JP2002206032A - Polyester film having low static electrification and ready adhesiveness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester film provided with a primer layer having excellent contact traveling properties with a heating roll and high adhesiveness and low electrostatic property. SOLUTION: This polyester film having low electrification and ready adhesiveness is characterized in that at least one side of a polyester film containing 0.01-2 wt.% of a lubricant having 0.005-2 μm average particle diameter in the polyester is provided with the primer layer consisting essentially of (A) a water- dispersible polyester resin copolymerized with >=0.01 mol% and <0.5 mol% based on the total acid components of a sulfonate metal base and (B) a polyethylene oxide/monoalkyl ester, having 0.005-1 μm thickness, the surface roughness of the primer layer is 0.002-0.01 μm average roughness of central line and traveling coefficients of friction of the surface of the primer layer under heating at 65 deg.C and 105 deg.C are 0.05-0.75.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film having low chargeability and high adhesiveness, and more particularly to a polyester film having excellent contact running property with a heating roll and having a high adhesiveness and a low chargeability. In particular, the present invention relates to a low-charge, easily-adhesive polyester film useful as a base material for a magnetic recording medium.

[0002]

2. Description of the Related Art Polyester films have excellent physical and chemical properties and are used in a wide range of applications (for example, magnetic recording media,
Graphic materials, printing materials, packaging materials, electronic materials, etc.). However, the polyester film has a high degree of crystallinity, and it is necessary to impart surface characteristics suitable for the application in order to sufficiently bring out the film characteristics.

As a means for imparting easy adhesion to a polyester film, an aqueous solution of an easily adhesive polyester resin, for example, an aqueous dispersion, has been conventionally applied to form an easily adhesive layer (primer layer).
Has been proposed and put into practical use. For example,
It is known to apply an aqueous liquid of a hydrophilic polyester resin in which a sulfonic acid salt group is introduced into a polymer molecule in an amount of 0.5 mol% or more. However, this hydrophilic polyester resin has a disadvantage that it has a low secondary transition point (Tg) and is inferior in wet heat resistance. Further, a surfactant is added for stabilizing the aqueous liquid or for stabilizing the coating process. However, this surfactant also has a problem that heat resistance is lowered and coating properties are poor.

In order to increase the secondary transition point (Tg) of the polyester resin, it is effective to introduce a rigid component, but in this case, the adhesive properties tend to decrease, and the hydrophilicity also decreases. Therefore, there is a problem that the solubility of the resin is reduced.

[0005] JP-A-63-115747 discloses that
(A) a water-insoluble polyester copolymer formed from a mixed dicarboxylic acid component containing 0.5 to 15 mol% of a dicarboxylic acid containing a sulfonic acid metal base based on all dicarboxylic acid components, and a glycol component; formula

[0006]

Embedded image _{HO- (R 1 O) n- (} R 2 O) m-H ( where, n, m is an integer of 6~1200, R _1, R ₂ is an alkylene group having 1 to 4 carbon atoms Arylene group, R ₁ ,
A layer having a mixture of copolymers represented by an alkylene or arylene group having at least one of R ₂ having 3 or more carbon atoms) is laminated on at least one surface of the film, and is transparent and antistatic. A thermoplastic resin film laminate having excellent properties is disclosed. However, the antistatic properties of this film laminate cannot be said to be sufficient, and the copolymer has a low HLB, so that the adhesive properties tend to deteriorate.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-charge, easily-adhesive polyester having excellent heat resistance, excellent running properties in contact with a heating roll, and high adhesion and low electrification. To provide a film.

[0008]

The present invention has the following configuration to achieve the above object.

The polyester has an average particle size of 0.005 to 0.005.
On at least one side of the polyester film containing 0.01 to 2% by weight of a lubricant of 2 μm, (A) 0.1% based on all acid components.
A water-dispersible polyester resin obtained by copolymerizing a sulfonic acid metal base-containing compound in an amount of from 01 mol% to less than 0.5 mol%, and a primer having a thickness of 0.005 to 1 μm, which is mainly composed of (B) polyethylene oxide monoalkyl ether The primer layer has a surface roughness of a center line average roughness of 0.002 to 0.01 μm and a running coefficient of friction of the primer layer surface at a temperature of 65 ° C. and 105 ° C. of 0. From 0.5 to 0.75.
Easy-adhesive polyester film.

In the present invention, the polyester constituting the polyester film is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyesters are substantially linear and have film forming properties, especially film forming by melt molding.

Examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalenedicarboxylic acid, isophthalic acid, diphenoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, anthracene dicarboxylic acid and the like. Can be mentioned.

