JP2018062105A - Easily-adhesive laminated polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily-adhesive laminated polyester film that is of a color tone suitable for display members, has reduced surface defects, and has excellent transparency.SOLUTION: An easily-adhesive laminated polyester film has an easily-adhesive layer on at least one side of a laminated polyester film. The laminated polyester film has, as an outermost layer, a layer containing 0.005-0.030 wt.% of silica particles with an average particle diameter [d] of 1.8-3.5 μm and a pore volume of 0.6-1.5 ml/g. The outermost layer has a thickness of ([d]×0.4)-([d]×1.4)μm, the easily-adhesive layer contains a water-soluble resin and a cured product of crosslinker, and the easily-adhesive laminated polyester film has a haze of 1.0% or less.SELECTED DRAWING: None

Description

  The present invention can be used as a backlight film for liquid crystal displays, a hard coat film for touch panels, and a base film for conductive films, has excellent film color tone, hardly causes scratches on the film surface during film formation, and has excellent transparency. The present invention relates to an easily adhesive laminated polyester film.

  Conventionally, transparent polyester films have been used as backlight films for liquid crystal displays, hard coat films for touch panels, and base films for conductive films. Polyester films for these applications have a tendency to increase yellowness due to the color of LED light sources as well as transparency. There is also a need to reduce surface defects.

  For example, Patent Document 1 proposes an easy-adhesive laminated transparent film, but the film color tone is not considered.

  Patent Document 2 proposes a laminated transparent film with easy adhesion and few optical defects. However, the optical defect mentioned here is detected by transmitted light, and the film surface defect confirmed by reflected light is not considered.

JP 2009-269172 A JP 2011-140140 A

  The present invention has been made in view of the above circumstances, and its object is to provide an easily-adhesive laminated polyester film having a yellowish color tone suitable for display member applications, having few surface defects, and excellent in transparency. It is in.

  As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be easily solved by a polyester film having a specific configuration, and have completed the present invention.

  That is, the gist of the present invention is an easily adhesive laminated polyester film having an easily adhesive layer on at least one surface of the laminated polyester film, and the laminated polyester film has an average particle diameter [d] of 1.8 as an outermost layer. A layer containing 0.005 to 0.030% by weight of silica particles having a pore volume of 0.6 to 1.5 ml / g and a thickness of the outermost layer ([d] × 0.4) to ([d] × 1.4) μm, the easy-adhesion layer contains a water-soluble resin and a cured product of a cross-linking agent, and the haze is 1.0% or less. It exists in the polyester film.

  ADVANTAGE OF THE INVENTION According to this invention, the easily adhesive laminated polyester film excellent in transparency with few color defects suitable for a display member use can be provided, and the industrial value of this invention is high.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
In the following, “mass%” and “wt%” and “part by mass” and “part by weight” have the same meaning.
[Laminated polyester film]
The polyester used for the laminated polyester film in the present invention is obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like. Among these, PET has a good balance between physical properties and cost, and is the most frequently used polyester.

  The polyester used in the present invention may be a copolymer containing a third component as long as it is within 10 mol%, preferably within 5 mol% in total. Examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, and sebacic acid, and examples of the glycol component include ethylene glycol and diethylene glycol. , Propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like. Further, together with these components, a small proportion of unsaturated polybasic acids such as maleic acid, fumaric acid, itaconic acid and the like, and hydroxycarboxylic acids such as p-hydroxybenzoic acid and p- (β-hydroxyethoxy) benzoic acid. Can be used. The ratio of the unsaturated polybasic acid component and the hydroxycarboxylic acid component is preferably 10 mol% or less, more preferably 5 mol% or less.

  The laminated polyester film of the present invention is a laminated film having at least two layers of an outermost layer (A layer) and a polyester layer (B layer) in which silica particles are blended. As the laminated structure, A layer / B layer, A layer / B layer / A layer or A layer / B layer / C layer (C layer means a layer having a particle content different from that of A layer, May not be contained.) And the like.

