KR20050117289A - High antistatic polyester film - Google Patents

Abstract

The present invention relates to a coating film having excellent transparency, adhesion, heat resistance, and antistatic properties by preparing a polymer type antistatic coating composition, the technical configuration of which isophorone diisocyanate as an isocyanate component, terephthalic acid as a polyol component, and isophthalic acid. To 100 parts by weight of a polyester polyol composed of ethylene glycol and diethylene glycol, and 2,2-dimethylolpropyl ionic acid as a chain extender, and hexamethoxymethyl melamine 10 to 50 as a melamine type crosslinking agent. Part and 20 to 1000 parts of bis (2-chloroethyl) ether-1,3-bis [3- (dimethylamino) propyl] urea copolymer as a cationic polymer type antistatic agent, and the total solid content weight percentage is 0.2 to 20 An excellent antistatic polyester comprising coating a phosphorus mixed water dispersion coating composition on a polyester film The present invention relates to a le film, and the present invention provides an excellent polyester film without adhesion of foreign matter and dust because the present invention has good transparency and excellent antistatic property by applying a coating method using a urea copolymer type antistatic agent containing a cationic nitrogen atom. It is very suitable as an antistatic film.

Description

High antistatic polyester film {High antistatic polyester film}

The present invention relates to a polyester coating film having excellent antistatic properties, in particular by producing an antistatic coating composition containing a polymer type antistatic agent, a polyester coating film having excellent antistatic properties, transparency, adhesion and heat resistance It is about.

In general, polyester film has excellent mechanical properties, and has excellent properties such as heat resistance, transparency, and chemical resistance, so that many uses for photography, drafting, overhead projector (OHP), electrical and electronic parts, general industry, packaging, etc. It is used in the field. However, such a polyester film has a disadvantage that the surface resistivity is large and is easily charged by friction or the like. When the polyester film is charged, impurities or dust adheres to the surface of the film, and discharge occurs in the film manufacturing process and the processing process. Therefore, when the organic solvent is used in these processes, there is a high risk of ignition and electrical and electronic parts. When used as a material of the material, since it causes static damage, it is essential to give the antistatic performance when using these.

Conventionally, methods for preventing the antistatic of such films include internal addition methods using anionic compounds such as organic sulfonates and organic phosphates, methods of depositing metal compounds, methods of applying conductive inorganic particles, low molecular type anionics or cations. The method of apply | coating a sexual compound etc. is known.

Internal addition methods using anionic compounds such as organic sulfonates and organic phosphates have the advantages of low cost, change over time or stability, but the disadvantages that hinder the inherent properties of the film support, the limitation of antistatic effect, and blooming. There is a problem such as deterioration of adhesion of the film lamination site due to, and the method of depositing a metal compound is excellent in antistatic properties and recently used a lot for conductive film applications, but the manufacturing cost is too high, it is used only for specific applications. In addition, the coating method using a low molecular type anionic or cationic compound has a relatively good antistatic effect and is advantageous in terms of manufacturing cost, and is widely applied. However, after a certain time, a part of the antistatic agent moves to the interface and accumulates. In most cases, the initial performance is good, but there is a disadvantage in that the antistatic effect is drastically deteriorated with the passage of time.

Accordingly, the present invention provides a method for coating on a film support, to provide an antistatic water dispersion coating solution of the mixed composition in order to solve the above-mentioned problems, by using the coating on the film during the stretching process or stretch heat-setting using In particular, it aims at providing the polyester film excellent in antistatic property, transparency, adhesiveness, and heat resistance.

