KR0130660B1 - Polyester film - Google Patents

Abstract

1 or 25wt% titanium dioxide of rutile crystal with average particle-diameter 0.1 or 3um a characterizing agent of 0.01 or 1.0 wt%; fluorescent organic pigment of 0.05 or 0.3 wt%; and a 2:1 mixture of aluminum cobalt compound and manganic compound of 0.01 or 1.0 wt% as an inorganic pigment.

Description

Polyester film

The present invention relates to a polyester film, and in particular, it has excellent printing properties, antistatic properties and mechanical properties of the film surface, good white opacity and suppresses phenomena as much as possible, in particular, various prepaid cards, labels, photo paper, printing A polyester film suitable for use in materials, industrial substrates, and the like.

Generally, prepaid magnetic cards such as communication cards such as telephone cards, credit cards such as bank cards, flat cards such as department store cards, and transportation cards such as subway cards are mainly made of polyvinyl chloride and paper. come. However, polyvinyl chloride has a disadvantage in that its use is limited due to environmental pollution, and the film is easily deformed due to heat generated during printing or use, and in the case of paper, water resistance, mechanical strength and durability are weak. We have, and there are many difficulties to actually use. Due to these problems, recently, the use of polyester films based on polyester having excellent mechanical properties and easy portability as basic raw materials is gradually increasing.

Polyester, especially polyethylene terephthalate (hereinafter referred to as PET) is chemically and physically stable, has high mechanical strength, and has excellent electrical properties such as heat resistance, chemical resistance, mechanical properties and processability, as well as electrical insulation. It is widely used in industrial fields for magnetic recording media, condensers, photographic films, labels, packaging materials, as well as various molded articles.

Many studies have been conducted for using polyester films having high transparency and surface gloss for applications such as magnetic cards. Recently, in order to control the high transparency of a polyester film, a white polyester film using an inorganic compound filler having a high refractive index, a brightener for enhancing whiteness, and the like has been evaluated as the most suitable for this use.

However, such a white polyester film for magnetic cards is easily discolored (yellowing) when exposed to high temperature or sunlight for a long time, it is not suitable for high quality cards. In addition, due to the characteristics of the polyester film, static electricity is easily generated and accumulated, resulting in problems such as uneven printing and poor adhesion of the ink in the printing process, and the most fatal phenomenon may cause loss of various information stored on the magnetic card. There are many difficulties in using it widely. In addition, agglomeration of additives and clogging of the film-forming filter generated during the polymerization input production process are becoming obstacles to productivity improvement and mass production. In particular, when a large amount of inorganic material is directly added in the polymerization process, quality problems such as bubble generation and discoloration occur, and yellowing phenomenon is severe due to the generation of by-products and an increase in residence time. In general, it is a fact that it is difficult to add more than 10% of the inorganic substances in the polymerization process.

Various methods have been developed to solve various problems as described above while utilizing the excellent properties of the polyester film. Japanese Patent Application Laid-Open Nos. 62-243120 and 2-206622 disclose methods for adding inorganic particles to polyester, and Japanese Patent Laid-Open No. 2-185332 discloses using barium acid alone. In Korean Patent No. 3-50241, a mixture of pulley olefin resins with polyester was added, followed by stretching by mixing barium sulfate and calcium carbonate. However, among the inorganic compounds used to control the refractive index, calcium carbonate causes eye fatigue by excessively increasing the glossiness of the film surface, and barium sulfate makes the concealability not only higher than the titanium compound but also makes it appear blue. Due to the disadvantage of falling luxury, there are many difficulties in industrial application. In addition, the results of these studies not only suggest the applicability of inorganic materials but also do not mention the methods to solve various problems in the process.

In view of the above problems of the polyester film, the present invention aims to provide a white polyester film which has increased opacity and imparted antistatic properties and easy adhesion to ink on the surface of the film.

In the polyester film of the present invention for achieving the above object, in the polyester film of 60% by weight or more of the film constituent components of the ethylene terephthalate, titanium dioxide of rutile crystals having an average particle diameter of 0.1 to 3㎛ It is characterized by containing 0.01 to 1.0% by weight, 0.01 to 1.0% by weight of the antistatic agent, 0.05 to 0.3% by weight of fluorescent organic pigment, and a 2: 1 mixture of an aluminum cobalt compound and a manganese compound as an inorganic pigment.

