JP2002113831A - Method for producing adhesive laminated polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyester film which uses the recovered waste film effectively, has a flat surface, is excellent in adhesion and electromagnetic conversion characteristics, and is useful for a magnetic recording medium, etc. SOLUTION: In the method for producing the adhesive laminated polyester film comprising a polyester layer (A), a polyester layer (B) of 0.01-0.02 μm in surface roughness Ra which is laminated on one surface of the layer (A) by a co-extrusion method, a polyester layer (C) of 0.01 μm or below in surface roughness which is laminated on the other side of the layer (A) by the co- extrusion method, and an adhesive resin layer (D) which is coated with a polyester aqueous solution and formed on the surface of the layer (C), the layer (A), the layer (B), and the layer (C) are biaxially oriented, and the layer (D) is oriented at least uniaxially. The laminated polyester film is crashed, and the recovered chips obtained by melt-extrusion are used as a raw material for extruding the layer (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an easily-adhesive laminated polyester film, and more particularly, to a method for effectively utilizing a collected waste film, which is excellent in easy adhesion, excellent in adhesion on a flat surface, and excellent in electromagnetic characteristics. The present invention relates to a method for producing an easily-adhesive laminated polyester film useful for magnetic recording media and the like having excellent conversion characteristics.

[0002]

2. Description of the Related Art Biaxially stretched polyester films are widely used as base films for video tapes.
However, in recent years, the base film has been required to have a flat surface, and reduction in cost has been an issue.

In order to reduce the cost, a method of using a collected waste film for the intermediate layer as a laminated film of three-layer co-extrusion has been studied as an effective method. In this case, however, if the surface of the surface layer is flattened, The film handling property in the film forming process is lost. In particular, when three layers are formed by using two kinds of polymers, it is difficult to make the surface of the surface layer both flat and handleable. In general-purpose grades of video tapes, a backcoat for imparting runnability is often not provided, so it is necessary to impart runnability by forming fine irregularities on the film surface, but the runnability is reduced by flattening the surface. It was also difficult to simultaneously satisfy the adhesiveness with the magnetic paint.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to form a three-layer co-extruded film in which the intermediate layer can be made of a polymer obtained from a collected waste film, and has a flat surface and easy adhesion and lubricity. An object of the present invention is to provide a method for producing a polyester film.

[0005]

The present invention has the following structure to achieve the above object. Polyester layer (A), surface roughness Ra laminated on one surface of layer (A) by coextrusion method is greater than 0.01 μm and 0.02 μm
The following polyester layer (B), a polyester layer (C) having a surface roughness Ra of 0.01 μm or less laminated on the other surface of the layer (A) by a co-extrusion method, and a surface of the layer (C) It comprises an easily adhesive resin layer (D) applied by application of an aqueous polyester solution, and the layers (A), (B) and (C) have been subjected to a biaxial stretching treatment. D) is a method for producing an easily-adhesive laminated polyester film that has been stretched in at least one direction, and the collected chips obtained by pulverizing the melt-extrudable laminated polyester film and forming the recovered chips in the layer (A). A method for producing an easily-adhesive laminated polyester film, which is used as a raw material for extrusion.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In the present invention, since a film layer having a rough surface is used for the intermediate layer (layer A) of the three-layer co-extruded film, there is an advantage that a polymer such as a collected debris film can be used freely. In order to maintain excellent electromagnetic conversion characteristics in audio, computer tapes, floppy (registered trademark) disks, etc., the roughness is reduced, and the decrease in film runnability in the film forming process due to flattening is reduced by an easily-adhesive primer layer (layer D). ).

In the present invention, the polyester constituting layers A, B and C is terephthalic acid, isophthalic acid, 2,6-
An aromatic dicarboxylic acid component such as naphthalenedicarboxylic acid and 4,4-diphenyldicarboxylic acid and a glycol component such as ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and 1,6-hexanediol are used. Crystalline aromatic polyester that is composed, as specific examples polyethylene terephthalate,
Preferred are polyethylene-2,6-naphthalenedicarboxylate and the like. Naturally, copolymerized polyesters such as the above components are also included.

These polyesters may contain organic or inorganic fine particle fillers as required. Examples of such a filler include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, carbon black, silicon carbide, tin oxide, acrylic resin particles, polystyrene resin particles, melamine resin particles, and silicone resin particles. sell. In addition to the fine particle filler, a colorant, an antistatic agent, an antioxidant, an organic lubricant, a catalyst, other resins, and the like can be optionally added.

In the present invention, the surface roughness Ra of the polyester layer (A) is preferably more than 0.01 μm and 0.025 μm or less. Especially 0.012-0.02μ
m is preferable. In the present invention, this layer (A) is formed from collected waste of the easily adhered laminated polyester film. The easily-adhesive laminated polyester film can be used even if it is colored or contains a fine particle lubricant. When the surface roughness Ra of the layer (A) exceeds 0.25 μm, there is an influence of the roughness on the surface layer or it is large, which is not preferable.

