KR20040086334A - Applied Film - Google Patents

Abstract

In a polyester film having a coating layer on one side, the surface resistivity of the surface of the coating layer is 1 × 10 ¹³ Ω or less, and after the film is heat-treated at 180 ° C. for 30 minutes, the amount of polyester oligomer on the surface of the coating layer is heat-treated. The coating film which is 8 times or less of the amount of polyester oligomers before performing the process. Such an applied film has excellent antistatic performance, prevents adhesion of dust and the like, and has few optical defects.

Description

Coating film {Applied Film}

The biaxially stretched polyester film has excellent mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance, transparency, and the like, and is widely used including a base film, a plate making film, a packaging film, and an optical film of a magnetic recording medium. It is used for a purpose.

However, as a common problem with plastic films, there is a drawback that static electricity is generated and easily charged, thereby causing problems such as poor runability of the film or the processed product, adhesion of dust and the like to the surroundings.

Generally, as an antistatic method of a polyester film, a method of incorporating a compound having a low molecular weight anionic surfactant type such as an organic sulfonate, a method of depositing a metal compound, an anionic compound and a cationic compound, or a so-called conductive compound The method of apply | coating to a surface is mentioned.

The method of incorporating an anionic compound has advantages in that it can be manufactured at low cost, but there is a limit in the antistatic effect. In addition, since a low molecular weight compound is used, the anionic compound gathers on the surface of the polyester film by so-called blooming, the adhesive force between the polyester film and the top coat layer is lowered, and the anionic compound is electrodeposited on the film and the conveying roll. Problem occurs. This also lowers the durability of the antistatic performance.

Although the method of depositing a metal compound is excellent in antistatic property and the use expands as a transparent conductive film in recent years, although manufacturing cost is high and it is seeking for a specific use, it is difficult to use as a general antistatic film.

The method of coating conductive compounds such as conductive carbon has the advantage that the antistatic effect is relatively good and the production can be made relatively cheap, while the transparency of the film is deteriorated.

For this reason, the method of apply | coating a high molecular weight anionic compound and a high molecular weight cationic compound to a film as an antistatic agent is widely employ | adopted as an antistatic method of a polyester film.

As a manufacturing method of the biaxially-stretched polyester film which has an application layer, the method of apply | coating especially in a film manufacturing process is widely performed from the viewpoint of economy and the characteristic. Typical examples include a method of applying after longitudinal stretching and transverse stretching, and transverse stretching and heat fixing.

In addition, in recent years, as the use of polyester films is diversified, the processing and use conditions of the films are also diversified. For example, when the polyester film is left at a high temperature of 100 ° C. or higher, oligomers leaching out from the inside on the film surface precipitate. Therefore, various problems arise in processing or using a film under such conditions.

Conventionally, as a method of preventing the precipitation of oligomers, reduction of the oligomer contained in the raw material by solid phase polymerization and improvement of the hydrolysis resistance of the polyester film by using a terminal blocker have been performed. Under more stringent conditions, there is a problem such that the precipitation prevention of the oligomer cannot be satisfied to a sufficient degree, and the manufacturing cost is too high.

Moreover, although various coating films are proposed for the purpose of surface modification of a polyester film as mentioned above, the problem which accelerates precipitation of an oligomer arises depending on the composition to apply | coat.

This invention is made | formed in view of the said situation, The subject solved is to provide the polyester film which has the outstanding antistatic performance, the adhesion of dust etc. is prevented, and there are few optical defects.

The present invention relates to a coating film having good antistatic performance, preventing adhesion of dust and the like, and less optical defects.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining the said subject, the present inventors discovered that the said subject was solved by providing the coating layer of a specific structure, and came to complete this invention.

That is, the gist of the present invention is a polyester film having a coating layer on one side, wherein the surface resistivity of the surface of the coating layer is 1 × 10 ¹³ Ω or less, and the coating layer after heat-treating the film at 180 ° C. for 30 minutes. The amount of the polyester oligomer on the surface is 8 times or less than the amount of the polyester oligomer before performing the heat treatment, in the coated film.

