TWI411634B - Adhesive polyester film - Google Patents

Abstract

Disclosed is a highly adhesive polyester film which exhibits excellent adhesion to an optical functional layer under high temperature high humidity conditions. The highly adhesive polyester film has a coating layer, which is mainly composed of a crosslinking agent and a urethane resin that contains an aliphatic polycarbonate polyol as a component, on at least one surface of a polyester film. The ratio of the absorbance around 1460 cm-1 ascribed to the aliphatic polycarbonate component relative to the absorbance around 1530 cm-1 ascribed to the urethane component is 0.40-1.55 as determined by infrared spectrometry.

Description

Easy adhesive polyester film

The present invention relates to an easily bondable polyester film which is excellent in adhesion and moist heat resistance. In particular, it relates to an easy-adhesive polyester film mainly used as a hard coating film, an antireflection film, a light diffusion sheet, a lens sheet, a near-infrared occlusion film, a transparent conductive film, and an anti-glare for a display or the like. The substrate of an optical functional film such as a film is extremely suitable.

A substrate which is generally used as an optical functional film as a member of a liquid crystal display (LCD), is a transparent thermoplastic resin film which is made of polyethylene terephthalate (PET), acrylic, or polycarbonate (PC). ), triacetyl cellulose (TAC), polyolefin, etc.

When the thermoplastic resin film is used as a substrate of various optical functional films, a functional layer for various uses is laminated. For example, in a liquid crystal display (LCD), a protective film (hard coat layer) for preventing damage of a surface, an antireflection layer (AR layer) for preventing reflection of external light, and light collection or diffusion for light can be exemplified. A functional layer such as a germanium layer or a light diffusing layer that enhances brightness. Among such substrates, 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, in the case of a biaxially oriented polyester film or a biaxially oriented polyimide film as a biaxially oriented thermoplastic film, since the surface of the film is highly crystallized, there is a lack of adhesion to various coatings, adhesives, inks, and the like. Disadvantages. Therefore, there have been proposals for a method of providing easy adhesion in various ways on the surface of the biaxially oriented polyester film.

For example, it is generally known to provide a coating layer containing various resins such as polyester, acrylic, polyurethane, acrylic graft polyester, and the like as a main constituent component on the surface of the polyester film of the substrate. The method of easy adhesion of the film. In the coating method, industrially, a film coating aqueous solution is applied onto a polyester film before completion of crystal alignment, and the aqueous coating liquid contains a dispersion of a solution or a resin in which the resin is dispersed in a dispersion medium. a method in which the body is stretched in at least one axial direction after drying, followed by heat treatment to complete the alignment of the polyester film (so-called on-line coating method); or after application of the polyester film, coating of water-based or solvent-based coating After the liquid is applied to the film, it is dried (so-called off-line coating method).

A display such as an LCD or a PDP, or a portable device using a hard coat film as a member can be used in various environments, both indoors and outdoors. In particular, in the case of a portable device, there is a case where it is required to withstand the heat and humidity resistance of a bathroom, a hot and humid area, and the like. In the optical functional film used for such use, high adhesion without interlayer peeling is required even under high temperature and high humidity. Therefore, in the following patent documents, there is disclosed an easily adhesive polyester film which is obtained by adding a resin having a high glass transition temperature or a crosslinking agent to a coating liquid, and is hardened by formation of a coating layer by an in-line coating method. The coating layer is formed in the coating layer resin to provide moist heat resistance.

Prior technical literature

Patent literature

Patent Document 1: JP-A-2000-141574

Patent Document 2: Patent No. 3900191

Patent Document 3: JP-A-2007-253512

In order to reduce the load on the global environment, we expect to have a longer service life than the traditional home appliances of the display. Therefore, it has been considered that even in an optical functional film used as a member, it is necessary to maintain adhesiveness for a long period of time even under high temperature and high humidity. However, the easy-adhesive film disclosed in the above-mentioned patent document exhibits good adhesion at the beginning, but it is used for a long period of time under high temperature and high humidity, but the decrease in adhesion strength cannot be avoided. Due to the decrease in the adhesion, there is a problem that it is considered that the initial performance cannot be maintained for a long period of time.

In addition, as the photocurable resin constituting the optical functional layer, a variety of resin composition types having different refractive indices or intensities are gradually used along with the precision of the optical design. However, in the above-mentioned easy-adhesive film, although it has high adhesion to a specific resin composition type, it is still easy to use a film which is highly versatile, even with respect to various photocurable resins. It can also show the same degree of closeness.

In view of the above problems, the present invention provides an easy-adhesive polyester film which has almost no deterioration in adhesion under high temperature and high humidity which is considered to be unavoidable before, and which is excellent in various optical resin compositions. The adhesion.

In addition, the adhesiveness under high temperature and high humidity in the present invention refers to a tool guide which is placed at 80 ° C, 95% RH, and 48 hours after laminating a photocurable resin layer or the like, and using a gap of 2 mm. Passing through the photo-curable resin layer, 100 mesh-shaped cuts reaching the base film are formed on the photo-curable resin layer, and then the cellophane adhesive tape is adhered to the lattice-shaped cut surface, and wiped with an eraser. The adhesion between the same place and the strength of the same place is 5 times, which is a stricter criterion than the evaluation method described in JIS K5600-5-6, which is generally used. The problem is that the adhesion between the high-temperature and high-humidity shows the same adhesion as the initial adhesion.

In order to solve the above-mentioned problems, the present inventors have conducted research on the above-mentioned problems. As a result, firstly, a polyester film having a coating layer on at least one side thereof, which is an aminocarboxylic acid having an aliphatic polycarbonate polyol as a constituent component, has been found. The ester resin and the crosslinking agent are used as main components, and the absorbance (A ₁₄₆₀ ) in the vicinity of ₁₄₆₀ cm ^-1 from the aliphatic polycarbonate component and 1530 cm from the urethane component are in the infrared spectrum of the coating layer. The ratio of the absorbance (A ₁₅₃₀ ) in the vicinity of ^-1 (A ₁₄₆₀ /A ₁₅₃₀ ) is 0.40 to 1.55, whereby the adhesion under high temperature and high humidity can be improved, and thus the present invention has been completed.

That is, the subject can be achieved by the following solutions.

(1) An easy-adhesive polyester film characterized by a polyester film having a coating layer on at least one side, the coating layer being a urethane resin which makes an aliphatic polycarbonate polyol into a constituent component and the crosslinking agent as a main component, the coating layer of the infrared spectroscopic spectrum of the absorbance at 1460 cm ^-1 from the vicinity of the aliphatic polycarbonates of component (A ₁₄₆₀₎ and the ester component of from 1530cm ^-1 urethane The ratio of the nearby absorbance (A ₁₅₃₀ ) (A ₁₄₆₀ /A ₁₅₃₀ ) is 0.40 to 1.55.

(2) The easy-adhesive polyester film, wherein the crosslinking agent is selected from the group consisting of a melamine crosslinking agent, an isocyanate crosslinking agent, a carbodiimide crosslinking agent, and an oxazoline crosslinking agent. At least one crosslinking agent.

(3) The above-mentioned easy-adhesive polyester film in which the ratio of the urethane resin which is a constituent component of the aliphatic polycarbonate in the coating layer and the crosslinking agent (urethane resin) /crosslinking agent) is from 1/9 to 9/1.

