JP2022158826A - Polyester resin composition, and laminated polyester film, multilayer laminated fil and oblique reflection film using the same - Google Patents

Abstract

To provide a polyester resin composition which is suitable for a biaxially stretched film which is excellent in optical characteristics, heat resistance and film-forming property, especially, a laminated film, and a film and a laminated film using the same.SOLUTION: A polyester resin composition is polyester having an aromatic dicarboxylic acid unit and an alkylene glycol unit, and contains 90 mol% or more of a naphthalene dicarboxylic acid with respect to the total dicarboxylic acid components, 40 mol% or more and 80 mol% or less of ethylene glycol and 20 mol% or more and 60 mol% or less of a benzenedimethanol component with respect to the total diol components, where a content of a polyalkylene glycol component is 1 wt.% or more and less than 10 wt.% with respect to the mass of the polyester resin composition.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a polyester resin composition, a laminated polyester film, a multilayer laminated film and an obliquely incident light reflecting film using the same.

Polyethylene naphthalate has excellent mechanical properties and heat resistance, and is used in various applications.

However, polyethylene naphthalate has a high melt viscosity, and there is a limit to how high the molecular weight can be increased by melt polymerization, and the resulting polymer becomes brittle. Therefore, various copolymer compositions have been investigated.

For example, Patent Document 1 discloses a technique for improving crystallinity by copolymerizing p-xylylene glycol and a polyoxyalkylene chain. - Polyethylene terephthalate copolymerized with xylylene glycol is disclosed.

Further, Patent Document 2 discloses a crystalline aromatic polyester containing 90 mol % or more of p-xylylene glycol. An aromatic polyester based on is disclosed.

Patent Document 3 discloses a polyethylene naphthalate containing 5 mol % or more and 20 mol % or less of p-xylene glycol and capable of oriented crystallization. Examples include polyethylene naphthalate containing p-xylene glycol and The multi-layer laminated film used is disclosed.

However, with these techniques, when biaxially stretched films for optical use, particularly laminated polyester films with other polyesters, and multilayer laminated polyester films, the polymer fluidity, crystallization properties, etc. are insufficient, and the films It is difficult to obtain the desired properties as

JP-A-7-70301 JP 2012-116914 A JP 2018-100339 A

An object of the present invention is a polyester resin composition suitable for biaxially stretched films, particularly laminated films, which has excellent optical properties, long-term durability, and film formability, and a laminated polyester film, a multilayer laminated film, and a An object of the present invention is to provide an obliquely incident light reflecting film.

That is, the present invention provides a polyester having an aromatic dicarboxylic acid unit and an alkylene glycol unit, containing 90 mol% or more of a naphthalene dicarboxylic acid component relative to the total dicarboxylic acid component, and 40 mol% of ethylene glycol relative to the total diol component. A polyester containing 80 mol% or more, a benzenedimethanol component in a content of 20 mol% or more and 60 mol% or less, and a polyalkylene glycol component content of 1 wt% or more and less than 15 wt% with respect to the mass of the polyester resin composition It is a resin composition.

According to the present invention, it is possible to provide a polyester resin composition excellent in optical properties, long-term durability, and film formability, and further to provide a film and a laminated film using the same. These films can be applied to optical applications such as liquid crystal displays and head-up displays. In particular, they can be provided for applications such as oblique incident light reflection films by forming multilayer laminated films with a controlled refractive index distribution. , which is excellent for oblique incident light reflection.

The polyester resin composition in the present invention is a polyester having an aromatic dicarboxylic acid unit and an alkylene glycol unit, contains 90 mol% or more of a naphthalene dicarboxylic acid component with respect to all dicarboxylic acid components, and ethylene with respect to all diol components. Contains 40 mol% to 80 mol% of glycol, 20 mol% to 60 mol% of benzenedimethanol component, and 1 wt% to 15 wt% of polyalkylene glycol component based on the mass of the polyester resin composition. must be less than

In the polyester resin composition of the present invention, the content of the naphthalene dicarboxylic acid component should be 90 mol % or more based on the total dicarboxylic acid component from the viewpoint of increasing the refractive index. In addition, a dicarboxylic acid component other than the naphthalene dicarboxylic acid component may be contained, but the content thereof must be 10 mol % or less from the viewpoint of increasing the refractive index. , an aromatic dicarboxylic acid component such as an isophthalic acid component.

As the alkylene glycol component of the polyester resin composition of the present invention, the content of ethylene glycol is 40 mol % or more and 80 mol % or less with respect to all diol components from the viewpoint of increasing the refractive index, crystallinity, melt viscosity, and film-forming properties. It is necessary to be In terms of high refractive index, crystallinity, and long-term durability, the content of benzenedimethanol needs to be 20 mol % or more and 60 mol % or less, and more preferably 25 mol % or more and 40 mol % or less. preferable. The benzenedimethanol may be ortho-, meta-, or para-positioned, but 1,4-benzenedimethanol, which is para-positioned, is preferred from the viewpoint of reactivity.

