KR20090073054A - White polyester film for liquid crystal display reflector - Google Patents

Abstract

[PROBLEMS] To improve not only the durability of a reflecting film but also that of a peripheral member, and to reduce manufacture loss by preventing adhesion of fine foreign materials such as dusts. [MEANS FOR SOLVING PROBLEMS] Provided is a white polyester film for liquid crystal display reflectors, which contains a light stabilizer in a polyester film having fine air bubbles and has an average reflectivity of 97% or more on the surface of at least one side of the film.

Description

White polyester film for liquid crystal display reflector {WHITE POLYESTER FILM FOR LIQUID CRYSTAL DISPLAY REFLECTOR}

TECHNICAL FIELD This invention relates to a white polyester film. Specifically, It is related with the white polyester film which is optimal as a reflecting plate for liquid crystal displays. More specifically, when the liquid crystal screen is illuminated by side light (also called edge light) or in a configuration such as disposing a fluorescent tube directly on the reflective film (called a direct type), a reflecting plate from which a brighter screen is obtained. It is related with the white polyester film for display reflectors which can comprise the base material for substrates.

In recent years, many displays using liquid crystals have been used as display devices for PCs, televisions, and cellular phones. When illuminating these liquid crystal displays, the backlight system which illuminates the light from the back of the conventional display, and the side light system as shown by patent document 1 are widely used for the merit which can be illuminated very thinly and uniformly. The side light method is used to perform various processing such as dot printing or wrinkle processing on one surface of a transparent substrate such as an acrylic plate having a predetermined thickness, and illuminate light uniformly by applying illumination such as a cold cathode tube from the edge of the acrylic plate. The screen is dispersed and a screen having a uniform brightness is obtained. In addition, since the illumination is provided at the edge portion instead of the back of the screen, it can be made thinner than the backlight method. In addition, in order to prevent the illumination light from being avoided on the screen back, it is necessary to provide a reflector on the back of the screen. However, since the reflector is thin and high reflectivity of light is required, fine bubbles are contained inside the film. The white film etc. which were whitened by scattering this are mainly used.

On the other hand, the direct type | mold light system has been employ | adopted for large screens, such as a liquid crystal television. In this system, cold cathode ray tubes are arranged in parallel in the lower part of the liquid crystal display. As the reflecting plate, one formed by flat surface or a part of a cold cathode ray tube formed into a semicircular concave shape is used. Conventionally, the film which added the white pigment, the film which contained the fine bubble inside, or the thing which unfolded these films, a metal plate, a plastic board, etc. has been used. When using the film which contained the micro bubble especially inside, it is excellent in the improvement effect of a brightness | luminance, and uniformity (patent document 2).

The formation of these fine bubbles is achieved by finely dispersing inorganic particles such as high melting point incompatible polymers or barium sulfate in a film base material, for example, polyester, and stretching them (for example, biaxial stretching). At the time of stretching, a void (bubble) is formed around the incompatible polymer particles, and since this exerts a scattering effect on light, it becomes white and high reflectance can be obtained.

Moreover, in the technique of patent document 2, while ensuring the reflectance of the light of wavelength 400-700 nm, and also improving the reflectance of the light of wavelength less than 400 nm, it is made to contain a fluorescent brightener in a cavity containing film. It is taking structure.

In recent years, display devices such as liquid crystal display panels have also been required to display a high level of display capability such as photographic images and moving images, which have not been conventionally required. It is rising. In order to meet these demands, the demand for ultraviolet absorbency and various durability required for the reflector is also increasing.

For example, the characteristics which can suppress deterioration even if it is used for a long time and can use stably are especially requested | required. Therefore, for example, in patent document 3, the joint-containing polyester film which contained the light stabilizer is disclosed in order to ensure stability.

Moreover, generally biaxially-stretched polyester film has a problem that static electricity generate | occur | produces easily and dust adheres at the time of film forming, a process, and a use. In recent years, since the dust greatly influences the production loss with the increase in the size of the screen, the demand for anti-pollution for each member is increasing in the liquid crystal monitor manufacturing process in which the polyester film is used. From this request, in patent document 4, the antifouling effect is acquired by giving an antistatic property to a film. However, the film provided by patent document 4 cannot be applied to the liquid crystal display device which requires light stability, and the optical film which is compatible with light stability and pollution prevention is calculated | required.

Patent Document 1: Japanese Patent Application Laid-Open No. 63-62104

Patent Document 2: Japanese Patent Application Laid-Open No. 4-239540

Patent Document 3: Japanese Patent Application Laid-Open No. 2002-098808

Patent Document 4: Japanese Patent Application Laid-Open No. 10-278204

However, in the prior art, the deterioration of the member is promoted by the ultraviolet rays generated from the fluorescent tube, and the change in temperature and humidity conditions such as in the liquid crystal unit is large in long-term use, so that the member is caused by the difference in thermal expansion coefficient of each member. May occur. At this time, when the contact area of members is large, when the deformation occurs, friction creaks of the members occur. If this squeaking is repeated, the deterioration of the member is promoted and the characteristics deteriorate due to the scratches caused by friction. Moreover, the loss by adhesion of dust in a manufacturing assembly process is also large. If these problems are to be solved only by the addition of a light stabilizer that provides light stability, the addition of particles for the production of unevenness, and the addition of an antistatic agent, not only the deterioration of the optical properties occurs due to coloring or scattering, but also the reaction between the materials. This may occur, and the performance of each material may be denied.

In order to solve this problem, the present invention has the following configuration. In other words,

(1) The white polyester film for liquid crystal display reflecting plates which contains a light stabilizer in the polyester film which has a fine bubble, and whose average reflectance of at least one surface of the said film is 97% or more.

(2) The liquid crystal display reflecting plate as described in (1) which has a structure which the said polyester film laminated | stacked the polyester layer (B) containing a light stabilizer on at least one surface of the polyester layer (A) which has a fine bubble. White polyester film.

(3) Layer (C) containing an antistatic agent is applied to at least one side of the polyester film, and to (1) or (2), wherein the surface specific resistance of the layer (C) is 1 × 10 ¹³ Ω / square or less. The polyester film for liquid crystal display reflectors described.

(4) The white polyester film for liquid crystal display reflecting plates in any one of (1)-(3) whose center surface average roughness Ra of the said polyester film surface is 0.1 or more and 10-point average roughness Rz is 1.0 or more. .

(5) White poly for liquid crystal display reflecting plates in any one of (1)-(4) whose content of the light stabilizer contained in the said polyester film is 0.02 weight% or more and 20 weight% or less with respect to the total weight of a polyester film. Ester film.

(6) The white polyester film for liquid crystal display reflecting plates in any one of (1)-(5) whose optical stabilizer contained in the said polyester film is a malonic ester optical stabilizer.

(7) The white polyester film for liquid crystal display reflecting plates in any one of (1)-(6) whose light stabilizer contained in the said polyester film is 2, 6- naphthalenedicarboxylic acid or its copolymer.

(8) Liquid crystal display of any one of (1)-(7) whose titanium dioxide particle is contained in the said polyester film, and whose content is 1 weight% or more and 40 weight% or less with respect to the total weight of a polyester film. White polyester film for reflecting plates.

(9) (1) to (5), wherein the polyester film contains particles having a mean particle size of 1.0 µm or more (hereinafter, large particle size), and the content thereof is 0.01% by weight or more and 5% by weight or less based on the total weight of the polyester film. The white polyester film for liquid crystal display reflecting plates in any one of (8).

(10) The polyester film for liquid crystal display reflection plates as described in (9) whose said large particle size particle | grain is a silica particle.

(11) The white polyester film for liquid crystal display reflecting plates in any one of (1)-(10) in which a fine bubble is formed by containing the polyester and incompatible thermoplastic resin.

(12) The thermoplastic resin incompatible with the polyester is polymethylpentene, and the average particle diameter in the polyester film is equal to or less than the average particle diameter of the large particle size, and is 5% by weight or more based on the total weight of the polyester film. The white polyester film for liquid crystal display reflectors as described in (11) containing weight% or less.

(13) The white polyester film for liquid crystal display reflecting plates of any one of (1)-(12) whose specific gravity of the said polyester film is 0.5 or more and 1.2 or less.

(14) The white polyester film for liquid crystal display reflecting plates in any one of (1)-(13) in which a fine bubble is formed because the said polyester film contains an inorganic particle.

(15) The inorganic particles contained in order to form the fine bubbles are barium sulfate, and the average particle diameter of the barium sulfate is 0.1 µm or more and 5.0 µm or less, and the average particle diameter of the large particle size is smaller than that of the polyester film. The white polyester film for liquid crystal display reflectors as described in (14) containing 5 to 70 weight% with respect to a total weight.

(16) The white polyester film for liquid crystal display reflecting plates in any one of (1)-(15) whose specific gravity of the said polyester film is 1.2 or more and 1.4 or less.

(17) The polyester film according to any one of (2) to (16), wherein the deep layer portion is a liquid crystal display reflector for the polyester layer (A), and one or both surface layer portions are the polyester layer (B). White polyester film.

(Effects of the Invention)

According to the present invention, it is possible to obtain a white polyester film for a liquid crystal display reflecting plate having both light stability, antifouling property and low friction, thereby improving durability of the polyester film and other peripheral members mounted on the liquid crystal panel. In addition, manufacturing loss due to foreign matter adhesion can be reduced.

1 is a conceptual diagram of a luminance measurement system.

<Description of Symbols for Major Parts of Drawings>

11: fluorescent tube 12: reflective film

13: light guide plate 14: diffusion film

15: luminance meter

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

[Layer Composition]

The polyester film of this invention needs to contain a light stabilizer in the polyester film which has a micro bubble.

The polyester film of the present invention may be either a single layer or a multilayer, but is a laminated structure using the polyester layers (A) and (B), and the polyester layer (A) is a layer containing fine bubbles, at least one of which It is preferable that a polyester layer (B) is a layer which contains a light stabilizer in the point of high reflectance, film forming property, an optical characteristic, and light stability.

It is preferable that especially the polyester film of this invention is a structure which the polyester layer (B) containing an optical stabilizer was laminated | stacked on at least one surface of the polyester layer (A) which has a fine bubble (These laminated forms, Hereinafter referred to as "Form 1").