(5) A laminated polyester film which is applied to the coating layer of the easy-contact polyester film, and the laminate is selected from the group consisting of a hard coat layer, a light diffusion layer, a lens layer, an electromagnetic wave absorbing layer, a near-infrared ray interrupting layer, and a transparent layer. An optical functional layer of at least one of the conductive layers.

(6) An easy-adhesive polyester film roll obtained by winding the above-mentioned optical easy-adhesive polyester film.

The easy-adhesive polyester film of the present invention is excellent in adhesion to various optical functional layers (humid heat resistance) under high temperature and high humidity. Therefore, in a preferred embodiment, the adhesion under the above-described high temperature and high humidity treatment can maintain the same effect as the original adhesion.

(Polyester film)

In the polyester resin constituting the substrate in the present invention, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polyterephthalate can be used. a methyl ester, and a diol component such as diethylene glycol, neopentyl glycol, or polyalkylene glycol as a copolymerization component; or adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2 A polyester resin obtained by copolymerizing a dicarboxylic acid component such as 6-naphthalenedicarboxylic acid or the like.

The polyester resin which can be suitably used in the present invention is mainly composed of at least one of polyethylene terephthalate, polybutylene terephthalate, polybutylene terephthalate and polyethylene naphthalate. Composition. Among these polyester resins, polyethylene terephthalate is preferred from the viewpoint of balance between physical properties and cost. Moreover, these polyester films can improve chemical resistance, heat resistance, mechanical strength, etc. under biaxial stretching.

Further, the biaxially stretched polyester film may be either a single layer or a composite layer. Moreover, as long as the effect of the present invention can be achieved, various additives may be contained in the polyester resin as needed in the respective layers. The additive may, for example, be an antioxidant, a light stabilizer, an antigelling agent, an organic wetting agent, an antistatic agent, an ultraviolet absorber, a surfactant, or the like.

Further, in order to improve the workability such as lubricity, winding property, and antiblocking property of the film, or abrasion resistance such as abrasion resistance and scratch resistance, the polyester film contains inert particles. situation. However, since the film of the present invention uses a base film as an optical member, it is required to maintain high transparency and excellent workability. Specifically, in the case of using a base film as an optical member, it is preferred that the optically easy-to-adherent polyester film has a total light transmittance of 85% or more, more preferably 87% or more, and still preferably 88%. The above is particularly preferably 89% or more, and most preferably 90% or more.

Further, in order to have high sharpness, the content of inert particles in the base film is preferably as small as possible. Therefore, a preferred embodiment is a multilayer structure containing particles only in the surface layer of the film, or substantially no particles in the film, but contains fine particles only in the coating layer.

In particular, from the viewpoint of transparency, in the case where the polyester film does not substantially contain inert particles, in order to improve the handleability of the film, it is preferred to contain the inorganic and/or heat-resistant polymer particles in the aqueous coating liquid. Among them, irregularities are formed on the surface of the coating layer.

In addition, the term "substantially free of inert particles" means, for example, in the case of inorganic particles, when quantitatively analyzing elements derived from particles by fluorescence X-ray analysis, it means 50 ppm or less, preferably 10 ppm or less, and optimal. To detect the content below the limit. This means that even if the particles are not actively added to the base film, the contamination component from the foreign matter or the dirt adhering to the line or the device during the manufacturing step of the raw resin or film is peeled off. Mixed into the film.

(coating layer)

The easy-adhesive polyester film of the present invention has a coating layer formed by using an aliphatic polycarbonate polyol as a constituent urethane resin and a crosslinking agent as a main component in infrared spectroscopy. The ratio of the absorbance (A ₁₄₆₀ ) in the vicinity of ₁₄₆₀ cm ^-1 from the aliphatic polycarbonate component to the absorbance (A ₁₅₃₀ ) in the vicinity of ₁₅₃₀ cm ^-1 from the urethane component of the coating layer ( A ₁₄₆₀ / A ₁₅₃₀ ) is 0.40 to 1.55, which is extremely important. Here, the term "main component" means 50% by mass or more, and more preferably 70% by mass or more, based on the total solid content of the coating layer.

As described in the above-mentioned Patent Documents 1 to 3, in the prior art, from the viewpoint of improving the heat and humidity resistance of the coating layer, it has been considered that the resin or the crosslinked structure having a high glass transition temperature is actively formed in the formation of the coating layer. The introduction is expected to be made into a tough coating layer. However, in the present invention, it has been found that by combining a polyurethane resin and a crosslinking agent and controlling the absorbance of the infrared spectroscopy to a certain range, there is a remarkable effect of improving the adhesion under high temperature and high humidity. Thus, the present invention has been completed. Although the inventors of the present invention have not yet known the mechanism of action for improving the adhesion under high temperature and high humidity, the inventors of the present invention have considered the following.

In the case of the base film-layered optical functional layer, strong stress is generated between the optical functional layer and the coating layer by shrinkage during curing of the photo-curable resin constituting the optical functional layer or expansion during high-temperature and high-humidity treatment. When such a laminated film is subjected to high temperature and high humidity, the coating layer is deteriorated by dissolution, expansion or hydrolysis by a solvent contained in the photocurable resin. I believe that the result is that the above stress cannot be tolerated, and the optical functional layer is peeled off, and the adhesion is lowered. Therefore, in order to highly maintain the adhesion under high temperature and high humidity, it is desirable to make the coating layer to be strongly crosslinked, or to provide not only hydrolysis resistance, but also flexibility to withstand the above stress. However, light is a problem of being soft, but still having a viewpoint of solvent resistance or strength. Therefore, it is most desirable to have these opposite characteristics coexist.

In the present invention, a coating layer containing a urethane resin having a fatty polycarbonate polyol as a constituent component and a crosslinking agent as a main component is derived from an aliphatic group by infrared spectrometry. The ratio of the absorbance (A ₁₄₆₀ ) in the vicinity of ₁₄₆₀ cm ^-1 of the polycarbonate component to the absorbance (A ₁₅₃₀ ) in the vicinity of ₁₅₃₀ cm ^-1 from the urethane component (A ₁₄₆₀ /A ₁₅₃₀ ) is 0.40 to 1.55. The above characteristics can be coexisted. That is, the solvent resistance is provided by the crosslinking agent, and at the same time, the aliphatic polycarbonate component having hydrolysis resistance and flexibility and the urethane component having a strong hardness are coexisted at a set ratio. , the coexistence of the above characteristics can be sought. In view of this, it is possible to relax the stress during curing of the photocurable resin or the expansion during the high-temperature and high-humidity treatment, so that various types of photocurable resins can be obtained, and good adhesion can be obtained even in the case of In the subsequent high-temperature and high-humidity environment, deterioration of the coating layer such as dissolution, swelling, or hydrolysis caused by the solvent remaining in the coating layer or the diluted monomer can be prevented.

