JP2020063457A - Method of producing easily adhesive polyester film - Google Patents

Abstract

To provide an easily adhesive polyester film which is excellent for all aspects of low interference for suppression of iridescent irregularity, and adhesion to a hard coat layer, anti-blocking properties and transparency required at a high level in various optical applications, further has high sliding properties, is excellent in handling properties in production or in steps subsequent to a step of producing a polarizing plate of a liquid display device, thereby being suitable for use in optical applications.SOLUTION: There is provided a method of producing an easily adhesive polyester film that has, on at least one surface of a polyester film, a coating layer containing a polyurethane resin having a polycarbonate backbone and a polyester resin having a naphthalene backbone, in which when the contained amount a of the polyurethane resin component, the contained amount b of the polyester resin component having a naphthalene backbone, and the total amount c of the other components are plotted in a triangular diagram, where the total solid content of the coating layer is 100 mass%, a, b and c are within a region surrounded by specific four straight lines. In the method, an in-line coating method is employed as a coating method.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing an easily-adhesive polyester film that can secure low interference that can solve the problem of rainbow unevenness, and that is excellent in adhesion to various functional layers, blocking resistance, and transparency. More specifically, it relates to a method for producing an easily-adhesive polyester film which can be suitably used even in high-definition optical applications.

  A hard coat film in which a transparent hard coat layer is laminated is used on the front surface of a display such as a touch panel, a computer, a television, a liquid crystal display device, and a decorative material. A transparent polyester film is generally used as the transparent plastic film of the base material, and in order to improve the adhesion between the polyester film of the base material and the hard coat layer, easy adhesion is provided as an intermediate layer between them. In many cases, a coating layer having the same is provided.

  The hard coat film is required to have resistance to temperature, humidity and light, transparency, chemical resistance, scratch resistance, antifouling property and the like. In addition, since it is often used on the surface of a display or a decorative material, visibility and designability are required. Therefore, in order to suppress glare and iris color due to reflected light when viewed from an arbitrary angle, the antireflection of a multilayer structure in which a high refractive index layer and a low refractive index layer are laminated on top of the hard coat layer. It is common practice to provide layers.

  However, in applications such as displays and decorations, in recent years, further larger screens (larger areas) and higher resolutions have been demanded, and accordingly, there is a demand for suppression of iris-like colors (interference spots) particularly under fluorescent lamps. The level is getting higher. In addition, the three-wavelength type of fluorescent lamps has become the mainstream due to the reproducibility of daylight color, and interference spots are more likely to occur. Furthermore, there is an increasing demand for cost reduction by simplifying the antireflection layer. Therefore, there is a demand for a hard coat film that does not have an antireflection layer to suppress interference spots as much as possible.

  Further, the development of mobile technology has expanded the use of mobile devices such as mobile phones, car navigation systems and electronic books in the outdoor area. In addition, most of the above-mentioned portable devices are liquid crystal panel displays from the viewpoint of thinning. In such fields, for example, in a mobile phone equipped with a touch panel, as a hard coat film for protecting the surface of the display, interference fringes due to reflected light from both interfaces in contact with the coating surface or an icon sheet is used as a design on the back surface of the hard coat film. In the application to improve the property, the defect of visibility due to the interference fringes is becoming more apparent.

  The iris-like color (interference spots) of the hard coat film is the same as the refractive index of the base polyester film (for example, 1.62 to 1.65) and the refractive index of the hard coat layer made of acrylic resin (for example, 1.49). It is said that this occurs because the difference between the two is large. In order to reduce the difference in the refractive index between the laminated layers and prevent the occurrence of interference spots, a coating layer having a relatively high refractive index is provided on the polyester film of the substrate, and the difference in the refractive index between the polyester film and the coating layer, the coating layer And a method of reducing the difference in the refractive index of the hard coat layer have been proposed.

  Conventionally, in the field of optical easy-adhesive films, as a method of increasing the refractive index of the easy-adhesion layer, a method of including specific high refractive index fine particles in the coating layer, a method of increasing the refractive index of the resin of the coating layer, etc. It has been known. In particular, a polyester resin using a naphthalenedicarboxylic acid component as a copolymerization component of naphthalenedicarboxylic acid has excellent adhesion to a base polyester film and has been proposed as a suitable example (see, for example, Patent Document 1). However, in general, a polyester resin having a high refractive index has a high glass transition temperature and may have poor adhesion due to lack of flexibility of the resin, or blocking resistance may be deteriorated when the amount of the polyester resin is increased. there were. On the other hand, a method of using a polyurethane resin having a polycarbonate component as a resin having excellent flexibility and high adhesion has been proposed (see, for example, Patent Document 2), and Patent Document 1 also blends a polyurethane resin having a polycarbonate component. However, when the amount of the polyurethane component is increased, there are problems such as low interference and poor transparency. Thus, conventionally, while responding to the recent high level of low interference, adhesion with the hard coat layer, blocking resistance, an easily adhesive polyester film having a high balance of transparency has been obtained. There wasn't.

JP, 2011-246663, A JP, 2011-168053, A

The present invention has been made against the background of the problems of the related art. That is, the object of the present invention is excellent in any of low interference that can suppress rainbow unevenness, adhesion with a hard coat layer and the like required in a high dimension in various optical applications, blocking resistance, transparency, and even higher. It is an object of the present invention to provide a method for producing an easily-adhesive polyester film which has a slip property and can be suitably used in optical applications which are excellent in handleability at the time of production and in a later step such as a polarizing plate production step of a liquid crystal display device.

That is, the present invention has the following configurations.
1. Polyurethane resin having a polycarbonate skeleton, a coating layer containing a polyester resin having a naphthalene skeleton is provided on at least one surface of the polyester film, and the content of the polyurethane resin component when the total solid content of the coating layer is 100% by mass (mass) %) Is a, the content (% by mass) of the polyester resin component having a naphthalene skeleton is b, and the total amount (% by mass) of the components other than these is c in a triangular chart, where a, b, and c are straight lines. A method for producing an easily adhesive polyester film in a region surrounded by four straight lines P1, a straight line Q1, a straight line R1, and a straight line S1, wherein the easy adhesive polyester film adopts an in-line coating method as a coating method. Manufacturing method .
Here, the straight line P1, the straight line Q1, the straight line R1, and the straight line S1 are as follows.

Straight line P1: a straight line Q1 passing through a point where a is 10 mass%, b is 55 mass% and c is 35 mass% and a point is 10 mass%, b is 10 mass% and c is 80 mass% : A straight line R1: a passing through a point where a is 10% by mass, b is 10% by mass and c is 80% by mass, and a point is 70% by mass, b is 10% by mass and c is 20% by mass. Is 70% by mass, b is 10% by mass, c is 20% by mass, and a straight line S1: a is 45 which passes through a point of 50% by mass of a, 40% by mass of b and 10% by mass of c. A straight line that passes through the points where mass%, b is 45 mass%, c is 10 mass%, and a is 10 mass%, b is 55 mass%, and c is 35 mass%.

2. The method for producing an easily adhesive polyester film as described in the above item 1, wherein the coating layer contains a crosslinking agent.
3. 3. The method for producing an easily adhesive polyester film according to the above 1 or 2, wherein the coating layer contains metal oxide particles (particles A) having a refractive index of 1.7 or more.
4. The method for producing an easily-adhesive polyester film according to any one of the above first to third, wherein the coating layer contains lubricant particles (particles B).
5. Selected from the group consisting of a hard coat layer, an antiglare layer, an antiglare antireflection layer, an antireflection layer and a low reflection layer on the coating layer of the easily adhesive polyester film according to any one of the first to fourth aspects. And a method for producing a laminated polyester film having one or more functional layers.

According to the present invention, there is provided a method for producing an easily-adhesive polyester film which can suppress rainbow unevenness, is excellent in transparency, blocking resistance, adhesiveness with various functional layers, is excellent in slipperiness, and can be suitably used in optical applications. Became possible.

3 is a triangular chart showing a preferable range in the easily adhesive polyester film of the present invention.

(Polyester film)
The polyester film used as the substrate in the present invention is a film made of a polyester resin, and is preferably a polyester film containing at least one of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate and polyethylene naphthalate as a constituent component. . Further, it may be a film made of a copolyester obtained by copolymerizing a third component monomer with the above polyester. Among these polyester films, the polyethylene terephthalate film is most preferable from the viewpoint of balance between physical properties and cost.

  Further, the polyester film may be a single layer or a multilayer. In addition, each of these layers may contain various additives in the polyester resin, if necessary, as long as the effects of the present invention are achieved. Examples of the additive include an antioxidant, a light resistance agent, an antigelling agent, an organic wetting agent, an antistatic agent, an ultraviolet absorber and a surfactant.

(Coating layer)
The easily-adhesive polyester film in the present invention is one in which an easily-adhesive coating layer is laminated on the above-mentioned polyester base film.
The coating layer in the present invention has a content (mass%) of the polyurethane resin component having a polycarbonate skeleton and a content of the polyester resin component having a naphthalene skeleton (when the total amount (solid content) of the coating layer is 100% by mass). (% By mass) is b, and the total amount (% by mass) of components other than these is c as a triangular chart, a, b, and c are surrounded by four straight lines P1, straight line Q1, straight line R1, and straight line S1. It is preferable that it is within the range of the open area.