Hereinafter, the present invention will be described in detail.

"Polyester" which comprises the polyester film of this invention is polyester obtained by polycondensation of a dicarboxylic acid component and a glycol component. These dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalene dicarboxylic acid, adipic acid, sebacic acid, 4,4'-diphenyldicarboxylic acid, 1,4-cyclohexyldicarboxylic acid, and the like. Examples of the glycol component include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, and the like.

Typical polyesters used in the present invention include polyethylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimentylene terephthalate, and the like. One polyester may be sufficient, and the other component and additive may be included as needed.

In order to facilitate handling, the polyester film of the present invention may contain particles for the purpose of imparting diactivation. Particles used for this purpose include inorganic particles such as silica, calcium carbonate, magnesium carbonate, calcium phosphate, kaolin, talc, aluminum oxide, titanium oxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide, and the like. , Organic particles such as crosslinked polymer particles, calcium oxalate, and precipitated particles in the polyester production step can be used.

Although the particle diameter and content of the particle | grains to be used are selected according to the use and the objective of a film, about an average particle diameter, it is normally 0.005-5.0 micrometers, Preferably it is the range of 0.01-3.0 micrometers. When the average particle diameter exceeds 5.0 µm, the surface roughness of the film becomes too rough, and particles easily fall off from the film surface. If the average particle diameter is less than 0.005 µm, the surface roughness may be too small and sufficient diactivation may not be obtained. About particle content, it is 0.001-30.0 weight% normally with respect to polyester, Preferably it is 0.01-10.0 weight%. When the amount of particles is large, the mechanical properties and transparency of the film tend to be impaired, and when the amount is small, the activity tends to be poor.

Moreover, you may add an additive other than the said particle as needed. Such additives include, for example, antistatic agents, stabilizers, lubricants, crosslinkers, antiblocking agents, antioxidants, dyes, pigments, sunscreens, ultraviolet absorbers and the like.

In the present invention, the polyester film may have a multilayer structure as long as the requirements of the present invention are satisfied, and in the case of the multilayer structure, a layer other than polyester may be included. In addition, even if it is provided only in the single side | surface of a film, or even if it is provided in both surfaces, it is naturally included in the concept of this invention, and at least the coating layer should just satisfy | fill the requirements of this invention.

The polyester film of the present invention is a coating film having a surface resistivity of 1 x 10 ¹³ Ω or less on the surface of the coating layer, preferably a surface resistivity of 1 x 10 ¹² Ω or less, more preferably 1 x 10 ¹⁰ Ω or less. If the surface resistivity exceeds 1 x 10 ¹³ Ω, problems such as adhesion between films and poor processing, adhesion of foreign matter and dust when unwinding the rolled-up film and sequentially conveying the stacked single-layered film Cause

Moreover, in the polyester film of this invention, after heat-processing a film at 180 degreeC for 30 minutes, the amount of polyester oligomers on the surface of an application layer is 8 times or less of the value before copper processing, and after heat-processing a film at 180 degreeC for 30 minutes It is preferable that the amount of polyester oligomer of the application layer surface is 3.0 mg / m <^2> or less.

When the amount of the polyester oligomer on the surface of the coating layer after the heat treatment exceeds these ranges, the use of the polyester film may be limited. For example, when an adhesive layer is provided to a polyester film provided with a release layer, and after being bonded to another member, when used as a release film for removing a polyester film and a release layer, an oligomer precipitated from the film is The problem which crystallizes in an adhesion layer and becomes optical coupling, such as a bright spot, is known. In addition, in the case of the transparent film, the appearance is damaged by the haze up, and in the case of using and providing the top coat layer, the adhesiveness with the top coat layer may be reduced, or the processing equipment may be contaminated to reduce the productivity. do.