Here, the absorbance (A ₁₄₆₀ ) in the vicinity of ₁₄₆₀ cm ^-1 is a 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 ) in the vicinity of ₁₄₆₀ cm ^-1 depends on the amount of the aliphatic polycarbonate polyol component constituting the urethane resin present in the coating layer. On the one hand, the absorbance (A ₁₅₃₀ ) around ₁₅₃₀ cm ^-1 is derived from the bending vibration characteristic of the NH bond contained in the urethane component. Therefore, the magnitude of the absorbance (A ₁₅₃₀ ) in the vicinity of ₁₅₃₀ cm ^-1 depends on the amount of the urethane component (the number of urethane bonds) constituting the urethane resin present in the coating layer. Further, in the case where an isocyanate crosslinking agent is used as the crosslinking agent, the amount of absorbance (A ₁₅₃₀ ) in the vicinity of ₁₅₃₀ cm ^-1 depends on the amine which is the sum of the amount of the urethane resin and the crosslinking agent present in the coating layer. The amount of carbamate component (number of urethane bonds). Therefore, the absorbance ratios (A ₁₄₆₀ /A ₁₅₃₀ ) are those in which two components each having different characteristics coexist at a specific ratio. In the present invention, the ratio (A ₁₄₆₀ /A ₁₅₃₀ ) is from 0.40 to 1.55, and the lower limit of the ratio (A ₁₄₆₀ /A ₁₅₃₀ ) is preferably 0.45, more preferably 0.50. Further, the upper limit of the ratio (A ₁₄₆₀ /A ₁₅₃₀ ) is preferably 1.50, more preferably 1.40, still more preferably 1.30, and particularly preferably 1.20. When the ratio (A ₁₄₆₀ /A ₁₅₃₀ ) is less than 0.40, the tough urethane component becomes excessive, and the heat and humidity resistance is lowered due to a decrease in stress relaxation of the coating layer. Moreover, when the ratio (A ₁₄₆₀ /A ₁₅₃₀ ) is more than 1.55, the aliphatic component of the soft aliphatic polycarbonate becomes excessive, and the solvent resistance of the coating layer is lowered, so that the moist heat resistance is lowered.

According to the present invention, in the above aspect, adhesion to the lens layer and further to other optical functional layers (heat and humidity resistance) can be improved under high temperature and high humidity. Furthermore, the constitution of the present invention will be described in detail below.

(urethane resin)

The urethane resin of the present invention contains at least a polyalcohol component and a polyisocyanate component as a constituent component, and further contains a chain extender as needed. In the urethane resin of the present invention, the constituent components are mainly polymer compounds copolymerized by a urethane bond. In the feature of the present invention, the constituent component of the urethane resin is an aliphatic polycarbonate polyol. When the coating layer of the present invention contains a urethane resin having an aliphatic polycarbonate as a constituent component, moist heat resistance can be improved. Further, the constituent components of the urethane resin can be specified by nuclear magnetic resonance (NMR) analysis or the like.

The diol component which is a constituent component of the urethane resin of the present invention is required to contain an aliphatic polycarbonate polyol which is excellent in heat resistance and hydrolysis resistance. In the optical use of the present invention, it is preferred to use an aliphatic polycarbonate polyol from the viewpoint of preventing yellowing.

The aliphatic polycarbonate diol, an aliphatic polycarbonate triol or the like may be mentioned as the aliphatic polycarbonate polyol, and an aliphatic polycarbonate diol may be used as appropriate. The aliphatic polycarbonate diol which is a constituent component of the urethane resin of the present invention is, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5- Pentandiol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol And one or more of glycols such as dipropylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; and, for example, by using dimethyl carbonate or diphenyl carbonate, An aliphatic polycarbonate diol or the like is obtained by reacting a carbonate such as ethylene carbonate or phosgene. The number average molecular weight of the aliphatic polycarbonate diol is preferably from 1,500 to 4,000, more preferably from 2,000 to 3,000. 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 small. Therefore, in order to set the ratio (A ₁₄₆₀ /A ₁₅₃₀ ) to the above range, it is preferred to control the number average molecular weight of the aliphatic polycarbonate diol to be in the above range.

When the number average molecular weight of the aliphatic polycarbonate diol is large, the absorbance (A ₁₄₆₀ ) in the vicinity of ₁₄₆₀ cm ^-1 from the aliphatic polycarbonate component increases, and the solvent resistance decreases as the aliphatic component increases. There is a situation in which the adhesion is lowered. When the number average molecular weight of the aliphatic polycarbonate diol is small, the tough urethane component increases, and the stress due to shrinkage or expansion of the photocurable resin or the like cannot be alleviated, and the adhesion may be lowered. .

The polyisocyanate which is a constituent component of the urethane resin of the present invention may, for example, be an aromatic aliphatic diisocyanate such as dimethylene diisocyanate or isophorone diisocyanate. And alicyclic diisocyanates such as 4,4-dicyclohexylmethyl diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, hexamethylene diisocyanate, and diisocyanide An aliphatic diisocyanate such as 2,2,4-trimethylhexamethylene acid or a polyisocyanate obtained by preliminarily adding such a compound to trimethylolpropane or the like in a single or plural form. In the case of using an aromatic isocyanate, there is a problem of yellowing, and in the case of optical use requiring high transparency, there is an inappropriate situation. In addition, since it is a tough coating film, the stress due to shrinkage or expansion of the photocurable resin or the like cannot be alleviated, and the adhesion is lowered.

This ratio (A ₁₄₆₀ /A ₁₅₃₀ ) can also be adjusted by chain extenders. The chain extender which can be used in the invention may, for example, be a glycol such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol or 1,6-hexanediol; glycerin, Polyvalent alcohols such as trimethylolpropane and pentaerythritol; ethylenediamine, hexamethylenediamine, and hexahydropyridyl Such as diamines; amine alcohols such as monoethanolamine and diethanolamine; diethanol sulfides such as diethylene glycol sulphide; or water. However, when a chain extender having a short main chain is used, the absorbance (A ₁₅₃₀ ) in the vicinity of ₁₅₃₀ cm ^-1 from the urethane component increases, and the flexibility of the coating layer may be lowered. Therefore, the chain extender is preferably the main chain. Further, from the viewpoint of providing flexibility of the coating layer, a chain extender of a diol or a diamine having a carbon number of 4 to 10 in the main chain is preferred. From the viewpoint of these, the chain extender used in the present invention is suitably 1,4-butanediol, 1,6-hexanediol, hexamethylenediamine or the like.

The coating layer of the present invention is preferably a water-based coating liquid and is provided by an in-line coating method to be described later. Therefore, it is desirable for the urethane resin of the present invention to be water soluble. Further, the above "water-soluble" means water or an aqueous solution of less than 50% by mass based on the water-soluble organic solvent is dissolved.

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

In order to introduce a carboxylic acid (salt) based on a urethane resin, for example, a polyalcohol component having a carboxylic acid group such as dimethylolpropionic acid or dimethylolbutyric acid is introduced as a copolymer component. It is neutralized with a salt-forming agent. Specific examples of the salt forming agent include trialkylamines such as ammonia, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, and tri-n-butylamine; N-methylmorpholine, N An N-alkylmorpholine such as ethylmorpholine or an N-dialkylalkanolamine such as N-dimethylethanolamine or N-diethylethanolamine. These may be used alone or in combination of two or more.

In order to provide water solubility, in the case where a polyhydric alcohol compound having a carboxylic acid (salt) group is used as a copolymer component, the urethane is obtained by setting the total polyisocyanate component of the urethane resin to 100 mol%. The composition of the polyalcohol compound having a carboxylic acid (salt) group in the resin is preferably from 3 to 60 mol%, more preferably from 5 to 40 mol%. In the case where the composition molar ratio is less than 3 mol%, there is a case where aqueous dispersion becomes difficult. Further, when the composition molar ratio exceeds 60 mol%, the water resistance is lowered, so that the moist heat resistance may be lowered.

