic dicarboxylic acid component and 5 to 50 mol% of an ester-forming substance. A layer composed of a water-soluble copolymerized polyester composed of an acid component and a glycol component composed of an alkali metal salt of sulfonic acid and a layer composed of a silane coupling agent, that is, a coating liquid composed of these components was laminated as an easy-adhesion layer. Consist of things.

The polyester constituting the polyester film in the present invention is produced by esterification or transesterification of a dicarboxylic acid or an ester-forming derivative thereof with glycol and a polycondensation reaction. The type of polyester is not particularly limited as long as it can be formed into a film. Suitable polyesters that can be formed into films are those using aromatic dicarboxylic acids as dicarboxylic acid components, for example,
Polyethylene terephthalate, polyethylene-p-oxybenzoate, polyethylene-1,2-bis (2-chlorophenoxy) ethane-4,4, -dicarboxylate, polyethylene-1,2-bis (phenoxy) ethane-4,4, -Dicarboxylate, polybutylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexane dimethylene terephthalate, and the like. Among them, polyethylene terephthalate is most preferable in consideration of quality, economy, and the like. . Therefore, polyethylene terephthalate (hereinafter P
ET) will be described as a typical example of polyester. Of course, these polyesters may be homopolyesters or copolyesters, and the components to be copolymerized include various aromatic dicarboxylic acid components, aliphatic dicarboxylic acids, oxycarboxylic acids and various glycols. . Also, known additives to the polyester constituting the polyester film, for example,
Flame retardants, heat stabilizers, UV absorbers, organic lubricants such as pigments, dyes, fatty acid esters and waxes, or defoamers such as polysiloxanes, and clay, mica, titanium oxide, and carbonic acid for the purpose of imparting slipperiness Inorganic particles such as calcium, kaolin, wet and dry silica, colloidal silica, calcium phosphate, barium sulfate, and alumina, as well as organic particles containing acrylic, styrene, silicon, and the like as components may be blended.

The polyester film of the present invention comprises:
In the state where the easy-adhesion layer is laminated, biaxially oriented one is preferable from the viewpoint of mechanical and thermal characteristics. For example, the polyester is dried, melt-extruded to form an unstretched sheet, and then biaxially stretched and heat-treated to produce a film.
The biaxial stretching may be any of longitudinal and transverse sequential stretching or simultaneous biaxial stretching, and the stretching ratio is not particularly limited, but usually 2.0 to 5.0 times each in the longitudinal and transverse directions. Alternatively, after the stretching in the longitudinal and transverse directions, the film may be stretched again in the longitudinal or transverse direction. The thickness of the polyester is not particularly limited, but is preferably 2 to 500 μm.

In the present invention, it is necessary that at least 50 mol% of the water-soluble copolymerized polyester to be laminated on the polyester film surface is an aromatic dicarboxylic acid component. As the aromatic dicarboxylic acid component, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid,
Aromatic dicarboxylic acids such as diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, 1,2-bis (phenoxy) ethane P, P, -dicarboxylic acid, and ester-forming derivatives thereof can be mentioned. Of these, use of terephthalic acid or naphthalenedicarboxylic acid is preferred because of its excellent adhesion and blocking resistance. Further, it is preferable to use these aromatic dicarboxylic acid components alone. The aromatic dicarboxylic acid component needs to be 50 mol% or more, preferably 60 mol% or more, and more preferably 70 mol% or more.
Mol% or more. When the amount of the aromatic dicarboxylic acid component is less than 50 mol%, the adhesion is good, but the blocking resistance is undesirably reduced.

The ester-forming sulfonic acid metal salt compounds of the present invention include sulfoterephthalic acid, 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, and 4-sulfonaphthalene-2,6-dicarboxylic acid. And the like, and their ester-forming derivatives. Among them, 5-sulfoisophthalic acid and sodium and potassium salts of sulfoterephthalic acid are more preferably used.