Examples of the aliphatic glycol include polymethylene glycol having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, and the like;
Alicyclic diols such as cyclohexane dimethanol can be mentioned.

In the present invention, as the polyester,
Those containing alkylene terephthalate and / or alkylene naphthalate as a main component are preferably used.

Among these polyesters, in particular, polyethylene terephthalate, polyethylene-2,6-naphthalate, 80 mol% or more of the total dicarboxylic acid component is terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and 80% of the total glycol component. A copolymer in which at least mol% is ethylene glycol is preferred. At that time, 2 of all acid components
0 mol% or less can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid; cyclohexane-1, It may be an alicyclic dicarboxylic acid such as 4-dicarboxylic acid. In addition, 20 mol% or less of the total glycol component can be the above-mentioned glycol other than ethylene glycol. For example, hydroquinone, resorcin, 2,2-
Aromatic diols such as bis (4-hydroxyphenyl) propane; aliphatic diols having an aromatic ring such as 1,4-dihydroxydimethylbenzene; polyalkylene glycols (polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.) Oxyalkylene glycol) and the like.

Further, the polyester in the present invention includes:
For example, aromatic oxyacids such as hydroxybenzoic acid, ω-
It includes those obtained by copolymerizing an oxycarboxylic acid component such as an aliphatic oxyacid such as hydroxycaproic acid in an amount of 20 mol% or less based on the total amount of the dicarboxylic acid component and the oxycarboxylic acid component.

Further, in the polyester of the present invention, a tricarboxylic or polyfunctional polycarboxylic acid component or a polyhydroxy compound component, for example, an amount in a range of substantially linear, for example, 2 mol% or less based on the total acid component, for example, Copolymers of trimellitic acid, pentaerythritol and the like are also included.

The above polyesters are known per se and can be produced by a method known per se.

As the above-mentioned polyester, those having an intrinsic viscosity of 0.4 to 0.9 measured at 35 ° C. as a solution in O-chlorophenol are preferred.

It is necessary that the polyester of the present invention contains inert inorganic particles or crosslinked polymer particles alone or in any combination as a lubricant. Inert inorganic particles include kaolin, calcium carbonate, silica,
Aluminum sesquioxide and the like are preferred. As the crosslinked polymer particles, particles made of a crosslinked silicone resin, a crosslinked polystyrene resin, a crosslinked acrylic resin, or the like are preferable. These particles are usually used at the time of polyester production, for example, at any time during transesterification or polycondensation reaction in the case of transesterification, or at any time in the case of direct polymerization, preferably as a slurry in glycol. Add in. The average particle size of the lubricant needs to be 0.005 to 2 μm, more preferably 0.01 to 1.8 μm, and the addition amount needs to be 0.01 to 2% by weight. And 0.03 to 1.5% by weight
It is preferred that

The polyester film in the present invention is preferably a biaxially oriented film, and its thickness is preferably 3 to 20 μm. Further, the polyester film has a Young's modulus in the longitudinal direction of 600 kg / mm ^2.
As described above, the pressure is preferably 700 kg / mm ² or more. The upper limit of the Young's modulus is about 2000 kg / mm ^{2 although} it depends on the type of polyester. If the Young's modulus is less than 600 kg / mm ² , it is not preferable because a magnetic tape has poor contact with a magnetic head and electromagnetic conversion characteristics deteriorate.

In the present invention, the primer layer provided on at least one surface of the polyester film is prepared by copolymerizing (A) a sulfonic acid metal base-containing compound in an amount of 0.01 mol% or more and less than 0.5 mol% based on all carboxylic acid components. A primer layer containing water-dispersible polyester resin and (B) polyethylene oxide monoalkyl ether as main components.

The water-dispersible polyester resin (A) is
The sulfonic acid metal base-containing compound is copolymerized in an amount of 0.01 mol% or more and less than 0.5 mol%, preferably 0.04 to 0.3 mol%, based on all dicarboxylic acid components. When the copolymerization ratio of this compound is less than 0.01 mol%, the water dispersibility of the resin and the stability of the coating liquid become extremely poor, while when it is 0.5 mol% or more, the chargeability of the film is strong, The purpose of low chargeability cannot be achieved.

The sulfonic acid metal group-containing compound includes a dicarboxylic acid having a sulfonic acid group (for example, Na sulfonate, Li sulfonate, K sulfonate, ammonium sulfonate, polyalkylphosphine sulfonate, etc.), for example, 5-Na sulfoisophthalic acid,
Preferable examples include -K sulfoisophthalic acid, 5-Na sulfoterephthalic acid, and 5-K sulfoterephthalic acid.