The present invention for achieving the above object is an isophorone diisocyanate as an isocyanate component, a polyester polyol composed of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol as a polyol component, 2,2-dimethylolpropylionic acid as a chain extender Bis (2-chloroalkyl) represented by Structural Formula (1) using a water-dispersible urethane-based resin (A) containing mainly as a binder, a hexamethoxy methyl melamine as a melamine crosslinking agent, and a cationic antistatic agent It provides an antistatic aqueous dispersion composition of a mixed composition which is an ether-1,3-bis [3- (dimethylamino) alkyl] urea copolymer, wherein the inorganic particles having a surfactant and antistatic properties, for example, a middle layer ( layered silicate mineral "Laponite" (from Rockwood Additives, Co., UK), "Kunipia" or "Water vein" (Sumecton) "(made by Kunimine Industries, Co., Japan), etc., is applied to the film during the stretching process, or stretched and heat-fixed, so that the antistatic, transparency, adhesiveness and heat resistance are particularly excellent. It is characterized by providing a polyester coating film.

     Structural Formula (1)

In the above structural formula, R ₁ is an alkyl group having 1 to 4 carbon atoms,

R ₂ , R ₃ is preferably an alkyl group having 1 to 8 carbon atoms,

             X is a halogen atom such as Cl, Br, I, dialkyl halide ether,

CH ₃ OSO ₃ and C ₂ H ₅ OSO ₃ and the like are preferred.

In the present invention, it is preferable that the mixing ratio (A) :( B) of the mixed water dispersion coating composition is 1: 0.2 to 1:10 in solid content weight ratio, more preferably 1: 0.5 to 1: 5.

If the ratio of the antistatic agent is too low, it is difficult to achieve sufficient surface resistance, and if the ratio of the antistatic agent is too high, the viscosity of the aqueous dispersion becomes high, resulting in a decrease in coating properties, and sufficient durability and solvent resistance cannot be obtained. do.

The solid content concentration of the water-dispersible coating composition used is not particularly limited, but is usually 30% by weight or less, preferably 0.2 to 20% by weight, more preferably 0.5 to 15% by weight, particularly preferably 1 to 10% by weight. Range. When the solid content concentration of the coating composition is lowered, there is a problem in uniformity of the coating surface, such as application repulsion, and when the solid content concentration of the coating composition exceeds 30% by weight, the viscosity of the coating liquid is increased, thereby deteriorating the appearance of the coating.

In addition, examples of the polymer type antistatic agent other than the urea copolymer type antistatic agent described above include polyvinyl benzyl type, poly (meth) acrylate type styrene- (meth) acrylate copolymer type, styrene-maleimide copolymer type, and methacrylate. Cationic or anionic antistatic agents, such as methacrylimide copolymer types, are known, but these high molecular compounds have drawbacks such as transparency, antistatic properties and durability.

The polymeric antistatic agent of this invention has a weight average molecular weight of 1000-500,000. In the case where the weight average molecular weight is 1000 or less, the molecular weight thereof is so small that the film forming ability is lowered, and the polymer may be decomposed by the high temperature applied in the stretching step of the polyester film. In addition, when the weight average molecular weight is 500,000 or more, the self-viscosity of the antistatic copolymer is too high, resulting in poor operability and coating property due to excessive increase in viscosity during the preparation of the dispersion, emulsion or solution of the copolymer. Therefore, preferable weight average molecular weights are 3000-100,000, Most preferably, it is 3000-30,000.

The cationic polymer type antistatic agent of this invention obtained by this shows the outstanding antistatic property. The reason for this property is not clear, but the amine unit incorporated in the aminoalkylurea copolymer of the present invention retains moisture contained in the air, and thus, X is ionized to impart electrical conductivity, thereby lowering electrical resistance. Can be.

The plastic base film used as the coating base of the present invention is not particularly limited, and any known one conventionally known as a base film of an antistatic coating can be used. In the present invention, a polyester resin such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and the like will be described mainly with respect to polyethylene terephthalate, but the base of the antistatic coating composition of the present invention is limited to a polyester sheet or a film. It doesn't work. The polyester which comprises the said film refers to the polyester obtained by polycondensing aromatic dicarboxylic acid and aliphatic glycol.

Examples of the aromatic dicarboxylic acid include terephthalic acid, 2,6-naphthalenedicarboxylic acid, and the like, and aliphatic glycols include ethylene glycol, diethylene glycol and 1,4-cyclohexanedimethanol. Representative polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like.

