JP2001302994A - Easily adhesive film for optical use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily adhesive film for optical use comprising a substrate film containing a regenerated resin as a film material, having excellent transparency, adhesiveness of ease, and suitable tone of color for optical use. SOLUTION: This easily adhesive film for optical use has a polymer easily adhesive layer (B) formed on at least one surface of a biaxial orientation polyester film (A), as a substrate material, and the biaxial orientation polyester film (A) contains, as its material, a regenerated resin generated from a biaxial orientation polyester film (a) with a polymer easily adhesive layer (b) formed on at least one surface, and color b* value of the easily adhesive film for optical use is not higher than 7.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical adhesive film. Specifically, as a film material of the base film, it is an optically easy-to-adhesive film containing a recycled resin obtained from the same kind of film, and has excellent transparency,
The present invention relates to an optically easy-to-adhesive film having an easy-to-adhesive property and having an optically favorable color tone.

[0002]

2. Description of the Related Art Biaxially oriented polyester films are widely used as various optical films because of their excellent transparency, dimensional stability and chemical resistance. In particular, the use of a base film for a prism lens sheet, a base film for a touch panel, a base film for a backlight, a base film for an AR (anti-reflection) film, and a shatterproof film for a CRT used in a liquid crystal display device is excellent. Since strength and dimensional stability are required, 5
A relatively thick film of 0 μm or more is preferably used.

[0003] Such optical films are required to have excellent transparency and excellent easy adhesion to prism lens processing, hard coating processing, and AR processing. In general, biaxially oriented polyester films are generally made of other materials, For example, it is known that adhesion to a prism lens or a hard coat mainly containing an acrylic resin is poor. For this reason, various types of optically easy-to-adhesive films in which an easily-adhesive layer made of a polyurethane resin or the like is formed on the surface of a biaxially oriented polyester film have been proposed for the use (for example, JP-A-6-340049). ).

[0004] Conventionally, a biaxially oriented polyester film is usually used from the viewpoint of economical efficiency by using a recycled resin obtained by recycling a waste resin generated in a film forming step or the like. There is also a demand for the use of recycled resin for optically-adhesive films having an oriented polyester film as a base material.

However, since the optically easy-to-adhesive film based on the biaxially oriented polyester film contains a polyurethane resin as a component of the easily-adhesive layer, when this is used as a recycled resin, the film is colored yellow and the product becomes yellow. There was a problem of degrading the quality.

[0006]

Accordingly, the present invention uses a base film containing a recycled resin as a film material, has excellent transparency and easy adhesion, and has an optically favorable color tone. An object of the present invention is to provide an easy-to-use optical adhesive film having:

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the above-mentioned object can be achieved by the optically easy-to-use adhesive film shown below, and completed the present invention. I came to.

That is, the present invention relates to an optically easy-to-adhesive film comprising a biaxially oriented polyester film (A) as a base material and a polymer easy-to-adhesive layer (B) formed on at least one surface of the base material. Axial oriented polyester film (A)
Contains, as a material thereof, a recycled resin produced from a biaxially oriented polyester film (a) having at least one surface with a high-polymer easy-adhesion layer (b), and a color b * of an easily-adhesive film for optical use. A film having a value of 7.0 or less.

[0009] The optically-adhesive film using a recycled resin as the film material of the biaxially oriented polyester film (A) as the base material is useful from the viewpoint of economy and resource saving.
Those having a color b * value of 7.0 or less have low coloring and satisfy a practical color tone. The color b * value is preferably 6.0 or less, more preferably 5.0 or less.

[0010] The color b * value is a value measured by stacking ten optically easy-to-adhesive films using a colorimeter (ZE2000) manufactured by Nippon Denshoku Industries Co., Ltd. The thickness of the optically easy-to-use adhesive film varies depending on the application and is determined according to the application.

In the above-mentioned optically-adhesive film of the present invention, the content of the recycled resin in the biaxially oriented polyester film (A) serving as the film base is preferably 40% by weight or less.

In order to make the value of the color b * value of the easily adhesive film for optical use 7.0 or less, the content of the recycled resin in the biaxially oriented polyester film (A) serving as the base material of the film is 40% by weight. % Or less is effective. Further, it is effective to set the content to 15% by weight or less. On the other hand, considering only economic efficiency, it is preferable that the content of the recycled resin is large.

The content of the recycled resin indicates a case where the recycled resin is continuously used at the ratio. The color b * value does not increase even if the ratio is used more than once. When using regenerated resin only once,
When used continuously, it is estimated as follows. In other words, if the ratio of the regenerated resin used spontaneously is α,
The non-recovery is 1-α, and in the first pass, the non-recovery (1-
α) is one pass, and collection (α) is two passes. Therefore, the average number of passes is 1 + α, which is the sum of (1−α) and (α) × 2. On the other hand, when used continuously, 1 /
It becomes the same as that used in the ratio of (1-α), and the degree of coloring becomes more intense.