Here, the straight line P1, the straight line Q1, the straight line R1, and the straight line S1 are as follows.
Straight line P1: a straight line Q1 passing through a point where a is 10 mass%, b is 55 mass% and c is 35 mass% and a point is 10 mass%, b is 10 mass% and c is 80 mass% : A straight line R1: a passing through a point where a is 10% by mass, b is 10% by mass and c is 80% by mass, and a point is 70% by mass, b is 10% by mass and c is 20% by mass. Is 70% by mass, b is 10% by mass, c is 20% by mass, and a straight line S1: a is 45 which passes through a point of 50% by mass of a, 40% by mass of b and 10% by mass of c. A straight line that passes through the points where mass%, b is 45 mass%, c is 10 mass%, and a is 10 mass%, b is 55 mass%, and c is 35 mass%.

  Within the above range, low interference (interference fringe improvement), adhesion, blocking resistance, and transparency can be maintained at a high level with good balance.

  The above preferable range will be briefly described with reference to the triangular chart shown in FIG. On the three sides of the triangular chart, the content of the polyurethane resin component having a polycarbonate skeleton a (mass%), the content of the polyester resin component having a naphthalene skeleton b (mass%) and other components c (mass%) Each coordinate axis is shown. Here, if the coordinates inside the triangle chart are written in the order of (a, b, c), five coordinates (10, 55, 35), (10, 10, 80), (70 , 10, 20), (50, 40, 10) and (45, 45, 10) are shown. Then, a straight line P1 passing through (10, 55, 35) and (10, 10, 80), a straight line Q1 passing through (10, 10.80) and (70, 10, 20), (70, 10, 20) ) And (50, 40, 10), and a straight line R1 passing through (45, 45, 10) and (10.55, 35). The inner range surrounded by indicates the range where low interference (interference fringe improvement), adhesion, blocking resistance, and transparency can be provided in a well-balanced manner.

Further, the more preferable range of each straight line will be described below.
Instead of the straight line P1, a straight line P2 (a is 15 mass%, b is 55 mass%, c is 30 mass%, a is 15 mass%, b is 10 mass%, and c is 75 mass%. It is preferable to adopt a straight line that passes through and.

Instead of the straight line Q1, a straight line Q2 (a is 10 mass%, b is 20 mass%, c is 70 mass%, a is 70 mass%, b is 10 mass%, and c is 20 mass%. And a straight line Q3 (a is 20 mass%, b is 20 mass%, c is 60 mass%, a is 70 mass%, b is 10 mass%, and c is 20 mass%. It is preferable to adopt a straight line that passes through the point and.

  Instead of the straight line R1, a straight line R2 (a is 65 mass%, b is 10 mass%, c is 25 mass% and a is 45 mass%, b is 40 mass%, and c is 15 mass% And a straight line R3 (a is 60 mass%, b is 10 mass%, c is 30 mass%, a is 40 mass%, b is 40 mass%, and c is 20 mass%. It is preferable to adopt a straight line that passes through the point and.

  Instead of the straight line S1, a straight line S2 (a is 50 mass%, b is 40 mass%, c is 10 mass%, and a is 10 mass%, b is 50 mass%, and c is 40 mass%. And a straight line S3 (a is 52 mass%, b is 38 mass%, c is 10 mass%, a is 10 mass%, b is 48 mass%, and c is 42 mass%. A straight line passing through), especially S4 (a mass of 55 mass%, b mass of 35 mass%, c mass of 10 mass%, a mass of 10 mass%, b mass of 45 mass%, and c mass of 45 mass). It is preferable to adopt a straight line that passes through the% point.

The lower limit of the content a of the polyurethane resin component having a polycarbonate skeleton is preferably 10% by mass, more preferably 13% by mass, and further preferably 15% by mass. When the content a of the polyurethane resin component having a polycarbonate skeleton is 10% by mass or more, the transparency is not impaired and the adhesiveness is satisfied, which is preferable.
The upper limit of the content a of the polyurethane resin component having a polycarbonate skeleton is preferably 70% by mass, more preferably 60% by mass, further preferably 50% by mass, and particularly preferably 40% by mass. When the content a of the polyurethane resin component having a polycarbonate skeleton is 70% by mass or less, the refractive index can be kept high and low interference can be obtained, which is preferable.

The lower limit of the content b of the polyester resin component having a naphthalene skeleton is preferably 10% by mass, more preferably 15% by mass, and further preferably 20% by mass. When the content b of the polyester resin component having a naphthalene skeleton is 10% by mass or more, the adhesiveness is satisfied, which is preferable.
The upper limit of the content b of the polyester resin component having a naphthalene skeleton is preferably 55% by mass, more preferably 50% by mass, further preferably 48% by mass, and particularly preferably 45% by mass. When the content b of the polyester resin component having a naphthalene skeleton is 55% by mass or less, blocking resistance is exhibited, which is preferable.

The lower limit of the content c of the other components is preferably 10% by mass, more preferably 20% by mass, further preferably 25% by mass, and particularly preferably 30% by mass. When the content c of the other components is 10% by mass or more, it is preferable that the components that increase the refractive index of the coating layer are contained, because the low coherence is improved. Further, as a result, the content a of the polyurethane resin having a polycarbonate skeleton does not become too large, and blocking can be prevented, which is preferable.
The upper limit of the content c of the other components is preferably 80% by mass, more preferably 70% by mass, further preferably 60% by mass, and particularly preferably 55% by mass. When the content c of the other components is 80% by mass or less, as a result, the content a of the polyurethane resin component having a polycarbonate skeleton and the content b of the polyester resin component having a naphthalene skeleton are easily balanced, and the adhesiveness is improved. Is maintained, and the blocking resistance and the refractive index (low interference) are easily balanced, which is preferable.

(Polyurethane resin having a polycarbonate skeleton)
The diol component, which is a constituent of the polyurethane resin having a polycarbonate skeleton, preferably contains an aliphatic polycarbonate polyol having excellent heat resistance and hydrolysis resistance. In the optical use of the present invention, it is preferable to use an aliphatic polycarbonate polyol from the viewpoint of preventing yellowing.

  Examples of the aliphatic polycarbonate polyol include an aliphatic polycarbonate diol and an aliphatic polycarbonate triol, and the aliphatic polycarbonate diol can be preferably used. Examples of the aliphatic polycarbonate diol which is a constituent component of the urethane resin of the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 3-methyl. -1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4- Aliphatic polycarbonate diols obtained by reacting one or more diols such as cyclohexanedimethanol with carbonates such as dimethyl carbonate, diphenyl carbonate, ethylene carbonate and phosgene It is below.

The polyurethane resin having a polycarbonate skeleton is a ratio (A1460 /) of the absorbance (A1460) near the aliphatic polycarbonate component-derived 1460 cm ^{−1 and} the absorbance near the urethane component-derived 1530 cm ⁻¹ (A1530) measured by infrared spectroscopy. A1530) is preferably 0.40 to 2.30.
When the ratio (A1460 / A1530) is 0.40 or more, the hardened urethane component does not increase too much, stress relaxation of the coating layer does not decrease, and the wet heat resistance does not decrease, which is preferable. Further, when the ratio (A1460 / A1530) is 2.30 or less, the aliphatic component of the flexible aliphatic polycarbonate does not increase too much, the solvent resistance of the coating layer is maintained, and the wet heat resistance may decrease. There is no and is preferable.

  In order to set the ratio (A1460 / A1530) in the range of 0.40 to 2.30, the number average molecular weight of the aliphatic polycarbonate diol is preferably 1500 to 4000, more preferably 2000 to 3000. When the number average molecular weight of the aliphatic polycarbonate diol is small, the ratio of the aliphatic polycarbonate component constituting the urethane resin becomes relatively small.

Examples of the polyisocyanate which is a constituent of the urethane resin in the present invention include aromatic aliphatic diisocyanates such as xylylene diisocyanate, isophorone diisocyanate and 4,4-dicyclohexylmethane diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane. Alicyclic diisocyanates such as, hexamethylene diisocyanate, and aliphatic diisocyanates such as 2,2,4-trimethylhexamethylene diisocyanate, or a polyadduct of these compounds previously added with trimethylolpropane or the like in a single or plural number. Isocyanates may be mentioned. The above-mentioned polyisocyanates are preferable for optical use which does not have the problem of yellowing and which requires high transparency. Further, such a polyisocyanate is preferable because the coating film does not become too hard and the stress due to shrinkage and swelling of the photocurable resin or the like can be relaxed and the adhesiveness is maintained.

  In order to impart water solubility to the urethane resin, a sulfonic acid (salt) group or a carboxylic acid (salt) group can be introduced (copolymerized) into the urethane molecular skeleton. Since the sulfonic acid (salt) group is strongly acidic and it may be difficult to maintain the moisture resistance due to its hygroscopic property, it is preferable to introduce a weakly acidic carboxylic acid (salt) group. Also, a nonionic group such as a polyoxyalkylene group can be introduced.