The polyester may be a copolymer containing a third component. Examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (for example, P-oxybenzoic acid). Ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1, 4- cyclohexane dimethanol, neopentyl glycol, etc. are mentioned. In addition, these dicarboxylic acid components and glycol components can use 2 or more types together.

In view of its handleability in the present invention, it is preferable to contain particles in the film under conditions that do not impair transparency. In this case, the particles to be added include inorganic or organic particles such as silica, talc, calcium carbonate, alumina, silica alumina, titanium oxide, zeolite, polystyrene, silicon dioxide, calcium carbonate, titanium dioxide, lithium fluoride, barium sulfate, carbon black and the like. In addition, these particles may use 2 or more types together.

The amount of particles is preferably small in terms of transparency, and the amount of particles also depends on the size of the particles. The average particle diameter of the particles is usually 0.02 to 2 µm, more preferably 0.05 to 1.5 µm. The amount of the addition is preferably a ratio of 5000 ppm or less, more preferably 3000 ppm or less. An additive, a UV absorber, a stabilizer, or a pigment can be added here within the range which does not affect the intrinsic property of a polymer.

As a method of containing particle | grains in a film, a well-known method can be used.

For example, the particles may be added at any stage of the polyester manufacturing process. In particular, after the step of esterification or the end of the transesterification reaction, the polycondensation reaction is preferably carried out by adding as a slurry dispersed in ethylene glycol or the like before the start of the polycondensation reaction.

In the production of the film, the sheet melted and extruded in the extrusion port according to the extrusion method is stretched and oriented in the biaxial directions such as the longitudinal and transverse directions.

In the extrusion method, the polyester is melted and extruded in an extrusion port, cooled and solidified by a cooling roll to obtain an unstretched sheet. In this case, in order to improve the planarity of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and electrostatically applied adhesion or liquid coating adhesion is preferably used. In the electrostatic application bonding method, a linear electrode is generally provided on the upper surface side of the sheet in a direction that is directly parallel to the flow of the sheet, and a static voltage is applied to the sheet by applying a DC voltage of about 5 to 10 kW to the electrode to give the sheet and the drum. Improves adhesiveness with In addition, the liquid coating adhesion method is a method of improving the adhesion between the drum and the sheet by uniformly applying the liquid to all or part of the surface of the rotary cooling drum (only the portion in contact with both ends of the sheet). In this invention, it is preferable to use the electrostatic application close_contact | adherence method.

The biaxial stretching orientation of the film is not particularly limited, but a simultaneous biaxial stretching method, a sequential biaxial stretching method, and the like are used. In the simultaneous biaxial stretching method, the unstretched sheet is usually stretched and oriented in the machine direction and the width direction at a temperature adjusted at 70 to 120 ° C., preferably 80 to 110 ° C., and the draw ratio is the area ratio. Usually 4 to 50 times, preferably 7 to 35 times, more preferably 10 to 20 times. Subsequently, heat treatment is then carried out in a state of tension at a temperature of usually 170 to 250 ° C. or in a relaxed state of 30% or less to obtain a stretched alignment film. In the sequential biaxial stretching method, the unstretched sheet is stretched in one direction by a stretching machine of a roll or tenter method. The stretching temperature is usually 70 to 120 ° C, preferably 80 to 110 ° C, and the draw ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Then, the film is drawn in a direction perpendicular to the drawing direction of step 1. The stretching temperature is usually 70 to 120 ° C, preferably 80 to 115 ° C, and the draw ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. Subsequently, heat treatment is carried out at a temperature of 170 to 250 ° C. under tension or in a relaxation state of less than 30% to obtain a stretched alignment film.

In the stretching, a method in which one-way stretching is performed in two or more stages can be used. In this case, it is preferable that the draw ratios in the two directions finally fall within the above ranges. Moreover, you may extend | stretch to longitudinal and / or horizontal direction again before heat processing or after heat processing as needed.

