JP5837441B2 - Copolyester and copolyester aqueous dispersion using the same - Google Patents

Description

  The present invention relates to a copolyester that can be suitably used as a coating agent for an easily adhesive layer such as an easily adhesive polyester film. More specifically, the present invention relates to a copolyester excellent in easy adhesion, blocking resistance and solvent resistance, and particularly suitable as a coating agent for an optically easily adhesive polyester film.

  Polymer films such as polyester films are used for optical applications such as displays by laminating functional layers such as hard coat layers, and can be easily used as intermediate layers to improve the adhesion between the polymer film and functional layers. It is common to provide an adhesive layer. In this case, in order to eliminate the problem that light interference spots occur when the difference between the refractive index of the polymer film and the functional layer and the refractive index of the easy-adhesion layer increases, the refractive index of the easy-adhesion layer is changed. It has been proposed to increase the refractive index between the polymer film and the functional layer.

  For example, as a polyester for an easy adhesion layer when a hard coat layer is laminated as a functional layer on a polyester film, Patent Document 1 discloses 2,6-naphthalenedicarboxylic acid, aromatic dicarboxylic acid having a sulfonate group and bis ( A copolyester having 4- (hydroxyethoxy) phenyl) fluorene as a copolymerization component has been proposed. Patent Document 2 copolymerizes naphthalenedicarboxylic acid, polymethylenediol having 4 to 10 carbon atoms, or polymethylenedicarboxylic acid. Copolyester as a component, Patent Document 3 includes 2,6-naphthalenedicarboxylic acid, aromatic dicarboxylic acid having a sulfonate group, and a copolymerized polyester having a bisphenol A ethylene oxide adduct, Patent Document 4 discloses 2,6-naphthalenedical. Phosphate, copolyester and ethylene oxide adduct of a copolymer component of an aromatic dicarboxylic acid and bisphenol S has been proposed having a sulfonate group.

However, the copolyester described in Patent Document 1 is applied in the stretching step after coating because the glass transition temperature of the copolyester is high in the in-line coating method that is usually employed when coating on a polyester film. Not only is the layer easily cracked, but the blocking resistance is also insufficient, and improvements are required.
On the other hand, since the copolymer polyester described in Patent Document 2 has insufficient solvent resistance, the easy-adhesion layer is swollen by the solvent of the hard coat coating solution when the hard coat layer is applied without the addition of large particles, Not only does the interface become rough and interference spots occur, but there is also a problem that blocking resistance is insufficient.

In addition, the copolymerized polyester described in Patent Document 3 has a high copolymerization ratio of the ethylene oxide adduct of bisphenol A and thus has improved adhesion under high temperature and high humidity. Since the glass transition temperature is high, not only is the coating layer easily cracked in the stretching step after coating, but there is also a problem that the blocking resistance is insufficient.
Furthermore, the copolyester described in Patent Document 4 has a problem that cracks are likely to occur in the coating layer in the stretching step after coating because the glass transition temperature of the copolyester is high as in Patent Document 1.

JP 2009-242461 A Japanese Patent No. 4547644 JP 2009-202463 A JP 2008-208313 A

  The object of the present invention is to eliminate such problems of the prior art, have low swellability with respect to organic solvents used in coating liquids of functional layers such as hard coat layers (excellent solvent resistance), blocking resistance and easy adhesion. It is another object of the present invention to provide a copolyester that is excellent as a coating agent for an easy-adhesion layer, and that does not easily crack in the coating layer in the stretching process even when applied by an in-line coating method that is usually employed.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention contain 2,6-naphthalenedicarboxylic acid, an aromatic dicarboxylic acid having a sulfonate group and other aromatic dicarboxylic acids as acid components, As a component, bis (4- (hydroxyethoxy) phenyl) fluorene and an ethylene oxide adduct of bisphenol S coexist, and an ethylene oxide adduct of bisphenol A and a polymethylene glycol having 4 to 10 carbon atoms are further included. The inventors have found that a polymerized polyester can simultaneously achieve the above-mentioned problems and have completed the present invention.