  To introduce a carboxylic acid (salt) group into the urethane resin, for example, a polyol component having a carboxylic acid group such as dimethylolpropionic acid and dimethylolbutanoic acid is introduced as a copolymerization component to form a salt. Neutralize with agent. Specific examples of the salt forming agent include ammonia, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, tri-n-butylamine and other trialkylamines, N-methylmorpholine, N-ethylmorpholine and other N Examples include N-dialkylalkanolamines such as -alkylmorpholines, N-dimethylethanolamine, and N-diethylethanolamine. These can be used alone or in combination of two or more.

  When a polyol compound having a carboxylic acid (salt) group is used as a copolymerization component for imparting water solubility, the composition molar ratio of the polyol compound having a carboxylic acid (salt) group in the urethane resin is When the total polyol component is 100 mol%, it is preferably 3 to 60 mol%, and more preferably 5 to 40 mol%. When the composition molar ratio is 3 mol% or more, the water dispersibility is good, which is preferable. Further, when the composition molar ratio is 60 mol% or less, water resistance is maintained and wet heat resistance is maintained, which is preferable.

The glass transition temperature of the urethane resin in the present invention is preferably lower than 0 ° C, more preferably lower than -5 ° C. When the glass transition temperature is lower than 0 ° C, suitable flexibility is easily exhibited in terms of stress relaxation of the coating layer, which is preferable.

(Polyester resin having a naphthalene skeleton)
By containing a naphthalene dicarboxylic acid-derived component as the acid component of the polyester resin contained in the coating layer, the refractive index is increased, and the iris color under a fluorescent lamp can be easily controlled. In addition, it becomes possible to improve the moist heat resistance.

  As such naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid is preferable. The proportion of the above-mentioned naphthalene dicarboxylic acid in all dicarboxylic acid components constituting the polyester resin is preferably 20 mol% or more, more preferably 30 mol% or more, further preferably 50 mol% or more, still more preferably 60 mol% or more.

  Further, as long as the effects of the present invention are exhibited, as acid components in the polyester resin, terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 1,4-cyclohexanedicarboxylic acid, trimellitic acid, pyromellitic acid are further added. , Dimer acid, 5-sodium sulfoisophthalic acid, 4-sodium sulfonaphthalene-2,7-dicarboxylic acid, adipic acid, azelaic acid, sebacic acid, etc. may be used. When these are copolymerized, the aromatic dicarboxylic acid component including naphthalene dicarboxylic acid is preferably 70 mol% or more, and more preferably 80 mol% or more, from the viewpoint of resistance to moist heat and high refraction. Particularly when importance is attached to moist heat resistance and high refractivity, the aromatic dicarboxylic acid component is preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 100%.

  As long as the effects of the present invention are achieved, ethylene glycol, 1,3-propane glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol are further used as the diol component in the polyester resin. , Diethylene glycol, 1,4-cyclohexanedimethanol, xylene glycol, ethylene oxide adduct of bisphenol A and the like may be used.

Further, when the content of the polyurethane resin having a polycarbonate skeleton in the coating layer is reduced, the flexibility of the coating film becomes poor, and the coating layer may be scraped or particles may fall off in the post-processing treatment or the like. In such a case, it is one of the preferable modes to include the dicarboxylic acid component represented by the following formula (1) and / or the diel component represented by the following formula (2) in the polyester resin.
(1) HOOC- (CH2) n-COOH (In the formula, n is an integer of 4≤n≤10)
(2) HO- (CH2) n-OH (where n is an integer of 4≤n≤10)

By containing the acid component and / or the diol component having a carbon component of a specific length in this way, flexibility is imparted to the polyester resin, and even relatively large particles are easily retained, and the coating layer It is possible to suppress the abrasion of the particles and the dropping of the particles.
Examples of the dicarboxylic acid component of the formula (1) include adipic acid, sebacic acid and azelaic acid. Moreover, butanediol, hexanediol, etc. are mentioned as a diol component of Formula (2).

  The polyester resin can be used with respect to water or a water-soluble organic solvent (eg, an aqueous solution containing less than 50% by mass of alcohol, alkyl cellosolve, a ketone type, an ether type) or an organic solvent (eg, toluene, ethyl acetate, etc.). What was dissolved or dispersed can be used.

  When the polyester resin is used as an aqueous coating liquid, a water-soluble or water-dispersible polyester resin is used. For such water-solubilization or water-dispersion, a compound containing a sulfonate group or a carboxyl group is used. It is preferable to copolymerize a compound containing an acid base.

  The number average molecular weight of the polyester resin is preferably 5,000 to 40,000 from the viewpoint of coating film strength, water dispersibility and the like. It is more preferably 10,000 to 30,000, and particularly preferably 12,000 to 25,000.

  The polyester resin containing the naphthalene dicarboxylic acid component may be a single resin or a blend of two or more kinds. In the case of a blend of two or more kinds, it is preferable that the total composition of the polyester resin components is the above composition.

  Other components contained in the coating layer include a binder resin other than a polyurethane resin having a polycarbonate skeleton and a polyester resin containing a naphthalene dicarboxylic acid component, a crosslinking agent, lubricant particles, and metal oxide particles for increasing the refractive index of the coating layer. , A surfactant, etc., but in the present invention, it is preferable to contain a crosslinking agent, lubricant particles, and metal oxide particles for increasing the refractive index of the coating layer. The coating liquid contains a solvent and may also contain a surfactant, but the mass of the solvent remaining after drying and curing and the mass of the solid content of the surfactant are extremely small, When calculating the composition of each component in the calculation, the mass of the residual solvent and the mass of the solid content of the surfactant do not necessarily have to be included in the mass of the solid content of the entire coating layer, and the description of the composition of the example is given in the above calculation. Is based on.

  In order to form a crosslinked structure in the coating layer, the coating layer may contain a crosslinking agent. By including a cross-linking agent, it becomes possible to further improve the adhesiveness under high temperature and high humidity. Specific crosslinking agents include urea-based, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, carbodiimide-based and the like. Among these, melamine-based, isocyanate-based, oxazoline-based, and carbodiimide-based cross-linking agents are preferable from the viewpoint of the stability of the coating liquid over time and the effect of improving the adhesion under high temperature and high humidity treatment. Further, in order to accelerate the crosslinking reaction, a catalyst or the like can be appropriately used if necessary.

  When the coating layer contains a cross-linking agent, the content of the cross-linking agent is preferably 5% by mass or more and 50% by mass or less based on the total solid components of the coating layer. More preferably, it is 10% by mass or more and 40% by mass or less. When the content is 10% by mass or more, the strength of the resin in the coating layer is maintained, the adhesion under high temperature and high humidity is good, and when the content is 40% by mass or less, the flexibility of the resin in the coating layer is maintained, Adhesion at room temperature and high temperature and high humidity is maintained, which is preferable.

In addition, it is preferable to include high-refractive-index metal oxide particles (particles A) having a refractive index of 1.7 or more in the coating layer. Such metal oxides include TiO ₂ (refractive index 2.7), ZnO (refractive index 2.0), Sb ₂ O ₃ (refractive index 1.9), SnO ₂ (refractive index 2.1), ZrO ₂ (refractive index 2.4), Nb ₂ O ₅ (refractive index 2.3), CeO ₂ (refractive index 2.2), Ta ₂ O ₅ (refractive index 2.1), Y ₂ O ₃ (refractive index) Index 1.8), La ₂ O ₃ (refractive index 1.9), In ₂ O ₃ (refractive index 2.0), Cr ₂ O ₃ (refractive index 2.5), etc., and these metal atoms are included. Examples thereof include composite oxide particles.

  The lower limit of the refractive index of the particles A is preferably 1.7, more preferably 1.75. The upper limit of the refractive index of the particles A is preferably 3.0, more preferably 2.7, and further preferably 2.5. Within the above range, low interference, transparency, adhesion and blocking resistance can be well balanced.

The composite oxide particles used as the particles A are preferably TiO ₂ / ZnO particles (zirconia / titania mixed particles). The zirconia / titania mixed particles are a group of particles containing both zirconia and titania in an aggregated state in which zirconia and titania are individually dispersed in a single liquid and do not form a complex. Of course, the liquid component in the coating layer is almost completely evaporated in the drying process and the curing process. By including such particles A in the coating layer, a good balance between slipperiness and transparency can be obtained, and high transparency and low interference can be secured. The liquid is preferably an aqueous liquid so that the coating layer can be easily formed by a so-called in-line coating method described later.

  The zirconia / titania mixed particles may contain components other than zirconia / titania, may be inorganic particles or organic particles, and are not particularly limited, but silica, Inorganic particles that are inert to metal oxides such as titanium dioxide (titania), zirconium oxide (zirconia), talc, kaolinite, and polyesters such as calcium carbonate, calcium phosphate, and barium sulfate are exemplified.

