KR20230157319A - Easily adhesive polyester film - Google Patents

Abstract

[Problem] The present invention is to provide an easily adhesive polyester film that improves the reliability of adhesion to functional layers such as a hard coat layer, and is an easily adhesive polyester film suitable for optical applications, etc. The film is provided.
[Solution] On at least one side of the polyester film, there is an application layer formed by curing a composition containing a polyester having a polycyclic aromatic skeleton and a crosslinking agent having at least one skeleton selected from aliphatic, alicyclic, and heterocyclic. An easily adhesive polyester film, comprising the thickness of the coating layer, the surface free energy of the surface of the coating layer on the side that is not in contact with the polyester film of the coating layer, the nitrogen atom ratio on the surface of the coating layer, and the thickness of the coating layer in the depth direction of the coating layer. An easily adhesive polyester film in which characteristic values related to the nitrogen atom ratio satisfy a specific relationship.

Description

Easily adhesive polyester film

The present invention relates to an easily adhesive polyester film excellent in adhesion to various functional layers, blocking resistance, and transparency. More specifically, it relates to an easily adhesive polyester film that is suitably used also in optical applications.

A hard coat film in which a transparent hard coat layer is laminated is used on the front surface of displays and decorative materials such as touch panels, computers, TVs, and liquid crystal displays. In addition, a transparent polyester film is generally used as a transparent plastic film as a base material, and in order to improve the adhesion between the polyester film as a base material and the hard coat layer, an intermediate layer is applied to the surface of the polyester film. In many cases, a coating layer with easy adhesion is provided.

The above-mentioned hard coat film is required to have durability against temperature, humidity, and light, transparency, chemical resistance, scratch resistance, antifouling property, etc. In addition, since it is often used on the surface of displays or decorative materials, visibility and designability are required. Therefore, in order to suppress glare and iris-like coloring caused by reflected light when viewed from an arbitrary angle, a multi-layer structure in which high refractive index layers and low refractive index layers are alternately laminated on the upper layer of the hard coat layer is used. Installing an anti-reflection layer is also commonly done.

In recent years, hard coat layers having various skeletons have been developed, and the adhesion between the base material and the hard coat layer is discussed each time. In addition to initial adhesion immediately after lamination, reliability for long-term use of LCD TVs using films laminated with a hard coat layer is required, including moisture and heat resistance, adhesion maintenance, and deterioration of adhesion over time, and various evaluations have been conducted. It is required that the product be resistant.

In the field of conventional easily adhesive polyester films, when a polyester resin containing a naphthalenedicarboxylic acid component is used in an easily adhesive coating layer, it has excellent adhesion to the polyester film as a base material, and is proposed as a suitable example. (For example, see Patent Document 1). Additionally, a method of using a polyurethane resin containing a polycarbonate component as a resin with excellent flexibility and high adhesion has been proposed (for example, see Patent Document 2).

However, although adhesion was confirmed for both, an easily adhesive polyester film that ensured adhesion after long-term storage was not obtained.

Japanese Patent Laid-Open No. 2011-246663 Japanese Patent Laid-Open No. 2011-168053

The present invention was made against the background of these problems of the prior art. That is, the purpose of the present invention is to provide an easily adhesive polyester film with improved reliability of adhesion to functional layers such as a hard coat layer, and to provide an easily adhesive polyester film suitable for optical applications, etc. It's in the thing.

The present inventor has arrived at the present invention as a result of intensive studies to achieve this objective.

That is, the present invention has the following configuration.

1. Easy adhesion having, on at least one side of a polyester film, an application layer formed by curing a composition containing polyester having a polycyclic aromatic skeleton and a crosslinking agent having at least one skeleton selected from aliphatic, alicyclic, and heterocyclic groups. As a polyester film,

The thickness (d: nm) of the application layer satisfies the following equation (1),

The surface free energy (γ _s : mN/m) of the surface of the coating layer that is not in contact with the polyester film of the coating layer satisfies the following equation (2),

According to X-ray photoelectron spectroscopy (ESCA), the nitrogen atom ratio (A _N : at%) on the surface of the coating layer satisfies the following equation (3),

In the distribution curve of _the nitrogen element based on element distribution measurement in the depth direction, the maximum value of the nitrogen atom _ratio (A _N : at%) and the time t ₂ (seconds) at which the median value of A _N Y (A _N Z: at %) (t ₂ /t ₁ ) satisfies the following equation (4). Polyester film.

30≤d≤200 … Equation (1)

43≤γ _s≤49 … Equation (2)

3.0≤A _N≤9.5 ... Equation (3)

(t ₂ /t ₁ )×100≥40 … Equation (4)

2. The adhesion

The adhesion Easy-adhesive polyester film.

X-Y(%)≤5... Equation (5)

3. The easily adhesive polyester film according to the first or second item, wherein the polyester having a polycyclic aromatic skeleton is a polyester having a naphthalene skeleton.

4. In any of the first to third clauses above, the crosslinking agent having at least one skeleton selected from aliphatic, alicyclic, and heterocyclic is an isocyanate crosslinking agent having at least one skeleton selected from aliphatic, alicyclic, and heterocyclic. The easily adhesive polyester film described.

According to the present invention, an easily adhesive polyester film that ensures adhesion reliability after long-term storage with a functional layer such as a hard coat layer can be provided, and its application to optical applications and the like becomes widely possible.

Figure 1 is an example of a distribution curve of nitrogen element based on element distribution measurement etched in the depth direction from the surface of the coating layer by ESCA for the easily adhesive polyester film of the present invention.
Figure 2 is an example of a distribution curve of nitrogen element based on element distribution measurement etched in the depth direction from the surface of the coating layer by ESCA for the easily adhesive polyester film of Example 1.

(polyester film)

The polyester film used as a base material in the present invention is a film mainly composed of polyester resin. Here, “a film mainly composed of polyester resin” means a film formed from a resin composition containing 50% by mass or more of polyester resin. When mixed with other polymers (e.g., polycarbonate resin, polyimide resin, etc.), it means containing 50% by mass or more of polyester resin, and when copolymerized with other monomers, it means containing polyester structural units. It means containing 50 mol% or more. Preferably, the polyester film contains 90% by mass or more of polyester resin, more preferably 95% by mass or more, and even more preferably 100% by mass.

The material of the polyester resin is not particularly limited, but a copolymer formed by polycondensation of a dicarboxylic acid component and a diol component, or a mixed resin thereof can be used. Dicarboxylic acid components include, for example, terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, Diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid , hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, blood Examples include melic acid, azelaic acid, dimer acid, sebacic acid, suberic acid, and dodecanedicarboxylic acid.

Diol components constituting the polyester resin include, for example, ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and decamethylene glycol. , 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl) Sulfone, etc. can be mentioned.

The dicarboxylic acid component and diol component that constitute the polyester resin may be used singly or in combination of two or more. Additionally, other acid components such as trimellitic acid and other hydroxyl components such as trimethylolpropane may be added as appropriate.

Specific examples of the polyester resin include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Among these, polyethylene terephthalate is preferable in terms of the balance between physical properties and cost. In addition, in order to control optical properties such as polarization, it is also preferable to include other copolymerization components or other polymers. Preferred copolymerization components from the viewpoint of controlling the optical properties of the polyester film include diethylene glycol and a copolymerization component having norbornene in the side chain.

In order to improve the handling properties such as slipperiness and windability of polyester films, inert particles may be included in the film. However, in order to maintain high transparency, it is preferable that the content of inert particles in the film is as small as possible. do. Therefore, it is preferable to have a multilayer structure in which particles are contained only in the surface layer of the film, or to contain particles only in the coating layer laminated on at least one side of the polyester film without substantially containing particles in the film.

In addition, “substantially containing no particles” means, for example, in the case of inorganic particles, when the elements derived from the particles are quantitatively analyzed by fluorescence X-ray analysis, it is 50 ppm or less, preferably 10 ppm or less, most preferably means the content below the detection limit. This means that even if particles are not actively added to the base film, contaminants derived from foreign substances, raw material resin, or contaminants attached to the lines or equipment during the film manufacturing process are peeled off and inevitably mixed into the film. Because there are cases where it happens.

In addition, when the polyester film is made into a multilayer structure, a two-type three-layer structure in which the inner layer contains substantially no inert particles and only the outermost layer contains inert particles is preferable because it is possible to achieve both transparency and processability. do.

The polyester film serving as the substrate may be a single layer or a lamination of two or more types of layers. Additionally, as long as it is within the range showing the effect of the present invention, various additives can be contained in the film as needed. Examples of additives include antioxidants, lightfasters, anti-gelling agents, organic wetting agents, antistatic agents, ultraviolet absorbers, and surfactants. When the film has a laminated structure, it is also preferable to contain additives depending on the function of each layer as needed. For example, in order to prevent light deterioration of the polarizer, it is also desirable to add an ultraviolet absorber or the like to the inner layer.

Polyester films can be manufactured according to conventional methods. For example, it can be obtained by melting and extruding the above-described polyester resin into a film form and cooling and solidifying it with a casting drum to form a film. As the polyester film in the present invention, either an unstretched film or a stretched film can be used, but a stretched film is preferable in terms of durability such as mechanical strength and chemical resistance. When the polyester film is a stretched film, the stretching method is not particularly limited, and includes longitudinal uniaxial stretching, transverse uniaxial stretching, vertical and horizontal sequential biaxial stretching, and longitudinal and transverse simultaneous biaxial stretching, etc. can be employed. When stretching a polyester film, stretching may be performed before laminating the easily adhesive coating layer described later, or may be performed after laminating the easily adhesive coating layer. It is also possible to uniaxially stretch in the longitudinal or transverse direction before laminating the easily adhesive coating layer, and to stretch in the other direction after laminating the coating layer.