The amount of the ester-forming sulfonic acid metal salt compound must be 5 to 50 mol%, preferably 8 to 45 mol%, more preferably 10 to 30 mol%, based on all dicarboxylic acid components. . If the amount of the ester-forming sulfonic acid metal salt compound is less than 5 mol% based on all dicarboxylic acid components, it is not preferable because sufficient water solubility and adhesiveness cannot be obtained. On the other hand, if it exceeds 50 mol%, the adhesiveness reaches saturation, and conversely, the blocking resistance decreases, which is not preferable.

In the present invention, the glycol components include ethylene glycol, 1,2-propanediol, 1,3
-Propanediol, neopentyl glycol, 1,3
-Butanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,2
-Cyclohexane dimethanol, 1,3-cyclohexane dimethanol, 1,4-cyclohexane dimethanol, bisphenol derivatives, and glycols such as polyalkylene glycol. Among them, ethylene glycol, bisphenol A or bisphenol S
Is preferred. The copolymerization amount of the ethylene oxide adduct of bisphenol A or bisphenol S in all the glycol components is not particularly limited, but is preferably 10 to 50 mol%.

In the present invention, it is necessary to add a silane coupling agent to the water-soluble copolymerized polyester. The silane coupling agent referred to in the present invention has, in the molecule, a group that reacts with organic substances such as an amino group, an epoxy group, a vinyl group, a methacryl group, and a mercapto group and a hydrolyzable alkoxy group such as a methoxy group and an ethoxy group. The compound is not particularly limited as long as it is a compound, but typical examples are γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, aminosilane, γ-methacryloxypropyl Trimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltriacetoxysilane,
γ-glycidoxypropylmethyldimethoxysilane, methyltrimethoxysilane and the like can be mentioned.

These silane coupling agents undergo a cross-linking reaction with a functional group, such as a carboxyl group or a hydroxyl group, present in the water-soluble copolyester, and more firmly bond the polyester substrate to the water-soluble copolyester easy-adhesion layer. In addition, it functions as a cross-linking agent that also bonds with a coating layer (for example, a magnetic layer) laminated on the easy-adhesion layer. Among them, γ-glycidoxypropyltrimethoxysilane (hereinafter sometimes abbreviated as GPS), γ- (2
-Aminoethyl) aminopropyltrimethoxysilane (hereinafter sometimes abbreviated as APS) and methyltrimethoxysilane (hereinafter sometimes abbreviated as MTS) are preferred. Among them, GPS having good charging characteristics is particularly preferable.
The addition amount of the silane coupling agent (hereinafter may be abbreviated as SCR) is not particularly limited, but the weight ratio of the solid content (A) / SCR (B) of the water-soluble copolymerized polyester is 99 /. 1-1 / 99, preferably 97 / 3-1
0/90, more preferably in the range of 95/5 to 50/50. When the amount of SCR added is 1% by weight or less based on the solid content of the water-soluble copolymerized polyester, the adhesion, the charging characteristics,
The effect of improving blocking resistance and the like is poor, and if it is 99% by weight or more, poor adhesion of the easily adhesive layer occurs, which is not preferable. Two or more of these SCRs may be used in combination. Also,
Various lubricants, various waxes, various surfactants, various antistatic agents, various antifoaming agents, and the like may be added to the above-mentioned easy-adhesive coating agent as long as the effects of the present invention are not impaired.

The mechanism by which the charging of the polyester film by the addition of GPS of the present invention is converted to a positive potential is not well understood at present, but among SCRs, an epoxy group-containing alkoxysilane is particularly good, so that the epoxy group has a positive potential. It is presumed that it plays a role of converting into.

The thickness of the water-soluble copolymerized polyester film applied on the polyester film substrate of the present invention is 0.01 to 1 μm, preferably 0.03 to 0.5 μm.
m, more preferably 0.05 to 0.3 μm.
When the thickness of the coating is less than 0.01 μm, the adhesiveness is poor. Conversely, when the coating is 1 μm or more, the coating itself is easily cleaved and the moisture resistance, blocking resistance, solvent resistance, etc. are deteriorated. Not preferred. The center line average roughness (R
a) is 0.001 to 0.1 μm, preferably 0.00
1 to 0.05 μm, more preferably 0.001 to 0.0
The range is 1 μm. When the center line average roughness (Ra) of the coating film is 1.0 μm or more, the surface is too rough, resulting in poor adhesion, and when used as a magnetic material, has poor magnetic properties. Is not preferred.

