JPH07195644A - Laminated polyester film - Google Patents

Abstract

PURPOSE:To improve adhesiveness and blocking resistance by providing an easy adhesive layer consisting of hydrophilic polyester having a specific compsn. and fine particles of silicon oxide with a specific average particle size on the single surface or both surfaces of a polyester film. CONSTITUTION:A laminated polyester film is formed by laminating an easy adhesive layer based on hydrophilic polyester wherein a 2,6-naphthalene dicarboxylic acid component is 20mol% or more of the total dicarboxylic acid component and a glass transition point is 60-90 deg.C and fine particles with an average particle size of 30150nm of silicon oxide on the single surface or both surfaces of a polyester film. The wt. ratio of fine particles of silicon oxide and polyester constituting the easy adhesive layer must be set to 5/100-45/100. Since polyester having a high secondary transition point is used in the easy adhesive layer and the fine particles with a specific particle size of silicon oxide are used, the bonding strength of the easy adhesive layer to magnetic paint is high and the blocking of a primer layer and a magnetic layer at the time of the coating with magnetic paint is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film, and more specifically, it has an easily adhesive layer on one side or both sides,
The present invention relates to a laminated polyester film suitable as a base material for film-shaped or sheet-shaped magnetic disks and magnetic cards.

[0002]

2. Description of the Related Art A thermoplastic polymer such as polyethylene terephthalate or a copolymer thereof, polyethylene naphthalate or a copolymer thereof, or a blend thereof with a small proportion of another resin is melt-extruded to form a film. Is known. It is also known that the polyester film heat-fixed after biaxial stretching is superior in heat resistance, gas barrier property, electrical property and chemical resistance to a film made of other resin. However, since the surface is highly crystallographically oriented, the surface has high cohesiveness,
Poor acceptance of paints, adhesives, inks, etc.

Even when a magnetic recording medium such as a floppy disk is prepared by providing a magnetic layer on a polyester film, the adhesiveness between the polyester film and the magnetic layer is similarly insufficient.

Therefore, for example, a method of applying a polyester primer to a polyester film to improve the adhesiveness to the magnetic layer has been proposed. This method has an advantage that the primer can be applied in the polyester film forming step and, as a result, the primer can be applied in an atmosphere with less dust, and also the collectability of the polyester film used once is excellent.

However, a polyester film coated with a polyester-based primer is apt to cause blocking and has been impractical for practical use. In particular, when manufacturing a floppy disk, a primer layer is provided on both sides of the polyester film, and once the magnetic layer is provided on one side of the film and the film is wound, the primer layer and the magnetic layer tend to block adhesion during the aging process. was there.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated polyester film which is excellent in adhesiveness and blocking resistance and can be suitably used especially for magnetic recording media such as floppy disks. Another object of the present invention is to provide an easy-adhesion layer capable of substantially suppressing blocking between a primer layer (easy-adhesion layer) and a magnetic layer in a step of applying a magnetic coating material when manufacturing a magnetic recording medium. To provide a laminated polyester film.

[0007]

According to the present invention, the 2,6-naphthalenedicarboxylic acid component accounts for 20 mol% or more of the total dicarboxylic acid component on one side or both sides of the polyester film and has a glass transition temperature of 60. -90 ° C and hydrophilic polyester (A) and average particle size of 30-
The presence of an easy-adhesion layer containing 150 nm of silicon oxide fine particles (B) as a main component and having a weight ratio of the silicon oxide fine particles (B) to the polyester (A) of 5/100 to 45/100. A featured laminated polyester film is provided to achieve the objects of the invention described above.

In the polyester film of the present invention, polyester having a high second-order transition point is used as a binder in the easy-adhesion layer, and since silicon oxide fine particles having a specific particle size are used, the adhesive force to the magnetic paint is high and, in addition, the magnetic paint is applied. It is possible to eliminate the tendency of the primer layer (easy adhesion layer) and the magnetic layer to block in the step.

Hereinafter, the present invention will be described in detail, and further objects, configurations and advantages and effects of the present invention will be apparent.

In the present invention, the polyester constituting the polyester film provided with the easy-adhesion layer is a polyester mainly composed of an aromatic dicarboxylic acid component and a glycol component, for example, polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly ( Examples thereof include 1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalene dicarboxylate, and copolymers thereof. When forming a film from this polyester, a small proportion of another resin may be mixed.

In the polyester (A) which is a component of the easily adhesive layer of the laminated polyester film of the present invention, the 2,6-naphthalenedicarboxylic acid component accounts for 20 mol% or more, preferably 30 to 100 mol% of the total dicarboxylic acid component. It has a glass transition temperature of 60 to 90 ° C, preferably 65 to 85 ° C, and is hydrophilic.