The dicarboxylic acid component constituting the water-dispersible polyester resin (A) includes terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, and 4,4'-diphenyldicarboxylic acid. Acid, phenylindanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, etc., and the glycol components include ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, Examples thereof include 4-cyclohexanedimethanol, dimethylolpropionic acid, glycerin, trimethylolpropane, and an alkylene oxide adduct of bisphenol A. Two or more of these can be used.

The polyethylene oxide monoalkyl ether (C) has the following formula (2)

[0026]

Embedded image

Here, R is an alkyl group, and q is 3 to
The number is fifteen. An ether compound represented by
In the formula (2), the alkyl group for R is preferably a primary or secondary alkyl having 8 to 18 carbon atoms, and specific examples include octyl, lauryl, myristyl, pentadecyl, and stearyl. Among them, alkyl having 12 to 14 carbon atoms is particularly preferable. Further, q is preferably a number of 5 to 9. In the above formula (2), R
The alkyl group acts as a lipophilic component,

[0028]

Embedded image

Acts as a hydrophilicity imparting component. Therefore, although depending on the molecular weight of the alkyl group, those having a small degree of addition polymerization of ethylene oxide (in other words, those having a small q) have strong lipophilicity, whereas those having a large degree of addition polymerization (in other words, q having a small degree of addition) Larger ones) have strong hydrophilicity. In the balance between the two properties, R is 12 carbon atoms.
It is preferable that q is from 5 to 9 and an alkyl group of from 1 to 14.

In the present invention, the ratio (% by weight) of the water-dispersible polyester resin (A) and the polyethylene oxide monoalkyl ether (B) is from 95 to 70: 5 to 5: 3.
0, more preferably 90 to 75:10 to 25. If the proportion of the water-dispersible polyester resin (A) is more than 95% by weight, the coating properties will be poor, while if it is less than 70% by weight, the adhesion will be poor. When the content of polyethylene oxide / monoalkyl ether exceeds 30% by weight, the adhesiveness, blocking resistance and heat resistance are lowered, while when it is less than 5% by weight, poor coating properties are obtained. Further, the softening point of the primer layer is preferably higher than 120 ° C. from the viewpoint of heat resistance.

The primer layer of the present invention has a running friction coefficient of 0.05 to 0.7 when heated at 65 ° C. and 105 ° C.
5, preferably 0.10 to 0.65.
If the running friction coefficient is less than 0.05, the film is very slippery, and a trouble of a roll end face defect occurs when winding the film. In this case, wrinkles may be formed on the film, or the running film may meander. The polyester film may come into contact with a heating roll during a manufacturing process or a processing process. For example, at the time of longitudinal stretching or re-longitudinal stretching, the surface of the heating roll comes into contact with the film,
In addition, the surface of the high-temperature roll comes into contact with the film by calendering after the application of the magnetic paint. Therefore, in order to improve the handling characteristics in the process while being in contact with the roll surface at such a high temperature (60 ° C. or higher), it is necessary to lower the friction coefficient at a high temperature as described above.

In order to reduce the running friction coefficient at high temperatures,
In addition to selecting the composition and the amount ratio of the water-dispersible polyester resin (A) and the polyethylene oxide monoalkyl ether (B), the surface of the primer layer should have a center line average roughness of 0.002 to 0.01 μm. It is necessary, and preferably has a surface roughness of 0.004 to 0.006 μm. This center line average roughness is 0.0
If it is less than 02 μm, the hand-rigging property in the processing step is deteriorated, while if it is more than 0.01 μm, the electromagnetic conversion characteristics are deteriorated.

The primer layer is formed by applying a coating solution to at least one surface of an unstretched polyester film, a uniaxially stretched polyester film, or a biaxially stretched polyester film,
It is provided by drying. Of these, it is preferable to apply the film to a uniaxially stretched film stretched in the longitudinal direction. In this case, after application, horizontal stretching, and in some cases, re-longitudinal stretching or re-horizontal stretching can be performed. Stretching can be performed under conventionally known conditions and methods. For example, the stretching ratio is 2.5 times or more, preferably 3.0 times or more in each of the biaxial directions, and the area magnification is 8 times or more, preferably 8 to 30 times.
It is twice.

The solid content of the coating solution (primer coating solution) is preferably 30% by weight or less, more preferably 15% by weight or less. The solid content concentration is 0.5% by weight or more,
More preferably, it is at least 1% by weight. In addition to the water-dispersible polyester resin (A) and the polyethylene oxide / monoalkyl ether (B), the coating liquid may contain other components such as inert fine particles and a heat stabilizer, if desired.