From the viewpoint of the glass transition temperature, the content of polyalkylene glycol in the polyester resin composition of the present invention should be 1% by weight or more and less than 15% by weight based on the mass of the polyester resin composition. Furthermore, the polyalkylene glycol preferably has a number average molecular weight of 200 or more and less than 1,000 from the viewpoints of crystallinity control, film formability, and reactivity in polyester resin production. When the number average molecular weight is 1,000 or more, the polyester resin tends to whiten due to decreased reactivity and incompatibility as the molecular weight increases.

Examples of polyalkylene glycol include polyethylene glycol, polytrimethylene glycol, polytetramethylene glycol, etc. Polyethylene glycol is preferable from the viewpoint of designing the glass transition temperature related to crystallinity and film formability. As for the timing of addition of such polyalkylene glycol, it can be added at any stage from before the transesterification reaction in the production process of the polyester resin to before the start of the polycondensation reaction. It is preferably added before the reaction.

In the polyester resin composition of the present invention, the alkali metal element content is preferably 10 ppm or more and 100 ppm or less with respect to the mass of the polyester resin composition from the viewpoint of heat resistance, and further 80 ppm from the viewpoint of reducing foreign matter. The following are preferable.

The alkali metal element is preferably sodium or potassium from the viewpoint of heat resistance and reduction of foreign matter, and the compound is sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate. It is preferably a hydrate or anhydride such as. As for the timing of addition of the alkali metal compound, it can be added at any stage from the start of the transesterification reaction in the polyester resin production process to before the start of the polycondensation reaction. It is preferably added between the end of the transesterification reaction and the start of the polycondensation reaction.

Glass transition temperature (middle point glass transition temperature) of the polyester resin composition of the present invention: the point where a straight line equidistant from the extended straight line of each base line in the vertical axis direction and the curve of the stepped change part of the glass transition intersect temperature) is preferably 80° C. or higher and 110° C. or lower from the viewpoint of film-forming properties. Specifically, it is the glass transition temperature when 10 mg of the polyester resin composition is melted at 300° C., held for 5 minutes, rapidly cooled to room temperature, and then heated at a heating rate of 16° C./min.

The crystallization energy from the molten state of the polyester resin composition of the present invention is preferably less than 5 J/g from the viewpoint of optical properties. Specifically, 10 mg of the polyester resin composition is melted at 300° C., held for 5 minutes, cooled rapidly to room temperature, then heated to 300° C. at a temperature rising rate of 16° C./min, held for 5 minutes, The peak area of the crystallization peak when cooled at a rate of 16° C./min is the crystallization energy. If the crystallization peak from the molten state is not detected, the crystallization energy is 0 J/g because the material is substantially amorphous.

The melt viscosity of the polyester resin composition of the present invention is preferably 1000 poise or more and 4000 poise or less at 270° C. from the viewpoint of film-forming properties. Polyethylene naphthalate is generally known to have a melt viscosity about three times that of polyethylene terephthalate at the same intrinsic viscosity. can be Therefore, by copolymerizing polyalkylene glycol, it is possible to control the melt viscosity, crystallinity, and glass transition temperature of polyethylene naphthalate. It is possible to produce a precise laminated biaxially stretched film which is superior in terms of performance.

The solution haze of the polyester resin composition of the present invention is preferably less than 1.0% from the viewpoint of transparency when made into a film. Specifically, 2 g of the polyester resin composition is dissolved in 20 mL of a 3/2 (volume ratio) mixed solution of orthochlorophenol/1,1,2,2-tetrachloroethane, and a cell having an optical path length of 20 mm is used to measure haze. Solution haze measured by integrating sphere photoelectric photometry using a meter (HZ-1 manufactured by Suga Test Instruments Co., Ltd.). If the solution haze exceeds 1.0%, irregular reflection of light tends to occur, and the light transmittance of the film may decrease.

In the polyester resin composition of the present invention, known compounds such as antimony compounds, germanium compounds, titanium compounds, and aluminum compounds can be used as polymerization catalysts, but titanium compounds are preferred from the viewpoint of the reactivity of benzenedimethanol. , it preferably contains 10 ppm or more and 70 ppm or less as a titanium element (atom) with respect to the mass of the polyester resin composition.

When the polyester resin composition and polyester film of the present invention are heat-treated at 285° C. for 24 hours under nitrogen flow, the amount of o-chlorophenol insolubles is 3% by weight relative to the polyester composition or polyester film. %, more preferably 1% by weight or less. If the o-chlorophenol-insoluble matter is 3% by weight or more, surface defects due to gel-like foreign matter may occur during long-term film formation. The amount of o-chlorophenol insoluble matter can be reduced by adding a phosphite compound, and the reduction effect can be increased by using a hindered phenol compound in combination.

