WO2012108449A1 - Highly adhesive polyester film - Google Patents

Abstract

Provided is an highly adhesive polyester film that has an excellent appearance and adhesiveness. The highly adhesive polyester film has a coating layer on at least one surface thereof. The main components of the coating layer are a urethane resin and a blocked isocyanate, the dissociation temperature of the blocked isocyanate is 130°C or lower, and the boiling point of a blocking agent is 180°C or higher.

Description

Easy-adhesive polyester film

The present invention relates to an easily adhesive polyester film excellent in adhesion and appearance. Specifically, the present invention relates to an easily-adhesive polyester film suitable as a base material for optical functional films such as a hard coat film, an antireflection film, a light diffusion sheet, a lens sheet, a near-infrared shielding film, a transparent conductive film, and an antiglare film.

In general, the base material of an optical functional film used as a member of various displays such as a liquid crystal display is a transparent heat composed of polyethylene terephthalate (PET), acrylic, polycarbonate (PC), triacetyl cellulose (TAC), polyolefin, or the like. A plastic resin film is used.

When using the thermoplastic resin film as a base material for various optical functional films, functional layers corresponding to various applications are laminated. For example, in a liquid crystal display, a protective film (hard coat layer) that prevents scratches on the surface, an antireflection layer (AR layer) that prevents reflection of external light, a prism layer used for light collection and diffusion, brightness A functional layer such as an improved light diffusion layer may be mentioned. Among such substrates, particularly polyester films are widely used as substrates for various optical functional films because they are excellent in transparency, dimensional stability and chemical resistance and are relatively inexpensive.

Generally, since the biaxially oriented polyester film surface is highly crystallized, it has a drawback of poor adhesion to various paints, adhesives and inks. For this reason, methods for imparting easy adhesion to the biaxially oriented polyester film surface by various methods have been proposed.

For example, a method for imparting easy adhesion to a base film by providing a coating layer containing various resins such as polyester, acrylic, polyurethane, and acrylic graft polyester on the surface of the base polyester film is known. (Patent Documents 1 to 4). Among these coating methods, the polyester film before the completion of crystal orientation is coated on the base film with an aqueous coating solution containing the resin solution or a dispersion in which the resin is dispersed in a dispersion medium, and after drying, Stretch at least uniaxially, then heat treatment to complete the orientation of the polyester film (so-called in-line coating method), after the production of the polyester film, after applying a water-based or solvent-based coating liquid to the film, A drying method (so-called off-line coating method) is industrially implemented.

Patent Documents 5 and 6 also disclose an easily adhesive polyester film obtained by adding a resin and an isocyanate cross-linking agent to a coating solution from the viewpoint of improving adhesiveness.

JP 2000-141574 A Japanese Patent No. 3900191 JP 2007-253512 A JP 2009-220376 A Japanese Patent No. 4130964 JP 2009-178955 A

In recent years, with the development of portable information terminals such as tablet PCs and smartphones, higher definition, lighter weight, and high designability of displays are required. For example, a member such as an icon sheet that is conventionally made of a glass material has been replaced with a film. Such a member may be subjected to a mirror-like metallic gloss treatment by metal vapor deposition or the like on a part of the edge surface from the viewpoint of design. However, in such an embodiment, even when the film itself has no visual problem at all, fine irregularities on the coated surface may be observed when a design such as a mirror finish is applied.

Furthermore, it is expected to extend the service life of conventional home appliances with displays to reduce the global environmental load. Therefore, it was considered that the optical functional film used as a member also needs to maintain adhesiveness for a long time even under high temperature and high humidity. However, although the easy-adhesion film as disclosed in the above patent document shows good adhesion at the beginning, a decrease in adhesion strength is inevitable in long-term use under high temperature and high humidity, and the initial performance is There was a problem of not maintaining for a long time.

Also, along with the refinement of optical design, various resin composition types having different refractive indexes and strengths are being used as the photo-curing resin constituting the optical functional layer. Therefore, a highly versatile and easy-adhesive film that exhibits the same degree of adhesion to various photocurable resins is desirable.

In view of the above problems, the present invention provides an easy-adhesive polyester film having excellent adhesion and appearance, and more preferably having good adhesion to various optical resin compositions.

As a result of intensive studies to solve the above problems, the inventor surprisingly has a urethane resin and a blocked isocyanate as main components, the dissociation temperature of the blocked isocyanate is 130 ° C. or less, and the boiling point of the blocking agent is It has been found that adhesion and appearance are improved by using a coating layer having a temperature of 180 ° C. or higher, and the present invention has been achieved.

That is, the said subject can be achieved by the following solution means.
(1) A polyester film having a coating layer on at least one surface, wherein the coating layer is mainly composed of urethane resin and blocked isocyanate, the dissociation temperature of the blocked isocyanate is 130 ° C. or less, and the boiling point of the blocking agent is 180. An easily adhesive polyester film having a temperature of ℃ or higher.
(2) The easily adhesive polyester film according to claim 1, wherein the urethane resin is a urethane resin containing an aliphatic polycarbonate polyol as a constituent component.
(3) Ratio of absorbance (A ₁₄₆₀ ) near 1460 cm ⁻¹ derived from the aliphatic polycarbonate component and absorbance (A ₁₅₃₀ ) near 1530 cm ⁻¹ derived from the urethane component in the infrared spectrum of the coating layer (A ₁₄₆₀ / A ₁₅₃₀ ) is an easily adhesive polyester film having a value of 0.40 to 1.55.
(4) The easily adhesive polyester film, wherein a mass ratio of urethane resin to blocked isocyanate (urethane resin / block isocyanate) in the coating layer is 1/9 to 9/1.
(5) The said easily-adhesive polyester film whose haze of a polyester film is 2.0% or less.
(6) At least one optical functional layer selected from a hard coat layer, a light diffusion layer, a lens layer, an electromagnetic wave absorption layer, a near infrared ray blocking layer, and a transparent conductive layer is provided on the coating layer of the easily adhesive polyester film. A laminated polyester film for optics that is laminated.
(7) An easy-adhesive polyester film roll obtained by winding the easy-adhesive polyester film.

The easily adhesive polyester film of the present invention is excellent in adhesion and appearance, and more preferably has good adhesion to various optical resin compositions. Therefore, the easily adhesive polyester film of the present invention is suitable as a base film for optical members such as displays.

(Polyester film)
The polyester resin constituting the substrate in the present invention includes polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, and copolymerization components such as diols such as diethylene glycol, neopentyl glycol, and polyalkylene glycol. A polyester resin or the like obtained by copolymerizing a component or a dicarboxylic acid component such as adipic acid, sebacic acid, orthophthalic acid, isophthalic acid, or 2,6-naphthalenedicarboxylic acid can be used.

The polyester resin suitably used in the present invention mainly contains at least one of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate as a constituent component. Among these polyester resins, polyethylene terephthalate is most preferable from the balance between physical properties and cost. Moreover, these polyester films can improve chemical resistance, heat resistance, mechanical strength, etc. by biaxially stretching.

The biaxially stretched polyester film may be a single layer or a multilayer. Moreover, as long as it exists in the range with the effect of this invention, each of these layers can contain various additives in a polyester resin as needed. Examples of the additive include an antioxidant, a light resistance agent, an antigelling agent, an organic wetting agent, an antistatic agent, an ultraviolet absorber, and a surfactant.

In addition, in order to improve handling characteristics such as film slipperiness, rollability and blocking resistance, and wear characteristics such as wear resistance and scratch resistance, inert particles may be included in the polyester film. However, since the film of the present invention is used as a base film for an optical member, it is required to have excellent handling properties while maintaining high transparency. Specifically, when used as a substrate film for an optical member, the total light transmittance of the easily adhesive polyester film is preferably 85% or more, more preferably 87% or more, and even more preferably 88% or more. 89% or more is more preferable, and 90% or more is particularly preferable.

For high definition, it is preferable that the content of inert particles in the base film is as small as possible. Therefore, it is a preferred embodiment that a multilayer structure in which particles are contained only in the surface layer of the film is used, or that the particles are substantially not contained in the film and fine particles are contained only in the coating layer.