(Application layer)

The easily adhesive polyester film of the present invention is one in which an easily adhesive application layer is laminated on a base film made of polyester as described above. The application layer contains binder resin and additives.

Hereinafter, each composition of the application layer will be described in detail.

The binder resin constituting the application layer is a resin having easy adhesiveness, and from the viewpoint of particle retention and adhesion, polyester is suitable, and in the present invention, polyester having a polycyclic aromatic skeleton is optimal. This is compatible with the composition of the hard coat layer described later, but is also suitable from the viewpoint of conjugate interaction when the composition of the hard coat layer has an aromatic skeleton.

Specific examples of polyester having a polycyclic aromatic skeleton include polyester having a naphthalene skeleton, polyester having a fluorene skeleton, polyester having an anthracene skeleton, and polyester having a phenanthrene skeleton.

In the present invention, it is preferable that the binder resin constituting the application layer does not contain urethane resin. Urethane resin is sometimes used from the viewpoint of elasticity or isomerism of the coating film, but it is obvious that urea compounds are mixed as impurities by the urethane resin, and the amount of urea compounds present in the coating layer is too large. From the viewpoint of maintaining stability over time of adhesion to the ground, it is preferable not to contain urethane resin.

The polyester is preferably contained in an amount of 10% by mass or more and 90% by mass or less in the solid content of all resins and crosslinking agents contained in the composition for forming an application layer. More preferably, it is 15% by mass or more and 85% by mass or less. When the polyester resin content is 90% by mass or less, adhesion to functional layers such as hard coat layers under high temperature and high humidity is maintained, which is preferable. Conversely, if the content is 10% by mass or more, adhesion to the polyester base film at room temperature and under high temperature and high humidity is easy to maintain, which is preferable.

In the present invention, it is preferable to contain a crosslinking agent in order to form a crosslinked structure in the application layer. And, the cross-linking agent is preferably a cross-linking agent having at least one skeleton selected from aliphatic, alicyclic, and heterocyclic groups. Additionally, a cross-linking agent capable of producing a urea group through a side reaction of cross-linking is suitable, and specific cross-linking agents include an isocyanate-based cross-linking agent and a carbodiimide-based cross-linking agent. Among these, an isocyanate crosslinking agent is suitable for its effectiveness in improving the stability of the coating solution over time and adhesion under high temperature and high humidity treatment. In addition, in the present invention, isocyanate having at least one skeleton selected from aliphatic, alicyclic, and heterocyclic is optimal. Additionally, in order to promote the crosslinking reaction, a catalyst or the like can be appropriately used in the composition for forming the coating layer as needed.

Specific examples of aliphatic isocyanate include 1,4-diisocyanatobutane, 1,5-pentamethylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1 ,12-Dodecane diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 3,5,5-trimethyl- 1,6-hexamethylene diisocyanate, etc. are mentioned.

Specific examples of alicyclic isocyanate include cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3-bis(isocyanate methyl)cyclohexane, and 1,4-bis(isocyanate). Methyl)cyclohexane, cyclohexyl 1,4-diisocyanate, 1,1-bis(isocyanatomethyl)cyclohexane, 2,4-hexahydrotoluylene diisocyanate, 2,6-hexahydrotoluylene diisocyanate etc. can be mentioned.

Specific examples of heterocyclic isocyanates include 2,5-diisocyanatothiophene, 2,5-bis(isocyanatomethyl)thiophene, 2,5-diisocyanatotetrahydrothiophene, and 2,5-diisocyanatothiophene. -bis(isocyanatomethyl)tetrahydrothiophene, 3,4-bis(isocyanatomethyl)tetrahydrothiophene, 2,5-diisocyanato-1,4-dithiane, 2,5 -bis(isocyanatomethyl)-1,4-dithiane, 4,5-diisocyanato-1,3-dithiolane, 4,5-bis(isocyanatomethyl)-1,3- Dithiolane, 4,5-bis(isocyanatomethyl)-2-methyl-1,3-dithiolane, 2,6-di(isocyanatemethyl)furan, 5,5'-methylenebisfurfuryl isocyanate, 5 , 5'-Isopropylidenebisfurfuryl isocyanate, or 2,4,6-trioxohexahydro-1,3,5-tri, which is a trimer of diisocyanates and has a triazine ring called an isocyanurate form. Azine-1,3,5-triyltris(6,1-hexanediyl)trisisocyanate, 1,3,5-tris[(5-isocyanato-1,3,3-trimethylcyclohexyl)methyl] -1,3,5-triazine-2,4,6(1H,3H,5H)-trione, etc.

In the present invention, isocyanate having an aromatic skeleton is highly reactive, so it easily reacts with moisture in the air and promotes the production of urea compounds more than necessary, so it is preferable not to include it in the composition for forming a coating layer. do. Also, from the viewpoint of weather resistance, it is preferable that it is an isocyanate having at least one skeleton among aliphatic, alicyclic, and heterocyclic groups. In addition, in the present application, blocked isocyanates can also be used similarly, and especially when the coating agent is water-based, it is particularly preferable from the viewpoint of suppressing the production of urea compounds.

Blocking agents include bisulfite-based compounds such as soda bisulfite, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 4-nitro-3,5-dimethyl. Pyrazole-based compounds such as pyrazole, phenol-based compounds such as phenol and cresol, aliphatic alcohol-based compounds such as methanol and ethanol, active methylene-based compounds such as dimethyl malonate and acetylacetone, and mercaptan-based compounds such as butyl mercaptan and dodecyl mercaptan. , acid amide series such as acetanilide and acetic acid amide, lactam series such as ε-caprolactam and δ-valerolactam, acid imide series such as succinic acid imide and maleic acid imide, acetaldoxime, acetone oxime, Blocking agents, such as oxime-based agents such as methyl ethyl ketoxime, and amine-based agents such as diphenylaniline, aniline, and ethyleneimine, are included.

Moreover, it is preferable to introduce a hydrophilic group into the block isocyanate-based crosslinking agent from the viewpoint of providing water dispersibility in aqueous solvents. Also, as the hydrophilic group, it is preferable to introduce an anionic group such as a carboxyl group or a sulfonic acid group, or a nonionic group such as an oxyalkyl group. These hydrophilic groups can be created by previously reacting polyisocyanate, which serves as the base of the block isocyanate, with a compound having reactive groups such as a hydrophilic group and a hydroxyl group.

The crosslinking agent is preferably contained in an amount of 5% by mass or more and 50% by mass or less in the solid content of the total resin and crosslinking agent contained in the composition for forming an application layer. More preferably, it is 10 mass% or more and 45 mass% or less. More preferably, it is 10 mass% or more and 30 mass% or less, and most preferably, it is 10 mass% or more and 20 mass% or less. If it is 5% by mass or more, the strength of the resin of the coating layer is maintained and adhesion at high temperature and high humidity is good, and if it is 50% by mass or less, the flexibility of the resin of the coating layer is maintained and adhesion is maintained at room temperature, high temperature and high humidity, and is preferable. do.

The application layer in the easily adhesive polyester film of the present invention is formed by curing a composition containing a polyester having a polycyclic aromatic skeleton and a crosslinking agent having at least one skeleton selected from aliphatic, alicyclic, and heterocyclic. desirable. The expression that this composition is cured is used as such because it is difficult to properly express the chemical composition after reaction curing with a crosslinking agent.

(additive)

In the coating layer of the present invention, known additives, such as surfactants, antioxidants, heat stabilizers, weathering stabilizers, ultraviolet absorbers, organic lubricants, etc., to the extent that they do not impair the effects of the present invention. Pigments, dyes, organic or inorganic particles, antistatic agents, nucleating agents, etc. may be added. However, it is preferable not to use substances that are undesirable in terms of the environment, etc.

In the present invention, it is also preferable to add particles to the coating layer in order to further improve the blocking resistance of the coating layer. In the present invention, particles contained in the application layer include, for example, titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, etc., or mixtures thereof, and further, other general particles. Inorganic particles, such as calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, calcium fluoride, used in combination with others, styrene-based, acrylic-based, melamine-based, benzoguanamine-based, silicon-based. and organic polymer-based particles such as these.

The average particle size of the inert particles in the coating layer (average particle size based on number determined by SEM; the same applies hereinafter) is preferably 0.04 to 2.0 μm, and more preferably 0.1 to 1.0 μm. If the average particle diameter of the inert particles is 0.04 ㎛ or more, the formation of irregularities on the film surface becomes easier, so the handling properties such as slipperiness and winding of the film are improved, and the processability during bonding is good. desirable. On the other hand, it is preferable that the average particle diameter of the inert particles is 2.0 μm or less because it is difficult for particles to fall off. The particle concentration in the application layer is preferably 1 to 20% by mass based on the resin content.

In the present invention, the thickness (d: nm) of the application layer is preferably expressed in the following formula (1).

30≤d≤200 … Equation (1)

If it is prepared within this range, it is preferable because it is easy to achieve both processability and adhesion.