In particular, the antistatic agent is preferably a sulfonic acid metal salt derivative having an acid value of 1.0 mgKOH / g or less, and a fluorescent organic pigment is preferably a bisbenzoazole-based compound having light emission characteristics in the short wavelength region of visible light, and inorganic. It is preferred that the pigments are bluish CoAl ₂ O ₃ and violet NH ₄ MnP ₂ O ₇ .

In the present invention, a titanium film of rutile crystals having excellent dispersibility and light resistance is used as a filler in a polyester film to improve whiteness and concealment, and to add a fluorescent organic pigment to increase the short wavelength reflectance of visible light, and aluminum cobalt compound and manganese compound. The inorganic pigment of 2: 1 is added to remove light blue light and color light with titanium dioxide, and antistatic property and ink adhesion property can be imparted to the film surface by using antistatic agent. .

Hereinafter, the present invention will be described in more detail.

The polyester in this invention is obtained by polycondensing the acid component which has aromatic dicarboxylic acid as a main component, and the glycol component which has alkylene glycol as a main component. Examples of the aromatic dicarboxylic acid include dimethyl terephthalic acid, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, cyclohexane, dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyldicarboxylic acid and diphenyl ether. Dicarboxylic acid, anthracene dicarboxylic acid, α, β-bis (2-chlorophenoxy) ethane-4, 4′-dicarboxylic acid and the like, among which dimethyl terephthalic acid and terephthalic acid are particularly preferable. The alkylene glycols include, for example, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethyl glycol, hexamethylene glycol, hexylene glycol, and the like, of which ethylene glycol is particularly preferable.

The polyester of the present invention is a homopolyester of 60% by weight or more of PET and may be copolymerized within the remaining 40% by weight. Copolymer components include, for example, diol compounds such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene glycol, 1, 4-cyclohexane dimethanol, 5-sodium sulforesorcin, adipic acid, 5-natralium sulfoisophthalic acid and the like include dicarboxylic acid components and polyfunctional carboxylic acid components such as trimellitic acid and pyromellitic acid.

The polyester of the present invention preferably has an intrinsic viscosity measured at a concentration of 0.3 g per 25 ml of orthochlorophenol at 35C in the range of 0.4 to 0.9 d1 / g, and particularly preferably in the range of 0.5 to 0.8 d1 / g. . If the film is made of polyester having an intrinsic viscosity of less than 0.4 dl / g, breakage occurs frequently during stretching, which greatly lowers the productivity, and lowers mechanical properties such as mechanical strength in the final film. In addition, when the intrinsic viscosity exceeds 0.9d1 / g, since the melt viscosity is very high, difficulties in the manufacturing process, such as extrusion instability occurs, it is also undesirable because the productivity in the post-process is greatly reduced.

In the present invention, 1 to 25% by weight of titanium dioxide rutile crystals having an average particle diameter of 0.1 to 3 µm, 0.01 to 1.0% by weight of antistatic agent, 0.05 to 0.3% by weight of fluorescent organic pigment and inorganic pigment As an example, a mixture of an aluminum cobalt compound and a manganese compound in a ratio of 2: 1 is added to 0.01 to 1.0% by weight to prepare a white polyester film particularly suitable for magnetic cards. Hereinafter, look at each of these additives in detail.

Generally used titanium dioxide is classified into rutile form and anatase form depending on crystal structure. Titanium dioxide with anatase crystal structure, which is a cubic system, has high water adsorption property and causes cohesion in compounding process, thereby degrading the optical properties of the film surface, and is easily deteriorated when exposed to the external environment, especially temperature, sunlight and moisture. On the other hand, the rutile crystal, which is a hexagonal system, effectively absorbs harmful ultraviolet rays and converts its energy into a form of heat, thereby preventing the organic polymer from being deteriorated by ultraviolet rays. In order to improve the concealability by using the titanium dioxide of the rutile crystals as a filler of the polyester, the light scattering effect should be maximized. Light scattering is influenced by the inorganic spacing and the average size. If the particles are too large or the spacing is too small, the diffraction hardly occurs. If the particles are too small, light does not recognize the inorganic particles and just passes through them. Therefore, the titanium dioxide used in the present invention is slightly smaller than 1/2 of the wavelength of light to be scattered, and the one having 0/1 to 3.0 µm is used.