In particular, from the viewpoint of transparency, when an inert particle is practically not contained in the polyester film, an inorganic and / or heat-resistant polymer particle is contained in the aqueous coating solution in order to improve the handling property of the film. It is also preferable to form irregularities on the surface of the coating layer.

Note that “substantially no inert particles” means, for example, in the case of inorganic particles, when the element derived from the particles is quantitatively analyzed by fluorescent X-ray analysis, 50 ppm or less, preferably 10 ppm or less, Preferably, the content is below the detection limit. This means that even if particles are not actively added to the base film, contaminants derived from foreign substances and raw material resin or dirt adhering to the line or equipment in the film manufacturing process will be peeled off and mixed into the film. It is because there is a case to do.

(Coating layer)
It is important that the easy-adhesive polyester film of the present invention has a coating layer mainly composed of a urethane resin and a blocked isocyanate having a dissociation temperature of 130 ° C. or lower and a blocking agent having a boiling point of 180 ° C. or higher. Here, the “main component” means that it is contained in an amount of 50% by mass or more, more preferably 70% by mass or more as the total solid component contained in the coating layer.

As in the above patent document, a flexible urethane resin is suitably used to impart easy adhesion, but from the point of improving the adhesion of the coating layer, a cross-linked structure is positively introduced to the hard coating layer. It was considered desirable to do. Therefore, as in Patent Documents 5 and 6, examples using isocyanate as a crosslinking agent have been proposed. However, since these cross-linking agents are highly reactive, they tend to react with water in an aqueous coating solution to lose the cross-linking reactivity or to react with a urethane resin to easily generate aggregates. Therefore, the so-called pot life is short, and it has been difficult to stably apply for a long time. Then, like patent document 2, the isocyanate which blocked the functional group with the blocking agent dissociated by heat addition may be used. However, due to the influence of the undissociated block agent, sufficient adhesion may not be obtained when high adhesion such as adhesion (moisture heat resistance) is required under high temperature and high humidity.

Furthermore, when intensive study was made on the minute unevenness of the coated surface visually recognized when the mirror surface treatment or the like was performed, it was surprisingly found that such a minute coated surface unevenness was caused by the above blocked isocyanate. . This was thought to be because minute uneven pinholes were formed on the coated surface when the dissociated blocking agent volatilized at a high temperature.

Therefore, as a result of intensive studies, the inventor is excellent in adopting a coating layer mainly composed of a urethane resin and a blocked isocyanate having a dissociation temperature of 130 ° C. or lower and a blocking agent having a boiling point of 180 ° C. or higher. It was found that good adhesion and appearance can be obtained. That is, when the dissociation temperature exceeds the above temperature, it is considered that the dissociation of the blocking agent due to heat addition is insufficient, and a sufficient cross-linked structure cannot be obtained, resulting in a decrease in adhesion, particularly moist heat resistance. Moreover, when the boiling point of a blocking agent is less than the said temperature, it is thought that the blocking agent which remained in the application layer volatilizes by heat addition, and an application | coating external appearance falls.

The present invention can improve the adhesion (humidity and heat resistance) with a hard coat layer, a lens layer, and other optical functional layers under high temperature and high humidity according to the above embodiment. Further, the configuration of the present invention will be described in detail below.

(Urethane resin)
The urethane resin of the present invention includes at least a polyol component and a polyisocyanate component as constituent components, and further includes a chain extender as necessary. The urethane resin of the present invention is a polymer compound in which these constituent components are mainly copolymerized by urethane bonds.

Examples of the polyol component include polyvalent carboxylic acids (for example, malonic acid, succinic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or acid anhydrides thereof and polyhydric alcohols (for example, , Ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, neopentyl glycol, 1,6-hexane Polyester polyols obtained from the reaction of diol etc .; polyether polyols such as polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol ; Polycarbonates polyols; polyolefin polyols; like acrylic polyols. Especially, it is preferable to contain the aliphatic polycarbonate polyol which is excellent in heat resistance and hydrolysis resistance in the polyol component which is a structural component of the urethane resin of this invention. In the optical use of the present invention, it is preferable to use an aliphatic polycarbonate polyol from the viewpoint of preventing yellowing.

When an aliphatic polycarbonate component is included as a component of the urethane resin, it is derived from an aliphatic polycarbonate component measured by infrared spectroscopy of the coating layer, in order to broaden the photocurable resin applicable as an optical functional layer The ratio (A ₁₄₆₀ / A ₁₅₃₀ ) of the absorbance in the vicinity of 1460 cm ⁻¹ (A ₁₄₆₀ ) to the absorbance in the vicinity of 1530 cm ⁻¹ derived from the urethane component (A ₁₅₃₀ ) is preferably 0.40 to 1.55.

When an optical functional layer is laminated on a base film, strong stress is generated between the optical functional layer and the coating layer due to shrinkage during curing of the photocurable resin constituting the optical functional layer and swelling during high-temperature and high-humidity treatment. . When such a laminated film is placed under high temperature and high humidity, deterioration of the coating layer proceeds due to dissolution or swelling or hydrolysis by a solvent contained in the photocurable resin. As a result, it was considered that the above-mentioned stress could not be endured, the optical functional layer was peeled off, and the adhesiveness was lowered. Therefore, in order to maintain a high degree of adhesion under high temperature and high humidity, as has been conventionally considered, not only is the coating layer strongly crosslinked or hydrolysis resistance is imparted, but also the above stress. It would be desirable to have the flexibility to withstand. However, simply having flexibility is problematic in terms of solvent resistance and strength. Therefore, it is most desirable to make these conflicting characteristics compatible. Therefore, by adopting a configuration having the above infrared spectral characteristics as a urethane resin, it is possible to suitably achieve both flexibility and durability. Thereby, since the stress due to the shrinkage at the time of curing of the photocurable resin and the swelling due to the swelling at the time of high temperature and high humidity treatment can be relieved, it is possible to obtain good adhesion with various photocurable resins and the like. We believe that even under high-temperature and high-humidity environments, it is possible to prevent deterioration of the coating layer, such as dissolution, swelling, and hydrolysis due to the solvent and diluent monomer remaining in the coating layer.

Here, the absorbance around 1460 cm ⁻¹ (A ₁₄₆₀ ) is derived from the bending vibration unique to the CH bond of the methylene group contained in the aliphatic polycarbonate component. Therefore, the magnitude of the absorbance (A ₁₄₆₀ ) near 1460 cm ⁻¹ depends on the amount of the aliphatic polycarbonate polyol component constituting the urethane resin present in the coating layer. On the other hand, the absorbance (A ₁₅₃₀ ) in the vicinity of 1530 cm ⁻¹ is derived from the bending vibration specific to the N—H bond contained in the urethane component. Therefore, the magnitude of the absorbance (A ₁₅₃₀ ) near 1530 cm ⁻¹ depends on the amount of urethane components (the number of urethane bonds) constituting the urethane resin present in the coating layer. When an isocyanate-based crosslinking agent is used as the crosslinking agent, the absorbance (A ₁₅₃₀ ) in the vicinity of 1530 cm ⁻¹ is the amount of urethane component (number of urethane bonds) as the sum of the amount of urethane resin present in the coating layer and the amount of crosslinking agent. Depends on. Therefore, these absorbance ratios (A ₁₄₆₀ / A ₁₅₃₀ ) indicate that both components having different characteristics coexist in a specific ratio. In the present invention, the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) is 0.40 to 1.55, but the lower limit of the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) is preferably 0.45, more preferably 0.8. 50. The upper limit of the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) is preferably 1.50, more preferably 1.40, still more preferably 1.30, and still more preferably 1.20. When the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) is less than 0.40, the amount of the hard urethane component is excessive, and the stress relaxation of the coating layer is lowered, so that the heat and moisture resistance may be lowered. Further, when the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) exceeds 1.55, the aliphatic component of the flexible aliphatic polycarbonate is excessively increased, and the solvent resistance of the coating layer is lowered, so that the heat and moisture resistance is lowered. There is a case.