In order to solve the various problems as described above, the present invention is to provide a coating layer exhibiting the ability to lower the surface resistivity of the polyester film, and to prevent precipitation of the oligomer. In the present invention, as the components constituting the coating layer provided on the film, a compound having a quaternary ammonium base and a polyvinyl alcohol are preferably used. The term 'compound having a quaternary ammonium base' refers to the main chain and the side chain in the molecule. It has a component comprising a quaternary ammonium base. As such a component, for example, a pyrrolidinium ring, a quaternized alkylamine, copolymerized with acrylic acid and methacrylic acid, a quaternized N-alkylaminoacrylamide, vinylbenzyltrimethylammonium salt, 2- Hydroxy 3-methacryloxypropyl trimethylammonium salt etc. are mentioned. In addition, these may be combined or copolymerized with another resin. Moreover, as an anion used as a counter ion of these quaternary ammonium salts, there exist ions, such as halogen, alkyl sulfate, alkyl sulfonate, nitric acid, for example. Moreover, in this invention, it is preferable that the compound which has quaternary ammonium base is a high molecular compound. If the molecular weight is too low, it is easily removed from the coating layer, causing performance deterioration with time, and the coating layer may stick. Moreover, when molecular weight is low, heat stability may be bad. In order not to cause such a problem, it is preferable that the number average molecular weight of the compound which has quaternary ammonium base is normally 1000 or more, More preferably, it is 2000 or more, Especially preferably, it is 5000 or more. On the other hand, if the molecular weight is too high, the compound may cause a problem such as that the viscosity of the coating liquid becomes too high. In order not to cause such a problem, it is preferable that a number average molecular weight is 500,000 or less.

The polyvinyl alcohol used in the present invention can be synthesized by a general polymerization reaction and is preferably water-soluble.

Although the polymerization degree of polyvinyl alcohol is not specifically limited, Usually, 100 or more, Preferably the thing of 300-30000 is used. When the degree of polymerization is less than 100, the water resistance of the coating layer tends to be lowered. Although the saponification degree of polyvinyl alcohol is not specifically limited, Polyvinyl acetate saponification which is 70 mol% or more normally, Preferably it is 80 mol% or more and 99.9 mol% or less is actually used.

Moreover, in the application layer, 1 type, or 2 or more types of water-soluble or dispersible binder resin of that excepting the above can be used together as needed. As said binder resin, polyester, polyurethane, acrylic resin, vinyl resin, for example. Epoxy resins, amide resins, and the like. Each of these skeletal structures may have a composite structure substantially by copolymerization or the like. Examples of the binder resin having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, vinyl resin graft polyurethane, and the like.

Moreover, the crosslinking reactive compound may be included as needed. The crosslinking reactive compound mainly crosslinks with a functional group contained in the coating layer constituent, and is preferable because it can improve the cohesion, surface hardness, scratch resistance, solvent resistance, and water resistance of the coating layer.

The coating layer of the film of this invention may contain additives, such as surfactant, an antifoamer, a coating property improving agent, a thickener, an antistatic agent, an organic type lubricant, organic particle | grains, an inorganic particle, antioxidant, a ultraviolet absorber, a foaming agent, a dye, and a pigment. These additives may be used independently and may use 2 or more types together as needed.

The proportion of the compound having a quaternary ammonium base contained in the coating layer constituents is usually 10 to 99% by weight, preferably 20 to 95% by weight. If the ratio is too high or too low in these ranges, the desired antistatic performance and oligomer precipitation prevention performance may not be obtained.

It is preferable that the coating liquid used in the present invention is an aqueous solution or an aqueous dispersion in terms of handling, working environment, or the like, and the organic solvent may be contained as long as the medium mainly contains water and does not depart from the gist of the present invention.

Although there is no restriction | limiting in particular in solid content concentration of a coating liquid, Usually, it is 0.3-65 weight%, Preferably it is 0.5-30 weight%, More preferably, it is 1-20 weight%. Even when the concentration is too high and too low in these ranges, it is difficult to provide an application layer having a thickness necessary to fully exhibit the function.