The thickness of the polyester film is usually 5 to 250 µm, preferably 10 to 188 µm. The method of coating on the polyester film support is mainly a resin binder, an antistatic agent and a mixture composed of other additives 1) a method of applying the antistatic treatment by stretching during the fixing in the manufacturing process of the film support and 2) film support There is a method of applying an antistatic composition after stretching and heat fixing.

As the method proposed so far, the methods of 1) and 2) are applicable. In particular, it is preferable to use a binder for improving the adhesion between the antistatic coating composition and the polyester film. Applicable binders include acrylic resins, ester resins, urethane resins, epoxy compounds, styrene resins, cellulose compounds, vinyl resins and derivatives thereof, and may contain thermoplastic resins or thermosetting resins.

In the present invention, as a crosslinking agent used to improve the durability of the applied antistatic layer, methylolated or alkoxymethylated melamine compounds, urea compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, oxazoline compounds, It is preferable to contain at least 1 sort (s) chosen from a silane coupling agent type compound.

In the aqueous dispersion composition of the present invention, a surfactant can be used to improve the coating properties of the substrate. Preferred surfactants are nonionic surfactants and cationic surfactants. Anionic surfactants are undesirable because they can form ionic bonds with cationic polymeric antistatic agents. The amount of the surfactant used is generally not more than 25% by weight, preferably not more than 20% by weight, based on 100% by weight of the polymeric antistatic agent.

In addition, in order to impart stable antistatic properties, inorganic particles having antistatic properties may be used in combination within 30% by weight of the total coated solid content.

Examples of the inorganic particles may include layered silicate minerals, and two or more kinds may be used in combination. In this case, the layered silicate minerals to be used include natural and synthetic compounds, and typically include one or more minerals selected from the group of Smectite or Montmorillonite.

Non-limiting examples of synthetic minerals or synthetic phyllosilicates include the layered silicate minerals "Laponite" (manufactured by Rockwood Additives, Co., UK), "megatite" and "fluorohectorite". , Kunimine Industries, Co. of Japan "Kunipia" and "Sumecton" manufactured by Ltd. may be included, and among these, "laponite" and "kunipia" are preferred.

The film coating layer of the present invention is preferably formed by applying an aqueous coating liquid (water-soluble resin or water-dispersible resin containing water as a medium), but may be formed by applying an aqueous coating liquid containing a small amount of an organic solvent. In this case, examples of the organic solvent include alcohols such as ethanol, isopropanol, ethylene glycol and glycerin, ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomer methyl ether and tetrahydrofuran, acetone and methyl ethyl. Ketones, such as a ketone, Ester, such as ethyl acetate, Amine, such as dimethylethanolamine, etc. can be illustrated. These can be used individually or in combination of two or more, and can improve the stability, coating property, and coating-film characteristic of a coating liquid by making an aqueous coating liquid select and contain these organic solvents suitably as needed.

As a method of applying the primer composition, a coating method such as gravure roll or reverse gravure roll, a coating method using a mayer bar, an application method using an air knife, and The same general method may be used, and it is preferable to perform corona discharge treatment before coating to improve the coating property of the composition by introducing polar groups and increasing the surface tension to improve the adhesion between the composition and the polyester resin. Do.

Polyester film according to the present invention has the advantage of having excellent antistatic properties, transparency, adhesiveness, heat resistance.

Hereinafter, the binder resin in the coating composition used in the examples is isophorone diisocyanate as the isocyanate component, polyester polyol composed of terphthalic acid, isophthalic acid, ethylene glycol and diethylene glycol as the polyol component, and 2,2 as the chain extender. Water-dispersed urethane resin (A) mainly containing dimethylolpropyl ionic acid was used, and as crosslinking agent, hexamethoxymethyl melamine as melamine crosslinking agent, and cationic bis (2-chloroethyl) ether-1 as antistatic agent, 3-bis [3- (dimethylamino) propyl] urea copolymer was used.

The antistatic polyester film of the present invention as described above is described in more detail by Examples and Comparative Examples, but the present invention is not limited to these Examples. Evaluation of physical properties of the antistatic polyester film prepared in Examples and Comparative Examples was measured by the following evaluation method.