Examples of the aliphatic polycarbonate polyol include aliphatic polycarbonate diols and aliphatic polycarbonate triols, and aliphatic polycarbonate diols can be preferably used. Examples of the aliphatic polycarbonate diol that is a component of the urethane resin of the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl. Diols such as -1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol Examples include aliphatic polycarbonate diols obtained by reacting one or more of these with carbonates such as dimethyl carbonate, diphenyl carbonate, ethylene carbonate, and phosgene. The number average molecular weight of the aliphatic polycarbonate diol is preferably 1500 to 4000, more preferably 2000 to 3000. When the number average molecular weight of the aliphatic polycarbonate diol is small, the ratio of the aliphatic polycarbonate component constituting the urethane resin is relatively small. Therefore, in order to make the ratio (A ₁₄₆₀ / A ₁₅₃₀ ) within the above range, it is preferable to control the number average molecular weight of the aliphatic polycarbonate diol within the above range. If the number average molecular weight of the aliphatic polycarbonate diol is large, the absorbance (A ₁₄₆₀ ) around 1460 cm ⁻¹ derived from the aliphatic polycarbonate component increases and the aliphatic component increases, so that the solvent resistance decreases. , The adhesion may be reduced. When the number average molecular weight of the aliphatic polycarbonate diol is small, a strong urethane component increases, and stress due to shrinkage and swelling of the photocurable resin cannot be relieved, and adhesion may be lowered.

Examples of the polyisocyanate that is a constituent component of the urethane resin of the present invention include aromatic aliphatic diisocyanates such as xylylene diisocyanate; isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane. Aliphatic diisocyanates such as hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, or other polyisocyanates obtained by adding trimethylolpropane or the like to one or more of these compounds. Kind. When an aromatic diisocyanate is used, there is a problem of yellowing, which may not be preferable for optical use requiring high transparency. Moreover, since it becomes a hard coating film compared with aliphatic diisocyanate, the stress by shrinkage | contraction and swelling of photocurable resin etc. cannot be relieved, and adhesiveness may fall.

The ratio (A ₁₄₆₀ / A ₁₅₃₀ ) can also be adjusted by a chain extender. Examples of the chain extender that can be used in the present invention include divalent glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol; glycerin, trimethylolpropane, penta Trihydric or higher polyhydric alcohols such as erythritol; diamines such as ethylenediamine, hexamethylenediamine and piperazine; amino alcohols such as monoethanolamine and diethanolamine; thiodiglycols such as thiodiethylene glycol; It is done. However, when a chain extender having a short main chain is used, the absorbance (A ₁₅₃₀ ) in the vicinity of 1530 cm ⁻¹ derived from the urethane component increases, and the flexibility of the coating layer may decrease. Therefore, a chain extender having a long main chain is preferable. From the viewpoint of imparting flexibility to the coating layer, a chain extender of diol or diamine having a length of 4 to 10 carbon atoms in the main chain is preferable. From these points, 1,4-butanediol, 1,6-hexanediol, hexamethylenediamine and the like are preferable as the chain extender used in the present invention.

The coating layer of the present invention is preferably provided by an in-line coating method described later using an aqueous coating solution. Therefore, it is desirable that the urethane resin of the present invention is water dispersible.

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

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

When a polyol compound having a carboxylic acid (salt) group is used as a copolymerization component in order to impart water dispersibility, the composition molar ratio of the polyol compound having a carboxylic acid (salt) group in the urethane resin is the urethane resin. When the total polyisocyanate component is 100 mol%, it is preferably 3 to 60 mol%, more preferably 5 to 40 mol%. If the composition molar ratio is less than 3 mol%, water dispersion may be difficult. Moreover, when the said composition molar ratio exceeds 60 mol%, since water resistance falls, moist heat resistance may fall.

The glass transition temperature of the urethane resin of the present invention is preferably less than 30 ° C, more preferably less than 0 ° C. When the glass transition temperature is less than 30 ° C., it is easy to achieve suitable flexibility from the viewpoint of stress relaxation of the coating layer.

The urethane resin is preferably contained in an amount of 10% by mass to 90% by mass with respect to the crosslinking agent. In particular, when high adhesion is required as in a lens layer, the content is more preferably 20% by mass or more and 80% by mass or less. When the content of the urethane resin is large, the adhesiveness under high temperature and high humidity is lowered, and when the content is low, the initial adhesiveness is lowered.

In order to improve the solvent resistance of the urethane resin of the present invention, a self-crosslinking group may be introduced into the urethane resin itself in addition to the addition of a crosslinking agent. Thereby, the crosslinking degree of resin increases and solvent resistance improves. Although it does not specifically limit as a self-crosslinking group used for this invention, The comparatively stable silanol group can be used suitably also in aqueous | water-based coating liquid.

The urethane resin of the present invention may be contained in two or more types in order to improve adhesion.

A resin other than the urethane resin of the present invention may be contained in order to improve adhesiveness. For example, an acrylic resin, a polyester resin, etc. are mentioned.

(Block isocyanate)
In the present invention, it is necessary to contain a blocked isocyanate having a dissociation temperature of 130 ° C. or lower and a blocking agent having a boiling point of 180 ° C. or higher in the coating layer. The blocked isocyanate can be obtained by reacting a polyisocyanate and a block agent. The dissociation temperature and boiling point can be measured by differential thermal analysis.

The dissociation temperature of the blocked isocyanate is preferably 130 ° C. or lower, more preferably 125 ° C. or lower, and still more preferably 120 ° C. or lower. In the case of a drying step after application of the coating solution or an in-line coating method, the blocking agent is dissociated from the functional group by heat addition in the film forming step, and a regenerated isocyanate group is generated. Therefore, a crosslinking reaction with a urethane resin or the like proceeds, and the adhesiveness at normal temperature, high temperature and high humidity is improved. When the dissociation temperature of the blocked isocyanate is equal to or lower than the above temperature, the dissociation of the blocking agent proceeds sufficiently, so that the adhesiveness, particularly the moist heat resistance is improved. The lower limit of the dissociation temperature is not particularly limited as long as it is room temperature or higher for stabilization of the coating solution, but is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and further preferably 80 ° C. or higher.

A compound having one active hydrogen in the molecule is preferably used for the blocking agent. In this case, in order to make the dissociation temperature relatively low as described above, it is preferable to employ a compound capable of obtaining a high electron density. For example, a compound having a heterocyclic ring or a similar structure in the molecule is preferably used.

The boiling point of the blocking agent is preferably 180 ° C or higher, more preferably 190 ° C or higher, further preferably 200 ° C or higher, and further preferably 210 ° C or higher. The higher the boiling point of the blocking agent, the more the evaporation of the blocking agent is suppressed by the heat application in the film-forming process in the case of the drying process after application of the coating solution or the in-line coating method, and the appearance of the coating layer surface due to minute coating surface irregularities Defects are improved and appearance and transparency are improved. The upper limit of the boiling point of the blocking agent is not particularly limited, but it seems that the upper limit is about 300 ° C. from the viewpoint of productivity. Since the boiling point is related to the molecular weight, in order to increase the boiling point of the blocking agent, it is preferable to use a blocking agent having a large molecular weight. The molecular weight of the blocking agent is preferably 50 or more, more preferably 60 or more, and more preferably 80 or more. preferable.

The dissociation temperature used for the blocked isocyanate of the present invention is 130 ° C. or lower, and the blocking agent has a boiling point of 180 ° C. or higher.
Bisulfite compounds: Sodium bisulfite, etc.
Pyrazole compounds: 3,5-dimethylpyrazole, 3-methylpyrazole, 4-bromo-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, etc.
Active methylene series: Malonic acid diester (dimethyl malonate, diethyl malonate, di-n-butyl malonate, di (2-ethylhexyl) malonate, etc.
Triazole compounds: 1,2,4-triazole, etc.
Is mentioned. Of these, pyrazole compounds are preferred from the viewpoints of moisture and heat resistance and prevention of yellowing.

The polyisocyanate which is a precursor of the blocked isocyanate of the present invention is obtained by introducing diisocyanate. Examples thereof include urethane-modified products, allophanate-modified products, urea-modified products, biuret-modified products, uretdione-modified products, uretoimine-modified products, isocyanurate-modified products, and carbodiimide-modified products.

Diisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 1,5-naphthylene diene Isocyanate, 1,4-naphthylene diisocyanate, phenylene diisocyanate, tetramethylxylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4 '-Diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, 3,3'-dimethoxydiphenyl-4 Aromatic diisocyanates such as 4'-diisocyanate; Aromatic aliphatic diisocyanates such as xylylene diisocyanate; Alicyclic diisocyanates such as isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and 1,3-bis (isocyanatomethyl) cyclohexane And aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate. Aliphatic and alicyclic diisocyanates and modified products thereof are preferred from the viewpoint of transparency, adhesiveness, and heat and humidity resistance. When an aromatic diisocyanate is used, there is a problem of yellowing, which may not be preferable for optical use requiring high transparency. Moreover, since it becomes a hard coating film compared with aliphatic diisocyanate, the stress by shrinkage | contraction and swelling of photocurable resin etc. cannot be relieved, and adhesiveness may fall.

The blocked isocyanate of the present invention can introduce a hydrophilic group into the polyisocyanate which is a precursor in order to impart water solubility or water dispersibility. Hydrophilic groups include (1) quaternary ammonium salts of dialkylamino alcohols and quaternary ammonium salts of dialkylaminoalkylamines, (2) sulfonates, carboxylates, phosphates, etc. (3) alkoxy groups Examples thereof include polyethylene glycol and polypropylene glycol blocked at one end. When a hydrophilic site is introduced, it becomes (1) cationic, (2) anionic, and (3) nonionic. Among them, since other water-soluble or water-dispersible resins are often anionic, anionic and nonionic resins that can be easily compatible are preferred. In addition, anionic ones are excellent in compatibility with other resins, and nonionic ones do not have an ionic hydrophilic group, so that they are also preferable for improving heat and moisture resistance. In addition, anionic and cationic ones aggregate with other resins or self-aggregate, which may affect transparency and appearance, and among these, nonionic ones are more preferable.

As the anionic hydrophilic group, those having a hydroxyl group for introduction into polyisocyanate and a carboxylic acid group for imparting hydrophilicity are preferable. Examples include glycolic acid, lactic acid, tartaric acid, citric acid, oxybutyric acid, oxyvaleric acid, hydroxypivalic acid, dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutanoic acid, polycaprolactone having a carboxylic acid group, and the like. An organic amine compound is preferable for neutralizing the carboxylic acid group. For example, ammonia, methylamine, ethylamine, propylamine, isopropylamine, butylamine, 2-ethylhexylamine, cyclohexylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine Linear, branched, 1, 2 or tertiary amines having 1 to 20 carbon atoms such as ethylenediamine; cyclic amines such as morpholine, N-alkylmorpholine and pyridine; monoisopropanolamine, methylethanolamine, methylisopropanolamine; Dimethylethanolamine, diisopropanolamine, diethanolamine, triethanolamine, diethylethanolamine, triethanol A hydroxyl group-containing amines such as triethanolamine and the like.

The nonionic hydrophilic group is preferably 3 to 50, more preferably 5 to 30 repeating units of polyethylene glycol and polypropylene glycol with ethylene oxide and / or propylene oxide blocked at one end with an alkoxy group. When the repeating unit is small, the compatibility with the resin is deteriorated and the haze is increased. When the repeating unit is large, the adhesiveness under high temperature and high humidity may be decreased.

In the blocked isocyanate of the present invention, nonionic, anionic, cationic and amphoteric surfactants can be added to improve water dispersibility. For example, nonionic systems such as polyethylene glycol and polyhydric alcohol fatty acid esters; anionic systems such as fatty acid salts, alkyl sulfates, alkylbenzene sulfonates, sulfosuccinates, and alkyl phosphates; cationic systems such as alkylamine salts and alkylbetaines; Surfactants such as carboxylic acid amine salts, sulfonic acid amine salts, and sulfate ester salts are exemplified.

In addition to water, a water-soluble organic solvent can be contained. For example, the organic solvent used in the reaction or it can be removed and another organic solvent can be added.

The mass ratio of urethane resin to blocked isocyanate (urethane resin / block isocyanate) in the coating layer is preferably 1/9 to 9/1, more preferably 1/9 to 8/2, and more preferably 2/8 to 6/4. Further preferred. Moreover, as content rate of the blocked isocyanate in the solid component of an application layer, 10 mass% or more and 90 mass% or less are preferable. More preferably, it is 20 mass% or more and 80 mass% or less. When the amount is small, the solvent resistance of the coating layer decreases, and the adhesion under high temperature and high humidity decreases. In many cases, the flexibility of the resin of the coating layer decreases, and the adhesion at normal temperature, high temperature and high humidity decreases. Two or more types of blocked isocyanates may be combined, or two or more types of blocking agents may be combined. In that case, at least one blocked isocyanate must satisfy the provisions of the present invention.

In the present invention, two kinds of crosslinking agents may be mixed in order to improve the coating film strength. Examples of the crosslinking agent to be mixed include melamine, epoxy, carbodiimide, and oxazoline. A carbodiimide type and an oxazoline type are preferable from the viewpoint of the stability over time of the coating solution and the effect of improving the adhesion of the coating layer under high temperature and high humidity treatment. Moreover, in order to promote a crosslinking reaction, a catalyst etc. are used suitably as needed.

(Additive)
In the present invention, particles may be contained in the coating layer. Particles are (1) silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, zirconium dioxide, titanium dioxide, satin white, silicic acid Inorganic particles such as aluminum, diatomaceous earth, calcium silicate, aluminum hydroxide, hydrous halloysite, magnesium carbonate, magnesium hydroxide, (2) acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene / acrylic, Styrene / butadiene, polystyrene / acrylic, polystyrene / isoprene, polystyrene / isoprene, methyl methacrylate / butyl methacrylate, melamine, polycarbonate, urea, epoxy, urethane , Phenolic, diallyl phthalate, and organic particles such as polyester.

The average particle diameter of the particles is not particularly limited, but the average particle diameter is preferably 1 to 500 nm, and more preferably 1 to 100 nm from the viewpoint of maintaining the transparency of the film.

The particles may contain two or more kinds of particles having different average particle diameters.

In addition, said average particle diameter measures the major axis of the particle | grains of ten or more particles which exist in the cross section of a coating layer, image | photographs the cross section of a laminated film by 120,000 times magnification using a transmission electron microscope (TEM). , And can be obtained as their average value.

The particle content is preferably 0.5% by mass or more and 20% by mass or less. When the amount is small, sufficient blocking resistance cannot be obtained. Further, scratch resistance is deteriorated. When the amount is large, not only the transparency of the coating layer is deteriorated, but also the coating strength is lowered.

A surfactant may be included for the purpose of improving the leveling property of the coating layer and defoaming the coating solution. The surfactant may be any of cationic, anionic and nonionic, but is preferably a silicone, acetylene glycol or fluorine surfactant. These surfactants are preferably contained in a range that does not impair the adhesion to the optical functional layer, for example, 0.005 to 0.5% by mass in the coating solution.

The easily adhesive polyester film of the present invention preferably has a haze value of 2.0% or less, more preferably 1.8% or less, and even more preferably 1.5% or less. In order to obtain high transparency, it is preferable to reduce the average particle diameter of the urethane resin. Thereby, the dispersibility and compatibility of the resin are improved, and high transparency is obtained. From the viewpoint of transparency, the average particle size of the urethane resin used in the coating layer is preferably 150 nm or less, and more preferably 100 nm or less.

In order to impart other functionality to the coating layer, various additives may be included within a range that does not impair the adhesion with the optical functional layer. Examples of the additive include fluorescent dyes, fluorescent whitening agents, plasticizers, ultraviolet absorbers, pigment dispersants, foam suppressors, antifoaming agents, preservatives, and antistatic agents.

In the present invention, as a method of providing a coating layer on a polyester film, a method of coating and drying a coating solution containing a solvent, particles and a resin on the polyester film can be mentioned. Examples of the solvent include organic solvents such as toluene, water, and a mixed system of water and a water-soluble organic solvent. Preferably, water alone or a mixture of a water-soluble organic solvent and water is used from the viewpoint of environmental problems. preferable.

(Manufacture of easily adhesive polyester film)
The method for producing an easily adhesive polyester film of the present invention will be described by taking a polyethylene terephthalate (hereinafter abbreviated as PET) film as an example, but it is not limited to this.