（式中、ｎ，ｍはそれぞれ１以上の整数であって、ｎ＋ｍは２〜８である。）」により達成される。 That is, the object of the present invention is “based on the total dicarboxylic acid component of the polyester, the acid component is 50 to 95 mol% of 2,6-naphthalenedicarboxylic acid component, and the aromatic dicarboxylic acid component having a sulfonate group is 1 to 1. 10 mol% and other aromatic dicarboxylic acid components are 1 to 49 mol%, and the diol component is 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene component and is represented by the following formula (1). Polyethylene glycol having an ethylene oxide adduct of bisphenol S and a total of 10 to 60 mol%, an ethylene oxide adduct of bisphenol A represented by the following formula (2) of 10 to 60 mol%, and a carbon number of 4 to 10 Copolyester comprising 20 to 80 mol% of component

(Where n and m are each an integer of 1 or more, and n + m is 2 to 8.) ”.

Moreover, the copolymer polyester of this invention has the preferable aspect that another aromatic dicarboxylic acid component is a terephthalic acid component or an isophthalic acid component, and a C4-C10 polymethylene glycol component is a hexamethylene glycol component. Including those having at least one requirement of being.
Furthermore, according to this invention, the water dispersion which disperse | distributed said copolyester in water is also provided.

  If the copolymerized polyester of the present invention is used, the in-line coating generally used is low in swelling property with respect to various organic solvents used in the coating liquid of a functional layer such as a hard coat layer, excellent in blocking resistance and adhesiveness. However, it is possible to form an easy-adhesion layer in which coating layer cracking hardly occurs in the stretching process, and its industrial value is extremely high.

It is this schematic which shows the evaluation method of blocking resistance in this invention.

  The copolymerized polyester of the present invention is based on the total dicarboxylic acid component of the polyester, the acid component is 50-95 mol% of 2,6-naphthalenedicarboxylic acid component, and the aromatic dicarboxylic acid component having a sulfonate group is 1-10. The diol component is a 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene component and the bisphenol represented by the above formula (1). 10 to 60 mol% in total with the ethylene oxide adduct of S, 10 to 60 mol% of the ethylene oxide adduct of bisphenol A represented by the formula (2), and 20 to 20 polymethylene glycol components having 4 to 10 carbon atoms. It consists of ˜80 mol%.

  When the ratio of the 2,6-naphthalenedicarboxylic acid component as the acid component is less than the lower limit, the swelling with respect to the organic solvent increases (solvent resistance deteriorates), and therefore when the organic solvent in the functional layer coating liquid comes into contact It is not preferable because it not only causes interference spots due to swelling of the coated polyester coating layer but also reduces blocking resistance. On the other hand, when the upper limit is exceeded, it is not preferable because it is difficult to disperse the copolymerized polyester in water to form an aqueous coating solution. In addition, the minimum of the ratio of a preferable 2, 6- naphthalene dicarboxylic acid component is 60 mol%, and also 65 mol%, and an other upper limit is 93 mol% and also 90 mol%.

  In addition, when the ratio of the aromatic dicarboxylic acid component having a sulfonate group is less than the lower limit, the hydrophilicity of the polyester is lowered and the lipophilicity is increased. Therefore, when the copolymerized polyester is dispersed in water to obtain an aqueous coating liquid. Not only is it difficult to disperse in water, but solvent resistance is also lowered, which is not preferable. On the other hand, if the upper limit is exceeded, blocking resistance when applied on a film to form an easy-adhesive film is not preferred. The lower limit of the ratio of the aromatic dicarboxylic acid component having a preferable sulfonate group is preferably 2 mol%, particularly 3 mol% from the viewpoint of solvent resistance, while the upper limit is 8 mol% from the viewpoint of blocking resistance, and further 7 Mol%.