The polyester resin composition of the present invention preferably contains a phosphite compound from the viewpoint of heat resistance. Phosphite compounds include triphenyl phosphite (manufactured by ADEKA Corporation: Adekastab TPP), diphenylisodecylphosphite (manufactured by ADEKA Corporation: Adekastab 135A), and phenyldiisodecylphosphite (manufactured by SC Organic Chemical Co., Ltd.: Chelex D). , tris(4-monononylphenyl)phosphite (manufactured by ADEKA Corporation: Adekastab 1178), 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5 ] Undecane (manufactured by ADEKA Co., Ltd.: ADEKA STAB PEP-8), tri(monononyl/dinonyl phenyl) phosphite, monooctyldiphenylphosphite, monodecyldiphenylphosphite, bis[2,4-(bis1,1-dimethyl ethyl)-6-methylphenyl]ethyl phosphite, tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylene diphosphite, phenylneopentylene glycol phosphite, bis(2,4-dicyclo Mylphenyl) pentaerythritol diphosphite, tetra(C12-C15 alkyl)-4,4'-isopropylidene diphenyl diphosphite (manufactured by ADEKA Co., Ltd.: Adekastab 1500), 6-[3-(3-tert-butyl- 4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenz[d,f][1,3,2]dioxaphosphepin, tris(2,4-di -tert-butylphenyl) phosphite (manufactured by ADEKA Co., Ltd.: Adekastab 2112/2112RG), 2,2′-methylenebis(4,6-di-tert-butyl-1-phenyloxy)(2-ethylhexyloxy) phosphorous ( ADEKA Corporation: Adekastab HP-10), 3,9-bis(2,6-di-tert-butyl 4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5. 5] Undecane (manufactured by ADEKA Co., Ltd.: Adekastab PEP-36) can be mentioned, and from the viewpoint of reducing o-chlorophenol insolubles, 2,2′-methylenebis(4,6-di-tert-butyl-1 -Phenyloxy)(2-ethylhexyloxy) phosphorous (manufactured by ADEKA Co., Ltd.: Adekastab HP-10), 3,9-bis(2,6-di-tert-butyl 4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (manufactured by ADEKA Co., Ltd.: Adekastab PEP-36) is more preferred.

The content of such a phosphite compound is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, relative to the polyester resin composition from the viewpoint of reducing o-chlorophenol insoluble matter. is preferably

From the viewpoint of heat resistance, the polyester resin composition of the present invention preferably contains a hindered phenol compound in addition to the phosphite compound. Specific hindered phenol compounds include triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate] (BASF Japan Ltd.: IRGANOX245), 1,6-hexane Diol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (BASF Japan Ltd.: IRGANOX259), 2,4-bis-(n-octylthio)-6-(4- Hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine (BASF Japan Ltd.: IRGANOX565), pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl ) Propionate] (BASF Japan Ltd.: IRGANOX1010), 2,2-thio-diethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (BASF Japan Ltd.: IRGANOX1035), Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (BASF Japan Ltd.: IRGANOX1075), N,N'-hexamethylenebis(3,5-di-t-butyl-4 -hydroxy-hydrocinnamamide), 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5- Di-tert-butyl-4-hydroxybenzyl) benzene (ADEKA Co., Ltd.: AO-330), bis (3,5-di-tert-butyl-4-hydroxybenzyl ethyl phosphonate) calcium (BASF Japan Ltd.: IRGANOX1425WL ), tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate (ADEKA Corporation: AO-20), isooctyl-3-(3,5-di-tert-butyl-4 -hydroxyphenyl) propionate, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl) 4-methylphenyl acrylate (Sumitomo Chemical Co., Ltd.: Sumilizer (registered trademark) GM (F) ), 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionyloxy]-1,1-dimethylethyl]-2,4,8,1 0-tetraoxaspiro[5.5]undecane (Sumitomo Chemical Co., Ltd.: Sumilizer (registered trademark) GA-80) and the like can be mentioned. Among them, pentaerythritol tetrakis [ 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (BASF Japan Ltd.: IRGANOX1010) is often used for the purpose of suppressing oxidative decomposition of polyethylene glycol, and is insoluble in o-chlorophenol. 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl) 4-methylphenyl acrylate, 3,9-bis[2-[3-(3-tert -Butyl-4-hydroxy-5-methylphenyl)-propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane (Sumitomo Chemical Co., Ltd.: Sumilizer ( (registered trademark) GA-80) is more preferred.

The content of such a hindered phenol compound is preferably 0.1% by weight or more, more preferably 0.3% by weight, relative to the polyester resin composition from the viewpoint of reducing o-chlorophenol insoluble matter. % or more.

Methods for adding the phosphite compound and the hindered phenol compound include, for example, a method of adding a high concentration to the polyester resin composition, making a master chip, and then diluting and using it during film formation, and a method of using a powder feeder etc. during film formation ( In the case of a liquid, a method of adding with a roller pump, etc.), a method of adding to a reaction tank of a polymerization vessel after completion of the polymerization reaction, stirring and homogenizing, discharging and chipping, etc., but not limited to these not a thing

The polyester resin composition of the present invention can be produced by a conventionally known method.

Specific production examples are shown below, but the present invention is not limited thereto.
86.5 parts by weight of dimethyl naphthalenedicarboxylate, 35.4 parts by weight of ethylene glycol, 17.1 parts by weight of 1,4-benzenedimethanol, and 5.7 parts by weight of polyethylene glycol (number average molecular weight: 400) were charged into a reaction vessel, After dissolving at 180° C., the transesterification catalyst is added with stirring.