The glass transition point temperature of the urethane resin of the present invention is preferably less than 0 ° C, more preferably less than -5 ° C. When the glass transition point temperature is less than 0 ° C, it is preferable to easily achieve appropriate flexibility from the viewpoint of stress relaxation of the coating layer.

The urethane resin is preferably contained in an amount of 10% by mass or more and 90% by mass or less based on the crosslinking agent. In particular, in the case of a lens layer, in order to achieve high adhesion, it is more preferably 20% by mass or more and 80% by mass or less. When the content of the urethane resin is large, the adhesion under high temperature and high humidity is lowered, and conversely, when the content is small, the adhesion at the initial stage is lowered.

In order to improve the solvent resistance, the urethane resin of the present invention may be added to a urethane resin itself by adding a cross-linking group or a self-crosslinking group. Thereby, the degree of crosslinking of the resin is increased and the solvent resistance is improved. The self-crosslinking group to be used in the present invention is not particularly limited, and a relatively stable stanol group can be suitably used in the aqueous coating liquid.

The resin other than the urethane resin of the present invention may also contain those which are intended to improve adhesion. For example, a polyether or a urethane resin having a polyester as a constituent component, an acrylic resin, a polyester resin or the like can be exemplified.

(crosslinking agent)

In the present invention, it is necessary to contain a crosslinking agent in the coating layer. By containing a crosslinking agent, the adhesion under high temperature and high humidity can be further improved. In the case of the crosslinking agent, it is preferred to react with a carboxylic acid group, a hydroxyl group, an amine group or the like to form a guanamine bond, a urethane bond or a urea bond, which is difficult to deteriorate under high-temperature and high-humidity treatment. Conversely, in the case of an ester bond or an ether bond, it is not preferable to have hydrolyzability. The crosslinking agent which can be suitably used in the present invention may, for example, be a melamine-based, an isocyanate-based, a carbodiimide-based or an oxazoline-based. Among these, an isocyanate-based or carbodiimide-based system is preferable from the time stability of the coating liquid and the effect of improving the adhesion under high-temperature and high-humidity treatment. Further, it is particularly preferable to use an isocyanate crosslinking agent in order to achieve appropriate flexibility to the coating layer and to appropriately provide a stress relieving action of the coating layer. Further, in order to promote the crosslinking reaction, a catalyst or the like is suitably used as needed.

The content of the crosslinking agent is preferably 10% by mass or more and 90% by mass or less based on the urethane resin. More preferably, it is 20 mass% or more and 80 mass% or less. In less cases, the solvent resistance of the coating layer is lowered, and the adhesion under high temperature and high humidity is lowered, and in many cases, the flexibility of the resin of the coating layer is lowered, and the bonding is performed under normal temperature, high temperature and high humidity. Reduced sex.

In the present invention, in order to increase the strength of the coating film, two kinds of crosslinking agents may be mixed. Further, in order to promote the crosslinking reaction, a catalyst or the like is suitably used as needed.

(additive)

In the present invention, particles may be contained in the coating layer. The particles can be exemplified by: (1) cerium oxide, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, titanium dioxide, satin. Satin white, aluminum citrate, diatomaceous earth, calcium citrate, aluminum hydroxide, hydrated halloysite, magnesium carbonate, magnesium hydroxide and other inorganic particles; (2) acrylic or methacrylic acid , vinyl chloride, vinyl acetate, nylon, styrene/acrylic, styrene/butadiene, polystyrene/acrylic, polystyrene/isoprene, polystyrene/different Pentylene type, methyl methacrylate / butyl methacrylate type, melamine type, polycarbonate type, urea type, epoxy type, urethane type, phenol type, phthalic acid diene Organic particles such as esters and polyesters.

The particles are preferably those having an average particle diameter of from 1 to 500 nm. The average particle diameter is not particularly limited, and it is preferably from 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.

Further, the above average particle diameter is obtained by photographing a cross section of a laminated film at a magnification of 120,000 times using a transmission electron microscope (TEM), and measuring the maximum diameter of ten or more particles existing in the cross section of the coating layer, and determining the average diameter as the average value. Got it.

The content of the particles is preferably 0.5% by mass or more and 20% by mass or less. In less cases, sufficient anti-caking properties cannot be obtained. Also, it causes deterioration of scratch resistance. In many cases, not only the transparency of the coating layer is deteriorated, but also the film strength is lowered.

The coating layer may contain a surfactant in order to improve the leveling property at the time of coating and to defoam the coating liquid. The surfactant may be any of a cationic type, an anionic type, and a nonionic type, and is preferably a guanidine type, an acetylene glycol type or a fluorine type surfactant. The surfactant is preferably in a range of 0.005 to 0.5% by mass in the coating liquid, insofar as it does not impair the adhesion to the optical functional layer.

The easily adhesive polyester film of the present invention preferably has a haze value of 2.5% or less, more preferably 2.0% or less, still more preferably 1.5% or less. Further, in order to obtain high transparency, it is preferred to make the average particle size of the urethane resin small. Thereby, the dispersibility/miscibility of the resin can be improved, and high transparency can be 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, more preferably 100 nm or less.

In order to provide other functional properties of the coating layer, it is also possible to contain various additives without damaging the degree of adhesion to the sealing material. The additive may, for example, be a fluorescent dye, a fluorescent whitening agent, a plasticizer, an ultraviolet absorber, a pigment dispersant, a suds suppressor, an antifoaming agent, a preservative, an antistatic agent or the like.

In the present invention, a method of providing a coating layer on a polyester film may be a method in which a coating liquid containing a solvent, particles, or a resin is applied to a polyester film and dried. The solvent may, for example, be an organic solvent such as toluene or water or a mixture of water and a water-soluble organic solvent. From the viewpoint of environmental problems, water itself or a water-soluble organic solvent is preferably mixed with water.

(Manufacture of easy-adhesive polyester film)

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

After the PET resin was sufficiently vacuum-dried, it was supplied to an extruder, and a molten PET resin of about 280 ° C was melt-extruded into a sheet shape on a rotary cooling roll from a T-die, and cooled and solidified by an electrostatic external addition method to obtain an Stretch the PET sheet. The unstretched PET sheet may be composed of a single layer or a composite layer formed by a co-extrusion method. Further, it is preferred that the PET resin contains substantially no inert particles.

The obtained unstretched PET sheet was stretched by 2.5 to 5.0 times in the longitudinal direction by a roll heated to 80 to 120 ° C to obtain a one-axis stretched PET film. Further, the end portion of the film was held by a jig, and guided to a hot air region heated to 70 to 140 ° C, and stretched 2.5 to 5.0 times in the width direction. Next, it is guided to a heat treatment zone of 160 to 240 ° C, and heat treatment is performed for 1 to 60 seconds to complete the crystal alignment.

At any stage of the film production step, a coating liquid is applied to at least one side of the PET film to form the coating layer. The coating layer is not particularly problematic even if it is formed on both sides of the PET film. The solid content concentration of the resin composition in the coating liquid is preferably from 2 to 35% by weight, particularly preferably from 4 to 15% by weight.

