JPH0858044A - Laminated polyester film - Google Patents

Abstract

PURPOSE: To provide a laminated polyester film whose antistatic property or conductivity has been improved to be excellent particularly under a low humidity atmosphere, wherein quantities of peeling electrification and running frictional electrification of the film can be reduced excellently. CONSTITUTION: At least one face of a polyester film is coated with a water base liquid which contains a composition consisting of 20-95wt.% of a binder resin (A) and 5-80wt.% of a particle (B) obtained by forming a coat of polypyrrole on a surface of a fine particle having an average particle diameter of 1-5000nm. It is dried and stretched so as to form a laminated polyester film.

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 particularly to a conductive laminated polyester film which has excellent electric conductivity even in a low humidity atmosphere and is useful for electronic materials, graphic materials, magnetic recording materials and the like.

[0002]

Polyester films, especially polyethylene terephthalate films, are used for magnetic recording media, packaging materials,
Widely used in photographic materials and graphic materials.
The untreated polyester film is inferior in adhesiveness to various coating agents, and a thin film is particularly difficult to slip and has a problem that winding work is difficult. Therefore, many coating agents have been developed and proposed in order to solve these problems. However, due to the formation of the coating layer, electrification occurs during peeling of the polyester film and during running, causing various troubles. In order to prevent this trouble, a method of adding an antistatic agent to the coating agent has been proposed, but in the coating layer, the antistatic agent separates from the binder resin and bleeds, which adversely affects the coating layer surface. I often gave it.

Further, when an antistatic agent is added, the antistatic property in a low-humidity atmosphere often deteriorates. As a method for improving this, a coating layer (coating film) containing carbon black is used. A method for forming the layer is known. However, carbon black is liable to agglomerate, and troubles due to agglomerated particles are likely to newly occur, and the present application is limited. Further, JP-A-3-192161 proposes a means for coating the pigment surface with tin oxide, but it has not been possible to obtain sufficient conductivity.

Further, as a conductive polymer, polypyrro-
However, the polypyrrole has a drawback that it is brittle when formed into a coating film, and it is difficult to form a continuous coating film particularly when it is stretched after being applied to a film.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems of the prior art and improve the antistatic property or conductivity, and particularly the antistatic property or conductivity is excellent in a low humidity atmosphere. Another object of the present invention is to provide a laminated polyester film which is excellent in peeling electrification of the film and reduction of running friction electrification.

[0006]

The object of the present invention is to:
According to the present invention, firstly, a coating film of polypyrrole is formed on the surface of (A) 20 to 95 wt% of binder resin and (B) fine particles having an average particle diameter of 1 to 5000 nm on at least one surface of a polyester film. This is achieved by a laminated polyester film prepared by applying an aqueous liquid containing a composition of 5 to 80 wt% of particles, and then drying and stretching.

In the present invention, a binder is used in the coating agent.
Since the particles containing a film of polypyrrole formed on the surface of fine particles of a specific particle size are included together with the resin, the shape and size of the particles can be freely designed in addition to the conductive characteristics, and the specific gravity of the particles can be adjusted. Has the advantage. In addition, the binder
It has an advantage that it is easy to form a continuous film even if it is stretched after coating depending on the selection of the resin.

The present invention will be described in detail below.

In the present invention, the polyester constituting the base film is a crystalline linear polyester comprising a dicarboxylic acid component and a glycol component. The dicarboxylic acid components include terephthalic acid, isophthalic acid, 2,
6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4'-diphenyldicarboxylic acid, adipic acid,
Examples include sebacic acid and dodecanedicarboxylic acid. Among these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are particularly preferable. Furthermore, a trifunctional or higher polyvalent carboxylic acid component (for example, trimellitic acid) can be copolymerized in a small amount within a range where the polymer is substantially linear. As the glycol component, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1 , 6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, bisphenol, 1,
4-Cyclohexane dimethanol, polyethylene glycol, polytetramethylene glycol and the like can be exemplified. Of these, ethylene glycol is particularly preferable. Furthermore, a trifunctional or higher functional polyol component (for example,
Pentaerythritol, etc.) can also be copolymerized in small amounts within a range where the polymer is substantially linear.

The polyester can be produced by a conventional method, but the average molecular weight is preferably 10,000 or more. As a lubricant in polyester,
For example, silica, alumina, kaolin, calcium carbonate,
Inert fine particles such as titanium oxide, graphite, carbon black, crosslinked silicone resin, melamine resin, crosslinked polystyrene and crosslinked acrylic resin can be contained. Further, if desired, an antioxidant, an antistatic agent, a colorant, a pigment, a fluorescent whitening agent, a plasticizer, a cross-linking agent, a lubricant, an ultraviolet absorber and the like can be added.