As for the timing of addition of the polyalkylene glycol of the present invention, it can be added at any stage from before the transesterification reaction to before the start of the polycondensation reaction. preferable.

As the transesterification reaction catalyst, a compound having a known transesterification ability such as titanium alkoxide, titanium chelate compound, manganese acetate, magnesium acetate, and metal acetate such as calcium acetate can be used. If so, adding 0.05 to 0.06 parts by weight as an ethylene glycol solution will allow the reaction to proceed sufficiently.

After the addition of the transesterification reaction catalyst, the temperature is raised to 240° C. over 3 to 4 hours while distilling off the by-product methanol. As a guideline for the completion of the transesterification reaction, it is preferable that the amount of distilled methanol, which is a by-product, is 90% or more of the theoretical amount (when the reaction is 100%, the amount of methanol twice the molar amount of dimethyl naphthalenedicarboxylate is generated). After completion of the transesterification reaction, various phosphorus compounds as heat stabilizers, antioxidants, antifoaming agents and the like can be added.

Examples of phosphorus compounds include phosphoric acid, phosphorous acid, phosphonic acid, and phosphinic acid compounds. compounds can be used. At this time, it is preferable to use an alkali metal phosphate together in order to improve the heat resistance. The amount of such a phosphorus compound added is 0.022 parts by weight of phosphoric acid and 0.026 parts by weight of sodium dihydrogen phosphate dihydrate with respect to 100 parts by weight of the polyester resin composition. The molar ratio of the phosphorus element becomes around 1.0, and the heat resistance becomes good.

After the addition of the additives such as the phosphorus compound is completed, the reaction product is transferred to a polycondensation apparatus, and a polycondensation reaction catalyst is added. As the polycondensation reaction catalyst, known compounds can be used, and examples thereof include titanium chelate compounds, titanium alkoxides, germanium dioxide, antimony trioxide, antimony acetate, and aluminum catalysts. As for the amount of the polycondensation catalyst to be added, in the case of antimony trioxide, about 0.020 parts by weight is sufficient.

As for the timing of addition of the alkali metal compound of the present invention, it can be added at any stage from the start of the transesterification reaction to before the start of the polycondensation reaction. It is preferable to add it later and before the start of the polycondensation reaction.

After adding the polycondensation reaction catalyst, the pressure inside the apparatus is reduced to 133 Pa or less, the temperature is raised to 290° C. over 3 to 4 hours, and the polycondensation reaction proceeds while distilling off by-products, and the reaction product reaches a predetermined viscosity. The reaction is terminated when the temperature reaches , and the molten polyester is discharged into a water tank. The discharged polyester is quenched in a water bath and cut into chips by a cutter.

A polyester resin composition can be obtained in this way, but the above is just an example, and the raw materials, catalysts and polymerization conditions are not limited to these.

The polyester film of the present invention preferably contains 80% by weight or more of the polyester resin composition of the present invention from the viewpoint of heat resistance and optical properties.
In the laminated film of the present invention, at least one of the polyester resin layers constituting the laminated film preferably contains 80% by weight or more of the polyester resin composition of the present invention, and the other polyester resin layer is a crystalline polyester resin. It is preferably composed of The layer containing 80% by weight or more of the polyester resin composition of the present invention exhibits high optical isotropy (the same refractive index in both the in-plane direction and the perpendicular direction) due to the relaxation of the orientation in the heat treatment step. can be done. On the other hand, in the case of crystalline polyester resin, the difference between the refractive index in the plane direction (in-plane refractive index) and the refractive index in the perpendicular direction (perpendicular refractive index) can be increased by strongly orienting the resin in the stretching process. can be done. By making the refractive index in the plane direction the same for the polyester layer containing 80% by weight or more of the polyester resin composition of the present invention and the layer of the crystalline polyester resin, it is possible to provide a difference in the refractive index in the direction perpendicular to the plane. can.

Next, a preferred method for producing the laminated film of the present invention will be described below using examples using the polyester resin composition and the crystalline polyester resin of the present invention, but the present invention is not limited thereto.

Further, when producing a laminated film made of a plurality of polyester resins, a plurality of resins such as the polyester resin composition and the amorphous polyester resin of the present invention are sent out from different flow paths using two or more extruders, It is sent to the stacking device. As the lamination device, a multi-manifold die, a feed block, a static mixer, or the like can be used. In particular, in order to efficiently obtain the configuration of the present invention, at least two or more separate members having a large number of fine slits are used. It is preferred to use a feedblock containing. When such a feed block is used, the apparatus does not become extremely large, so foreign matter due to thermal deterioration is small, and highly accurate stacking is possible even when the number of layers to be stacked is extremely large. In addition, lamination accuracy in the width direction is remarkably improved as compared with the conventional technology. It also becomes possible to form an arbitrary layer thickness configuration.
The number of layers to be laminated is preferably 100 layers or more, more preferably 500 layers or more, and more preferably 800 layers or more. The upper limit of the number of laminated layers is preferably 3000 layers from the viewpoint of complicating the device.