More preferably, it is 50 nm or more and 150 nm or less, and even more preferably, it is 70 nm or more and 100 nm or less. It is preferable that the thickness of the application layer is 30 nm or more because the adhesion is good. It is preferable that the thickness of the application layer is 200 nm or less because it is difficult to cause blocking.

The thickness of the coating layer was determined by observing the cross section of the cut film using a transmission electron microscope (TEM), and measuring the thickness of the coating layer at 10 points at random. The average value was taken as the thickness of the coating layer.

The surface free energy (γ _s : mN/m) of the coating layer present on the surface of the easily adhesive polyester film of the present invention is preferably within the range of the following formula (2).

43≤γ _s≤49 … Equation (2)

If adjusted within this range, adhesion reliability can be ensured and the requirements of the present invention can be satisfied.

More preferably, it is 44 mN/m or more and 48 mN/m or less, and even more preferably, it is 45 mN/m or more and 47 mN/m or less. When it is 43 mN/m or more, the proportion of segregation components distributed on the surface of the coating layer is small, and the adhesion to the hard coat layer applied later is good. In particular, it is preferable because the temporal stability and reliability of the adhesion can be secured. Moreover, if it is 49 mN/m or less, the adhesion to the initial hard coat layer is maintained high and is preferable.

The present invention focuses on the ratio of segregation components (mainly crosslinking agent components) present inside the surface of the coating layer.

The segregation component referred to herein refers to a urea compound or urethane compound in which the crosslinking agent component present in the composition for forming an application layer is transformed by reaction with moisture in the air, etc., and these compounds become localized on the surface, forming a hard coat layer. It appears to be a factor that reduces adhesion.

When the coating layer present on the surface of the easily adhesive polyester film of the present invention is observed with X-ray photoelectron spectroscopy (ESCA), the ratio of the amount of nitrogen atoms to the total amount of all elements (nitrogen atom ratio: A _N : at%) ) is preferably within the range of the following formula (3).

3.0≤A _N≤9.5 ... Equation (3)

Adjustment within this range is preferable because adhesion reliability can be ensured.

More preferably, it is 5.0 at% or more and 9.3 at% or less, and even more preferably, it is 7.0 at% or more and 9.0 at% or less. Setting it to 3.0 at% or more is preferable because adhesion to the initial hard coat layer is good. When it is 9.5 at% or less, the adhesion with the hard coat layer is stable even over time and adhesion reliability can be maintained, so it is preferable.

In ESCA measurement, the surface of the coating layer of the easily adhesive polyester film of the present invention is etched in the depth direction, and a distribution curve of the nitrogen element based on the element distribution measurement at each depth position is drawn, as shown in FIG. Obtain the same spectrum (horizontal axis: etching time (seconds), vertical axis: nitrogen atom ratio (at%)).

In the obtained distribution curve, the time (t ₁ ) (seconds) at which the nitrogen atom ratio becomes the lower limit, and the time at _which the nitrogen atom ratio becomes the intermediate value (A _N Z) between the maximum value (A _N When (t ₂ ) (seconds) is set, it is preferably within the range of the following formula (4).

(t ₂ /t ₁ )×100≥40 … Equation (4)

_The meaning of time (t _{2 )} in A _{N Z} is the point between the maximum value (A _N , which means the broadening of the nitrogen atom ratio in the depth direction.

That is, the ratio of (t ₂ ) to the overall expansion (t ₁ ) in the depth direction indicates that the larger the value, the more gradual the change in the amount of segregation of the segregation component from the surface of the coating layer.

More preferably, it is 47 or more, and even more preferably, it is 55 or more. When it is 40 or more, the amount of uneven distribution of segregation components decreases, and from this effect, adhesion reliability can be maintained, which is preferable.

There is no particular limitation on the method for satisfying the above formulas (2), (3), and (4), but it can be suitably adjusted by controlling the type and ratio of the resin and crosslinking agent in the composition for forming the coating layer.

When all of these equations (1) to (4) are satisfied, transparency, blocking resistance, adhesion to the hard coat layer, etc. are excellent, and in particular, adhesion stability over time is high, resulting in high reliability as a film. An adhesive polyester film can be obtained.

The composition for forming an application layer may contain a surfactant for the purpose of improving leveling properties during application and defoaming the coating liquid. The surfactant may be cationic, anionic, or nonionic, but silicone-based, acetylene glycol-based, or fluorine-based surfactants are preferred. These surfactants are preferably contained in the composition for forming an application layer within a range that does not impair the effect of suppressing iris-like color or adhesion under fluorescent light.

As a coating method, both the so-called in-line coating method, which applies coating simultaneously when forming a polyester base film, and the so-called offline coating method, which applies it with a separate coater after forming the polyester base film, can be applied. However, in-line coating It is more desirable because the law is efficient.

As a coating method, any known method can be used 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 brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, curtain coating method. etc. can be mentioned. Coating is performed using these methods alone or in combination.

In the present invention, a method of providing an application layer on a polyester film includes applying a coating liquid containing a solvent, particles, and resin to the polyester film and drying it. Examples of the solvent include water or a mixture of water and an organic solvent. Preferably, from the viewpoint of environmental issues, water alone or a mixture of water and a water-soluble organic solvent is preferred.

For example, examples of water-soluble organic solvents include alcohols such as isopropyl alcohol and ethanol, ketones such as methyl ethyl ketone, ethers such as butyl cellosolve, amines such as triethanolamine, and N-methylpyrroli. Amide series such as money can be mentioned.

The solid content concentration of the coating liquid may depend on the type of binder resin, the type of solvent, etc., but is preferably 2% by mass or more, and more preferably 4% by mass or more. The solid content concentration of the coating liquid is preferably 35% by mass or less, more preferably 15% by mass or less.

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

(Manufacture of easily adhesive polyester film)

The polyester film which becomes the base material of the easily adhesive polyester film of this invention can be manufactured according to a general polyester film manufacturing method. For example, the non-oriented polyester formed by melting the polyester resin and extruding it into a sheet shape is stretched in the longitudinal direction using the speed difference of the roll at a temperature above the glass transition temperature, and then stretched in the transverse direction by a tenter. A method of stretching and heat treatment is included.

The polyester film in the present invention may be a uniaxially stretched film or a biaxially stretched film. However, when the biaxially stretched film is used as a protective film on the front of the liquid crystal panel, rainbow-like color unevenness is not visible even when observed from directly above the film surface. However, caution is required because rainbow-like color unevenness may be observed when observed from an oblique direction.

This phenomenon occurs when a biaxially stretched film is made of refractive index ellipsoids with different refractive indices in the running direction, width direction, and thickness direction, and retardation becomes zero depending on the direction of light transmission inside the film (the refractive index ellipsoid appears to be a perfect circle). ) This is because direction exists. Therefore, when the liquid crystal display screen is observed from a specific oblique direction, a point at which retardation becomes zero may occur, and rainbow-like color irregularities will occur in concentric circles centered on that point. If the angle from just above the film plane (normal direction) to the position where rainbow-like color unevenness is visible is θ, this angle θ increases as the birefringence in the film plane increases, making rainbow-like color unevenness less visible. Since the angle θ tends to be small in a biaxially stretched film, a uniaxially stretched film is preferable because rainbow-like color unevenness is less likely to be seen.

However, in a completely uniaxial (uniaxially symmetric) film, the mechanical strength in the direction perpendicular to the orientation direction is significantly reduced, so it is not preferable. The present invention preferably has biaxiality (two-axis symmetry) in a range that substantially does not generate rainbow-like color unevenness, or in a range that does not generate rainbow-like color unevenness in the viewing angle range required for a liquid crystal display screen. do.

(Laminated polyester film)

A functional layer such as a hard coat layer can be laminated on the application layer of the easily adhesive polyester film of the present invention, and it can be preferably used mainly for optical purposes as a laminated polyester film. On the application layer, a hard coat layer made of an electron beam or ultraviolet ray-curable acrylic resin or a siloxane-based thermosetting resin can be provided.

It is also a preferable form to provide various functional layers on the application layer of the easily adhesive polyester film of the present invention. The functional layer is a layer that has functionality such as an anti-glare layer, an anti-glare anti-reflection layer, an anti-reflection layer, a low-reflection layer, and an anti-static layer in addition to the hard coat layer described above for the purpose of preventing reflection, suppressing glare, suppressing rainbow stains, suppressing scratches, etc. says As the functional layer, various types known in the technical field can be used, and the type is not particularly limited. Hereinafter, each functional layer will be described.

For example, to form the hard coat layer, known hard coat layer materials can be used, and are not particularly limited, but are polymerized by drying, heat, chemical reaction, or irradiation with any of electron beam, radiation, and ultraviolet rays, and/or Reactive resin compounds can be used. Such curable resins include melamine-based, acrylic-based, silicone-based, and polyvinyl alcohol-based curable resins. However, photocurable acrylic-based curable resins are preferred in terms of obtaining high surface hardness or optical design. As such an acrylic curable resin, polyfunctional (meth)acrylate monomers or acrylate oligomers can be used. Examples of acrylate oligomers include polyester acrylate, epoxy acrylate, and urethane acrylate. , polyether acrylate-based, polybutadiene acrylate-based, silicone acrylate-based, etc. By mixing a reactive diluent, a photopolymerization initiator, a sensitizer, etc. with these acrylic curable resins, a coating composition for forming the optical function layer can be obtained.

