JP3071633B2 - Composite polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite polyester film, and more particularly, to a composite polyester film provided with a coating layer containing a charge control agent and having adjusted positive and negative charges and charging characteristics.

[0002]

2. Description of the Related Art Polyester films are widely used in magnetic tapes, electromagnetic disks, magnetic cards, packaging materials, photographic films, graphic materials, and process materials.
It is easy to be charged, and for example, peeling or frictional charging occurs during use, which tends to cause inconvenience, for example, foreign matter adsorption and discharge. This inconvenience also depends on whether the charge is positive or negative.

[0003] Polyester films are often surface-treated in order to impart secondary workability. For example, on one or both sides of the film, an easy-adhesive coating film, an easy-slip coating film, an easy-writing film, or an easy-printing film is provided. ing. In this case, depending on the coating film composition, the film may be positively charged or may be negatively charged. However, depending on the mode of use or application, negative charging may not be allowed even if positive charging is allowed. There are also opposite cases. In such a case, it is preferable that the composition of the coating film can be largely changed, but in many cases the composition cannot be changed from the viewpoint of other characteristics.

[0004] As a method of preventing electrification of a polyester film, a method of applying an antistatic paint and a method of kneading an antistatic agent into a base polymer are known.
In the conventional method, the type of charging is not changed or controlled, and the situation described above cannot be adequately dealt with.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a composite polyester film capable of adjusting the amount of charge on the film surface and the sign of the charge to realize a charge state suitable for the use of the film. .

[0006]

The present invention has the following arrangement to attain the object. At least one surface of the polyester film has a metal-containing azo compound and salicylic acid
From metal compounds of conductors and compounds represented by the following structural formula
A composite polyester film provided with a coating layer containing at least one selected charge control agent.

[0007]

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In the present invention, preferred polyesters constituting the polyester film are linear saturated polyesters synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene) terephthalate, polyethylene-2,6-naphthalenedicarboxylate, and copolymers thereof. Alternatively, blends thereof with a small proportion of other resins are also included.

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 usually shows 4 cal / g or more.

In the present invention, the coating layer is a coating layer containing a charge control agent. For example in addition to the binder resin in the coating layer of the charge control agent include known polyester, polyurethane, acrylic resins, epoxy resins, vinyl resins, polyether, polyamide, cellulose resin, polyvinyl alcohol, polysiloxanes, silane coupling agent ,
It contains silicone resin, phenol resin, butyral resin, phenoxy resin, styrene-based resin, vinyl chloride-based resin and the like as main components. One or more of these can be used.

The charge control agent may be a metal-containing azo compound.
Compounds, metal compounds of salicylic acid derivatives and the formation of the following structural formula
At least one charge control agent selected from the compound
You.

[0012]

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These are toner charge adjusting agents (charge control) used in electrophotographic copying machines, facsimile machines and the like.
Agent) or what is used
You. The charge control agent as those with negatively chargeable positively chargeable
There is. The metal-containing azo compound and the salicylic acid derivative gold
Specific examples of the genus compounds include the following compounds.

[0014]

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[0015]

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[0016]

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[0017]

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[0018]

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The charge control agent is preferably selected and used according to the purpose. These charge control agent can be used any amount, is contained 0.5-20% normal coating layer.

An antistatic agent (including a conductive agent) can be blended in the coating layer, if necessary, and is preferably blended. As this antistatic agent, carbon black,
Tin oxide, polyaniline, polypyrrole, electron conductive type conductive agent, alkyl sulfonate, alkylphenyl sulfonate, alkylene oxide copolymer, polyether sulfonate, ethosulfate, betaine, phosphate, alkyl sulfate, diphenyl ether Disulfonate, quaternary ammonium type, vinyl polymer containing sulfonate group, polystyrene sulfonate, cationic polymer containing quaternary nitrogen, vinyl polymer containing quaternary ammonium or amine base, metal complex, nitrogen-boron charge transfer complex And the like. One or more of these can be used. When an antistatic agent is blended, it is preferable that the surface resistivity of the coating layer be in the range of 10 ⁵ to 10 ¹² Ω / □.