Any method known in the art for applying the coating liquid to the PET film can be used. For example, a reverse roll coating method, a gravure coating method, a kiss coating method, a die coater method, a roll brush method, a spray coating method, an air knife coating method, a wire bar coating method, a tube scraper ( Pipe doctor) method, impregnation coating method, curtain coating method, and the like. These methods may be applied separately or in combination.

In the present invention, the coating layer is a PET film which is not stretched or stretched, and is applied to the PET film after being applied to the film by stretching and drying in at least one axial direction, followed by heat treatment.

In the present invention, the thickness of the finally obtained coating layer is 20 to 350 nm, and the coating amount after drying is preferably 0.02 to 0.5 g/m ² . When the coating amount of the coating layer is less than 0.02 g/m ² , the effect with respect to the adhesion is hardly any. On the one hand, when the coating amount is more than 0.5 g/m ² , the haze is increased.

The easy-adhesive polyester film roll obtained by winding the easy-adhesive polyester film of the present invention is also an appropriate aspect of the present invention. The coating layer of the present invention has good anti-caking property due to the addition of a crosslinking agent, and can be suitably used even in the case of a roll body in order to improve productivity.

The thickness of the easily-adhesive polyester film of the present invention is not particularly limited, and may be arbitrarily determined in the range of 25 to 500 μm in accordance with the specifications 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 one hand, the lower limit of the film thickness is preferably 50 μm, particularly preferably 75 μm. The film thickness is less than 25 μm, and it is easy to make the mechanical strength insufficient. On the other hand, when the film thickness exceeds 500 μm, it is difficult to wind it into a roll shape.

In the case where the easily-adhesive polyester film of the present invention is used as a roll, the roll length and width can be appropriately determined depending on the use of the film roll. The roll length of the film roll is preferably 1,500 m or more, more preferably 1800 m or more. Further, the upper limit of the roll length is preferably 5000 m. Further, the width of the film roll is preferably 500 mm or more, more preferably 800 mm. Further, the upper limit of the width of the film roll is preferably 2000 mm.

(optical film for optical use)

The optical laminated polyester film of the present invention is at least one side of the coating layer of the polyester film, and the laminated layer is selected from the group consisting of a hard coat layer, a light diffusion layer, a lens layer, an electromagnetic wave absorbing layer, a near-infrared ray shielding layer, and a transparent conductive layer. At least one layer of the optical functional layer of the layer. Further, in terms of the lens layer, any shape, for example, a dome lens, a fresnel lens, a microlens, or the like can be suitably used.

The material used for the optical functional layer is not particularly limited, and may be polymerized by drying, heat, chemical reaction or irradiation with any one of electron beam, radiation, and ultraviolet light, and/or a reactive resin compound may be used. The curable resin may, for example, be a melamine-based, acrylic-based, fluorene-based or polyvinyl alcohol-based curable resin. However, from the viewpoint of obtaining high surface hardness or optical design, photocurability is preferred. A type of acrylic curable resin. A polyfunctional (meth)acrylate type monomer or an acrylate type oligomer can be used for such an acrylic curable resin, and a polyester acrylate type is mentioned as an example of an acrylate type oligomer. And an epoxy acrylate type, a urethane acrylate type, a poly acrylate type, a polybutyl acrylate type, and a poly acrylate acrylate. A coating composition for forming the optical functional layer can be obtained by mixing a reactive diluent, a photopolymerization initiator, a sensitizer, or the like with the acrylic curable resin.

Moreover, the polyester film of the present invention can obtain good adhesion strength even in this optical use. Specifically, a photo-sensitive layer, a diazo photosensitive layer, a mat layer, a magnetic layer, an inkjet ink accepting layer, a hard coat layer, an ultraviolet curable resin, and a thermosetting resin may be exemplified. , printing ink or UV ink, adhesive for dry lamination or extrusion laminating, metal or inorganic or vacuum evaporation of such oxides, electron beam evaporation, sputtering, ion plating, CVD, A resulting thin film layer such as plasma polymerization, an organic barrier layer, or the like.

Example

Next, the present invention will be described in detail by way of examples and comparative examples, but the present invention is of course not limited to the following examples. Further, the evaluation method used in the present invention is as follows.

(1) Intrinsic viscosity

According to JIS K 7367-5, the solvent was measured at 30 ° C using a mixed solvent of phenol (60% by mass) and 1,1,2,2-tetrachloroethane (40% by mass).

(2) Glass transfer point temperature

The glass transition start temperature was determined from the DSC curve using a differential scanning calorimeter (DSC6200, manufactured by Seiko Instruments Inc.) in accordance with JlS K 7121.

(3) Determination of absorbance caused by infrared spectroscopy

With respect to the obtained easily bondable polyester film, the coating layer was chipped, and about 1 mg of the sample was taken. A sample of a coating layer (size: about 50 μm × about 50 μm) formed into a film having a thickness of about 1 μm was formed by applying pressure to the sample to be taken. In addition, the blank sample was a PET resin which was homogenous to the base film, and a sample piece (blank sample piece) was prepared in the same manner as in this procedure.

The prepared sample piece was placed on a KBr plate, and the infrared absorption spectrum was measured by a microscopic transmission method under the following conditions. The infrared spectroscopy spectrum of the coating layer was determined as the spectrum by the difference between the infrared spectroscopy spectrum obtained from the coated layer sample piece and the spectrum of the blank sample piece.

Absorbance at 1460cm ^-1 from the vicinity of the aliphatic polycarbonates of component (A _1460), the region having a 1460 ± 10cm ^-1 at the absorption maximum, is set to the high value of the absorption peak, 1530 cm from the urethane component ^- The absorbance in the vicinity of ¹ (A ₁₅₃₀ ) has an absorption maximum in the region of 1530 ± 10 cm ^-1 and is set to a value at which the absorption peak is high. In addition, the baseline is a link between the sides of the peaks of the respective maximum absorption peaks. The absorbance ratio was determined from the obtained absorbance by the following formula.

(absorbance ratio) = A ₁₄₆₀ / A ₁₅₃₀

(measurement conditions)

Device: FT-IR analysis device SPECTRA

TECH company's IRμs/SIRM

Detector: MCT

Decomposition energy: 4cm ^-1

Cumulative number: 128 times

(4) Total transmittance of easy-adhesive polyester film

The total light transmittance of the obtained easily-adhesive polyester film was measured in accordance with JIS K 7105 using a turbidimeter (manufactured by Nippon Denshoku Co., Ltd., NDH2000).

(5) Haze of easy-adhesive polyester film

The haze of the obtained easily-adhesive polyester film was measured in accordance with JlS K 7136 using a turbidimeter (manufactured by Nippon Denshoku Co., Ltd., NDH2000).

(6) Adhesiveness

A photocurable hard coat layer or a photocurable acrylic layer or a photocurable urethane/acrylic layer (hereinafter referred to as an optical functional layer) of the obtained optical polyester film for laminated use, using a cutter guide having a gap of 2 mm (cutter guide), through the optical functional layer, 100 mesh-shaped cuts to the substrate film were made. Next, a cellophane adhesive tape (No. 405, manufactured by Nichiban Co., Ltd.; 24 mm wide) was adhered to the cut surface of the lattice, wiped with an eraser, and completely adhered. Thereafter, after the operation of vertically peeling the cellophane adhesive tape from the optical functional layer of the optical laminated polyester film five times, the number of the lattices peeled off from the optical functional layer of the optical laminated polyester film was visually counted. The adhesion between the optical functional layer and the base film was determined from the following formula. Further, the partially peeled articles in the lattice were also counted in a stripped lattice, and were classified according to the following criteria.

