JP2009202463A - Easily-adhesive polyester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily-adhesive polyester film which decreases interference irregularity owing to reflection of external light when a hard coat layer is arranged, the adhesion of which to the hard coat layer can be sufficiently kept at high temperature/high humidity and which can be suitably used in optical applications such as various display constitution and display members and a film for producing the display member. <P>SOLUTION: The easily-adhesive polyester film has a coating layer on at least one side of a polyester film stretched uniaxially at the least. The coating layer contains a polyester resin which substantially comprises 2,6-naphthalene dicarboxylic acid and an aromatic dicarboxylic acid having an anionic group as dicarboxylic acid components, and substantially comprises the ethylene oxide adduct of bisphenol A as a glycol component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an easily adhesive polyester film. For example, the present invention relates to a liquid crystal display (hereinafter abbreviated as LCD), a plasma display panel (hereinafter abbreviated as PDP), and organic electroluminescence (hereinafter abbreviated as organic EL). ) And the like, and an easily adhesive polyester film suitable for optical applications such as a film for production thereof.

  Conventionally, optical films based on polyester films have been used for various optical applications including display members such as LCDs, PDPs, and organic ELs, and films for manufacturing the same. These optical films are required to have excellent transparency and visibility.

  These optical films are used by laminating surface functional layers such as a hard coat layer and an antireflection layer on a plastic film. As the plastic film, a transparent polyester film is generally used, and in order to improve the adhesion between the base polyester film and the surface functional layer such as a hard coat layer, an easy-adhesive coating is used as an intermediate layer between them. In general, a layer is provided.

  As an antireflection film, generally, a high-refractive index layer and a low-refractive index layer are alternately laminated as a surface functional layer to prevent reflection of external light by utilizing a light interference phenomenon.

  In recent years, applications such as display members such as LCDs and PDPs are required to have larger screens, higher image quality, and higher quality, and accordingly, the level of demand for suppressing interference unevenness particularly under fluorescent lamps has increased. ing. In addition, fluorescent lamps are mainly in the three-wavelength form for daylight color reproducibility, and interference unevenness is more conspicuous. The occurrence of uneven interference in the image display device is particularly noticeable in a dark state where an image is not displayed, and as a result, the image display device itself gives a cheap impression and is hated. On the other hand, in order to achieve cost reduction, there is an increasing demand for simplification of the antireflection layer. Therefore, the importance of optical design of the coating layer laminated on the polyester film is increasing.

  In order to improve the interference unevenness of the hard coat film, a curable resin for forming a hard coat layer having a refractive index close to that of a base polyester film (for example, 1.64 for a polyethylene terephthalate film) has also been developed. However, when the above-mentioned polyester film easy-adhesion layer has a low refractive index, the difference between the refractive index of the easy-adhesion layer and the refractive index of the polyester film base material or the hard coat layer is increased. It is considered that the interference unevenness occurs. Therefore, the easy-adhesion layer of the base film improves the adhesion with the hard coat layer and is designed so that the refractive index is intermediate between the refractive index of the hard coat and the refractive index of the polyester film. It is an improvement measure.

  As an improvement of the easy-adhesion layer, the present inventors have included a compound having a condensed polycyclic aromatic in the easy-adhesion layer (Patent Document 1) and a compound containing a bisphenol A structure. (Patent Document 2) is proposed. These improvements have a certain effect on the adhesion with the hard coat and the suppression of uneven interference.

  However, with regard to the adhesion between the base film as the image display member and the hard coat layer, the required level is increasing, not only in the normal environment, but also in the environment of high temperature and high humidity. It is required to maintain sufficient adhesion. In response to these demands, there have been situations where the conventional improvements are insufficient, and further improvements have been demanded.

JP 2006-175628 A JP 2007-130958 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that when the hard coat layer is provided, interference unevenness due to reflection of external light is reduced, and the hard coat is sufficient even under high temperature and high humidity. It is in providing the easily-adhesive polyester film which can maintain suitably the adhesiveness and can be utilized suitably for optical uses, such as various display structure display members and its manufacturing film.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the use of a laminated polyester film having a specific configuration can solve the above-mentioned problems, and have completed the present invention.

  That is, at least one side of a polyester film stretched at least in a uniaxial direction is substantially composed of 2,6-naphthalenedicarboxylic acid as a dicarboxylic acid component and an aromatic dicarboxylic acid having an anionic group, and substantially as a glycol component. And a coating layer containing a polyester resin composed of an ethylene oxide adduct of bisphenol A.

Hereinafter, the present invention will be described in more detail.
In the easily adhesive polyester film of the present invention, at least one side of the polyester film stretched at least in a uniaxial direction is substantially 2,6-naphthalenedicarboxylic acid and an aromatic dicarboxylic acid having an anionic group as a dicarboxylic acid component. It is necessary to have a coating layer containing a polyester resin substantially composed of an ethylene oxide adduct of bisphenol A as a glycol component.