It is advisable to optimize the type and amount of the charge control agent according to the type of the antistatic agent.

The coating layer may further contain other additives such as a filler and a stabilizer, if necessary.
The filler may be either an organic filler or an inorganic filler. Specific examples of such a filler include acrylic resin fine particles, silicone resin fine particles, fluorine resin fine particles, silica fine particles, calcium carbonate fine particles, alumina fine particles, tin oxide, and carbon black.

The coating layer containing the charge control agent in the present invention is formed by applying a coating liquid containing the charge control agent on at least one side of the polyester film and drying. At this time, the coating liquid may be a solvent type or an aqueous type, but an aqueous type is preferable for coating during the film forming process. A required amount of a surfactant such as an anionic surfactant, a cationic surfactant, or a nonionic surfactant can be added to the aqueous coating liquid. As such a surfactant, the surface tension of the aqueous coating liquid is 40 dy.
Ne / cm or less, which promotes wetting to the polyester film is preferable. For example, polyoxyethylene alkyl phenyl ether, polyoxyethylene
Fatty acid esters, sorbitan fatty acid esters, glycerin fatty acid esters, fatty acid metal soaps, alkyl sulfates,
Examples thereof include alkyl sulfonates, alkyl sulfosuccinates, quaternary ammonium chloride salts, and alkylamine hydrochlorides. Further, within the range not to lose the effect of the present invention, for example, ultraviolet absorbers, pigments, lubricants,
Other additives such as anti-blocking agents can be mixed.

The solid content of the coating solution is usually 30% by weight.
Or less, and more preferably 10% by weight or less.

The aqueous coating liquid is preferably applied to the polyester film before the completion of the crystal orientation. Here, the polyester film before the completion of the crystal orientation is an unstretched film obtained by melting a polymer to form 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, it includes 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 lateral direction to complete oriented crystallization). Of these, application to a uniaxially stretched film is preferred from the viewpoint of economy and cleanliness. That is, by applying the aqueous coating liquid in the polyester film forming process, it is advantageous in terms of quality and cost.

As a coating method, any known coating method can be applied. . For example, a roll coating method, a gravure coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be applied alone or in combination.

The polyester film to which the coating liquid has been applied and before the crystal orientation is completed is guided to processes such as drying, stretching and heat setting. For example, a vertically uniaxially stretched polyester film coated with an aqueous coating solution is guided to a stenter, dried, horizontally stretched, and thermally fixed. These processes can be performed by conventionally known means, conditions, and the like.

The amount of coating is preferably 20 g or less, more preferably 10 g or less, per 1 m ² of the running film. The thickness of the coating layer is preferably 0.005 to 2 μm, more preferably 0.01 to 0.4 μm, as a final thin film.

In the composite polyester film of the present invention, the amount of charge on the surface and the sign of the charge are controlled so as to be suitable for the use mode and application. Therefore, especially for magnetic tapes, magnetic disks, magnetic cards, graphic materials, photosensitive materials, etc. Useful as a base film.

[0030]

EXAMPLES The present invention will be described below more specifically with reference to examples. The film characteristics in the examples were measured by the following methods. 1. Amount of Charge and Its Sign The charge amount on the film surface (coated surface) and its sign are measured by an electrometer immediately before the film having a width of 510 mm and a length of 1000 m is run through a nip roll at a speed of 80 m / min and wound up.

Example 1 Isophthalic acid-terephthalic acid-5-Na sulfoisophthalic acid-neopentyl glycol-diethylene glycol copolymerized polyester (A-1) 65 wt%, sodium decane sulfonate (B-1) 12 wt%, charged system of formula I
Control agent (C-1) 10wt% and polyoxyethylene Jer Chin nonylphenyl ether concentration of the solid content of 4 consisting of 13 wt%
% Methyl ethyl ketone aqueous solution was prepared.