  Examples of the aromatic dicarboxylic acid component having a sulfonate group include a 5-sodium sulfoisophthalic acid component, a 5-potassium sulfoisophthalic acid component, a 5-lithium sulfoisophthalic acid component, and a 5-phosphonium sulfoisophthalic acid component. However, from the viewpoint of improving water dispersibility, a 5-sodium sulfoisophthalic acid component, a 5-potassium sulfoisophthalic acid component, and a 5-lithium sulfoisophthalic acid component are preferable, and among them, a 5-sodium sulfoisophthalic acid component is most preferable.

  In addition to the acid component described above, the copolymerized polyester of the present invention increases water dispersibility and lowers the glass transition temperature of the copolymerized polyester, so that other aromatic dicarboxylic acid components are contained in an amount of 1 to 49 mol%, preferably 5-36 mol% is used in combination. Examples of other aromatic dicarboxylic acid components include isophthalic acid components, terephthalic acid components, and biphenyl dicarboxylic acid components. Among these, an isophthalic acid component and a terephthalic acid component are preferable, and an isophthalic acid component is particularly preferable.

  As an acid component of the copolymerized polyester of the present invention, an acid component other than the aromatic dicarboxylic acid component, for example, an aliphatic dicarboxylic acid component, an alicyclic dicarboxylic acid component, and an oxycarboxylic acid, as long as the object of the present invention is not impaired. Components may be copolymerized in a small amount, but if the amount is too large, the solvent resistance and blocking resistance tend to decrease, so 4 mol% or less, preferably 2 mol% or less, especially 0 mol%. Is preferred.

  Next, a 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene component and an ethylene oxide adduct of bisphenol S represented by the formula (1) are used in combination as the diol component of the copolymer polyester of the present invention. And the ratio of the sum total needs to be 10-60 mol%. When only the ethylene oxide adduct of bisphenol S is used without using it in combination, it is difficult to disperse in water when the copolymerized polyester is dispersed in water to form an aqueous coating solution, although the swelling with respect to the organic solvent is reduced. On the other hand, when only the 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene component is used, the swelling property with respect to the organic solvent is lowered, which is not preferable. By using both of these, the refractive index of the copolyester can be increased while achieving both swellability to an organic solvent and water dispersibility. When the total ratio is less than the lower limit, the refractive index of the copolyester cannot be increased. On the other hand, when the upper limit is exceeded, the Tg becomes too high, and when the coating layer is formed by in-line coating as described above. This is not preferable because the stretchability is lowered and cracks are likely to occur in the coating layer. The lower limit of the total ratio of the preferred bis (4- (hydroxyethoxy) phenyl) fluorene and bisphenol S ethylene oxide adduct is 15 mol%, further 20 mol%, while the upper limit is 55 mol%, further 50 mol%. The ratio of the 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene component and the ethylene oxide adduct of bisphenol S represented by the formula (1) may be larger, but the proportion of each component is 2 It is preferable that it is mol% or more, preferably 5 mol% or more. Furthermore, it is preferable that the ratio of the ethylene oxide adduct of bisphenol S is large.

  Further, the ethylene oxide adduct of bisphenol A represented by the formula (2) needs to be 10 to 60 mol% from the viewpoint of improving the solvent resistance while maintaining water dispersibility and adhesiveness. Yes, the preferred lower limit is 15 mol%, further 20 mol%, while the preferred upper limit is 50 mol%, further 45 mol%. In the formula (2), n and m are each an integer of 1 or more, and n + m needs to be in the range of 2 to 8. When n or m is 0, copolymerization is difficult, whereas n + m is When it exceeds 8, blocking resistance becomes inadequate. In order to lower the glass transition temperature of the copolymerized polyester, n + m is preferably 4 or more, and preferably 6 or less, particularly 4 or less from the viewpoint of blocking resistance. In addition, if a propylene oxide adduct having a side chain is used instead of an ethylene oxide adduct, for example, the adhesion and solubility in a hydrophilic solvent are improved compared to ethylene oxide, but it is preferable because the solvent resistance deteriorates. Absent.