<Evaluation Method>

(1) surface resistance

After leaving the measurement sample for 8 hours under the condition of 25 ° C. × 55 RH%, the antistatic property was evaluated with a surface resistance measuring instrument (“ADVANTEST”, manufactured by Advantest Japan), and the unit was Ω / square.

(2) Haze

A polyester film sampled at 10 cm x 10 cm was placed vertically on a haze measuring instrument ("Automatic digital hazemeter" manufactured by Nippon Densoku Co., Ltd., Japan), and a wavelength of 400 to 700 nm was placed in the perpendicular direction of the sample placed vertically. The value shown by transmitting light having it was measured. At this time, the haze value is calculated by the following equation and displayed on the haze meter.

      HAZE (%) = (1 DF / TT) * 100

              DF: amount of scattered light

              TT: total transmittance of light

(3) heat resistance

After heat-treated the film applied in the hot air dryer for 10 minutes at 230 ℃,

The surface resistance is measured to determine the degree of difference with the surface resistance before heat treatment.

○: 1 × 10 ¹ Ω / square or less (excellent)

△: 1 × 10 ¹ Ω / square over 1 × 10 ² Ω / square or less (usually)

×: 1 × 10 ² Ω / square exceeded (bad)

(4) coating uniformity

     The appearance of the coated film was visually observed to determine the degree of uniform coating.

              ○: uniform coating

              X: coating state is uneven

(5) lacquer adhesion

      An oil-based lacquer for evaluation, consisting of 10 parts of n-butanol, 250 parts of methyl cellosolve, 10 parts of methyl ethyl ketone, 25 parts of cellulose acetate butyrate, and 3 parts of rhodamine ratio (dye), was coated on the coated film sample. After apply | coating at (# 18), and fully drying in 105 degreeC for 1 minute in a dryer, after drawing 100 graduations on the surface using a cross cutter, it peels off by sticking an adhesive tape. In this case, the evaluation was performed based on the number of remaining scales which did not peel out of 100 scales.

      Example: 100: No peeling off (excellent)

               0: All peeled off (defect)

(6) bifunctional

In accordance with ASTM-D 1894, a load was applied 200 g using a "Slippery Meter" manufactured by Dongyang Tester Co., Ltd., and the static activity and dynamic friction (μk) coefficient of the coated surface were measured to evaluate this activity.

Hereinafter, the present invention will be described in detail by Examples and Comparative Examples.

Example 1

Surfactant and polymer type antistatic agent bis (2-chloroethyl) ether-1,3-bis [3- (dimethylamino) propyl] urea copolymer were added to the pure water which passed the ion exchange resin, and after stirring well, A water-dispersed urethane resin and a melamine crosslinking agent are added and re-stirred to prepare a coating solution. The mixture was composed of 100 parts of urethane-based resin, 100 parts of antistatic agent, 10 parts of melamine-based crosslinking agent (hexamethoxymethylmelamine), and 2.5 parts of polyoxyethylene nonylphenyl ether (manufactured by Nippon Oil Holding Co., Ltd.) as a surfactant. Prepared.

[Production and Coating Method of Polyester Film Substrate]

Polyethylene terephthalate pellets having an intrinsic viscosity of 0.62 dl / g containing 60 ppm of porous amorphous spherical silica particles having an average particle diameter of 3.7 μm were sufficiently dried at 160 ° C. for 7 hours using a vacuum dryer, melted, and cooled through an extrusion die. It was contacted by the electrostatic application method to give an amorphous non-stretched sheet, which was heated again and stretched 3.5 times in the direction of film progress at 100 ℃. Next, after the corona discharge treatment on the surface of the film to be applied, the coating solution was applied using the Mayer bar coating method. The film was stretched 3.5 times in the direction perpendicular to the traveling direction of the film in a 105 to 140 ° C. tenter section, and then heat-treated at 240 ° C. for 4 seconds to obtain a 25 μm thick film. The evaluation result of the obtained film is shown in Table 1.