  The average particle size of the particles A is preferably 5 nm or more, more preferably 10 nm or more, further preferably 15 nm or more, and particularly preferably 20 nm or more. It is preferable that the average particle diameter of the particles A is 5 nm or more because aggregation is less likely to occur.

  The average particle size of the particles A is preferably 200 nm or less, more preferably 150 nm or less, further preferably 100 nm or less, and particularly preferably 60 nm or less. It is preferable that the average particle size of the particles A is 200 nm or less, because the transparency is good.

  In the present invention, it is preferable to include lubricant particles (particles B) in the coating layer.

  The particles B are (1) silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, titanium dioxide, satin white, aluminum silicate. , Inorganic particles such as diatomaceous earth, calcium silicate, aluminum hydroxide, hydrohalloysite, magnesium carbonate, magnesium hydroxide, (2) acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene / acrylic, Styrene / butadiene system, polystyrene / acrylic system, polystyrene / isoprene system, polystyrene / isoprene system, methylmethacrylate / butylmethacrylate system, melamine system, polycarbonate system, urea system, epoxy system, urethane system, phenol system Diallyl phthalate, but include organic particles of polyester or the like, to give an appropriate sliding property to the coating layer, silica is particularly preferably used.

  The average particle size of the particles B is preferably 200 nm or more, more preferably 250 nm or more, further preferably 300 nm or more, and particularly preferably 350 nm or more. It is preferable that the average particle diameter of the particles B is 200 nm or more because aggregation is less likely to occur and slipperiness can be secured.

  The average particle size of the particles B is preferably 2000 nm or less, more preferably 1500 nm or less, further preferably 1000 nm or less, and particularly preferably 700 nm or less. When the average particle diameter of the particles B is 2000 nm or less, transparency is maintained and the particles do not fall off, which is preferable.

  The particles A and B may be surface-treated, and the surface treatment methods include physical surface treatment such as plasma discharge treatment and corona discharge treatment and chemical surface treatment using a coupling agent. Is preferably used. As the coupling agent, an organoalkoxy metal compound (eg, titanium coupling agent, silane coupling agent) is preferably used. When the particles B are silica, the silane coupling treatment is particularly effective. It may be used as a surface treatment agent for the particles B for preliminarily performing a surface treatment before preparing the layer coating solution, or may be added to the layer as an additive when preparing the layer coating solution. Of course, it may be used for the particles A.

  The content of the particles A in the coating layer is preferably 2% by mass or more, more preferably 3% by mass or more, further preferably 4% by mass or more, and particularly preferably 5% by mass or more. When the content of the particles A in the coating layer is 2% by mass or more, the refractive index of the coating layer can be kept high, and low coherence can be effectively obtained, which is preferable.

  The content of particles A in the coating layer is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, and particularly preferably 20% by mass or less. When the content of the particles A in the coating layer is 50% by mass or less, the film forming property is maintained, which is preferable.

  The content of particles B in the coating layer is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more. When the content of the particles B in the coating layer is 0.01% by mass or more, suitable slipperiness is maintained, which is preferable.

  The content of particles B in the coating layer is preferably 2% by mass or less, more preferably 1.5% by mass or less, and further preferably 1% by mass or less. When the content of the particles B in the coating layer is 2% by mass or less, the haze is kept low, which is preferable in terms of transparency.

  The thickness of the coating layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, still more preferably 0.02 μm or more, and particularly preferably 0.05 μm or more. When the thickness of the coating layer is 0.001 μm or more, the adhesiveness is good, which is preferable.

  The thickness of the coating layer is preferably 2 μm or less, more preferably 1 μm or less, further preferably 0.8 μm or less, and particularly preferably 0.5 μm or less. When the thickness of the coating layer is 2 μm or less, blocking is not likely to occur, which is preferable.

The coating layer may contain a surfactant for the purpose of improving the leveling property during coating and defoaming the coating liquid. The surfactant may be any of cationic, anionic and nonionic surfactants, but silicone, acetylene glycol or fluorine surfactants are preferred. It is preferable that these surfactants are contained in the coating layer in a range that does not impair the effect of suppressing the iris color under fluorescent light and the adhesiveness.

  In order to impart other functionality to the coating layer, various additives may be contained within a range that does not impair the effect of suppressing iris color under fluorescent light and the adhesiveness. Examples of the additives include fluorescent dyes, fluorescent brighteners, plasticizers, ultraviolet absorbers, pigment dispersants, foam suppressors, defoamers, and preservatives.

  As the coating method, a so-called in-line coating method in which the polyester base film is coated at the time of film formation, and a so-called offline coating method in which a polyester base film is coated and then separately coated by a coater can be applied. The in-line coating method is more efficient and more preferable.

  As a coating method, any known method can be used as a method for applying the coating liquid to a polyethylene terephthalate (hereinafter abbreviated as PET) film. For example, reverse roll coating method, gravure coating method, kiss coating method, die coater method, roll brushing method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, curtain coating method, etc. To be These methods are applied individually or in combination.

  In the present invention, examples of the method for providing the coating layer on the polyester film include a method in which a coating solution containing a solvent, particles and a resin is applied to the polyester film and dried. Examples of the solvent include organic solvents such as toluene, water, or a mixed system of water and a water-soluble organic solvent, but from the viewpoint of environmental problems, water alone or a mixture of water and a water-soluble organic solvent is preferable. preferable.

The solid content concentration of the coating liquid depends on the type of binder resin and the type of solvent, but is preferably 2% by mass or more, and more preferably 4% by mass. Solid content of coating liquid is 3
It is preferably 5% by mass or less, and more preferably 15% by mass or less.

  The drying temperature after coating also depends on the type of binder resin, the type of solvent, the presence / absence of a crosslinking agent, the solid content concentration, etc., but is preferably 80 ° C. or higher, and preferably 250 ° C. or lower.

  The surface roughness (Ra) of the coating layer is related to the slipperiness and the like of the surface of the coating layer, and is preferably 0.01 nm or more, more preferably 0.1 nm or more, further preferably 0.2 nm or more. And particularly preferably 0.5 nm or more. On the other hand, the upper limit of the surface roughness (Ra) of the coating layer is preferably 200 nm or less, more preferably 100 nm or less, still more preferably 80 nm or less, and particularly preferably 50 nm or less.

(Production of easily adhesive polyester film for optics)
Highly adhesive polyester film for optical in the present invention can be produced according to the production method of the general polyester film. For example, a polyester resin is melted, and a non-oriented polyester extruded and molded into a sheet is stretched in the machine direction at a temperature of a glass transition temperature or higher by using a speed difference of rolls, and then stretched in a transverse direction by a tenter, A method of performing heat treatment can be mentioned.

The polyester film in the present invention may be a uniaxially stretched film or a biaxially stretched film, but when the biaxially stretched film is used as a protective film for the front surface of the liquid crystal panel, it is observed from directly above the film surface. Even though no iridescent color spots are seen, it should be noted that iridescent color spots may be observed when observed from an oblique direction.

  This phenomenon is because the biaxially stretched film consists of an index ellipsoid having different refractive indices in the running direction, the width direction, and the thickness direction, and the in-plane retardation becomes zero depending on the light transmission direction inside the film (refraction This is because there is a direction. Therefore, when the liquid crystal display screen is observed from a specific oblique direction, a point where the in-plane retardation becomes zero may occur, and rainbow-shaped color spots concentrically occur around the point. When the angle from the position directly above the film surface (in the normal direction) to the position where the iridescent color spots are visible is θ, this angle θ increases as the birefringence in the film surface increases, resulting in an iridescent color. The spots are hard to see. Since the angle θ tends to be small in the biaxially stretched film, the uniaxially stretched film is preferable because the rainbow-like color spots are less visible.

  However, a perfect uniaxial (uniaxially symmetric) film is not preferable because the mechanical strength in the direction orthogonal to the orientation direction is significantly reduced. INDUSTRIAL APPLICABILITY The present invention has biaxiality (biaxial symmetry) in a range where substantially no rainbow-like color spots are generated, or in a range where a rainbow-like color spot is not generated in a viewing angle range required for a liquid crystal display screen. It is preferable that

(Laminated polyester film)
In the present invention, a laminated polyester film mainly used for optical applications is a hard coat made of an electron beam or ultraviolet curable acrylic resin, a siloxane thermosetting resin or the like on the coating layer of the easily adhesive polyester film of the present invention. It is obtained by providing a layer or the like.

It is also a preferable mode to provide a functional layer on the coating layer of the easily adhesive polyester film in the present invention. The functional layer, for the purpose of preventing reflection and glare control, rainbow unevenness control, scratch control, and the like, in addition to the hard coat layer described above, an antiglare layer, an antiglare antireflection layer, an antireflection layer, a low reflection layer and It means a layer having functionality such as an antistatic layer. As the functional layer, various types known in the art can be used, and the type thereof is not particularly limited. Hereinafter, each functional layer will be described.