  The polyester used in the B layer of the laminated polyester in the present invention is a conventionally known method, for example, polyester obtained by direct polycondensation of dicarboxylic acid and diol, or the presence of a polymerization catalyst after transesterification of lower alkyl ester of dicarboxylic acid and diol. Examples thereof include polyesters subjected to a condensation polymerization reaction below. As the polymerization catalyst, a known catalyst such as an antimony compound, a germanium compound, or a titanium compound can be used. Preferably, the film has a color tone with reduced “dullness” by using a polyester in which the amount of the antimony compound is zero or 100 ppm or less as antimony. Can be obtained. Although a recyclable raw material may be used, it is preferable to use a recyclable raw material in which the original material is controlled because the yellowishness increases when a coating agent is included. The polyester used for the polyester layer (B layer) is a total of antimony, germanium, titanium derived from the polymerization catalyst, phosphorus and magnesium derived from the reaction assistant, preferably 1000 ppm or less, more preferably 700 ppm or less, particularly preferably 500 ppm or less. Preferably there is.

The polyester used for the outermost layer (A layer) of the laminated polyester in the present invention may be the same as the B layer, but is preferably a polyester that is further polymerized to reduce the oligomer content under reduced pressure by heating or in an inert gas stream such as nitrogen. . The intrinsic viscosity of the polyester is preferably 0.70 dl / g or more, more preferably 0.75 to 0.93 dl / g.
In addition, the manufacturing method of polyester used as said C layer may be the same method as polyester used for said A layer or B layer.

  The silica particles contained in the outermost layer (A layer) are preferably in the form of irregular lumps, and are secondary particles formed by agglomeration of primary particles usually having a particle size of several nm to several tens of nm, and are appropriately deformed when the film is stretched. The average particle diameter [d] of the silica particles is 1.8 to 3.5 μm, preferably 2.0 to 3.4 μm, and more preferably 2.1 to 3.1 μm. When silica particles with an average particle size of less than 1.8 μm are used, when an easy-adhesion layer is laminated, scratches are likely to occur due to contact between the metal coater and the film when an aqueous coating solution is applied after longitudinal stretching. Winding property is deteriorated. On the other hand, when the average particle diameter exceeds 3.5 μm, the graininess on the film surface becomes strong and the film surface quality is deteriorated.

It is important that the amount of silica particles contained in the outermost layer (A layer) is 0.005 to 0.030% by weight. Preferably it is 0.010-0.028 weight%, More preferably, it is 0.015-0.025 weight%. When the blending amount of the silica particles is less than 0.005% by weight, the running property and winding property of the film are adversely affected. On the other hand, when the silica particles are added in an amount exceeding 0.030% by weight, the haze is increased, the transparency is poor, and the color tone b ^* value is also increased.

The thickness of the outermost layer (A layer) is 0.4 to 1.4 times, preferably 0.5 to 1.3 times the average particle diameter [d] of the silica particles. When the thickness of the outermost layer (A layer) is less than 0.4 times the average particle diameter d of the silica particles, the thickness of the outermost layer becomes too thin and the variation in the extrusion amount of the polyester of the A layer becomes large. Film production becomes difficult. On the other hand, when the thickness of the outermost layer (A layer) exceeds 1.4 times the average particle diameter d of the silica particles, the haze increases and the transparency deteriorates. The color tone b ^* value also increases. In addition, when both surfaces are A layers, the thickness of each outermost layer (A layer) is calculated.
As a method for measuring the thickness of the outermost layer (A layer), the cross section of the film is observed with an SEM, the frequency distribution with respect to the position from the film surface is obtained for at least 100 particles, and the maximum frequency is halved from the surface layer. A method of setting the position to the thickness of the outermost layer (A layer) and a method of calculating and obtaining from the resin discharge amount to be sent to the outermost layer (A layer) during film production and the total resin discharge amount are mentioned.

The pore volume of the silica particles contained in the outermost layer (A layer) is 0.6 to 1.5 ml / g, preferably 0.8 to 1.4 ml / g, more preferably 1.0 to 1. .4 ml / g. When the pore volume is less than 0.6 ml / g, the silica particles are hardly deformed when the film is stretched, large voids are generated around the particles, and the haze of the film is increased. On the other hand, when the pore volume exceeds 1.5 ml / g, the deformation of the silica particles becomes large when the film is stretched, and the unevenness of the film surface becomes difficult to appear. For this reason, the amount of particles is increased in order to ensure the surface roughness necessary for the film running property and the winding property, so that the color tone b ^* value is increased.