The thickness of the coating layer is a dry thickness, and usually 0.003-1.5 탆, preferably 0.005-0.5 탆, more preferably 0.01-0.3 탆. When the thickness of an application layer is less than 0.003 micrometer, there exists a possibility that sufficient performance may not be obtained, and when it exceeds 1.5 micrometer, blocking of films will be easy to occur.

As a method of providing a coating layer to a polyester film, the method of apply | coating a coating liquid in the process of manufacturing a polyester film is used suitably. For example, the method of extending | stretching after apply | coating to an unstretched film, the method of extending | stretching after apply | coating to a uniaxial stretched film, the method of extending | stretching after apply | coating to a biaxially stretched film, etc. are mentioned. In particular, after apply | coating a coating liquid to an unstretched or uniaxial stretched film, the method of simultaneously drying and extending | stretching in a tenter is economical.

As a method of apply | coating a coating liquid to a polyester film, the coating technique as shown by Harasaki Yukio Co., Shin-Shoten, the "1979 coating method" can be used, for example. Specifically, the air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnated coater, reverse roll coater, transfer roll coater, gravure coater, kiwi roll coater, cast coater, spray coater, curtain coater, calendar coater, Techniques such as extrusion coaters, bar coaters and the like.

Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to a following example, unless the summary is exceeded. In addition, the evaluation method and the processing method of a sample in an Example and a comparative example are as follows.

(1) Surface resistivity:

Using a high resistance measuring instrument (HP4339B) and a measuring electrode (HP16008B) manufactured by Hewlett-Packard, Japan, after sufficiently humidifying the sample in a measuring atmosphere at 23 ° C. and 50% RH, the surface resistivity of the coating layer after 1 minute at an applied voltage of 100 V. Was measured.

(2) Heat treatment method of film:

A4 size kent paper and heat treated polyester film were overlaid. At that time, four corners were fixed with a gem clip or the like so that the surface on which the oligomer amount was measured was on the outside, and the kent paper and the polyester film were fixed. The polyester film is left to heat for 30 minutes in an oven at 180 ° C. under a nitrogen atmosphere.

(3) Film surface oligomer amount measuring method:

The polyester film was folded and the square box was made so that the upper part might open and the area of the base side might be 250 cm <^2> . When providing an application layer, an application layer surface shall be inward.

Then, 10 ml of DMF (dimethylformamide) is placed in a box prepared by the above method, and left for 3 minutes to recover DMF. The recovered DMF was supplied to liquid chromatography (島 津 LC-7A) to obtain the oligomer amount of the polyester in the DMF, and the value of this oligomer was divided by the film area in which the DMF was contacted (mg / m ^2). ).

(4) Film surface oligomer amount evaluation 1:

The film which was not heat-treated and the film which heat-processed the film at 180 degreeC for 30 minutes are prepared by the method shown in said (2). Next, in the method shown in said (3), the amount of both film surface oligomers is measured, respectively, and the value after heat processing is divided and the ratio is calculated | required.

(5) Film surface oligomer amount evaluation 2:

The film is heat-treated at 180 ° C. for 30 minutes by the method shown in (2) above. Then, the oligomer amount on the surface of the film is measured by the method shown in (3) above.

(6) Dust adhesion evaluation (ash test):

After sufficient humidity control of a polyester film in 23 degreeC and 50% RH measurement atmosphere, a coating layer is reciprocated 10 times with a cotton cloth. It was quietly put on the finely pulverized tobacco ash, and the adhesion state of the ash was evaluated based on the following criteria.

(Circle): There is no adhesion even if a film makes contact with ash.

(Triangle | delta): The film was made to contact with ashes, and less adhered.

X: A large amount adheres only to the film close to the ash.

