JP3095877B2 - Conductive film and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive film and a method for producing the same, and more particularly, to a conductive film having a low surface resistivity and exhibiting stable conductivity even at low humidity. The present invention relates to a conductive film useful for applications such as parts and a method for producing the same.

[0002]

2. Description of the Related Art Polymer films, especially polyester films, are excellent in mechanical properties, heat resistance, electrical properties, chemical resistance and the like, and are used for various purposes. However, a polymer film is easily charged, and a polyester film in particular has a high surface resistance value of 10 ¹⁵ to 10 ¹⁶ Ω / □ and is easily charged. Prone to trouble.

[0003] As a method for preventing the charge of a polymer film, for example, a polyester film, a method of applying an antistatic paint or a method of kneading an antistatic agent into a base polymer has been conventionally known. Examples of the antistatic agent include an ion conductive surfactant and TCN.
There are an electron conductive type using radical hopping such as a Q-TTF complex and a filler type electronic conductive type such as tin oxide-antimony oxide. However, the ion-conductive type antistatic agent has a large humidity dependency, and has a disadvantage that its effect is not exhibited in a low humidity atmosphere. There is a disadvantage that the pot life of the paint is short because it reacts with molecules. In addition, the conventional filler-type electron conduction type antistatic agent has a disadvantage that the surface of the coating layer is roughened due to the large particle size of the filler.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a conductive film based on a polymer film, especially a polyester film. An object of the present invention is to provide a conductive film having a surface resistivity, exhibiting stable electric conductivity, and having excellent flatness, and a method for producing the same.

[0005]

In order to achieve the above object, the present invention first comprises the following constitution.

On one or both surfaces of the polymer film, 1 to 99% by weight of conductive metal particles or conductive alloy particles having a primary particle size of 0.5 to 100 nm and a binder 99 to 1
Conductive coating comprising an aqueous dispersion of a composition containing 0.1 % by weight
The thickness obtained by applying is 0.002 to 0.
A conductive film having a coated conductive thin layer of 4 μm , wherein the surface specific resistance of the conductive thin layer is 1 × 10 ⁰ to 1 × 10 ¹³ Ω / □.

As the polymer film in the present invention,
The film is not particularly limited as long as it is a film having a large surface resistivity and easily charged, but a polyester film is particularly preferred.

Preferred polyesters are linear saturated polyesters synthesized from aromatic dibasic acids or their ester-forming derivatives and diols or their ester-forming derivatives. Specific examples of such polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, and poly (1,1).
Examples thereof include (4-cyclohexylene dimethylene) terephthalate, polyethylene-2,6-naphthalenedicarboxylate, and the like, and also include copolymers thereof and blends thereof with a small proportion of other resins.

The linear saturated polyester is melt-extruded, formed into a film by a conventional method, and oriented and crystallized by heat treatment to obtain a polyester film. The polyester film preferably has a crystal orientation such that the value measured by a scanning calorimeter in a nitrogen gas stream [at a heating rate of 10 ° C./minute] as a heat of crystal fusion is 4 cal / g or more.

As the conductive metal in the present invention, aluminum, scandium, titanium, vanadium,
Chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, lanthanoids, hafnium, tantalum,
Tungsten, renium, osmium, iridium, platinum, gold, tallium, lead, bismuth and the like can be exemplified. Of these, cobalt, nickel, copper, ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold and the like are desirable from the viewpoint of rust resistance. Further, as the conductive alloy, an alloy containing at least one of the above metals is preferable.

[0011] Particles of conductive metal or conductive alloy
The secondary particle size is 0.5 to 100 nm, preferably 0.5 to 2
0 nm. When the primary particle diameter of the conductive metal or conductive alloy is less than 0.5 nm, the particles become almost atomic and become unstable. When the primary particle diameter is larger than 100 nm, there is a problem that the surface of the polymer film coated with the conductive metal particles and the conductive alloy particles becomes rough. These primary particles are mostly agglomerated, forming secondary particles of 5 to 500 nm.

In order to obtain conductive metal particles and conductive alloy particles in the present invention, a salt of the metal or a mixture thereof and polyvinyl alcohol, polyvinylpyrrolidone, a water-soluble polyester resin, a water-soluble acrylic resin, a water-soluble urethane resin, etc. Using a water-soluble polymer such as methanol, ethanol, butanol, alcohols such as isopropyl alcohol, tetrahydrofuran, methyl ethyl ketone,
It can be obtained by refluxing in a low boiling water-soluble organic solvent such as acetone or a mixture of these alcohols, organic solvents and water.

Although this dispersion can be used as it is, an aqueous system containing no organic solvent is more preferable because of problems in working environment or equipment.

In the case where the dispersion is made to be an aqueous system containing no organic solvent, after adding water, the dispersion may be heated above the boiling point of the alcohol or the organic solvent to evaporate and remove the alcohol or the organic solvent. In this case, if the operation is performed under reduced pressure, an aqueous system completely free of an organic solvent can be obtained.