Whiteness of the film is preferably about 80 to 110%, preferably 85 to 105% level. If the whiteness is lower than 80%, the film has a color rendering machine, resulting in a luxurious feeling when printing, and if it is higher than 110%, there is a hearing device on the surface of the film. In addition, the light transmittance of the film is preferably 0.5 to 2.0%, preferably about 0.6 to 1.0%. Since the light transmittance of the film is higher than 2.0% and the concealability of the film is lowered, it is not good to see the back side, and to be lower than 0.5%, the strength of the film is weakened because it must contain a large amount of microbubbles. The amount of titanium dioxide added may vary depending on the thickness and use of the polyester film, but adds 1 to 25% by weight of polyester. If the amount of titanium dioxide is more than 25% by weight, the mechanical properties of the film, such as the strength, flexibility, etc. of the film is lowered, and the whiteness and the light transmittance are almost constant due to the increased amount of the film, so that the effect of the large amount cannot be obtained.

As the antistatic agent added to the polyester film of the present invention, a sulfonic acid metal salt derivative having an acid value of 1.0 mgKOH / g or less represented by the following formula is preferable, and the resistance of the film surface is added by adding 0.1 to 1.0% by weight of the polyester. 10 ¹² Ω or less.

R-SO ₃ M

(Here, R is an alkyl group having 8 to 25 carbon atoms, and M is an alkaline earth metal or alkali metal including Li, Na, K, Mg, etc.)

When the amount of the antistatic agent is less than 0.01% by weight, the antistatic property is hardly given. When the amount of the antistatic agent is more than 1.0% by weight, fine fisheye is formed on the surface of the film, so that the physical properties of the film are greatly reduced, and poly Degradation of the ester occurs to significantly reduce the mechanical properties and whiteness of the film. Such compounds include, for example, sulfonic acid metal salts such as potassium octylbenzenesulfonate, potassium nonylbenzene sulfonate or potassium undecylbenzenesulfonate, and one or mixtures thereof may be used, but is not limited thereto. no. Since these sulfonic acid metal salt derivatives have excellent heat resistance and excellent compatibility with polyester, when the film is added to polyester to produce a film, the antistatic property of the film is increased and the surface tension is increased. Have When the surface tension of the film is 45 dyne / cm or more, the adhesion to the ink and various coating liquids is excellent, and when smaller than this, the adhesion is not improved.

In addition, 0.05 to 0.3% by weight of a fluorescent organic pigment is added to the polyester film of the present invention, and 0.02 to 1.0% by weight of an aluminum cobalt compound and a manganese compound are added as an inorganic pigment to add a chromaticity of the film surface. Adjust Fluorescent organic pigments are preferably a bisbenzoa sulfate system. By absorbing light energy in the ultraviolet region and dissipating energy to the short wavelength region of visible light, the visible light short wavelength reflectance becomes low when only inorganic materials are injected. Improve. It is appropriate that the reflectance at 440 nm, which is the short wavelength region of visible light, is 75% or more, and is added at 0.05 to 0.30% by weight of polyester. When the amount of the pigment added is less than 0.05% by weight, the increase in reflectance at 440 nm hardly occurs, and when the amount of the penetration is more than 0.30% by weight, the reflectance at 440 nm becomes too high, resulting in a white-blue film, which adversely affects the film.

Titanium dioxide of the rutile crystal added to the present invention has better dispersibility and light resistance than anatase crystal structure, but there is a problem that the sharpness after printing is lowered due to the emitted blue light (Co1-b value increase), thereby improving it. Inorganic pigments need to be used. For the purpose of removing yellowish light, for example, an aluminum cobalt compound of CoAl ₂ O ₃ having a blue hexagonal crystal structure and a manganese compound of NH ₄ MnP ₂ O ₇ having a monoclinic crystal structure of violet are used. : 1 to 1.0% by weight in total. If the input amount is less than 0.01% by weight, there is no improvement effect of removing the yellow color. If the amount is more than 1.0% by weight, the color becomes yellow. In the present invention, by using an inorganic pigment, the same optical properties and whiteness can be obtained even with a small amount of an organic fluorescent pigment.