  For example, for forming the hard coat layer, a known hard coat layer can be used, and it is not particularly limited, but is polymerized by irradiation with any of drying, heat, chemical reaction, or electron beam, radiation, and ultraviolet rays, Resin compounds that react and / or react can be used. Examples of such curable resins include melamine-based, acrylic-based, silicone-based, and polyvinyl alcohol-based curable resins, but in view of obtaining high surface hardness or optical design, a photocurable acrylic-based curable resin is used. Resins are preferred. As such an acrylic curable resin, a polyfunctional (meth) acrylate monomer or an acrylate oligomer can be used, and examples of the acrylate oligomer include polyester acrylate, epoxy acrylate, urethane acrylate, and polyacrylate. Examples thereof include ether acrylate type, polybutadiene acrylate type, and silicone acrylate type. A coating composition for forming the optical functional layer can be obtained by mixing a reaction diluent, a photopolymerization initiator, a sensitizer, and the like with these acrylic curable resins.

  The hard coat layer may have an antiglare function (antiglare function) that scatters external light. The antiglare function (antiglare function) is obtained by forming irregularities on the surface of the hard coat layer. At this time, the haze of the film is ideally preferably 0 to 50%, more preferably 0 to 40%, and particularly preferably 0 to 30%. Of course, 0% is ideal, and may be 0.2% or more, or 0.5% or more.

Therefore, the application of the film in the present invention is mainly applied to optical films in general, and is applicable to LCDs such as prism lens sheets, AR (anti-reflection) films, hard coat films, diffusion plates and shatterproof films, and optical devices such as flat TVs and CRTs. It can be suitably used for a base film of a member, a near-infrared absorption filter that is a member for a front plate for a plasma display, a transparent conductive film for a touch panel, electroluminescence, and the like.

  More specifically, the acrylic resin that is cured by electron beams or ultraviolet rays for forming the hard coat layer is one having an acrylate-based functional group, and, for example, a polyester resin, a polyether resin, or an acrylic resin having a relatively low molecular weight. , Epoxy resin, urethane resin, alkyd resin, spiro acetal resin, polybutadiene resin, polythiol polyene resin, polyfunctional compound such as polyhydric alcohol (meth) acrylate oligomer or prepolymer and ethyl (meth) as a reactive diluent Monofunctional and polyfunctional monomers such as acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, and N-vinylpyrrolidone, for example, trimethylolpropane tri (meth) acrylate, hexanediol (meth) actuate. Rate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol The thing containing di (meth) acrylate etc. can be used.

  However, in the case of an electron beam or an ultraviolet curable resin, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetramethylthylium monosulfide, thioxanthone as photopolymerization initiators in the above resins. And n-butylamine, triethylamine, tri-n-butylphosphine, etc. can be mixed and used as a photosensitizer.

  The silicone-based (siloxane-based) thermosetting resin can be produced by subjecting an organosilane compound to a single or a mixture of two or more in the presence of an acid or base catalyst, followed by a hydrolysis and condensation reaction. In particular, in the case of low reflection, it is more preferable to mix one or more fluorosilane compounds for hydrolysis and condensation reaction in order to improve low refractive index and stain resistance.

(Production of laminated polyester film)
The method for producing the laminated polyester film in the present invention will be described by taking the easily adhesive polyester film as an example, but the present invention is not limited to this.

  The electron beam or ultraviolet ray curable acrylic resin or siloxane thermosetting resin is coated on the coating layer surface of the easily adhesive polyester film. When the coating layer is provided on both sides, the coating is applied to at least one coating layer surface. The coating solution does not need to be particularly diluted, but there is no particular problem even if it is diluted with an organic solvent according to the viscosity, wettability, coating film thickness, etc. of the coating solution. The coating layer is obtained by applying the coating solution to the above-mentioned film and then drying it if necessary, and then curing the coating layer by irradiating and heating an electron beam or an ultraviolet ray in accordance with the curing conditions of the coating solution. Forming a hard coat layer.

  In the present invention, the hard coat layer preferably has a thickness of 1 to 15 μm. When the thickness of the hard coat layer is 1 μm or more, the effects on the chemical resistance, scratch resistance, antifouling property, etc. of the hard coat layer are efficiently exhibited, which is preferable. On the other hand, when the thickness is 15 μm or less, the flexibility of the hard coat layer is maintained and cracks and the like are not likely to occur, which is preferable.

  As for the scratch resistance, it is preferable that the scratches are not visually noticeable when the coated surface is abraded with a black mount. If the scratches are not noticeable in the above evaluation, scratches are less likely to occur when passing through the guide roll, which is preferable from the viewpoint of handleability and the like.

  The lower limit of the coefficient of static friction (μs) is preferably 0.3, and if it is 0.3 or more, there is no problem of excessive slippage, so winding up with a hard chrome plated roll or the like becomes easy in the manufacturing process. It is preferable because the handling property and the blocking resistance are maintained. The upper limit of the coefficient of static friction (μs) is preferably 0.5, and when it is 0.5 or less, there is no risk of scratching the film which is the contacting surface during winding, which is preferable.

  The lower limit of the dynamic friction coefficient (μd) is preferably 0.4, and when it is 0.4 or more, there is no problem of excessive slippage, and therefore winding in a hard chrome plated roll or the like becomes easy in the manufacturing process. It is preferable because the handling property and the blocking resistance are maintained. The upper limit of the dynamic friction coefficient (μd) is preferably 0.6, and it is preferably 0.6 or less so that there is no risk of scratching the film which becomes the contacting surface during winding.

Since the polyester film in the present invention is mainly used as an easily adhesive film for optics, it preferably has high transparency. The lower limit of haze is ideally 0%, and the closer to 0%, the more preferable. The upper limit of haze is preferably 2%, and is preferably 2% or less because the light transmittance is good and a clear image can be obtained in a liquid crystal display device. The haze of the polyester film can be measured, for example, according to the method described below.

  Regarding the adhesion between the coating layer having an easily adhesive layer property and the hard coat layer, the lower limit is preferably 80%, and the upper limit is preferably 100%, as evaluated by the measurement method described below. When it is 80% or more, it can be said that the adhesiveness between the coating layer and the hard coat layer is sufficiently maintained.

  Regarding the adhesiveness between the easy-adhesion layer and the hard coat layer evaluated according to the method described below under high temperature and high humidity conditions, the lower limit is preferably 10%, and the upper limit of the high temperature and high humidity adhesiveness is preferably 100%. is there. When it is 10% or more, the adhesion between the easy-adhesion layer and the hard coat layer is satisfied once under high temperature and high humidity conditions, and the passage property in the post-processing step is satisfied generally. More preferably, it is 50% or more.

  It is preferable that the polyester film for protecting a polarizer formed with a hard coat is not capable of confirming interference spots by the evaluation method described later, and if the interference spots cannot be confirmed by the evaluation method, the visibility of the liquid crystal image device is good. preferable.

The easily adhesive polyester film of the present invention can be used for various purposes, but is preferably used in a manufacturing process of a polarizing plate used for a liquid crystal display device, and particularly preferably used as a protective film of a polarizer constituting the polarizing plate. It is what is done. Usually, most of the polarizers are made of polyvinyl alcohol, and the easily-adhesive polyester film of the present invention is adhered to the polarizer by using an adhesive made of polyvinyl alcohol or a cross-linking agent added thereto as necessary. In that case, it is more preferable that the coating layer of the easily adhesive polyester film of the present invention is used not on the surface on the side to be bonded to the polarizer but on the opposite surface. The surface of the easily-adhesive polyester film of the present invention, which is bonded to the polarizer, contains, for example, a polyester-based resin, a polyvinyl alcohol-based resin, and a crosslinking agent as described in WO 2012/105607. It is preferred that the layers are laminated.

  Next, the present invention will be described in detail with reference to Examples, Comparative Examples and Reference Examples, but the present invention is not limited to the following Examples. The evaluation method used in the present invention is as follows.

(1) Average particle size [measurement method by scanning electron microscope]
The average particle size of the above particles can be measured by the following method. The particles are photographed by a scanning electron microscope (SEM), and the maximum diameter of 300 to 500 particles (between the two most distant points) is magnified at a magnification such that the size of one of the smallest particles is 2 to 5 mm. The distance) is measured, and the average value is taken as the average particle size. The average particle size of the particles present in the coating layer in the present invention can be measured by the measuring method.

[Dynamic light scattering method]
The average particle size of the particles can also be determined by the dynamic scattering method at the time of producing the particles or the film. The sol was diluted with a dispersion medium, measured with a submicron particle analyzer N4 PLUS (manufactured by Beckman Coulter, Inc.) using the parameters of the dispersion medium, and the average particle diameter was obtained by calculating with the cumulant method. In the dynamic light scattering method, the average particle size of particles in the sol is observed, and when the particles are aggregated, the average particle size of the aggregated particles is observed.