In the above-mentioned optically-adhesive film of the present invention, the film material of the biaxially oriented polyester film (A) serving as the base material is decompressed in the absence of oxygen.
It is preferably prepared by drying.

In order not to increase the color b * value of the easily adhesive film for optical use, it is necessary to suppress the oxidation of the polyester which is the film material of the biaxially oriented polyester film (A) from the polymerization stage. In particular, the materials (including the reclaimed resin) used for the biaxially oriented polyester film (A) are preferably subjected to oxygen-free conditions before molding, when they are decompressed and dried, so that the materials are not exposed to oxygen. Good. In particular, it is important at a temperature of 100 ° C. or higher.

In the above-mentioned optical adhesive film of the present invention, it is preferable that the regenerated resin is melted and regenerated in the absence of oxygen.

[0017] The regenerated resin is melted and regenerated to prevent oxidation by containing no oxygen.

Further, in the optical adhesive film of the present invention, the polymer adhesive layer (b) contained in the recycled resin
Preferably contains a copolymerized polyester resin and a polyurethane resin.

When the material used for the biaxially oriented polyester film (A), which is the base material of the optically-adhesive film, contains a copolymer polyester resin in addition to the polyurethane resin, the color b * It is preferable for realizing the value.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the optically easy-to-adhesive film of the present invention will be described below.

The biaxially oriented polyester film (A) of the present invention comprises a regenerated resin (m) obtained by regenerating a biaxially oriented polyester film (a) having an easily polymerizable adhesive layer (b) formed thereon, and a reclaimed resin (m). Polyester other than m) (so-called virgin resin) is used as the film material. In addition,
The film material (regenerated resin and virgin resin) of the biaxially oriented polyester film (A) includes, in addition to the recycled resin (m), a biaxially oriented polyester film (a) having no easy-adhesion layer (b) formed thereon. Reclaimed resin (n)
Can be contained in a range where the color b * value of the optically-adhesive film is 7.0 or less.

As the material of the biaxially oriented polyester film (a) of the regenerated resin and the virgin resin, various polyester resins can be used, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, or a mixture of these. A copolymer containing a resin component as a main component is used. Among these, polyethylene terephthalate is particularly preferred.

When a polyester copolymer is used as the polyester resin, the dicarboxylic acid component serving as a copolymer component may be an aliphatic dicarboxylic acid such as adipic acid or sebacic acid, terephthalic acid, isophthalic acid, phthalic acid, or the like.
And aromatic dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid and the like, and polyfunctional carboxylic acids such as trimellilotic acid and pyromellilotic acid. Examples of the glycol component serving as a copolymer component include fatty acid glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol, propylene glycol and neopentyl glycol; aromatic glycols such as p-xylene glycol; An alicyclic glycol such as methanol; polyethylene glycol having an average molecular weight of 150 to 20,000 is used. The preferred proportion of the copolymer component in the copolymer is less than 20 mol%. 20 mol%
Above, the film strength, transparency and heat resistance may be poor.

Further, the polyester resin may contain various additives. Examples of the additive include an antistatic agent, a UV absorber, and a stabilizer.
In addition, it is preferable that particles for the purpose of imparting lubricity are not added to the biaxially oriented polyester film (A) of the present invention.

As described above, the film material of the biaxially oriented polyester film (A) of the present invention comprises a recycled resin and a virgin resin, and the virgin resin preferably has a color b * value of 4.0 or less. More preferably 3.0
Use the following: More preferably, it is 1.5 or less. A virgin resin having a color b * value or less is effective in reducing the color b * value of the biaxially oriented polyester film (A) to 7.0 or less.

On the other hand, a method for regenerating a regenerated resin includes a method in which a crushed biaxially oriented polyester film (a) containing an easily adhesive layer (b) is melted in an extruder, extruded from a nozzle, and pelletized again. A method of compressing a biaxially oriented polyester film (a) containing an easy-adhesion layer (b) pulverized at 80 to 150 ° C. to partially melt the surface to form a pellet, at a temperature of 240 to 270 ° C. It is carried out by a method of melting the whole into a solid state or the like. However, if such a regeneration treatment is carried out in the presence of oxygen such as air, the oxidation reaction may proceed and the coloring of the recycled resin may be promoted. Therefore, the regeneration treatment of the regeneration resin is performed in a state that does not contain oxygen, for example, by performing the regeneration treatment system under reduced pressure or by replacing the system with nitrogen or the like. It is better to use

The increase in the color b * value of the recycled resin as compared to the virgin resin of the same material is due to the thickness of the film (A),
The color of the reclaimed resin (m) of the biaxially oriented polyester film (a) on which the easy-adhesion layer (b) is formed as in the present invention, although it differs depending on whether the easy-adhesion layer (b) is single-sided or double-sided. The b * value generally increases by about Δ1.7 to Δ2.6 as compared with a virgin resin of the same material. On the other hand, the color b * value of the reclaimed resin (n) of the biaxially oriented polyester film (a) in which the easy-adhesion layer (b) is not formed increases by about Δ1.6 as compared with the virgin resin of the same material.