Moreover, it is also one of the preferable forms to form layer (C) containing an antistatic layer in at least one surface of the polyester film of this invention.

The polyester film of this invention may be comprised from many layers, as long as it contains the structure of this polyester layer (A) and a polyester layer (B). For example, the two-layer constitution of a polyester layer (A) / polyester layer (B) may be sufficient, and the three-layer constitution of a polyester layer (B) / polyester layer (A) / polyester layer (B), or poly The four-layer structure of ester layer (A) / polyester layer (B) / polyester layer (A) / polyester layer (B) may be sufficient. Moreover, the structure of five or more layers may be sufficient. By setting it as a multilayer structure, the characteristic of each layer is expressed in the surface of a laminated polyester film, and various characteristics can be controlled.

Considering the ease and effect on film forming, the form of a two-layered constitution or the three-layered constitution which consists of a polyester layer (B) / polyester layer (A) / polyester layer (B) is preferable. In particular, a three-layer configuration of the form of protecting the polyester layer (A) with the polyester layer (B), that is, the polyester layer (B) / polyester layer (A) / polyester layer (B) is preferable. Moreover, it is preferable that a deep layer part is a polyester layer (A), and the surface layer part of one or both sides is a polyester layer (B).

[Polyester Film]

The polyester constituting the present invention is a polymer obtained by condensation synthesis from diol and dicarboxylic acid, and examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, adipic acid and sebacic acid. Diol is represented by ethylene glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethanol, and the like. Specifically, for example, polymethylene terephthalate, polytetramethylene terephthalate, polyethylene-p-oxybenzoate, poly-1,4-cyclohexylenedimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate and the like Can be mentioned. In the case of the present invention, polyethylene terephthalate (hereinafter sometimes abbreviated as PET) and polyethylene naphthalate are particularly preferable.

Moreover, in this polyester, various well-known additives, for example, antioxidant, antistatic agent, etc. may be added. As the polyester used in the present invention, polyethylene terephthalate is preferable. Polyethylene terephthalate film is excellent in water resistance, durability, chemical resistance and the like.

When polyethylene terephthalate is used as the basic composition, from the viewpoint of film forming stability, preferably 1 mol% or more and 15 mol% or less per total dicarboxylic acid component, more preferably 3 mol% or more and 14 mol% or less, most Preferably, copolyester containing 5 mol% or more and 13 mol% or less of copolymerization components may be used. If it is less than 1 mol%, it may not be able to form into a film when it contains a layer containing inert particle | grains, for example, 31 weight% or more of barium sulfate or titanium dioxide particle. Even if it exceeds 15 mol%, film forming may not be possible.

As this copolymerization component, for example, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, phthalic acid, as a dicarboxylic acid component Sodium sulfoisophthalic acid; and the like. As a diol, ethylene glycol, 1, 4- butanediol, 1, 4- cyclohexane dimethanol, 1, 6- hexanediol, neopentyl glycol, polyalkylene glycol, etc. are mentioned, for example. Especially as a copolymerization component of the polyester used for a polyester layer (A), in order to acquire favorable film forming property, it is preferable to use isophthalic acid and 2, 6- naphthalenedicarboxylic acid.

[Formation of micro bubbles]

In this invention, the average reflectance in the wavelength range of 400-700 nm light needs to be 97% or more in at least one surface of a film. It is because the luminance as an inverse prism type backlight may fall when it is less than 97%. In the present invention, the average reflectance is measured by applying an integrating sphere to Hitachi Hi-Technologies Spectrophotometer (U-3310) and setting the standard white plate (aluminum oxide) to 100% over 400 to 700 nm. From the chart obtained, wavelengths are values obtained by reading and reflecting the reflectance at intervals of 5 nm.

In order to make the reflectance 97% or more, it is important to contain the fine bubbles and the inert inorganic particles inside the film and to whiten them, so that the light scattering action can be exhibited, thereby improving the reflectance. Preferably the reflectance is 98% or more, more preferably 100% or more. Although there is no upper limit in particular about a reflectance, In order to raise a reflectance, it is necessary to increase the addition amount of the incompatible thermoplastic resin or inorganic particle which becomes a bubble-forming nucleating agent, and in that case, it is preferable that it is 110% or less because film forming property may become unstable.

Formation of fine bubbles is achieved by finely dispersing a high melting polyester and an incompatible thermoplastic resin or inorganic particles in a film base material, for example, polyester, and stretching (for example, biaxial stretching). At the time of stretching, voids (bubbles) are formed around the incompatible thermoplastic resin or inorganic particles, and since this exerts a scattering effect on light, it becomes white and high reflectance can be obtained. Preferred incompatible thermoplastic resins and inorganic particles in the present invention will be described later.

[Large particle size]

Moreover, in this invention, it is preferable that the center surface average roughness Ra of the film surface is 0.1 or more, and 10-point average roughness Rz is 1.0 or more. More preferably, Ra is 0.1 or more and less than 1.0, and Rz is 1.0 or more and less than 10.0, More preferably, Ra is 0.1 or more and less than 0.4 and Rz is 1.0 or more and less than 6.0. The numerical values of Ra and Rz are related to the deterioration of the film surface by friction between members. By forming minute irregularities on the surface of the member, friction can be reduced and stability can be improved. In the case where Ra is less than 0.1 and Rz is less than 1.0, deformation of members occurs due to the difference in thermal expansion coefficient of each member when the temperature and humidity conditions are placed in a large environment under the premise of long-term use. However, this repetition accelerates the deterioration of the member. When Ra is 0.4 or more, or Rz is 6.0 or more, the scattering effect by the roughness of a surface may become strong and optical characteristics may fall.

In order to achieve said Ra and Rz, it is preferable to contain large particle size in the polyester film of this invention. Moreover, when the polyester film of this invention has a polyester layer (A) and a polyester layer (B), it is preferable to contain a large particle size in a polyester layer (A) and / or a polyester layer (B). Do.

In addition, a large particle size particle means the particle | grains with the largest average particle diameter (average particle diameter is number average particle diameter. Hereinafter, it is the same in this specification) among the particle | grains contained in a film.

Although the particle | grains used as a large particle size do not matter what kind, but in order to acquire stable film forming property and high optical characteristic, as an inorganic particle, silica particle, titanium dioxide particle, barium sulfate particle, aluminum oxide particle, etc. are preferable, and organic particle | grains are preferable. As an acryl particle | grain, etc. are preferable. Moreover, they can be used individually or in mixture of 2 or more types, Especially, a silica particle is especially preferable from the point of the dispersion diameter stability of particle | grains, or the stability of a film forming.

1.0 micrometer or more is preferable, as for the average particle diameter of a large particle diameter, More preferably, they are 1.0 micrometer or more and 5 micrometers or less, More preferably, they are 3 micrometers or more and 5 micrometers or less.

Moreover, when content of a large particle size makes 100 weight% of total weight of a polyester film, 0.01 weight% or more and 5.0 weight% or less are preferable, More preferably, they are 0.01 weight% or more and 1.0 weight% or less, More preferably, Is 0.01 weight% or more and 0.5 weight% or less.

Moreover, when the polyester film of this invention adopts form 1, it is preferable to contain a large particle size in a polyester layer (A) and / or a polyester layer (B), More preferably, a polyester layer ( It is to contain large particle size in B).

In the case where the polyester layer (B) contains a large particle size, the average particle diameter of the large particle size is preferably 1 µm or more, more preferably 1 µm or more and 5 µm or less, still more preferably 3 µm or more and 5 µm. It is as follows. Moreover, it is preferable that content is 0.01 to 5 weight% with respect to the total weight of a polyester layer (B), More preferably, it is 0.01 to 1 weight%, More preferably, it is 0.01 to 0.5 weight%.

When the average particle diameter of large particle size is less than 1 micrometer, in order to make Ra more than 0.1, it is necessary to make content very high, and scattering of light by a particle may generate | occur | produce, and the optical characteristic may fall. On the other hand, when the average particle diameter is 5 µm or more, surface irregularities are obtained, but scattering of light due to the large particle size may be large, resulting in deterioration of optical properties. In addition, film forming property may deteriorate.

Moreover, when content of a large particle size is 0.01 weight% or less, there are few surface unevenness, and Ra and Rz value may fall. For this reason, friction between members arises and the deterioration of a member may be accelerated. When the silica particles are 5% by weight or more, the optical properties may be lowered due to scattering caused by excess silica particles.

[Incompatible thermoplastics with polyester]

The polyester film of the present invention needs to have fine bubbles in the polyester film. However, as described above, fine bubbles can be formed by containing polyester and an incompatible thermoplastic resin.

As a resin suitable as an incompatible thermoplastic resin, for example, poly-3-methylbutene-1, poly-4-methylpentene-1, polyvinyl-t-butane, 1,4-trans-poly-2,3-dimethyl Butadiene, Polyvinylcyclohexane, Polystyrene, Polymethylstyrene, Polydimethylstyrene, Polyfluorostyrene, Poly-2-methyl-4-fluorostyrene, Polyvinyl-t-butylether, cellulose triacetate, cellulose tripropio And polymers having a melting point of 200 ° C. or higher selected from nate, polyvinyl fluoride, polychlorotrifluoroethylene, and the like. Especially, polyolefin, especially polymethylpentene is preferable with respect to a polyester base material.

As incompatible thermoplastic resin addition amount, when the total weight of the whole polyester film is 100 weight%, it is preferable that they are 5 weight% or more and 25 weight% or less.

Moreover, when the polyester film of this invention adopts Form 1, it is preferable to contain incompatible thermoplastic resin in a polyester layer (A) and / or a polyester layer (B), More preferably, a polyester layer (A) is made to contain incompatible thermoplastic resin. When incompatible thermoplastic resin is contained in a polyester layer (A), it is preferable that content is 5 weight% or more and 25 weight% or less with respect to the total weight of a polyester layer (A), More preferably, it is 10 weight% or more 25 It is weight% or less.

If the content is too small than this, the effect of whitening is lessened, and it is difficult to obtain a high reflectance. If the content is too high, mechanical properties such as strength of the film itself may be too low.