  When the proportion of the polymethylene glycol component having 4 to 10 carbon atoms is less than the lower limit, the Tg of the copolyester increases. On the other hand, when the proportion exceeds the upper limit, the 9,9-bis [4- (2-hydroxyethoxy) described above is exceeded. ) Phenyl] fluorene component and bisphenol S ethylene oxide adduct, or at least one of the ratio of bisphenol A ethylene oxide adduct is less than the lower limit. The lower limit of the proportion of the polymethylene glycol component having 4 to 10 carbon atoms is preferably 25 mol% and further 30 mol%, and the upper limit is 70 mol% and further 60 mol%. Examples of the polymethylene glycol component having 4 to 10 carbon atoms include a tetramethylene glycol component, a pentamethylene glycol component, and a hexamethylene glycol component. The hexamethylene glycol component is particularly preferable from the viewpoint of the effects of the present invention. In trimethylene glycol, the range of decrease in the glass transition temperature of the polymer is small, and a region having more methylene groups than 1,10-decanediol is not very preferable from the viewpoint of deterioration of swelling property.

  The copolymerized polyester of the present invention has, as its diol component, other aliphatic or alicyclic glycols such as ethylene glycol and 1,4 in addition to the components described above, as long as the object of the present invention is not impaired. -Cyclohexanedimethanol or the like may be used in combination, but if the amount is too large, the solvent resistance and blocking resistance tend to decrease, so 5 mol% or less, preferably 3 mol% or less, especially 0 mol%. It is preferable to do this.

The range of preferable intrinsic viscosity of the copolymerized polyester of the present invention is 0.2 to 0.8 dl / g, the lower limit is further preferably 0.3 dl / g, and particularly preferably 0.4 dl / g, and the upper limit is further It is preferably 0.7 dl / g, particularly 0.6 dl / g. Here, the intrinsic viscosity is a value measured at 35 ° C. using orthochlorophenol.
In addition, the glass transition temperature of the copolymerized polyester of the present invention is preferably in the range of 40 to 75 ° C., and more preferably in the range of 45 to 70 ° C., from the viewpoint of coating film formability when in-line coating on the film. It is preferable that it exists in.

  The copolyester of the present invention described in detail above can be produced by a conventionally known polyester production technique. For example, 2,6-naphthalenedicarboxylic acid or an ester-forming derivative thereof, other aromatic dicarboxylic acid such as isophthalic acid or an ester-forming derivative thereof and 5-sodium sulfoisophthalic acid or an ester-forming derivative thereof, hexamethylene glycol, Reacting with 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, bisphenol S ethylene oxide adduct of formula (1) and bisphenol A ethylene oxide adduct of formula (2), monomer or oligomer And then a polycondensation under vacuum to produce a copolyester having a predetermined intrinsic viscosity. At that time, a catalyst for promoting the reaction, for example, an esterification or transesterification catalyst or a polycondensation catalyst can be used, and various additives such as a stabilizer can be added.

  The copolymerized polyester of the present invention is suitably used for an easy-adhesion layer for applying a functional layer on a film such as a polyester film, but when forming an easy-adhesion layer on a polyester film, the polyester film is used. Since the in-line coating method applied when forming a film is preferable, the copolymer polyester is preferably used as an aqueous dispersion. The method for forming the aqueous dispersion is not particularly limited, but for example, it can be produced by the following method.

First, the copolyester is dissolved in a hydrophilic organic solvent having a solubility in water of 1 liter at 20 ° C. or more and a boiling point of 100 ° C. or less and azeotropic with water at 100 ° C. or less. Examples of the organic solvent include dioxane, acetone, tetrahydrofuran, methyl ethyl ketone, and the like. A smaller amount of surfactant can also be added to such a solution.
Next, water is added to the organic solvent in which the copolyester is dissolved, with stirring, preferably with warming and high-speed stirring, to obtain a blue-white to milky white dispersion. A blue-white to milky white dispersion can also be obtained by a method of adding the organic solution to water under stirring.

