JPH01146931A - Antistatic polyester film - Google Patents

Abstract

PURPOSE:To obtain a film excellent in antistatic property and stable even in application and drawing steps, by applying a coating solution containing a polymer having pyrrolidinium rings in the main chain to a polyester film and drawing this film. CONSTITUTION:This polyester film is formed by applying a coating solution containing a polymer having pyrrolidinium rings in the main chain to at least either of its surfaces and drawing this film. As the polyester of said polyester film, a polyethylene terephthalate containing at least 80mol% ethylene terephthalate units based on the entire structural units, or a polyethylene naphthalate containing at least 80mol% ethylene naphthalate units based on the structural units is used. Said polymer having pyrrolidinium rings in the main chain means a polymer based on a structure of formula I or II (wherein R1 and R2, which may be the same or different groups, are alkyl or phenyl groups which may have substituents).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyester film with excellent antistatic properties.

[Prior Art and Problems to be Solved by the Invention] Although biaxially oriented polyester films have excellent properties and are widely used, they have the disadvantage of being easily charged.

Antistatic methods include methods of kneading anionic compounds such as organic sulfonates and organic phosphates, methods of vapor depositing metal compounds, and methods of applying anionic compounds, cationic compounds, or so-called conductive particles. be.

Although the method of kneading anionic compounds can be manufactured at low cost, there is a limit to the antistatic effect, and since the compounds that can be used are low molecular weight compounds, the adhesiveness between the film and the laminated layer decreases due to blooming. However, there are problems such as lack of water resistance and transfer of compounds. The method of depositing a metal lid compound has excellent antistatic properties, and its use as a transparent conductive film has expanded in recent years, but the manufacturing cost is high and although it is suitable for specific applications, it is not suitable for general antistatic properties. It is difficult to use as a film. Although the method of coating conductive carbon or conductive metal particles has the advantage of having a relatively good antistatic effect and being relatively inexpensive to manufacture, it has the disadvantage that the transparency of the film deteriorates.

For this reason, a method of applying an anionic compound or a cationic compound as an antistatic agent is widely used as a method of preventing static electricity on biaxially oriented polyester.

As a method for producing a biaxially stretched polyester film having a coating layer, there is a method called a coating/stretching method (in-line coating method) in which a coating solution is applied, and then the film is stretched and heat treated.

Compared to the method of applying a coating solution to a biaxially stretched polyester film to form a coating layer, this method simultaneously forms the film and coats it, so wide products can be produced at a relatively low cost. Not only is the adhesion between the coated layer and the polyester film of the substrate good, the coated layer can be made thinner, but also the surface properties of the coated layer are characteristic.

However, the antistatic effect of coating and stretching may not be exhibited.

In addition, when the heat treatment conditions such as temperature and film residence time are relaxed, the volatilization and decomposition of the antistatic agent are suppressed and the antistatic effect is achieved, but the mechanical strength and dimensional stability of the film are unsatisfactory. In many cases, only one can obtain it.

[Failure to solve the problem]

In view of the above-mentioned problems, the present inventors conducted extensive studies and found that a polymer having a specific structure has excellent antistatic properties and is stable even during the coating and stretching process, leading to the completion of the present invention. .

That is, the gist of the present invention resides in an antistatic polyester film, which is formed by applying a coating liquid containing a polymer having a pyrrolidium ring in the main chain to at least one side and then stretching the film.

The polyester of the polyester film in the present invention is polyethylene terephthalate, which is ethylene terephthalate, or polyethylene naphthalate, which is ethylene naphthalate, based on the go molar relationship of its constituent units.

The polyester film of the present invention may contain inorganic particles, organic particles, organic lubricants, antistatic agents, stabilizers, dyes, pigments, and organic polymers as a composition, if necessary. In order to impart slipperiness to a polyester film, fine particles are included in the film composition, but the type, size, and composition of the protrusion-forming agent are determined depending on the required properties such as slipperiness and transparency of the product to be used. The amount is selected appropriately.

The polymer having a pyrrolidium ring in the main chain in the present invention is a polymer having a structure of the following formula (1) or (It) as a main component.

In the formula, R and IR2 are usually an alkyl group, a phenyl group, or the same group, or the alkyl group or phenyl group may be substituted with a group shown below.

Substitutable groups include, for example, hydroxy, amide, carbo-lower alkoxy, lower alkoxy, phenoxy, naphthoxy, cyanide, thio-lower alkoxy, thiophenoxy, cycloalkyl, tri(lower alkyl) ammonium, lower alkyl, and nitro group. only on alkyl groups,
Further, the halogen group can be substituted only on the phenyl group.

In addition, 1t1 and R2 may be chemically bonded,
For example, +CH2+ (m=--5 integer) CH(CHa
) CH(CH3)--CH=CH-CH=CH-,
-CH=CH-CH=N --CH=CH-N=CH- +CH2+ C)+cH2+ +CH2) a O(
Examples include CH2)2-. Further, only one of R1 and R2 may be hydrogen.