It is more preferable that this incompatible thermoplastic resin is disperse | distributed uniformly. By uniform dispersion | distribution, a bubble is formed uniformly in a film, and the degree of whitening, and also a reflectance becomes uniform. In order to uniformly disperse the incompatible thermoplastic resin, it is effective to add a low specific gravity agent as a dispersion aid. A low specific gravity agent is a compound which has an effect which makes specific gravity small, and the effect is confirmed by a specific compound. For example, about polyester, polyalkylene glycol, such as polyethyleneglycol, methoxy polyethyleneglycol, polytetramethylene glycol, polypropylene glycol, an ethylene oxide / propylene oxide copolymer, sodium dodecylbenzene sulfonate, sodium alkyl sulfonate Salts, glycerin monostearate, tetrabutylphosphonium paraaminobenzenesulfonate and the like. In the case of the present invention, polyalkylene glycol is particularly preferred, and polyethylene glycol is particularly preferred. In addition, copolymers of polybutylene terephthalate and polytetramethylene glycol are also preferably used to improve the dispersibility of incompatible thermoplastic resins. As addition amount, 3 weight% or more and 20 weight% or less are preferable with respect to the total weight of a polyester film, Especially preferably, they are 10 weight% or more and 25 weight% or less. In addition, when the polyester film of this invention adopts form 1, and contains a thermoplastic resin incompatible in a polyester layer (A), the addition amount of a low specific gravity agent is 3 weight based on the total weight of a polyester layer (A). It is preferably at least 25% by weight, particularly preferably at least 10% by weight and at most 20% by weight. When the addition amount of the low specific gravity agent is too small, the effect of the addition becomes thin, and when too large, there is a possibility that the original characteristics of the film base material may be impaired. Such a low specific gravity agent can be previously added to a film base material polymer, and can be adjusted as a master polymer (master chip).

By containing fine bubbles in a white polyester film using an incompatible thermoplastic resin, the apparent specific gravity of the polyester film is lower than that of a normal polyester film. In addition, the addition of a low specific gravity agent lowers the specific gravity. That is, a white and light film is obtained. It is preferable that specific gravity is 0.5 or more and 1.2 or less in order to make this white polyester film lightweight, maintaining the mechanical characteristics as a base material for liquid crystal display reflecting plates.

In order to make specific gravity 0.5 or more and 1.2 or less, when using a low specific gravity agent, for example, polymethylpentene of specific gravity 0.83, 5-25 weight% or less is contained with respect to the whole polyester film, and a draw ratio is 2.5 here. It can achieve by setting it as -4.5. In particular, when the polyester film of the present invention adopts Form 1, when the apparent specific gravity is in the range of the present invention, a large number of fine bubbles can be present while maintaining the film strength, and a high reflectance can be obtained. That is, when used as a liquid crystal display reflector, the brightness | luminance which is remarkably excellent in the brightness of a screen is exhibited.

Moreover, when specific gravity of the white polyester film for liquid crystal display reflecting plates of this invention is used, it is 0.5 or more and 1.2 or less, Preferably it is 0.5 or more and 1.0 or less, More preferably, it is 0.55 or more and 0.8 or less. It is preferable to obtain reflectance.

It is preferable that the average particle diameter of the incompatible thermoplastic resin contained in a polyester film is below the average particle diameter of large particle size (if there is no large particle size particle | grain, less than 1.0 micrometer). More preferably, they are below the average particle diameter of large particle size, and are 0.2 micrometer or more and 5 micrometer or less, More preferably, they are 0.3 micrometer or more and 3 micrometer or less. In addition, although an incompatible thermoplastic resin may correspond to a large particle size, in this case, the average particle diameter of a large particle size and the average particle diameter of an incompatible thermoplastic resin become the same. In addition, when large particle size is not added in a polyester film, the average particle diameter of incompatible thermoplastic resin is not specifically limited, Preferably it is 0.2 micrometer or more and less than 1 micrometer, More preferably, 0.3 micrometer or more and less than 1 micrometer. to be.

If the particle diameter of the incompatible thermoplastic resin is smaller than the above range, it is not preferable because fine bubbles containing the incompatible thermoplastic resin as a nucleus are not formed. On the other hand, when larger than the said range, since bubble size becomes large and film intensity | strength and film forming stability fall, it is unpreferable.

[Inorganic particles forming micro bubbles]

Although the above-mentioned incompatible thermoplastic resin can be used suitably in order to form a micro bubble in this invention, It is also one of the preferable forms to use an inorganic particle in order to form a micro bubble.

In the case of using inorganic particles, in order to obtain high optical properties and stable film forming properties, titanium dioxide, barium sulfate, calcium sulfate, magnesium sulfate, aluminum oxide, zinc oxide, magnesium oxide, calcium carbonate, barium carbonate, silica, etc. desirable. Moreover, although they can be used individually or in mixture of 2 or more types, barium sulfate particle | grains and titanium dioxide particle are especially preferable, since high optical characteristic and film forming stability are acquired especially.

Moreover, the large particle size mentioned above can also be used as an inorganic particle which forms a micro bubble in the range which does not impair an optical characteristic.

[Barium Sulfate Particles]

When using barium sulfate as an inorganic particle which forms a micro bubble, it is preferable to contain 5 weight% or more and 70 weight% or less of barium sulfate particle with respect to the total weight of a polyester film. More preferably, they are 10 weight% or more and 55 weight% or less, More preferably, they are 10 weight% or more and 50 weight% or less.

Moreover, when the polyester film of this invention has a polyester layer (A), it is preferable to contain 21 weight% or more and 70 weight% or less of barium sulfate particle with respect to the total weight of a polyester layer (A). More preferably, they are 23 weight% or more and 55 weight% or less, More preferably, they are 25 weight% or more and 50 weight% or less.

Moreover, when the polyester film of this invention has a polyester layer (B), it is preferable to contain 0.1 weight% or more and 15 weight% or less of barium sulfate particle with respect to the total weight of a polyester layer (B). More preferably, they are 0.2 weight% or more and 14 weight% or less, More preferably, they are 0.5 weight% or more and 13 weight% or less.

When content is less than the lower limit of this range, scattered light by barium sulfate particle | grains may run out and it may be impossible to acquire sufficient reflection performance. If the amount is larger than the upper limit of this range, the film forming stability may be significantly reduced.

Moreover, it is preferable that the average particle diameter of the barium sulfate contained in a polyester film is below the average particle diameter of large particle size particle | grains (less than 1.0 micrometer in the case of no large particle size particle), and is 0.1 micrometer or more and 10 micrometer or less. More preferably, it is below the average particle diameter of a large particle size, and is 0.3 micrometer or more and 8 micrometers or less, More preferably, it is 0.5 micrometer or more and 5 micrometers or less. By using barium sulfate having an average particle diameter in this range, good dispersibility and film forming stability can be obtained. In addition, barium sulfate may be plate shape or spherical shape.

In addition, although the barium sulfate particle | grains correspond to a large particle size, in this case, the average particle diameter of a large particle size particle and the average particle diameter of the thermoplastic resin of barium sulfate become the same.

When no large particle size particles are added in the polyester film, the average particle diameter of barium sulfate is preferably 0.1 μm or more and less than 1 μm, more preferably 0.3 μm or more and less than 1 μm, still more preferably 0.5 μm or more 1 Less than 탆.

By including fine bubbles in the white polyester film by using such inorganic particles, the apparent specific gravity of the polyester film is lower than that of a conventional polyester film. When the bubble is contained by using inorganic particles such as barium sulfate, in order to satisfy the optical properties while maintaining the mechanical properties as the substrate for the liquid crystal display reflecting plate, the specific gravity is preferably 1.2 or more and 1.4 or less, and more preferably 1.2 or more. It is preferable that it is 1.35 or less in order to obtain a higher reflectance. If the apparent specific gravity is in the range of the present invention, a large number of fine bubbles can be present while maintaining the film strength, and a high reflectance can be obtained. That is, when used as a liquid crystal display reflector, the brightness | luminance which is remarkably excellent in the brightness of a screen is exhibited.

[Formulation of Particles]

Various methods can be used as a method of mix | blending inorganic particles, such as barium sulfate particle | grains and rutile titanium dioxide, with a polyester composition. The following method can be mentioned as the typical method. (A) A method of adding particles before the end of the transesterification or esterification reaction in the synthesis of polyester, or a method of adding the particles before the start of the polycondensation reaction. (B) Method of melt-kneading by adding particles to polyester. (C) The method of producing the master pellet which added the particle | grains abundantly in the method of said (A) or (B), kneading these and the polyester which does not contain an additive, and containing a predetermined amount of additives. (D) A method of using the master pellet of (C) as it is.

As a mixing method of incompatible thermoplastic resin and barium sulfate particle | grains, it is preferable to take the method of said (C) or (d) especially from a viewpoint of dispersibility of particle | grains.

The incompatible thermoplastic resin and the barium sulfate particles are formed using a nonwoven fabric filter having an average aperture of 10 to 100 μm, preferably an average aperture of 15 to 50 μm, of stainless steel fine wire having a wire diameter of 20 μm or less as a filter during film formation. It is preferable to filter the molten polymer immediately before extruding from the die. In this way, the number of coarse aggregated particles can be reduced.

[Photo stabilizer]

Since the white polyester film of this invention is exposed to the ultraviolet-ray derived from the light from the exterior at the time of storage, and is exposed to the ultraviolet-ray from the fluorescent tube attached to a backlight unit at the time of use, use of a light stabilizer is necessary.

In this invention, it is preferable to have a light stabilizer in a polyester layer (B). Moreover, you may contain an optical stabilizer in the polyester layer (A) in the range which does not impair a characteristic. It is preferable that content of a light stabilizer is 0.02 weight% or more and 20 weight% or less with respect to the total weight of the whole polyester film, More preferably, they are 0.1 weight% or more and 15 weight% or less, and also 0.5 weight% or more and 15 weight% or less. desirable.

Moreover, when the polyester film of this invention adopts form 1, it is preferable to make a predetermined amount contain the light stabilizer in the polyester layer (B). It is preferable that content of the light stabilizer to a polyester layer (B) is 0.1-20 weight% with respect to the total weight of a polyester layer (B), More preferably, it is 0.5-15 weight%, Furthermore, 1-5 weight% Is most preferred.