The content of the regenerated resin contained in the film material (regenerated resin and virgin resin) constituting the biaxially oriented polyester film (A) is determined by the fact that the color b * value of the obtained optically easy-to-adhere film is 7. It is adjusted to be 0 or less.

Color b of the easily adhesive film for optical use of the present invention
* The value largely depends on the ratio of the easily adhesive layer (b) contained in the biaxially oriented polyester film (A). That is, the higher the proportion of the easy-adhesion layer (b), the greater the degree of coloring when recycled. For example, when a reclaimed resin having a Δb * value (increase) of 2.6 compared to a virgin resin (color b * value: 2.8) of the same material is used, it is included in the biaxially oriented polyester film (A). If the proportion of the recycled resin exceeds 40% by weight, the color b * value exceeds 7.0, which is not preferable.

Therefore, the content of the recycled resin constituting the biaxially oriented polyester film (A) is determined by dividing the thickness of the biaxially oriented polyester film (A) according to the use of the optically easy-to-use adhesive film. In advance, (A)
The color b * value can be adjusted by appropriately determining the content of the recycled resin in consideration of the mixing ratio of the easily adhesive layer (b) contained therein.

In addition, regardless of the thickness of the biaxially oriented polyester film (A), a biaxially oriented polyester film (A) in which various kinds of recycled resins are mixed is prepared in advance, The concentration of the easily adhesive layer (b) contained in the biaxially oriented polyester film (A) estimated from the average mixing ratio is determined in advance, and the color b * of the biaxially oriented polyester film (A) is determined by the content of the regenerated resin. The intrinsic viscosity of the film material forming the biaxially oriented polyester film (A), which can be used to predict the increase in the value and determine the amount of the recycled resin used, is 0.45.
The range of -0.70 dl / g is preferable. Intrinsic viscosity is 0.
If it is less than 45 dl / g, the effect of improving the tear resistance deteriorates. On the other hand, if the intrinsic viscosity exceeds 0.70 dl / g, the increase in filtration pressure becomes large, and high-precision filtration becomes difficult.

As described above, the film materials (including the recycled resin) used for the biaxially oriented polyester film (A) are subjected to decompression and drying at a temperature of 100 ° C. or higher before molding. It is preferable to carry out the reaction in the absence of oxygen so as not to be exposed to water.

The adhesive layer (B) of the optical adhesive film of the present invention is laminated on at least one surface of the biaxially oriented polyester film (A). Such an easily adhesive layer (B)
Preferably, the polyester film is laminated by an in-line coating method in which an easy-adhesion layer is provided on at least one surface of the unstretched or uniaxially stretched polyester film, and then stretched and heat-set in at least one axial direction. In addition, if the easy-adhesion layer (B) laminated by the in-line coating method is provided with a slipperiness by containing fine particles having an appropriate particle size, a good winding property and a function of preventing scratching can be imparted. Can be. For this reason, it is not necessary to contain fine particles in the biaxially oriented polyester film (A), and high transparency can be maintained.

The material constituting the easily adhesive layer (B) of the easily adhesive optical film of the present invention is not particularly limited, and various materials such as a polyester resin, a polyurethane resin, and an acrylic resin can be used. However, it is preferable to contain a copolymerized polyester resin (X) and a polyurethane resin (Y) as main resin components. When the copolymerized polyester resin (X) alone is used, the adhesion to the polyester base film is sufficient, but the adhesion to the acrylic resin used for the prism lens or the hard coat is poor. Further, the polyurethane resin (Y) alone has excellent adhesiveness with an acrylic resin, but is inferior in adhesiveness with a polyester base film. In addition, the resin component used to form the polymer easy-adhesion layer (b) formed on at least one surface of the biaxially oriented polyester film (a) used in the recycled resin is the same as that used in the easy-adhesion layer (B). Can be

The copolymerized polyester resin (X) is
It is preferable to use a dicarboxylic acid component and a branched glycol component as constituent components. The branched glycol component is, for example, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2-methyl-2-butyl-1,3. -Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3
-Propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-
Propanediol, 2-ethyl-2-n-hexyl-
1,3-propanediol, 2,2-di-n-butyl-
1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol, and 2,2-di-n
-Hexyl-1,3-propanediol and the like.