The coating layer is formed by coating a coating solution on at least one surface of the PET film at any stage of the formed film or film manufacturing process. In particular, coating (in-line coating method) in a film production process capable of high heat addition for dissociation of the blocking agent is preferable. There is no particular problem even if the coating layer is formed on both sides of the PET film. The solid content concentration of the resin composition in the coating solution is preferably 2 to 35% by mass, and particularly preferably 4 to 15% by mass.

As a method for applying the coating solution to the PET film, any known method can be used. 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. It is done. These methods can be used alone or in combination.

In the case of the in-line coating method, the coating layer is formed by applying the coating solution to an unstretched or uniaxially stretched PET film, drying it, stretching at least uniaxially, and then performing a heat treatment.

In the present invention, the thickness of the finally obtained coating layer is preferably 20 to 350 nm, and the coating amount after drying is preferably 0.02 to 0.5 g / m ² . If the coating amount is less than 0.02 g / m ² , the effect on adhesiveness is almost lost. On the other hand, when the coating amount exceeds 0.5 g / m ² , haze increases.

The film serving as the substrate can be obtained as follows, taking a PET film as an example. After sufficiently drying the PET resin in a vacuum, it is supplied to an extruder, melted and extruded at about 280 ° C. from a T-die into a rotating cooling roll into a sheet, cooled and solidified by an electrostatic application method, and unstretched PET. Get a sheet. The unstretched PET sheet may have a single layer configuration or a multilayer configuration by a coextrusion method. Moreover, it is preferable not to contain an inert particle substantially in PET resin.

The obtained unstretched PET sheet is stretched 2.5 to 5.0 times in the longitudinal direction with a roll heated to 80 to 120 ° C. to obtain a uniaxially stretched PET film. Furthermore, the end of the film is gripped with a clip, led to a hot air zone in the tenter heated to 70 to 140 ° C., stretched 2.5 to 5.0 times in the width direction, and then into the heat treatment zone in the tenter. Guidance and heat treatment. In order that the blocking agent of the present invention is suitably dissociated by heat addition, the maximum temperature in the tenter and the heat treatment time during heat treatment are preferably 160 ° C. or higher and 1 second or longer, and 180 ° C. or higher and 5 seconds or longer. More preferred. In order to suitably suppress the volatilization of the blocking agent, the maximum temperature and the heat treatment temperature in the tenter during the heat treatment are preferably 250 ° C. or less and 60 seconds or less, and more preferably 240 ° C. or less and 50 seconds or less. In addition, the said heat processing time says the residence time from the heat processing zone in a tenter after extending | stretching to a cooling zone.

An easy-adhesive polyester film roll obtained by winding up the easy-adhesive polyester film of the present invention is also a preferred embodiment of the present invention. Since the coating layer of the present invention has good blocking resistance due to the addition of a crosslinking agent, a film roll having excellent unwinding properties can be obtained.

The thickness of the easy-adhesive polyester film of the present invention is not particularly limited, but can be arbitrarily determined in the range of 25 to 500 μm according to the specification of the intended use. The upper limit of the thickness of the easily adhesive polyester film is preferably 400 μm, particularly preferably 350 μm. On the other hand, the lower limit of the film thickness is preferably 50 μm, particularly preferably 75 μm. If the film thickness is less than 25 μm, the mechanical strength tends to be insufficient. On the other hand, when the film thickness exceeds 500 μm, it tends to be difficult to wind it into a roll.

When the easily adhesive polyester film of the present invention is used as a roll, the winding length and width are appropriately determined depending on the use of the film roll. The winding length of the film roll is preferably 1500 m or more, more preferably 1800 m or more. The upper limit of the winding length is preferably 5000 m. Moreover, it is preferable that the width | variety of a film roll is 500 mm or more, More preferably, it is 800 mm. In addition, as an upper limit of the width | variety of a film roll, 2000 mm is preferable.

(Laminated film for optics)
The laminated polyester film for optics of the present invention is selected from a hard coat layer, a light diffusing layer, a lens layer, an electromagnetic wave absorbing layer, a near-infrared blocking layer, and a transparent conductive layer on the surface of the above-mentioned polyester film coating layer, It is obtained by laminating one optical function layer. The shape of the lens layer is not particularly limited. For example, a prism-shaped lens, a Fresnel-shaped lens, a microlens, or the like can be suitably applied.

The material used for the optical functional layer is not particularly limited, and a resin compound that is polymerized and / or reacted by drying, heat, chemical reaction, or irradiation with an electron beam, radiation, or ultraviolet light is used. be able to. Examples of such curable resins include melamine-based, acrylic-based, silicone-based, and polyvinyl alcohol-based curable resins. However, in terms of obtaining high surface hardness or optical design, a photocurable acrylic curable resin is used. Resins are preferred. As such an acrylic curable resin, a polyfunctional (meth) acrylate monomer or an acrylate oligomer can be used. Examples of the acrylate oligomer include polyester acrylate, epoxy acrylate, urethane acrylate, Examples include ether acrylate, polybutadiene acrylate, and silicone acrylate. A coating composition for forming the optical functional layer can be obtained by mixing a reactive diluent, a photopolymerization initiator, a sensitizer and the like with these acrylic curable resins.

In addition, the polyester film of the present invention can provide good adhesive strength even for other than the above optical uses. Specifically, adhesion such as photographic photosensitive layer, diazo photosensitive layer, matte layer, magnetic layer, inkjet ink receiving layer, hard coat layer, UV curable resin, thermosetting resin, printing ink and UV ink, dry laminate and extrusion laminate Examples thereof include vacuum deposition, electron beam deposition, sputtering, ion plating, and CVD plasma polymerization of an agent, a metal, an inorganic substance, or an oxide thereof, and an organic barrier layer.

Next, the present invention will be described in detail using examples and comparative examples, but the present invention is not limited to the following examples. The evaluation method used in the present invention is as follows.

(1) Intrinsic viscosity Based on JIS K 7367-5, a mixed solvent of phenol (60% by mass) and 1,1,2,2-tetrachloroethane (40% by mass) was used as a solvent and measured at 30 ° C.

(2) Dissociation temperature and boiling point The dissociation temperature of the blocked isocyanate and the boiling point of the blocking agent were measured by thermogravimetric / differential thermal analysis (TG / DTA). The boiling point was measured under atmospheric pressure.

(3) Glass transition temperature Based on JIS K7121, the glass transition start temperature was calculated | required from the DSC curve using the differential scanning calorimeter (The Seiko Instruments Inc. make, DSC6200).

(4) Absorbance measurement by infrared spectroscopy About the obtained easily-adhesive polyester film, the coating layer was scraped off and about 1 mg of a sample was collected. A pressure was applied to the collected sample to prepare a coating layer sample piece (size: about 50 μm × about 50 μm) molded into a film having a thickness of about 1 μm. Further, a sample piece (blank sample piece) was prepared in the same manner as described above for a PET resin having the same quality as the base film as a blank sample.
The prepared sample piece was placed on a KBr plate, and an infrared absorption spectrum was measured by a microscopic transmission method under the following conditions. The infrared spectrum of the coating layer was determined as the difference spectrum between the infrared spectrum obtained from the coating layer sample piece and the spectrum of the blank sample piece.
Absorbance around 1460 cm ^-1 derived from an aliphatic polycarbonate component (A ₁₄₆₀₎ is 1460 and the value of the absorption peak height having an absorption maximum in the region of ± 10 cm ^-1, the absorbance in the vicinity of 1530 cm ^-1 derived from urethane component (A ₁₅₃₀ ) is the value of the absorption peak height having an absorption maximum in the region of 1530 ± 10 cm ⁻¹ . The baseline was a line connecting the hems on both sides of each maximum absorption peak. The absorbance ratio was determined from the obtained absorbance by the following formula.
(Absorbance ratio) = A ₁₄₆₀ / A ₁₅₃₀

(Measurement condition)
Apparatus: FT-IR analyzer SPECTRA TECH IRμs / SIRM
Detector: MCT
Resolution: 4cm ^-1
Integration count: 128 times

(5) Total light transmittance of easy-adhesive polyester film The total light transmittance of the obtained easily-adhesive polyester film was measured using a turbidimeter (Nippon Denshoku, NDH2000) according to JIS K 7105. .