When the content of the light stabilizer is less than 0.1% by weight, the light resistance becomes insufficient, and there is a problem that the film deteriorates during the use for a long time, and the reflection characteristics thereof tend to be lowered. On the other hand, when it exceeds 20 weight%, reflection characteristics may fall by coloring with a light stabilizer, and it is unpreferable.

The polyester film for liquid crystal display reflecting plates may enter the thermal process in post-processing processes, such as application | coating, drying, and vapor deposition, after film forming. Moreover, the film which receives the heat | fever directly from the fluorescent tube attached to a backlight unit after installation, and the optical stabilizer used by this invention is excellent in heat resistance, in order to be able to withstand long-term storage in a roll state, It is preferable to select ones having good compatibility and uniform dispersion and having little coloration and which do not adversely affect the reflective properties of the resin and the film. It will not specifically limit, if it is a light stabilizer which satisfy | fills the former conditions, For example, ultraviolet absorbers, such as salicylic acid type, a benzophenone type, a benzotriazole type, a cyanoacrylate type, a triazine type, and a malonic acid ester type, a hinderedamine Various kinds of dicarboxylic acid components having light stability such as ultraviolet stabilizers such as system and naphthalenedicarboxylic acid can be applied, but in particular, in order not to have an absorption peak in the long wavelength region near 350 nm near the visible light region Malonic ester type and naphthalenedicarboxylic acid which are excellent in this are especially preferable. More specific application examples are as follows.

(UV absorber)

Malonic ester system: tetraethyl-2,2 '-(1,4-phenylene-dimethylidene) -bismalonate, malonic acid [(4-methoxyphenyl) -methylene] -dimethyl ester

Salicylic acid system: p-t-butylphenyl salicylate, p-octylphenyl salicylate

Benzophenone series: 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2,2'-4,4 '-Tetrahydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, bis (2-methoxy- 4-hydroxy-5-benzoylphenyl) methane

Benzotriazole type: 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-butylphenyl) benzotriazole, 2- (2'-hydroxy- 3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'methylphenyl) -5-chlorobenzotriazole, 2- (2' -Hydroxy-3 ', 5'-di-t-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3', 5'-di-t-butylphenyl) -5-chloro Benzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-amylphenyl) benzotriazole , 2,2'methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2 (2'hydroxy-5'- Methacryloxyphenyl) -2H-benzotriazole, 2- [2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidemethyl) -5'methylphenyl] benzo Triazole

Cyanoacrylate type: ethyl-2-cyano-3,3'-diphenyl acrylate

Triazine type: 2- (2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine, 2,4-bis [2-hydroxy -4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3,5-triazine

Other than the above: 2-ethoxy-2'-ethyloxalic acid bisanilide, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol , 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxyphenyl, 2-ethyl, 2'-ethoxyoxalanilide.

(Ultraviolet stabilizer)

Hindamine type: bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl succinate dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6 , 6-tetramethylpiperidine polycondensate

Other than the above: Nikkel bis (octylphenyl) sulfide, [2-thiobis (4-t-octylphenolate)]-n-butylamine nickel, nickel complex-3,5-di-t-butyl-4-hydroxy Benzyl-phosphate monoethylate, nickel-dibutyldithiocarbamate, 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4'-hydroxybenzoate, 2, 4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4-hydroxybenzoate, 2,2,4,4-tetramethyl-7-oxy-3,20-diazo- Disspiro- [5,1,11,2] -henicoic acid-21-one, 2,2,4,4-tetramethyl-21-oxo-7-oxy-3,20-diazodispiro [5.1. 11.2] -henicoic acid-20-propionic acid dodecyl ester / tetradecyl ester, 2,2,4,4-tetramethyl-7-oxy-3,20-diazo-20 (2,3-epoxy-propyl) Polymer of disspiro- [5.1.11.2] -henicoic acid-21-one, propanediic acid [(4-methoxyphenyl) -methylene]-, bis (1,2,2,6,6-pentamethyl-4 -Piperidinyl) ester, 2,6-naphthalenedicarboxylic acid.

Among these light stabilizers, tetraethyl-2,2 '-(1,4-phenylene-dimethylidene) -bismalonate excellent in compatibility with polyester, malonic acid [(4-methoxyphenyl) -methylene] -Dimethyl ester, 2,2'-4,4'-tetrahydroxybenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenyl) methane, 2,2'-methylenebis [4- ( 1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (4,6-diphenyl-1,3,5-triazine-2- The application of the mono) -5-[(hexyl) oxy] -phenol and 2,6-naphthalenedicarboxylic acid (it may abbreviate as "NDC" hereafter) is preferable.

The said light stabilizer may be individual, or may use 2 or more types together, or a polymer may be sufficient as it. Moreover, the copolymer component with respect to polyester may be sufficient.

In particular, as long as it is a photo-stable dicarboxylic acid like 2, 6- naphthalenedicarboxylic acid, the polyester (including copolymer) which comprised the said dicarboxylic acid as a dicarboxylic acid component may be sufficient. Specific examples thereof include polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), and a copolymer obtained by copolymerizing 2,6-naphthalenedicarboxylic acid to PET. In addition, in that case, content of the light stabilizer in a film shall be an amount of the light stabilizer component which exists in polyester etc. (including a copolymer).

Moreover, you may add an inorganic light stabilizer in the range in which there is no fall of a performance. Inorganic light stabilizers include titanium oxide, zinc oxide and the like, but titanium dioxide is preferably used for improving light stability.

When the inorganic light stabilizer is used, the inorganic light stabilizer may also serve as the above-mentioned large particle size particles or inorganic particles forming fine bubbles.

When titanium dioxide is added, the average particle diameter is not particularly limited as long as the optical properties are not impaired. More preferably, they are below the average particle diameter of large particle size, and are 0.1 micrometer or more and 5 micrometers or less.

The content of titanium dioxide is preferably 1% by weight or more and 40% by weight or less with respect to the total weight of the polyester film, more preferably 5% by weight or more and 20% by weight or less, still more preferably 5% by weight or more and 15% by weight. % Or less When the content of titanium dioxide is more than 40% by weight, the film forming becomes unstable, and the optical properties may decrease due to the light hiding property of the titanium dioxide particles. On the other hand, when the addition amount of titanium dioxide is less than 1 weight%, there is no decrease in optical performance, but the improvement effect of light stability may be hard to express.

Moreover, when the polyester film of this invention adopts Form 1, it is preferable to make a predetermined amount contain titanium dioxide in the polyester layer (B). Moreover, you may contain titanium dioxide in the polyester layer (A) in the range which does not impair a characteristic. It is preferable that content of the light stabilizer to a polyester layer (B) is 5-20 weight% with respect to the total weight of a polyester layer (B), More preferably, it is 5-15 weight%. When the content of titanium dioxide is more than 20% by weight, the optical properties may be deteriorated due to the light hiding property of the titanium dioxide particles. On the other hand, when the addition amount of titanium dioxide is less than 5% by weight, there is no decrease in optical performance, but the effect of improving the light stability may be hard to be expressed.

The light stabilizer has an absorption wavelength peak in light in the ultraviolet region, particularly in the wavelength region of 340 nm to 350 nm, but the absorption region of light reaches the visible light region (wavelength 380 nm or more) in most of them. This becomes yellowish when the light stabilizer is added to the white polyester film. When used as a white polyester film for liquid crystal display reflectors due to this yellow color, the brightness is lowered and the design of other optical members such as fluorescent tubes is also affected. For this reason, the light stabilizer may be required to be able to suppress the yellow taste low.

Light stabilizers in which the absorption wavelength is not in the visible range, for example tetraethyl-2,2 '-(1,4-phenylene-dimethylidene) -bismalonate, malonic acid [(4-methoxyphenyl) -methylene] By using -dimethyl ester, 2-ethyl, 2'-ethoxyoxalanilide, and 2,6-naphthalenedicarboxylic acid, yellow taste can be suppressed low.

As described above, malonic acid [(4-methoxyphenyl) -methylene] -dimethyl ester and 2,6-naphthalenedicarboxylic acid are the most from the viewpoint of compatibility with polyester and no absorption wavelength in the visible light region. desirable.

[Layer (C) containing Antistatic Agent]

It is unpreferable that the white polyester film of this invention adheres dust from the use especially in a process and an assembly process. Therefore, it is preferable to form the layer (C) containing an antistatic agent in at least one surface of a white polyester film.

In the present invention, the layer (C) containing an antistatic agent is preferably a coating film layer formed by stretching the aqueous coating liquid in at least one direction after coating and drying, for the purpose of preventing environmental pollution and explosion-proof properties during film production, It is preferable to form in the manufacturing process of carrying out the biaxial orientation of the base film which consists of a polyester layer (A) and a polyester layer (B). Although the timing of the said extending | stretching is not specifically limited, It is preferable to extend | stretch in at least 1 axial direction after application | coating liquid application | coating. Specifically, a method of biaxial stretching after coating the aqueous coating liquid, or a method of applying the aqueous coating liquid after longitudinal (longitudinal direction of the film) stretching and transverse stretching is preferably used. As the coating method of the aqueous coating liquid, various coating methods, for example, a reverse coating method, a gravure coating method, a rod coating method, a bar coating method using a metalling bar, a die coating method, a spray coating method and the like can be preferably used. Although it is possible, it is not limited to these.

The aqueous coating liquid may contain a small amount of an organic solvent for the purpose of helping to stabilize the coating liquid. As this organic solvent, methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, isopropanol can be illustrated. Two or more types of organic solvents may be contained.

In the present invention, the aqueous coating liquid includes a crosslinking agent such as other surfactants, ultraviolet absorbers, pigments, lubricants, antiblocking agents, water-soluble polymer resins, oxazolines, melamines, epoxies, aziridine, and the like within the range of not impairing the object of the present invention. Additives of other antistatic agents may be blended.

As for solid content concentration in the aqueous coating liquid in this invention, 5-30 weight% is preferable from a viewpoint of the external appearance of a coating film, More preferably, it is 5-20%.