(7) optical defect inspection:

On the surface of the polyester film (the surface to which the coating layer was provided in the following example and a comparative example), the release layer shown to the following (R-1) was provided so that application amount might be set to 0.1 g / m <^2> (after drying), and it will release. A film was obtained. Then, an acrylic pressure-sensitive adhesive was applied on the release layer and dried at 180 ° C. for 5 minutes to provide an adhesive layer having a thickness of 20 μm. The adhesive layer sample obtained by adhering this to a glass plate and removing a release film was placed on the stage of a polarizing microscope, and set the polarizer which sandwiched the sample so that it might become cross nicol, and observed optical abnormal defects, such as a bright point. The optical defect counted only the thing of 0.5 micrometer or more in size, and converted the number per area of the adhesion layer, and evaluated the following references | standards.

(Circle): An optical defect is less than 0.5 piece / m <^2> (it does not become a problem in actual use).

(Triangle | delta): Optical defect is 0.5 piece / m <^2> or more and less than 1.0 piece / m <^2> (it becomes a problem in actual use).

X: Optical defect is 1.0 piece / m <^2> or more (it becomes a problem in actual use).

<Release layer (R-1) composition>

A curable silicone resin / curing catalyst / solvent in a weight ratio of 100/5/2000, except that the solvent is a mixture of toluene / MEK in a weight ratio of 1/1.

Comparative Example 1

Polyethylene terephthalate chip having an intrinsic viscosity of 0.65 was sufficiently dried, heated and melted at 280 to 300 ° C., extruded from a T-shaped slit into a sheet, and subjected to a mirror cooling drum having a surface temperature of 40 to 50 ° C. using an electrostatic adhesion method. It cooled and solidified closely and produced the unstretched polyethylene terephthalate film. The film was stretched 3.7 times in the longitudinal direction while passing through a 85 ° C. heating roll group to obtain a monoaxially oriented film. This uniaxial oriented film was extended | stretched 4.0 times in the width direction at 100 degreeC by the tenter stretching machine, and heat-processed at 230 degreeC again, and obtained the biaxially-oriented oriented polyethylene terephthalate film of 50 micrometers in film thickness.

Example 1

In the middle of a film manufacturing process, application | coating and drying of the film were performed. Specifically, in the manufacturing process of the film by the same procedure as the comparative example 1, the coating liquid was apply | coated to the single side | surface of the uniaxial oriented film after longitudinal stretch or before lateral stretch as shown to the following (A). It was then dried using heat in a tenter-drawing machine. The following was carried out similarly to the comparative example 1, and obtained the laminated biaxially stretched oriented polyethylene terephthalate film which provided the coating layer of 0.05 g / m <^2> on the 50-micrometer-thick base film.

<Coating liquid (A)>

Cherol DC-303P manufactured by Cheil Industries Co., Ltd., a polymer having a pyrrolidinium ring in the main chain, and a polyvinyl alcohol / silica sol having an average particle diameter of 0.05 μm in terms of solid content in terms of weight composition of 8 / Aqueous coating liquid containing in ratio of 5/10/5.

EXAMPLES 2-4

In Example 1, the amount of 0.05 g / m ² was applied on the base film having a thickness of 50 µm in the same manner except that the contents of the coating liquid were changed to the following (B), (C) and (D) The laminated biaxially stretched oriented polyethylene terephthalate film which provided the layer was obtained, and it was set as Example 2, Example 3, and Example 4, respectively.

<Coating liquid (B)>

Cherol Industrial Co., Ltd. Cherol DC-303P / saponification degree = 88 mol%, polymerization degree = 500 polyvinyl alcohol / methoxymethylol melamine of the polymer which has a pyrrolidinium ring in a principal chain, the bacterium made by Dainippon ink chemical industry An aqueous coating liquid containing a silica sol having an average particle diameter of 0.05 μm in a ratio of 40/20/35/5 in terms of weight composition in terms of solid content.

<Coating liquid (C)>

Polyvinyl methyl / ethyl methacrylate quaternized / saponification degree = 88 mol%, polymerization degree = 500 polyvinyl alcohol / methoxymethylol melamine, benzamine / silica particles of average particle diameter 0.05㎛ An aqueous coating liquid contained in the ratio of 40/20/35/5 by the weight composition ratio of solid content conversion.