In the present invention, the polyester film can be produced by conventionally known methods and conditions, or by methods and conditions accumulated in the art. For example, the polyester can be produced by melt-extruding the polyester into a film, rapidly cooling and solidifying the unstretched film, and stretching and heat setting the unstretched film. The stretching treatment is carried out in at least one direction, but it is preferably carried out in biaxial directions. Stretching is usually carried out at a temperature not lower than the second-order transition point of polyester at a draw ratio of 2 times or more, preferably 3 times or more in each direction.

In the present invention, in the process of producing such a polyester film, an aqueous liquid is applied, followed by drying and stretching. Preferably, the longitudinally stretched film is coated with an aqueous liquid and stretched in the transverse direction while being dried. If necessary, it is re-stretched further in the machine direction or the transverse direction and further heat-treated to obtain a laminated polyester film. The thickness of the polyester film is preferably 2 to 300 μm.

In the present invention, a polyester resin can be preferably exemplified as the binder resin (A) constituting the aqueous liquid. Examples of the dicarboxylic acid component of the polyester resin include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid and hexahydroterephthalic acid. . As the glycol component, ethylene glycol,
Propylene glycol, 1,3-propanediol,
1,4-butanediol, neopentyl glycol,
1,5-Pentanediol, 1,6-Hexanedio-
, Diethylene glycol, dipropylene glycol,
Triethylene glycol, alkylene oxide adduct of bisphenol A, hydrogenated bisphenol A alkylene oxide adduct, 1,4-cyclohexanedimethanoe
Examples thereof include polyethylene glycol, polytetramethylene glycol and the like. Furthermore, a component containing a sulfonate group for imparting hydrophilicity to the polyester resin, for example, 5-Na sulfoisophthalic acid, 5-Na
It is preferable to copolymerize K sulfoisophthalic acid or the like.
In addition, a trifunctional or higher polyvalent carboxylic acid component and a polyol component can be copolymerized in a small amount. Examples of such components include trimellitic acid, pyromellitic acid, dimethylolpropionic acid, glycerin and trimethylolpropane.

In the present invention, as the binder resin (A) other than the polyester resin, for example, a polyurethane resin, an acrylic resin, an epoxy resin, a vinyl resin, an acrylic modified polyester, a polyether, a water-soluble resin or the like is used. I can.

In the present invention, the particles (B) as a component constituting the aqueous liquid are particles having a polypyrrole film formed on the surface of fine particles having an average particle size of 1 to 5000 nm. Examples of the fine particles include silica, tin oxide, alumina, titanium oxide, kaolin, zinc oxide, calcium carbonate, silicon carbide, iron oxide, ferrite, calcium fluoride, crosslinked polystyrene, crosslinked acrylic resin, melamine resin, crosslinked silicone resin and the like. Can be illustrated. The average particle size of these fine particles is 1 to 5000 nm, and particularly preferably 3 to 500 nm. If the average particle size is less than 1 nm, it is difficult to form particles, while if it exceeds 5000 nm, the stability of the particles is lowered and the abrasion resistance of the coating film is deteriorated.

A polypyrrole film is formed on the surface of the fine particles. As a method for forming the film, for example, coating by a polypyrrole solution treatment, polymerization of the pyrrole on the surface of the fine particles and the like can be mentioned. You can The thickness of the polypyrrole coating is 0.1 to 2000 nm, especially 0.5 to 300 n.
It is preferably m. If this thickness is less than 0.1 nm, the conductive properties will be insufficient, while if it exceeds 2000 nm, the stability of the particles will decrease and the abrasion resistance of the coating film will deteriorate, which is not preferable.

The polypyrrole is a homopolymer of a pyrrole or a pyrrole derivative, or a pyrrole or a pyrrole.
It is possible to use a copolymer whose main component is a phenol derivative. As the pyrrole derivative, a ring-substituted product of pyrrole, N-
Substitutes can be exemplified. As this substituent,
For example, an alkyl group, a hydroxyl group, a sulfonate group, etc. can be mentioned.

The ratio of the binder resin (A) to the particles (B) is such that the component (A) is 20 to 95 wt% and the component (B) is 5 to 80.
wt%. In particular, the component (A) is preferably 50 to 93 wt% and the component (B) is 7 to 50 wt%. If the proportion of the component (B) is less than 5 wt%, the conductive properties will be insufficient, while if it exceeds 80 wt%, the coating film will become brittle and the abrasion resistance will deteriorate.

In the aqueous liquid, in addition to the components (A) and (B), other fillers, surfactants, antioxidants, antistatic agents, colorants, pigments, optical brighteners, plasticizers, A crosslinking agent, a lubricant, an ultraviolet absorber, etc. can be contained.