[Easily adhesive layer]
The easy-adhesive laminated polyester film of the present invention is provided with an easy-adhesive layer on at least one side of the laminated polyester film. By providing this easy-adhesion layer, the adhesion to various functional layers is improved.
In addition, when it has A layer only in the outermost layer of the single side | surface of a laminated polyester film, the surface which provides an easily bonding layer may be the A layer side in a laminated polyester film, or the other side, A layer side It is preferable that

It is essential that the easy-adhesion layer contains a water-soluble resin, and it is preferable that the easy-adhesion layer is composed mainly of this. Specific types of water-soluble resins include ester resins, urethane resins, acrylic resins, vinyl resins, epoxy resins, amide resins, and the like. Especially, it is preferable that at least 1 sort (s) is selected from the group which consists of ester resin, urethane type resin, and an acrylic resin.
Further, the skeleton structure of the water-soluble resin may substantially have a composite structure by copolymerization or the like. Examples of the water-soluble resin having a composite structure include acrylic resin-modified polyester, acrylic resin-modified polyurethane, vinyl resin-modified polyester, and vinyl resin-modified polyurethane.

  The glass transition temperature (Tg) of these water-soluble resins is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, and particularly preferably 40 ° C. or higher. When the glass transition temperature is less than 20 ° C., sufficient blocking resistance may not be obtained when an easy-adhesive layer is formed. Furthermore, it is preferable that the glass transition temperature of water-soluble resin is 140 degrees C or less. If the glass transition temperature exceeds 140 ° C., sufficient stretchability may not be obtained in the process of stretching the easy adhesion layer together with the laminated polyester film.

  10-80 weight% is preferable and the mixture ratio of the water-soluble resin in the said easily bonding layer has more preferable 20-75 weight%. When less than 10% by weight of the water-soluble resin is blended, the adhesion with the laminated polyester film tends to be inferior.

  It is important that a cross-linking agent is contained in the easy-adhesion layer. As specific types, melamine resins, epoxy resins, and oxazoline resins are generally used. In this respect, a melamine resin is preferable. The blending ratio of the crosslinking agent in the easy adhesion layer is preferably 20 to 80% by weight.

  The thickness of the easy-adhesion layer in the present invention is usually in the range of 0.02 to 0.5 μm, preferably 0.03 to 0.3 μm, as the final dry thickness. When the thickness of the easy adhesion layer is less than 0.02 μm, the adhesion tends to be inferior. On the other hand, when the thickness of the easy-adhesion layer exceeds 0.5 μm, the films are likely to adhere to each other, and particularly when the coated film is re-stretched to increase the strength of the film, There is a tendency to stick easily. The above problem of sticking appears particularly when the same easy-adhesion layer is formed on both sides of the film.

  Furthermore, in the easy-adhesion layer in the easily-adhesive laminated polyester film of the present invention, it is preferable to contain inert particles as necessary for improving slipperiness. Examples of the inert particles include inorganic inert particles and organic inert particles. Examples of the inorganic inert particles include silica sol, alumina sol, calcium carbonate, titanium oxide and the like. Examples of the organic inert particles include fine particles containing a single or copolymer of polystyrene resin, polyacrylic resin, and polyvinyl resin, or crosslinked particles obtained by combining these with a crosslinking component. These inert particles preferably have a softening temperature or decomposition temperature of 200 ° C. or higher, more preferably 250 ° C. or higher, particularly 300 ° C. or higher. When the average particle diameter of the inert particles is (P) and the average film thickness of the easy-adhesion layer is (L), the ratio of P to L (P / L) is usually 1/3 to 3, and further 1/2 It is preferable to select so as to be in the range of ˜2. If P / L is less than 1/3, the slipperiness tends to be inferior. If P / L exceeds 3, the particles tend to fall off.

  In the easy-adhesive laminated polyester film of the present invention, the aqueous coating liquid for providing the easy-adhesive layer is optionally provided with a surfactant, an antifoaming agent, an applicability improver, and a thickener. In addition, a small amount of additives such as low molecular weight antistatic agents, organic lubricants, antioxidants, ultraviolet absorbers, dyes and pigments may be contained. These additives may be used alone or in combination of two or more as necessary.