(6) Haze of easy-adhesive polyester film The haze of the obtained easy-adhesive polyester film was measured using a turbidimeter (Nippon Denshoku, NDH2000) in accordance with JIS K7136.

(7) Adhesiveness A cutter guide having a gap distance of 2 mm is provided on the surface of the optically laminated polyester film, the photocurable hard coat layer, the photocurable acrylic layer, or the photocurable urethane / acrylic layer (hereinafter referred to as an optical functional layer). Used to make 100 grid-like cuts that penetrate the optical functional layer and reach the base film. Next, a cellophane adhesive tape (manufactured by Nichiban Co., Ltd., cello tape (registered trademark) No. 405: 24 mm width) was affixed to the grid-shaped cut surface and rubbed with an eraser for complete adhesion. Then, after performing the work of peeling the cellophane adhesive tape perpendicularly from the optical functional layer surface of the laminated polyester film for optics 5 times, the number of squares peeled off from the optical functional layer surface of the laminated polyester film for optics was counted visually. The adhesiveness between the optical functional layer and the base film was determined from the formula: In addition, what peeled partially among squares was also counted as the square which peeled, and was ranked according to the following references | standards.
Adhesiveness (%) = (1−number of peeled squares / 100) × 100
◎: 100% or optical functional layer material destruction ○: 99-90%
Δ: 89-70%
×: 69 to 0%

(8) Moisture and heat resistance The obtained laminated polyester film for optics was left in an environment of 80 ° C. and 95% RH for 48 hours in a high-temperature and high-humidity tank. Next, the laminated polyester film for optics was taken out and allowed to stand at room temperature and humidity for 12 hours. Then, the adhesiveness of an optical function layer and a base film was calculated | required by the method similar to said (7), and it ranked according to the following reference | standard.
◎: 100% or optical functional layer material destruction ○: 99-90%
Δ: 89-70%
×: 69 to 0%

(9) Appearance Metal (Al) deposition having a thickness of about 100 mm was performed on the hard coat layer surface of the optically laminated polyester film having a hard coat layer. The metal vapor-deposited surface was irradiated with a bromlite (VIDEO LIGHT VLG301 100V 300W LPL) in the range of about 10 ° to 45 ° with respect to the film surface, and evaluated in the following three stages by visual observation.
◯: There is no flickering feeling on the coating layer surface due to the coating surface micro-projections, and there is a clear mirror surface feeling. Δ: There is not much flickering feeling on the coating layer surface due to the coating surface micro-projections.
X: There is a flickering feeling on the coated layer surface due to the coated surface minute protrusions.

(Polymerization of urethane resin A-1 containing aliphatic polycarbonate polyol)
In a four-necked flask equipped with a stirrer, a Dimroth condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 43.75 parts by mass of 4,4-dicyclohexyl diisocyanate, 12.85 parts by mass of dimethylolbutanoic acid, several 153.41 parts by mass of polyhexamethylene carbonate diol having an average 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. It was confirmed that had reached the predetermined amine equivalent. Next, after the temperature of this reaction liquid was lowered to 40 ° C., 8.77 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 parts by mass of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, adjusted to 25 ° C., and stirred and mixed at 2000 rpm, the polyurethane prepolymer solution was added and dispersed in water. . Thereafter, a part of acetone and water was removed under reduced pressure to prepare an aqueous polyurethane resin dispersion (A-1) having a solid content of 35%. The obtained polyurethane resin (A-1) had a glass transition temperature of −30 ° C.

(Polymerization of urethane resin A-2 containing aliphatic polycarbonate polyol)
In a four-necked flask equipped with a stirrer, Dimroth cooler, nitrogen inlet tube, silica gel drying tube, and thermometer, 29.14 parts by mass of 4,4-dicyclohexyl diisocyanate, 7.57 parts by mass of dimethylolbutanoic acid, several An average molecular weight of 3000 polyhexamethylene carbonate diol 173.29 parts by mass, dibutyltin dilaurate 0.03 parts by mass, and 84.00 parts by mass of acetone as a solvent were added, and the mixture was stirred at 75 ° C. for 3 hours in a nitrogen atmosphere. It was confirmed that had reached the predetermined amine equivalent. Next, after the temperature of this reaction liquid was lowered to 40 ° C., 5.17 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 parts by mass of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, adjusted to 25 ° C., and stirred and mixed at 2000 rpm, the polyurethane prepolymer solution was added and dispersed in water. . Thereafter, a part of acetone and water was removed under reduced pressure to prepare an aqueous polyurethane resin dispersion (A-2) having a solid content of 35%.

(Polymerization of urethane resin A-3 containing aliphatic polycarbonate polyol as a constituent)
In a four-necked flask equipped with a stirrer, a Dimroth condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 43.75 parts by mass of 4,4-dicyclohexyl diisocyanate, 11.12 parts by mass of dimethylolbutanoic acid, hexane 1.97 parts by mass of diol, 143.40 parts by mass of polyhexamethylene carbonate diol having a number average molecular weight of 2000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were added, and 75 ° C. in a nitrogen atmosphere. The mixture was stirred for 3 hours to confirm that the reaction solution reached a predetermined amine equivalent. Next, after the temperature of this reaction liquid was lowered to 40 ° C., 8.77 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 parts by mass of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, adjusted to 25 ° C., and stirred and mixed at 2000 rpm, the polyurethane prepolymer solution was added and dispersed in water. . Thereafter, a part of acetone and water was removed under reduced pressure to prepare an aqueous polyurethane resin dispersion (A-3) having a solid content of 35%.

(Polymerization of silanol group-containing urethane resin A-4 containing aliphatic polycarbonate polyol as a constituent)
In a four-necked flask equipped with a stirrer, a Dimroth cooler, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 38.41 parts by mass of isophorone diisocyanate, 6.95 parts by mass of dimethylolpropanoic acid, and a number average molecular weight of 2000 Polyhexamethylene carbonate diol 158.999 parts by mass, dibutyltin dilaurate 0.03 parts by mass, and acetone 84.00 parts by mass as a solvent were added and stirred at 75 ° C. for 3 hours in a nitrogen atmosphere. It was confirmed that the equivalent amount was reached. Next, after cooling this reaction liquid to 40 degreeC, 4.37 mass parts of triethylamine was added, and the polyurethane prepolymer solution was obtained. Next, 3.84 parts by mass of γ- (aminoethyl) aminopropyltriethoxysilane, 1.80 parts by mass of 2-[(2-aminoethyl) amino] ethanol and 450 parts by mass of water were added to obtain a polyurethane prepolymer solution. Was dropped and dispersed in water. Thereafter, a part of acetone and water was removed under reduced pressure to prepare a silanol group-containing polyurethane resin aqueous dispersion (A-4) having a solid content of 30%.

(Polymerization of urethane resin A-5 containing aliphatic polycarbonate polyol as a constituent)
A polyurethane resin aqueous dispersion having a solid content of 35% was prepared in the same manner except that the polyhexamethylene carbonate diol having a number average molecular weight of 2000 in the polyurethane resin (A-1) was changed to a polyhexamethylene carbonate diol having a number average molecular weight of 1000. A-5) was obtained.

(Polymerization of urethane resin A-6 containing aliphatic polycarbonate polyol as a constituent)
A polyurethane resin aqueous dispersion having a solid content of 35% was prepared in the same manner except that the polyhexamethylene carbonate diol having a number average molecular weight of 2000 in the polyurethane resin (A-1) was changed to a polyhexamethylene carbonate diol having a number average molecular weight of 5000. A-6) was obtained.

(Polymerization of urethane resin containing polyester polyol as component A-7)
A polyurethane resin aqueous dispersion (A-7) having a solid content of 35% was prepared in the same manner except that the polyhexamethylene carbonate diol having a number average molecular weight of 2000 in the polyurethane resin (A-1) was changed to a polyester diol having a number average molecular weight of 2000. )

(Polymerization polymerization of polyether resin with polyether polyol A-8)
A polyurethane resin aqueous dispersion (A-) having a solid content of 35% was prepared in the same manner except that the polyhexamethylene carbonate diol having a number average molecular weight of 2000 in the polyurethane resin (A-1) was changed to a polyether diol having a number average molecular weight of 2000. 8) was obtained.