The molten multilayer laminate thus formed into a desired layer structure is guided to a die, extruded onto a cooling body such as a casting drum, cooled and solidified to obtain a cast film. At this time, it is preferable to use a wire-shaped, tape-shaped, needle-shaped or knife-shaped electrode and bring it into close contact with a cooling body such as a casting drum by means of electrostatic force for rapid solidification. Also preferred is a method in which air is blown from a slit-shaped, spot-shaped, or planar device to adhere to a cooling body such as a casting drum for rapid cooling and solidification, or to adhere to a cooling body with nip rolls for rapid cooling and solidification. The cast film thus obtained is preferably biaxially oriented. Here, biaxial stretching means stretching in the longitudinal direction and the width direction. The stretching may be performed in two directions sequentially or in two directions at the same time. Further, re-stretching may be performed in the longitudinal direction and/or the width direction.

First, the case of sequential biaxial stretching will be described. Here, stretching in the longitudinal direction refers to stretching for imparting molecular orientation in the longitudinal direction to the film, and is usually carried out with a difference in peripheral speed of rolls, and this stretching may be carried out in one step. , may be carried out in multiple stages using a plurality of roll pairs. The stretching ratio varies depending on the type of resin, but is usually preferably from 2 to 15 times, and particularly from 2 to 7 times when the polyester composition of the present invention is used as one of the resins constituting the laminated film. It is preferably used. The stretching temperature is preferably in the range of the glass transition temperature of the resin constituting the multilayer laminated film to the glass transition temperature +100°C.

The uniaxially stretched film obtained in this way is subjected to surface treatment such as corona treatment, flame treatment, plasma treatment, etc., as necessary, and then functions such as easy lubricity, easy adhesion, and antistatic properties are added. It may be applied by in-line coating.

Moreover, stretching in the width direction refers to stretching for giving orientation in the width direction to the film, and is usually stretched in the width direction using a tenter while conveying the film while holding both ends of the film with clips. The stretching ratio varies depending on the type of resin, but is usually preferably 2 to 15 times. When the polyester resin composition of the present invention is used as one of the resins constituting the laminated film, the stretching ratio is 2 to 7 times. It is particularly preferably used. The stretching temperature is preferably in the range of the glass transition temperature of the resin constituting the multilayer laminated film to the glass transition temperature +120°C.

In order to impart flatness and dimensional stability to the film thus biaxially stretched, it is preferable to carry out a heat treatment in a tenter at a temperature not lower than the drawing temperature and not higher than the melting point. The heat treatment improves the dimensional stability of the film. After the heat treatment in this manner, the film is cooled uniformly to room temperature and wound up. In addition, if necessary, relaxation treatment or the like may be used in combination with the heat treatment and slow cooling.

After the heat treatment in this manner, the film is cooled uniformly to room temperature and wound up.
The laminated film of the present invention preferably has a transmittance of 50% or more for light incident perpendicularly to the film surface (at an angle of 0° with respect to the normal to the film surface). Here, the transmittance of vertically incident light of 50% or more specifically means that the average transmittance of the film at a wavelength of 450 to 650 nm is 50% or more, preferably 70% or more. is. In order to obtain such a laminated film, it is achieved by reducing the refractive index difference in the direction parallel to the film surface between two thermoplastic resins as a final product, and the refractive index difference in the direction parallel to the film surface is When is 0.06 or less, the transmittance is easily increased to 50% or more, and when is 0.04 or less, the transmittance is easily increased to 70% or more.
In the laminated film of the present invention, the reflectance (%) when incident at an angle of 70° with respect to the normal to the film surface is the average reflectance at a wavelength of 450 to 650 nm, and the reflectance at 70° is 30. % or more, and more preferably the reflectance at 70° incidence is 50%. In order to obtain such a laminated film, it is achieved by increasing the refractive index difference in the direction perpendicular to the film surface between two thermoplastic resins. If the refractive index difference is 0.8 or more, the reflectance can be easily made 30% or more, and if the refractive index difference is 0.12 or more, the reflectance can be easily made 50% or more.

EXAMPLES The present invention will be described more specifically with reference to examples below.
The physical properties were measured and the effects were evaluated according to the following methods.

(1) Thermal properties of polyester resin composition and film (glass transition temperature, crystallization energy from molten state)
About 10 mg of a sample to be measured was weighed, sealed with an aluminum pan and pan cover, and measured with a differential scanning calorimeter (Q2000 type, manufactured by TA Instruments). In the measurement, the temperature was raised to 300°C in a nitrogen atmosphere, held for 5 minutes, then rapidly cooled, again heated from 20°C to 300°C at a rate of 16°C/minute in a nitrogen atmosphere, held for 5 minutes, and then heated to 16°C/minute. Cool at a rate of minutes. Midpoint glass transition temperature when the temperature is raised at a rate of 16 ° C / min temperature), and the crystallization energy derived from the crystallization observed when cooled at 16°C/min was measured.