  The easy-adhesion layer in the present invention may be formed only on one side of the laminated polyester film or on both sides. When it is formed only on one side, a functional layer different from the above easy-adhesion layer can be formed on the opposite side as necessary to give other characteristics. In addition, in order to improve the applicability | paintability and adhesiveness to the film of the aqueous coating liquid used in order to form an easily bonding layer and another functional layer, you may perform a chemical process and an electrical discharge process before application | coating. Moreover, in order to further improve the surface characteristics, a discharge treatment may be performed after the easy-adhesion layer is formed.

[Easily adhesive laminated polyester film]
Although the thickness of the easily-adhesive laminated polyester film of this invention is not specifically limited, Usually, it is the range of 15-300 micrometers, Preferably it is the range of 20-200 micrometers. When the thickness of the film is smaller than 15 μm, the handleability of the film is poor and the workability of the functional layer may be deteriorated. On the other hand, when the thickness of the film is larger than 300 μm, the mechanical load at the time of film formation becomes large, and the productivity may be lowered.

  The haze of the easily adhesive laminated polyester film of the present invention is 1.0% or less, preferably 0.8% or less, more preferably 0.6% or less, and particularly preferably 0.5% or less. A film having a haze exceeding 1.0% does not ensure the transparency intended by the present invention.

The color tone b ^* value of the easily adhesive laminated polyester film of the present invention is preferably 0.4 or less. When the color tone b ^* value exceeds 0.4, the yellowness of the film increases, which is not preferable as a film for display applications. Reduction of the yellowishness of the film can be achieved by reducing the polymerization catalyst and the reaction aid or reducing the content of silica particles in the entire film.

  About the easily adhesive laminated polyester film of this invention, the surface roughness Ra of an easily bonding layer becomes like this. Preferably it is 3-10 nm, More preferably, it is 4-8 nm. When the film surface roughness Ra is less than 3 nm, the slipping property is lowered, and defects such as scratches and air between the films are difficult to escape, and a roll-shaped defect tends to occur on the roll. On the other hand, when the film surface roughness Ra exceeds 10 nm, the haze increases and the transparency tends to decrease.

  The easily-adhesive laminated polyester film of the present invention may contain additives such as dyes, ultraviolet absorbers, antistatic agents, antioxidants, and fluorescent brighteners as necessary.

  Next, although the manufacturing method of the easily-adhesive laminated polyester film of this invention is demonstrated concretely, as long as the structural requirements of this invention are satisfied, it is not specifically limited to the following illustrations.

  When producing the easy-adhesive laminated polyester film of the present invention, as a method for forming the easy-adhesive layer, (i) after forming the extruded unstretched film in one direction, the easy-adhesive layer is formed, and then in the vertical direction. A method of stretching, (ii) a method of forming an easy-adhesion layer before stretching the extruded unstretched film, and then a method of biaxially stretching, (iii) a method of forming an easy-adhesion layer after biaxially stretching the extruded unstretched film The method of doing is mentioned. In the present invention, (i) a method in which an easy-adhesion layer is formed after the extruded unstretched film is stretched in one direction and then stretched in the vertical direction is preferable.

The method (i) will be described below.
Polyester chips that have been dried and appropriately blended are supplied to a plurality of extruders, and heated to a temperature equal to or higher than the melting point of each polyester to be melted. Next, the molten polymer is merged by a feed block through a gear pump and a filter and extruded from a die as a co-extruded laminated molten sheet. Subsequently, the molten sheet is rapidly cooled to below the glass transition temperature on a rotary cooling drum to obtain an amorphous unstretched film. At this time, in order to improve the flatness of the unstretched film, the adhesion between the unstretched film and the rotating cooling drum may be improved by an electrostatic application adhesion method, a liquid application adhesion method, or the like.
And a coextrusion laminated uniaxially stretched film is obtained by extending | stretching an unstretched film in the longitudinal direction (longitudinal stretching) using a roll extending | stretching machine. The stretching temperature at this time is stretched in a temperature range of minus 10 ° C. to plus 40 ° C. of the glass transition temperature (Tg) of the raw material resin. The draw ratio is preferably 1.5 to 6.0 times, more preferably 2.0 to 5.0 times. Furthermore, longitudinal stretching may be performed in only one stage, or may be performed in two or more stages.
The laminated polyester film before providing an easily bonding layer is obtained by the above method. Depending on the configuration of the raw materials and the apparatus, various layered configurations such as 2 types, 3 layers, 2 types, 2 layers, 3 types, 3 layers, etc. can be used, but at least the outermost layer on one side is the A layer.