The above-mentioned branched glycol component is contained in all the glycol components preferably in a proportion of 10 mol% or more, more preferably in a proportion of 20 mol% or more. As the glycol component other than the above compounds, ethylene glycol is most preferable. If it is a small amount, diethylene glycol, propylene glycol, butanediol,
Hexanediol or 1,4-cyclohexanedimethanol may be used.

As the dicarboxylic acid component contained as a constituent component in the copolymerized polyester resin (X), terephthalic acid and isophthalic acid are most preferred. If the amount is small, another dicarboxylic acid, in particular, an aromatic dicarboxylic acid such as diphenylcarboxylic acid and 2,6-naltalenedicarboxylic acid may be added and copolymerized. In addition to the dicarboxylic acid component, it is preferable to use 5-sulfoisophthalic acid in the range of 1 to 10 mol% in order to impart water dispersibility. For example, sulfoterephthalic acid, 5-sulfoisophthalic acid, Sulfonaphthalene isophthalic acid-2,7-
Examples thereof include dicarboxylic acid and 5- (4-sulfophenoxy) isophthalic acid and salts thereof.

The polyurethane resin (Y) is, for example, a resin containing a blocked isocyanate group, and is a heat-reactive water-soluble urethane in which the terminal isocyanate group is blocked with a hydrophilic group (hereinafter referred to as a block). No. Examples of the isocyanate group blocking agent include bisulfites and phenols containing sulfonic acid groups,
Alcohols, lactams, oximes, active methylene compounds, and the like. The blocked isocyanate group renders the urethane prepolymer hydrophilic or water-soluble. During the drying or heat setting process during film production,
When thermal energy is applied to the resin, the blocking agent deviates from the isocyanate group, so that the resin immobilizes the water-dispersible copolymerized polyester resin mixed with the self-crosslinked knitted stitch, and the terminal groups of the resin and the like. react. The resin being adjusted for the coating liquid is poor in water resistance because it is hydrophilic, but when the coating, drying and heat setting and the thermal reaction are completed, the hydrophilic group of the urethane resin, that is, the blocking agent, comes off, so that the water resistance is good. A coating is obtained.

The chemical composition of the urethane prepolymer used in the polyurethane resin (Y) is as follows:
(I) a polyol having two or more active hydrogen atoms in a molecule or a compound having at least two active hydrogen atoms in a molecule and having a molecular weight of 200 to 20,000, (i)
i) an organic polyisocyanate having two or more isocyanate groups in the molecule and, if necessary, (iii) a terminal isocyanate group obtained by reacting a chain extender having at least two active hydrogen atoms in the molecule. Is a compound having

The compound (i) is generally known to contain two or more hydroxyl groups, carboxyl groups, amino groups or mercapto groups at the terminal or in the molecule. Particularly preferred compounds are Examples include polyether polyols and polyether ester polyols.

As the polyether polyol, for example, alkylene oxides such as ethylene oxide and propylene oxide, or compounds obtained by polymerizing styrene oxide and epichlorohydrin or the like, or those obtained by random polymerization, block polymerization or addition polymerization to polyhydric alcohols are used. And the compounds obtained by the above method.

The polyester polyol and the polyether ester polyol include mainly linear or branched compounds. Succinic acid, adipic acid,
Polyvalent saturated or unsaturated carboxylic acids such as phthalic acid and maleic anhydride, or the carboxylic anhydrides and the like, ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol and It can be obtained by condensing polyhydric saturated and unsaturated alcohols such as trimethylolpropane, polyalkylene ether glycols such as relatively low molecular weight polyethylene glycol and polypropylene glycol, or a mixture of these alcohols. .

Further, as polyester polyols, polyesters obtained from lactone and hydroxy acid, and as polyether ester polyols,
Polyetheresters obtained by adding ethylene oxide or propylene oxide to polyesters produced in advance can also be used.

As the organic polyisocyanate (ii), isomers of toluylene diisocyanate, 4,4
Aromatic diisocyanates such as diphenylmethane diisocyanate, aromatic aliphatic diisocyanates such as xylylene diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate and 4,4-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and 2,2,4 -Aliphatic diisocyanates such as trimethylhexamethylene diisocyanate, or polyisocyanates in which one or more of these compounds are previously added to trimethylolpropane or the like.

The chain extender having at least two active hydrogens of the above (iii) includes ethylene glycol, diethylene glycol, 1,4-butanediol,
Glycols such as 6-hexanediol, glycerin,
Trimethylolpropane, and polyhydric alcohols such as pentaerythritol, ethylenediamine, hexamethylenediamine, diamines such as piperazine, amino alcohols such as monoethanolamine and diethanolamine, thiodiglycols such as thiodiethylene glycol, or Water. In order to synthesize a urethane polymer using the above (iii), usually, a single-stage or multi-stage isocyanate polyaddition method using the above-mentioned chain extender is used at 150 ° C or lower, preferably 70 to 120 ° C.
The reaction is carried out at a temperature of 5 ° C. for 5 minutes to several hours. The ratio of isocyanate groups to active hydrogen atoms can be freely selected as long as it is 1 or more, but it is necessary that free isocyanate groups remain in the obtained urethane prepolymer.