(2) Quantitative determination of the amount of alkali metal in the polymer Quantitative determination was carried out by atomic absorption spectrometry (manufactured by Hitachi Ltd.: polarized Zeeman atomic absorption spectrophotometer 180-80, frame: acetylene-air).

(3) Refractive index (optical properties)
After the polyester resin composition was melted at 280 ° C. with a vented twin-screw extruder, through a gear pump and a filter, it was guided to a T-die and formed into a sheet, and then the surface temperature was 25 by applying static electricity. C. to obtain an unstretched sheet having a thickness of 100 .mu.m.
The refractive index of the obtained unstretched sheet was measured according to JIS K7142 (1996) A method.

(4) Solution haze (optical properties)
2 g of the polyester resin composition was dissolved in 20 mL of a 3/2 (volume ratio) mixed solution of orthochlorophenol/1,1,2,2-tetrachloroethane, and a haze meter (Suga Test Instruments It was measured by an integrating sphere type photoelectric photometry using HZ-1) manufactured by Co., Ltd.
The solution haze is an index indicating that the lower the value, the better the transparency.

0.5% or less ・・・ ○
0.6% or more and 1.0% or less ・・・ △
1.1% or more ... x.

(5) Measurement of Melt Viscosity Using a resin dried at 180° C. for 3 hours or more under reduced pressure in a vacuum dryer, measurements were made with Shimadzu Flow Tester CFT-500 A (Shimadzu Corporation). The amount of resin is set at about 5 g and the melt temperature at 270°C. The load was set to 10 N, 20 N, and 50 N (the load was started 5 minutes after starting the sample setting), and the shear rate and melt viscosity at each load were determined. The dice had a diameter of φ1 mm and L=10 mm. The number of measurements for each load is three times, and the numerical data of the melt viscosity and shear rate at each load obtained by calculating the average value of each is graphed, and from the graph, the value of shear rate 100 (1 / sec) asked for

(6) Reflectance/transmittance of laminated film (0-degree transmittance/70-degree reflectance)
A spectrophotometer manufactured by Hitachi, Ltd. (U-4100 Spectrophotometer) was equipped with an attached angle-variable transmission accessory and an attached polarizer made by Gran-Taylor, and the transmittance of wavelengths 250 to 1600 nm at an incident angle of φ = 0 degrees and φ = 70 degrees. was measured.

A transmittance of 70% or more at a wavelength of 250 to 1600 nm at an incident angle of φ=0 degrees and a reflectance of 70% or more at φ=70 degrees were regarded as acceptable.

(7) Long-term durability evaluation (internal haze)
After leaving the resin sheet sample in an atmosphere of 23°C and a relative humidity of 65% for 2 hours, it was heated at 150°C for 2 hours as an accelerated test for evaluating long-term durability. The internal haze was measured using a computer "HGM-2DP". A film having an internal haze of less than 1% as an average of three measurements was accepted.

(8) Film formability (presence or absence of flow marks)
The film formability of the resulting laminated film was judged based on the presence or absence of flow marks, and films with no visible flow marks were evaluated as acceptable.

(9) Quantitative determination of o-chlorophenol (OCP) insolubles A polyester resin composition or polyester film was pulverized with a freeze pulverizer (manufactured by SprexCertiPerp), and 0.5 g was weighed in a 50 ml stainless steel beaker. After vacuum drying at 50° C. for 2 hours using a vacuum dryer, heat treatment was performed at 285° C. for 24 hours under nitrogen gas flow (flow rate 0.5 L/min). This was dissolved in 20 ml of o-chlorophenol at 160° C. for 1 hour and allowed to cool. This solution was filtered using a glass filter (3GP40, manufactured by Shibata Scientific Co., Ltd.), and the glass filter was washed with dichloromethane. The glass filter was dried at 130° C. for 2 hours, and the weight fraction relative to the weight of polyester (0.5 g) was determined from the increased weight of the filter before and after filtration.

Example 1
86.5 parts by weight of dimethyl naphthalenedicarboxylate, 35.4 parts by weight of ethylene glycol, 17.1 parts by weight of 1,4-benzenedimethanol, and 5.7 parts by weight of polyethylene glycol (number average molecular weight: 400) were charged into a reaction vessel. 0.055 parts by weight of manganese acetate tetrahydrate and 0.020 parts by weight of antimony trioxide were added with stirring to initiate the transesterification reaction. While distilling methanol over 3.5 hours, the temperature was raised to 235° C. to complete the transesterification reaction. 0.022 parts by weight of phosphoric acid and 0.026 parts by weight of sodium dihydrogen phosphate dihydrate were added, and excess ethylene glycol was distilled off.

The reactant is transferred to a polycondensation reaction vessel, and after adding 0.1 part by weight of IRGANOX 1010, the pressure is reduced to 133 Pa or less while raising the temperature from 240 ° C., and the temperature is raised to 290 ° C. while distilling off excess ethylene glycol. did. When it reached a predetermined melt viscosity, it was discharged into a water tank and chipped with a strand cutter.