The thickness of the coating film can be measured by various methods. For example, the cross section of the laminated film is measured by an electron microscope, and when the coating film can be removed with a solvent or the like, the removed portion and the removed portion are removed. It can also be obtained from the step of the part that does not exist. The intrinsic viscosity of the water-soluble copolymerized polyester (measured in orthochlorophenol at 25 ° C) is 0.40 to 1.2.
Those having a range of 0 dl / g, preferably 0.60 to 0.90 dl / g are suitable for the content of the present invention.

The above-mentioned method is most preferably a method of coating during the production process of a polyester film and stretching the film together with the substrate. For example, the melt-extruded polyester film before crystal orientation is stretched about 2.5 to 5 times in the longitudinal direction, a surface to be continuously applied is subjected to corona discharge treatment, and a coating liquid is applied to the treated surface. The applied film is dried while passing through a stepwise heated zone, and the width of the
Stretched about 5 times. 150 to 250 more continuously
It is obtained by a method in which the crystal orientation is completed by being guided to a heating zone at ℃. The coating solution used in this case is preferably an aqueous solution in view of environmental pollution and explosion-proof properties. As a method of coating on the substrate film, a known coating method, for example, a reverse coating method, a gravure coating method, a rod coating method, a die coating method, a wire bar method, or the like can be used. Known additives, such as heat stabilizers, oxidation stabilizers, weather stabilizers, UV absorbers, organic lubricants, pigments, in the coating layer (easily adhesive layer) as long as the effects of the present invention are not impaired. , A dye, organic or inorganic fine particles, a filler, an antistatic agent, a nucleating agent, and the like.

Next, the method for producing the easily adhesive polyester film of the present invention will be described, but the present invention is not limited thereto. After drying the PET according to a conventional method, it is melt-extruded, and the extruded sheet-like melt is cooled and solidified to produce an unstretched PET film. 80 ~ 12
The film is heated to 0 ° C and stretched 2.0 to 5.0 times in the longitudinal direction to obtain a uniaxially oriented film. One surface of the film is subjected to a corona discharge treatment, and an aqueous coating material of the present invention diluted to a predetermined concentration with water is applied to the treated surface. Next, the coated film is stretched 2.5 to 5.0 times in the width direction while being heated to 90 to 140 ° C., and subsequently 160 to 240 ° C.
And heat-treated for 1 to 10 seconds.
During this heat treatment, a relaxation treatment of 3 to 12% may be performed in the width direction as necessary. By applying a coating agent according to the application on the coating layer side of the thus obtained easily adhesive polyester film, various ink printing such as magnetic recording material, cellophane ink, offset ink, ultraviolet curable ink, etc. It is preferably used as a base film for inorganic coatings such as for use in electrophotographic toners, for easy adhesion of chemical matte paints, for easy adhesion of diazo paints, and for vapor deposition.

[Method for Measuring and Evaluating Characteristic Values] The method for measuring characteristics and the method for evaluating effects in the present invention are as follows. (1) Adhesion The following paint is applied on a film (on a laminate of coating layers, on the coating layer) to form a coating layer, and a cellophane adhesive tape (Nichiban Co., Ltd.) is placed on the coating layer. After pasting and passing through a nip roll with a linear pressure of 50 kg / cm, 180
It peels off rapidly in the degree direction. The area of the coating layer adhered to the cellophane adhesive tape at that time was determined according to the following criteria. In the following criteria, [基準] or more was regarded as good adhesiveness. ◎: less than 10% ：: 10% or more and less than 20% △: 20% or more and less than 40% ×: 40% or more [paint composition] ・ Diferacoat CAD4301 (manufactured by Dainichi Seika Kogyo Co., Ltd.) 100 parts by weight ・ Sumiju -N75 (manufactured by Sumitomo Bayer Co., Ltd.) 1 part by weight The paint mixed in the above ratio was dried and then applied with a bar coater to a thickness of 6 μm and dried at 100 ° C. for 5 minutes.

