JP3212828B2 - Laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film, and more particularly, to a magnetic recording material (for example, an audio tape,
Magnetic tape useful for magnetic tape such as video tape, magnetic disk such as floppy disk, telephone card, magnetic card such as prepaid card), electronic material, graphic material, plate making film, OHP film, packaging material, process material, etc. The present invention relates to a laminated film useful for a base film for use.

[0002]

2. Description of the Related Art Polyester films, especially polyester films using polyethylene terephthalate or polyethylene naphthalate, are widely used for magnetic recording materials such as magnetic tapes and for general industrial materials such as packaging materials, photographic materials and graphic materials. ing.

[0003] However, such a polyester film has a disadvantage that it is easily charged, and when the film is charged, there is a problem in that dust and dirt adhere to the surface of the film, causing quality problems. In addition, when an organic solvent is used in the film processing step, there is a problem that discharge from the charged film may cause ignition.

[0004] In order to solve the problem due to such charging, an antistatic coating containing a low molecular weight antistatic agent or a high molecular weight antistatic agent is applied on the surface of the polyester film to reduce the surface specific resistance of the film. A method has been proposed and put into practical use.

As the low molecular weight antistatic agent, for example, a surfactant type anionic antistatic agent such as a long-chain alkyl compound having a sulfonate group (JP-A-4-28728) is known. The polymer type antistatic agent includes a polymer having an ionized nitrogen element in the main chain (JP-A-3-255139, JP-A-Hei.
-288127, JP-A-6-172562) and sulfonate-modified polystyrene (JP-A-5-3).
No. 20390) is known.

However, in such an antistatic coating film using a low-molecular type antistatic agent, the antistatic agent moves in the coating film and accumulates at the interface to change the surface energy of the film. There are problems such as adversely affecting the adhesive properties when a top coat layer such as a magnetic layer, a release layer, and an easily adhesive layer is laminated on the film surface, and a problem that the antistatic property deteriorates with time. On the other hand, in the case of an antistatic coating using a polymer type antistatic agent, a large amount of an antistatic agent may be added to improve antistatic properties, or a thick antistatic coating may be used. It is not economical because it is necessary to form the film, and when a scrap film that does not become a product (for example, an end portion of a film cut and removed from a product) is collected and used as a recycled material for film production, a melted film cannot be formed. In this case, there is a problem that the coating film component contained in the recycled material is thermally degraded, and the obtained film is markedly colored and lacks practicality (recoverability is poor).

On the other hand, these polyester films are usually stored in a rolled state, and when the film is processed or the like, the film is unwound from the roll, and the film is moved in the longitudinal direction at a high speed in the processing step ( It is used while running. However, in a film in which the surface resistivity is simply reduced as in the prior art, it is difficult to suppress the charge (peeling charge) due to peeling of the films when the film is unwound from a roll, and the film is processed by this charge. There is a disadvantage that it is difficult to smoothly run the film in a processing step such as forming wrinkles or cutting in close contact with a roll for use.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and to improve the anti-peeling property when the film is unwound from a roll, the surface energy stability of the film, and the recoverability of the film. An object of the present invention is to provide an excellent laminated film.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to provide, according to the present invention, at least one side of a polyester film,
The structural unit (i) represented by the following formula (I) is added to 100 parts by weight of the copolymerized polyester (A) having a sulfonic acid salt group having a copolymerization ratio of 2 to 20 mol% and a secondary transition point of 70 to 160 ° C. Copolymer (B) comprising 60 to 98 mol%, structural unit (ii) represented by the following formula (II): 0 to 25 mol%, and structural unit (iii) represented by the following formula (III): 1 to 15 mol%
Is obtained by applying an aqueous coating liquid containing a composition containing 0.1 to 10 parts by weight of a coating film, and drying and stretching the coated film.

[0010]

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[0011]

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[In the formula (II), R ¹ and R ² are H or C
H ₃ ; X is a saturated hydrocarbon group having 1 to 6 carbon atoms]

[0013]

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[In the formula (III), R ¹ and R ² are H or CH
_3; R ³ is a carbon number 2-10 alkylene group; R ^4,
R ^5, R ⁶ is a saturated hydrocarbon radical H or carbons 1-5; R ⁷ represents a saturated hydrocarbon group having 1 to 5 carbon atoms. ]
Hereinafter, the present invention will be described in detail.

[Base Film] In the present invention, a polyester film is used as the base film. The polyester constituting the base film is a linear polyester comprising a dicarboxylic acid component and a glycol component.

Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid and the like. Among them, terephthalic acid and 2,6-naphthalenedicarboxylic acid are particularly preferred.

Examples of the glycol component include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, and 1,6-hexanediol. , Cyclohexanedimethanol, polyethylene glycol, polytetramethylene glycol, etc., and ethylene glycol is particularly preferred.

Among these polyesters, polyethylene terephthalate or polyethylene-2,6-naphthalate is a film having excellent mechanical properties such as a high Young's modulus and excellent thermal properties such as a good heat-resistant dimensional stability. It is preferable because it can be obtained.

The above-mentioned polyester may be a polyester obtained by copolymerizing the above-mentioned dicarboxylic acid component or glycol component in order to improve the adhesion between the polyester film and the coating film. A polyester obtained by copolymerizing a small amount of the above polyvalent compound in a range in which the polyester becomes substantially linear (for example, 5 mol% or less) may be used.

Such a polyester can be produced by a conventional method. Further, the intrinsic viscosity of the polyester is 0.45
The above is preferable because the mechanical properties such as high rigidity of the film are improved.

The above-mentioned polyester may contain organic or inorganic fine particles as a lubricant in an amount of, for example, 0.001 to 5% by weight in order to improve the slipperiness of the film. Specific examples of such fine particles include calcium carbonate, calcium oxide, amylnium oxide, titanium oxide, graphite, kaolin, silica, alumina,
Preferable examples include inorganic fine particles such as silicon oxide, zinc oxide, carbon black, silicon carbide, and tin oxide, and organic fine particles such as a crosslinked acrylic resin, a crosslinked polystyrene resin, a melamine resin, and a silicone resin.

In addition to the fine particles, a coloring agent, a known antistatic agent, an antioxidant, an organic lubricant, a catalyst, a fluorescent brightener, a plasticizer, a crosslinking agent, a slipping agent, an ultraviolet absorber, and other resins are required. It can be added according to.

The thickness of the polyester film is preferably 1 to 300 μm after stretching. Further, the light transmittance of the polyester film can be adjusted depending on the use of the film. For example, for applications requiring transparency, a polyester film having a light transmittance of 80% or more after stretching can be used.

The polyester film used in the present invention comprises:
It can be manufactured by a conventionally known method. For example, it can be produced by melting the polyester and casting it on a cooling drum to form an unstretched film, and then stretching the unstretched film in the machine direction and then in the transverse direction. Further, it can be stretched again in the machine direction and / or the transverse direction. The stretching treatment is performed at the secondary transition point (T
g) Preferably, the stretching is performed at a higher temperature by stretching at least twice, and more preferably at least three times in each direction. At this time, the area stretching ratio is preferably 8 times or more, more preferably 9 times or more. The upper limit of the area stretching ratio depends on the use of the film, but is preferably 35 times, and more preferably 30 times. After the stretching, heat treatment may be performed to complete the oriented crystallization.

[Copolyester (A)] The copolyester (A) used in the present invention is a linear polyester comprising a dicarboxylic acid component and a glycol component, and a component having a sulfonate group is contained in an amount of 2 to 2 per total acid component. It is a copolymerized polyester having a secondary transition point of 70 to 160 ° C., copolymerized by 20 mol%.

The dicarboxylic acid component includes terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4 '
-Diphenyldicarboxylic acid, adipic acid, sebacic acid,
Preferred examples include dodecanedicarboxylic acid, hexahydroterephthalic acid, and phenylindanedicarboxylic acid, and the glycol component is ethylene glycol.
Diethylene glycol, propylene glycol, 1,3
-Propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6
Preferred examples include -hexanediol, dipropylene glycol, triethylene glycol, bisphenol A-alkylene oxide adduct, hydrogenated bisphenol A-alkylene oxide adduct, and polyethylene glycol.

The component having a sulfonate group used in the copolymerized polyester (A) is a dicarboxylic acid component having a sulfonate group or a glycol component having a sulfonate group, for example, 5-Na sulfoisophthalic acid,
5-K sulfoisophthalic acid, 5-Na sulfoterephthalic acid, 5-Li sulfoterephthalic acid, 5-tributylphosphonium sulfoisophthalic acid, 1-Na sulfosuccinic acid, 3,3'-di-K sulfobisphenol A ethylene oxide adduct And the like.