Adhesion (%) = (1 - number of stripped strips / 100) × 100

◎: 100%, or material damage of the optical functional layer

O: 99 to 90%

△: 89 to 70%

x: 69 to 0%

(7) Heat and humidity resistance

The obtained optical laminated polyester film was placed in a high-temperature and high-humidity bath for 48 hours in an environment of 80 ° C and 95% RH. Next, the optical laminated polyester film was taken out and left to stand at room temperature for 12 hours under normal humidity. Then, in the same manner as in the above (6), the adhesion between the optical functional layer and the base film was determined, and the classification was performed based on the following criteria.

◎: 100%, or material damage of the optical functional layer

O: 99 to 90%

△: 89 to 70%

×: 69 to 0%

(Polymerization of urethane resin A-1 having an aliphatic polycarbonate polyol as a constituent component)

In a four-necked flask equipped with a stirrer, a Dimroth condenser, a nitrogen introduction tube, a cerium oxide gel drying tube, and a thermometer, 43.75 parts by mass of 4,4-diphenyl methyl diisocyanate was introduced, and 12.85 parts by mass of hydroxymethylbutanoic acid, 153.41 parts by mass of hexamethylene 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, in a nitrogen environment After stirring at 75 ° C for 3 hours, it was confirmed that the reaction liquid had reached the set amine equivalent. Next, after the reaction liquid was cooled 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 high-speed disperser (homodisper) capable of high-speed stirring, adjusted to 25 ° C, stirred and mixed at 2000 min ^-1 , and a polyurethane prepolymer solution was added and water-based. dispersion. Thereafter, 35% of the water-soluble polyurethane resin (A-1) having a solid content was prepared by removing a part of acetone and water under reduced pressure. The glass transition point temperature of the obtained polyurethane resin (A-1) was -30 °C.

(Polymerization of urethane resin A-2 having an aliphatic polycarbonate polyol as a constituent component)

In a four-necked flask equipped with a stirrer, a Daimler condenser, a nitrogen introduction tube, a cerium oxide gel drying tube, and a thermometer, 29.14 parts by mass of 4,4-diphenylmethyl isocyanate was introduced, and a dimethylol group was added. 7.57 parts by mass of butyric acid, 173.29 parts by mass of hexamethylene carbonate diol having a number average molecular weight of 3000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent, in a nitrogen atmosphere at 75 The mixture was stirred at ° C for 3 hours, and it was confirmed that the amine equivalent of the reaction liquid was reached. Next, the reaction liquid was cooled to 40 ° C, and then 5.17 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 high-speed disperser capable of high-speed stirring, and the mixture was adjusted to 25° C., and the mixture was stirred and mixed at 2000 min ⁻¹ to add a polyurethane prepolymer solution and to be aqueousally dispersed. Thereafter, 35% of the water-soluble polyurethane resin (A-2) having a solid content of 35% was prepared by removing a part of acetone and water under reduced pressure.

(Polymerization of urethane resin A-3 having an aliphatic polycarbonate polyol as a constituent component)

In a four-necked flask equipped with a stirrer, a Daimler condenser, a nitrogen introduction tube, a cerium oxide gel drying tube, and a thermometer, 43.75 parts by mass of 4,4-diphenylmethyl isocyanate and a dimethylol group were charged. 11.12 parts by mass of butyric acid, 1.97 parts by mass of hexanediol, 143.40 parts by mass of hexamethylene 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. The mixture was stirred at 75 ° C for 3 hours under a nitrogen atmosphere, and it was confirmed that the amine equivalent of the reaction liquid was reached. Next, the reaction liquid was cooled to 40 ° C, and then 8.77 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a high-speed disperser capable of high-speed stirring, and the mixture was adjusted to 25° C., and stirred and mixed at 2000 min ⁻¹ to add a polyurethane prepolymer solution and preliminarily dispersed. . Thereafter, 35% of the water-soluble polyurethane resin (A-3) having a solid content was prepared by removing a part of acetone and water under reduced pressure.

(Polymerization of a stanol-containing urethane resin A-4 having an aliphatic polycarbonate polyol as a constituent component)

In a four-necked flask equipped with a stirrer, a Daimler condenser, a nitrogen introduction tube, a cerium oxide gel drying tube, and a thermometer, 38.41 parts by mass of isophorone diisocyanate and 6.95 mass of dimethylolpropionic acid were introduced. 158.99 parts by mass of hexamethylene 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, and stirred at 75 ° C under a nitrogen atmosphere. Hour, and confirm that the amine equivalent of the reaction solution is reached. Next, the reaction liquid was cooled to 40 ° C, and then 4.37 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Then, 3.84 parts by mass of γ-(aminoethyl)aminopropyltriethoxydecane, 1.80 parts by mass of 2-[(2-aminoethyl)amino]ethanol, and 450 g of water were added, and the polyurethane prepreg was added. The polymer solution is dispersed in an aqueous solution. Thereafter, 30% of the water-soluble stanol-containing polyurethane resin (A-4) having a solid content of 30% was prepared by removing a part of acetone and water under reduced pressure.

(Polymerization of urethane resin A-5 having an aliphatic polycarbonate polyol as a constituent component)

In addition to changing the number of polyhexamethylene diols of the water-soluble polyurethane resin (A-1) having a number average molecular weight of 2000 to hexamethylene methacrylate diol having a number average molecular weight of 1,000, In the same manner, a water-soluble polyurethane resin (A-5) having a solid content of 35% was obtained.

(Polymerization of urethane resin A-6 having an aliphatic polycarbonate polyol as a constituent component)

In addition to changing the number average molecular weight of 2000 of the water-soluble polyurethane resin (A-1) to hexamethylene carbonate diol having a number average molecular weight of 5,000, the others are In the same manner, a water-soluble polyurethane resin (A-6) having a solid content of 35% was obtained.

(Polymerization A-7 of a urethane resin having a polyester polyol as a constituent component)

In the same manner as in the case of changing the number average molecular weight of 2000 of the water-soluble polyurethane resin (A-1) to a polyester diol having a number average molecular weight of 2,000, A water-soluble polyurethane resin (A-7) having a solid content of 35% was obtained.

(Polymerization A-8 of a urethane resin having a polyether polyol as a constituent component)

The same method is used except that the polymethyl urethane diol having a number average molecular weight of 2000 of the water-soluble polyurethane resin (A-1) is changed to a polyether diol having a number average molecular weight of 2000. A water-soluble polyurethane resin (A-8) having a solid content of 35% was obtained.

(polymerization of block polyisocyanate crosslinker)

In a flask equipped with a stirrer, a thermometer, and a reflux cooling tube, 100 parts by mass of a polyisocyanate compound (Duranate TPA, manufactured by Asahi Kasei Chemicals Co., Ltd.) having an isomeric isocyanate structure containing hexamethylene dihydrogenate as a raw material was charged. 55 parts by mass of propylene glycol monomethyl ether acetate and 30 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 750) were kept at 70 ° C for 4 hours under a nitrogen atmosphere. Thereafter, the temperature of the reaction liquid was lowered to 50 ° C, and 47 parts by mass of methyl ethyl ketone oxime was dropped. The infrared spectrum of the reaction liquid was measured, and it was confirmed that the absorption of the isocyanate group disappeared, and a block polyisocyanate aqueous dispersion (B) having a solid content of 75% by mass was obtained.