The hard coat layer may have an anti-glare function (anti-glare function) that scatters external light. The anti-glare function (anti-glare 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, it does not matter if it is 0.2% or more, and it does not matter if it is 0.5% or more.

In addition, in order to perform low-reflection processing (anti-reflection processing), which suppresses reflection of light by providing layers with different refractive indexes and changing the light transmission characteristics, the refractive index of the hard coat layer and the functional layer is adjusted, and ideally, It is preferable to realize a reflectance of 0 to 1.0%, more preferably 0 to 0.8%, and particularly preferably 0 to 0.5%. Of course, 0% is ideal, and it does not matter if it is 0.05% or more, and it does not matter if it is 0.1% or more.

In particular, the composition for the hard coat layer used in the present invention is a resin containing an aromatic component in a ratio of 5 mol% to 20 mol% relative to the total moles of monomers and oligomers constituting the resin in order to adjust the refractive index. It is common to use

The use of the easily adhesive polyester film of the present invention and the laminated polyester film obtained by laminating a functional layer on its application layer mainly covers all optical films, including prism lens sheets, AR (anti-reflection) films, and hard coat films. , base film, which is an optical member of LCD, flat TV, CRT, etc., such as diffusion plate and anti-shatter film; near-infrared absorption filter, which is a member of the front plate for plasma display; and transparent conductive material, such as touch panel and electroluminescence. It can be particularly suitable for use in films, etc.

Acrylic resins that are cured by electron beams or ultraviolet rays for forming the above-mentioned hard coat layer include, more specifically, those having acrylate-based or methacrylate-based functional groups, such as relatively low molecular weight polyester resins and polyester resins. For ether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiolpolyene resins, polyhydric alcohols, etc., oligomers or prepolymers such as (meth)acrylates of polyfunctional compounds and reactivity As a diluent, monofunctional monomers such as ethyl (meth)acrylate and ethylhexyl (meth)acrylate, and polyfunctional monomers such as trimethylolpropane tri(meth)acrylate, hexanediol (meth)acrylate, and tripropylene. Glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, Those containing neopentyl glycol di(meth)acrylate, etc. can be used.

In the case of electron beam or ultraviolet ray curable resin, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetramethylthiuram monosulfide, and thioxanthone are used as photopolymerization initiators among the above-mentioned resins. As a photosensitizer, a mixture of n-butylamine, triethylamine, tri-n-butylphosphine, etc. can be used.

Additionally, silicone-based (siloxane-based) thermosetting resin can be produced by hydrolyzing and condensing organosilane compounds alone or in combination of two or more types under an acid or base catalyst. In particular, in the case of low-reflection use, it is better to mix one or more fluorosilane compounds and perform hydrolysis and condensation reactions to improve low refractive index, stain resistance, etc.

(Manufacture of laminated polyester film)

Although the manufacturing method of the laminated polyester film using the easily adhesive polyester film in this invention is demonstrated, it is not limited to the demonstrated specific example.

The above-mentioned electron beam or ultraviolet ray curable acrylic resin, oligomer, monomer or siloxane-based thermosetting resin is applied to the application layer surface of the easily adhesive polyester film. When the application layer is provided on both sides, it is applied to at least one application layer surface. There is no need to particularly dilute the coating liquid, but there is no particular problem even if it is diluted with an organic solvent depending on the needs of the coating liquid's viscosity, wettability, coating film thickness, etc. The coating layer forms a hard coat layer by applying the coating liquid to the above-mentioned film, drying it as necessary, and then curing the coating layer by irradiating and heating with electron beams or ultraviolet rays according to the curing conditions of the coating liquid. do.

In the present invention, the thickness of the hard coat layer is preferably 1 to 15 μm. It is preferable that the thickness of the hard coat layer is 1 μm or more because the effects of the hard coat layer on chemical resistance, scratch resistance, antifouling properties, etc. are efficiently exhibited. On the other hand, if the thickness is 15 μm or less, the flexibility of the hard coat layer is maintained and there is no risk of cracks or the like, so it is preferable.

In terms of scratch resistance, it is desirable that the scratches are not visible to the naked eye when the coated surface is abraded with black paper. If no scratches are noticeable in the above evaluation, it is difficult for scratches to appear when passing the guide roll, which is preferable from the viewpoint of handling properties and the like.

Since the easily adhesive polyester film and laminated polyester film of the present invention are mainly used for optical purposes, it is preferable that they have high transparency. The lower limit of haze is ideally 0%, and the closer it is to 0%, the more preferable it is. The upper limit of the haze is preferably 2%, and if it is 2% or less, the light transmittance is good and a clear image can be obtained in a liquid crystal display device, so it is preferable. The haze of the polyester film can be measured, for example, by the method described later.

On the easily adhesive coating layer of the easily adhesive polyester film, a coating liquid for forming a hard coat layer of the above composition is applied as appropriate using a wire bar or the like, and dried at, for example, 70°C for 1 minute. Thus, the solvent can be removed. Next, the film to which the hard coat layer has been applied can be irradiated with ultraviolet rays of, for example, 300 mJ/cm2 using a high-pressure mercury lamp, thereby obtaining a laminated polyester film having a hard coat layer.

The adhesion between the easily adhesive coating layer and the hard coat layer is obtained by evaluation using the measurement method described later. Regarding the adhesiveness X after film forming, it is preferable that it is 95% or more. More preferably, it is 98% or more, and even more preferably, it is 100%. If it is 95% or more, it can be said that the adhesion between the application layer and the hard coat layer is sufficiently maintained. In addition, in the present invention, “after film forming” refers to continued storage in a temperature environment of 40°C or lower, and refers to within 6 months from film forming.

The adhesion Y under 80°C and 95%RH high temperature and high humidity conditions between the easily adhesive coating layer and the hard coat layer, evaluated according to the method described later, is the same as above, and the adhesion is preferably 95% or more. More preferably, it is 98% or more, and even more preferably, it is 100%. If it is 95% or more, the adhesion between the easily adhesive coating layer and the hard coat layer is generally satisfied under high temperature and high humidity conditions, and the passability in the post-processing step is generally satisfied.

Originally, it would be desirable to evaluate the adhesion after the easily adhesive polyester film was left in a room temperature environment where it is usually left for several weeks to several months. However, since it is difficult to measure the easily adhesive polyester film, this method uses accelerated measurement as a substitute measure. Typically, the evaluation is performed by leaving the product in a high temperature and high humidity environment of 80℃ and 90%RH for 24 hours.

The easily adhesive polyester film of the present invention is a film with high adhesion reliability, and its effect is that it has high adhesion even after exposure to a high-temperature, high-humidity environment. For this reason, the above-mentioned X(%) and Y(%) satisfy the following equation (5).

X-Y(%)≤5... Equation (5)

It is preferable that the value of equation (5) is 5% or less. More preferably, it is 2% or less, and even more preferably, it is 0%. If it is 5% or less, the difference between the adhesion after film forming and the adhesion after wet heat treatment is small, and it can be said that there is sufficient adhesion after film forming and after wet heat treatment. This is thought to be related to the characteristic that the adhesion to the hard coat layer does not decrease even if stored for a long time.

The easily adhesive polyester film of the present invention can be used for various purposes, but is preferably used in the manufacturing process of a polarizing plate used in a liquid crystal display device, and is particularly preferably used as a protective film for a polarizer constituting a polarizing plate. . Usually, polarizers are often made of polyvinyl alcohol, and the easily adhesive polyester film of the present invention is bonded to the polarizer using polyvinyl alcohol or an adhesive to which a crosslinking agent or the like is added as necessary. In that case, it is more preferable to use the application layer of the easily adhesive polyester film of the present invention not toward the surface on the side to which the polarizer is adhered, but toward the opposite side. The surface to be adhered to the polarizer of the easily adhesive polyester film of the present invention contains, for example, a polyester resin, a polyvinyl alcohol resin, and a crosslinking agent as described in International Publication No. 2012/105607. It is preferable that the adhesive layer is laminated.

Example

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

(1) Average particle size

[Measurement method using a scanning electron microscope]

The average particle diameter of the above particles can be measured by the following method. Photograph the particles with a scanning electron microscope (SEM) and measure the maximum diameter (distance between the two furthest points) of 300 to 500 particles at the same magnification that the size of the smallest particle is 2 to 5 mm. So, the average value is taken as the average particle diameter. The average particle diameter of particles present in the coating layer in the present invention can be measured by the measurement method.

[Dynamic light scattering method]

The average particle diameter of particles can also be determined by a dynamic light scattering method when producing particles or films. The sol was diluted with a dispersion medium, measured with a submicron particle analyzer N4 PLUS (manufactured by Beckman Coulter) using the parameters of the dispersion medium, and calculated by the cumulant method to obtain the average particle diameter. In the dynamic light scattering method, the average particle diameter of the particles in the sol is observed, and when there is aggregation of particles, the average particle diameter 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, the powder pulverized in a mortar was immersed in solvent 1 (which has a lower refractive index than the particles) and then added in small amounts to solvent 2 (which had a higher refractive index than the particles) until the fine particles were almost completely dissolved. It was added until it became transparent. The refractive index of this solution was measured using Abbe's refractometer (Abbe's refractometer manufactured by Atago Co., Ltd.). The measurement was conducted at 23°C with D line (wavelength 589 nm). The solvent 1 and solvent 2 are selected to be miscible with each other, and according to the refractive index, for example, 1,1,1,3,3,3-hexafluoro-2-propanol, 2-propanol, chloroform, carbon tetrachloride, toluene and solvents such as glycerin.