(Polymerization of block polyisocyanate crosslinking agent B-1)
52.21 parts by mass of a polyisocyanate compound having an isocyanurate structure using hexamethylene diisocyanate as a raw material (Duranate (registered trademark) TPA-100, manufactured by Asahi Kasei Chemicals Corporation) in a flask equipped with a stirrer, a thermometer, and a reflux condenser Was added dropwise with 20.72 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 1000) and kept at 70 ° C. for 5 hours in an atmosphere. Thereafter, 27.08 parts by mass of 3,5-dimethylpyrazole (dissociation temperature: 120 ° C., boiling point: 218 ° C.) was added dropwise. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate group had disappeared, 25 parts by mass of dipropylene glycol dimethyl ether and 125 parts by mass of water were added, and the mixture was stirred at 30 ° C. at a high speed. A block polyisocyanate aqueous dispersion (B-1) was obtained.

(Polymerization of block polyisocyanate crosslinking agent B-2)
In a flask equipped with a stirrer, a thermometer, and a reflux condenser, 52.54 parts by mass of a polyisocyanate compound having a biuret structure made from hexamethylene diisocyanate (manufactured by Asahi Kasei Chemicals Corporation, Duranate (registered trademark) 24A-100) Polyethylene glycol monomethyl ether (average molecular weight 1000) was maintained at 70 ° C. for 5 hours in an atmosphere of 19.78 parts by mass. Thereafter, 27.67 parts by mass of 3,5-dimethylpyrazole (dissociation temperature: 120 ° C., boiling point: 218 ° C.) was added dropwise. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate group had disappeared, 25 parts by mass of dipropylene glycol dimethyl ether and 125 parts by mass of water were added, and the mixture was stirred at 30 ° C. at a high speed. A block polyisocyanate aqueous dispersion (B-2) was obtained.

(Polymerization of block polyisocyanate crosslinking agent B-3)
A flask equipped with a stirrer, thermometer, reflux condenser, and polyisocyanate compound having an isocyanurate structure using hexamethylene diisocyanate as a raw material (manufactured by Asahi Kasei Chemicals Corporation, Duranate TPA-100) 66.04 parts by mass, N-methyl 25.19 parts by mass of 3,5-dimethylpyrazole (dissociation temperature: 120 ° C., boiling point: 218 ° C.) was added dropwise to 17.50 parts by mass of pyrrolidone, and kept at 70 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, 5.27 parts by mass of dimethylolpropanoic acid was added dropwise. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate group disappeared, 5.59 parts by mass of N, N-dimethylethanolamine and 132.5 parts by mass of water were added, and the solid content was 40% by mass. A block polyisocyanate aqueous dispersion (B-3) was obtained.

(Polymerization of block polyisocyanate crosslinking agent B-4)
Except that 3,5-dimethylpyrazole (dissociation temperature: 120 ° C., boiling point: 218 ° C.) of the block polyisocyanate aqueous dispersion (B-1) was changed to diethyl malonate (dissociation temperature: 120 ° C., boiling point 199 ° C.). In the same manner, a block polyisocyanate aqueous dispersion (B-4) having a solid content of 40% was obtained.

(Polymerization of block polyisocyanate crosslinking agent B-5)
Except for changing 3,5-dimethylpyrazole (dissociation temperature: 120 ° C., boiling point: 218 ° C.) of the block polyisocyanate aqueous dispersion (B-1) to methyl ethyl ketoxime (dissociation temperature: 140 ° C., boiling point: 152 ° C.). In the same manner, a block polyisocyanate aqueous dispersion (B-5) having a solid content of 40% was obtained.

(Polymerization of block polyisocyanate crosslinking agent B-6)
Except that 3,5-dimethylpyrazole (dissociation temperature: 120 ° C., boiling point: 218 ° C.) of the block polyisocyanate aqueous dispersion (B-3) was changed to methyl ethyl ketoxime (dissociation temperature: 140 ° C., boiling point: 152 ° C.). In the same manner, a block polyisocyanate aqueous dispersion (B-6) having a solid content of 40% was obtained.

Example 1
(1) Adjustment of coating liquid The following coating agent was mixed and the coating liquid was created.
Water 53.65% by mass
Isopropanol 30.00% by mass
Polyurethane resin (A-1) 11.29% by mass
Block polyisocyanate aqueous dispersion (B-1) 4.23 mass%
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicone-based, solid content concentration of 100% by mass)

(2) Production of Easy-Adhesive Polyester Film PET film pellets having an intrinsic viscosity of 0.62 dl / g and containing substantially no particles as a film raw material polymer at 135 ° C. under reduced pressure of 133 Pa for 6 hours Dried. Thereafter, the sheet was supplied to an extruder, melted and extruded into a sheet at about 280 ° C., and rapidly cooled and solidified on a rotating cooling metal roll maintained at a surface temperature of 20 ° C. to obtain an unstretched PET sheet.

The 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 having a difference in peripheral speed to obtain a uniaxially stretched PET film.

Subsequently, after apply | coating the said coating liquid on the single side | surface of PET film by the roll coat method, it dried at 80 degreeC for 20 second. The final coating amount (after biaxial stretching) was adjusted so that the coating amount after drying was 0.15 g / m ² . Subsequently, with a tenter, the film was stretched 4.0 times in the width direction at 120 ° C., and the heat treatment zone was subjected to heat treatment at a maximum temperature of 230 ° C. for 20 seconds with a fixed length in the width direction. A relaxation treatment in the width direction of 3% was performed at 10 ° C. for 10 seconds. Both ends were trimmed, wound up by a winding device, further divided into two in the width direction and slitted to obtain a film roll having a width of 1300 mm, a film length of 3000 m, and a film thickness of 100 μm. Table 1 shows the evaluation results of the obtained easily adhesive polyester film.

(3) Production of optical laminated polyester film (Optical laminated polyester film having a hard coat layer)
A hard coat layer-forming coating solution (E) having the following composition was applied to the coating layer surface of the easy-adhesive polyester film using a # 10 wire bar and dried at 70 ° C. for 1 minute to remove the solvent. Next, the film coated with the hard coat layer was irradiated with 300 mJ / cm ² ultraviolet rays using a high-pressure mercury lamp to obtain an optical laminated polyester film having a hard coat layer having a thickness of 5 μm.
Hard coat layer forming coating solution (E)
Methyl ethyl ketone 65.00% by mass
Photo-curing acrylic resin 27.20% by mass
(New Nakamura Chemical Co., Ltd. NK Ester (registered trademark) A-DPH)
Photocurable acrylic resin 6.80% by mass
(NK Naka Ester (registered trademark) A-400 manufactured by Shin-Nakamura Chemical Co., Ltd.)
Photopolymerization initiator 1.00% by mass
(Irgacure (registered trademark) 184 manufactured by BASF Japan Ltd.)

(Optical laminated polyester film with photocured urethane / acrylic layer)
About 5 g of the following photocurable acrylic coating solution is placed on a 1 mm thick SUS plate (SUS304) kept clean so that the coating layer surface of the easy-adhesive polyester film sample and the photocurable acrylic coating solution are in contact with each other. The photocuring urethane / acrylic coating liquid (F) was stretched and stretched with a manually loaded rubber roller having a width of 10 cm and a diameter of 4 cm from above the easy-adhesive polyester film sample. Next, 500 mJ / cm ² of ultraviolet rays was irradiated from the easy-adhesive polyester film surface side using a high-pressure mercury lamp to cure the photocurable urethane / acrylic resin. A film sample having a 20 μm-thick photocured urethane / acrylic layer was peeled from the SUS plate to obtain a laminated polyester film for optics.
Light curable urethane / acrylic coating solution (F)
Photo-curing acrylic resin 67.00% by mass
(NK Naka Ester (registered trademark) A-BPE-4 manufactured by Shin-Nakamura Chemical Co., Ltd.)
Light curable urethane / acrylic resin 20.00% by mass
(Shin Nakamura Chemical U-6HA (product name))
Photo-curing acrylic resin 10.00% by mass
(NK Naka Ester (registered trademark) AMP-10G manufactured by Shin-Nakamura Chemical Co., Ltd.)
Photopolymerization initiator 3.00% by mass
(Irgacure 184 manufactured by BASF Japan Ltd.)