Thereafter, an aqueous coating solution for providing an easy-adhesion layer on the surface of the laminated polyester film is applied. As a method for applying the coating solution, there can be used a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, etc. shown in Yuji Harasaki, Tsuji Shoten, published in 1979, “Coating Method”.
In the present invention, the surface on which the aqueous coating solution is applied may be the A layer side or the opposite side of the laminated polyester film, but is preferably the A layer side.

  Thereafter, the film is guided to a tenter and stretched (laterally stretched) in the width direction of the uniaxially stretched film using a tenter stretcher to obtain a laminated biaxially stretched film.

  The stretching temperature at this time is stretched in a temperature range of + 50 ° C. from the glass transition temperature (Tg) of the raw material resin. The draw ratio is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.0 times. Further, the transverse stretching may be performed only in one stage, or may be performed in two or more stages. And the coextruded laminated film which has an easily bonding layer on the film surface is manufactured by heat-processing a biaxially stretched film. The heat treatment temperature at this time is preferably (Tm-6) ° C. to (Tm-100) ° C., where Tm is the melting point of the polyester used for the surface layer of the coextruded laminated film (the outermost polyester layer (A layer)). The heat setting time is 1.5 to 10 seconds. Moreover, when heat-treating a biaxially stretched film, it is preferable to relax in the film width direction, and it is more preferable to perform relaxation within 6% with respect to the width of the biaxially stretched film.

In addition, the aqueous coating liquid may be subjected to stretching in the width direction after sufficiently evaporating before stretching, after moisture evaporates in the stretching process from the film heating process before the stretching process by the tenter stretching machine, You may perform a extending | stretching process with undried and make it dry at the time of the heat setting after extending | stretching. Furthermore, predetermined drying may be performed before the stretching step, and the drying may be completed by heat setting after stretching.
Film heating before the stretching process by a tenter stretching machine can be performed by increasing the temperature stepwise by providing a plurality of heating zones having different temperatures, and reaching the temperature range of + 50 ° C. from the glass transition temperature (Tg) in the stretching zone. preferable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measurement methods and terms used in the examples and the present invention are defined as follows.

(1) Average particle diameter of particles After dissolving the raw resin containing the particles in a PTM solvent (phenol: tetrachloroethane = 3: 2 (volume ratio)), the same volume of chloroform is added, and the particle concentration is suitable for measurement. Therefore, it was diluted appropriately with a solvent of PTM solvent / chloroform = 1: 1. The adjusted solution was put in a measurement cell, and the average particle size was measured using a microtrack HRA manufactured by HONEYWELL.

(2) Particle pore volume The specific surface area of the particle was measured by gas adsorption method, the pore diameter was determined by the BJH method from the nitrogen desorption isotherm, and the pore volume was calculated assuming that the shape of the pore was a cylinder.

(3) Thickness of outermost layer (A layer) The cross section of the film is observed with an SEM, the frequency distribution with respect to the position from the film surface is obtained for at least 100 particles, and the position from the surface layer at which the maximum frequency becomes 1/2 is determined. The thickness was the outermost layer (A layer).

(4) Film color tone b ^*
Measurement was performed using a spectroscopic color difference meter SE6000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

(5) Haze of film The haze of the film was measured using a split-type turbidimeter NDH4000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

(6) Film surface roughness Ra
The easy adhesion layer was measured using a stylus type surface roughness measuring instrument SE3500 (manufactured by Kosaka Laboratory). However, the vertical magnification was 100,000, the cut-off value was 80 μm, and the measurement length was 2.5 mm.