The thickness of the primer layer (dried coating film) is 0.1 mm.
It is necessary that the thickness be from 005 μm to 1 μm.

The laminated polyester film thus obtained is excellent in adhesiveness, heat resistance, running properties and low chargeability.
Particularly, it is useful as a base material for a magnetic recording medium.

[0037]

EXAMPLES The present invention will be further described below with reference to examples. In addition, each characteristic value was measured by the following method.

1. Adhesiveness A paint for evaluation is applied to the polyester film (the surface of the primer layer) with a Mayer bar so that the thickness after drying becomes about 4 μm, and dried at 100 ° C. for 3 minutes. Thereafter, aging was performed at 60 ° C. for 24 hours. 6
00 (manufactured by 3M), a width of 12.7 mm and a length of 15 cm were adhered to prevent air bubbles from entering.
(1975) Using a manual load roll described in (1975), closely contact, and cut out to tape width. The peel strength at the time of 180 degree peeling is measured. ：: 50 g or more △: 30 g or more and less than 50 g ×: 30 g or less (Evaluation coating) 25 parts by weight of urethane resin Nipporan 2304 (manufactured by Nippon Polyurethane) in terms of solids 50 parts by weight of vinyl chloride / vinyl acetate resin ESREC A (manufactured by Sekisui Chemical) Dispersant 1 part by weight of Ratio P (manufactured by RIKEN Vitamin) 500 parts by weight of magnetic agent CTX-860 (manufactured by Toda Chemical) is dissolved in a mixed solvent of methyl ethyl ketone / toluene / cyclohexanone to make a 40% liquid and dispersed by a sand grinder for 2 hours. Thereafter, 25 parts by weight of coronate L (in terms of solid content) of a cross-linking agent is added and stirred well to obtain a magnetic paint.

2. Young's modulus A film is cut into a sample having a width of 10 mm and a length of 150 mm.
And a chart speed of 500 mm / min with an Instron type universal tensile tester. The resulting load
The Young's modulus is calculated from the tangent to the rising portion of the elongation curve.

3. Center line average roughness Ra Stylus type surface roughness meter (SE-3FA) manufactured by Kosaka Laboratory Co., Ltd.
Using T), a chart (film surface roughness curve) is applied under the conditions of a needle radius of 2 μm and a stylus weight of 30 mg. From the film surface roughness curve, a portion of the measured length L is extracted in the direction of the center line, the center line of the extracted portion is defined as the X axis, the direction of the vertical magnification is defined as the Y axis, and the roughness curve is defined as Y = f.
When represented by (X), Ra [μm] given by the following equation is defined as the center line average roughness of the film surface.

[0041]

(Equation 1)

4. Coefficient of friction during heating (μk) Measured as follows using the apparatus shown in FIG.
In FIG. 1, 1 is an unwinding reel, 2 is a tension controller, 3, 5, 6, 8, 9 and 11 are free rollers, 4 is a tension detector (entrance), and 7 is a stainless steel SUS304 fixing pin (outer shape). 5 mmφ), 10 is a tension detector (exit), 12 is a guide roller, 13
Indicates a take-up reel. The primer layer side of the polyester film cut to a width of 1/2 inch was attached to a fixing pin (surface roughness: 10 nm) heated to 65 ° C. or 105 ° C. by a heater at a 90 ° angle [θ = (90
/ 180) π (radian)] and move (friction) at a speed of 2 m / min per minute. Inlet tension T ₁ is adjusted by the second tension controller so as to be 30g, the outlet tension obtained while 40m run (Ti:
g) is detected. During this period, the maximum tension is set to T ₂ (g), and μk is calculated by the following equation.

[0043]

(Equation 2)

5. Chargeable polyester film (10μm × 500mm × 300
0 m) in an atmosphere of 23 ° C. × 75% RH at 150 m / m.
The roll is rewound at a speed of "in", and the amount of peeling charge of the roll is measured using a digital test electricity measuring instrument Model-203 manufactured by Hugle Electronics Co., Ltd. ：: less than 2.5 kv Δ: 2.5 to 5.0 kv ×: 5.0 kv or more

6 Evaluation of coatability When coating a primer coating solution on a film, the coated surface of the coated film is observed to visually determine whether the film is uniformly applied. ：: No spots and streaks are observed. Δ: Slight spots and streaks are observed. X: Spots and streaks are observed very frequently.