(3) Haze of easily adhesive polyester film for optical use

The haze of the easily adhesive polyester film was measured using a turbidimeter (NDH2000, manufactured by Nippon Denshoku) in accordance with JIS K 7136:2000.

(4) Adhesion (Adhesion X after film forming)

A hard coat layer was formed on the easily adhesive coating layer of the polyester film obtained in the example. The adhesion between the hard coat layer and the base film was determined based on the description of 8.5.1 of JIS-K5400-1990 for the polyester film for easy adhesion on which the hard coat layer was formed.

The coating liquid used to form the hard coat layer was prepared as follows.

(Preparation of coating liquid L for hard coat layer formation)

Methyl ethyl ketone 64.40 mass%

Dipentaerythritol hexaacrylate 27.20 mass%

(A-DPH manufactured by Shinnakamura Chemical)

Polyethylene glycol diacrylate 3.40 mass%

(Light acrylate 9EG-A manufactured by Kyoeisha Kagaku)

Bisphenol A diacrylate 4.00 mass%

(Light acrylate BP-4PA manufactured by Kyoeisha Kagaku)

Photopolymerization initiator 1.00 mass%

(Omnirad184 manufactured by IGM Resins B.V.)

The aromatic component in the total resin in the prepared hard coat coating liquid L was 13.3% in molar ratio.

(Formation of hard coat layer)

The easily adhesive polyester film prepared in the examples described later was stored at 20°C and a temperature and humidity of 65% RH, and 12 hours after film formation, the above composition was applied to the easily adhesive coating layer to form a hard coat layer. The solution was applied using a #14 wire bar, dried at 70°C for 1 minute, and the solvent was removed. Next, the film to which the hard coat layer was applied was irradiated with ultraviolet rays of 300 mJ/cm2 using a high-pressure mercury lamp, and a hard coat film having a hard coat layer with a thickness of 7 μm was obtained.

The specific measurement method of adhesion is as follows. Using a cutter guide with a gap of 2 mm, 100 checkerboard-shaped cuts are made on the hard coat layer surface, penetrating the hard coat layer and reaching the base film. Next, a cellophane adhesive tape (manufactured by Nichiban, No. 405; 24 mm wide) is applied to the surface of the checkerboard eye-shaped cut, and rubbed with an eraser to ensure complete adhesion. After that, the cellophane adhesive tape is vertically peeled off from the hard coat layer surface of the easily adhesive polyester film forming the hard coat layer, and the checkerboard pattern peeled off from the hard coat layer surface of the easily adhesive polyester film forming the hard coat layer. The number is counted with the naked eye, and the adhesion between the hard coat layer and the base film is determined from the formula below. Additionally, partially peeled checkerboard eyes are counted as peeled checkerboard eyes.

Adhesion (%) = {1-(Number of peeled checkerboard eyes/100)}×100

(5) Moist and heat resistance (adhesion after leaving at 80℃, 90%RH: Adhesion Y after moist heat treatment)

The obtained easily adhesive polyester film was left to stand in a high-temperature, high-humidity tank in an environment of 80°C and 90%RH for 24 hours, and then left to stand at room temperature (20°C, 65%RH) for 12 hours. After that, a hard coat layer was formed in the same manner as above, and adhesion was determined.

(6) Hard coat adhesion Z of an easily adhesive polyester film roll after being left for 6 months

A film roll of an easily adhesive polyester film was left in an environment of temperature: 0°C to 30°C and humidity: 10%RH to 80%RH for 6 months, a sample was taken from the film roll after the leave, and this was carried out in the same manner as above. A hard coat layer was formed on the adhesive coating layer, and adhesion was evaluated.

As for the adhesion reliability based on this adhesion Z, 99% or more was ◎, 95% or more but less than 99% was ○, and 95% or more was ○, and less than 95% was ×. Adhesion reliability ◎ and ○ with an adhesion Z of 95% or more are considered acceptable.

(7) Number average molecular weight

0.03 g of the resin was dissolved in 10 ml of tetrahydrofuran, using a GPC-LALLS 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) at a flow rate of 1 ml/min.

(8) Cross-sectional observation using a transmission electron microscope

The obtained easily adhesive polyester film was cut into 1 mm x 10 mm and embedded in epoxy resin, and then a cross-sectional thin section parallel to the short side of the embedded sample piece was produced using an ultramicrotome. Next, the sectioned thin film was stained with ruthenium tetroxide, and the portion that was not significantly damaged was observed using a transmission electron microscope (JEM2100, manufactured by Nippon Electronics) at an acceleration voltage of 200 kV and 20,000 times. From the observed image of the application layer, the thickness of the application layer was measured at 10 points at each level, and the average value was taken as the thickness of the application layer.

(9) Surface free energy

Water (drop volume: 1.8 μL) was measured on the coated layer surface of the easily adhesive polyester film obtained using a contact angle meter (fully automatic contact angle meter DM-701, manufactured by Kyowa Gaimen Chemical Co., Ltd.) under the conditions of 25°C and 50%RH. ), a droplet of diiodomethane (droplet volume 0.9 μL) was produced, and the contact angle was measured. The contact angle was adopted as the contact angle 10 seconds after each liquid was dropped onto the easily adhesive polyester film. The contact angle data of water and diiodomethane obtained by the above method are calculated using the "Kitazaki-Hata" theory to obtain the dispersion component γ _{sd and} the hydrogen bond component γ _sh of the surface free energy of the easily adhesive polyester film, The sum of each component was taken as surface free energy γ _s . This calculation was performed using the calculation software within the contact angle measurement software (FAMAS).

(10) Evaluation of nitrogen atom ratio on the surface of the applied layer

The ratio of the amount of nitrogen atoms to the total amount of all elements in the surface area (nitrogen atom ratio (A _N : at%)) was evaluated by X-ray photoelectron spectroscopy (ESCA) (K-Alpha ⁺ manufactured by Thermo Fisher Scientific). . Measurement conditions are shown below. Additionally, during analysis, background removal was performed using the Shirley method. In addition, A _N was calculated as the average value of the measurement results at three locations.

Measuring conditions

Excitation X-ray: Monochromated Al Kα ray

X-ray output: 12kV, 6mA

Photoelectron escape angle: 90°

Spot size: 400㎛ϕ

Pass energy: 50eV

Step: 0.1eV

(11) Measurement of nitrogen element distribution in the depth direction

Measurement of element distribution in the depth direction of the applied layer was performed by X-ray photoelectron spectroscopy (ESCA) (K-Alpha ⁺ manufactured by Thermo Fisher Scientific). Ar clusters, which can be expected to cause low damage to organic materials, were used as the ion source for etching. Additionally, the sample was rotated during etching to ensure uniform etching. In order to minimize the damage caused by X-ray irradiation, spectrum collection at each etching time was performed in snapshot mode, which allows evaluation in a short period of time. In addition, for the sake of evaluation, spectrum collection was performed every 30 seconds until the etching time was 120 seconds, then every 60 seconds until 720 seconds, and then every 120 seconds until 1200 seconds. Details of the measurement conditions are shown below. Additionally, during analysis, background removal was performed using the Shirley method.

Measuring conditions

Excitation X-ray: monochromated Al Kα ray

X-ray output: 12kV, 2.5mA

Photoelectron escape angle: 90°

Spot size: 200㎛ϕ

Pass energy: 150eV (Snapshot mode)

Acceleration voltage of ion gun: 6kV

Cluster size: small

Etching rate: 15㎚/min (polystyrene equivalent) ^※

Sample rotation during etching: Yes

For the calculation of the etching rate, monodisperse polystyrene with a molecular weight (Mn: 91000; Mw/Mn = 1.05) was dissolved in toluene and then produced on a silicon wafer by spin coating with a film thickness of 155 nm.

Based on the data evaluated in this way, a nitrogen distribution curve was drawn with the etching time from the surface of the coating layer on the horizontal axis and the ratio of the amount of nitrogen atoms to the total amount of all elements (nitrogen atom ratio) on the vertical axis. An example of a distribution curve is shown in Figure 1.

From the distribution curve shown in FIG. 1, the etching time (t ₁ ) (seconds) when no significant change is observed (at the lower limit) is read, and the maximum value (A _N By reading the etching time (t ₂ ) when the median value (A _N Z: at%) of A _N Y: at%) is reached and taking the ratio according to the above-mentioned equation (4), the segregation component can be determined. It was used as a measure to express discretion.

Here, the reading of t ₁ was determined as follows.

When plots of three points are taken in order from the left end of the horizontal axis in Figure 1, and the etching times are set to t _1-1 (seconds), t _1-2 (seconds), and t _1-3 (seconds) in that order from the left, The nitrogen atom ratio value at the etching time (t _1-1 ) is set to n ₁ (at%), and the nitrogen atom ratio value at the next etching time (t _1-2 ) (after 30 seconds, 60 seconds, or 120 seconds) is n ₂ (at%), and when the nitrogen atom ratio value at the next (30 seconds, 60 seconds, or 120 seconds later) etching time (t _1-3 ) is set to n ₃ (at%), these three points ( When taking the average value of (n ₁ , n ₂ , n ₃ ) and the difference between n ₁ , check whether the following relational expression (6) is satisfied, and continue to select three consecutive points in order until satisfied ( The following three points (t _1-1 (seconds) correspond to the above t _1-2 (seconds)), and t _1-1 (seconds) when relational expression (6) is first satisfied is the etching time t ₁ It was set to (seconds).

|n ₁ -(n ₁ + n ₂ + n ₃ )/3)|≤0.010(at%) … Equation (6)

The lower limit value (A _N Y) was set as the nitrogen atom ratio value at t ₁ (second).