The obtained polyester composition had a glass transition temperature (Tg) of 102° C., a crystallization energy (ΔHmc) of 0 J/g because no crystallization peak was detected from the molten state, and a solution haze of 0.1%. .
The obtained polyester resin composition and polyethylene terephthalate resin (glass transition temperature: 78°C) were put into two single-screw extruders, melted at a temperature of 290°C, and kneaded. Next, the polyester resin composition and the polyethylene terephthalate resin were each passed through five FSS-type leaf disc filters, and then weighed with a gear pump, joined in a lamination device with 801 slits, and alternately in the thickness direction. A laminate having 801 layers was obtained. The method of forming a laminate is performed according to the method described in Japanese Patent Application Laid-Open No. 2007-307893 [0053] to [0056], and the final product has a reflection band of 400 to 1000 nm. there were.

The resulting cast film was heated with rolls set at a temperature of 60° C., stretched 3.7 times in the longitudinal direction of the film with rolls set at a temperature of 90° C., and then cooled once.

The uniaxially stretched film thus obtained was led to a tenter, preheated with hot air at a temperature of 95°C, and then stretched 3.2 times in the film width direction at a temperature of 95°C. The stretched film is directly heat-treated in a tenter with hot air at 240°C, followed by 2% relaxation treatment in the width direction under the same temperature conditions, and then quenching to 100°C, followed by 5% relaxation in the width direction. After treatment, a wound laminated film was obtained.

The physical properties of the obtained laminated film are shown in Table 1. There was no flow mark, both the 70 degree reflectance and the 0 degree transmittance were 70% or more, and the Δhaze value was 1% or less. found to be suitable.

Examples 2-9, Comparative Examples 1-5
A polyester composition and a laminated film were obtained in the same manner as in Example 1, except that the copolymer components were changed. Table 1 shows the evaluation results.

In Example 2, a polyester resin composition and a laminated film were obtained in the same manner as in Example 1, except that 1,3-benzenedimethanol was used. There were no problems with the physical properties of the polymer and the physical properties of the film, and the performance was satisfactory as a film for controlling oblique incident light.

In Examples 3 and 4, polyester resin compositions and laminated films were obtained in the same manner as in Example 1, except that the molecular weight of polyethylene glycol was changed. There were no problems with the physical properties of the polymer and the physical properties of the film, and the performance was satisfactory as a film for controlling oblique incident light.

In Example 5, the refractive index of the film tended to decrease as the amount of polyalkylene glycol was increased, but the performance was satisfactory as a film for controlling oblique incident light.

In Example 6, scattering was observed during the polymerization reaction as the amount of 1,4-benzenedimethanol was increased. rice field.

In Example 7, the refractive index of the film tended to decrease due to the increased amount of dimethyl isophthalate.

In Example 8, the glass transition temperature of the polymer tended to increase due to the reduced amount of polyalkylene glycol, but there were no problems with both the polymer physical properties and the film physical properties, and the performance was satisfactory as a film for controlling oblique incident light.

In Example 9, by increasing the amount of polyalkylene glycol, the refractive index of the polymer was lowered, and the 70-degree reflectance and the 0-degree transmittance tended to decrease. there were.

In Comparative Example 1, since polyalkylene glycol was not added, the glass transition temperature of the polymer was out of the range of the present invention, and the lamination accuracy was disturbed due to the occurrence of flow marks. This resulted in a decline.

In Comparative Example 2, the content of 1,4-benzenedimethanol was outside the range of the semi-invention, and the crystallization energy (ΔHmc) from the molten state was detected. It was confirmed that the Δhaze of the obtained film also increased due to heating. The obtained film had no problem in 70° reflectance and 0° transmittance, but had a Δhaze of more than 1% and was insufficient in long-term durability.

In Comparative Example 3, the content of 1,4-benzenedimethanol was outside the range of the present invention, and as a result of the increase in the amount of scattered matter during the polymerization reaction, the reactivity was poor, and a polymer that could be evaluated for film formation could not be obtained. I didn't.

In Comparative Example 4, the content of the naphthalene dicarboxylic acid component was outside the range of the present invention, and the 70-degree reflectance and the 0-degree transmittance decreased due to the decrease in the refractive index of the polymer, resulting in insufficient optical properties.

In Comparative Example 5, the polyalkylene glycol content was outside the range of the present invention, and the 70° reflectance and 0° transmittance were lowered due to the decrease in the refractive index of the polymer, resulting in insufficient optical properties.

Example 10
A polyester resin composition and a laminate were prepared in the same manner as in Example 1, except that instead of antimony trioxide, tetrabutyl titanate was added at the same time as IRGANOX 1010 so as to be 40 ppm by mass relative to the polyester resin composition. got the film. Table 2 shows the evaluation results. The obtained laminated film had no flow marks, had a 70° reflectance and a 0° transmittance of 70% or more, and had a Δhaze value of 1% or less, and was found to be suitable for an oblique incident light control film. .