When the hydrophilic organic solvent is further evaporated and distilled off from the obtained dispersion under normal pressure or reduced pressure, the desired copolymerized polyester aqueous dispersion is obtained. When the copolyester is dissolved in a hydrophilic organic solvent azeotroped with water, water is azeotropically distilled when the organic solvent is distilled off, so that the amount of water is reduced and dispersed in a large amount of water in advance. It is desirable. In addition, if the solid content concentration after distillation exceeds 40% by mass, re-aggregation of the copolyester fine particles dispersed in water is likely to occur, and the stability of the aqueous dispersion is lowered. The solid concentration after distilling off the solvent is preferably 40% by mass or less. On the other hand, there is no particular lower limit of the solid content concentration, but if the concentration is too low, the time required for drying becomes longer, and therefore it is preferably 0.1% by mass or more. The average particle size of the fine particles of the copolyester in the copolyester aqueous dispersion is usually 1 μm or less, preferably 0.8 μm or less.
The aqueous copolymerized polyester dispersion thus obtained can be applied to one or both sides of the film and dried to impart easy adhesion to the film.

  When applying the copolymerized polyester aqueous dispersion, a necessary amount of a surfactant such as an anionic surfactant or a nonionic surfactant can be added to the aqueous dispersion and used. Examples of effective surfactants include those that can lower the surface tension to 40 dyne / cm or less to promote wetting when the film is a polyester film, and many known surfactants can be used. Examples include polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate, alkyl sulfonate, alkyl sulfosuccinate, quaternary ammonium chloride, alkyl amine Examples thereof include hydrochloride and sodium dodecylbenzenesulfonate.

You may add an antistatic agent, a filler, a ultraviolet absorber, a lubricant, a coloring agent, etc. to a polyester water dispersion as needed.
A filler may be added to the polyester aqueous dispersion. Examples of the filler to be added include silica, silicone, titanium oxide, aluminum oxide, magnesium sulfate, barium sulfate, calcium carbonate, tin oxide, and zirconium oxide. The average particle diameter of the particles is preferably 20 to 500 nm, and it is desirable to contain 1 to 10% by mass based on the mass of the copolyester. When the content of the particles is less than the lower limit, the anti-blocking effect due to the particles is not sufficiently exhibited. When the content exceeds the other upper limit, the haze of the obtained film tends to deteriorate.

  In the present invention, the film to which the copolymerized polyester aqueous dispersion is applied is preferably a polyester film, and particularly preferably a film made of polyethylene terephthalate or a copolymer obtained by copolymerizing this with another copolymer component. The polyester film may be an unstretched film, a uniaxially stretched film, or a biaxially stretched film, but a biaxially stretched film is preferred.

  Such a polyester film can be produced by applying a method known per se. For example, a biaxially stretched polyethylene terephthalate film melts polyethylene terephthalate, extrudes it into a sheet, cools it with a cooling drum to obtain an unstretched film, and then stretches the unstretched film in a biaxial direction and heat-fixes it. If so, it can be produced by heat relaxation treatment. Since the properties of the surface properties, density, and thermal shrinkage of the film at that time vary depending on the stretching conditions and other production conditions, the conditions can be appropriately selected as necessary. For example, in the above production method, polyethylene terephthalate is melted at a temperature of Tm + 10 ° C. to Tm + 30 ° C. (where Tm is the melting point of polyethylene terephthalate) and extruded to obtain an unstretched film. Or in the transverse direction) at a temperature of Tg-10 ° C. or Tg + 50 ° C. (where Tg is the glass transition temperature of polyethylene terephthalate) at a magnification of 2 to 5 times, and then the direction perpendicular to the stretching direction (first-stage stretching is In the case of the longitudinal direction, the second stage is the transverse direction), and a biaxially stretched film can be obtained by stretching at a temperature of Tg to Tg + 50 ° C. at a magnification of 2 to 5 times. In this case, the area stretch ratio is preferably 9 to 22 times, more preferably 12 to 22 times. Thereafter, the obtained film is preferably heat-set at a temperature of (Tg + 60) to Tm ° C., for example, 200 to 240 ° C. The heat setting time is, for example, 1 to 60 seconds.