The content of free isocyanate groups in the urethane prepolymer may be not more than 10% by weight, but is preferably not more than 7% by weight in consideration of the stability of the aqueous urethane polymer solution after blocking. Is preferred.

The obtained urethane prepolymer is preferably blocked with bisulfite. The mixture is mixed with an aqueous bisulfite solution, and the reaction is allowed to proceed with good stirring for about 5 minutes to 1 hour. The reaction temperature is preferably set to 60 ° C. or lower. Thereafter, the mixture is diluted with water to an appropriate concentration to obtain a heat-reactive water-soluble urethane composition. When the composition is used, it is adjusted to an appropriate concentration and viscosity.
When heated to about 200 ° C., the bisulfite of the blocking agent is dissociated, and the active isocyanate group is regenerated. Thus, a polyurethane polymer is generated by a polyaddition reaction occurring within or between molecules of the prepolymer, or It has the property of causing addition to other functional groups.

As an example of the resin containing a blocked isocyanate group described above, Daiichi Kogyo Seiyaku Co., Ltd.
A typical example is Elastron, a trade name of the company. Elastron is obtained by blocking an isocyanate group with sodium bisulfite, and is water-soluble due to the presence of a carbamoyl sulfonate group having strong hydrophilicity at the molecular terminal.

When the coating liquid is prepared by mixing the copolymerized polyester resin (X) and the resin (Y) containing a blocked isocyanate group used in the present invention, the resin (X) and the resin (Y) are mixed. The weight ratio is (X) :( Y) = 90:
10 to 10:90 are preferred, and more preferably (X):
(Y) = 80: 20 to 20:80. If the ratio of the resin (X) to the solid content is less than 10% by weight, the coatability on the base film is poor, and the adhesiveness between the surface layer and the film becomes insufficient. When the ratio of the resin (Y) to the solid content is less than 10% by weight,
Practical adhesiveness cannot be obtained with a UV-curable hard coat.

In the present invention, it is preferable to use an aqueous coating liquid as the coating liquid for forming the easily adhesive layer (B). Various additives such as an antistatic agent, a UV absorber plasticizer, a pigment, an organic filler, and a lubricant may be mixed with the composition of the aqueous coating solution as long as the adhesive property is not lost. Further, since the coating liquid is aqueous, other water-soluble resins, water-dispersible resins, emulsions, and the like may be added to the coating liquid for improving the performance as long as the contribution effect is not lost.

A catalyst may be added to the aqueous coating solution to promote the thermal crosslinking reaction. For example, various chemicals such as inorganic substances, salts, organic substances, alkaline substances, acidic substances, and metal-containing organic compounds can be used. The substance is used. In order to adjust the pH of the aqueous solution, an alkaline substance or an acidic substance may be added.

When the aqueous coating solution is applied to the surface of the base film (A), a known anionic activator and a nonionic compound are used to increase the wettability of the film and uniformly coat the coating solution. A necessary amount of a nonionic surfactant can be used. The solvent used for the coating liquid is alcohol, such as ethanol, isopropyl alcohol, and benzyl alcohol, in addition to water, in a proportion of 50% of the total coating liquid.
You may mix until it becomes less than weight%. Further, when the content is less than 10% by weight, an organic solvent other than alcohols may be mixed in a range where it can be dissolved. However, the total of alcohols and other organic solvents in the coating liquid is less than 50% by weight.

When the addition amount of the organic solvent is less than 50% by weight, the drying property is improved at the time of coating and drying, and the appearance of the coating film is improved as compared with the case where only water is used. If the content is 50% by weight or more, the solvent evaporates at a high rate, the concentration of the coating solution changes during coating, the viscosity increases, and the coating property decreases, which may cause poor appearance of the coating film. May be a danger such as fire.

The coating amount (solid content weight per unit area of the film) of the easily adhesive layer (B) is 0.05 to 0.50 g.
/ M ² is preferred. When the coating amount is less than 0.05 g / m ² , the adhesiveness becomes insufficient. 0.50 g / m coating amount
^If it exceeds ² , the total light transmittance decreases, which is not preferable.

It is preferable that the filter medium for finely filtering the coating solution has a filter particle size (initial filtration efficiency: 95%) of 25 μm or less. If the filtration particle size exceeds 25 μm, the removal of coarse aggregates tends to be insufficient. Therefore, the coarse aggregates that could not be removed by filtration are spread by the stretching stress in the uniaxial stretching or the biaxial stretching process after coating and drying, and are recognized as aggregates of 100 μm or more, and lower the total light transmittance of the film. Cause.