  The polyester resin used for the coating layer is substantially composed of 2,6-naphthalenedicarboxylic acid and an aromatic dicarboxylic acid having an anionic group as its dicarboxylic acid component. The term “substantially” as used herein means that the dicarboxylic acid component is composed only of 2,6-naphthalenedicarboxylic acid and an aromatic dicarboxylic acid having an anionic group. Including by-product or the like, other dicarboxylic acids are contained in an amount of 5 mol% or less, preferably 1 mol% or less.

  The anionic group of the aromatic dicarboxylic acid having an anionic group of the present invention is a sulfonic acid group, a carboxylic acid group, or a phosphoric acid group, and an aromatic dicarboxylic acid having any of these as a functional group is an essential component. To do. Examples of the aromatic dicarboxylic acid whose anionic group is a sulfonic acid group include sulfonylisophthalic acid, sulfonylphthalic acid, sulfonylterephthalic acid, and sulfonyl-2,6-naphthalenedicarboxylic acid. Examples of the aromatic dicarboxylic acid whose anionic group is a carboxylic acid group include trimellitic acid and pyromellitic acid. When the anionic group is a phosphate group, phosphonyl isophthalic acid and the like can be mentioned. Among these aromatic dicarboxylic acids, when the anionic group is a sulfonic acid group, it is suitable when a polyester resin containing the anionic group is used as an aqueous dispersion as described later, and the aqueous dispersion is also stable. It is preferable in a certain point. At this time, the counter ion of the anionic group is preferably an alkali metal salt such as sodium or potassium, an ammonium salt, or a quaternary amine salt.

  The ratio of the aromatic dicarboxylic acid having an anionic group is not particularly limited, but is preferably 0.1 to 10 mol%, more preferably 1 to 8 mol%, based on the dicarboxylic acid component. is there. When the ratio of the aromatic dicarboxylic acid having an anionic group is within this range, the polyester resin used in the coating layer is easily formed into an aqueous dispersion as described later, and at the same time, the hygroscopicity of the polyester resin is likely to cause blocking. It is preferable in that it does not become so high.

  The polyester resin used for the coating layer needs to have a glycol component substantially composed of an ethylene oxide adduct of bisphenol A. The term “substantially” as used herein means that the glycol component is composed only of an ethylene oxide adduct of bisphenol A. By mixing impurities or by-products during the reaction, It is also included to contain 5 mol% or less, preferably 1 mol% or less.

  The structural formula of the ethylene oxide adduct of bisphenol A is shown by the following formula.

  However, the number of additions n and m of ethylene oxide is preferably 1 or 2, and the ethylene oxide adduct wherein n = m = 1 is 50 mol% or more of the total ethylene oxide adduct of bisphenol A, Is 80 mol% or more, the coating layer containing this polyester resin is preferable because the adhesiveness under high temperature and high humidity becomes better.

  In particular, in the present invention, the polyester resin in the coating layer is substantially free of phthalic aromatic dicarboxylic acid having no anionic group, such as terephthalic acid and isophthalic acid, which are commonly used as a dicarboxylic acid component. . Thereby, the polyester resin in the coating layer can maintain the initial adhesiveness for a long period of time even under high temperature and high humidity. The reason for this is not clear, but when the polyester resin in the coating layer contains terephthalic acid or isophthalic acid, the polyester resin deteriorates due to hydrolysis at high temperatures and high humidity. The polyester resin used in the present invention is composed of only 2,6-naphthalenedicarboxylic acid and an aromatic dicarboxylic acid having an anionic group, so that degradation due to hydrolysis is much less. It is estimated that good adhesion can be maintained for a long time even under high humidity. In addition, since 2,6-naphthalenedicarboxylic acid contains a large amount (for example, 90 mol% or more) of the dicarboxylic acid component, the refractive index of the polyester resin itself can be increased. It is considered that the absolute reflectance is maintained high, and it becomes difficult to generate interference unevenness in the hard coat layer when, for example, a hard coat layer is laminated thereon.

  In the present invention, the glycol component of the polyester resin in the coating layer is substantially free of ethylene glycol or the like that is usually used, and uses only the ethylene oxide adduct of bisphenol A. Thereby, the adhesiveness of the coating layer containing this polyester resin improves. The reason for this is not clear, but the polyester of ethylene glycol and aromatic dicarboxylic acid has crystallinity (considering that microscopic crystals exist even in the case of copolymerization), but as glycol It is presumed that the polyester using only the ethylene oxide adduct of bisphenol A is completely amorphous and therefore has higher adhesion.

  The polyester resin used for the coating layer of the present invention can be produced by conventional polyester production techniques. For example, a lower alcohol ester such as 2,6-naphthalenedicarboxylic acid or methyl ester thereof, a lower alcohol ester such as an aromatic dicarboxylic acid having a salt of an anionic group or methyl ester thereof, and bisphenol It can be produced by reacting with the ethylene oxide adduct of A to form an oligomer and then polycondensing under vacuum to obtain a polyester having a predetermined degree of polymerization. At that time, a catalyst for promoting the reaction, for example, a known esterification or transesterification catalyst or a polymerization catalyst can be used, and various additives such as a stabilizer such as an antioxidant can also be added.