(Optical laminated polyester film with photocured acrylic layer)
The optical laminated polyester film having a photocured urethane / acrylic layer is optically similar except that the photocurable urethane / acrylic coating solution (F) is changed to a photocurable acrylic coating solution (G). A laminated polyester film was obtained.
Photo-curing acrylic coating solution (G)
Photo-curing acrylic resin 77.00% by mass
(New Nakamura Chemical Co., Ltd. NK Ester A-BPE-4)
Photo-curing acrylic resin 20.00% by mass
(New Nakamura Chemical Co., Ltd. NK Ester AMP-10G)
Photopolymerization initiator 3.00% by mass
(Irgacure 184 manufactured by BASF Japan Ltd.)

Comparative Example 1
An easy-adhesive polyester film and an optical laminated polyester film were obtained in the same manner as in Example 1 except that the coating solution was changed to the following.
Water 53.04 mass%
Isopropanol 30.00% by mass
Polyurethane resin (A-1) 16.13% by mass
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicone-based, solid content concentration of 100% by mass)

Comparative Example 2
An easy-adhesive polyester film and an optically laminated polyester film were obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion was changed to the block polyisocyanate aqueous dispersion (B-5).

Comparative Example 3
An easy-adhesive polyester film and an optically laminated polyester film were obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion was changed to the block polyisocyanate aqueous dispersion (B-6).

Comparative Example 4
The block polyisocyanate aqueous dispersion was changed to a polyisocyanate aqueous dispersion having an isocyanurate structure using hexamethylene diisocyanate as a raw material (Duranate (registered trademark) WT30-100, manufactured by Asahi Kasei Chemicals Corporation). An easy-adhesive polyester film and an optically laminated polyester film were obtained in the same manner as in Example 1 except that the coating was performed after 24 hours.

Example 2
An easily adhesive polyester film and an optically laminated polyester film were obtained in the same manner as in Example 1 except that the polyurethane resin was changed to the polyurethane resin (A-5).

Example 3
An easily adhesive polyester film and an optically laminated polyester film were obtained in the same manner as in Example 1 except that the polyurethane resin was changed to the polyurethane resin (A-6).

Example 4
An easy-adhesive polyester film and an optical laminated polyester film were obtained in the same manner as in Example 1 except that the coating solution was changed to the following.
Water 53.24% by mass
Isopropanol 30.00% by mass
Polyurethane resin (A-1) 14.51% by mass
Block polyisocyanate aqueous dispersion (B-1) 1.42% by mass
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicone-based, solid content concentration of 100% by mass)

Example 5
An easy-adhesive polyester film and an optical laminated polyester film were obtained in the same manner as in Example 1 except that the coating solution was changed to the following.
Water 53.46% by mass
Isopropanol 30.00% by mass
Polyurethane resin (A-1) 12.90% by mass
Block polyisocyanate aqueous dispersion (B-1) 2.81% by mass
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicone-based, solid content concentration of 100% by mass)

Example 6
An easy-adhesive polyester film and an optical laminated polyester film were obtained in the same manner as in Example 1 except that the coating solution was changed to the following.
54.06% by weight of water
Isopropanol 30.00% by mass
Polyurethane resin (A-1) 8.06% by mass
Block polyisocyanate aqueous dispersion (B-1) 7.05 mass%
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicone-based, solid content concentration of 100% by mass)

Example 7
An easy-adhesive polyester film and an optical laminated polyester film were obtained in the same manner as in Example 1 except that the coating solution was changed to the following.
Water 54.66% by mass
Isopropanol 30.00% by mass
Polyurethane resin (A-1) 3.23% by mass
Block polyisocyanate aqueous dispersion (B-1) 11.28% by mass
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicone-based, solid content concentration of 100% by mass)

Example 8
An easy-adhesive polyester film and an optical laminated polyester film were obtained in the same manner as in Example 1 except that the coating solution was changed to the following.
Water 54.87 mass%
Isopropanol 30.00% by mass
Polyurethane resin (A-1) 1.61% by mass
Block polyisocyanate aqueous dispersion (B-1) 12.69 mass%
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.07% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicone-based, solid content concentration of 100% by mass)

Example 9
An easily adhesive polyester film and an optical laminated polyester film were obtained in the same manner as in Example 1 except that the polyurethane resin was changed to the polyurethane resin (A-2).

Example 10
An easily adhesive polyester film and an optically laminated polyester film were obtained in the same manner as in Example 1 except that the polyurethane resin was changed to the polyurethane resin (A-3).

Example 11
An easily adhesive polyester film and an optically laminated polyester film were obtained in the same manner as in Example 1 except that the polyurethane resin was changed to a silanol group-containing polyurethane resin (A-4).

Example 12
An easy-adhesive polyester film and an optically laminated polyester film were obtained in the same manner as in Example 1 except that the polyurethane resin was changed to the polyurethane resin (A-7).

Example 13
An easy-adhesive polyester film and an optically laminated polyester film were obtained in the same manner as in Example 1 except that the polyurethane resin was changed to the polyurethane resin (A-8).

Example 14
An optical laminated polyester film was obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion (B-1) was changed to the block polyisocyanate aqueous dispersion (B-2).

Example 15
An optical laminated polyester film was obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion (B-1) was changed to the block polyisocyanate aqueous dispersion (B-3).

Example 16
An optical laminated polyester film was obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion (B-1) was changed to the block polyisocyanate aqueous dispersion (B-4).

Example 17
An optical laminated polyester film was obtained in the same manner as in Example 1 except that a coating solution was prepared and applied after 24 hours.

Example 18
An easy-adhesive polyester film and an optical laminated polyester film were obtained in the same manner as in Example 1 except that the coating solution was changed to the following.
61.83% by mass of water
Isopropanol 30.00% by mass
Polyurethane resin (A-1) 5.64% by mass
Block polyisocyanate aqueous dispersion (B-1) 2.12% by mass
0.35% by mass of particles
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
0.04% by mass of particles
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant 0.02% by mass
(Silicone-based, solid content concentration of 100% by mass)

The easy-adhesive polyester film of the present invention is excellent in adhesion with an optical functional layer and adhesion under high temperature and high humidity (moisture and heat resistance), and is therefore particularly suitable for optical applications and is mainly used for displays and the like. It is suitable as a base film for optical functional films such as a film and an antireflection film, a light diffusion sheet, a lens sheet, a near-infrared shielding film, a transparent conductive film, and an antiglare film.

Claims (7)

A polyester film having a coating layer on at least one side,
The coating layer is mainly composed of urethane resin and blocked isocyanate,
An easy-adhesive polyester film having a dissociation temperature of the blocked isocyanate of 130 ° C or lower and a boiling point of the blocking agent of 180 ° C or higher. 2. The easily adhesive polyester film according to claim 1, wherein the urethane resin is a urethane resin containing an aliphatic polycarbonate polyol as a constituent component. In the infrared spectrum of the coating layer, the ratio (A ₁₄₆₀ ) of the peak absorbance near 1460 cm ⁻¹ derived from the aliphatic polycarbonate component to the absorbance (A ₁₅₃₀ ) peak near 1530 cm ⁻¹ derived from the urethane component (A ₁₅₃₀ ) The easily adhesive polyester film according to claim 2, wherein ₁₄₆₀ / A ₁₅₃₀ ) is 0.40 to 1.55. The easily adhesive polyester film according to any one of claims 1 to 3, wherein a mass ratio of urethane resin to blocked isocyanate (urethane resin / block isocyanate) in the coating layer is 1/9 to 9/1. The easily adhesive polyester film according to any one of claims 1 to 4, wherein the haze of the polyester film is 2.0% or less. The coating layer of the easily adhesive polyester film according to any one of claims 1 to 5, wherein the coating layer is at least selected from a hard coat layer, a light diffusion layer, a lens layer, an electromagnetic wave absorption layer, a near infrared ray blocking layer, and a transparent conductive layer. An optical laminated polyester film obtained by laminating one optical functional layer. An easily adhesive polyester film roll formed by winding up the easily adhesive polyester film according to any one of claims 1 to 5.