(7) Scratch defect on the film surface A sample film of 1 square meter was scratched by each of “transmitted light under indoor fluorescent lamp” and “reflected light of halogen lamp in dark room” (fine scratches, scratch-like defects, protrusions) It was confirmed whether a pattern etc.) was visible. When scratches could be confirmed, the number was determined, and scratch defects on the film surface were judged according to the following evaluation criteria. When used as a display application, a level of ○ is required.
<Evaluation criteria>
○: Scratches cannot be confirmed by transmitted light under indoor fluorescent lamps or reflected light from halogen lamps.
Δ: There are no scratches that can be confirmed by the transmitted light under the indoor fluorescent lamp, but there are 1 to 3 scratches that can be confirmed by the reflected light of the halogen lamp.
X: There is one or more scratches that can be confirmed by the transmitted light under the indoor fluorescent lamp. Alternatively, there are four or more scratches that can be confirmed by the reflected light of the halogen lamp.

(8) Transparency of film The haze value of the film was defined by the following evaluation criteria.
<Evaluation criteria>
○: Transparency is good when the haze value of the film is 0.7% or less. Δ: Transparency is slightly good when the haze value of the film is 0.7 to 1.0%. ×: The haze value of the film exceeds 1.0%. Poor transparency

(9) Easy adhesion An acrylic photo-curing resin (KAYANOVA FOP-1700 manufactured by Nippon Kayaku Co., Ltd.) is applied to the surface of the easy adhesion layer so that the thickness after curing is 6 μm, and a high-pressure mercury lamp with an energy of 120 W / cm Was used for irradiation for about 10 seconds at an irradiation distance of 100 mm to form an acrylic photocured layer. After the acrylic photocured layer is formed, a crosscut is made in the photocured layer so that there are 100 grids in a 1-inch width. Evaluate by The evaluation criteria are as follows.
<Evaluation criteria>
◎: Number of cross-cut peeled is 0 ○: Number of cross-cut peeled is 1 or more and 10 or less △: Number of cross-cut peeled is 11 or more and 20 or less ×: Number of cross-cut peel is 21 or more

(10) Surface quality of film The surface of the sample film was observed obliquely under an indoor fluorescent lamp, and the surface texture was evaluated according to the following evaluation criteria.
<Evaluation criteria>
○: There is no graininess on the film surface.
X: The film surface has a graininess.

(11) Appearance of roll The appearance of the roll surface and the end face when rolled up was determined according to the following evaluation criteria.
<Evaluation criteria>
○: The roll surface has almost no wrinkles or protrusions and the end faces are aligned.
Δ: Almost no wrinkles on the roll surface, but some flaw-like defects occur and the end faces are slightly uneven.
X: Wrinkles and protrusions are generated on the roll surface, or the end face is extremely uneven.

(Raw material adjustment)
・ Polyester a
Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, 0.09 parts by weight of magnesium acetate tetrahydrate as a catalyst is placed in the reactor, the reaction start temperature is set to 150 ° C., and the reaction gradually proceeds with the distillation of methanol. The temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially completed. This reaction mixture was transferred to a polycondensation tank, 0.04 part of ethyl acid phosphate and 0.04 part of antimony trioxide were added as a stabilizer and a polymerization catalyst, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure and finally 0.3 mmHg. After performing the polycondensation reaction for 4 hours, the polymer was discharged under nitrogen pressure to obtain polyester a having an intrinsic viscosity of 0.62.

・ Polyester b
In the production of polyester a, the reaction mixture was transferred to a polycondensation tank, and then an ethylene glycol slurry of amorphous bulk silica particles having a pore volume of 1.25 ml / g was used. The polycondensation reaction was carried out for 4 hours. That is, 0.04 part of ethyl acid phosphate and 0.04 part of antimony trioxide were added as a stabilizer and a polymerization catalyst, and the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. The polymer was discharged under nitrogen pressure to obtain a polyester b having an intrinsic viscosity of 0.62 containing 0.1% by weight of irregularly shaped massive silica particles having an average particle size of 2.3 μm.

・ Polyester c
In the production of polyester b, an ethylene glycol slurry of amorphous bulk silica particles having a pore volume of 1.6 ml / g is added to contain 0.1% by weight of amorphous bulk silica particles having an average particle diameter of 2.4 μm. A polyester c having an intrinsic viscosity of 0.63 was obtained.