(polymerization of oxazoline crosslinking agent)

In a flask equipped with a thermometer, a nitrogen gas introduction tube, a reflux condenser, a dropping funnel, and a stirrer, a mixture of 58 parts by mass of ion-exchanged water as an aqueous medium and 58 parts by mass of isopropyl alcohol; and a polymerization initiator (2, 2) were charged; '-Azobis(2-methylpropanepropane) dihydrochloride) 4 parts by mass. On the other hand, in the dropping funnel, 16 parts by mass of 2-isopropenyl-2-oxazoline as a polymerizable unsaturated monovalent body having an oxazoline group, and methoxypolyethylene glycol acrylate (Ethylene diacetate) A mixture of 32 parts by mass of alcohol and a mass of 32 parts by mass of methyl methacrylate was added to the mixture at a temperature of 70 ° C for 1 hour under a nitrogen atmosphere. After the completion of the dropwise addition, the reaction solution was stirred for 9 hours, and then cooled to obtain a water-soluble resin (C) having an oxazoline group having a solid concentration of 40% by mass.

(polymerization of a carbon diimine crosslinking agent)

In a flask equipped with a stirrer, a thermometer, and a reflux cooling tube, 168 parts by mass of hexamethylene diisocyanate and 220 parts by mass of polyethylene glycol monomethyl ether (M400, average molecular weight: 400) were placed, and stirred at 120 ° C for 1 hour. Further adding 26 parts by mass of dicyclohexylmethyl 4,4'-diisocyanate and 3-methyl-1-phenyl-2-phosphene-1 as a carbon dithilylation catalyst - 3.8 parts by mass of an oxide (2% by weight based on total isocyanate), and further stirred at 185 ° C for 5 hours under a nitrogen stream. The infrared spectrum of the reaction liquid was measured, and it was confirmed that the absorption at a wavelength of 2200 to 2300 cm ^-1 had disappeared. The mixture was cooled to 60 ° C, and 567 parts by mass of ion-exchanged water was added to obtain a carbodiimide water-soluble resin (D) having a solid content of 40% by mass.

Example 1 (1) Adjustment of coating liquid

The coating agent described below was mixed to prepare a coating liquid.

(cerium oxide sol having an average particle diameter of 40 nm, solid content concentration of 40% by mass)

Particles 0.07 mass%

(cerium oxide sol having an average particle diameter of 450 nm, solid content concentration of 40% by mass)

Surfactant 0.05% by mass

(矽, solid content concentration 100% by mass)

(2) Manufacture of easy-adhesive polyester film

The film raw material polymer was dried at 135 ° C for 6 hours under a reduced pressure of 133 Pa at a PET resin particle having an intrinsic viscosity of 0.62 dl/g and substantially containing no particles. Thereafter, the mixture was supplied to an extruder, melt-extruded into a sheet shape at about 280 ° C, and subjected to rapid cooling and adhesion curing on a rotary 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 by a roll group having a peripheral rate difference to obtain a one-axis stretched PET film.

Next, this coating liquid was applied to one surface of the PET film by a roll coating method, and then dried at 80 ° C for 20 seconds. Further, it was adjusted so that the final coating amount after drying (after biaxial stretching) was 0.15 g/m ² . Subsequently, the film was stretched 4.0 times in the width direction at 120 ° C with a stretcher, and heated at 230 ° C for 0.5 second while the length of the film in the width direction was fixed. Further, at 230 ° C for 10 seconds, 3%. Relaxation processing in the width direction. The both ends were trimmed, wound by a winding device, and further divided into two in the width direction, and slits were obtained to obtain a film roll having a width of 1300 mm, a film length of 3000 m, and a film thickness of 100 μm. The evaluation results of the obtained easily bondable polyester film are shown in Table 1.

(3) Manufacture of laminated polyester film for optics

(Optical laminated polyester film with hard coating layer)

On the coating layer of the above-mentioned easy-adhesive polyester film, the coating layer (E) of the coating composition for forming a hard coat layer having the following composition was dried at 70 ° C for 1 minute using a #10 wire rod, and the solvent was removed. Next, a film coated with a hard coat layer was irradiated with ultraviolet rays of 300 mJ/cm ² 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 coating layer forming coating liquid (E)

Methyl ethyl ketone 65.00% by mass

Dipentaerythritol hexaacrylate 27.20% by mass

(New Nakamura Chemical A-DPH)

Polyethylene diacrylate 6.80% by mass

(Xinzhongcun Chemical System A-400)

Photopolymerization initiator 1.00% by mass

(Irgacure 184, manufactured by Ciba Specialty Chemicals)

(Optical laminated polyester film with photocurable urethane/acrylic layer)

On the SUS plate (SUS304) having a thickness of 1 mm, which is kept clean, about 5 g of the photocurable acrylic coating liquid described below is carried, and the coating layer of the film sample is brought into contact with the photocurable acrylic coating liquid to be wide. A manual load rubber roller of 10 cm and a diameter of 4 cm was pressed from the film sample to draw the photocurable urethane/acrylic coating liquid (F). Next, ultraviolet light of 500 mJ/cm ^{2 was} irradiated from the film surface side using a high pressure mercury lamp to harden the photocurable urethane/acrylic resin. A film sample having a photocurable urethane/acrylic layer having a thickness of 20 μm was peeled off from the SUS plate to obtain an optical laminated polyester film.

Photocurable urethane/acrylic coating liquid (F)

Photocurable acrylic resin 67.00% by mass

(New Nakamura Chemical A-BPE-4)

Photocurable acrylic resin 15.00% by mass

(New Nakamura Chemical AMP-10G)

Photocurable urethane/acrylic resin 15.00% by mass

(New Nakamura Chemical System U-6HA)

Photopolymerization initiator 3.00% by mass

(Irgacure 184, manufactured by Ciba Specialty Chemicals)

(Optical laminated polyester film having a photocurable acrylic layer)

The photocurable urethane/acrylic coating liquid (F) of the optical laminated polyester film having a photocurable urethane/acrylic layer is changed to a photocurable acrylic coating liquid (G). Other than the above, a laminated polyester film for optics was obtained in the same manner.

Photocuring acrylic coating liquid (G)

Photocurable acrylic resin 67.00% by mass

(New Nakamura Chemical A-BPE-4)

Photocurable acrylic resin 30.00% by mass

(New Nakamura Chemical AMP-10G)

Photopolymerization initiator 3.00% by mass

(Irgacure 184, manufactured by Ciba Specialty Chemicals)

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 polyurethane resin was changed to the polyurethane resin (A-5).

Comparative example 2

In the same manner as in Example 1, except that the polyurethane resin was changed to the polyurethane resin (A-6), an easy-adhesive polyester film and an optical laminated polyester film were obtained.

Comparative example 3

An easy-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-7).

Comparative 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 polyurethane resin was changed to the polyurethane resin (A-8).

Comparative Example 5

In the same manner as in Example 1, except that the coating liquid was changed to the following, an easy-adhesive polyester film and an optical laminated polyester film were obtained.