In the polyester film of the present invention, titanium dioxide of rutile crystals having excellent dispersibility and light resistance is added to improve concealment and opacity, and the addition of fluorescent organic pigments causes light divergence in a short wavelength region to provide a more beautiful appearance. The pigments were added together to remove the yellowish color, and the antistatic agent was included to improve the printability and handleability, and to be used in the kind and amount that can maximize the interaction effect between these additives.

In the present invention, in the polyester, in addition to the above-mentioned ash ash tartan, antistatic agent, fluorescent organic pigment and inorganic pigment, known additives such as UV absorbers, heat stabilizers, polycondensation catalysts, dispersants, and electrostatic applications A crystallization accelerator, a nucleating agent, an antilocking agent and the like may be added within a range not impairing the effects of the present invention.

As the method of adding the additives as described above, both of the following methods are possible. The first is a method in which each additive is slurried with ethylene glycol to the required concentration in the final film to be added directly during esterification or transesterification or polycondensation, which is advantageous for mass production. Second, the master batch chip prepared by preparing a polyester polycondensate in which all or part of the additives are added at high performance, and then mixed with a polyester polycondensate in which no additives or some additives are added in the extrusion process. As a batch chip manufacturing method, it is easy to adjust the concentration of the additive according to the degree of dilution of the master batch chip, which has the advantage of being suitable for small quantity multi-variation of the film. In order to maximize the dispersing effect of the additives of the present invention, after the primary compounding of the polyester master chip having 60 to 80% by weight by the improved compounding manufacturing technology, the film is mixed with the existing general chip secondary mixing In order to obtain a better dispersing effect and to prevent yellowing, compounding process conditions are most important.

The production method of the polyester film of the present invention is not particularly limited, and the polyester containing the above additive is melt-extruded by a tie-die method, an inflation method, or the like to obtain an unstretched sheet having an intrinsic viscosity of 0.4 to 0.9d1 / g. After making, it is at least uniaxially stretched and fixed to produce the polyester film of the present invention. The film thus obtained can be designed with an appropriate thickness according to the use, and if necessary, all kinds of surface treatments such as corona discharge treatment, coating of other resins, lamination and coextrusion may be performed on the film surface.

The present invention will be described in more detail with reference to the following examples. However, the following examples are only examples of the present invention and the present invention is not limited thereto.

Various performance evaluation on the film and process produced in the Example and comparative example of this invention were performed with the following measuring method.

(How to measure)

(1) glossiness

ASTM D523 (Standard Diameter: Color-coating Diameter, Measurement Angle: 60 Degrees)

(2) light transmittance

ASTM Dl003 (Diameter: 25mm, Scattering Angle: 2.5 °)

(3) 440 nm reflectance

The reflectance at 440 nm of visible light wavelength was measured using the light source color difference meter (Japan Color Corporation, Model: SZS-∑ 80).

(4) Co1-L, b value

JIS-L-1015

(5) dispersibility

When a resin was discharged at a speed of 30 kg using a pilot extruder, a change in filter pressure (ΔP) applied to a 350 mesh filter after a predetermined time was measured and compared.

(6) light resistance

Color-b value was measured using the light source color difference meter (Japan Electric Industry Co., Ltd., Model: SZS-∑ 80) after exposure to ultraviolet-ray for 30 hours on 60 degreeC conditions. The smaller the Color-b value, the better the light resistance.

(7) Antistatic characteristics (surface resistivity)

The surface resistance (unit Ω) was measured at 23 ° C., RH: 50%, and applied voltage: 500V using an insulation resistance measuring device of the US Hewlett.

(Example 1)

Dimethyl terephthalate and ethylene glycol are mixed in a 1: 2 equivalent ratio, a transesterification catalyst is added to produce a bis-2-hydroxyethyl terephthalate, a polyethylene terephthalate monomer, and a polycondensation reaction is performed by adding a conventional polycondensation catalyst. This completes the polymer with an intrinsic viscosity of 0.620 d1 / g. 60 parts by weight of rutile crystal titanium dioxide with an average particle diameter of 0.4 μm, 0.45 parts by weight of potassium octylbenzenesulfonate, 0.30 part by weight of a fluorescent whitening agent of a bisbenzoazole system, and CoAl ₂ O ₃ 0.12 based on 100 parts by weight of polyester. After preparing the highly dynamic master chip to which parts by weight and 0.04 parts by weight of NH ₄ MnP ₂ O ₇ were added, respectively, under the condition of compounder Screwrpm350 and temperature of 285 ° C, the mixture was diluted with a mixture ratio of 2: 1 and a general chip without additives, and then poly After drying, melting, and extruding the sheet to form a sheet by an ester film production method, the longitudinal draw ratio and the transverse draw ratio are each stretched 3.5 times to obtain a biaxially stretched polyester film having a thickness of 188 µm.