(2) Refractive index of particles
The refractive index of particles can be measured by the following method. After drying the inorganic particles at 150 ° C and crushing them in a mortar, immerse the powder in Solvent 1 (having a lower refractive index than the particles), and then add Solvent 2 (having a higher refractive index than the particles) little by little. Was added until. The refractive index of this liquid was measured using an Abbe refractometer (Abbe refractometer manufactured by Atago Co., Ltd.). The measurement was performed at 23 ° C. and D line (wavelength 589 nm). As the solvent 1 and the solvent 2, those which can be mixed with each other are selected, and depending on the refractive index, for example, 1,1,1,3,3,3-hexafluoro-2-propanol, 2-propanol, chloroform, tetrachloride. Solvents such as carbon, toluene, glycerin and the like can be mentioned.

(3) Haze of Easy-Adhesive Polyester Film The haze of the easily-adhesive polyester film was measured using a turbidimeter (NDH2000 manufactured by Nippon Denshoku Co., Ltd.) according to JIS K 7136: 2000.

(4) Adhesion The hard coat layer described in the item of forming the hard coat layer was formed on the easy-adhesion layer of the polyester film obtained in the example. A polyester film for easy adhesion having a hard coat is adhered to the hard coat layer and the base film in conformity with the description in 8.5.1 of JIS-K5400-1990.

Specifically, using a cutter guide with a gap of 2 mm, 100 square-shaped cuts that penetrate the hard coat layer and reach the base film are made on the hard coat layer surface. Then, a cellophane adhesive tape (Nichiban, No. 405; 24 mm width) is attached to the cut surface of the grid and rubbed with an eraser to completely adhere it. Then, vertically peel the cellophane adhesive tape from the hard coat layer surface of the hard coat laminated polarizer protective film, visually count the number of squares peeled from the hard coat layer surface of the hard coat laminated polarizer protective film, the following formula Then, the adhesion between the hard coat layer and the base film is obtained. It should be noted that those that are partially peeled off in the squares are counted as peeled squares.
Adhesion (%) = {1- (number of peeled squares / 100)} × 100

(5) Improvement of interference fringes (iris-like color)
A hard coat layer was formed on the easy adhesion layer of the optical easy adhesion polyester film obtained in each example. The easily adhesive polyester film for optics on which a hard coat was formed was cut into an area of 10 cm (film width direction) × 15 cm (film longitudinal direction) to prepare a sample film. A black glossy tape (Nitto Denko KK, vinyl tape No21; black) was attached to the surface of the obtained sample film opposite to the hard coat layer surface. With the hard coat surface of this sample film as the upper surface, a three-wavelength daylight white (National Palook, FL 15EX-N 15W) is used as the light source, and the position where the strongest reflection can be visually observed from diagonally above (the distance from the light source is 40 ~ It was observed at 60 cm and an angle of 15 to 45 °.

The results of visual observation are ranked according to the following criteria. In addition, the observation is carried out by 5 persons who are familiar with the evaluation, and the highest rank is the evaluation rank. If two ranks have the same number, the center of the three ranks is adopted. For example, if ◎ and ○ are each 2 people and △ is 1 person, ○, if ◎ is 1 person and ○ and △ are 2 people respectively, ○, ◎ and △ are 2 people each and ○ is 1 In the case of first name, ○ is adopted.
◎: No iris-like color is observed even when observed from any angle ○: Slight iris-like color is seen at a certain angle △: Slight iris-like color is observed ×: Clear iris-like color is observed Be done

(6) Blocking resistance The two laminated films were laminated so that the coated surfaces face each other, a load of 5 kg / cm ² was applied, and this was left for 24 hours in an atmosphere of 50 ° C. The superposed films were peeled off, and the peeled state was judged according to the following criteria.
⊚: Lightly peelable ○: There is resistance during peeling, but the coating layer does not transfer to the mating surface.
Δ: Peeling noise was generated and the coating layer was partially transferred to the mating surface
X: Two films adhered and could not be peeled, or the base film was cleaved even if peeled.

(7) Glass transition temperature According to JIS K7121-1987, using a differential scanning calorimeter (manufactured by Seiko Instruments, DSC6200), 10 mg of a resin sample was heated at a temperature of 20 to 300C over a temperature range of 25 to 300C. The extrapolated glass transition onset temperature obtained from the DSC curve was defined as the glass transition temperature.

(8) Number average molecular weight 0.03 g of resin is dissolved in 10 ml of tetrahydrofuran, GPC-LALLS apparatus low angle light scattering photometer LS-8000 (manufactured by Tosoh Corporation, tetrahydrofuran solvent, reference: polystyrene), column temperature 30 ° C., The number average molecular weight was measured using a column (SHODEX KF-802, 804, 806 manufactured by Showa Denko KK) at a flow rate of 1 ml / min.

(9) Resin composition A resin was dissolved in deuterated chloroform, 1H-NMR analysis was performed using a nuclear magnetic resonance analyzer (NMR) Gemini-200 manufactured by Varian, and the mol% ratio of each composition was determined from the integral ratio. did.

(Polymerization of polyester resin)
Polymerization of Copolymerized Polyester Resins (B1) to (B3) for Coating Layer In a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux type cooler, 342.0 parts by mass of dimethyl 2,6-naphthalenedicarboxylate, Dimethyl terephthalate 35.0 parts by mass, dimethyl-5-sodium sulfoisophthalate 35.5 parts by mass, ethylene glycol 198.6 parts by mass, 1,6-hexanediol 118.2 parts by mass, and tetra-n-butyl titanate 0.1. 4 parts by mass were charged and the transesterification reaction was carried out from 160 ° C. to 220 ° C. for 4 hours. Further, 60.7 parts by mass of sebacic acid was added to carry out an esterification reaction. Next, the temperature was raised to 255 ° C., the pressure of the reaction system was gradually reduced, and the reaction was performed under reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolyester resin (B1). The obtained copolyester resin was light yellow and transparent.
The composition of the copolyester resin (B1) is as shown in Table 1.
In addition, copolymerized polyester resins (B2) and (B3) having the compositions shown in Table 1 were obtained in the same manner by changing the raw materials.

(Production of polyester aqueous dispersion)
30 parts by mass of the copolymerized polyester resin (B1) and 15 parts by mass of ethylene glycol-n-butyl ether were placed in a reactor equipped with a stirrer, a thermometer and a reflux device, and heated at 110 ° C. and stirred to dissolve the resin. After the resin was completely dissolved, 55 parts by mass of water was gradually added to the polyester solution with stirring. After the addition, the liquid was cooled to room temperature with stirring to prepare a milky white polyester aqueous dispersion (Bw1) having a solid content of 25% by mass.
Similarly, a polyester aqueous dispersion Bw2 was obtained from the copolymerized polyester resin B2, and a polyester aqueous dispersion Bw3 was obtained from the copolymerized polyester resin B3.

(Production of polyurethane water dispersion)
Polymerization of Water-Soluble Polyurethane Resin (A1) Containing Aliphatic Polycarbonate Polyol As a 4-neck flask equipped with a stirrer, Dimroth condenser, nitrogen introduction tube, silica gel drying tube, and thermometer, 4,4- 43.75 parts by mass of diphenylmethane diisocyanate, 12.85 parts by mass of dimethylolbutanoic acid, 153.41 parts by mass of polyhexamethylene carbonate diol having a number average molecular weight of 2000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent. Then, the mixture was stirred under a nitrogen atmosphere at 75 ° C. for 3 hours, and it was confirmed that the reaction solution reached a predetermined amine equivalent. Next, this reaction liquid was cooled to 40 ° C., and then 8.77 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, the temperature was adjusted to 25 ° C., and the polyurethane prepolymer solution was added and dispersed in water while stirring and mixing at 2000 min ⁻¹ . . Then, acetone and a part of water were removed under reduced pressure to prepare a water-soluble polyurethane resin (A1) having a solid content of 37% by mass. The glass transition temperature of the obtained polyurethane resin was -30 ° C.

Polymerization of Water-Soluble Polyurethane Resin (A2) Containing Aliphatic Polycarbonate Polyol 38.41 parts by mass of isophorone diisocyanate, 6.95 parts by mass of dimethylolpropanoic acid, polyhexamethylene carbonate diol 158.99 having a number average molecular weight of 2000. A water-soluble polyurethane resin (A2) was prepared in the same manner as in the polymerization of A1 except that the amount of dibutyltin dilaurate was 0.03 part by mass, and the amount of acetone was 84.00 parts by mass.

(Polymerization of block polyisocyanate cross-linking agent)
Stirrer, thermometer, polyisocyanate compound having isocyanurate structure using hexamethylene diisocyanate as a raw material in a flask equipped with a reflux condenser (Asahi Kasei Chemicals, Duranate TPA) 100 parts by mass, propylene glycol monomethyl ether acetate 55 parts by mass, 30 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 750) was charged, and the mixture was kept at 70 ° C. for 4 hours under a nitrogen atmosphere. Then, the temperature of the reaction solution was lowered to 50 ° C., and 47 parts by mass of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction solution was measured, and it was confirmed that the absorption of the isocyanate group had disappeared to obtain a blocked polyisocyanate aqueous dispersion (Cx1) having a solid content of 40% by mass.