X- in the formula is ct-1Br-1%5024- or 1
Inorganic acid group of zPO34-, CH3So, -1C2H
5So,-1 The polymer of formula (1) in the present invention can be obtained by cyclopolymerization. Further, the polymer of formula (11) can be obtained by cyclopolymerizing the compound of formula (■) in a system using sulfur diacid as a solvent. Polymerization is
Using a polymerization initiator such as hydrogen peroxide, benzoyl peroxide, or tertiary butyl peroxide in a polar solvent such as water or methanol, ethanol, impropatol, formamide, dimethylformamide, dioxane, acetonitrile, or sulfur dioxide as a solvent. This can be carried out by any known method, but is not limited thereto.

The polymer having a pyrrolidium ring in the main chain in the present invention may contain a compound of formula (■) and a compound having a polymerizable carbon-carbon unsaturated bond as copolymerization components.

The molecular weight of the polymer having a pyrrolidium ring in the main chain in the present invention is preferably SOO to 1,000,000, more preferably 100θ to 50,000. When the molecular weight of this polymer is less than 200, although it has an antistatic effect,
The strength of the coating film was weak, and it was sticky and easily blocked. When the molecular weight of this polymer is higher than 1 million,
The viscosity of the coating liquid is high, and handling and coating properties tend to deteriorate.

As the polymer having a pyrrolidium ring in the main chain in the present invention, commercially available products from Dai-Kogyo Seiyaku Co., Ltd., Nittobo Co., Ltd., and Merck & Co., Ltd. can be used for this purpose, but the polymer is not limited to these.

The coating liquid in the present invention preferably has a polymer having a pyrrolidium ring in its main chain dissolved or dispersed in water. The medium of the coating liquid is preferably water, but in order to improve the agglomeration stability of the coating agent, base compounds, organic solvents such as N-methylpyrrolidone may be added to the coating liquid.

The coating liquid used in the present invention includes methylol- or alkylol-based urea-based, melamine-based, and guanamine-based crosslinking agents to improve the adhesion (blocking property), water resistance, solvent resistance, and mechanical strength of the coating layer. , acrylamide-based, polyamide-based compounds, epoxy compounds, aziridine compound block polyisocyanates, silane coupling agents, titanium coupling agents, zirco-aluminate coupling agents, heat-reactive, peroxide-based, photo-reactive vinyl compounds, etc. It may also contain a photosensitive resin or the like. In addition, silica, inorganic fine particles, and
Silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, titanium oxide,
It may contain barium salt, carbon black, molybdenum sulfide, antimony oxide sol, etc., and if necessary, antifoaming agents, coating improvers, thickeners, organic lubricants, etc.
It may contain organic polymer particles, antioxidants, ultraviolet absorbers, blowing agents, dyes, and the like. Furthermore, the coating solution of the present invention may contain a polymer other than the polymer of the present invention in order to improve the properties of the coating solution or the coating layer.

The above-mentioned coating liquid can be applied to a polyester film using a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or any of these described in "Coating Method" by Yuji Harasaki, Kishoten, published in 1997. A method of applying a coating solution on an unstretched polyester film using a coating device other than the above and biaxially stretching it sequentially or simultaneously, - applying it to an axially stretched polyester film and further stretching it in a direction perpendicular to the direction of the previous uniaxial stretching. Alternatively, there is a method in which a biaxially stretched polyester film is coated and further stretched in the transverse and/or longitudinal directions.

The above-mentioned stretching step is preferably carried out at 0 to 730°C, and the stretching ratio is at least 7 times or more in terms of area ratio, preferably 6 to 20 times.

The stretched film is heat treated at /30-2!717°C.

Furthermore, in the maximum temperature zone of the heat treatment and/or the cooling sawn at the heat treatment outlet, 0.2 to 20
% relaxation is preferred.

In particular, the coating solution is applied to a uniaxially stretched polyester film that has been stretched to 6 times the color by a roll stretching method at O~/30'C, and the coating solution is dried appropriately, or the polyester-axially stretched film is immediately coated without drying. A preferred method is to stretch the film 2 to 6 times at 80 to 130°C in a direction perpendicular to the previous stretching direction, and heat treat it at 730 to 250°C for 7 to 400 seconds.

According to this method, it is possible to dry the coating layer at the same time as stretching, and the thickness of the coating layer can be reduced according to the stretching ratio, and a film suitable as a polyester film base material can be produced at a relatively low cost. can.

The coating liquid in the present invention may be applied to only one side of the polyester film, or may be applied to both sides. When the polyester film of the present invention is coated only on one side, a coating layer other than the coating liquid of the present invention can be formed on the opposite side as necessary to impart other properties to the polyester film of the present invention.

In order to improve the applicability and adhesion of the coating agent to the film, the film may be subjected to chemical treatment or discharge treatment before coating. Further, in order to improve the adhesion, coating properties, etc. of the biaxially stretched polyester film of the present invention to the coating layer, the coating layer may be subjected to a discharge treatment after the coating layer is formed.

The polyester film coated with the coating solution of the present invention obtained as described above preferably has a thickness in the range of 3 to 0θμ, and the thickness of the coating layer is in the range of (LO/μ to 0θμ). Sμ is preferably in the range of 0.02μ to 1μ.If the thickness of the coating layer is less than 0.0/β, it is difficult to obtain a uniform coating layer, which tends to cause uneven coating on the product. If the film is thick, it is not preferable because the lubricity decreases and the film becomes difficult to handle.