  The polyester resin used in the coating layer of the present invention is preferably an aqueous dispersion containing water as a main medium, and is applied to the polyester film as an aqueous coating agent containing this by in-line coating or the like described later. For this purpose, it is necessary to use a polyester resin as an aqueous dispersion, and conventionally known methods can be applied to this method. For example, a polyester resin and a water-soluble organic solvent are first mixed and dissolved while heating at a temperature not higher than the boiling point of the water-soluble organic solvent. While strongly stirring this solution, water is added to precipitate the polyester resin as fine particles to form an aqueous dispersion. Moreover, it can also be set as an aqueous dispersion also by the method of dripping the said solution to the water under stirring. The obtained aqueous dispersion can be further distilled under normal pressure, preferably under reduced pressure, and the water-soluble organic solvent can be distilled off to obtain the desired aqueous dispersion. In this case, depending on the aqueous organic solvent to be used, it is distilled off as an azeotrope with water, so that it is possible to add more than a predetermined amount of water in advance.

  Water-soluble organic solvents used above include glycols such as ethylene glycol and propylene glycol, glycol derivatives such as propylene glycol monomethyl ether, methyl cellosolve, ethyl cellosolve, n-butyl cellosolve, and t-butyl cellosolve, and dioxane. In addition, one kind or two or more kinds can be used in combination as appropriate from ethers such as tetrahydrofuran and ketones such as methyl ethyl ketone. In particular, propylene glycol monomethyl ether, methyl cellosolve, ethyl cellosolve, n-butyl cellosolve, t-butyl cellosolve and the like are preferable from the viewpoint of dispersibility in water and applicability to a film. In this case, these water-soluble organic solvents may remain in a proportion of 20% by weight or less as a part of the aqueous medium without being completely removed from the aqueous dispersion.

  In the coating layer of the easily adhesive polyester film of the present invention, in addition to the above-mentioned polyester resin, other resin components can be contained within a range that does not affect the effects of the present invention. As another resin component, for example, an acrylic resin, a polyurethane resin, an epoxy resin, or the like, a water-soluble or water-dispersible resin can be mixed with the aqueous dispersion of the polyester resin and applied to the polyester film.

  Moreover, the coating layer of the easily adhesive polyester film of the present invention can contain a crosslinking agent component in addition to the above polyester resin. As the crosslinking agent component, melamine crosslinking agent, epoxy crosslinking agent, oxazoline crosslinking agent, aziridine crosslinking agent, isocyanate crosslinking agent, titanium coupling agent and the like can be used. Among these crosslinking agents, The melamine-based cross-linking agent has the effect of increasing the absolute reflectance of the surface of the easy-adhesion layer when used in combination with the above-mentioned polyester resin. And by forming a crosslinked structure in the coating layer, it can be preferably used in that it can further improve the durability of the adhesiveness at high temperature and high humidity, and can impart solvent resistance. In this case, the ratio of melamine to polyester in the coating layer can be selected in the range of 1:99 to 70:30, preferably 5:95 to 60:40.

  In addition, organic lubricants such as fine particles and wax, antioxidants, antistatic agents, surfactants, and the like can be added to the coating layer as long as the effects of the present invention are not affected. In addition, about each composition in a coating layer, it can measure by TOF-SIMS, for example.

In the easily-adhesive polyester film of the present invention, it is necessary to have the above-mentioned coating layer on at least one side of the film. The coating amount of this coating layer is usually 0.005 to 1 g as a final coating film. / M ² , preferably in the range of 0.01 to 0.5 g / m ² . If the coating amount is less than 0.005 g / m ^2, the adhesion is insufficient, whereas when applied beyond 1 g / m ² is no longer easy adhesion effect is saturated.

  In the easy-adhesive polyester film of the present invention, the absolute reflectance of the surface of the coating layer is preferably 4.7% or more, more preferably 5.0% or more, at any wavelength of 350 to 800 nm, and the upper limit. Should be 6.0. In addition, when the wavelength of light is drawn on the horizontal axis and the reflectance is drawn on the vertical axis, it is preferable to adjust the coating thickness of the coating layer so that the absolute reflectance has a minimum value in the range of 600 to 750 nm. With such an absolute reflectance on the surface of the coating layer, interference unevenness that can be visually recognized when a hard coat layer is laminated on the surface of the coating layer can be extremely reduced.

  The polyester film constituting the easy-adhesive polyester film in the present invention may have a single layer structure or a laminated structure, and may have four layers or two layers or three layers unless the gist of the present invention is exceeded. It may be a multilayer having more than that, and is not particularly limited.