The step of applying the aqueous copolymerized polyester dispersion of the present invention to the polyester film is not particularly limited. Usually, after the aqueous copolymerized polyester dispersion is applied to an unstretched film or a uniaxially stretched film, it is dried by heating and then further stretched. An in-line coating method is common, and among them, a method in which the film is stretched in the width direction after being applied to a film uniaxially stretched in the machine direction, or a method in which biaxial stretching is performed after being applied to an unstretched film is preferable.
Application | coating is possible by a conventional method, for example, it can apply | coat using a kiss coat, a reverse coat, a gravure coat, a die coat etc. The coating amount is preferably 0.01 to 5 μm (dry) in terms of the final layer thickness after drying, more preferably 0.01 to 2 μm (dry), and most preferably 0.01 to 0.3 μm (dry). .

  The easy-adhesive polyester film thus obtained has high adhesive strength, excellent heat resistance, water resistance, and blocking resistance, and also suppresses swelling when a coating liquid using an organic solvent such as a hard coat layer is applied. For example, it is useful as an optical material such as a packaging material, a magnetic card, a magnetic tape, a magnetic disk, an optical material, a printing material, a graphic material, a photosensitive material, and a decorative material.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited only to these Examples. Each characteristic value was measured by the following method. Moreover, the part in an Example means a weight part unless there is particular notice.

(1) Solvent resistance (swelling ratio in organic solvent)
The copolyester is passed through sieve 1 in the order of 5 mesh (mesh opening 4000 μm) wire mesh sieve 1 and 9 mesh (mesh opening 2000 μm) wire mesh sieve 2 in this order. 40 g of chips that did not pass were sampled. Then, 100 mL of ethyl acetate was poured into a beaker containing the sampled chips and left for 1 hour. Thereafter, the chip was taken out on the sieve 2, taken out, allowed to stand for 2 hours in an atmosphere of 23 ° C. and 50% RH, mass was measured, and the swelling ratio was calculated by the following formula.
Swelling ratio (%) = (mass after immersion−mass before immersion) / mass before immersion × 100
When the obtained swelling rate was less than 15%, the swelling property was good. On the other hand, when the swelling rate was 15% or more, the swelling property was poor.

(2) Solubility in hydrophilic solvent 2 g of the copolymerized polyester in a chip state was placed in a flask connected with a cooling reflux tube, 20 mL of tetrahydrofuran (THF) was poured, and the mixture was heated to reflux for 3 hours. Then, after cooling to room temperature and allowing to stand for 12 hours, it is visually confirmed that there is no undissolved chip. If there is no undissolved chip, the solubility is good. It was.

(3) Glass transition temperature (Tg)
Measurement was performed with a product name: DSC 2920 Modulated DSC manufactured by TA Instrument. The measurement was performed at a heating rate of 20 ° C./min.

(4) Polyester film with easy-adhesion layer Polyethylene terephthalate having an intrinsic viscosity of 0.65 measured in orthochlorophenol at 35 ° C. is melt-extruded to obtain an unstretched film having a thickness of 158 μm. After stretching 3.5 times, a coating solution prepared later was applied to one side of a uniaxially stretched film so that the coating amount after drying was 20 mg / m ² . After that, the film was stretched in the transverse direction (direction perpendicular to the machine axis direction and the thickness direction) at 3.9 times at 105 ° C., and heat-treated at 200 ° C. for 4.2 seconds, and biaxially stretched with an easy-adhesion layer having a thickness of 12 μm. A polyester film was obtained.