For example, when a nickel dispersion is obtained, nickel (II) chloride hexahydrate and polyvinyl alcohol are placed in ethanol and refluxed at 80 ° C. for 2 hours.
Further, when the nickel dispersion is an aqueous system containing no organic solvent, water is added to the nickel dispersion, and ethanol is evaporated at 90 ° C. or higher, whereby an aqueous conductive coating material can be obtained. The primary particle size of the nickel thus obtained is about 1 nm, which is practically preferable.

Examples of the binder in the present invention include, in addition to the water-soluble polymer, a water-dispersible acrylic resin, a water-dispersible urethane resin, a phenoxy resin, a water-dispersible polyester, a vinyl chloride resin, a vinyl acetate resin and the like. These can be used alone or as a mixture of two or more.

The composition ratio (weight% ratio) of the conductive metal or conductive alloy and the binder in the present invention is 1 to 99:
99-1.

The aqueous conductive coating composition containing solids having the above composition ratios may contain, if necessary, a lubricant, a surfactant, a dispersant, an antistatic agent, a stabilizer, a crosslinking agent, a catalyst, a defoaming agent, and a lubricant. Other additives such as an agent, a rust inhibitor and the like can be added. The solid content concentration in the aqueous conductive coating material can be freely selected, but is preferably selected from the range of 1 to 30% by weight.

The aqueous conductive coating composition can be applied to a polyester film in which crystal orientation has been completed, but is preferably applied to a polyester film before crystal orientation has been completed. Here, the polyester film before the completion of the crystal orientation is an unstretched film obtained by melting a polymer into a film as it is: a uniaxially stretched film in which the unstretched film is oriented in either the longitudinal direction or the transverse direction. : Further, a film stretched and oriented at a low magnification in two directions of a longitudinal direction and a transverse direction (a biaxially stretched film before being finally stretched in a longitudinal direction or a transverse direction to complete oriented crystallization).
Etc. are included. Of these, application to a uniaxially stretched film is preferred in terms of economy and cleanliness. That is, applying a conductive coating agent in the polyester film forming process is advantageous in terms of quality and cost.

The thickness of the final dried coating layer (conductive layer) is 0.002 to 0.4 μm, preferably 0.02 to 0.4 μm.
02~0.1μm Ru Der. If the thickness of the dried film of the coating layer (conductive layer) is less than 0.002 μm, a desired surface resistance cannot be obtained, and if the thickness is more than 0.4 μm, the surface after application becomes rough. In addition, as the coating layer becomes thicker,
There is a problem that the material cost increases. The coating is preferably performed by a roll coating method, a gravure coating method, a kiss coating method, or the like.

The polyester film coated with the aqueous conductive coating composition must be dried, and if necessary, subjected to stretching and heat treatment (heat setting treatment) to complete the crystal orientation. These treatments are conventionally known. It can be performed using the means, conditions, etc. The surface of the conductive layer on the polyester film thus obtained has a center line surface roughness (Ra) of 30 n.
m or less, more preferably 20 nm or less.

The conductive film of the present invention has a surface
Surface specific resistance is 1 × 10⁰~ 1 × 10 ¹³Ω / □, preferred
Is 1 × 10⁰~ 1 × 10^TenΩ / □. Therefore this guide
Conductive film as base film and conductive layer side as back side
(Back side) and magnetic tape (video tape, audio
If you make audio tape, computer tape, etc.)
It is possible to adjust the electrification of the magnetic tape during running.
Thus, an error due to charge adsorption can be prevented. Ma
Magnetic tape, magnetic disk
When making a disk, remove the conductive filler in the magnetic layer.
As a result, desirable effects such as an increase in the S / N ratio are expected.
The design can be made easier and the magnetic layer can be easily designed. Other substation
For general industrial use requiring antistatic and antistatic properties
Available.

[0023]

The present invention will be described in more detail with reference to the following examples. In addition, each physical property in an example is measured by the following method.

1. Surface specific resistance (ρ _s ) After leaving the film at 23 ° C. × 50% RH for 24 hours, the film is measured with a surface resistance measuring instrument Model 150 manufactured by TREK.

2. Center line 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, cutoff 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, and the center line X axis and the vertical magnification direction of the extracted portion are set to Y.
When the roughness curve is represented by Y = (x) as an axis, the value given by the following equation is represented in μm.

[0026]

(Equation 1)

In this measurement, four pieces were measured with a reference length of 1.25 mm, and the average value was expressed.

[0028]

Example 1 A four-necked flask was charged with 60 g of nickel (II) chloride hexahydrate, 3 g of polyvinyl alcohol, 100 g of ethanol, and 100 g of ion-exchanged water. By evaporating the ethanol at a temperature of not less than ° C, an aqueous conductive coating material containing nickel metal ultrafine particles dispersed therein was obtained. One drop of this coating material is applied to the copper mesh collodion film with a dropper and air-dried.
Observation of the particle diameter with a transmission electron microscope revealed that the primary particle diameter of the nickel metal ultrafine particles was about 1 nm and the secondary particle diameter was about 8 nm.