From this lower limit, A _N Z is obtained by the following equation (7),

A _N Z ₌ (A _N Equation (7)

The etching time at that time was set to _t2 (seconds).

(Polymerization of copolyester resin (A) for application layer)

In a stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser, 342.0 parts by mass of dimethyl 2,6-naphthalenedicarboxylate, 35.0 parts by mass of dimethyl terephthalate, 35.5 parts by mass of dimethyl-5-sodium sulfoisophthalate, 198.6 parts by mass of ethylene glycol, 118.2 parts by mass of 1,6-hexanediol, and 0.4 parts by mass of tetra-n-butyl titanate were added, and a transesterification reaction was performed at a temperature of 160°C to 220°C for 4 hours. Additionally, 60.7 parts by mass of sebacic acid was added to perform an esterification reaction. Next, the temperature was raised to 255°C, the pressure of the reaction system was gradually reduced, and then the reaction was carried out for 1 hour and 30 minutes under a reduced pressure of 30 Pa to obtain a copolyester resin (A). The obtained copolyester resin (A) was light yellow and transparent. The reduced viscosity of the copolyester resin (A) was measured and found to be 0.72 dl/g. The glass transition temperature by DSC was 40°C, and the number average molecular weight was 20,000.

(Polymerization of copolyester resin (B) for application layer)

In a stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser, 293.0 parts by mass of dimethyl 2,6-naphthalenedicarboxylate, 128.0 parts by mass of dimethyl terephthalate, 41.6 parts by mass of dimethyl-5-sodium sulfoisophthalate, 125.0 parts by mass of ethylene glycol, 105.0 parts by mass of diethylene glycol, 142.0 parts by mass of 1,6-hexanediol, and 0.4 parts by mass of tetra-n-butyl titanate were added, and transesterification was carried out at a temperature of 160°C to 220°C for 4 hours. The reaction was carried out. Next, the temperature was raised to 255°C, the pressure of the reaction system was gradually reduced, and then the reaction was carried out for 1 hour and 30 minutes under reduced pressure of 30 Pa to obtain copolyester resin (B). The obtained copolyester resin (B) was light yellow and transparent. The reduced viscosity of the copolyester resin (B) was measured and found to be 0.69 dl/g. The glass transition temperature by DSC was 30°C, and the number average molecular weight was 21000.

(Polymerization of copolyester resin (C) for application layer)

In a stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser, 145.6 parts by mass of dimethyl terephthalate, 14.8 parts by mass of dimethyl-5-sodium sulfoisophthalate, 43.3 parts by mass of dimethyl azelaic acid, and 80.7 parts by mass of ethylene glycol. , 131.6 parts by mass of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, 70.9 parts by mass of 3-methyl-1,5-pentanediol, and 0.4 parts by mass of tetra-n-butyl titanate. and a transesterification reaction was performed over 4 hours at a temperature of 160°C to 220°C. Next, the temperature was raised to 255°C, the pressure of the reaction system was gradually reduced, and then the reaction was carried out for 1 hour and 30 minutes under reduced pressure of 30 Pa to obtain copolyester resin (C). The obtained copolyester resin (C) was light yellow and transparent. The reduced viscosity of the copolyester resin (C) was measured and found to be 0.65 dl/g. The glass transition temperature by DTSC was 40°C and the number average molecular weight was 19000.

(Polymerization of copolyester resin (D) for application layer)

194.2 parts by mass of dimethyl terephthalate, 184.5 parts by mass of dimethyl isophthalate, 14.8 parts by mass of dimethyl-5-sodium sulfoisophthalate, 233.5 parts by mass of diethylene glycol, 136.6 parts by mass of ethylene glycol, and 0.2 parts by mass of tetra-n-butyl titanate. Copolymerization polyester resin (D) was obtained in the same manner as the polymerization of resin (A) except for the addition. The reduced viscosity of the obtained copolyester resin (D) was measured and found to be 0.70 dl/g. The glass transition temperature by DSC was 40°C.

(Preparation of polyester water dispersion (Aw), (Bw), (Cw), (Dw))

30 parts by mass of copolyester resin (A) and 15 parts by mass of ethylene glycol-n-butyl ether were placed in a reactor equipped with a stirrer, thermometer, and reflux device, and heated and stirred at 110°C to dissolve the resin. After the resin was completely dissolved, 55 parts by mass of water was gradually added to the polyester solution while stirring. After addition, the liquid was cooled to room temperature while stirring to produce a milky white polyester resin (A) aqueous dispersion Aw (resin A solution) with a solid content of 25.0 mass%.

In the same manner, polyester resin (B) aqueous dispersion Bw (resin B solution) in which copolyester resin (B) was dissolved was produced.

In the same manner, a polyester resin (C) aqueous dispersion Cw (resin C solution) obtained by dissolving the copolyester resin (C) was produced.

In the same manner, a polyester resin (D) aqueous dispersion Dw (resin D solution) obtained by dissolving the copolyester resin (D) was produced.

(Preparation of polyurethane water dispersion (E))

[Polymerization of water-dispersible polyurethane resin containing aliphatic polycarbonate polyol as a component]

In a four-necked flask equipped with a stirrer, Dimroth condenser, nitrogen introduction tube, silica gel drying tube, and thermometer, 43.75 parts by mass of 4,4-diphenylmethane diisocyanate, 12.85 parts by mass of dimethylol butanoic acid, number average. 153.41 parts by mass of polyhexamethylene carbonate diol with a molecular weight of 2000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were added, and stirred at 75° C. for 3 hours in a nitrogen atmosphere, so that the reaction solution had a predetermined amine equivalent weight. It was confirmed that . Next, after cooling this reaction liquid to 40°C, 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 water-dispersed while stirring and mixing at 2000 min ^-1 . After that, a water-soluble polyurethane resin solution (resin E solution) with a solid content of 37% by mass was prepared by removing a part of acetone and water under reduced pressure. The glass transition temperature of the obtained polyurethane resin was -30°C.

(Synthesis of crosslinker P)

In a flask equipped with a stirrer, thermometer, and reflux condenser, 100 parts by mass of a polyisocyanate compound (NCO concentration 23.1%) having an isocyanurate structure prepared from 1,6-hexamethylene diisocyanate by a conventional method (NCO concentration 23.1%), N -35.00 parts by mass of 3,5-dimethylpyrazole was added dropwise to 17.5 parts by mass of methylpyrrolidone, and maintained at 70°C for 1 hour in a nitrogen atmosphere. After that, 12.50 parts by mass of dimethylol propionic acid was added dropwise. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate group had disappeared, 8.72 parts by mass of N,N-dimethylethanolamine was added. After stirring for 1 hour, an appropriate amount of water was added to obtain a block isocyanate-based aqueous dispersion (crosslinking agent P solution) with a solid content of 40% by mass.

(Synthesis of crosslinker Q)

In a flask equipped with a stirrer, thermometer, and reflux condenser, 100 parts by mass of a polyisocyanate compound (NCO concentration 23.3%) having an isocyanurate structure prepared from cyclohexane diisocyanate by a conventional method, and N-methylpyrrolidone. 35.00 parts by mass of 3,5-dimethylpyrazole was added dropwise to 17.5 parts by mass, and the mixture was maintained at 70°C for 1 hour in a nitrogen atmosphere.

After that, 12.50 parts by mass of dimethylol propionic acid was added dropwise. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate group had disappeared, 8.72 parts by mass of N,N-dimethylethanolamine was added. After stirring as is for 1 hour, an appropriate amount of water was added to obtain a blocked isocyanate-based aqueous dispersion (crosslinking agent Q solution) with a solid content of 40% by mass.

(Synthesis of crosslinker R)

In a flask equipped with a stirrer, thermometer, and reflux condenser, 100 parts by mass of a polyisocyanate compound (NCO concentration 23.1%) having an isocyanurate structure prepared from 2,5-diisocyanatothiophene by a conventional method (NCO concentration 23.1%), N -35.00 parts by mass of 3,5-dimethylpyrazole was added dropwise to 17.5 parts by mass of methylpyrrolidone, and maintained at 70°C for 1 hour in a nitrogen atmosphere.

After that, 12.50 parts by mass of dimethylol propionic acid was added dropwise. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate group had disappeared, 8.72 parts by mass of N,N-dimethylethanolamine was added. After stirring for 1 hour, an appropriate amount of water was added to obtain a block isocyanate-based aqueous dispersion (cross-linking agent R solution) with a solid content of 40% by mass.