As for the thickness of the layer (C) containing an antistatic agent, 0.01-2 micrometers is preferable, More preferably, it is 0.1-1 micrometer. If the thickness is too thin, solvent resistance or antistatic property may be insufficient, and if the thickness is too thick, the activity may be reduced.

In the present invention, the surface resistivity of the layer (C) containing an antistatic agent is 1 × 10 ¹³ Ω / □ or less, preferably 10 ⁷ Ω / □ or more and 10 ¹³ at 23 ° C. and 50% relative humidity. It is preferable that it is ohm / square or less. If the surface resistivity is less than 10 ⁷ Ω / □, the interfacial adhesion and film forming property may be inferior. If the surface resistivity is greater than 10 ¹³ Ω / □, the antistatic property may be insufficient and consequently the contamination prevention may be insufficient. have. In the present invention, the surface specific resistance value is measured by the following method, for example. When using a surface resistivity measuring instrument (MMAII-17A) manufactured by Kawaguchi Denki Seisakusho, after leaving the sample for 1 day in an atmosphere of 23 ° C. × 50% RH, after leaving it at a voltage of 500 V for 1 minute, Measure the surface resistivity. Here, the electrode is made of the same company (model number P-618), and a concentric circular electrode having an outer diameter of 90 mm for the main electrode and an inner diameter of 45 mm for the counter electrode.

[Antistatic Agent (P)]

As antistatic agent (P) added to the layer (C) containing an antistatic agent in order to express antistatic property (surface specific resistance value) mentioned above, metal powder, a tin oxide-antimony type electrically conductive agent, surfactant which has antistatic property Although the antistatic agent to be used may be heat-resistant, have low coloration, and do not adversely affect the reflective properties of the resin and the film from requests such as the requirements required for the selection of the light stabilizer described above. The choice of one is preferred. Although it will not specifically limit, if it is an antistatic agent which satisfy | fills the former conditions, For example, the polycationic polymer (P-1) containing the compound which consists of a polyethylene sulfonate group etc., a compound containing a carboxylate group, etc., and a conductive polymer It is preferable that it is a polymer (P-2). The addition amount of antistatic agent is 10-60 mass parts, Preferably it is 15-50 mass parts with respect to the total weight of the layer (C) containing an antistatic agent in the case of the antistatic agent (P-1) which consists of a polycationic polymer. If the ratio is less than 10 parts by mass, the antistatic property is lowered, and if it is 60 parts by mass or more, the layer (C) having an antistatic agent is destabilized, coagulation, cracking, etc. occur, and the film is cloudy and antistatic property is deteriorated. Heat resistance will also fall easily.

In the case of an electroconductive high polymer (P-2), 5-40 mass parts is preferable at the ratio with respect to the total weight of the layer (C) containing an antistatic agent, More preferably, it is 5-30 mass parts. If it is 5 mass parts or less, antistatic property will become low, On the other hand, if it is 40 mass parts or more, the layer (C) which has an antistatic agent will become unstable, agglomeration, a crack, etc. will occur, a film will become cloudy, antistatic property falls, and heat resistance It is also easy to fall. In addition, the detail of a polycationic polymer (P-1) and a conductive polymer polymer (P-2) is described below.

[Polycationic Polymer (P-1)]

The polycationic polymer (P-1) which can be selected as an antistatic agent in the present invention is a compound composed of polyethylene sulfonate group or the like from a request that has heat resistance, little coloration and does not adversely affect the reflective properties of the resin and the film. Co-polyester containing the compound containing a carboxylate group, etc. is preferable.

Examples of the cationic component of the sulfonate group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and the like, but are limited thereto. It is not. As a cationic component of a carboxylate group, for example, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methyl cyclohexene-1,2,3-tricarboxylic acid, trimesic acid , 1,2,3,4-butanetetracarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-cyclohexene-1,2-dicarboxylic acid, cyclopentanetetracarboxylic acid , 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, ethylene glycol bistrimellitate, 2,2 ', 3,3'-diphenyltetracar Acid, thiophene-2,3,4,5- tetracarboxylic acid, ethylene tetracarboxylic acid, etc. are mentioned, It is not limited to these. Among these sulfonic acids and carboxylic acids, application of sulfo terephthalic acid, 5-sulfoisophthalic acid and 4-sulfoisophthalic acid, which is excellent in heat resistance and adhesiveness with the polyester layer (A) or polyester layer (B) described later. Is most preferred.

Examples of the anion components of the sulfonate group and the carboxylate group include ammonium ions, potassium ions, sodium ions, and lithium ions. However, ammonium ions and lithium ions are preferable in terms of antistatic properties and film formation properties.

As a poly cationic polymer, the polymer which makes the structure represented by following formula (I) as a main repeating unit can also be used preferably.

(Wherein R ¹ and R ² are each H or CH ₃ , R ³ is an alkylene group having 2 to 10 carbon atoms, R ⁴ and R ⁵ are each a saturated hydrocarbon group having 1 to 5 carbon atoms, and R ⁶ is carbon number) Is an alkylene group having 2 to 10, p is a number from 1 to 20, q is a number from 1 to 40, Y ⁻ is a halogen ion, a mono or polyhalogenated alkyl ion, a nitrate ion, a sulfate ion, an alkyl sulfate ion, a sulfonate . an ion or an alkyl sulfonate ion) of an antistatic agent of the formula (ⅰ), formula (ⅰ) in the Y ^- is R ⁷ SO ₃ ^- alkyl sulfonate ion represented by the following (note that, R ⁷ has a carbon number of 1 to 5 of a saturated hydrocarbon _{^{group), - (OR 3) m}} - R 3 is an ethylene group, p is the number of ^{1~20, - (R 6 O)} n - R 6 is an ethylene group, q is 1 to The number of 40 is preferable because the adhesion between the coating film and the polyester film and the heat resistance of the coating film are good, and in particular, the antistatic properties are excellent.

This poly cationic polymer (P-1) can be preferably manufactured by the following method, for example. That is, the acrylic ester monomer is a polyacrylic acid ester having a weight average molecular weight of 2000 to 100,000 by emulsion polymerization, followed by N, N-dialkylaminoalkylamine (for example, N, N-dimethylaminopropylamine, N, N -Diethylaminopropylamine, etc.), and amidation, and finally, a quaternary hydroxyalkylation reaction can be performed to introduce a quaternary cation pair.

In the polycationic polymer (P-1), Y ⁻ in the formula (I) is CH ₃ SO ₃ ⁻ , C ₂ H ₅ SO ₃ ⁻ , or C ₃ H ₇ SO ₃ ⁻ , and — (OR ³ ) _p -Is-(OC ₂ H ₄ ) _p- , and it is preferable that p is 1-5. In addition,-(R ⁶ O) _q - _is- (C ₂ H ₄ O) _q- , and it is preferable that q is 1-10.

As polycationic polymer (P-1), the polymer represented by following formula (II) and (III) can also be used preferably.

R ¹¹ and R ¹² are each an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, an aryl group, and an aralkyl group. Among these, alkyl groups having 1 to 6 carbon atoms are preferable.

Said R <^13> -R <^16> is a C1-C10 alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, etc., respectively, R <^17> , R <^18> is a C2-C10 alkylene group, a cycloalkylene group, an arylene group, an aralkyl, respectively It is a divalent aliphatic group containing a benzene group and hetero atom (O, N, etc.). As this aliphatic group, -CH (OH) CH _2- , -CH ₂ CH (OH) CH _2- , -CH ₂ CH ₂ CH ₂ NHCOCH ₂ CH ₂ CH ₂ -are exemplified.

These can also be used as a homopolymer by copolymerizing with another unsaturated monomer. When copolymerizing and using with another unsaturated monomer, it is preferable that the said repeating unit is comprised by 50 mol% or more. If it is less than 50 mol%, antistatic property is lacking. As another unsaturated monomer, methyl acrylate, ethyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate, methyl crotonate, Glycidyl methacrylate, acryl methacrylate, acrylamide, methacrylamide, N-metholacrylamide, ethylene, styrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, divinylbenzene And acrylic acid, methacrylic acid, maleic acid and fumaric acid.

[Conductive High Polymer (P-2)]

Examples of the conductive polymer polymer (P-2) that can be selected in the present invention include an antistatic polymer obtained by polymerizing a thiophene and / or a thiophene derivative, and an antistatic polymer obtained by polymerizing a pyrrole and / or pyrrole derivative. Can be.

The antistatic polymer obtained by polymerizing a thiophene and / or a thiophene derivative is a homopolymer or copolymer whose main component is a unit represented by the following formula (I) and / or formula (II), and other polymerized units The copolymer containing a small amount as a copolymerization component may be sufficient.