(Polymerization of oxazoline crosslinking agent)
A flask equipped with a thermometer, a nitrogen gas introduction tube, a reflux condenser, a dropping funnel, and a stirrer was used, and a mixture of 58 parts by mass of ion-exchanged water and 58 parts by mass of isopropanol as an aqueous medium, and a polymerization initiator (2, 2 4 parts by mass of'-azobis (2-amidinopropane) dihydrochloride) was added. On the other hand, in the dropping funnel, 16 parts by mass of 2-isopropenyl-2-oxazoline as a polymerizable unsaturated monomer having an oxazoline group, methoxypolyethylene glycol acrylate (average number of moles of ethylene glycol added: 9 moles, Shin Nakamura Chemical Co., Ltd. 32 parts by mass) and 32 parts by mass of methyl methacrylate were added, and the mixture was added dropwise at 70 ° C. for 1 hour under a nitrogen atmosphere. After completion of the dropping, the reaction solution was stirred for 9 hours and cooled to obtain a water-soluble resin (Cx2) having an oxazoline group having a solid content concentration of 40% by mass.

(Polymerization of carbodiimide type crosslinking agent)
A flask equipped with a stirrer, a thermometer, and a reflux condenser was charged with 168 parts by mass of hexamethylene diisocyanate and 220 parts by mass of polyethylene glycol monomethyl ether (M400, average molecular weight 400), and stirred at 120 ° C. for 1 hour. 26 parts by mass of 4'-dicyclohexylmethane diisocyanate and 3.8 parts by mass of 3-methyl-1-phenyl-2-phosphoren-1-oxide (2% by mass with respect to all isocyanate) as a carbodiimidization catalyst were added, and 185 under a nitrogen stream was added. Stirred for an additional 5 hours at ° C. The infrared spectrum of the reaction solution was measured, and it was confirmed that the absorption at wavelengths of 2200 to 2300 cm ^-1 had disappeared. After cooling to 60 ° C., 567 parts by mass of ion-exchanged water was added to obtain a carbodiimide water-soluble resin (Cx3) having a solid content of 40% by mass.

(Epoxy cross-linking agent)
As an epoxy-based cross-linking agent, Denacol (registered trademark) EX-521 (solid content concentration 100%) manufactured by Nagase Chemtex Co., Ltd. was used (epoxy-based cross-linking agent (Cx4)).

(Melamine type crosslinking agent)
As a melamine-based cross-linking agent, Beckamine (registered trademark) M-3 (solid content concentration 60%) manufactured by DIC was used (melamine-based cross-linking agent (Cx5)).

(Zirconia particles)
Reference was made to Example 8 of JP-A-2008-290896, and the procedure was as follows.
In a 3 liter glass container, 2283.6 g of pure water and 403.4 g of oxalic acid dihydrate were charged and heated to 40 ° C. to prepare a 10.72 mass% oxalic acid aqueous solution. While stirring this aqueous solution, 495.8 g of zirconium oxycarbonate powder (ZrOCO ₃ , manufactured by AMR International Corp., containing 39.76 mass% in terms of ZrO ₂ ) was gradually added and mixed for 30 minutes. Then, heating was performed at 90 ° C. for 30 minutes. Next, 1747.2 g of a 25.0 mass% tetramethylammonium hydroxide aqueous solution (manufactured by Tama Chemical Industry Co., Ltd.) was gradually added over 1 hour. At this point, the mixed liquid was in a slurry state and contained 4.0% by mass in terms of ZrO ₂ . This slurry was transferred to a stainless steel autoclave container and subjected to hydrothermal treatment at 145 ° C. for 5 hours. The product after the hydrothermal treatment was completely sol-free without deflocculation. The obtained sol contained 4.0% by mass as ZrO ₂ , pH 6.8, and the average particle size by dynamic light scattering method was 19 nm. The transmittance of the sol measured by adjusting the ZrO ₂ concentration to 2.0% by mass with pure water was 88%. When the particles were observed by a transmission electron microscope, most of the aggregated particles of ZrO ₂ primary particles having a size of about 7 nm were found. Using an ultrafiltration device, 4000 g of zirconia sol having a ZrO ₂ concentration of 4.0% by mass obtained by performing the above hydrothermal treatment was washed and concentrated while gradually adding pure water to obtain a ZrO ₂ concentration. 953 g of a zirconia sol having a transmittance of 76% when 13.1% by mass, pH 4.9, and ZrO ₂ concentration of 13.1% by mass was obtained.

After adding 3.93 g of 20 mass% citric acid aqueous solution and 11.0 g of 25 mass% tetramethylammonium hydroxide aqueous solution to 300 g of zirconia sol having ZrO ₂ concentration of 13.1 mass% obtained by performing the above washing and concentration. When further concentrated by an ultrafiltration device, 129 g of high-concentration zirconia sol (Cpz1) having a ZrO ₂ concentration of 30.5 mass% was obtained. The obtained high-concentration zirconia sol had a pH of 9.3 and an average particle diameter of 19 nm measured by a dynamic light scattering method. Further, this zirconia sol had no precipitate and was stable under the condition of 50 ° C. for 1 month or longer.

  Further, Cpz2 having an average particle size of 32 nm was obtained by referring to Example 2 of JP-A-2008-290896, and Cpz3 having an average particle size of 48 nm was obtained by referring to Example 1.

(Titania particles)
With reference to Example 1 of JP2011-132484A, the following procedure was performed.
12.09 kg of an aqueous titanium tetrachloride solution containing titanium tetrachloride (manufactured by Osaka Titanium Technologies Co., Ltd.) in an amount of 7.75 mass% based on TiO _2, and ammonia water containing 15 mass% of ammonia (manufactured by Ube Industries, Ltd.) 4 The mixture was mixed with 0.69 kg to prepare a white slurry liquid having a pH of 9.5. Next, this slurry was filtered and then washed with pure water to obtain 9.87 kg of a hydrous titanic acid cake having a solid content of 10% by mass. Next, to this cake, 11.28 kg of hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Co., Inc.) containing 35% by mass of hydrogen peroxide and 20.00 kg of pure water were added, and then at a temperature of 80 ° C. for 1 hour. Then, the mixture was heated under stirring, and 57.52 kg of pure water was further added to obtain 98.67 kg of an aqueous titanic acid peroxide solution containing 1% by mass of titanic acid peroxide on the basis of TiO ₂ . This aqueous solution of peroxytitanic acid had a transparent yellowish brown color and had a pH of 8.5.

Next, 4.70 kg of a cation exchange resin (manufactured by Mitsubishi Chemical Co., Ltd.) was mixed with 98.67 kg of the aqueous solution of titanic acid peroxide, and potassium stannate (manufactured by Showa Kako Co., Ltd.) was converted into SnO ₂ in this mixture. 12.33 kg of a potassium stannate aqueous solution containing 1% by mass based on the standard was gradually added with stirring. Next, after separating the cation exchange resin incorporating potassium ions and the like, the cation exchange resin was placed in an autoclave (manufactured by Pressure Resistant Glass Industry Co., Ltd., 120 L) and heated at a temperature of 165 ° C. for 18 hours.

Next, after cooling the obtained mixed aqueous solution to room temperature, it was concentrated with an ultrafiltration membrane device (ACV-3010 manufactured by Asahi Kasei Corp.) to obtain titanium-based fine particles (solid content 10% by mass). Hereinafter, 9.90 kg of an aqueous dispersion sol (Cpt1) containing "P-1" was obtained. When the solid matter contained in the sol thus obtained was measured by the above method, it was found to be titanium-based fine particles (primary particles) having a rutile-type crystal structure and composed of a composite oxide containing titanium and tin. It was Furthermore, when the content of the metal component contained in the titanium-based fine particles was measured, based on the oxide conversion standard of each metal component, TiO _{2 was} 87.2 mass%, SnO _{2 was} 11.0 mass%, and K ₂ O. It was 1.8% by mass. The pH of the mixed aqueous solution was 10.0. Furthermore, the water-dispersed sol containing the titanium-based fine particles has a transparent milky white color, and the titanium-based fine particles contained in the water-dispersed sol have an average particle diameter of 35 nm by a dynamic light scattering method, and particles having a particle size of 100 nm or more. The distribution frequency of coarse particles having a diameter was 0%. Furthermore, the refractive index of the obtained titanium-based fine particles could be considered to be 2.42.
Further, Cpt2 having an average particle size of 32 nm was obtained by referring to Example 2 of JP-A-2011-132484, and Cpt3 having an average particle size of 42 nm was obtained by referring to Example 4.

(Zirconia / titania mixed particles)
By mixing the zirconia particles (Cpz1) and the titania particles (Cpt1) obtained above in a mass ratio of 75/25, a zirconia / titania mixed particle having a solid content concentration of 13 mass% ((Cp1): average particle size 23 nm) It was created.
Similarly, Cpz2 and Cpt2 to Cp2 (average particle size 32 nm) and Cpz3 and Cpt3 to Cp3 (average particle size 46 nm) were obtained.