・ Polyester d
In the production of polyester b, an ethylene glycol slurry of amorphous bulk silica particles having a pore volume of 0.44 ml / g is added to contain 0.1% by weight of amorphous bulk silica particles having an average particle diameter of 2.0 μm. A polyester d having an intrinsic viscosity of 0.63 was obtained.

・ Polyester e
Using a twin screw extruder with a vent, cross-linked styrene-acrylic organic particles having an average particle size of 6.0 μm are blended with polyester a so as to have a concentration of 0.1% by weight, melt kneaded, and an intrinsic viscosity of 0.58. Of polyester e was obtained.

・ Polyester f
Polyester a was solid-phase polymerized at 220 ° C. under vacuum to obtain polyester f having an intrinsic viscosity of 0.75.

Example 1:
A mixture of 85/15 (weight ratio) of polyester a and polyester b forming the outermost layer (A layer) was fed to a vented twin screw extruder (sub). Moreover, after supplying polyester a which forms a polyester layer (B layer) to another twin-screw extruder with a vent (main) and melting at a melting temperature of 280 ° C., the molten polymer from each extruder is passed through a gear pump and a filter. Then, they were merged by a feed block, taken up on a casting drum through a die, and an unstretched film of 2 types and 3 layers was obtained. The unstretched film thus obtained was fed into a longitudinal stretching roll, first stretched 3.5 times at a film temperature of 85 ° C., and then the coating thickness after stretching and drying the aqueous coating liquid A having the composition described below on one side. The film was applied to a thickness of 0.05 μm, led to a tenter, and stretched 4.5 times in the transverse direction at 100 ° C. to obtain a biaxially oriented film. Next, the obtained biaxially oriented film was guided to a heat setting zone and heat-treated at 230 ° C. to obtain an easily-adhesive laminated polyester film having a thickness configuration described in Table 1 below.
Table 1 shows various physical properties of the obtained easily-adhesive laminated polyester film.

The aqueous coating liquid A contains the following components in the following proportions.
1) 65% by weight of water-based polyurethane
Propion as a chain extender to a polyester polyol consisting of terephthalic acid (10 mol%), isophthalic acid (40 mol%), ethylene glycol (8 mol%), diethylene glycol (32 mol%), neopentyl glycol (6 mol%) Aqueous polyurethane containing acid dimethanol (4 mol) and isophorone diisocyanate as isocyanate 2) Cross-linking agent 30% by weight
Water-soluble melamine compound (hexamethoxymethylmelamine)
3) Inert particles 5% by weight
Silica sol with an average particle size of 0.05μm

Example 2:
The mixture of polyester a and polyester b forming the outermost layer (A layer) having a ratio of 77/23 (weight ratio) was supplied to a twin screw extruder with a vent (sub), and the thickness configuration described in Table 1 below An easy-adhesive laminated polyester film was obtained under the same conditions as in Example 1 except that the laminated polyester film was obtained. Table 1 shows various physical properties of the obtained easily-adhesive laminated polyester film.

Example 3:
Easy under the same conditions as in Example 2 except that a mixture of polyester f and polyester b forming the outermost layer (A layer) having a ratio of 91/9 (weight ratio) was supplied to a twin screw extruder with a vent (sub). An adhesive laminated polyester film was obtained. Table 1 shows various physical properties of the obtained easily-adhesive laminated polyester film.

Comparative Example 1:
A mixture of polyester a and polyester c forming the outermost layer (A layer) in a ratio of 70/30 (weight ratio) was supplied to a twin-screw extruder with a vent, and a polyester film having a thickness structure described in Table 2 was obtained. A laminated film was obtained under the same conditions as in Example 1 except that it was obtained. Table 2 shows various physical properties of the obtained laminated film.

Comparative Example 2:
A laminated film was obtained under the same conditions as in Example 2 except that a mixture of polyester a and polyester e forming the outermost layer (A layer) having a ratio of 77/23 (weight ratio) was supplied to a twin-screw extruder with a vent. It was. Table 2 shows various physical properties of the obtained laminated film.

Comparative Example 3:
A laminated film was obtained under the same conditions as in Example 2 except that a mixture of polyester a and polyester d forming the outermost layer (A layer) having a ratio of 77/23 (weight ratio) was supplied to a twin-screw extruder with a vent. It was. Table 2 shows various physical properties of the obtained laminated film.