In Formula (I), R ¹ and R ² each represent a hydrogen element (-H), an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group or an aromatic hydrocarbon group, a hydroxyl group (-OH), and a group having a hydroxyl group at the terminal thereof. (-R ³ OH: R ³ is a C1-C20 divalent hydrocarbon group (e.g., alkylene group, arylene group, cycloalkylene group, alkylene arylene group, etc.)), alkoxy group (-OR ⁴ : R ⁴ is a hydrocarbon group having 1 to 20 carbon atoms, a group having an alkoxy group at the terminal (-R ³ OR ⁵ : R ⁵ is an alkyl group having 1 to 4 carbon atoms), a carboxyl group (-COOH), a carboxyl group (-COOM: M is Alkali metal elements, quaternary amines or tetraphosphonium), groups having a carboxyl group at the terminal (-R ³ COOH), groups having a carboxyl group at the terminal (-R ³ COOM), ester group (-COOR ⁵ ), Group having terminal ester group (-R ³ COOR ⁵ ), sulfonic acid group (-SO ₃ H), sulfonate group (-SO ₃ M), terminal having sulfonate group (-R ³ SO ₃ M), sulfonyl group (-SO ₂ R ⁴ ), sulfonyl group at the terminal Group having (-R ³ SO ₂ R ⁴ ), sulfenyl group (-S (= O) R ⁴ ), group having sulfenyl group at the terminal (-R ³ S (= O) R ⁴ ), acyl group (-C (= O) R ⁶ : R ⁶ has a C1-C10 hydrocarbon group), a group having an acyl group at the terminal (-R ³ C (= O) R ⁶ ), an amino group (-NH ₂ ), a terminal amino group Group (-R ³ NH ₂ ), a group in which part or all of hydrogen elements of amino group are substituted (-NR ⁷ R ⁸ : R ⁷ is hydrogen element, alkyl group of 1 to 3 carbon atoms, -CH ₂ OH or -CH ₂ OR ⁶ , R ⁸ is an alkyl group having 1 to 3 carbon atoms, -CH ₂ OH or -CH ₂ OR ⁶ ), a group (-R ³ NR ⁷ R ⁸ ) having a terminal substituted part or all of the hydrogen element of the amino group, Carbamoyl group (-CONH ₂ ), a group having a carbamoyl group (-R ³ CONH ₂ or R ³ NHCONH ₂ ) at the terminal, a group in which part or all of the hydrogen element of the carbamoyl group is substituted (-CONR ⁷ R ⁸ ), A group (-R ³ CONR ⁷ R ⁸ ), a halogen group (-F, -Cl, -Br, -I), R ⁴ having a terminal at which some or all of the hydrogen elements of the carbamoyl group are substituted Group part of hydrogen atom is substituted with a halogen ^{atom, - [NR 1 R 2 R} 9+] [X -] group (R ⁹ is a hydrogen atom or a hydrocarbon group of a carbon number of 1~20, X is represented by ^- is F ^{- , Cl -, Br -, I} -, R 1 OSO 3 -, R 1 SO 3 -, NO 3 - or R ¹ COO ^- ions), phosphate group (-P (-O) (OM) indicated by ₂₎ And a group having a phosphate group (-R ³ P (= O) (OM) ₂ ), an oxirane group, or an oxirane group at the terminal.

In addition, in order to make an antistatic property favorable in an antistatic polymer obtained by superposing | polymerizing a thiophene and / or a thiophene derivative, 0.1-500 weight part of dopants may be mix | blended with respect to 100 weight part of antistatic polymers, for example. Can be. Examples of the dopant include LiCl, R ¹⁰ COOLi (R ¹⁰ : a saturated hydrocarbon group having 1 to 30 carbon atoms), R ¹⁰ SO ₃ Li, R ¹⁰ COONa, R ¹⁰ SO ₃ Na, R ¹⁰ COOK, R ¹⁰ SO ₃ K, Tetraethylammonium, I ₂ , BF ₃ Na, BF ₄ Na, HClO ₄ , CF ₃ SO ₃ H, FeCl ₃ , tetracyanoquinoline (TCNQ), Na ₂ B ₁₀ Cl ₁₀ , phthalocyanine, porphyrin, glutamine III, alkyl And sulfonic acid salts, polystyrene sulfonic acid, polystyrene sulfonic acid Na (K, Li) salts, styrene styrene sulfonic acid Na (K, Li) salt copolymers, styrene sulfonic acid anions and styrene sulfonic acid styrene sulfonic acid anion copolymers.

In particular, it is the homopolymer or copolymer which has the unit represented by the said Formula (II) as a main component, and what combined polystyrene sulfonic acid as a doping agent (following formula (IV)) is preferable.

The antistatic polymer obtained by polymerizing a pyrrole and / or a pyrrole derivative is, for example, a homopolymer or copolymer having a unit represented by the following structural formula as a main component, and a copolymer containing a small amount of polymerized units as a copolymerization component. good.

Here, R ¹ is hydrogen or an alkyl group, and R ² to R ³ are each a hydrogen, an alkyl group, a carboxylic acid (salt) group or a sulfonic acid (salt) group-containing group, a halogen-containing group, an ester group or an ether group.

An antistatic polymer can be manufactured by superposing | polymerizing these pyrrole and a pyrrole derivative by a well-known method (for example, oxidative polymerization method, electrolytic polymerization method, etc.). The pyrrole, as the pyrrole derivatives, R ¹ ~R ³ is hydrogen of pyrrole, R ^1, R ³ is hydrogen, R ² is an alkyl group of pyrrole derivatives, R ¹ is hydrogen, R ² and R ³ is an alkyl group of pyrrole derivatives Can be illustrated preferably. Examples of the pyrrole derivatives include N-substituted pyrroles, such as pyrrole and N-alkylpyrrole, 3-alkylpyrrole, 3,4-dialkyl having a C1 to C6 alkyl group, an alkoxy group or a halogen group at the 3 position or 3 or 4 position. Pyrrole, 3-alkoxypyrrole, 3,4- dialkoxypyrrole, 3-chloropyrrole, and 3,4-dichloropyrrole are mentioned preferably.

[Vehicle material (Q)]

Moreover, as a vehicle material of the layer (C) which has an antistatic agent, film formability improves remarkably by selecting the component which has interface adhesiveness with a polyester layer (A) or a polyester layer (B). Although it will not specifically limit if it is a component which satisfy | fills this condition, Although polyester resin, an acrylic resin, a urethane resin, an epoxy resin, a silicone resin, a urea resin, a phenol resin, etc. are mentioned, A copolymerization polyester resin and a copolymerization acrylic resin are used. It is desirable to. As an acid component which comprises this co-polyester resin, terephthalic acid, isophthalic acid, a phthalic acid, 2, 6- naphthalenedicarboxylic acid, 1, 4- cyclohexanedicarboxylic acid, adipic acid, sebacic acid, phenyl indane dicarboxylic acid Acids, dimer acids, etc. can be illustrated. These components can use 2 or more types. In addition to these components, consumption ratios of unsaturated polybasic acids such as maleic acid, fumaric acid and itaconic acid, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p- (β-hydroxyethoxy) benzoic acid can be used. The proportion of the unsaturated polybasic acid component and the hydroxycarboxylic acid component is at most 10 mol%, preferably at most 5 mol%. Moreover, as a polyol component, ethylene glycol, 1, 4- butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1, 6- hexanediol, 1, 4- cyclohexane dimethanol, xylylene glycol, dimethyrol propionic acid , Glycerin, trimetholpropane, poly (ethylene oxy) glycol, poly (tetramethyleneoxy) glycol and the like can be exemplified. These can use 2 or more types. Among these, by selecting the copolyester containing isophthalic acid and diethylene glycol, since the adhesiveness of an interface can be optimized and solvent resistance can be made, and also the film collectability at the time of film forming is excellent, it can use preferably. have. The amount of isophthalic acid as the polymerization component is preferably from 65 to 95 mol%, more preferably from 70 to 95 mol%. Moreover, as for the amount of diethylene glycol as the said polymerization component, 50-95 mol% is preferable, More preferably, it is 60-90 mol%. Although well-known dicarboxylic acid and diol can be used as another copolymerization component, it is not limited to them. The range of the preferable glass transition point of the said polymeric polyester is 0-60 degreeC, More preferably, it is 10-45 degreeC.

On the other hand, the constituent components of the copolymerized acrylic resin are acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, soda acrylate, ammonium acrylate, 2-hydroxyethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate and methacrylate. Butyl acid, sodium methacrylate, ammonium methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, acryl methacrylate, sodium vinyl sulfonate, sodium methacrylate sulfonate, sodium styrene sulfonate, acrylamide, Methacrylamide, N-metholol methacrylamide, etc. can be illustrated. These monomers can also be used together with other unsaturated monomers, such as styrene, vinyl acetate, acrylonitrile, methacrylonitrile, a vinyl chloride, vinylidene chloride, and divinylbenzene, for example.

As the acrylic copolymer, a modified acrylic copolymer, for example, the acrylic copolymer may be used as a block polymer or a graft polymer modified with polyester, polyurethane, silicone, epoxy, phenol resin or the like.

As for content of the said vehicle material, 60-95 mass parts is preferable with respect to the total amount of resin which forms the layer (C) which has an antistatic agent. When the content is too small, the solvent resistance or interfacial adhesion with the polyester layer (A) or the polyester layer (B) may be inferior, and when too large, the antistatic property may be inferior.

Surfactant (R)

It is preferable to mix | blend surfactant (R) with the antistatic coating film in this invention in order to make the adhesiveness of a coating film and a polyester film strong, and to make the blocking resistance of an antistatic laminated film favorable. . As such surfactant (R), for example, an alkylene oxide homopolymer, an alkylene oxide copolymer, an aliphatic alcohol alkylene oxide adduct, a long chain aliphatic substituted phenol alkylene oxide addition polymer, a polyhydric alcohol aliphatic ester, a long chain Cationic or anionic surfactants such as nonionic surfactants such as aliphatic amide alcohols, compounds with quaternary ammonium salts, compounds with alkylpyridinium salts and compounds with sulfonates, and the like, and especially nonionic surfactants. Since the effect on the adhesiveness of a temporary coating film and a polyester film, and the blocking resistance of an antistatic polyester film is favorable, it is preferable.

Content of surfactant is 1-15 mass parts with respect to the total amount of resin which forms the layer (C) which has an antistatic agent, Preferably it is 3-10 mass parts. If this ratio is less than 1 part by mass, the wettability of the aqueous coating liquid to the polyester film may be insufficient. If it exceeds 15 parts by mass, the adhesion of the coating film to the polyester film is insufficient, or the blocking resistance is insufficient. There is.

[Production method]

Next, although the manufacturing method of the white polyester film of this invention is demonstrated, it is not limited to this example. Polymethylpentene as an incompatible thermoplastic resin, polyethyleneglycol, polybutylene terephthalate and polytetramethylene glycol copolymer as a low specific gravity agent are mixed with polyethylene terephthalate, and the mixture is sufficiently mixed and dried to obtain a temperature of 270 to 300 ° C. Feed to extruder A heated to temperature. Polyethylene terephthalate containing an optical stabilizer and, if necessary, an inorganic additive such as SiO ₂ is supplied to the extruder B by a conventional method, and the polymer of the polyester layer (B) is brought to both surface layers in a three-layered die of T die. You may laminate by the three-layered constitution of ester layer (B) / polyester layer (A) / polyester layer (B).