In the present invention, the polyester layer (B) laminated on one surface of the layer (A) by coextrusion has a surface roughness Ra of more than 0.01 μm and not more than 0.02 μm, preferably 0.011 μm or less. The polyester layer (C) laminated on the other surface by coextrusion has a surface roughness Ra of 0.01 μm or less, preferably 0.008 μm.
It is as follows. When the surface roughness Ra of the layer (B) is 0.01 μm or less, the slipperiness decreases. On the other hand, if the surface roughness of the layer (C) exceeds 0.01 μm, the electromagnetic conversion characteristics decrease, which is not preferable.

In the present invention, the easily adhesive resin layer (D) applied on the surface of the layer (C) is a layer containing polyester as a main component.

The polyesters include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4-diphenyldicarboxylic acid, phenylindanedicarboxylic acid, adipic acid, sebacic acid, Polycarboxylic acid components such as Na sulfoisophthalic acid and trimellitic acid, and ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 1,6-cyclohexanedimethanol, glycerin, It is an easily adhesive polyester composed of a polyhydroxy compound component such as methylolpropane, dimethylolpropionic acid, and an alkyl oxide adduct of bisphenol A, and is used as an aqueous solution, aqueous dispersion, or emulsion.

The easily-adhesive resin layer (D) can contain other resins, antistatic agents, organic and inorganic fillers, coloring agents, surfactants, ultraviolet absorbers, etc., in addition to the above polyester.

In the present invention, in the coextruded laminated film comprising the polyester layer (A) and the polyester layers (B) and (C), the thickness of the intermediate layer (A) is 2 to 15 μm.
m, more preferably 8 to 14 μm. The thickness of the layers (B) and (C) as the surface layer is 0.1 to 13 μm.
m, more preferably 0.2 to 3 μm. The thickness of the layer (B) may be different from that of the layer (C).
Any method can be used for the co-extrusion method for forming the laminated film. Conventional methods and conditions such as biaxial stretching can be adopted.

In the present invention, the easily-adhesive resin layer (D) is prepared by applying an aqueous coating solution containing a component for forming the layer to the surface of the layer (C) of the co-extruded laminated film, followed by drying and stretching. This coating is applied to an unstretched film, a uniaxially stretched film, a biaxially stretched film and the like. Of these, it is preferable to apply the film to a uniaxially stretched film stretched in the machine direction. After that, transverse stretching, and in some cases, re-longitudinal stretching and re-lateral stretching are also performed. The aqueous coating liquid is used in any form such as an aqueous solution, an aqueous dispersion, an emulsion and the like. As a coating method, a conventionally known method can be used.

The solid content of the coating solution is preferably 10% by weight or less, particularly preferably 1 to 6% by weight. The thickness of the resin layer (C) is preferably 0.01 to 0.1 μm.

The easily adhesive resin layer (C) in the present invention acts as a layer for imparting lubricity during the film forming step or during the secondary coating step, and after the secondary coating step, for example, the magnetic layer It has excellent adhesive action.

[0018]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” means parts by weight. Each characteristic value was measured by the following method.

1. Surface roughness Ra According to JIS B0601, using a high-precision surface roughness meter SE-3FAT manufactured by Kosaka Laboratory Co., Ltd., the radius of the needle is 2 μm.
m, magnification of 200,000 times at a load of 30 mg, cut-off of 0,0.
Under the condition of 08 mm, the chart is drawn, a portion of the measured length L is extracted from the film surface roughness curve in the direction of the center line, the center line of the extracted portion is set as the X axis, and the direction of the vertical magnification is set as the Y axis. When the roughness curve is represented by Y = (x),
The value given by the following equation is expressed in μm.

[0020]

(Equation 1)

In this measurement, the reference length was set to 1.25 mm,
Measured and expressed as an average value.

2. Coefficient of friction According to ASTM D 1894-63, a static friction coefficient (μs) is measured by combining the front and back surfaces of the film with a slippery measuring device manufactured by Toyo Tester. However, the load is 1
kg.

3. Adhesive Strength The following evaluation paint is applied to the sample film with a Meyer 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. 600 (manufactured by 3M), 12.7 mm in width and 15 cm in length, are adhered so as to prevent air bubbles from entering, and the top of this is smoothed with a manual load roll described in JIS C2701 (1975), and cut into a tape width. The strength when this is peeled 180 degrees is measured.