The copolymerization ratio of the component having a sulfonate group is 2 to 20 mol% based on the total acid component. Even when only the dicarboxylic acid component having a sulfonate group or only the glycol component having a sulfonate group is used, Alternatively, both components (the sum of both components is 2 to 20 mol% based on the total acid component) may be used. If the proportion is less than 2 mol%, the dispersibility of the copolymerized polyester (A) in the aqueous coating liquid will be insufficient, and if it exceeds 20 mol%, the wet heat resistance will be reduced.

The secondary transition point of the copolymerized polyester (A) is from 70 to 160 ° C., preferably from 70 to 110 ° C. When the secondary transition point is lower than 70 ° C., the blocking resistance of the laminated film is inferior. When the secondary transition point is higher than 160 ° C., the low peeling chargeable coating film is easily shaved. Incidentally, the copolymerized polyester having a secondary transition point of 70 to 160 ° C. uses an aromatic dicarboxylic acid as a main component as a dicarboxylic acid component,
The glycol component can be obtained by selecting the secondary transition point so as to fall within the above range.

The average molecular weight of the copolymerized polyester (A) is preferably from 5,000 to 40,000, since the strength of the low-peelable charging coating film is improved.

[Copolymer (B)] The copolymer (B) according to the present invention comprises the structural unit (i) 6 represented by the above formula (I).
0 to 98 mol% of the structural unit (i) represented by the formula (II)
i) a copolymer of 0 to 25 mol% and the structural unit (iii) of 1 to 15 mol% represented by the formula (III), and a more preferable copolymerization ratio is such that the structural unit (i) is 80 to 95; Mol%, 2 to 15 mol% of the structural unit (ii) and the structural unit (ii)
i) is 2 to 10 mol%.

When the proportion of the structural unit (i) is less than 60 mol%, the heat-resistant melt stability (heat resistance) of the polyester composition is insufficient and the hue of the film deteriorates, and when it exceeds 98 mol%, adhesion to the top coat agent is caused. Is reduced. When the structural unit (ii) exceeds 25 mol%, the film has insufficient peeling charge resistance and heat resistance. When the structural unit (iii) is less than 1 mol%, the film has insufficient peeling charge resistance and 15 mol. %, The heat resistance of the film becomes insufficient.

The copolymer (B) is, for example, ethylene
Part or all of the acrylic acid component of the acrylic acid copolymer or ethylene / acrylic acid / acrylic acid ester (methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, etc.) copolymer, ethylene / methacrylic acid copolymer Part or all of the methacrylic acid component of the polymer or ethylene / methacrylic acid / methacrylic acid ester copolymer, and part of the crotonic acid component of the ethylene / crotonic acid copolymer or the ethylene / crotonic acid / crotonic acid ester copolymer Alternatively, it can be obtained by reacting all with N, N-dialkylaminoalkylamine to amidate and then performing a quaternary alkylation reaction.

For example, when the weight average molecular weight is 10,000 to
Water is added to a 500,000 ethylene-acrylate copolymer, and the mixture is reacted under high pressure and high temperature in an autoclave to decompose and decompose.
Produce 300,000 ethylene-acrylic acid copolymers or ethylene-acrylic acid-acrylate copolymers. Next, a part or all of the acrylic acid component of the ethylene / acrylic acid copolymer or ethylene / acrylic acid / acrylic acid ester copolymer and N, N-
Reaction with a dialkylaminoalkylamine (for example, N, N-dimethylaminopropylamine, N, N-diethylaminopropylamine, etc.) causes amidation, and finally a quaternary alkylation reaction to form a quaternary cation ion pair. By introduction, the copolymer (A) can be obtained. In the copolymer (B) thus obtained, the ethylene component is the structural unit (i), the acrylate component and the non-amidated acrylic acid component are the structural unit (ii), and the quaternary cation is obtained by the amidation and quaternary alkylation reaction. The acrylic acid component into which the ion pair has been introduced becomes the structural unit (iii). Specific examples of the structural unit (iii) include, for example, the following formulas (III-1) and (III-2).

[0035]

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[0036]

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The copolymer (B) further includes acrylamide, N-methoxymethylacrylamide, styrene,
Other monomer components such as vinyl chloride and sodium methacrylate can be copolymerized if they are in small amounts.

The weight average molecular weight of the copolymer (B) is arbitrary, but is preferably from 2,000 to 50,000 because the dispersibility in the aqueous coating liquid is good and the heat resistance is good. .