7. Coating liquid stability Store the primer coating liquid at 60 ° C. for 3 days and observe for any precipitate. ：: no precipitate is observed Δ: slight precipitate is observed ×: very large precipitate is observed

Example 1 After stretching an unstretched sheet of polyethylene terephthalate having an intrinsic viscosity of 0.62 by 2.3 times in the machine direction, a 2,6-naphthalenedicarboxylic acid component (40 mol%) and isophthalic Acid component (59.95
Mol%), 5-Na sulfoisophthalic acid component (0.05
Mol%), ethylene glycol component (70 mol%), 85 mol% of a water-dispersible polyester resin (number average molecular weight: about 23500) of a 4 mol adduct of bisphenol A propylene oxide (30 mol%), polyethylene oxide monoalkyl (Alkyl is a mixed alkyl of C12 to C14) ether (number average molecular weight: about 500, alkyl group: mixed alkyl of 12 to 14 carbon atoms) 15% by weight
Was applied with a roll coater. Then stretch 3.7 times in the horizontal direction while drying,
The film was further stretched longitudinally 2.3 times and heat-set at 220 ° C. to obtain a film having a thickness of 10 μm. The thickness of the primer layer was 0.015 μm. The surface roughness Ra of the film is 0.005 μm, and the Young's modulus in the longitudinal direction is 830 kg / m.
m ² . Table 1 shows the characteristics of the film.

[Examples 2 to 4, Comparative Examples 1 to 4] Example 1
In the above, the same procedure was performed except that the ratio of the applied material was changed as shown in Table 1. Comparative Example 2 uses polyethylene oxide / monoalkyl ether instead of polyethylene oxide / monoalkyl ether.
It is the same as Example 2 except that the polyoxypropylene copolymer is used as a surfactant. Table 1 shows the properties of the obtained film.

[0049]

[Table 1]

[0050]

According to the present invention, the easy-adhesion layer (primer layer) in the present invention can be heated by mixing a specific amount of sulfonic acid group-containing dicarboxylic acid in the polyester resin and mixing a specific amount of polyethylene oxide / monoalkyl ether. It has excellent running properties at the time of roll contact, has high adhesiveness and low chargeability, and exhibits excellent properties as a base material of a magnetic recording medium.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for measuring a running friction coefficient μk of a film surface.

[Explanation of symbols]

 1: Unwinding reel 2: Tension control 3, 4, 6, 8, 9, 11: Free roller 5: Tension detector (entrance) 7: SUS304 fixed rod 10: Tension detector (exit) 12: Guide roller 13: It is a take-up reel.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshifumi Osawa 3-37-19 Koyama, Sagamihara City, Kanagawa Prefecture Inside Teijin Limited Sagamihara Research Center (72) Inventor Hideaki Watanabe 3-37-19 Koyama, Sagamihara City, Kanagawa Prefecture No.F-term in the Sagamihara Research Center, Teijin Limited (Reference) 4F006 AA35 AB32 AB35 BA01 CA02 DA04 4F100 AK41A AK41B AK54B AL01B CA19A DE01A EJ37 GB41 JB05B JG03 JK07 JK14B JL11B YY00A YY00B 4J002 BC031CF031 FA086 FD172 FD176 GS01

Claims (6)

[Claims] 1. The polyester has an average particle size of 0.005.
(A) 0.01 mol% or more and less than 0.5 mol% of a sulfonic acid metal-base-containing compound based on the total acid components were copolymerized on at least one surface of a polyester film containing 0.01 to 2% by weight of a lubricant of 0.01 to 2 μm. A primer layer having a thickness of 0.005 to 1 μm containing water-dispersible polyester resin and (B) polyethylene oxide monoalkyl ether as main components is provided, and the surface roughness of the primer layer is
A center line average roughness of 0.002 to 0.01 μm; and a running friction coefficient of the primer layer surface at a temperature of 65 ° C. and 105 ° C. of 0.05 to 0.75. Adhesive polyester film. 2. The low-charge, easily-adhesive polyester film according to claim 1, wherein the alkylene of the polyethylene oxide monoalkyl ether (B) has 12 to 14 carbon atoms. 3. The low charging and easy adhesion according to claim 1, wherein the ratio (% by weight) of the water-dispersible polyester resin (A) and the polyethylene oxide monoalkyl ether (B) is 95 to 70: 5 to 30. Polyester film. 4. The thickness of the polyester film is 3 to 20.
The low-charge / easily-adhesive polyester film according to claim 1, which has a thickness of μm. 5. The low-charge, easily-adhesive polyester film according to claim 1, wherein the polyester film has a Young's modulus in the longitudinal direction of 600 kg / mm ² or more. 6. The low-charge, easily-adhesive polyester film according to claim 1, which is used as a base film of a magnetic recording medium.