The molten sheet was tightly cooled and solidified by an electrostatic force on a drum cooled to a drum surface temperature of 10 to 60 ° C, guided to the roll group in which the unstretched film was heated to 80 to 120 ° C, and 2.0 to 5.0 times longitudinal stretching. And it cools by the roll group of 20-50 degreeC. Subsequently, the coating liquid which forms the layer (C) containing an antistatic agent is apply | coated by the bar coat system using a metalling bar, and after that, it guides to a tenter, holding both ends of the longitudinally stretched film with a clip, and is 90-140 degreeC The film is transversely stretched in the direction perpendicular to the length in the atmosphere heated by the furnace. Although the draw ratio is stretched 2.5-4.5 times in length and width, respectively, it is preferable that the area magnification (longitudinal draw ratio X transverse draw ratio) is 9-16 times. If the area ratio is less than 9 times, the whiteness of the film obtained becomes poor, on the contrary, if it exceeds 16 times, there is a tendency that cracking is easily observed at the time of stretching and the film forming property is poor. In order to impart planarity and dimensional stability of the biaxially stretched film in this way, heat setting is performed at 150 to 230 ° C. in a tenter, uniformly slow cooled, and then cooled to room temperature and wound up to obtain a white poly for liquid crystal display reflecting plate of the present invention. Obtain an ester film.

The white polyester film for liquid crystal display reflecting plates of this invention obtained in this way has the high glossiness of at least one surface, there is little diffuse reflection, and the fine bubble is formed in the inside of a film, and the high reflectivity is achieved, and the liquid crystal of the anti-prism type When used as a reflecting plate of a display, high luminance can be obtained. It is also excellent for UV light.

Moreover, the structure of the white polyester film for liquid crystal display reflecting plates of this invention is a laminated structure which used the polyester layer (A) and polyester layer (B) as mentioned above, and the said layer (A) has the said micro bubble It is preferable that it is a layer which contains both high reflectance and film forming property. Moreover, it is preferable that a film surface is a polyester layer (B), Inorganic particle and / or organic particle | grains are contained in polyester, and the total weight of a polyester layer (B) (layer which contains an inorganic particle and / or organic particle | grains) is carried out. 0.5 wt% or less, preferably 0.1 wt% or less, and more preferably 0.07 wt% or less of the layer is contained in order to improve mirror reflectivity. In addition, the reverse prism system has a structure in which the reflecting plate 12 of FIG. 1 is in close contact with the light guide plate 13, and it is easy to cause a problem that the inorganic particles fall off and cause damage to the light guide plate. When the amount of the particle added exceeds 0.5% by weight, it is easy to cause scratches due to the dropping of the particles, and therefore the amount of the particle added is preferably 0.5% by weight or less, and more preferably 0.1% by weight or less.

[Measurement of Physical Properties and Evaluation of Effects]

The evaluation method of the physical property value of this invention and the evaluation method of an effect are as follows.

(1) Film thickness (each layer total thickness)

The film sample was measured with a ten-point thickness with a calibrated digital micrometer (M-30, manufactured by Sony Precision Technology), and the average value was made into the thickness of the film.

(2) the thickness of each layer

The film was sampled at 5 mm x 1 cm, and it cut | disconnected in the cross section direction in ice using the microtome. From the cross-sectional photograph which observed the cross section of the polyester layer (A) and the polyester layer (B) of the sample cut | disconnected using the transmission electron microscope HU-12 type (made by Hitachi Seisakusho Co., Ltd.), and expanded by 250 times. Lamination thickness was calculated | required.

(3) average particle diameter

(Inorganic particles)

100 particles were randomly selected with respect to the particle | grains before adding to a resin (film) about the magnification 10000 times using the Hitachi Seisakusho S-2100A type | mold scanning electron microscope. Particle diameters were measured for 100 particles, and the average particle diameter was obtained from the remaining 90 except for five from the largest and the smallest from the largest (the particle is not spherical). Approximated to the ellipse close to the shape, and obtained by (long diameter + short diameter) / 2 of the ellipse).

(Emergency resin)

The film sample is cut out into squares and fixed in embedding capsules, and then embedded in epoxy resin. The embedded sample was a 50 nm-thick thin film slice having a cross-section parallel to the film forming direction with a microtome (ULTRACUT-S), and observed at a magnification of 10000 times using a Hitachi Seisakusho S-2100A type scanning electron microscope. Photographed, and randomly selected 100 particles. Particle diameters were measured for 100 particles, and the average particle diameter was obtained from the remaining 90 except for five from the largest and the smallest from the largest (the particle is not spherical). The shape was approximated to an ellipse close to the shape, and found as (long diameter + short diameter) / 2 of the ellipse).

(4) film forming stability

It evaluated by the following reference | standard whether it can form into a film stably.

(Circle): It can form into a film stably for 1 hour or more.

X: Break | rupture generate | occur | produces within 1 hour, and stable film forming cannot be performed.

(5) coating film adhesion

The film after film forming was cut out to the size of 0.5m * 0.5m, the coating surface was visually observed, and the number of the oval defects peculiar to application | coating missing was counted.

○: The number of defects is 30 or less

×: 30 or more defects

(6) reflectance

An integrating sphere was attached to a spectrophotometer (U-3310) manufactured by Hitachi High Technologies, and the reflectance when the standard white plate (aluminum oxide) was 100% was measured over 400 to 700 nm. The reflectance is read at intervals of 5 nm from the obtained chart, and the average value is calculated to be the average reflectance.

(7) Surface Specific Resistance (Antistatic)

The sample was left to stand for 1 day in an atmosphere of 23 ° C. × 50% RH using a Kawaguchi Denki Seisakusho surface resistivity measuring instrument (MMAII-17A). After leaving for 1 minute by applying a voltage of 500 V, the surface specific resistance of the coated surface was measured. The type of the electrode used here is made by the same company (model number P-618), and is a concentric circular electrode having an outer diameter of 90 mm for the main electrode and an inner diameter of 45 mm for the counter electrode.

(8) surface roughness

Surface average roughness (Ra) and 10-point average surface roughness (Rz) were measured using Kosaka Kenkyu Sho, a stylus type surface roughness meter (model number: SE-3FA). The conditions were as follows and were made into the value with the average value of 5 measurements.

Tip tip radius: 0.5㎛

Probe load: 5 mg

Measurement length: 0.8 mm

Cut-off value: 0.08 mm

(9) dust adhesion (ash test)

The white polyester film cut into A4 size was humidified for 24 hours in 23 degreeC and the measurement atmosphere of 50% RH. The moist film surface was rubbed with a friction cloth (100% wool) for 10 round trips. The film was immediately brought into close contact with a 1.5 g of tobacco material preliminarily dried at 70 ° C. for 1 hour on a desk spread in a range of 10 cm × 10 cm. The attachment of cigarette ash was visually determined. △ or more is a pass.

(Circle): It does not adhere even if a film makes contact with a ash.

(Triangle | delta): It adheres when a film makes contact with a ash.

X: It adheres only by bringing a film close to the ash.

10 shades

Lab color tone was measured in the reflection mode in C light and 2 degrees field of view using the Suga Shigenki colormeter SM-6.

(11) UV irradiation test

The light resistance was evaluated by irradiating an ultraviolet-ray to a sample using the ISUSAKI Denki Eye Super UV Tester (model number: SUV-W131), and measuring the hue b value before and behind irradiation. In the present invention, the irradiation UV amount was 100 mW / cm 2 at a wavelength of 365 nm, and the UV irradiation time was 4 hours.

(12) specific gravity

The film is accurately sampled at 10 cm x 10 cm and accurately weighed to 0.1 mg units with an electronic balance (AC100 manufactured by Mettler). After taking out the weighed sample, the total thickness of each layer of the film is measured using a static pressure thickness meter, and substituted into the following formula to calculate specific gravity.

Specific gravity = (weighing value (g)) / (total thickness (m) of each layer) x 100.

(13) Brightness (luminance) of the screen

As shown in FIG. 1, the reflecting film 12 of the 4 lamp type backlight of Samson Corporation liquid crystal monitor 750B was changed into the reflecting film produced by each Example and the comparative example, and it measured. Luminance measurement uses 100V of home power supply and applies voltage by changing ON / OFF switch. We waited for uniformity and constant brightness of cold cathode tube. Thereafter, luminance was measured at a measurement distance of 500 mm with luminance meter 15 (BM-7fast manufactured by Topcon). The number of measurements is taken three times and the average value is taken. Relative evaluation which used Toray's reflective film E6SL (250 micrometers in total thickness of each film) as 100 was used for evaluation of the value of luminance.

Example

The present invention will be described based on examples.

EXAMPLES 1-19

The raw material shown below for the raw material polymer of the polyester layer (A) was mixed by the compounding ratio shown in Table 1. It produced by setting extrusion temperature to 320 degreeC, and supplying to extruder A heated at 270-300 degreeC.

Polyethylene terephthalate chip (F20S made by Toray Corporation)

Copolymer of polyethylene glycol, polybutylene terephthalate with a molecular weight of 4000, and polytetramethylene glycol ("Hytrel" manufactured by Toray DuPont)

Copolymer obtained by copolymerizing 10 mol% of isophthalic acid and 5 mol% of polyethylene glycol in polyethylene terephthalate (T794M manufactured by Toray Corporation)

Polymethylpentene (Mitsui Kagaku Co., Ltd. product TPX820)

Silica particles having an average particle diameter of Table 1

Polyethylene naphthalate (manufactured by Aldrich, d = 1.328, m.p. 250-290 ° C.)

On the other hand, a mixture of any one of the light stabilizers a to d listed below, silica particles having an average particle diameter of 3.2 μm, and titanium dioxide having an average particle diameter of 0.2 μm was mixed on a chip of polyethylene terephthalate at a ratio shown in Table 2. After vacuum drying at 180 degreeC for 3 hours, the raw material polymer of the polyester layer (B) was produced by supplying to the extruder B heated at 280 degreeC.

a: malonic acid ester light stabilizer ("B-CAP" made by Clariant Japan Co., Ltd.)

b: malonic ester-based light stabilizer ("PR-25" manufactured by Clariant Japan Co., Ltd.)

c: triazine light stabilizer ("CGX006" made by Chiba Specialty Chemicals)

d: Benzophenone light stabilizer ("Adecasta LA-51" by Asahi Denka Co., Ltd.).