  The polyester constituting the base film used in the present invention may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. In particular, polyethylene terephthalate is preferable because it has a good balance between cost and performance. On the other hand, the dicarboxylic acid component of the copolyester includes isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxybenzoic acid, etc.), etc. 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexane dimethanol, neopentyl glycol, is mentioned. Among these, it is preferable that the film is composed of polyester in which 60 mol% or more, preferably 80 mol% or more is an ethylene terephthalate unit.

  In the base film of the present invention, particles can be blended mainly for the purpose of imparting easy slipperiness. The type of particles to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness, and specific examples include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, Examples of the particles include kaolin, aluminum oxide, and titanium oxide. Further, the heat-resistant organic particles described in JP-B-59-521, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-5 micrometers normally, Preferably it is the range of 0.01-3 micrometers. When the average particle diameter is less than 0.01 μm, there are problems such as easy aggregation of particles and insufficient slipperiness, while when it exceeds 5 μm, In some cases, the height of the generated protrusion becomes large, and harmful effects may occur as a coarse protrusion.

  Furthermore, the particle content in the polyester of the base film is usually 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the particle content is less than 0.001% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 5% by weight, the transparency of the film is insufficient. There is.

  The method for adding particles to the polyester of the base film is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage of producing the polyester constituting each layer, but it is preferably added after completion of esterification or transesterification.

  Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

  In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the base film in the present invention as necessary.

  Although the thickness of the polyester film in this invention will not be specifically limited if it is a range which can be formed into a film as a film, Usually, it is 5-250 micrometers, Preferably it is the range of 10-200 micrometers.

  Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all. That is, the above-described polyester film raw material is used and dried and then melt-extruded, or melt-extruded while degassing moisture with a vented extruder. In this way, the molten sheet extruded from the die is cooled and solidified with a cooling roll to obtain an unstretched sheet, but at this time, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotating cooling drum, An electrostatic application adhesion method and / or a liquid application adhesion method are preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. For this stretching, either the sequential biaxial stretching method or the simultaneous biaxial stretching method can be selected. In the case of the sequential biaxial stretching method, first, the unstretched sheet is stretched in the longitudinal direction by a roll-type stretching machine or the like. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. The in-line coating described later is preferably performed at this stage. Next, the film is stretched in the width direction using a tenter. In that case, the stretching temperature is usually 70 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a biaxially oriented film. In the above-described stretching, a method in which stretching in the longitudinal direction, the transverse direction, or both is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  In the case of the simultaneous biaxial stretching method, first, inline coating described later is performed on the unstretched sheet. Next, the film is stretched and oriented in the machine direction and the width direction at the same time in a state of temperature control usually at 70 to 120 ° C., preferably 80 to 110 ° C. The draw ratio is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be employed.

  The above-mentioned in-line coating is a production method in which a coating liquid is applied and dried on the film surface and then stretched in at least one direction during the stretching process of the polyester film. In the manufacturing method by in-line coating, when a coating layer is provided on a polyester film, it has the efficiency which enables application | coating simultaneously with extending | stretching. At the same time, since the coating layer is stretched simultaneously with the film and heat-set, the adhesion between the coating layer and the film is increased, and the coating layer can be processed at a high temperature of, for example, 200 ° C. or more, so that the thermosetting reaction is sufficiently Therefore, it is possible to produce a film suitable as an easily adhesive polyester film. The coating layer in the present invention can be provided on the polyester film by the above-mentioned in-line coating, or a so-called off-line coating applied on the film once manufactured outside the film forming line may be employed. Can also be used together.

  In the present invention, the coating method for forming the coating layer on the polyester film may be a conventionally known coating method such as reverse gravure coating, direct gravure coating roll coating, die coating, bar coating, curtain coating and the like. Regarding the coating method, there is a description example in “Coating Method” published by Yoji Harasaki in 1979.

  In the present invention, the drying and curing conditions for forming the coating layer on the polyester film are not particularly limited. For example, when the coating layer is provided by off-line coating, it is usually 3 to 80 to 200 ° C. Drying and thermosetting are preferably performed for 40 seconds, preferably at 100 to 180 ° C. for 3 to 40 seconds.

  On the other hand, when the coating layer is provided by in-line coating, heat treatment is usually performed at 170 to 250 ° C. for 3 to 30 seconds as a guide.

  Regardless of offline coating or in-line coating, the polyester film surface to which the coating layer is applied may be subjected to corona treatment and / or plasma treatment in advance as necessary.

  The easy-adhesive polyester film of the present invention requires that the above-mentioned coating layer is laminated on at least one side of the polyester film as a base material, but when the above-mentioned coating layer is laminated only on one side, It is possible to provide some coating layer on the opposite surface. This coating layer has characteristics such as easy adhesion, easy slipping, antistatic properties, and releasability as functions. These application layers can be provided by applying the above-mentioned in-line coating or off-line coating or a combination of both.