(Synthesis of crosslinker S)

In a flask equipped with a stirrer, thermometer, and reflux condenser, 168 parts by mass of hexamethylene diisocyanate and 220 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 400) were added, stirred at 120°C for 1 hour, and added at 4,4' - 26 parts by mass of dicyclohexylmethane diisocyanate and 3.8 parts by mass of 3-methyl-1-phenyl-2-phosphorene-1-oxide (2% by mass based on the total isocyanate) as a carbodimidization catalyst were added, The mixture was stirred for an additional 5 hours at 185°C under a nitrogen stream. By measuring the infrared spectrum of the reaction solution, it was confirmed that the absorption of the isocyanate group was lost. After cooling to 60°C, 567 parts by mass of ion-exchanged water was added to obtain a carbodiimide-based crosslinking agent (crosslinking agent S solution) with a solid content of 40% by mass.

(Synthesis of crosslinker T)

In a flask equipped with a stirrer, thermometer, and reflux condenser, 100 parts by mass of a polyisocyanate compound (NCO concentration 22.3%) having an isocyanurate structure prepared from 2,4-tolylene diisocyanate by a conventional method (NCO concentration 22.3%), N- 35.00 parts by mass of 3,5-dimethylpyrazole was added dropwise to 17.5 parts by mass of methylpyrrolidone, and the mixture was maintained at 70°C for 1 hour in a nitrogen atmosphere.

After that, 12.50 parts by mass of dimethylol propionic acid was added dropwise. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate group had disappeared, 8.72 parts by mass of N,N-dimethylethanolamine was added. After stirring as is for 1 hour, an appropriate amount of water was added to obtain a block isocyanate-based aqueous dispersion (cross-linking agent T solution) with a solid content of 40% by mass.

(zirconia particles)

In a 3 liter glass container, 2283.6 g of pure water and 403.4 g of oxalic acid dihydrate were added and heated to 40°C to prepare a 10.72% by 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 slowly added and mixed for 30 minutes, then stirred at 90°C for 30 minutes. Heating was performed. Next, 1747.2 g of 25.0% by 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 this hydrothermal treatment was completely reduced to a sol with no unpungidated matter. The obtained sol contained 4.0% by mass of ZrO ₂ , had a pH of 6.8, and an average particle diameter determined by the dynamic light scattering method of 19 nm. Additionally, the transmittance measured by adjusting the sol with pure water to a ZrO ₂ concentration of 2.0 mass% was 88%. When the particles were observed using a transmission electron microscope, most of them were aggregated ZrO _primary particles of around 7 nm. 4000 g of zirconia sol with a ZrO ₂ concentration of 4.0 mass% obtained by performing the hydrothermal treatment described above was washed and concentrated while gradually adding pure water using an ultrafiltration device to obtain a ZrO ₂ concentration of 13.1 mass%, pH 4.9, and ZrO ₂ concentration of 13.1 mass%. 953 g of zirconia sol with a transmittance of 76% was obtained. The refractive index of the obtained zirconia-based fine particles was 1.75.

(zirconia sol)

3.93 g of a 20 mass% citric acid aqueous solution and 11.0 g of a 25 mass% tetramethylammonium hydroxide aqueous solution were added to 300 g of zirconia sol with a ZrO ₂ concentration of 13.1 mass% obtained by performing the above washing and concentration, and then further concentrated using an ultrafiltration device. As a result, 129 g of high-concentration zirconia sol with 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 according to a dynamic light scattering method. Additionally, this zirconia sol had no sediment and was stable for more than one month under conditions of 50°C.

(titania particles)

12.09 kg of titanium tetrachloride aqueous solution containing 7.75% by mass of titanium tetrachloride (manufactured by Osaka Titanium Technologies Co., Ltd.) based on TiO ₂ conversion, and 4.69 kg of ammonia water containing 15% by mass of ammonia (manufactured by Ubekosan Co., Ltd.) were mixed. , a white slurry liquid of pH 9.5 was prepared. Next, this slurry was filtered and washed with pure water to obtain 9.87 kg of a water-containing titanic acid cake with a solid content of 10% by mass. Next, 11.28 kg of hydrogen peroxide water (manufactured by Mitsubishi Gas Chemical Co., Ltd.) containing 35% by mass of hydrogen peroxide and 20.00 kg of pure water were added to this cake, and then heated at a temperature of 80°C for 1 hour with stirring. Additionally, 57.52 kg of pure water was added to obtain 98.67 kg of an aqueous titanic peroxide solution containing 1% by mass of titanic acid peroxide based on TiO ₂ conversion. This aqueous solution of titanic acid peroxide was transparent, yellow-brown, and had a pH of 8.5.

Next, 4.70 kg of cation exchange resin (manufactured by Mitsubishi Chemical Co., Ltd.) was mixed with 98.67 kg of the aqueous titanic acid peroxide solution, and potassium tartrate (manufactured by Showa Kako Co., Ltd.) was added at 1% by mass based on SnO ₂ conversion. 12.33 kg of an aqueous solution of potassium tartrate was slowly added while stirring. Next, the cation exchange resin into which potassium ions and the like were introduced was separated, placed in an autoclave (120L, manufactured by Daiatsu Glass Kogyo Co., Ltd.), and heated at a temperature of 165°C for 18 hours.

(Titania Sol)

Next, the obtained mixed aqueous solution was cooled to room temperature, and then concentrated with an ultrafiltration membrane device (ACV-3010, manufactured by Asahi Kasei Co., Ltd.) to obtain titanium-based fine particles (hereinafter referred to as “P-1”) with a solid content of 10% by mass. 9.90 kg of water-dispersed sol containing . The solids contained in the sol thus obtained were measured by the above-mentioned method and found to be titanium-based fine particles (primary particles) composed of a composite oxide containing titanium and tin and having a rutile-type crystal structure. Additionally, the content of metal components contained in these titanium-based fine particles was measured and found to be 87.2 mass% of TiO ₂ , 11.0 mass% of SnO ₂ , and 1.8 mass% of K ₂ O based on the oxide conversion of each metal component. Additionally, the pH of the mixed aqueous solution was 10.0. In addition, the water-dispersed sol containing the titanium-based fine particles is transparent and milky white, and the average particle diameter of the titanium-based fine particles contained in this water-dispersed sol is 35 nm, and coarse particles having a particle diameter of 100 nm or more The distribution frequency was 0%. Additionally, the refractive index of the obtained titanium-based fine particles was 2.42.

(Zirconia/titania mixed sol)

A zirconia/titania mixed sol with a solid content concentration of 13% by mass was produced by mixing the zirconia particles and titania particles obtained above in respective ratios.

(Example 1)

(Preparation of coating solution)

A coating liquid with the following composition was prepared.

36.47 parts by mass of water

37.42 parts by mass of isopropyl alcohol

1.21 parts by mass of silica sol

(Silica sol with average particle diameter of 40 nm, solid content concentration of 40 mass%)

1.11 parts by mass of silica sol

(Silica sol with average particle diameter of 450 nm, solid content concentration of 4 mass%)

Resin A solution 20.06 parts by mass

(Solid content concentration 25% by mass)

3.14 parts by mass of crosslinker P solution

(Solid content concentration 40% by mass)

Surfactant 0.25 parts by mass

(Fluorine-based, solid content concentration 10% by mass)

High boiling point solvent 0.34 parts by mass

(Manufacture of easily adhesive polyester film)

As a film raw material polymer, PET resin pellets with an intrinsic viscosity (solvent: phenol/tetrachloroethane = 60/40) of 0.62 dl/g and substantially free of particles were heated to 6 °C at 135°C under reduced pressure of 133 Pa. Time was dry. After that, it was supplied to an extruder, melt-extruded into a sheet form at about 280°C, and rapidly cooled and tightly solidified on a rotary cooling metal roll maintained at a surface temperature of 20°C to obtain an unstretched PET sheet.

This unstretched PET sheet was heated to 100°C with a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction with a roll group with a difference in peripheral speed, to obtain a uniaxially stretched PET film.

Next, the above coating liquid was applied to one side of the PET film by roll coating, then dried at 80°C, and the coating amount after final stretching and drying was adjusted to be 0.12 g/m2. Subsequently, the film was stretched 4.0 times in the width direction at 150°C using a tenter, heated at 230°C while fixing the length of the film in the width direction, and further relaxed in the width direction at 230°C to form a film with a thickness of 38 μm. A film roll of the easily adhesive polyester film was wound.

The thickness of the easily adhesive coating layer of the obtained easily adhesive polyester film was 80 nm, and the surface free energy was 46.3 mN/m.

Next, the nitrogen atom ratio on the surface by ESCA was 8.6 at%, and the distribution curve of the nitrogen atom ratio in the depth direction by surface etching was as shown in FIG. 2. t ₁ and t ₂ obtained from these results are t ₁ = 111 (seconds) and t ₂ = 65 (seconds), respectively, and the value obtained from equation (4) is (t ₂ /t ₁ ) × 100 = 59 ( seconds).

Next, on the easily adhesive coating layer of the easily adhesive polyester film, a laminated polyester film was obtained according to the above-mentioned formation method using the above-mentioned coating liquid L for hard coat layer formation.

When the adhesion of the hard coat layer of the obtained laminated polyester film was evaluated, the adhesion X was 100%.

Furthermore, the obtained easily adhesive polyester film was left to stand in a high temperature, high humidity tank in an environment of 80°C and 90%RH for 24 hours, and then left to stand at room temperature for 12 hours. After that, a hard coat layer was formed on the easily adhesive coating layer of the easily adhesive polyester film after treatment using the coating liquid L for hard coat layer formation, and a laminated polyester film was obtained.