As the dicarboxylic acid component other than the 2,6-naphthalenedicarboxylic acid component that can be contained in the polyester (A), there are terephthalic acid, isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid and 2,6-naphthalene. Dicarboxylic acid, 4,4′-diphenyldicarboxylic acid, adipic acid, sebacic acid, decane dicarboxylic acid,
Examples thereof include succinic acid, 5-sodium sulfoisophthalic acid, 2-potassium sulfoterephthalic acid and trimellitic acid monopotassium salt.

The polyester (A) may contain, in addition to the above dicarboxylic acid component, a trivalent or higher polyvalent carboxylic acid component such as trimellitic acid, trimesic acid and pyromellitic acid in a small proportion that does not substantially cause crosslinking. it can. It may also contain an oxycarboxylic acid component such as p-hydroxybenzoic acid.

As the glycol component of polyester (A), ethylene glycol, propylene glycol, 1,
3-propanediol, 1,4-butanediol, 1,6
-Hexanediol, neopentylene glycol, 1,
4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A / alkylene oxide adduct, diethylene glycol, triethylene glycol,
Polyethylene glycol, polypropylene glycol,
Examples thereof include polytetramethylene glycol, sodium dimethylolethylsulfonate, potassium dimethylolpropionate and the like.

The polyester (A) may contain a trivalent or higher polyvalent hydroxy component such as glycerin or trimethylolpropane in a small amount so that crosslinking is not substantially caused. Moreover, the polyester (A) has a hydroxyl group and a carboxyl group in the molecule, such as dimethylolpropionic acid.
The polyfunctional compound components contained in the number of 1 or more can be contained in a small amount such that crosslinking is not substantially caused.

The glass transition point of polyester (A) is 60.
~ 90 ° C, preferably 65-85 ° C. The polyester (A) is hydrophilic to the extent that it can be dissolved, emulsified or dispersed in water.

The glass transition point of the polyester (A) can be easily adjusted to the above range by appropriately selecting the dicarboxylic acid component, the glycol component and other components and the composition ratio of these components. Further, the polyester (A) can be made hydrophilic by introducing a dicarboxylic acid component having a hydrophilic group such as an alkali metal sulfonate or an arlyca metal carboxylate or a polyalkylene glycol component. For example, a dicarboxylic acid component having an alkali metal sulfonate (5-sodium sulfoisophthalic acid, 2-potassium sulfoterephthalic acid, etc.) is 0.02 to 18 of all dicarboxylic acid components.
Hydrophilicity can be achieved by occupying about mol%.

The intrinsic viscosity (measured in an orthochlorophenol solvent at 35 ° C.) of the polyester (A) is 0.4 to 0.0.
It is preferably 9 dl / g.

By using the above polyester (A) as a binder resin for the easy-adhesion layer, a laminated polyester film having excellent blocking resistance and adhesion to the magnetic layer can be obtained. Also, polyester (A)
Aqueous liquid can be easily prepared from

The silicon oxide fine particles which are a component of the easy-adhesion layer have an average particle diameter of 30 to 150 nm, preferably 40 to 140 n.
m is used. By blending such silicon oxide fine particles, the laminated polyester film of the present invention is provided with slipperiness and is excellent in blocking resistance and magnetic properties when used as a magnetic recording medium.

In the easy-adhesion layer, silicon oxide fine particles (B)
Weight ratio of polyester (A) to 5/100 to 45/1
00, preferably 10/100 to 30/100.
Excessive blending of silicon oxide fine particles is not preferable because shavings are generated.

The laminated polyester film of the present invention has a thickness of 4 to 150 μm, and the easily adhesive layer has a thickness of 0.01 to
It is preferably 0.2 μm.

Such a laminated polyester film of the present invention is produced by applying an aqueous coating solution containing polyester (A) and silicon oxide fine particles (B) onto the polyester film and drying. A preferred manufacturing method is a method in which polyester is melt-extruded to first prepare an unstretched film, which is stretched in the machine direction, coated with the above coating solution, further stretched in the transverse direction, and subsequently heat-treated. The finally obtained biaxially oriented polyester film had a crystal dissolution heat of 4c measured by a scanning calorimeter (DSC) in a nitrogen stream at a temperature rising rate of 10 ° C./min.
It is preferably crystallized to have a value of al / g or more.