[Electrostatic Anti-Slip Coating Film] The anti-static anti-slip coating film of the present invention contains 0.1 to 10 parts by weight of the copolymer (B) per 100 parts by weight of the copolymerized polyester (A). Preferably, the composition is prepared by applying an aqueous coating solution containing a composition containing preferably 1 to 8 parts by weight, drying and stretching. If the blending amount of the copolymer (B) is less than 0.1 part by weight, the effect of suppressing peeling electrification is insufficient,
Adhesion of the coating film to the base film exceeding 10 parts by weight,
The abrasion resistance of the coating film decreases.

In order to improve the slipperiness of the film, the above composition has an average particle size of 0.01 to 0.01 as a lubricant.
Organic or inorganic fine particles of about 20 μm, for example, 0.00
It can be contained at a blending ratio of 1 to 5% by weight. Specific examples of such fine particles include silica, alumina, kaolin, calcium carbonate, calcium oxide, titanium oxide, graphite, carbon black, zinc oxide, silicon carbide,
Preferable examples include tin oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, crosslinked silicone resin particles, and the like.

In addition to the fine particles, coloring agents, known antistatic agents, antioxidants, organic lubricants (sliding agents), catalysts, plasticizers, crosslinking agents, ultraviolet absorbers, surfactants, coloring agents, pigments, fluorescent light A whitening agent, an ultraviolet absorber and the like can be added as needed.

Further, the above-mentioned composition includes an acrylic resin, an acrylic-modified polyester resin as a resin other than the copolymerized polyester (A) and the copolymer (B) for adjusting the adhesion between the coating film and the base film, A small amount of a polyurethane resin, an epoxy resin, a vinyl resin, a polyether resin, a water-soluble resin, or the like can be blended.

[Aqueous coating liquid] In the present invention, a coating film is applied using an aqueous coating liquid containing the above composition, and the solid content concentration of the aqueous coating liquid is preferably 1 to 30% by weight, particularly preferably Two
20% by weight is preferred. When the solid content concentration is within this range, the viscosity of the aqueous coating liquid becomes suitable for coating. The aqueous coating liquid used in the present invention can be used in any form such as an aqueous solution, an aqueous dispersion, and an emulsion. Further, the aqueous coating liquid may contain a small amount of a solvent.

[Coating of Coating] In the present invention, the coating is applied by coating the aqueous coating solution on at least one surface of the polyester film, drying by heating and stretching. As the method, any known coating method can be applied, for example, gravure coating, reverse roll coating, die coating, kiss coating, reverse kiss coating, offset gravure coating, Meyer bar coating, roll brushing, spraying A coating method, an air knife coating method, an impregnation method, a curtain coating method and the like can be applied alone or in combination. The WET application amount of the aqueous coating solution is 1 to 1 m ² of the running film.
20 g, especially 2 to 12 g, is preferred. It is preferable that the coating amount is in this range because drying becomes easy and coating unevenness hardly occurs.

The polyester film to which the aqueous coating solution is applied in the present invention is a stretchable polyester film, for example, an unstretched film which is obtained by melting a polyester by heating and forming the film as it is; ) Or a uniaxially stretched film stretched in either the transverse direction (width direction); a biaxially stretched film in which a longitudinally or transversely uniaxially stretched film is sequentially stretched in the transverse or longitudinal direction (more stretchable). Or a biaxially stretched film in which an unstretched film is simultaneously stretched in two directions (longitudinal and transverse) (further stretchable); a biaxially stretched film is heat-set and / or thermally relaxed (further stretchable) A biaxially stretched heat treatment film can be used.

The thickness of the polyester film is preferably 10 to 1000 μm for an unstretched film, 2 to 500 μm for a uniaxially stretched film, and 1 to 300 μm for a biaxially stretched film and a biaxially stretched heat-treated film.

When the aqueous coating liquid is applied to a uniaxially stretched film among the polyester films, particularly to a longitudinally uniaxially stretched film, the adhesiveness of the coating film becomes strong and a laminated film can be produced efficiently. preferable. For example, the polyester is hot-melted, extruded into a sheet and cooled to form an unstretched film, and the unstretched film is stretched in the longitudinal direction to form a uniaxially stretched film. Then, if necessary, the film is further stretched in the vertical and horizontal directions, and then heat-treated to produce a laminated film coated with a coating film.

The thickness of the applied coating film is 0.01 to 0.1 μm
m, particularly preferably 0.015 to 0.08 μm. If the thickness of the coating film is less than 0.01 μm, the effect of suppressing peeling electrification may be insufficient, and if it exceeds 0.1 μm, the coating film surface may be rough or easily shaved, which is not preferable.