(Ceria particles)
An experiment was conducted as follows with reference to JP-A-2011-132107.
216 g of cerium (III) chloride heptahydrate was added to 10 L of distilled water and stirred to dissolve. The temperature was raised to 93 ° C. while continuing stirring, and 5.6 kg of 1.0% aqueous sodium hydroxide solution was added all at once. After further stirring at 93 ° C for 6 hours, the mixture was cooled to 25 ° C to obtain a white precipitate.
The precipitate was separated by a centrifuge, 15 L of distilled water was added to the obtained precipitate, the mixture was stirred and redispersed, and then the precipitate was separated by a centrifuge. This operation was performed 3 times in total to wash the precipitate.
Distilled water was added to the obtained precipitate to adjust the pH to 9.2 and dispersed by an ultrasonic disperser to obtain a ceria particle dispersion (Cp4) having a solid content concentration of 12% by mass. The average particle diameter measured by the dynamic light scattering method was 34 nm.

(Formation of hard coat layer)
A coating liquid for forming a hard coat layer having the following composition was applied to a surface of the polyester film manufactured in Examples described later, which is opposite to the surface to be bonded to the polarizer, using a # 10 wire bar, and the coating liquid was applied at 70 ° C. for 1 minute. It was dried and the solvent was removed. Then, the film coated with the hard coat layer was irradiated with ultraviolet rays of 300 mJ / cm ² using a high pressure mercury lamp to obtain a polarizer protective film having a hard coat layer having a thickness of 5 μm.
・ Coating liquid for forming hard coat layer Methyl ethyl ketone 65.00% by mass
Dipentaerythritol hexaacrylate 27.20 mass%
(Shin-Nakamura Chemical A-DPH)
Polyethylene diacrylate 6.80 mass%
(Shin-Nakamura Chemical A-400)
Photopolymerization initiator 1.00% by mass
(Irgacure 184 manufactured by Ciba Specialty Chemicals)

(Example 1)
Coating liquid raw material / particle A aqueous dispersion: zirconia / titania mixed particles (Cp1) with an average particle size of 23 nm
(Amount of zirconia in zirconia / titania 75% by mass, solid content concentration 13% by mass)
Particle A water dispersion: silica sol having an average particle size of 450 nm (solid content concentration 4% by mass)
・ Polyester water dispersion ((Bw1), solid content concentration 25 mass%)
・ Polyurethane water dispersion ((A1), solid content concentration 37 mass%)
・ Blocked isocyanate cross-linking agent ((Cx1), solid content concentration 40% by mass)

(1) Preparation of coating liquid for easy-adhesion layer A coating liquid having the following composition was prepared.
Water 36.00 parts by mass Isopropyl alcohol 30.31 parts by mass Particle A water dispersion 10.99 parts by mass Particle B water dispersion 0.91 parts by mass Polyester water dispersion 8.80 parts by mass Polyurethane water dispersion 3.96 parts by mass Parts Blocked isocyanate cross-linking agent 5.50 parts by mass High boiling point solvent (NMP) 3.00 parts by mass Surfactant (fluorine-based, solid content concentration 10% by mass) 0.25 parts by mass

(2) Production of easily-adhesive polyester film PET resin pellets having an intrinsic viscosity (solvent: phenol / tetrachloroethane = 60/40) of 0.62 dl / g and containing substantially no particles as a film raw material polymer It was dried at 135 ° C. for 6 hours under a reduced pressure of 133 Pa. Then, it supplied to the extruder, melt-extruded into a sheet form at about 280 ° C., and rapidly cooled and adhered to solidify on a rotating cooling metal roll kept at a surface temperature of 20 ° C. to obtain an unstretched PET sheet.

  This unstretched PET sheet was heated to 100 ° C. by a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction by roll groups having different peripheral speeds to obtain a uniaxially stretched PET film.

  Then, the coating liquid was applied to one side of the PET film by a roll coating method, and then dried at 80 ° C. for 15 seconds. The coating amount after drying after the final stretching was adjusted to 0.12 g / m 2. Then, with a tenter, the film was stretched 4.0 times in the width direction at 150 ° C., the film was fixed in the width direction, heated at 230 ° C. for 0.5 seconds, and further heated at 230 ° C. for 10 seconds 3 % Relaxation treatment in the width direction was performed to obtain an optical adhesion polyester film having a thickness of 38 μm. The polyurethane resin component, the polyester resin component, and other components in the coating layer are 20% by mass, 30% by mass, and 50% by mass, respectively, as shown in Table 2.

(Examples 2, 3, 18 to 25, Comparative Examples 1 to 7)
An easily-adhesive polyester film was obtained in the same manner as in Example 1 except that the ratios of the polyurethane resin component, the polyester resin component and the other components in the coating layer were set to Table 2 or 3.

(Examples 4 to 7)
An easily adhesive polyester film was obtained in the same manner as in Example 1 except that the cross-linking agent of the coating liquid was changed and the composition of each component in the coating layer was changed as shown in Table 2.

(Examples 8 to 12)
An easily adhesive polyester film was obtained in the same manner as in Example 1 except that the type of the particles A of the coating liquid was changed and the composition of each component in the coating layer was changed as shown in Table 2.

(Examples 13 to 15)
An easily-adhesive polyester film was obtained in the same manner as in Example 1 except that the thickness of the coating layer was changed as shown in Table 2.

(Examples 16 and 17)
An easily adhesive polyester film was obtained in the same manner as in Example 1 except that the amount of particles B in the coating layer was changed as shown in Table 2.

(Examples 26 and 27)
An easily-adhesive polyester film was obtained in the same manner as in Example 1 except that the type of the copolymerized polyester resin component was changed as shown in Table 3.

(Example 28)
An easily-adhesive polyester film was obtained in the same manner as in Example 1 except that the type of polyurethane resin component was changed as shown in Table 3.

  The respective results are shown in Tables 2 and 3. The plots on the triangular chart of each of the examples and comparative examples are shown in FIG.

(Static friction coefficient, dynamic friction coefficient (μs, μd))
Incidentally, the friction coefficient of the polyester film obtained in Examples, Comparative Examples is measured according to JIS K7125-1999 plastic-film and sheet friction coefficient test method, using Tensilon (Toyo Baldwin, RTM-100), Each film had a static friction coefficient (μs) of 0.35 to 0.5 and a dynamic friction coefficient (μd) of 0.45 to 0.6, and there was no problem in winding property and handling property. .

According to the present invention, it is possible to suppress rainbow unevenness, low interference, transparency, blocking resistance, excellent adhesion to various functional layers, and excellent slidability, and easy adhesion that can be suitably used in optical applications, particularly polarizer protective film applications. It has become possible to provide a method for producing a polyester film and a laminated polyester film using the above.

P1: a straight line Q1 passing through the coordinates (10, 55, 35) and (10, 10, 80): a straight line R1 passing through the coordinates (10, 10, 80) and (70, 10, 20): a coordinate (70, 10, 20) and (50, 40, 10) passing straight line S1: Coordinates (45, 45, 10) and (10, 55, 35) passing straight line ◯: Plot of each example □: Comparative example Numerical values in the plot triangle chart: Number of each Example or each Comparative Example

Claims (5)

Polyurethane resin having a polycarbonate skeleton, a coating layer containing a polyester resin having a naphthalene skeleton is provided on at least one surface of the polyester film, and the content of the polyurethane resin component when the total solid content of the coating layer is 100% by mass (mass) %) Is a, the content (% by mass) of the polyester resin component having a naphthalene skeleton is b, and the total amount (% by mass) of the components other than these is c in a triangular chart, where a, b, and c are straight lines. A method for producing an easily adhesive polyester film in a region surrounded by four straight lines P1, a straight line Q1, a straight line R1, and a straight line S1, wherein the easy adhesive polyester film adopts an in-line coating method as a coating method. Manufacturing method .
Here, the straight line P1, the straight line Q1, the straight line R1, and the straight line S1 are as follows.

Straight line P1: a straight line Q1 passing through a point where a is 10 mass%, b is 55 mass% and c is 35 mass% and a point is 10 mass%, b is 10 mass% and c is 80 mass% : A straight line R1: a passing through a point where a is 10% by mass, b is 10% by mass and c is 80% by mass, and a point is 70% by mass, b is 10% by mass and c is 20% by mass. Is 70% by mass, b is 10% by mass, c is 20% by mass, and a straight line S1: a is 45 which passes through a point of 50% by mass of a, 40% by mass of b and 10% by mass of c. A straight line that passes through the points where mass%, b is 45 mass%, c is 10 mass%, and a is 10 mass%, b is 55 mass%, and c is 35 mass%. The method for producing an easily adhesive polyester film according to claim 1, wherein the coating layer contains a crosslinking agent. The method for producing an easily adhesive polyester film according to claim 1, wherein the coating layer contains metal oxide particles (particle A) having a refractive index of 1.7 or more. The method for producing an easily adhesive polyester film according to claim 1, wherein the coating layer contains lubricant particles (particles B). It is selected from the group consisting of a hard coat layer, an antiglare layer, an antiglare antireflection layer, an antireflection layer and a low reflection layer on the coating layer of the easily adhesive polyester film according to any one of claims 1 to 4. A method for producing a laminated polyester film having one or more functional layers according to claim 1.