When the adhesion of the hard coat layer of the obtained laminated polyester film was evaluated, the adhesion Y was 100%.

From this result, in equation (5), X-Y = 0 (%). These results are listed in Table 1.

The film roll of the easily adhesive polyester film was left in an environment of temperature: 0°C to 30°C and humidity: 10%RH to 80%RH for 6 months, samples were taken from the film roll after the leave, and the same as above. A hard coat layer was formed on the easily adhesive coating layer, the adhesiveness Z was evaluated, and it is listed in Table 1.

As a result of the evaluation, the adhesion Z was 100%, and the adhesion reliability was ◎, which was desirable in terms of adhesion reliability.

(Examples 2 to 3)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that the thickness of the applied resin layer was adjusted as shown in Table 1. The results are as shown in Table 1.

(Example 4)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that a coating liquid of the following composition was prepared.

35.62 parts by mass of water

37.42 parts by mass of isopropyl alcohol

1.21 parts by mass of silica sol

(Silica sol with average particle diameter of 40 nm, solid content concentration of 40 mass%)

1.11 parts by mass of silica sol

(Silica sol with average particle diameter of 450 nm, solid content concentration of 4 mass%)

Resin A solution 22.32 parts by mass

(Solid content concentration 25% by mass)

1.72 parts by mass of crosslinker P solution

(Solid content concentration 40% by mass)

Surfactant 0.25 parts by mass

(Fluorine-based, solid content concentration 10% by mass)

High boiling point solvent 0.34 parts by mass

Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Example 5)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that a coating liquid of the following composition was prepared.

37.41 parts by mass of water

37.42 parts by mass of isopropyl alcohol

1.21 parts by mass of silica sol

(Silica sol with average particle diameter of 40 nm, solid content concentration of 40 mass%)

1.11 parts by mass of silica sol

(Silica sol with average particle diameter of 450 nm, solid content concentration of 4 mass%)

Resin A solution 17.56 parts by mass

(Solid content concentration 25% by mass)

4.70 parts by mass of crosslinker P solution

(Solid content concentration 40% by mass)

Surfactant 0.25 parts by mass

(Fluorine-based, solid content concentration 10% by mass)

High boiling point solvent 0.34 parts by mass

Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Example 6)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that the coating liquid was prepared using the crosslinking agent Q solution. Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Example 7)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that the coating liquid was prepared using the crosslinking agent R solution. Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Example 8)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that the coating liquid was prepared using the crosslinking agent S solution. Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Example 9)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that the coating liquid was prepared using the resin B solution. Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Example 10)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that the coating liquid was prepared using the Resin C solution. Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Example 11)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that a coating liquid of the following composition was prepared.

36.47 parts by mass of water

37.42 parts by mass of isopropyl alcohol

Zirconia sol 1.21 parts by mass

1.11 parts by mass of silica sol

(Silica sol with average particle diameter of 450 nm, solid content concentration of 4 mass%)

Resin A solution 20.06 parts by mass

(Solid content concentration 25% by mass)

3.14 parts by mass of crosslinker P solution

(Solid content concentration 40% by mass)

Surfactant 0.25 parts by mass

(Fluorine-based, solid content concentration 10% by mass)

High boiling point solvent 0.34 parts by mass

Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Example 12)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that a coating liquid of the following composition was prepared.

36.47 parts by mass of water

37.42 parts by mass of isopropyl alcohol

Titania sol 1.21 parts by mass

1.11 parts by mass of silica sol

(Silica sol with average particle diameter of 450 nm, solid content concentration of 4 mass%)

Resin A solution 20.06 parts by mass

(Solid content concentration 25% by mass)

3.14 parts by mass of crosslinker P solution

(Solid content concentration 40% by mass)

Surfactant 0.25 parts by mass

(Fluorine-based, solid content concentration 10% by mass)

High boiling point solvent 0.34 parts by mass

Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Example 13)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that a coating liquid of the following composition was prepared.

36.47 parts by mass of water

37.42 parts by mass of isopropyl alcohol

1.21 parts by mass of zirconia/titania mixed sol

(Zirconia mass 75% by mass, solid content concentration 13% by mass relative to the total mass of zirconia/titania)

1.11 parts by mass of silica sol

(Silica sol with average particle diameter of 450 nm, solid content concentration of 4 mass%)

Resin A solution 20.06 parts by mass

(Solid content concentration 25% by mass)

3.14 parts by mass of crosslinker P solution

(Solid content concentration 40% by mass)

Surfactant 0.25 parts by mass

(Fluorine-based, solid content concentration 10% by mass)

High boiling point solvent 0.34 parts by mass

Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Comparative Examples 1 to 2)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that the thickness of the applied resin layer was adjusted as shown in Table 1. The results are as shown in Table 1.

(Comparative Example 3)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that a coating liquid of the following composition was prepared.

38.63 parts by mass of water

37.42 parts by mass of isopropyl alcohol

1.21 parts by mass of silica sol

(Silica sol with average particle diameter of 40 nm, solid content concentration of 40 mass%)

1.11 parts by mass of silica sol

(Silica sol with average particle diameter of 450 nm, solid content concentration of 4 mass%)

Resin A solution 14.30 parts by mass

(Solid content concentration 25% by mass)

Crosslinker P solution 6.74 parts by mass

(Solid content concentration 40% by mass)

Surfactant 0.25 parts by mass

(Fluorine-based, solid content concentration 10% by mass)

High boiling point solvent 0.34 parts by mass

Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Comparative Example 4)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that a coating liquid of the following composition was prepared.

35.06 parts by mass of water

37.42 parts by mass of isopropyl alcohol

1.21 parts by mass of silica sol

(Silica sol with average particle diameter of 40 nm, solid content concentration of 40 mass%)

1.11 parts by mass of silica sol

(Silica sol with average particle diameter of 450 nm, solid content concentration of 4 mass%)

Resin A solution 23.83 parts by mass

(Solid content concentration 25% by mass)

Crosslinker P solution 0.78 parts by mass

(Solid content concentration 40% by mass)

Surfactant 0.25 parts by mass

(Fluorine-based, solid content concentration 10% by mass)

High boiling point solvent 0.34 parts by mass

Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Comparative Example 5)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that the coating liquid was prepared using the resin D solution. Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Comparative Example 6)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that a coating liquid of the following composition was prepared.

36.80 parts by mass of water

37.29 parts by mass of isopropyl alcohol

1.33 parts by mass of silica sol

(Silica sol with average particle diameter of 40 nm, solid content concentration of 40 mass%)

1.23 parts by mass of silica sol

(Silica sol with average particle diameter of 450 nm, solid content concentration of 4 mass%)

Resin A solution 13.31 parts by mass

(Solid content concentration 25% by mass)

Resin E solution 5.99 parts by mass

(Solid content concentration 37% by mass)

3.47 parts by mass of crosslinker P solution

(Solid content concentration 40% by mass)

Surfactant 0.25 parts by mass

(Fluorine-based, solid content concentration 10% by mass)

High boiling point solvent 0.34 parts by mass

Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

(Comparative Example 7)

An easily adhesive polyester film was obtained in the same manner as in Example 1, except that the coating liquid was prepared using the crosslinking agent T solution. Evaluation of the obtained easily adhesive polyester film was performed in the same manner as in Example 1, and the results were as shown in Table 1.

According to the present invention, an easily adhesive polyester film that ensures adhesion reliability after being left in a high-temperature, high-humidity environment for a long time can be provided, and application to optical applications becomes easier.

A _N
A _N Y: Lower limit of nitrogen atom ratio (at%)
A _N Z: Median value (at%) of the nitrogen atom ratio corresponding to the middle of A _N X and A _N Y
t ₁ : Etching time (seconds) when the nitrogen atom ratio reaches the lower limit
t ₂ : Etching time (seconds) corresponding to A _N Z
t _1-1 , t _1-2 , t _1-3 : Etching time (seconds) for three consecutive points

Claims (4)

Easily adhesive ( As a polyester film,
The thickness (d: nm) of the application layer satisfies the following equation (1),
The surface free energy (γ _s : mN/m) of the surface of the coating layer that is not in contact with the polyester film of the coating layer satisfies the following equation (2),
According to X-ray photoelectron spectroscopy (ESCA), the nitrogen atom ratio (A _N : at%) on the surface of the coating layer satisfies the following equation (3),
In the distribution curve of _the nitrogen element based on element distribution measurement in the depth direction, the maximum value of the nitrogen atom _ratio (A _N : at%) and the time t ₂ (seconds) at which the median value of A _N Y (A _N Z: at %) (t ₂ /t ₁ ) satisfies the following equation (4). Polyester film:
30≤d≤200 … Equation (1)
43≤γ _s≤49 … Equation (2)
3.0≤A _N≤9.5 ... Equation (3)
(t ₂ /t ₁ )×100≥40 … Equation (4). According to claim 1,
The adhesion
An easily adhesive polyester in which the above-mentioned adhesion film:
XY(%)≤5... Equation (5). The method of claim 1 or 2,
An easily adhesive polyester film wherein the polyester having a polycyclic aromatic skeleton is a polyester having a naphthalene skeleton. The method according to any one of claims 1 to 3,
An easily adhesive polyester film wherein the crosslinking agent having at least one skeleton selected from aliphatic, alicyclic, and heterocyclic is an isocyanate crosslinking agent having at least one skeleton selected from aliphatic, alicyclic, and heterocyclic.