  According to the easy-adhesive polyester film of the present invention, when a hard coat layer is provided, interference unevenness due to reflection of external light is reduced, the adhesive property is excellent, and the adhesive property to a hard coat is sufficient even under wet heat conditions. Can be maintained. For this reason, it can utilize suitably for various optical uses, such as various display structure display members and its film for manufacture, The industrial value is high.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. In the description of the examples, “parts” means parts by weight unless otherwise specified. The measurement method and evaluation method used in the present invention are as follows.

(1) Measurement of intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. It was dissolved and measured at 30 ° C.

(2) Measurement of average particle diameter (d50: μm) 50% of integration (weight basis) in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) The value was defined as the average particle size.

(3) Method for measuring absolute reflectance of coating layer surface In advance, a black tape (vinyl tape VT-50 manufactured by Nichiban Co., Ltd.) is pasted on the surface opposite to the surface where the absolute reflectance of the coating layer of the polyester film is measured. Using a spectrophotometer (with UV-3100PC type integrating sphere manufactured by Shimadzu Corporation), coating was performed under conditions of an incident angle of 5 °, a wavelength range of 350 to 800 nm, a sampling pitch of 1 nm, a slit width of 2 nm, and a low scanning speed. The absolute reflectance of the layer surface was measured. The minimum value of the absolute reflectivity was obtained by drawing a graph of a curve with the wavelength of light on the horizontal axis and the reflectivity on the vertical axis, and reading the wavelength of this minimum value.

(4) Initial adhesiveness measuring method On the surface of the coating layer of the polyester film, 100 parts of a curable coating material made by Nippon Synthetic Chemical Industry Co., Ltd., purple light (registered trademark) UT-4002 (refractive index 1.60), and pentaerythritol acrylate A mixed solution of 10 parts and 2 parts of IRGACURE 184 (trade name) manufactured by Ciba Specialty Chemicals as a curing agent was applied and dried at 80 ° C. for 5 minutes. Next, while running the film at a feed rate of 10 m / min, ultraviolet rays were irradiated using a mercury lamp under the conditions of irradiation energy of 120 W / cm and irradiation distance of 10 cm to obtain a film having a hard coat layer having a thickness of 5 μm. . Under an atmosphere of 23 ° C. and 50% RH, the film is subjected to cross cut (100 squares of 1 mm 2), and 18 mm wide tape (Cello Tape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) ) And abruptly peeled off at a peeling angle of 180 degrees, and the peeled surface was observed. If the peeled area was less than 5%, it was good (good), and if it was 5% or more but less than 20%, it was Δ If it was 20% or more and less than 50%, it was rated as x (insufficient), and if it was 50% or more, it was rated as xx (defective).

(5) Method for measuring resistance to moisture and heat resistance A film having a hard coat layer prepared by the method for measuring initial adhesion in (4) is treated in an oven at 85 ° C. and 85% RH for 300 hours in a constant temperature and humidity chamber. Then, after being allowed to stand in an atmosphere of 23 ° C. and 50% RH for 24 hours, the evaluation was performed in the same manner as in the method (4) for measuring the initial adhesiveness.

(6) Evaluation method of antireflection ability The film having the hard coat layer prepared by the method for measuring the initial adhesion in (4) is visually observed for interference unevenness under a three-wavelength fluorescent lamp. ◯ when almost unseen, △ when the interference non-uniformity can be seen depending on how light is reflected, and x when the non-uniform interference appears entirely.

  The polyester for a film base used in Examples and Comparative Examples is prepared as follows.

<Manufacture of polyester for film base>
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, the temperature is raised by heating, methanol is distilled off, transesterification is performed, and 4 hours are required from the start of the reaction. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, 0.04 part of ethyl acid phosphate, 0.03 part of antimony trioxide and 0.02 part of silica particles having an average particle size of 2.3 μm were added, and the temperature reached 280 ° C. and the pressure reached 15 mmHg in 100 minutes. After that, the pressure was gradually reduced after that to finally reach 0.3 mmHg. After 4 hours, the system was returned to atmospheric pressure to obtain polyethylene terephthalate having an intrinsic viscosity of 0.62.

Example 1:
<Manufacture of water-dispersed polyester resin>
231.8 parts of dimethyl 2,6-naphthalenedicarboxylate, 14.8 parts of 5-sodiumsulfonylisophthaldimethyl, 284.4 parts of ethylene oxide 2-adduct of bisphenol A represented by the following structural formula,

40.4 parts of ethylene oxide 4-adduct of bisphenol A represented by the following structural formula

Was added to an exchange reactor, 0.11 part of tetrabutoxytitanium was added thereto and heated under a nitrogen stream while controlling the temperature at 230 ° C., and the produced methanol was distilled off to carry out a transesterification reaction. Next, 1.2 parts of an antioxidant (trade name: Irganox 1010 manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the reaction system, and then the temperature was gradually raised to 265 ° C. And a polyester resin was obtained.