Comparative Example 4:
A laminated film was obtained under the same conditions as in Example 2 except that a mixture of 65/35 (weight ratio) of polyester a and polyester b forming the outermost layer (A layer) was supplied to a twin-screw extruder with a vent. It was. Table 2 shows various physical properties of the obtained laminated film.

Comparative Example 5:
A laminated film was obtained under the same conditions as in Example 2 except that a mixture of polyester a and polyester b forming the outermost layer (A layer) in a ratio of 96/4 (weight ratio) was supplied to a vented twin-screw extruder. It was. Table 2 shows various physical properties of the obtained laminated film.

Comparative Example 6:
A laminated film was obtained under the same conditions as in Example 1 except that the aqueous coating liquid A was not applied. Table 2 shows various physical properties of the obtained laminated film.

In Examples 1 to 3, since the particle characteristics to be blended in the outermost layer, the thickness design of the outermost layer, and the amount of blended particles are appropriate, the film surface is highly transparent and has few surface defects, and the color tone b ^* value is low. There was no yellowishness, and the film surface quality and roll appearance were good.
On the other hand, in Comparative Example 1, irregularly shaped massive silica particles having a very large pore volume were used, so that the particle deformation increased when the film was stretched, and there were problems such as scratch defects on the film surface. In addition, because amorphous bulk silica particles having a very large pore volume were used, the amount of particles b ^* was increased as a result of adjusting the amount of particles blended in order to ensure the surface roughness required for film running and winding properties. became. In Comparative Example 2, since organic particles having an average particle diameter of 6.0 μm were blended, the granularity of the film surface became strong and the surface quality of the film was inferior. Since Comparative Example 3 used amorphous massive silica particles having a very small pore volume, particle deformation during film stretching was small, large voids were generated around the particles, film haze was high, and transparency was poor. . Since Comparative Example 4 had a large amount of particles, the haze was high and the transparency was poor. In Comparative Example 5, since the amount of the particles was small, clear scratches were generated on the film surface, and air defects between the films were difficult to escape during winding, resulting in poor appearance quality of the film and roll. Since the comparative example 6 did not apply | coat the aqueous coating liquid, it was inferior to adhesiveness.

  The film of the present invention is a highly transparent and easy-adhesive co-extrusion laminated biaxially stretched polyester film that has no yellowishness and excellent film surface appearance quality, and is suitably used as a biaxially stretched polyester film substrate for display member applications. can do.

Claims (5)

An easy-adhesive laminated polyester film having an easy-adhesive layer on at least one side of the laminated polyester film,
The laminated polyester film has, as an outermost layer, 0.005 to 0.030 silica particles having an average particle diameter [d] of 1.8 to 3.5 μm and a pore volume of 0.6 to 1.5 ml / g. The outermost layer has a thickness of ([d] × 0.4) to ([d] × 1.4) μm.
The easy-adhesion layer contains a water-soluble resin and a cured product of a crosslinking agent,
An easily adhesive laminated polyester film having a haze of 1.0% or less.   The easily adhesive laminated polyester film according to claim 1, wherein the water-soluble resin is at least one selected from the group consisting of ester resins, urethane resins, and acrylic resins.   The easily adhesive laminated polyester film according to claim 1 or 2, wherein the outermost layer is provided on both sides of the laminated polyester film. An easy-adhesion layer is formed on at least one side of the laminated polyester film, and the haze is 1.0% or less.
As the laminated polyester film, 0.005 to 0.030 weight of silica particles having an average particle diameter [d] of 1.8 to 3.5 μm and a pore volume of 0.6 to 1.5 ml / g in the outermost layer. %, And the outermost layer has a thickness of ([d] × 0.4) to ([d] × 1.4) μm,
The method for producing an easy-adhesive laminated polyester film, wherein the formation of the easy-adhesive layer is a method in which an aqueous coating solution containing a water-soluble resin and a crosslinking agent is applied to the laminated polyester film, and then stretched in a uniaxial direction and dried by heating. .   The manufacturing method of the easily-adhesive laminated polyester film of Claim 4 which apply | coats an aqueous coating liquid to the polyester film previously uniaxially stretched.