[Drying and Stretching Conditions] After applying the aqueous coating liquid in the present invention, the drying temperature is preferably from 80 to 150 ° C., since the coating liquid can be dried quickly. The heating for drying can also serve as the heating in the process of stretching the polyester film. The heat treatment temperature of the polyester film can be set to 180 to 250 ° C.

[Laminated Film] The laminated film of the present invention can be made into a transparent laminated film having a light transmittance of 60% or more or a white laminated film having a light transmittance of less than 60% depending on the application. Use a polyester film having a light transmittance of 60% or more for the base film of the transparent laminated film, and use a white polyester film having a light transmittance of less than 60%, particularly 30% or less for the base film of the white laminated film. Is preferred.

The laminated film of the present invention is provided with a magnetic recording layer on at least one side of the laminated film and can be used for a magnetic tape.
The thickness of the coating is preferably 25 μm and the thickness of the coating is 0.01 to 0.1 μm.

[0052]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. Each characteristic value was measured by the following method. The average molecular weight in the examples means a weight average molecular weight.

1. Peeling electrification amount (peeling electrification resistance) Wound in a roll shape 1,000 mm, length 3,400 m
Was adjusted to a temperature of 20 ° C. and a humidity of 50% RH, and the amount of peeling charge of the film unwound from the roll at a speed of 75 m / min was measured with a potentiometer (Model 203 manufactured by Hugle Co., Ltd.). The peeling charge amount is about 10c from the film peeling position (the position where the film wound in a roll is peeled off from the roll and taken out) in the running direction of the film.
about 50mm from the surface of the film running at a distance of m
The measurement was performed with the detection end of the electrometer installed at a remote position. evaluated. A: Peeling charge amount is less than 1.5 KV (peeling charge resistance is particularly good) B: Peeling charge amount is 1.5 KV or more and less than 2.0 KV (peeling charge resistance is good) C: Peeling charge amount is 2. 0 KV or more (Practical problem due to poor peeling electrification resistance)

2. Surface energy (surface energy retention
E) Surface energy is E⁰dyne / cm blank film
One side of a polyester film without a film
5 kg / cm ^TwoLoad
In an atmosphere of 55 ° C. and 70% RH for 20 hours
After holding, peel off, sample film of blank film
Surface energy (E¹dyne / cm)
Surface energy from the measurement results obtained according to the following criteria.
Gee retention was evaluated. A: E¹/ E⁰≧ 0.950 (Surface energy
B: 0.950> E¹/ E⁰≧ 0.925 (Surface energy
C: 0.925> E¹/ E⁰ (Surface energy
The surface energy is JIS-K6768-1977.
By measuring the wetting index according to the wetting test method
I did.

3. Degree of coloring (film recoverability) A polyester film without a coating film was pulverized and melted at about 300 ° C with an extruder to form chips. Next, a melt film was formed using the obtained chip, and a biaxially stretched blank film having a thickness of 9 μm was prepared. On the other hand, the sample film coated with the coating film was pulverized,
And melted into chips. Next, a melt film was formed in the same manner using the obtained chip, and a biaxially stretched regenerated film having a thickness of 9 μm was prepared. The degree of coloring of the recycled film was compared with the degree of coloring of the blank film, and the sample film was evaluated according to the following criteria. Rank A: The degree of coloring is comparable to that of a blank film (good recoverability) Rank B: The film is slightly colored (slightly good recoverability) Rank C: The degree of coloring of the film is large and lacks practicality (poor recoverability)

[Example 1] Polyethylene terephthalate having an intrinsic viscosity of 0.62 was melted and cast on a cooling drum to form an unstretched film.
C. and stretched 3.5 times in the machine direction to obtain a uniaxially stretched film. Next, 11 mol% of terephthalic acid, 1 mol% of isophthalic acid, 69 mol% of 2,6-naphthalenedicarboxylic acid, 11 mol% of 4,4'-diphenyldicarboxylic acid and 5-mol Copolyester obtained using 10 mol% of K sulfoisophthalic acid, 85 mol% of ethylene glycol, 3 mol% of neopentyl glycol and 12 mol% of 1,4-cyclohexanedimethanol as glycol components (A1: Tg = 84 ° C.) , Average molecular weight = 20,500) 8
4 wt%, ethylene component 85 mol%, component represented by the ethyl acrylate component 7 mol% and the formula _{(III -1) (-CH 2 CH} - [(CONH) (CH 2) 3 N + (C
_{H 3) 3] [CH 3} SO 3 -]) of 7 mole% of the copolymer (B1) 5% by weight and polyoxyethylene nonylphenyl ether (C-1) a composition consisting of 10 wt% 4
A weight% aqueous coating solution was applied with a gravure coater. Next, after drying at 102 ° C., the film is stretched 3.8 times in the transverse direction at 106 ° C., and heat-treated at 224 ° C. to obtain a total thickness of 9 μm and a coating thickness of 0.1 μm.
A laminated film of 02 μm was obtained. Table 1 shows the characteristics of this film.