  100 parts of the polyester and 50 parts of n-butyl cellosolve are charged in a container and dissolved by stirring at 150 to 170 ° C. for about 8 hours, and the temperature is lowered to 70 ° C. to obtain a uniform and viscous solution. Got. While stirring this solution vigorously, 350 parts of water heated to 70 ° C. was gradually added over 1 hour, and stirring was further continued for 1 hour. Thereafter, the liquid temperature was lowered to room temperature to finally obtain an aqueous dispersion (A1) of milky white polyester.

<Adjustment of coating solution>
An aqueous coating agent was blended at the following blending ratio.
Aqueous dispersion of polyester (A1) 97 parts by weight in solid content Aqueous silica sol having an average particle size of 65 nm 3 parts by weight in solid content

<Manufacture of easy-adhesive polyester film>
Polyethylene terephthalate produced for a film base material is dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded from a die, and the surface temperature is adjusted to 40 using an electrostatic application adhesion method. The sheet was cooled and solidified on a cooling roll set to ° C. to obtain an unstretched sheet. Next, the obtained unstretched sheet was first stretched 3.4 times in the longitudinal direction at 95 ° C., and a corona treatment was performed on one side of the film. The coating solution was applied to the corona-treated surface by a bar coating method, then guided to a tenter, and stretched 4.1 times at 110 ° C. in the width direction, and sequentially biaxially stretched. Thereafter, the film was heat-fixed at 225 ° C. for 4 seconds to obtain an easily adhesive polyester film having a thickness of 100 μm and provided with a coating layer having a coating amount (after drying) of 0.1 g / m ² .

  The characteristics of the obtained polyester film are shown in Tables 1 and 2 below. The absolute reflectance of the coating layer surface is 4.8 (minimum wavelength is 680 nm), and the hard coat layer provided on the coating layer surface No interference unevenness was seen and it was good. Also, in terms of adhesion to the hard coat layer, both initial adhesion and wet heat resistance were good.

Example 2:
In Example 1, an easy-adhesive polyester was produced in the same manner as in Example 1 except that the coating solution was as follows.

<Adjustment of coating solution>
An aqueous coating agent was blended at the following blending ratio.
Polyester aqueous dispersion (A1) Solid content weight ratio 77 parts Aqueous melamine-based crosslinking agent Solid content weight ratio 20 parts (trade name Beccamin manufactured by Dainippon Ink & Chemicals, Inc.)
Aqueous silica sol with an average particle size of 65 nm

  The characteristics of the obtained polyester film are shown in Tables 1 and 2, and the absolute reflectance of the coating layer surface is 5.1 (minimum wavelength is 680 nm). The hard coat layer provided on the coating layer surface is The interference unevenness was hardly seen and was good. Also, in terms of adhesion to the hard coat layer, both initial adhesion and wet heat resistance were good.

Comparative Example 1:
<Manufacture of water-dispersed polyester resin>
A reactor was charged with 231.8 parts of dimethyl 2,6-naphthalenedicarboxylate, 14.8 parts of 5-sodiumsulfonylisophthaldimethyl, 68.2 parts of ethylene glycol, and 53.0 parts of diethylene glycol. 11 parts were added and heated under a nitrogen stream while controlling the temperature at 230 ° C., and the produced methanol was distilled off to conduct a transesterification reaction. Next, 1.2 parts of an antioxidant (trade name: Irganox 1010, manufactured by Ciba Specialty Chemicals) was added to the reaction system, and then the temperature was gradually raised to 275 ° C., and the inside of the system was made 1 mmHg to carry out a polycondensation reaction. And a polyester resin was obtained.

  100 parts of the polyester and 50 parts of n-butyl cellosolve are charged in a container and dissolved by stirring at 150 to 170 ° C. for about 8 hours, and the temperature is lowered to 70 ° C. to obtain a uniform and viscous solution. Got. While stirring this solution vigorously, 350 parts of water heated to 70 ° C. was gradually added over 1 hour, and stirring was further continued for 1 hour. Thereafter, the liquid temperature was lowered to room temperature to finally obtain an aqueous dispersion (A2) of milky white polyester.

<Adjustment of coating solution>
An aqueous coating agent was blended at the following blending ratio.

Aqueous dispersion of polyester (A2) 97 parts by weight in solid content Aqueous silica sol having an average particle diameter of 65 nm 3 parts by weight in solid content

<Manufacture of easy-adhesive polyester film>
Polyethylene terephthalate produced for a film base material is dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded from a die, and the surface temperature is adjusted to 40 using an electrostatic application adhesion method. The sheet was cooled and solidified on a cooling roll set to ° C. to obtain an unstretched sheet. Next, the obtained unstretched sheet was first stretched 3.4 times in the longitudinal direction at 95 ° C., and a corona treatment was performed on one side of the film. The coating solution was applied to the corona-treated surface by a bar coating method, then guided to a tenter, and stretched 4.1 times at 110 ° C. in the width direction, and sequentially biaxially stretched. Thereafter, the film was heat-fixed at 225 ° C. for 4 seconds to obtain an easily adhesive polyester film having a thickness of 100 μm and provided with a coating layer having a coating amount (after drying) of 0.1 g / m ² .