There is no particular limitation on the type of filter medium for finely filtering the coating solution as long as it has the above-mentioned performance.
Filament type, felt type and mesh type are mentioned. The material of the filter medium for finely filtering the coating solution is not particularly limited as long as it has the above performance and does not adversely affect the coating solution, and examples thereof include stainless steel, polyethylene, polypropylene, and nylon.

The base film (A) was also subjected to high-precision filtration at any place where the molten resin was maintained at about 280 ° C. during melt extrusion in order to remove foreign substances contained in the raw resin. I do. The filter medium used for the high-precision filtration of the molten resin is not particularly limited, but in the case of a filter medium of a stainless sintered body, the removal performance of aggregates and high-melting organic substances mainly composed of Si, Ti, Sb, Ge, and Cu. Excellent and suitable.
The filtration particle size (initial filtration efficiency 95%) of the filter medium used for high-precision filtration of the molten resin is preferably 15 μm or less.
When the filter particle size of the filter medium exceeds 15 μm,
The removal of the foreign matter described above tends to be insufficient. Productivity may be reduced by performing high-precision filtration of the molten resin using a filter medium having a filtration particle size (initial filtration efficiency of 95%) of 15 μm or less, but the optical adhesive film having high total light transmittance may be obtained. Is very suitable for obtaining

Even in the case of fine foreign matter passing through the filter medium in the step of extruding the molten resin, crystallization proceeds around the foreign matter in the process of cooling the sheet-like molten material, which causes non-uniform stretching in the stretching step, A minute difference in thickness is caused, resulting in a lens state. Here, the light is refracted or scattered as if there is a lens, and when observed with the naked eye, it appears larger than an actual foreign substance. This minute difference in thickness can be observed as a difference between the height of the projection and the depth of the depression. The height of the projection is 1 μm or more, and the depth of the depression adjacent to the projection is 0.5 μm or more. , Due to the lens effect, an object having a shape of 20 μm is visually 50 μm.
m, and may be recognized as an optical defect having a size of 100 μm or more. In order to obtain a highly transparent film, it is desirable not to include particles for imparting lubricity in the base film (A). However, the smaller the amount of added particles and the higher the transparency, the finer the irregularities. Optical defects tend to be sharper. Also,
The surface of a thick film is less likely to be quenched than a thin film and tends to be crystallized. Therefore, it is necessary to quench the entire film when preparing an unstretched sheet. As a method for cooling the unstretched sheet, a known method in which a molten resin is extruded from a die onto a rotary cooling drum onto a sheet, and the sheet-like molten material is rapidly cooled while being in close contact with the rotary cooling drum to form a sheet can be applied. . As a method of cooling the air surface (the surface opposite to the surface in contact with the cooling drum) of the sheet-like material, a method of blowing a high-speed air stream to cool the sheet is effective.

Next, a method for producing the optically easy-to-adhere film of the present invention will be described with reference to polyethylene terephthalate (hereinafter referred to as P
ET), but the present invention is not limited to this.

First, pellets of PET (virgin resin) and recycled resin substantially containing no particles for imparting lubricity are sufficiently dried in vacuum, and then supplied to an extruder at about 280 ° C. It is melt-extruded into a sheet, cooled and solidified to form an unstretched PET sheet. At this time, the high-precision filtration is performed at an arbitrary place where the molten resin is kept at about 280 ° C. in order to remove foreign substances contained in the resin.

The obtained unstretched sheet is heated at 80 to 120 ° C.
And stretched 2.5 to 5.0 times in the longitudinal direction with a roll heated to obtain a uniaxially oriented PET film. Further, the end of the film is gripped with a clip, guided to a hot air zone heated to 80 to 180 ° C., and dried to a width of 2.5 to 5.0 in the width direction.
Stretch twice. Subsequently, it is led to a heat treatment zone of 160 to 240 ° C. and heat treated for 1 to 60 seconds to complete the crystal orientation. During this heat treatment step, if necessary, a 1 to 12% relaxation treatment may be performed in the width direction or the longitudinal direction.

At any stage during this step, the above-mentioned aqueous coating solution is applied to at least one surface of the polyester film to form an easily adhesive layer (B). The aqueous coating solution can be applied by any known method. For example, reverse roll coating, gravure coating,
Kiss-coat method, roll brush method, spray coat method, air knife coat method, wire barber coat method,
Examples thereof include a pipe doctor method, an impregnation / coating method, and a curtain coating method. These methods can be performed alone or in combination.

The solid content concentration in the aqueous coating solution is 30% by weight.
Or less, particularly preferably 10% by weight
It is as follows. The film to which the aqueous coating solution has been applied is guided to a tenter for stretching and heat setting, where it is heated to form a stable film by a thermal crosslinking reaction, and becomes a polyester-based laminated film. In order to obtain good adhesion to the ink, the coating amount at this time is 0.05 g / m ² or more, and heat treatment at 100 ° C. for 1 minute or more is required.