(2) Moisture resistance The film provided with the coating layer prepared in the above (1) is heated at 50 ° C.
After being left for one week in a 90% RH atmosphere, the same adhesiveness evaluation as in the above (1) was performed.

(3) Blocking resistance The film having the easy-adhesion layer provided with the easy-adhesion layer surfaces superposed on each other (A) and the easy-adhesion layer surface and the biaxially oriented PET film superposed on each other (B) (overlap area) ： 3cm × 4
cm) with a load of 500 g / 12 cm ² at 50 ° C.
After standing for 24 hours in 5% RH, the shear stress at the overlapped portion was measured using a Tensilon tensile tester at a pulling speed of 20%.
It was measured at cm / min and judged according to the following criteria. ^{○: 0kg / cm 2 ~1kg /} cm 2 or less ^{△: 1kg / cm 2 ~3kg /} cm 2 or less ×: 3kg / cm ² or more

(4) Adhesion between easy-adhesion layer and substrate film A cross cut was made on the easy-adhesion layer (100 / c).
m ² ), a cellophane tape (manufactured by Nichiban Co., Ltd.) is adhered to the cross-cut surface, and pressure-bonded with a nipple having a surface pressure of 50 kg / cm ^2. The adhesion was evaluated to the extent that the adhesive layer was transferred to cellophane tape. When the peeled area was less than 5% (○), 5% or more and less than 10% (△), and 10% or more (x).

(5) Thickness of Coating Layer Using a transmission electron microscope model HU-12 manufactured by Hitachi, Ltd., an ultra-thin section of the laminated film was observed to determine the thickness.

(6) Surface roughness (Ra) According to JIS-B-0601, using a stylus type surface roughness meter BE-3E manufactured by Kosaka Laboratory Co., Ltd., cut-off 0.0
25 mm, measurement length 4 mm, center line average surface roughness Ra (μ
m) Measured.

(7) Charging Characteristics A base film without an easy-adhesion layer is wound around the surface of a rotating metal drum, and while rotating, a load of 255 g is applied to the end of the easy-adhesion layer of the film with the easy-adhesion layer laminated. Rub along the metal drum rotator for 5 seconds. Immediately after, the potential charged on the film was measured by a static electricity measuring device, and judged by the following criteria. (Charge amount) ：: +2.5 KV or more: -2.5 KV or more to +2.5 KV or less ×: -2.5 KV or less Static electricity measuring device: Statilon TH type manufactured by Shisido Electrostatic Co., Ltd. Measurement distance: 50 mm from the head opening Metal drum rotor: Number of revolutions; 860 rpm Dimensions: 65 mm width x 150 mm φ Measurement sample: 30 mm width x 300 mm length

[0028]

Next, the present invention will be described with reference to examples, but the present invention is not necessarily limited thereto. Example 1 0.4% of colloidal silica having an average particle size of 0.12 μm and 0.03% of calcium carbonate having an average particle size of 0.8 μm
PET pellets contained (intrinsic viscosity 0.62 dl / g)
After sufficiently dried in a vacuum, supplied to an extruder, melt-extruded at 280 ° C., filtered with a 10 μm-cut metal sintered filter, extruded through a T-type die into a sheet form, and dried.
It was wound around a cooling drum at ℃ and cooled and solidified. In order to improve the adhesion between the sheet and the surface of the cooling drum during this time, a wire electrode was arranged on the sheet side and a DC voltage of 6000 V was applied. The unstretched PET film thus obtained was heated to 95 ° C. and stretched 3.5 times in the longitudinal direction to obtain a uniaxially stretched film. One surface of this film was subjected to a corona discharge treatment in an air atmosphere, and the following easily coated water-based paint for forming an easily adhesive layer was applied to the treated surface by a gravure coating method. The coating thickness is 0.15 for the easily adhesive layer after biaxial stretching.
μm.