(5) Adhesiveness The UV curable composition having the following composition is applied to the surface of the easy-adhesive layer side of the polyester film provided with the easy-adhesive layer on one side prepared in the above (4) using a Mayer bar, Immediately after drying at 70 ° C. for 1 minute, the film was cured by irradiating with a high-pressure mercury lamp with an intensity of 80 W / cm for 30 seconds to form a hard coat layer having a thickness of 5 μm. On the hard coat layer, Scotch tape no. 600 (manufactured by 3M), a width of 19.4 mm and a length of 8 cm was attached so that no air bubbles would enter. The sample was leveled with a manual load roll described in C2701 (1975), and this sample was peeled T-shaped at a head speed of 300 mm / min using a Tensilon UM-11 manufactured by Toyo Baldwin Co., Ltd., between 5 cm. Then, the surface of the polyester film after peeling was observed, and evaluation was made with ○ indicating that the hard coat layer was not peeled and × indicating that peeling was observed. In the T-peeling, the laminate is taken with the scotch tape side down, and the gap between the chucks is 5 cm.
<UV curable composition>
Pentaerythritol acrylate: 45% by mass
N-methylolacrylamide: 40% by mass
N-vinylpyrrolidone: 10% by mass
1-hydroxycyclohexyl phenyl ketone: 5% by mass

(6) Blocking resistance Two sheets of the polyester film prepared in the above (4) with an easy-adhesion layer cut to 10 cm in the machine axis direction and 20 cm in the lateral direction are prepared. And a surface not provided with an easy-adhesion layer were overlapped, and a pressure of 0.6 kg / cm ² was applied to the entire surface in an atmosphere of 60 ° C. × 80% RH for 17 hours. At one end of the sample in the lateral direction of the film, 1 cm from the end is folded back so as to be T-shaped, sandwiched by the chuck of the Tensilon UM-11, and along the lateral direction of the film at a speed of 10 cm / min in the T-direction. The average peel force per 10 cm width was calculated by dividing the integrated stress applied when completely peeled by the peel length, and evaluated according to the following criteria.
○: Average peel force is less than 380 mN / 10 cm ×: Average peel force is 380 mN / 10 cm or more

(7) Measurement of refractive index The copolyester was dried into a plate at 90 ° C. and measured with an Abbe refractometer (D line 589 nm).

[Example 1]
100 parts of dimethyl 2,6-naphthalenedicarboxylate, 48 parts of dimethyl isophthalate, 8 parts of dimethyl 5-sodiumsulfoisophthalate, 60 parts of 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, bisphenol S ethylene 42 parts of oxide adduct, 48 parts of hexamethylene glycol, 55 parts of bisphenol A ethylene oxide adduct (n + m = 4 in the above formula (2)) are charged into a transesterification reactor, and 0.1 part of tetrabutoxy titanium is added thereto. Then, the temperature was controlled at 230 ° C. in a nitrogen atmosphere, and the resulting methanol was distilled off to conduct a transesterification reaction.
Next, 0.5 part of Irganox 1010 (Ciba Geigy) was added to the reaction system, and then the temperature was gradually raised to 255 ° C., the pressure inside the system was reduced to 1 mmHg, and a polycondensation reaction was performed. A copolyester of 0.359 dl / g was obtained.
Table 1 shows the composition of the obtained copolymer polyester.

<Preparation of copolymerized polyester aqueous dispersion>
20 parts of the obtained copolyester was dissolved in 80 parts of tetrahydrofuran, and 180 parts of water was added dropwise to the resulting solution under high-speed stirring at 10000 rpm to obtain a bluish milky white dispersion. Subsequently, this dispersion was distilled under a reduced pressure of 20 mmHg to distill off the tetrahydrofuran. Thus, a polyester aqueous dispersion having a solid content concentration of 10% by mass was obtained. The average particle size of the fine particles of the copolyester in this aqueous dispersion was measured using SA-CP4L manufactured by Shimadzu Corporation and found to be 0.12 μm.