If necessary, the above-mentioned aqueous coating solution may include an inorganic filler other than silicon oxide fine particles, an organic filler, a lubricant, a colorant, a pigment, a surfactant, a stabilizer, an antistatic agent,
It may contain dispersants, small amounts of other resins and the like.

[0025]

EXAMPLES The present invention will be specifically described below based on examples. Each characteristic of the film was measured by the following method. (1) Adhesiveness The evaluation paint was applied to the surface of the polyester film easy-adhesion layer with a Meyer bar so that the thickness after drying was about 4 μm, and 1
Dry at 00 ° C for 3 minutes. After that, it was aged at 60 ° C. for 24 hours, and then adhered to Scotch tape No. 600 (manufactured by 3M Co.) with a width of 12.7 mm and a length of 15 cm so that air bubbles did not enter it. JIS C2701 (1975)
Level it out with the manual load roll described and bring it into close contact, and cut into a tape width. The strength when the tape is peeled 180 degrees is measured.

[Evaluation paint] Urethane resin Nipporan 2304 25 parts Vinyl chloride / vinyl acetate resin S-REC A (manufactured by Sekisui Chemical Co., Ltd.) 50 parts Dispersant Resion P (manufactured by Riken Vitamin) 1 part Magnetic agent CTX-860 ( Toda Chemical Co., Ltd.) 500 parts was dissolved in a chimertier ketone / toluene / cyclohexanone mixed solvent to make a 40% solution, which was then subjected to 2 with a sand glider.
Disperse in time. Then, 25 parts (corresponding to solid content) of the cross-linking agent Coronate L is added and well stirred to obtain a magnetic coating material.

(2) Blocking property The surface (un-cured) coated with the magnetic coating on the surface of the easy-adhesion layer and the surface of the easy-adhesion layer are put together, left at 50 ° C. and 30 kg / cm ² for 10 hours, and then peeled to observe the situation. . A: No stickiness at all. B: Slightly sticky and has peel resistance. C: Adhesion occurs and transfer occurs.

[Example 1] Intrinsic viscosity 0.64 dl / g
An unstretched film of polyethylene terephthalate (measured in an orthochlorophenol solvent at 35 ° C.) was stretched 3.6 times in the machine direction, and then an aqueous coating solution was applied to both sides. This aqueous coating liquid is 2,6-naphthalenedicarboxylic acid (accounting for 45 mol% of all acid components) -isophthalic acid-5-sodium sulfoisophthalic acid-ethylene glycol-bisphenol A / propylene oxide adduct copolymerized polyester A- 1 (Tg = 78 ° C.), silicon oxide fine particles B-1 having an average particle diameter of 75 nm and polyoxyethylene nonylphenyl ether were contained in a total amount of 4% by weight, and the weight ratio of these three components was 80:10:10. . After coating, while being dried, it was stretched in the transverse direction by 4.0 times and heat-treated at 220 ° C. to obtain a film having a thickness of 75 μm and a coating thickness of 0.04 μm.
The characteristics of this film are shown in Table 1.

Comparative Example 1 Example 1 was repeated except that the procedure for forming a coating film was not performed in Example 1, and the properties of the film obtained are shown in Table 1.

Examples 2-7, Comparative Example 2 Example 1 was repeated except that the composition of the coating and the thickness of the coating were changed as described in Table 1. The characteristics of the obtained film are shown in Table 1.
Shown in.

In Table 1, polyester A-2,
The polyester A-3 and the silicon oxide fine particles B-2 are as follows. Polyester A-2 terephthalic acid-isophthalic acid-5-potassium sulfoterephthalic acid-ethylene glycol-eopentylene glycol copolymer (Tg = 45 ° C.) Polyester A-3 terephthalic acid-isophthalic acid-5-sodium sulfoisophthalic acid- Ethylene glycol-1,4-butanediol copolymer (Tg = 19 ° C.) Silicon oxide B-2 Average particle size 88 nm

[0032]

[Table 1]

[0033]

Since the laminated polyester film of the present invention is excellent in adhesiveness and blocking resistance, it can be suitably used for magnetic recording media such as floppy disks.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G11B 5/704 // C08G 63/189 NME

Claims (1)

[Claims] 1. A hydrophilic polyester having a 2,6-naphthalenedicarboxylic acid component accounting for 20 mol% or more of the total dicarboxylic acid component on one or both sides of the polyester film and having a glass transition temperature of 60 to 90 ° C. (A) and silicon oxide fine particles (B) having an average particle diameter of 30 to 150 nm as a main component, and the silicon oxide fine particles (B)
The weight ratio to the polyester (A) is 5/100 to 4
A laminated polyester film having an easily adhesive layer of 5/100.