The aqueous liquid is usually used at a solid content concentration of 1 to 30 wt%, but a concentration of 2 to 20 wt% is particularly preferable. The aqueous liquid may contain a small amount of organic solvent.

In the present invention, the aqueous liquid is coated on at least one side of the polyester film (base film) with a coater such as a gravure coater or a river roll coater.
It is applied by a coater, a die coater or the like. The WET coating amount is preferably 1 to 20 g / m 2, and particularly preferably 2 to 12 g / m 2. After coating, it is preferably stretched in the transverse direction while being dried, but if necessary, it is further stretched in the longitudinal direction and / or the transverse direction and heat-treated.

The thickness of the coating layer after drying is 0.005 to 3 μm.
m, particularly 0.015 to 1 μm is preferable.

The laminated polyester film thus obtained is, for example, 1 × 10 ⁶ to 1 × 10 ¹² even in a low humidity atmosphere.
It has a surface resistivity of (Ω / □), is excellent in antistatic properties and conductivity, and is useful as a base film for magnetic recording media, packaging materials, photographic materials, graphic materials and the like.

[0024]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to the following examples. The evaluation in the present invention was performed by the following method.

(1) Surface Specific Resistance The surface specific resistance of the laminated polyester film (coating layer surface) was measured by a vibration capacitance type potentiometer TR-84M (manufactured by Takeda Riken) after being left at 23 ° C. × 50% RH for 24 hours. To do.

(2) Scratch resistance of coating layer A laminated polyester film is slit into a width of 1/2 inch, and the coating layer surface is brought into contact with a fixing pin having a diameter of 6 mm while being 1
0 m / min. The following ranking is performed by observing the amount of shavings adhering to the fixed pin after running 100 m at the speed of. A: Almost no accumulation. B: Some accumulation. C: A considerable amount is accumulated.

[Example 1] Polyethylene terephthalate having an intrinsic viscosity of 0.62 was melted, cast on a rotating cooling drum, and rapidly solidified to give an unstretched film. It was stretched 3.4 times. Then, on one side of the obtained longitudinally stretched film, terephthalic acid-5-Na
Sulfoisophthalic Acid-Ethylene Glycol-Diethylene Glycol-Neopentyl Glycol-based Polyester (A-1) 46 wt%, 5 nm thick polypyrrole film is formed on the surface of crosslinked acrylic resin fine particles having an average particle size of 8 nm. A 3 wt% aqueous solution of a composition (solid content) consisting of 42 wt% of the particles (B-1) and 12 wt% of polyoxyethylene nonylphenyl ether was added to a gravure roll coater.
Was applied. Subsequently, while being dried, the film was stretched 3.3 times in the transverse direction and heat-treated to obtain a laminated stretched polyester film having a thickness of 22 μm. The coating layer thickness of this film is 0.68μ
It was m. The characteristics of the film are shown in Table 1.

Comparative Example 1 Particles (B-
The same procedure was performed except that 1) was not added. Table 1 shows the results.

[Examples 2-8, Comparative Examples 2-4] Example 1
In the same manner, except that the composition of the coating material and the thickness of the coating layer were changed as shown in Table 1. Table 1 shows the results.

[0030]

[Table 1]

The symbols in the table are as follows. [B-2]: Particles in which a polypyrrole film having a thickness of 8 nm is formed on the surface of silica fine particles having an average particle diameter of 12 nm. [B-3]: Particles having a 6 nm-thick poly (3-hexylpyrrole) coating formed on the surface of titanium oxide fine particles having an average particle diameter of 9 nm. [B-4]: Particles having a 3 μm-thick polypropylene film formed on the surface of crosslinked acrylic resin fine particles having an average particle size of 8 μm.

[0032]

EFFECTS OF THE INVENTION According to the present invention, the antistatic property or the conductivity is improved, and the antistatic property or the conductivity is excellent especially in a low humidity atmosphere, and the peeling charge of the film and the reduction of the running friction charge amount are excellent. A laminated polyester film can be provided.

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Claims (4)

[Claims] 1. A polyester film having 20 to 95 wt% of (A) binder resin on at least one side and (B) 5 to 80 wt% of particles having a polypyrrole film formed on the surface of fine particles having an average particle size of 1 to 5000 nm. A laminated polyester film produced by applying an aqueous liquid containing a composition consisting of, then drying and stretching. 2. The fine particles of particles (B) are silica, tin oxide,
The laminated polyester film according to claim 1, which is at least one kind of fine particles selected from alumina, titanium oxide, crosslinked polystyrene and crosslinked acrylic resin. 3. The thickness of the polypyrrole coating is 0.1 to 2.
The laminated polyester film according to claim 1, which has a thickness of 000 nm. 4. The laminated polyester film according to claim 1, wherein the binder resin (A) is a polyester resin.