This coating composition was manually applied to a 75 μm-thick biaxially oriented polyethylene terephthalate film with a Meyer bar # 3, dried at 130 ° C. for 2 minutes, and dried to a thickness of about 0.4 μm.
Was obtained . Surface resistivity ρs of this film = 9 × 10 ⁵ Ω / □, center line surface roughness Ra
= 4.2 nm.

[0030]

Example 2 50% by weight of the coating composition of Example 1 and an aqueous dispersion of polyurethane (Superflex 30 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
0) The procedure was performed in the same manner as in Example 1 except that an aqueous conductive paint having a solid content of 5% was prepared using 50% by weight. The obtained film had ρ _s = 8 × 10 ⁶ Ω / □ and Ra = 4.0 nm.

[0031]

Comparative Example 1 The properties of the biaxially oriented polyester film before the application of the aqueous conductive coating agent in Example 1 were measured.
This film has ρ _s = 1 × 10 ¹³ Ω / □ or more , and Ra =
It was 4.0 nm.

[0032]

Comparative Example 2 The procedure of Example 2 was repeated except that the coating composition of Example 1 was changed to antimony-doped tin oxide. The obtained film was ρ _s = 1 × 10 ⁹ Ω / □, Ra
= 40.0 nm.

[0033]

Example 3 The same procedure as in Example 1 was carried out except that polyvinyl alcohol in Example 1 was changed to polyvinylpyrrolidone. The obtained film has ρ _s = 1 × 10 ⁶ Ω /
□, Ra = 4.2 nm.

[0034]

Example 4 Example 1 was repeated except that polyvinyl alcohol was changed to water-soluble polyester and ethanol was changed to tetrahydrofuran. The resulting film had ρ _s = 1 × 10 ⁶ Ω / □ and Ra = 4.2 nm.
Met.

[0035]

Example 5 The procedure of Example 1 was repeated, except that the nickel (II) chloride hexahydrate in Example 1 was changed to silver nitrate. The obtained film was ρ _s = 1 × 10 ⁸ Ω / □, Ra
= 4.0 nm.

[0036]

Example 6 The procedure of Example 1 was repeated except that nickel (II) chloride hexahydrate was changed to 30 g of palladium (II) chloride and 30 g of hexachloroplatinic acid (IV) hexahydrate. . The obtained film has ρ _s = 2 × 10 ⁷ Ω /
□, Ra = 4.1 nm.

[0037]

Example 7 Polyethylene terephthalate having an intrinsic viscosity of 0.65 measured in orthochlorophenol at 25 ° C. was melt-extruded on a rotating cooling drum maintained at 20 ° C. to form an unstretched film, and the unstretched film was then mechanically extruded. After stretching 3.6 times in the axial direction, Example 2 was applied to both sides of the film.
Was applied by a 4 g / m ² (wet) kiss coat method. Then stretched 3.6 times in the horizontal direction,
Heat treated at 5 ° C to make a 75μm thick double-sided film (film thickness
0.4 μm) A biaxially oriented polyester film was obtained. This film has ρs = 5 × 10 ⁷ Ω / □, Ra = 4.8 n
m.

[0038]

Example 8 The procedure of Example 1 was repeated except that a polyethylene-2,6-naphthalate film was used as the base film instead of the polyethylene terephthalate film in Example 1. The resulting film has ρ _s = 9
× 10 ⁵ Ω / □, Ra = 5.5 nm.

[0039]

According to the present invention, it has a low surface specific resistance even at low humidity, exhibits stable conductivity, and is excellent in flatness, especially for magnetic recording media and general industrial products. And a method for producing the same.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B32B 27/20 B32B 27/20 Z 27/36 27/36 // B29K 67:00 B29L 7:00 (56) References JP 62-108053 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (5)

(57) [Claims] 1. One or both sides of a polymer film
1 to 99% by weight of conductive metal particles or conductive alloy particles having a particle size of the secondary particles of 0.5 to 100 nm and a binder 99 to
Conductive coating comprising an aqueous dispersion of a composition containing 1% by weight
The thickness obtained by applying the agent is 0.002 to
A conductive film having a 0.4 μm coated thin conductive layer, wherein the thin conductive layer has a surface resistivity of 1 × 10 ⁰ to 1 × 10 ¹³ Ω / □. 2. The method according to claim 1, wherein the conductive thin layer has a thickness of 0.002 to 0.5 . 1
The conductive film according to claim 1, which has a surface roughness (Ra) of 30 nm or less. 3. The conductive film according to claim 1, wherein the polymer film is a polyester film. 4. On one or both sides of a polymer film, 1
Conductive particle size of the next particles 0.5~100nm metal particles or conductive alloy particles child1 99% by weight and the binder 99 to
The thickness obtained by applying a conductive coating agent comprising an aqueous dispersion of a composition containing 1% by weight is 0.002 to 0.002%.
A method for producing a conductive film, comprising forming a 0.4 μm-coated conductive thin layer. 5. The conductive film of claim 4 is applied to the polyester film before the crystal orientation is completed, and then dried, stretched and heat-treated to complete the crystal orientation to form a conductive thin layer. A method for producing a conductive film according to claim 4.