〔Example〕

The present invention will be described below with reference to examples, but the present invention is not limited by the following examples unless it exceeds the gist thereof.

In addition, the evaluation method in the example is based on the method described below.

(1) Charge decay property: Using a Statinku Honest Meter (trade name) manufactured by Shishido Shosha Co., Ltd., in an atmosphere of 1.23°C and 130% RH, the discharge electrode was placed at a height of 2 cm above the sample.
A voltage of OKV is applied to charge the film, and discharging is stopped after the amount of charge is saturated. Thereafter, the charge decay property of the sample is measured with an electrometer placed 2 cm above the sample, and the half-life is used as a standard for evaluation.

Less than S seconds: Extremely good 9-30 seconds: Good 30-00 seconds: Fairly good 600 seconds or more: defective Further, 33'c was added to the sample charged by the above method.

Blow 100% RH air for 7 seconds (forced humidification method)
. Evaluate whether any charge remains using the strong humidification method.

(2) Surface resistivity: Yokogawa/Heuret/F Nocard's inner electrode! rO-diameter, outer electrode 7om diameter same as above.
A circular electrode (boogAc trade name) was heated at 23°C, Sθ
The sample was placed in an atmosphere of %RH, a voltage of 700μ was applied, and the surface resistivity of the sample was measured using the company's high resistance meter /1329A (product name). I made a judgment.

/θ9Ω/B or less: Extremely good 109 to 1011Ω/Port: Good 101' to /θ13Ω/Port: Fairly good 1013Ω/B or more: Poor Comparative example/2g of polyethylene terephthalate with an intrinsic viscosity of 0.6
The mixture was melt-extruded at a temperature of 0°C to 300°C and cast on a cooling drum using an electrostatic adhesion method to obtain an amorphous film with a thickness of g-〇μ.

This film was stretched 3.3 times in the machine direction at 9 °C, further stretched 3.3 times in the cross direction at 770 °C, and heat-treated at 210 °C to form a biaxially stretched polyester film with a thickness of 75μ. 1-6 The charge attenuation property of this film was poor, and was also poor even by the forced humidification method. The surface resistivity of this film is 701
5 to 101,607 units were defective.

Example 1 A coating solution containing Jarol DC-902P (trade name) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., which is a polymer shown in formula (1), was applied to one side of Comparative Example / after longitudinal stretching and before transverse stretching. Thereafter, polyester films having coating layers of various coating thicknesses were obtained in the same manner as in Comparative Example. The relationship between the thickness of the coating layer and the antistatic property of this film was as follows.

That is, the polyester film of the present invention was useful as an antistatic film.

Example PAS manufactured by Nittobo Co., Ltd., which is a polymer shown in formula (II)
-gg (trade name) was coated in the same manner as in Example/1 to obtain a film having a coating thickness of o, o y sμ and a polyester film as a base having a thickness of 73μ.

The charge decay properties and surface resistivity of this film were extremely good.

That is, the polyester film of the present invention was useful as an antistatic film.

Example 3 Jarol DC-902P (trade name) used in Example/
Coating liquid (A) containing 70 parts (solid content and below), 30 parts of polyvinyl alcohol with a saponification degree of g g % and a polymerization degree of g00, 3 parts of Jarol DC-902P, and the above-mentioned portion of polyvinyl alcohol. Blended coating liquid (B)
were applied in the same manner as in Example 1 to a coating thickness of 0. θy-
A film of sμ and a base polyester film 'tsa was obtained.

The charge attenuation property and surface resistivity of this film are as follows:
) was very good, and that using coating liquid CB) was good.

That is, the polyester film of the present invention was useful as an antistatic film.

Example 1 Intrinsic viscosity 0265 containing titanium oxide as additive particles
Polyethylene terephthalate was melt-extruded at a temperature of 2gO to 3θθ°C and cast onto a cooling drum using an electrostatic adhesion method to obtain an amorphous film with a thickness of qO of 5μ. This film was stretched 3.5 times in the machine direction at 95°C, and a polymer of the formula
Jarol DC-, 103P (product name) 3 manufactured by Industrial Seiyaku Co., Ltd.
A coating solution containing 5 parts of the polyvinyl alcohol getter part used in Example 3 was applied, further stretched 3.3 times in the transverse direction, and heat treated at 210°C, resulting in a coating thickness of 0.011! ;n,
A base polyester film having a thickness of 33 μm was obtained.

The charge decay properties and surface resistivity of this film were extremely good.

That is, the polyester film of the present invention was useful as an antistatic film.

〔Effect of the invention〕

As described above, the coating agent containing a polymer having a pyrrolidium ring in the main chain of the present invention described in detail has excellent charging properties and heat resistance, and can easily produce an antistatic polyester film without any problems during the coating and stretching process. It can be done and its industrial value is high.

Claims (1)

[Claims] (1) An antistatic polyester film, which is formed by applying a coating liquid containing a polymer having a pyrrolidium ring in the main chain to at least one side and then stretching the film.