[Examples 2 to 8 and Comparative Examples 1 to 4] Laminated films were obtained in the same manner as in Example 1 except that the types and amounts of the copolymers or compounds were changed as shown in Table 1.
Table 1 shows the characteristics of these films.

[0058]

[Table 1]

In Table 1, [A1], [B1], [B
[2], [B3], [B4], [B5] and [C1] represent the following copolymers or compounds.

[A1]: Tereph as a dicarboxylic acid component
Tallic acid 11 mol%, isophthalic acid 1 mol%, 2,6-na
69 mol% of phthalenedicarboxylic acid, 4,4'-diphenyl
11 mol% of rudicarboxylic acid and 5-K sulfoisophthal
10 mol% of acid, ethylene glycol as glycol component
85 mol%, neopentyl glycol 3 mol% and
Using 12 mol% of 1,4-cyclohexanedimethanol
(Tg = 84 ° C., average
[B1]: 85 mol% of ethylene component, ethyl acrylate
7 mol% of the component and the component represented by the formula (III-1)
(-CH_TwoCH-[(CONH) (CH_Two)_ThreeN ⁺(C
H_Three)_Three] [CH_ThreeSO_Three ^-]) 7 mol% of copolymer
(Average molecular weight = 6,210) [B2]: 89 mol% of ethylene component, ethyl acrylate
5 mol% of the component and the component represented by the formula (III-2)
(-CH_TwoCH-[(CONH) (CH_Two)_ThreeN ⁺(C
H_Three)_Two(C_TwoH_Five)] [C_TwoH_FiveSO_Three ^-]) 6 mol
% (Average molecular weight = 5,920) [B3]: 88 mol% of ethylene component, ethyl acrylate
5 mol% of the component and the component (-) represented by the following formula (VI-2)
CH_TwoCH-[(CONH) (CH_Two)_FourN⁺(C
H_Three)_Three] [CH_ThreeSO_Three ^-]) 7 mol% of copolymer
(Average molecular weight = 6,850) [B4]: C₁₂H_{twenty five}SO_ThreeNa [B5]: a repeating unit represented by the following formula (VI-1)
(-CH_TwoCH- [CH _TwoN⁺(CH_Three)_Three] [C
l^-]) (Average molecular weight = 16,700)

[0061]

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──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 27/00-27/42 C08J 7/04

Claims (2)

(57) [Claims] 1. A polyester film having a sulfonic acid group-containing component copolymerized on at least one surface thereof in an amount of 2 to 20 mol% and having a secondary transition point of 70 to 160 ° C. 100 parts by weight of a copolymerized polyester (A), Structural unit (i) represented by the formula (I): 60 to 98 mol%, structural unit (ii) represented by the following formula (II): 0 to 25 mol%, and structural unit (iii) represented by the following formula (III) A laminated film provided with a coating film formed by applying an aqueous coating liquid containing a composition containing 0.1 to 10 parts by weight of a copolymer (B) in an amount of 1 to 15 mol%, drying and stretching. . Embedded image Embedded image [In the formula (II), R ¹ and R ² are H or CH ₃ ; X is a saturated hydrocarbon group having 1 to 6 carbon atoms.] [In the formula (III), R ¹ and R ² are H or CH ₃ ; R ³ is an alkylene group having 2 to 10 carbon atoms; R ⁴ , R ⁵ and R ⁶ are H or saturated carbon atoms having 1 to 5 carbon atoms. A hydrogen group; R ⁷ represents a saturated hydrocarbon group having 1 to 5 carbon atoms. ] 2. The polyester film has a thickness of 2 to 25.
μm, the thickness of the low peel electrification coating film is 0.01 to 0.1 μm
The laminated film according to claim 1, wherein the laminated film is used for a magnetic recording medium further provided with a magnetic layer on at least one surface thereof.