[Aqueous paint for forming an easily adhesive layer] 87.5 mol% of dimethyl terephthalate and 12.5 mol% of dimethyl 5-sodium sulfoisophthalate as the dicarboxylic acid component of the water-soluble copolymerized polyester, and ethylene as the glycol component The transesterification was carried out by heating with stirring in an autoclave using 0.09% of calcium acetate as a catalyst with respect to the acid component at a composition ratio of 100 mol% of glycol, and then trimethyl phosphate was used as a coloring inhibitor. After adding 04%, polycondensation was performed to obtain a water-soluble copolymerized polyester of the present invention. The obtained water-soluble copolymerized polyester had an intrinsic viscosity of 0.70 dl / g.

When this polymer was used as a 4.5% by weight aqueous paint, the transparency was excellent and the insoluble content was extremely small. 10% by weight of GPS based on the solid content of the water-based paint
The uniaxially stretched film to which this coating agent was applied
To the preheated zone heated to dry the water,
The clip is continuously gripped in a heating zone at 100 ° C. and stretched 3.5 times in the width direction, and then subjected to a heat treatment for 10 seconds in a heating zone at 225 ° C. while performing a 5% relaxation treatment in the width direction. An easily adhesive polyester film having a thickness of 20 μm and an adhesive layer thickness of 0.15 μm was obtained. Tables 1 and 2 show the evaluation results of this easily adhesive polyester film.
The adhesion of the various coating layers provided on the easy adhesion layer side of this film was extremely good, and there was no decrease in adhesion even under high temperature and high humidity, and the blocking resistance was also good. Further, the triboelectric charge also shifted to the plus side.

Example 2 As the dicarboxylic acid component of the water-soluble copolymerized polyester,
87.5 mol% of dimethyl terephthalate and 12.5 mol% of dimethyl 5-sodium sulfoisophthalate, while the glycol component is 80 mol% of ethylene glycol and an ethylene oxide adduct of bisphenol A (hereinafter referred to as B)
A water-soluble copolymerized polyester for forming an easily adhesive layer was obtained in the same manner as in Example 1 except that the composition ratio was set to 20 mol% (sometimes abbreviated as PA-EO). 20% by weight of GPS was added to the solid content of the aqueous solution of 4.5% by weight of the water-soluble copolymerized polyester, and a 20-μm thick easily-adhesive polyester film having an easily-adhesive layer thickness of 0.15 μm was prepared in the same manner as in Example 1. Obtained. The evaluation results of this easily adhesive polyester film are shown in Tables 1 and 2, and the adhesion of the various coating layers provided on the easily adhesive layer side of the film is extremely good, and the charging characteristics and the blocking resistance are also good. there were.

Example 3 87.5 mol% of dimethyl terephthalate and 12.5 mol% of dimethyl 5-sodium sulfoisophthalate as dicarboxylic acid components of the polyester copolymer of Example 1, while 70 mol% of ethylene glycol as a glycol component , Bisphenol S ethylene oxide adduct (hereinafter BPS-
Polymerization was carried out at a copolymerization ratio of 30 mol% (sometimes abbreviated as EO) to obtain a water-soluble copolymerized polyester of the present invention.
The resulting water-soluble copolymerized polyester had an intrinsic viscosity of 0.73.
dl / g. When this polymer was used as a 4.5% by weight aqueous paint, the transparency was excellent and the insoluble content was extremely small. In the same manner as in Example 1, 30% by weight of GPS was added to obtain a 20 μm-thick easily-adhesive polyester film having an easily-adhesive layer thickness of 0.15 μm. The results were, as shown in Tables 1 and 2, excellent in all of the adhesiveness, charging characteristics and blocking resistance.

Example 4 A coating liquid was prepared by adding 10% by weight of APS to the 4.5% by weight aqueous paint of Example 1 based on the solid content of the aqueous paint. In the same manner as in Example 1, a 20 μm-thick easily-adhesive polyester film provided with an easily-adhesive layer thickness of 0.15 μm was obtained. As a result, as shown in Tables 1 and 2, an easily adhesive polyester film having further improved adhesion was obtained.

Example 5 The thickness of the easily-adhesive layer was adjusted to 0. 4% by weight in the same manner as in Example 4 except that 10% by weight of MTS was added to the 4.5% by weight aqueous paint of Example 4 based on the solid content of the aqueous paint. 15 μm thick 20
A μm easily adhesive polyester film was obtained. As shown in Tables 1 and 2, an easily adhesive polyester film having good adhesion was obtained.