The step of applying the aqueous coating solution may be a normal coating step, that is, a step of coating the base film (A) which has been biaxially stretched and heat-set. The in-line coating method of coating is preferred.
More preferably, it is applied before the crystal orientation is completed.

The thickness of the easily adhesive optical film of the present invention is 5
It is preferably from 0 to 300 μm, particularly preferably from 100 to 2 μm.
50 μm. If the film thickness is less than 50 μm, the rigidity becomes insufficient, which is not preferable. On the other hand, if the thickness of the film exceeds 300 μm, it is not preferable because foreign substances which are optical defects existing in the film increase and the total light transmittance decreases.

The thus obtained optically easy-adhesive film is
It has the characteristics of excellent transparency and easy adhesion, and a small increase in haze in the post-processing step. It is a base film for a prism lens sheet, a base film for an AR (anti-reflection) film, and a shatterproof film for a CRT. And the like.

The renewable resin (n) portion of the base film (A) to which the easy-adhesion layer (B) was not applied, which is generated in the film forming step, is appropriately regenerated and regenerated. Can be used as a material for the base film (A), and can be used as a material for the base film (A) of another brand.

The recycled resin (m) of the base film (A) coated with the easy-adhesion layer (B) can be used in the same manner. A portion that cannot be used as the base film (A) of the same brand can be used as a material of the base film (A) of another brand as long as the quality of the other brand is not affected.

[0069]

Next, a method for producing the optically easy-to-adhere film of the present invention will be described with reference to polyethylene terephthalate (hereinafter referred to as PE).
T), but the present invention is not limited to these. In each example, parts and%
Are based on weight. The evaluation of the characteristics in the present specification was performed by the following methods.

(Measurement of Color b * Value) Using a colorimetric colorimeter (ZE2000) manufactured by Nippon Denshoku Industries Co., Ltd., ten optically easy-to-adhesive films were measured. The color b * value of the raw material was measured by placing the raw material in a container having a depth of 30 cm after drying.

Reference Example 1 (1) Preparation of Coating Solution 95 parts of dimethyl terephthalate, 95 parts of dimethyl isophthalate, 35 parts of ethylene glycol, 145 parts of neopentyl glycol, 0.1 part of zinc acetate and 0.1 part of antimony trioxide were used. The mixture was charged in a reaction vessel and transesterification was performed at 180 ° C. for 3 hours.

Next, 6.0 parts of 5-sodium sulfoisophthalic acid was added, the esterification reaction was carried out at 240 ° C. for 1 hour, and then reduced pressure (13 to 0.3 hP) at 250 ° C.
The polycondensation reaction is carried out for 2 hours in a), and the molecular weight is 1950.
0, a polyester resin (X) having a softening point of 60 ° C. was obtained.

30% of the obtained polyester resin (X)
6.7 parts of an aqueous dispersion, 40 parts of a 20% aqueous solution of an isocyanate group-containing self-crosslinkable polyurethane resin (Y) blocked by sodium bisulfite (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron H-3), 0.5 parts catalyst for Elastron (Daiichi Kogyo Seiyaku; product name Cat64) and 4 parts water
4.3 parts and 5 parts of isopropyl alcohol were mixed, 0.6 part of a 10% aqueous solution of an anionic surfactant, and colloidal silica (Nissan Chemical Industries: Snowtex OL, average particle size 40 nm). 1.8 parts of a 20% aqueous dispersion and 1.1 parts of a 4% aqueous dispersion of dry process silica (manufactured by Nippon Aerosil Co., Ltd .; Aerosil OX50, average particle diameter 500 nm, average primary particle diameter 40 nm) were added, and a coating liquid was added. did.

(2) Formation of an easily adhesive film IV obtained by a known continuous polymerization method was 0.62 dl / g.
Of polyethylene terephthalate (PET) (virgin resin: color b * value is 2.8) at 135 ° C.
After drying under reduced pressure (1.3 hPa) for 6 hours, the mixture is fed to an extruder, melt-extruded into a sheet at about 280 ° C., quenched and solidified on a metal roll maintained at a surface temperature of 20 ° C.
A 00 μm cast film was obtained. At this time, the residence time from melting to rapid solidification was set to 6 minutes. Further, as a filter medium for removing foreign matters from the molten resin, a stainless filter medium having a filtration particle size (initial filtration efficiency of 95%) of 15 μm was used.