The film thus produced was tested according to the above measurement method, and as shown in the following [Table], glossiness 45%, light transmittance 0.8%, 440 nm reflectance 88%, Co1-L value 90%, Co1-b value 0.1% was excellent in physical properties, light resistance, dispersibility, antistatic properties.

(Example 2-8)

It carried out by the same method as Example 1, but carried out by changing the final content of the additive as shown in [Table], measured in the physical properties of the film produced is shown in [Table].

(Comparative Example 1-10)

It carried out by the same method as Example 1, was carried out by changing the final content of the additives as shown in [Table], and measured in the physical properties of the produced film is shown in the [Table].

As can be seen from [Table], from 1 to 25% by weight of titanium dioxide with rutile crystals having an average particle diameter of 0.1 to 3 µm and octylbenzenesulfonate as a sulfonic acid metal salt derivative having an acid value of 1.0 mgKOH / g or less, in the polyester film, 1.0% by weight, the fluorescent organic pigment is used as 0.05 to 0.3% by weight and the inorganic pigment CoA1 ₂ O ₃ and NHMnP ₂ O ₇ 2: a film prepared by the ratio was added 0.01 to 1.0% by weight of the mixture to a 1 glossiness, It was found that the light transmittance, the reflectance, the C-L and b values were excellent in physical properties, the surface resistivity was sufficiently low, and the dispersibility and light resistance were also good.

On the other hand, Comparative Example 1 using titanium dioxide of anatase crystals was particularly poor in dispersibility and light resistance, and Col-b value was poor in Comparative Examples 2 to 4, in which the use and ratio of inorganic pigments were not appropriate. In Comparative Examples 5 and 8, where the particle size of titanium dioxide was less than 0.1 µm or the usage amount was less than 1 wt%, the gloss was particularly high, and the particle size of titanium dioxide was larger than 3 µm or the usage amount was more than 25 wt% In Examples 6 and 7, in particular, dispersibility and surface resistivity were poor. In addition, in the case of Comparative Examples 9 and 10 in which the amount of the fluorescent organic pigment added was less than 0.05 wt% or more than 0.3 wt%, Col-L and b values were inappropriate.

As can be seen from the performance evaluation results of the films prepared in the above Examples and Comparative Examples, polyesters of rutile crystal titanium dioxide, sulfonic acid metal salt derivatives, fluorescent organic pigments, CoAl ₂ O ₃ and NH ₄ MnP ₂ O ₇ A polyester film prepared by adding an inorganic pigment mixed at a ratio of 1 to a range of amounts has excellent properties such as glossiness, light transmittance, reflectance and Co1-L, b value, and dispersibility, light resistance and surface. Low resistivity and good usability and printability make it suitable for use in various cards, printing materials and industrial substrates.

[table]

Claims (4)

In the polyester film in which at least 60% by weight of the film constituents are ethylene terephthalate, 1 to 25% by weight of titanium dioxide having rutile crystals having an average particle diameter of 0.1 to 3 µm, 0.01 to 1.0% by weight of an antistatic agent, and fluorescent A polyester film comprising 0.05 to 0.3% by weight of an organic pigment and 0.01 to 1.0% by weight of a 1: 1 mixture of an aluminum cobalt compound and a manganese compound as an inorganic pigment. The polyester film according to claim 1, wherein the Syik fluorescent organic pigment is a bisbenzoazole-based compound having photo-developing characteristics in the short wavelength region of visible light. The polyester film according to claim 1 or 2, wherein the inorganic pigments are bluish CoAl ₂ O ₃ and violet NH ₄ MnP ₂ O ₇ . The polyester film according to claim 1, wherein the antistatic agent is a sulfonic acid metal salt derivative of 1.0 mg KOH / g or less.