  The characteristics of the obtained polyester film are shown in Tables 1 and 2. The absolute reflectance of the coating layer surface is 4.5 (minimum wavelength is 680 nm), and the hard coat layer provided on the coating layer surface is light. Interference unevenness was slightly seen by the way of reflection. In terms of adhesion to the hard coat layer, both initial adhesion and wet heat resistance were poor.

Comparative Example 2:
<Manufacture of water-dispersed polyester resin>
122 parts of dimethyl 2,6-naphthalenedicarboxylate, 87.3 parts of dimethyl isophthalate, 14.8 parts of 5-sodiumsulfonylisophthaldimethyl
284.4 parts of ethylene oxide 2-adduct of bisphenol A represented by the following structural formula,

40.4 parts of ethylene oxide 4-adduct of bisphenol A represented by the following structural formula

The reactor was charged, 0.11 part of tetrabutoxytitanium was added to the reactor, the temperature was controlled at 230 ° C. under a nitrogen stream, and the resulting methanol was distilled off to conduct a transesterification reaction. Next, 1.2 parts of an antioxidant (trade name: Irganox 1010 manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the reaction system, and then the temperature was gradually raised to 265 ° C. And a polyester resin was obtained.

  100 parts of the polyester and 50 parts of n-butyl cellosolve are charged in a container and dissolved by stirring at 150 to 170 ° C. for about 8 hours, and the temperature is lowered to 70 ° C. to obtain a uniform and viscous solution. Got. While stirring this solution vigorously, 350 parts of water heated to 70 ° C. was gradually added over 1 hour, and stirring was further continued for 1 hour. Thereafter, the liquid temperature was lowered to room temperature to finally obtain an aqueous dispersion (A3) of milky white polyester.

<Adjustment of coating solution>
An aqueous coating agent was blended at the following blending ratio.
Aqueous dispersion of polyester (A3) 97 parts by weight in solid content Aqueous silica sol with an average particle size of 65 nm 3 parts by weight in solid content

<Manufacture of easy-adhesive polyester film>
Polyethylene terephthalate produced for a film base material is dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded from a die, and the surface temperature is adjusted to 40 using an electrostatic application adhesion method. The sheet was cooled and solidified on a cooling roll set to ° C. to obtain an unstretched sheet. Next, the obtained unstretched sheet was first longitudinally stretched by 3.4 times at 95 ° C., and the coating solution was applied to one side of the film by a bar coating method, then guided to a tenter and 4.1 times in the lateral direction. Were sequentially biaxially stretched. Thereafter, the film was heat-fixed at 225 ° C. for 4 seconds to obtain an easily adhesive polyester film having a thickness of 100 μm and provided with a coating layer having a coating amount (after drying) of 0.1 g / m ² .

  The properties of the obtained polyester film are shown in Tables 1 and 2. The absolute reflectance of the coating layer surface is 4.6 (minimum wavelength is 680 nm), and the hard coat layer provided on the coating layer surface has The interference unevenness was hardly seen and was good. However, in terms of adhesiveness with the hard coat layer, the initial adhesiveness is insufficient, and the wet heat resistant adhesiveness is further deteriorated and becomes defective.

Comparative Example 3:
<Manufacture of water-dispersed polyester resin>
207.4 parts dimethyl 2,6-naphthalenedicarboxylate, 19.4 parts dimethyl isophthalate, 14.8 parts 5-sodiumsulfonylisophthaldimethyl,
284.4 parts of ethylene oxide 2-adduct of bisphenol A represented by the following structural formula,

40.4 parts of ethylene oxide 4-adduct of bisphenol A represented by the following structural formula

The reactor was charged, 0.11 part of tetrabutoxytitanium was added to the reactor, the temperature was controlled at 230 ° C. under a nitrogen stream, and the resulting methanol was distilled off to conduct a transesterification reaction. Next, 1.2 parts of an antioxidant (trade name: Irganox 1010 manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the reaction system, and then the temperature was gradually raised to 265 ° C. And a polyester resin was obtained.

  100 parts of the polyester and 50 parts of n-butyl cellosolve are charged in a container and dissolved by stirring at 150 to 170 ° C. for about 8 hours, and the temperature is lowered to 70 ° C. to obtain a uniform and viscous solution. Got. While stirring this solution vigorously, 350 parts of water heated to 70 ° C. was gradually added over 1 hour, and stirring was further continued for 1 hour. Thereafter, the liquid temperature was lowered to room temperature to finally obtain an aqueous dispersion (A4) of milky white polyester.