<Coating liquid (D)>

In a usual manner, compound (D-1) obtained by copolymerizing trimethylaminoethyl methacrylate quaternized substance / methyl methacrylate in a ratio of 65/35 by weight composition ratio. Using this compound D-1, D-Chem, a polyvinyl alcohol / methoxymethylol melamine having a degree of polymerization of 88% by mole and a degree of polymerization of 500, has a vaccumamine and a silica sol having an average particle diameter of 0.05 µm. Aqueous coating liquid containing in the ratio of 70/10/15/5 by the weight composition ratio of solid content conversion.

[Comparative Examples 2 and 3]

In Example 1, a coating layer in an amount of 0.05 g / m ² was provided on a base film having a thickness of 50 μm in the same manner except that the contents of the coating liquid were changed to the following (E) and (F). A laminated biaxially oriented polyethylene terephthalate film was obtained, and Comparative Examples 2 and 3 were obtained, respectively.

<Coating liquid (E)>

Baccarmine made from Dainippon Ink and Chemicals Co., Ltd., a polyvinyl alcohol / methoxymethylol melamine having a degree of saponification of 88 mol% and a polymerization degree of 500, and a silica sol having an average particle diameter of 0.05 µm in terms of weight composition in terms of solids content 85/10/5 Aqueous coating liquid containing in the ratio of.

<Coating liquid (F)>

Nippon Carbide Nicarzol / Methoxymethylolmelamine produced by copolymerization of polytrimethylaminoethyl methacrylate quaternary / acrylic acid alkyl ester with methacrylic acid alkyl ester. An aqueous coating liquid containing a baccarmine / 0.05 µm silica sol manufactured by ink chemical industry in a ratio of 40/20/35/5 in terms of weight composition in terms of solid content.

The characteristics and practical properties of the film thus obtained are shown in Tables 1 and 2 below.

Table 1

Dust adhesion evaluation Optical defect inspection Example 1 ○ ○ Example 2 ○ ○ Example 3 ○ ○ Example 4 ○ ○ Comparative Example 1 X X Comparative Example 2 X △ Comparative Example 3 ○ X

TABLE 2

Surface resistivity (Ω) Oligomer amount evaluation 1 Oligomer amount evaluation 2 (mg / m ² ) Example 1 2 X 10 ⁹ 1.2 0.6 Example 2 1 X 10 ¹⁰ 1.4 0.7 Example 3 3 X 10 ¹¹ 1.2 0.6 Example 4 2 X 10 ¹¹ 2.4 1.2 Comparative Example 1 5 X 10 ¹⁴ 21 10.5 Comparative Example 2 5 X 10 ¹⁴ 8.2 4.1 Comparative Example 3 4 X 10 ¹¹ 22.4 11.2

Industrial Applicability According to the present invention, it is possible to provide a coating film with less optical defects, which prevents contamination by static electricity and does not cause problems due to precipitation of oligomers even after use at high temperatures.

Claims (7)

In a polyester film having a coating layer on one side, the surface resistivity of the surface of the coating layer is 1 × 10 ¹³ Ω or less, and after the film is heat-treated at 180 ° C. for 30 minutes, the amount of polyester oligomer on the surface of the coating layer is heat-treated. It is 8 times or less of the amount of polyester oligomers before performing the coating film characterized by the above-mentioned. The coating film of Claim 1 whose amount of polyester oligomers on the surface of a coating layer after heat-processing a film for 30 minutes at 180 degreeC is 3.0 mg / m <^2> or less. The coated film according to claim 1 or 2, wherein the coating layer contains a compound having a quaternary ammonium moiety. The coated film according to claim 3, wherein the compound having a quaternary ammonium base is a high molecular compound. The coating film according to any one of claims 1 to 4, wherein the coating layer contains polyvinyl alcohol. The coating film according to any one of claims 1 to 5, wherein the coating layer is dried and stretched after applying the aqueous coating liquid to the film. The coated film according to any one of claims 3 to 6, wherein the proportion of the compound having a quaternary ammonium base in the coating layer constituent is in the range of 10 to 99% by weight.