The composition of the coating liquid which forms the layer (C) containing an antistatic agent is as follows. Nihon Carbide Co., Ltd. Nicarzol RX-7013ED (acrylic acid polyester resin emulsion: described as X in Table 3) and Nihon NSC coating agent Verser YE-910 (polyester sulfonate lithium salt antistatic agent: Y in Table 3 The mixture of RX-7013ED and YE-910 in the ratio shown in Table 3 in solid content mass ratio was diluted with water, and produced by adding 0.1% of total liquid ratio RY-2 made from Koga Kagaku. In addition, the coating layer (C) was formed in one surface of the film, and said surface was called A surface.

The raw material polymer of the polyester layer (A) and the polyester layer (B) was laminated | stacked through the lamination apparatus so that layer structure and layer thickness might be as Table 1, and it shape | molded in the sheet form with T-die. The unstretched film obtained by cooling and solidifying the film in a cooling drum having a surface temperature of 25 ° C was guided to seven roll groups whose heating temperature was adjusted to 85 to 98 ° C, followed by longitudinal stretching of 3.4 times in the longitudinal direction, and at a roll group of 25 ° C. Cooled. Subsequently, the coating liquid which forms the layer (C) containing an antistatic agent was apply | coated by the bar coat system of metal ring bar, and C layer was formed. Both ends of the obtained coating film were guided to the tenter while holding the clip with a clip, and transversely stretched 3.6 times in the direction perpendicular to the length in the atmosphere heated at 130 ° C. Then, the heat setting of 190 degreeC was performed in the tenter, and it cooled slowly evenly, and after cooling to room temperature, the film of odor thickness 250 micrometers was obtained. Physical properties of the obtained film as a reflecting plate substrate were as shown in Table 9. In either case, antistatic properties were good for at least one film surface.

In addition, the kind and content of a light stabilizer are as showing in Table 7. In addition, silica, barium sulfate, titanium dioxide, and polymethylpentene contained in the film were all in the film, and formed fine bubbles.

[Examples 20 to 52]

The raw materials of the polyester layer (A) and the polyester layer (B) shown in Tables 4 and 5 were fed to two extruders heated at 280 ° C, respectively, and the multilayer feed block so that the layer structure and the layer thickness were as shown in Table 4. It joined together using the apparatus and was shape | molded from the dice into the sheet form, maintaining the lamination | stacking state. Moreover, the unstretched film which cooled and solidified this sheet | seat by the cooling drum of 25 degreeC of surface temperature was heated at 90 degreeC, it extended | stretched 2.9 times in the longitudinal direction (vertical direction), and cooled in 25 degreeC roll group. On one side or both sides of this uniaxial stretched film, the aqueous coating liquid shown below was apply | coated by the microgravure coating method by the application amount of 4 g / m <2> (wet).

Here, the copolyester used in Tables 4 and 5 refers to a polyester copolymerized with a dicarboxylic acid component or a diol component in the copolymerization amount (mol%) described in the table. In the table, IPA represents isophthalic acid (dicarboxylic acid component), and CHDM represents cyclohexanedimethanol (diol component).

In addition, the aqueous coating liquid has an acid component of terephthalic acid [67 mol%], isophthalic acid [27 mol%] and 5-Nasulfoisophthalic acid [6 mol%], and a glycol component of ethylene glycol [30 mol%], diethylene. Copolyester (Tg = 51 ° C.) (described in q in Table 6) consisting of glycol [40 mol%] and neopentyl glycol [30 mol%] is used as the vehicle material (Q), and polystyrene sulfonic acid Na (chemistat SA-9, manufactured by Sanyokasei) (described as p-1 in Table 6), or polythiophene water dispersion (Byteron P, made by Bayer Corporation) (described as p-2 in Table 6) as antistatic agent (P) A polyoxyethylene lauryl ether (described in r in Table 6) was used as a surfactant (R), and a 10% by weight aqueous solution having a solid content composition containing each component at a ratio shown in Table 6 was used. In addition, when forming an application layer (C) in one surface of a film, the said surface was called A surface. In that case, when a film structure was a 2-layered structure of A / B, the application layer (C) was formed in the surface of the polyester layer (A), and the said surface was called A surface. When forming application layer (C) on both surfaces of a film, it was A surface and B surface, respectively.

Subsequently, the coating liquid was stretched at a magnification of 3.7 in a direction perpendicular to the length (horizontal direction) in an atmosphere heated at 120 ° C by guiding the tenter while keeping both ends of the dry film with a clip. Then, heat setting was performed at 210 degreeC in the tenter, it cooled to room temperature, and the biaxially stretched film was obtained. Physical properties of the obtained film as a reflecting plate substrate were as in Table 10. In either case, the antistatic property was good for at least one film surface.

In addition, the kind and content of a light stabilizer are as showing in Table 8. In addition, all the silica, barium sulfate, titanium dioxide, and polymethyl pentene contained in the film formed the micro bubble in the film.

[Comparative Examples 1, 2, 3]

It formed into a film by the method and conditions similar to Example 1 using the raw material of Tables 1-3. Since the light stabilizer was not added, durability became inferior.

[Comparative Examples 4 and 5]

It formed into a film by the method and conditions similar to Example 1 using the raw material of Tables 1-3. Since the light stabilizer was not added, durability was inferior and reflectance was low because there was little quantity of incompatible thermoplastic resin.

Comparative Example 6

It formed into a film by the method and conditions similar to Example 20 using the raw material of Tables 4-6. Since the particle diameter of titanium dioxide which is an inorganic particle is small, a fine bubble is not produced | generated and it became a low reflectance.

[Comparative Examples 7, 8]

It formed into a film by the method and conditions similar to Example 20 using the raw material of Tables 4-6. Since the particle diameter of titanium dioxide which is an inorganic particle is large, a bubble becomes large and as a result, the reflectance became low.

Comparative Example 9

It formed into a film by the method and conditions similar to Example 20 using the raw material of Tables 4-6. Since the content of the inorganic particles was small and the overall thickness was thin, there were few bubbles, and as a result, the reflectance was low.

Comparative Example 10

It formed into a film by the method and conditions similar to Example 20 using the raw material of Tables 4-6. Although content of an inorganic particle is sufficient, since the total thickness is thin, there are few bubbles, and as a result, it became low reflectance.

[Comparative Examples 11 and 12]

It formed into a film by the method and conditions similar to Example 20 using the raw material of Tables 4-6, However, since the ratio of copolymerization was low, the film | membrane in film forming was frequent and a sample could not be prepared.

Comparative Example 13

It formed into a film by the method and conditions similar to Example 20 using the raw material of Tables 4-6. Since the light stabilizer was not added, durability became inferior.

This invention is used suitably as a base material for reflective films which require light resistance and vibration damping performance.

Claims (17)

The polyester film which has a fine bubble contains an optical stabilizer, and the average reflectance of at least one surface of the said film is 97% or more, The white polyester film for liquid crystal display reflecting plates characterized by the above-mentioned. The liquid crystal display reflecting plate according to claim 1, wherein the polyester film has a structure in which a polyester layer (B) containing an optical stabilizer is laminated on at least one surface of a polyester layer (A) having fine bubbles. White polyester film. The layer (C) containing an antistatic agent is coated on at least one surface of the polyester film, and the surface specific resistance value of the layer (C) is 1 × 10 ¹³ Ω / square or less. Polyester film for liquid crystal display reflectors. The white polyester film for liquid crystal display reflecting plate according to claim 1, wherein the center surface average roughness Ra of the surface of the polyester film is 0.1 or more and the ten point average roughness Rz is 1.0 or more. The content of the light stabilizer contained in the polyester film is 0.02% by weight or more and 20% by weight or less with respect to the total weight of the polyester film. The white polyester film for liquid crystal display reflecting plate according to claim 1, wherein the light stabilizer contained in the polyester film is a malonic acid ester light stabilizer. 2. The white polyester film for liquid crystal display reflecting plate according to claim 1, wherein the light stabilizer contained in the polyester film is 2,6-naphthalenedicarboxylic acid or a copolymer thereof. The polyester film of claim 1, wherein titanium dioxide particles are contained in the polyester film, and the content thereof is 1 wt% or more and 40 wt% or less with respect to the total weight of the polyester film. . The polyester film according to claim 1, wherein the polyester film contains particles having a mean particle size of 1.0 µm or more (hereinafter, large particle size), and the content thereof is 0.01% by weight or more and 5% by weight or less based on the total weight of the polyester film. The white polyester film for liquid crystal display reflectors characterized by the above-mentioned. 10. The polyester film for liquid crystal display reflector as claimed in claim 9, wherein the large particle size is a silica particle. 2. The white polyester film for liquid crystal display reflector as claimed in claim 1, wherein the polyester film contains polyester and an incompatible thermoplastic resin. 12. The thermoplastic resin incompatible with the polyester is polymethylpentene, and the average particle diameter in the polyester film is equal to or less than the average particle diameter of the large particle size, and with respect to the total weight of the polyester film. 5 weight% or more and 25 weight% or less are contained, The white polyester film for liquid crystal display reflectors. The specific gravity of the said polyester film is 0.5 or more and 1.2 or less, The white polyester film for liquid crystal display reflecting plates of Claim 11 characterized by the above-mentioned. 2. The white polyester film for liquid crystal display reflecting plate according to claim 1, wherein fine bubbles are formed when the polyester film contains inorganic particles. The inorganic particle contained in order to form the said fine bubble is barium sulfate, The average particle diameter of the said barium sulfate is 0.1 micrometer or more and 5.0 micrometers or less, The average particle diameter of a large particle size is the said. It contains 5 to 70 weight% with respect to the total weight of a polyester film, The white polyester film for liquid crystal display reflecting plates characterized by the above-mentioned. The specific gravity of the said polyester film is 1.2 or more and 1.4 or less, The white polyester film for liquid crystal display reflecting plates of Claim 14 characterized by the above-mentioned. The polyester film of Claim 2 whose deep layer part is the said polyester layer (A), the surface layer part of one or both sides is the said polyester layer (B), The white polyester film for liquid crystal display reflecting plates characterized by the above-mentioned.

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