<Adjustment of coating solution>
An aqueous coating agent was blended at the following blending ratio.
Aqueous dispersion of polyester (A4) 97 parts by weight in solid content Aqueous silica sol having an average particle diameter of 65 nm 3 parts by weight in solid content

<Manufacture of easy-adhesive polyester film>
Polyethylene terephthalate produced for a film base material is dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded from a die, and the surface temperature is adjusted to 40 using an electrostatic application adhesion method. The sheet was cooled and solidified on a cooling roll set to ° C. to obtain an unstretched sheet. Next, the obtained unstretched sheet was first stretched 3.4 times in the longitudinal direction at 95 ° C., and a corona treatment was performed on one side of the film. The coating solution was applied to the corona-treated surface by a bar coating method, then guided to a tenter, and stretched 4.1 times at 110 ° C. in the width direction, and sequentially biaxially stretched. Thereafter, the film was heat-fixed at 225 ° C. for 4 seconds to obtain an easily adhesive polyester film having a thickness of 100 μm and provided with a coating layer having a coating amount (after drying) of 0.1 g / m ² .

  The properties of the obtained polyester film are shown in Tables 1 and 2. The absolute reflectance of the coating layer surface is 4.8 (minimum wavelength is 680 nm), and the hard coat layer provided on the coating layer surface has The interference unevenness was hardly seen and was good. However, in terms of adhesiveness with the hard coat layer, initial adhesiveness was somewhat inferior, but wet heat and heat resistant adhesiveness deteriorated and became insufficient.

Comparative Example 4:
<Manufacture of water-dispersed polyester resin>
231.8 parts of dimethyl 2,6-naphthalenedicarboxylate, 14.8 parts of 5-sodiumsulfonylisophthaldimethyl, 252.8 parts of bisphenol A ethylene oxide 2-adduct represented by the following structural formula, 12.4 parts of ethylene glycol

40.4 parts of ethylene oxide 4-adduct of bisphenol A represented by the following structural formula

Was added to the reactor, 0.11 part of tetrabutoxytitanium was added to the reactor, the temperature was controlled at 230 ° C. under a nitrogen stream, and the resulting methanol was distilled off to conduct a transesterification reaction. Next, 1.2 parts of an antioxidant (trade name: Irganox 1010 manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the reaction system, and then the temperature was gradually raised to 265 ° C. And a polyester resin was obtained.

  100 parts of the polyester and 50 parts of n-butyl cellosolve are charged in a container and dissolved by stirring at 150 to 170 ° C. for about 8 hours, and the temperature is lowered to 70 ° C. to obtain a uniform and viscous solution. Got. While stirring this solution vigorously, 350 parts of water heated to 70 ° C. was gradually added over 1 hour, and stirring was further continued for 1 hour. Thereafter, the liquid temperature was lowered to room temperature to finally obtain an aqueous dispersion (A5) of milky white polyester.

<Adjustment of coating solution>
An aqueous coating agent was blended at the following blending ratio.

Aqueous dispersion of polyester (A5) 97 parts by weight in solid content Aqueous silica sol having an average particle size of 65 nm 3 parts by weight in solid content

<Manufacture of easy-adhesive polyester film>
Polyethylene terephthalate produced for a film base material is dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded from a die, and the surface temperature is adjusted to 40 using an electrostatic application adhesion method. The sheet was cooled and solidified on a cooling roll set to ° C. to obtain an unstretched sheet. Next, the obtained unstretched sheet was first stretched 3.4 times in the longitudinal direction at 95 ° C., and a corona treatment was performed on one side of the film. The coating solution was applied to the corona-treated surface by a bar coating method, then guided to a tenter, and stretched 4.1 times at 110 ° C. in the width direction, and sequentially biaxially stretched. Thereafter, the film was heat-fixed at 225 ° C. for 4 seconds to obtain an easily adhesive polyester film having a thickness of 100 μm and provided with a coating layer having a coating amount (after drying) of 0.1 g / m ² .

  The properties of the obtained polyester film are shown in Tables 1 and 2. The absolute reflectance of the coating layer surface is 4.6 (minimum wavelength is 680 nm), and the hard coat layer provided on the coating layer surface has The interference unevenness was hardly seen and was good. In terms of adhesiveness with the hard coat layer, the initial adhesiveness was insufficient, but the wet heat-resistant adhesiveness did not change.

In Table 1, the abbreviations of “polyester composition in the coating film” are as follows.
NDCA: 2,6-naphthalenedicarboxylic acid IPA: isophthalic acid 5-SIP: sodium 5-sulfonylisophthalate BPA-2: bisphenol A ethylene oxide 2-adduct BPA-4: bisphenol A ethylene oxide 4-adduct EG: ethylene glycol DEG : Diethylene glycol

  The film of the present invention can be suitably used for optical applications such as display members such as LCD, PDP, and organic EL, and films for manufacturing the same.

Claims (1)

At least one surface of a polyester film stretched at least in a uniaxial direction is substantially composed of 2,6-naphthalenedicarboxylic acid as a dicarboxylic acid component and an aromatic dicarboxylic acid having an anionic group, and is substantially bisphenol as a glycol component. An easily adhesive polyester film comprising a coating layer containing a polyester resin composed of an ethylene oxide adduct of A.