[0032]

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A polyethylene terephthalate having an intrinsic viscosity of 0.62 measured in orthochlorophenol at 25 ° C. is melt-extruded on a rotating cooling drum maintained at 22 ° C. to form an unstretched film, and the unstretched film is then moved in the machine axial direction. After stretching 3.4 times, the aqueous coating solution was applied to one surface of the film at a coating amount of 3 g / m ² (wet) by a kiss coating method. Subsequently, it is stretched 3.5 times in the horizontal direction, and further 235
A heat treatment was performed at ℃ to obtain a 17 μm thick composite biaxially oriented polyester film. Table 1 shows the charging characteristics of the composite polyester film.

In this example, A-1 was used as a binder in view of the adhesiveness, blocking resistance and recoverability of the magnetic paint, and B-1 was used as an antistatic agent in view of antistatic, moisture and heat resistance.
It is necessary to use -1, but in this case, the negative triboelectric charging on the film surface during running in the application process of the magnetic paint,
This is an example in which positive charge is controlled by using C-1. This control avoids trouble during the production of the magnetic tape for a computer.

Examples 2 to 8 and Comparative Examples 1 and 2 The same procedure as in Example 1 was carried out except that the composition of the aqueous liquid was changed. Table 1 shows the charging characteristics of the obtained composite polyester film. Table 1 also shows the adjustment targets for the positive and negative charges in each example.

Examples 4 to 8 are examples in which the charge generated in the rubber nip roll portion in the magnetic paint application step when used as a base film of an audio magnetic tape is controlled to be negative. In this case, A-3 and A-4 are used as binders for durability and solvent resistance, and B-3 and B are used as antistatic agents for antistatic properties at a relative humidity of 25%.
It is necessary to use −4. However, in this case, since the charge is positive, the charge is controlled to be negative by using C-2.

Comparative Example 3 The same procedure as in Example 1 was carried out except that the application of the aqueous liquid was omitted. Table 1 shows the charging characteristics of the obtained polyester film.

[0038]

[Table 1]

Note) Explanation of reference symbols A-2: Methyl methacrylate-Na acrylate-glycidyl methacrylate-acrylamide-β-hydroxyethyl acrylate copolymer (Tg = 53 ° C.). A-3: Polyethylene glycol (molecular weight 1500)-
Diphenylmethane diisocyanate-ethylene diamine-ethylene glycol-dimethylol ammonium propionate-based polyurethane (Tg = 0 ° C.) / Polyethylene glycol (molecular weight: 20,000) = 90/10. A-4: Polytetramethylene adipate (molecular weight: 200
0) -Tolylene diisocyanate-ethylene glycol-dimethylol ammonium propionate-based polyurethane (Tg = 5 ° C.) / Glycerin triglycidyl ether = 10/1. B-2: Potassium dodecylbenzenesulfonate. B-3: Ethyl methacrylate-acrylic acid-ethyl acrylate-β-hydroxyethyl acrylate-N-trimethylallylamine chloride copolymer (Tg = 42
° C). B-4: Methacrylamide-acrylic acid-glycidyl methacrylate-β-hydroxyethyl methacrylate-N
-Vinyl pyridine chloride copolymer (Tg = 53 ° C). C-2: a charge control agent of the following formula II.

[0040]

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[0041]

According to the present invention, it is possible to provide a composite polyester film which realizes a charging state suitable for the use of the film by adjusting the amount of charge on the film surface and the sign of the charge.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-255940 (JP, A) JP-A-61-144342 (JP, A) JP-A-61-2740 (JP, A) JP-A-4- 144734 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7/04

Claims (5)

(57) [Claims] 1. At least one side of a polyester film
Metal-containing azo compounds, metal compounds of salicylic acid derivatives and
At least one selected from compounds represented by the following structural formulas
A composite polyester film provided with a coating layer containing a charge control agent. Embedded image 2. The method according to claim 1, wherein the coating layer contains an antistatic agent.
The composite polyester film according to the above. 3. The composite polyester film according to claim 1, wherein the coating layer is formed by applying and drying an aqueous coating solution containing a charge control agent. 4. The composite polyester film according to claim 2, wherein the coating layer is formed by applying and drying an aqueous coating solution containing a charge control agent and an antistatic agent. 5. The coating layer formed by applying an aqueous coating solution to the polyester film before the crystal orientation is completed, drying the film, and then stretching and orienting the film. The composite polyester film according to the above.