Example 2

100 parts of the urethane resin, 200 parts of bis (2-chloroethyl) ether-1,3-bis [3- (dimethylamino) propyl] urea, 10 parts of melamine crosslinking agent (hexamethoxymethylmelamine), and surfactant 2.5 It carried out by the same method as Example 1 except having used the mixed water dispersion composition of 3.125 weight% of total solids as a part. The evaluation results are shown in Table 1.

Comparative Example 1

In the same manner as in Example 1, except that 100 parts of the urethane-based resin, 10 parts of the melamine-based crosslinking agent (hexamethoxymethylmelamine), and 2.5 parts of the surfactant were prepared and used as a mixed aqueous dispersion composition comprising 1.125% by weight of a total solid. Was carried out. The evaluation results are shown in Table 1.

Comparative Example 2

100 parts of the urethane-based resin, 100 parts of polydiaryldimethylammonium chloride (made by Rhodia Co.), 10 parts of melamine-based crosslinking agent (hexamethoxymethylmelamine), and 2.5 parts of a surfactant, and a mixed aqueous dispersion composition comprising 2.5 parts by weight of a total solid. It carried out by the same method as Example 1 except having manufactured and used.

The evaluation results are shown in Table 1.

Comparative Example 3

100 parts of the urethane-based resin, 100 parts of sulfonate polystyrene (manufactured by National Starch), 10 parts of melamine-based crosslinking agent (hexamethoxymethylmelamine), and 2.5 parts of a surfactant, and a mixed aqueous dispersion coating composition comprising 2.125% by weight of total solids It carried out by the method similar to Example 1 except having manufactured and used. The evaluation results are shown in Table 1.

[Comparative Example 4]

100 parts of the urethane-based resin, 200 parts of quaternary ammonium salt (manufactured by Nippon Kayaku Co., Ltd.), 10 parts of melamine-based crosslinking agent (hexamethoxymethylmelamine), and 2.5 parts of surfactant were prepared, and a mixed aqueous dispersion composition was prepared. It carried out by the same method as Example 1 except having used and using. The evaluation results are shown in Table 1.

TABLE 1

Surface resistance Haze Heat resistance Coating uniformity Lacquer adhesion Activity ㎲ μk Example 1 10 ⁸ 1.35 ○ ○ 100 0.40 0.37 Example 2 10 ⁷ 1.72 ○ ○ 100 0.38 0.33 Comparative Example 1 10 ¹⁶ 1.15 ○ ○ 100 0.51 0.43 Comparative Example 2 10 ¹⁴ 1.57 △ ○ 100 0.55 0.41 Comparative Example 3 10 ¹¹ 1.48 △ ○ 100 0.57 0.41 Comparative Example 4 10 ¹⁰ 1.62 × ○ 80 0.43 0.34

As described above, according to the present invention, by applying a coating method using a urea copolymer type antistatic agent containing a cationic nitrogen atom, it has good transparency, and has excellent adhesiveness without adhesion of foreign matter or dust, and heat resistance. Providing this excellent polyester film is particularly suitable as an antistatic film for articles requiring transparency.

Claims (2)

Dispersed urethane resin mainly comprising isophorone diisocyanate as isocyanate component, polyester polyol composed of terephthalic acid, isophthalic acid, ethylene glycol and diethylene glycol as polyol component, and 2,2-dimethylolpropylionic acid as chain extender 100 -500 parts, 10-50 parts of hexamethoxymethylmelamine as a melamine type crosslinking agent, and bis (2-chloroethyl) ether-1,3-bis [3- (dimethylamino) propyl] urea as a cationic polymer type antistatic agent A polyester film having excellent antistatic properties, comprising a mixed water dispersion coating composition composed of 20 to 1000 parts of a mixture, and having a total solid weight% of 0.2 to 20 on a polyester film. The polyester film having excellent antistatic properties according to claim 1, wherein the mixed water dispersion coating composition is made by adding a particulate antistatic agent, a surfactant, and organic or inorganic particles.