<Preparation of coating solution>
To 180 parts of the obtained polyester aqueous dispersion, 2 parts of nonionic surfactant: polyoxyethylene nonylphenyl ether (HLB = 12.8), 0.5 part of silica having an average particle size of 0.03 μm as a filler, and 618 parts of water was added to prepare a coating solution.
Table 1 shows the characteristics of the polyester film with an easy-adhesion layer using the obtained copolymerized polyester aqueous dispersion and coating solution.

[Examples 2-8, Comparative Examples 1-13]
A copolymer polyester shown in Table 1 was obtained in the same manner as in Example 1 except that the type and amount of the copolymer component were changed so that the composition shown in Table 1 was obtained. Subsequently, a copolymer polyester aqueous dispersion and a coating solution were prepared in the same manner as in Example 1 except that these copolymer polyesters were used.
Table 1 shows the characteristics of the polyester film with an easy-adhesion layer using the obtained copolyester, copolyester aqueous dispersion, and coating solution. In addition, the copolyester whose solubility in the hydrophilic solvent was x was not evaluated further.
In Comparative Examples 6, 10, 12, and 13 having a high glass transition temperature of the copolyester, cracks were observed in the easily adhesive layer.

  In Table 1, NDA is 2,6-naphthalenedicarboxylic acid component, IA is isophthalic acid component, TA is terephthalic acid component, SA is sebacic acid component, NSIA is 5-sodium sulfoisophthalic acid component, and BPA-4 is Sanyo Chemical Industries Bisphenol A ethylene oxide 4 mol adduct component (New Pole BPE-40) manufactured by Sanyo Kasei Kogyo Co., Ltd. and BPA-2 are bisphenol A ethylene oxide 2 mol adduct components (New Pole BPE-20T), BP-23P Is the propylene oxide adduct component of bisphenol A (Newpol BP-23P) manufactured by Sanyo Chemical Industries, BPEF is the 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene component, and BPS is the formula (1) Bisphenol S ethylene oxide adduct component shown, HMG is hexa Chi glycol component, TMG is tetramethylene glycol component, C10G is decamethylene glycol, PEG is polyethylene glycol having a number average molecular weight of 200, EG is ethylene glycol, DEG means diethylene glycol.

  If the copolymerized polyester of the present invention is used, the in-line coating generally used is low in swelling property with respect to various organic solvents used in the coating liquid of a functional layer such as a hard coat layer, excellent in blocking resistance and adhesiveness. It is possible to form an easy-adhesion layer in which cracking in the coating layer does not easily occur even when coating is performed by the above, and it is particularly useful as a coating agent for an optical easy-adhesion film.

1 Coating layer 2 Film 3 Travel direction of chuck when measuring peel force

Claims (4)

Based on the total dicarboxylic acid component of the polyester, the acid component is 50 to 95 mol% of 2,6-naphthalenedicarboxylic acid component, 1 to 10 mol% of aromatic dicarboxylic acid component having a sulfonate group, and other aromatic dicarboxylic acids. The acid component is 1 to 49 mol%, the diol component is a 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene component and an ethylene oxide adduct of bisphenol S represented by the following formula (1). The total is 10 to 60 mol%, the ethylene oxide adduct of bisphenol A represented by the following formula (2) is 10 to 60 mol%, and the polymethylene glycol component having 4 to 10 carbon atoms is 20 to 80 mol%. Copolyester.

(In the formula, n and m are each an integer of 1 or more, and n + m is 2 to 8.)   The copolyester according to claim 1, wherein the other aromatic dicarboxylic acid component is a terephthalic acid component or an isophthalic acid component.   The copolymer polyester according to claim 1 or 2, wherein the polymethylene glycol component having 4 to 10 carbon atoms is hexamethylene glycol.   A copolyester aqueous dispersion in which the copolyester according to any one of claims 1 to 3 is dispersed in water.

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