COMPARATIVE EXAMPLE 1 87.5 mol% of dimethyl terephthalate and 12.5 mol% of dimethyl 5-sodium sulfoisophthalate as dicarboxylic acid components of the polyester copolymer of Example 1, while 100 mol% of ethylene glycol as a glycol component 20 μm thick easily adhesive polyester having an easily adhesive layer thickness of 0.15 μm in the same manner as in Example 1 except that GPS was not added to a 4.5% by weight aqueous solution of a water-soluble copolymerized polyester polymerized at a copolymerization ratio of A film was obtained. As shown in Tables 1 and 2, the negative charge was strong and the adhesion of the magnetic paint was not improved.

Comparative Example 2 Polyester copolymer of Example 1 Copolymerization ratio of dicarboxylic acid component of 96 mol% of dimethyl terephthalate and 4 mol% of dimethyl 5-sodium sulfoisophthalate, while glycol component of 100 mol% of ethylene glycol To obtain a water-soluble copolymerized polyester. The solubility of this polymer was very poor, and many undissolved components remained until the end.
This coating solution was adjusted to 4.5% by weight, and a 20 μm-thick easily-adhesive polyester film having an easily-adhesive layer thickness of 0.15 μm was obtained in the same manner as in Example 1. However, uneven coating and surface roughness were observed. The film was badly worthy of evaluation. The results are shown in Tables 1 and 2.

Comparative Example 3 Polyester Copolymer A dicarboxylic acid component containing 45 mol% of dimethyl terephthalate and 55 mol% of dimethyl 5-sodium sulfoisophthalate, while a glycol component containing 100 mol% of ethylene glycol was used as a water-soluble polymer. A copolymerized polyester was obtained. This polymer was very soluble and had good transparency. This coating solution was adjusted to 4.5% by weight, and the thickness of the easily-adhesive layer was adjusted to 0.
An easily adhesive polyester film having a thickness of 20 μm and a thickness of 15 μm was obtained. The results are shown in Tables 1 and 2, and the adhesion was good, but the blocking resistance was very poor.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

The film of the present invention is a water-soluble copolymerized polyester comprising a specified amount of an aromatic dicarboxylic acid component, an ester-forming alkali metal salt of sulfonic acid and a glycol component on at least one surface of a polyester film, And an easy-adhesion polyester film obtained by laminating a coating solution obtained by adding a specific amount of a specific silane coupling agent to the solid content of the water-soluble copolymerized polyester as an easy-adhesion layer, having excellent water solubility and excellent It has adhesiveness, charging characteristics, and blocking resistance, and can be preferably used for a base film used for a magnetic recording material or the like.

In particular, the easily adhesive polyester film of the present invention has the following advantages: (1) It has excellent adhesion to various coating layers, and its adhesion is extremely small even under high temperature and high humidity. (2) Since it has excellent blocking resistance and good storage properties under high temperature and high humidity, it can be suitably used for various applications, particularly for easy adhesion films such as magnetic materials requiring surface smoothness. (3) Addition of a silane coupling agent converts triboelectric charge from negative to positive charge, which is offset by negative charge generated during the processing process and approaches closer to plus or minus zero potential, so it is effective in explosion-proof measures when using solvents etc. It is.

(56) References JP-A-2-171243 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 27/00-27/42 C08J 7/04

Claims (3)

(57) [Claims] At least one side of a polyester film has at least 50 mol% of an aromatic dicarboxylic acid component and 5 to 5 mol%.
An easily-adhesive polyester film comprising a water-soluble copolymerized polyester comprising an acid component comprising an ester-forming sulfonic acid alkali metal salt compound and a glycol component, wherein a layer comprising a silane coupling agent is laminated. 2. The water-soluble copolymerized polyester (A) /
The solid content mixing weight ratio of the silane coupling agent (B) is
2. The easily adhesive polyester film according to claim 1, wherein (A) / (B) is from 99/1 to 1/99. 3. The silane coupling agent is an alkoxysilane having at least one selected from an epoxy group, an amino group and a methyl group as an organic functional group.
Or 2) an easily adhesive polyester film.