Next, this cast film is heated to 100 ° C. by 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 speed difference to obtain a uniaxially oriented PET film. Was. Next, the coating liquid was finely filtered through a felt-type polypropylene filter medium having a filtration particle size (initial filtration efficiency: 95%) of 25 μm, applied to both sides of a uniaxially oriented PET film by a reverse roll method, and dried. At this time, the content ratio between the particles A and the particles B was 8, and the content of the particles B was 0.42% by weight in terms of the solid content ratio of the easily adhesive layer. The coating amount was 0.10 g / solid content.
It was m ^2. Subsequently, after coating, the end of the film was gripped with a clip and guided to a hot-air zone heated to 130 ° C., stretched 4.0 times in the width direction after drying, and had a thickness of 100 μm.
Was obtained as a biaxially oriented PET film (adhesive film for optical use).

(3) Treatment of Reclaimed Resin The product portion of the biaxially oriented PET film including the easily adhesive layer, which was generated in the film forming step of Reference Example 1 (2), was pulverized, and the raw material supply section was reduced in pressure in the extruder. And extruded from a nozzle to obtain a regenerated resin (m). Color b * of recycled resin (m)
The value was 5.4.

Similarly, the product portion of the biaxially oriented PET film which does not contain the easy-adhesion layer, which was generated in the film forming step of Reference Example 1 (2), was pulverized, and the raw material supply section was reduced in the extruder under reduced pressure. The resin was melted and extruded from a nozzle to obtain a regenerated resin (n). The color b * value of the reclaimed resin (n) was 4.5.

Example 1 (Use of Recycled Resin) A film material was prepared by mixing the recycled resin (m) at a ratio of 30% and the virgin resin at a ratio of 70%. The film material was dried in the same manner as in Reference Example 1 (2), and a biaxially oriented PET film (easy-adhesive film for optical use) was obtained using the same easy-adhesion layer.

Example 2 Regenerated resin (m) was 10% and regenerated resin (n) was 40%.
% And virgin resin were mixed at a ratio of 50% to prepare a film material. Such a film material is referred to in Reference Example 1.
Dry in the same manner as in (2) and use the same easy-adhesion layer to form a biaxially oriented PET film (easy-adhesion film for optics).
I got

Comparative Example 1 A film material was prepared by mixing 50% of the recycled resin (m) and 50% of the virgin resin. The film material was dried in the same manner as in Reference Example 1 (2), and a biaxially oriented PET film (easy-adhesive film for optical use) was obtained using the same easy-adhesion layer.

Comparative Example 2 Virgin resin 100% was dried at 135 ° C. for 4 hours using air having a dew point of −10 ° C. Hereinafter, Reference Example 1 (2)
A biaxially oriented PET film (an optically-adhesive film for optical use) was obtained using the same easily-adhesive layer as described above.

Table 1 shows the color b * values of the optically-adhesive films obtained in Examples and Comparative Examples. The optically easy-to-use adhesive films obtained in Examples and Comparative Examples were all excellent in adhesiveness and transparency.

[0083]

[Table 1]

The optical adhesive film of the present invention is economical by using a base film containing a recycled resin as a material, and has excellent transparency and excellent adhesive properties.
Further, it has an optically favorable color tone. further,
Conventionally, the optically easy-to-adhesive film using the recycled resin as the base film is a resin of the easily-adhesive layer included in the recycled resin,
When the reclaimed resin melted, it gelled, and when the reclaimed resin melted, it gelled and was attempted to be removed using a filter.If the back pressure of the filter increased, it passed through the filter and was detected as a foreign substance in the film. In the optically easy-adhesive film of the invention, such a disadvantage can be solved.

Continued on the front page F-term (reference) 4F006 AA35 AB35 AB37 BA01 CA05 CA07 CA08 4F100 AK01B AK41B AK42A AK51B AL01B BA02 EJ38A EJ59 EJ86 GB41 JL11 JL11B JL16A JN01 4J002 CF061 CF062 CF071 CF072 A0808

Claims (5)

[Claims] 1. An easy-to-use optically-adhesive film comprising a biaxially oriented polyester film (A) as a base material and a polymer easy-to-adhesive layer (B) formed on at least one surface of the base material, wherein the biaxially oriented polyester film is The film (A) contains, as a material thereof, a recycled resin produced from a biaxially oriented polyester film (a) having at least one surface with a high-polymer easy-adhesion layer (b), and an easily-adhesive film for optical use Characterized by having a color b * value of 7.0 or less. 2. The content of the recycled resin in the biaxially oriented polyester film (A) is 40% by weight or less.
The easy-to-use optical adhesive film according to the above. 3. The easily adhesive optical film according to claim 1, wherein the film material of the biaxially oriented polyester film (A) is prepared by drying under reduced pressure and in the absence of oxygen. 4. The optical adhesive film according to claim 1, wherein the regenerated resin is melted and regenerated in the absence of oxygen. 5. The reclaimed resin polymer easy-adhesion layer (b) comprises:
5. The optically easy-to-use adhesive film according to claim 1, which comprises a copolymerized polyester resin and a polyurethane resin.