Example 11
Using a vented twin-screw extruder, 0.25 parts by weight of Adekastab PEP-36 was added by a powder feeder to 100 parts by weight of the polyester resin composition of Example 1, and the mixture was melt-kneaded at 280°C. , and after discharging into a water tank, chipped with a strand cutter to obtain a polyester resin composition. It was confirmed that o-chlorophenol (OCP)-insoluble matter in the resulting polyester resin composition was 0.7% by weight, which is significantly lower than in Example 1.
Moreover, the obtained polyester resin composition was treated in the same manner as in Example 1 to obtain a laminated film. Table 2 shows the evaluation results. The obtained laminated film had no flow marks, had a 70° reflectance and a 0° transmittance of 70% or more, and had a Δhaze value of 1% or less, and was found to be suitable for an oblique incident light control film. .

Example 12
Using a vented twin-screw extruder, 0.25 parts by weight of Adekastab PEP-36 and 0.5 parts by weight of Sumilizer (registered trademark) GA-80 are added to 100 parts by weight of the polyester resin composition of Example 1. The mixture was added using a powder feeder, melted and kneaded at 280° C., discharged into a water tank, and chipped using a strand cutter to obtain a polyester resin composition. It was confirmed that o-chlorophenol (OCP) insolubles in the resulting polyester resin composition was 0.5% by weight relative to the polyester resin composition, which was lower than in Example 11.
Moreover, the obtained polyester resin composition was treated in the same manner as in Example 1 to obtain a laminated film. Table 2 shows the evaluation results. The obtained laminated film had no flow marks, had a 70° reflectance and a 0° transmittance of 70% or more, and had a Δhaze value of 1% or less, and was found to be suitable for an oblique incident light control film. .

Example 13
Using a vented twin-screw extruder, add 2.5 parts by weight of Adekastab PEP-36 and 5 parts by weight of Sumilizer (registered trademark) GA-80 to 100 parts by weight of the polyester resin composition using a powder feeder. Then, the mixture was melt-kneaded at 280° C., discharged into a water bath, and chipped with a strand cutter to obtain paste chips containing a high concentration of a phosphite compound and a hindered phenol compound.
A laminated film was obtained in the same manner as in Example 1, except that 90 parts by weight of the polyester resin composition of Example 1 and 10 parts by weight of the master chip were blended and supplied to the extruder for film formation. Table 2 shows the evaluation results. The resulting laminated film had o-chlorophenol insoluble matter equivalent to that of the laminated film of Example 12, no flow marks, both 70° reflectance and 0° transmittance of 70% or more, and a Δhaze value of 1. % or less, and was found to be suitable for oblique incident light control films. The physical properties of the polymer in Table 2 are those of the polyester resin composition of Example 1 (physical properties before the addition of the phosphite compound and the hindered phenol compound).

Claims (17)

A polyester having an aromatic dicarboxylic acid unit and an alkylene glycol unit, containing 90 mol% or more of a naphthalene dicarboxylic acid component based on the total dicarboxylic acid component, and 40 mol% or more and 80 mol% or less of ethylene glycol based on the total diol component, A polyester resin composition containing a benzenedimethanol component in a content of 20 mol % or more and 60 mol % or less, and a polyalkylene glycol component in a content of 1 wt % or more and less than 15 wt % relative to the mass of the polyester resin composition. The polyester resin composition according to claim 1, which has a glass transition temperature of 80°C or higher and 110°C or lower. 3. The polyester resin composition according to claim 1, wherein the crystallization energy from the molten state is less than 5 J/g. The polyester resin composition according to claim 1 or 2, wherein the polyalkylene glycol has a number average molecular weight of 200 or more and less than 1,000. The polyester resin composition according to any one of claims 1 to 3, wherein the alkali metal element content is 10 ppm or more and 100 ppm or less based on the mass of the polyester resin composition. The polyester resin composition according to any one of claims 1 to 5, wherein the alkali metal compound is an alkali metal phosphate. The polyester resin composition according to any one of claims 1 to 5, which has a solution haze of less than 1.0%. The polyester resin composition according to any one of claims 1 to 7, which contains 10 ppm or more and 70 ppm or less of the titanium compound as a titanium element (atom) with respect to the weight of the polyester resin composition. The polyester resin composition according to any one of claims 1 to 8, wherein the o-chlorophenol insoluble matter is less than 3% by weight based on the polyester composition when heat-treated at 285°C for 24 hours under nitrogen flow. . The polyester resin composition according to any one of claims 1 to 9, which contains a phosphite compound. 11. The polyester resin composition according to claim 10, which contains a hindered phenol compound. A polyester film containing 80% by weight or more of the polyester resin composition according to any one of claims 1 to 11. A laminated polyester film comprising at least one layer containing 80% by weight or more of the polyester resin composition according to any one of claims 1 to 11. 14. The laminated polyester film according to claim 13, wherein the highest glass transition temperature in differential scanning calorimetry is 110[deg.] C. or less. 15. The polyester film according to any one of claims 12 to 14, wherein the o-chlorophenol-insoluble matter is less than 3% by weight based on the polyester film when heat-treated at 285°C for 24 hours in a stream of nitrogen. 16. The multilayer laminated polyester film according to any one of claims 13 to 15, which has 50 or more layers. An oblique incident light reflecting film comprising the laminated polyester film according to any one of claims 13 to 16.