[Evaluation paint] In terms of solid content, 25 parts of urethane resin Nipporan 2304 (manufactured by Nippon Polyurethane), polyvinyl chloride / vinegar resin Esrec A (manufactured by Sekisui Chemical) 50
Part ・ Dispersant Ratio P (manufactured by RIKEN Vitamin) 1 part ・ Magnetic agent CTX-860 (manufactured by Toda Chemical Co.)
Spread over time. Thereafter, 25 parts of coronate L (in terms of solid content) of a crosslinking agent is added, and the mixture is stirred well to obtain a magnetic paint.

Example 1 An unstretched film of polyethylene terephthalate (A-1) containing a calcium carbonate lubricant and having an intrinsic viscosity of 0.60 was stretched 3.5 times in the machine direction and 3.9 times in the transverse direction. The film was stretched and then heat-set at 220 ° C. to obtain a biaxially stretched film having a thickness of 13 μm. The surface roughness Ra of this film was 0.015 μm.

Further, the unstretched film of the polyester (A-1) is stretched 3.5 times in the machine direction, and both sides of the obtained machine-stretched film contain silicon oxide and have a secondary transition point of 25%.
Terephthalic acid, isophthalic acid, 5-K sulfoisophthalic acid, ethylene glycol, 1,4-butanediol, neopentyl glycol copolymerized polyester (89
wt%) and a polyethylene oxide / propylene oxide copolymer (11 wt%) in 3% aqueous dispersion (J).
Was applied 4 g / m ² and then stretched 3.9 times in the transverse direction.
Further, the film was heat-set at 220 ° C. to obtain a resin-coated biaxially stretched film having a thickness of 13 μm. This resin-coated biaxially stretched film was pulverized and melt-extruded to obtain a recovered chip.

The recovered chip is used as an intermediate layer. One side of the recovered chip contains an aluminum oxide lubricant, polyethylene terephthalate (B-1) having an intrinsic viscosity of 0.63, and the other side contains a silicon oxide lubricant. Three layers of polyethylene terephthalate (C-1) were coextruded to form an unstretched laminated film. This is stretched 3.5 times in the machine direction, 4 g / m ² of the aqueous dispersion (J) is applied to the surface of the layer (C), and then 3.9 times in the cross direction, and further heat-set at 220 ° C. After the treatment, a biaxially stretched laminated film having a thickness of 14 μm was obtained.
The thickness of the intermediate layer of this film is 12.5 μm, the thickness of the outer layer on the non-coated side is 1 μm, and the thickness of the outer layer on the coated side is 0.1 μm.
The Ra of the intermediate layer was 0.015 μm, the Ra of the outer layer on the non-coated side was 0.012 μm, and the Ra of the outer layer on the coated side was 0.004 μm. Table 1 shows the adhesive strength and the like of the application surface.

Examples 2 to 7 The procedure of Example 1 was repeated except that the thickness of each layer of the three-layer co-extruded film and the coating liquid were changed as shown in Table 1. Table 1 shows the results.

[Comparative Example 1] The procedure of Example 1 was repeated, except that the coating solution was not applied. Table 1 shows the results.

[0030]

[Table 1]

Kinds of coating solution: [Coating solution P] 2,6-naphthalenedicarboxylic acid containing silicon oxide, terephthalic acid, 5-Na sulfoisophthalic acid,
Except that ethylene glycol, diethylene glycol and neopentyl glycol copolymerized polyester were used, they were blended in the same manner as in the coating liquid (J) of Example 1.

[0032]

According to the present invention, an easily-adhesive laminated polyester film useful for a magnetic recording medium or the like which is excellent in adhesiveness on a flat surface and excellent in electromagnetic conversion characteristics by effectively utilizing the collected waste film. We can provide a method.

Continued on the front page F term (reference) 4F100 AA08 AK01D AK41A AK41B AK41C BA04 BA07 BA10A BA10D CA19 EH17 EH20A EH20B EH20C EH46D EJ30 EJ37D EJ38A EJ38B EJ38C GB41 JL11D JL16 JL16Y

Claims (1)

[Claims] 1. A polyester layer (A), having a surface roughness Ra laminated on one surface of the layer (A) by a co-extrusion method having a surface roughness Ra of 0.0
A polyester layer (B) larger than 1 μm and 0.02 μm or less, a polyester layer (C) laminated on the other surface of the layer (A) by coextrusion and having a surface roughness Ra of 0.01 μm or less, and the layer An easy-adhesive resin layer (D) coated on the surface of (C) by applying a polyester aqueous solution, and the layers (A), (B) and (C) are subjected to a biaxial stretching treatment. A method for producing an easily-adhesive laminated polyester film, wherein the layer (D) is stretched at least in a uniaxial direction, wherein the recovered chips are obtained by pulverizing the melt-extruded laminated polyester film. Is used as a raw material for extrusion of the layer (A).