Water 53.04% by mass

Isopropyl alcohol 30.00% by mass

Polyurethane resin (A-1) 16.13% by mass

Particles 0.71% by mass

(cerium oxide sol having an average particle diameter of 40 nm, solid content concentration of 40% by mass)

Particles 0.07 mass%

(cerium oxide sol having an average particle diameter of 450 nm, solid content concentration of 40% by mass)

Surfactant 0.05% by mass

(矽, solid content concentration 100% by mass)

Example 2

In the same manner as in Example 1, except that the coating liquid was changed to the following, an easy-adhesive polyester film and an optical laminated polyester film were obtained.

Water 53.91% by mass

Isopropyl alcohol 30.00% by mass

Polyurethane resin (A-1) 14.51% by mass

Block polyisocyanate aqueous dispersion (B) 0.75 mass%

Particles 0.71% by mass

(cerium oxide sol having an average particle diameter of 40 nm, solid content concentration of 40% by mass)

Particles 0.07 mass%

(cerium oxide sol having an average particle diameter of 450 nm, solid content concentration of 40% by mass)

Surfactant 0.05% by mass

(矽, solid content concentration 100% by mass)

Example 3

In the same manner as in Example 1, except that the coating liquid was changed to the following, an easy-adhesive polyester film and an optical laminated polyester film were obtained.

Water 54.76 mass%

Isopropyl alcohol 30.00% by mass

Polyurethane resin (A-1) 12.90% by mass

Block polyisocyanate aqueous dispersion (B) 1.51% by mass

Particles 0.71% by mass

(cerium oxide sol having an average particle diameter of 40 nm, solid content concentration of 40% by mass)

Particles 0.07 mass%

(cerium oxide sol having an average particle diameter of 450 nm, solid content concentration of 40% by mass)

Surfactant 0.05% by mass

(矽, solid content concentration 100% by mass)

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 liquid was changed to the following.

Water 57.35 mass%

Isopropyl alcohol 30.00% by mass

Polyurethane resin (A-1) 8.06% by mass

Block polyisocyanate aqueous dispersion (B) 3.76 mass%

Particles 0.71% by mass

(cerium oxide sol having an average particle diameter of 40 nm, solid content concentration of 40% by mass)

Particles 0.07 mass%

(cerium oxide sol having an average particle diameter of 450 nm, solid content concentration of 40% by mass)

Surfactant 0.05% by mass

(矽, solid content concentration 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 liquid was changed to the following.

Water 59.92% by mass

Isopropyl alcohol 30.00% by mass

Polyurethane resin (A-1) 3.23% by mass

Block polyisocyanate aqueous dispersion (B) 6.02% by mass

Particles 0.71% by mass

(cerium oxide sol having an average particle diameter of 40 nm, solid content concentration of 40% by mass)

Particles 0.07 mass%

(cerium oxide sol having an average particle diameter of 450 nm, solid content concentration of 40% by mass)

Surfactant 0.05% by mass

(矽, solid content concentration 100% by mass)

Example 6

In the same manner as in Example 1, except that the coating liquid was changed to the following, an easy-adhesive polyester film and an optical laminated polyester film were obtained.

Water 60.79 mass%

Isopropyl alcohol 30.00% by mass

Polyurethane resin (A-1) 1.61% by mass

Block polyisocyanate aqueous dispersion (B) 6.77 mass%

Particles 0.71% by mass

(cerium oxide sol having an average particle diameter of 40 nm, solid content concentration of 40% by mass)

Particles 0.07 mass%

(cerium oxide sol having an average particle diameter of 450 nm, solid content concentration of 40% by mass)

Surfactant 0.05% by mass

(矽, solid content concentration 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 polyurethane resin was changed to the polyurethane resin (A-2).

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 polyurethane resin was changed to the polyurethane resin (A-3).

Example 9

An easy-adhesive polyester film and an optical laminated polyester were obtained in the same manner as in Example 1 except that the polyurethane resin was changed to the stanol-containing polyurethane resin (A-4). film.

Example 10

An optical laminated polyester film was obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion (B) was changed to the oxazoline group-containing water-soluble resin (C).

Example 11

An optical laminate polyester film was obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion (C) was changed to the carbodiimide water-soluble resin (D).

Example 12

An optical laminate polyester film was obtained in the same manner as in Example 1 except that the block polyisocyanate aqueous dispersion (C) was an imidomethylolmelamine (solid content concentration: 70% by mass).

Example 13

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 liquid was changed to the following.

Water 62.82% by mass

Isopropyl alcohol 30.00% by mass

Polyurethane resin (A-1) 5.64% by mass

Block polyisocyanate aqueous dispersion (B) 1.13% by mass

Particle 0.35 mass%

(cerium oxide sol having an average particle diameter of 40 nm, solid content concentration of 40% by mass)

Particle 0.04% by mass

(cerium oxide sol having an average particle diameter of 450 nm, solid content concentration of 40% by mass)

Surfactant 0.02% by mass

(矽, solid content concentration 100% by mass)

Industrial availability

The easy-adhesive polyester film of the present invention is excellent in adhesion to an optical functional layer and excellent in adhesion under high temperature and high humidity (moisture heat resistance), and thus is particularly suitable for optical use, and is mainly used as a hard coat for a display or the like. A base film of an optical functional film such as a film and an antireflection film, a light diffusion sheet, a lens sheet, a near-infrared ray blocking film, a transparent conductive film, or an anti-glare film using the film is extremely suitable.

Claims (6)

An easy-adhesive polyester film characterized by a polyester film having a coating layer on at least one side thereof, the coating layer being a urethane resin in which an aliphatic polycarbonate polyol and a polyisocyanate are constituent components And a crosslinking agent as a main component, the urethane resin, wherein the constituent component contains 3 to 60 mol% of a polyol having a carboxylic acid group or a carboxylate group in the wholly polyisocyanate. In the infrared spectroscopic spectrum of the coating layer, the ratio of the absorbance (A ₁₄₆₀ ) in the vicinity of ₁₄₆₀ cm ^-1 from the aliphatic polycarbonate component to the absorbance (A ₁₅₃₀ ) in the vicinity of ₁₅₃₀ cm ^-1 from the urethane component ( A ₁₄₆₀ /A ₁₅₃₀ ) is 0.40-1.55. The easy-adhesive polyester film of claim 1, wherein the crosslinking agent is selected from the group consisting of a melamine crosslinking agent, an isocyanate crosslinking agent, a carbodiimide crosslinking agent, and an oxazoline crosslinking agent. At least one crosslinking agent in the crosslinking agent. The easy-adhesive polyester film of the first aspect of the invention, wherein the ratio of the urethane resin and the crosslinking agent which constitutes the aliphatic polycarbonate polyalcohol in the coating layer is a mass ratio (amino group) The formate resin/crosslinking agent) is from 1/9 to 9/1. The easy-adhesive polyester film of claim 1, wherein the polyester film has a haze of 2.5% or less. A laminated polyester film which is in the range of items 1 to 4 as claimed in the patent application The coating layer of the easy-adhesive polyester film of any one of the layers is selected from at least one of a hard coat layer, a light diffusion layer, a lens layer, an electromagnetic wave absorbing layer, a near-infrared ray blocking layer, and a transparent conductive layer. Made of optical functional layers. An optically easy-adhesive polyester film roll which is obtained by winding an easy-adhesive polyester film according to any one of claims 1 to 4.