JP2012068427A - Antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost antireflection film in which adhesion of an antireflection layer is favorable, reflection rate is low, and reflection color unevenness is suppressed.SOLUTION: An antireflection film has a thin film layer that is laminated on a polyester film whose refraction factor is 1.6 to 1.7 via only an easily adhesive layer by a gas phase film forming method. The refraction factor of the thin film layer is smaller than that of the polyester film by 0.15 or more. The easily adhesive layer satisfies the following condition 1, condition 2, or conditions 1 and 2. Condition 1: the absolute value of the difference between the refraction factor of the easily adhesive layer and that of the polyester film is 0.05 or less. Condition 2: the thickness of the easily adhesive layer is 5 nm or over and less than 50 nm.

Description

  The present invention relates to an antireflection film having a thin film layer laminated on a polyester film only by an easy-adhesion layer by a vapor deposition method, and can be produced in detail at low cost, with low reflection and adhesion. The present invention relates to an antireflection film which is good and suppresses occurrence of uneven reflection color.

  An antireflection film is usually mounted on an image display device such as a liquid crystal display, a plasma display, or an organic EL display, or an image display surface of a touch panel.

  As a method of laminating an antireflection film on a substrate such as a glass plate or a resin plate, or a base film such as a plastic film, a method of laminating an antireflection film by applying an antireflection coating, drying and curing (wet Coating method), a method of depositing an antireflection film by a vapor deposition method (dry coating method) such as vacuum deposition, sputtering, or plasma CVD, or a method combining the above two methods (wet and dry method). is there.

  The antireflection film produced by the wet coating method generally has a configuration in which a high refractive index layer and a low refractive index layer are laminated on a base film. The high refractive index layer is usually provided with a hard coat property and has a thickness of 1 μm or more. For this reason, there is a problem that reflection color unevenness easily occurs due to a difference in refractive index between the base film and the high refractive index layer or due to thickness unevenness of the high refractive index layer. In addition, there are problems in that the production efficiency is reduced and the cost of raw materials is increased by recoating the high refractive index layer and the low refractive index layer.

  As the wet and dry method, there is known a method in which a hard coat layer is laminated on a base film by a wet coating method, and an antireflection film is laminated thereon by a vapor deposition method (for example, Patent Document 1). 2). In this method, since a hard coat layer having a relatively large thickness is provided between the base film and the antireflection film, the thickness of the hard coat layer depends on the refractive index difference between the base film and the hard coat layer. Due to the unevenness, there is a problem that unevenness of the reflected color is likely to occur. In addition, there is a problem that the adhesion between the hard coat layer and the antireflection film cannot be secured sufficiently stably.

  On the other hand, the method of laminating an antireflection film by the above-described vapor deposition method (dry coating method) is advantageous for uniformly laminating an ultrathin antireflection film on a substrate film, and is also efficient in production. Is also advantageous.

  It is known that an antireflection film such as a silicon oxide film or a magnesium fluoride film is laminated on a substrate such as a glass plate or a resin plate or a base film such as a plastic film by a vapor deposition method. For example, it is described in Patent Documents 3 and 4 that a magnesium fluoride film is laminated on a glass substrate by a vacuum deposition method, and a magnesium fluoride film or a silicon oxide film is vacuum deposited on a base film such as a polyester film. Patent Documents 5 and 6 describe laminating by a method or a plasma CVD method.

JP-A-8-41230 JP-A-10-195636 Japanese Patent Laid-Open No. 7-104102 JP-A-9-5502 JP 2008-266728 A JP 2009-208429 A

  When an antireflection film is laminated on a heat-resistant substrate such as a glass substrate as described in Patent Documents 3 and 4 by a vapor deposition method, the glass substrate can be heated to a high temperature, and adhesion A good antireflection film can be obtained.

  On the other hand, when an antireflection film is laminated on a base film made of a plastic film such as a polyester film as described in Patent Documents 5 and 6 by a vapor deposition method, the plastic film has low heat resistance. Therefore, there is a problem that the film must be formed at a relatively low temperature, resulting in a decrease in adhesion.

  In order to improve the adhesion between the polyester film and the antireflection film, providing an easy-adhesion layer between them is described in Patent Document 6, but the easy-adhesion layer is not specifically described.

  By providing an easy-adhesion layer between the polyester film and the antireflection film, improvement in adhesion can be expected. However, when a thin film layer (antireflection film) having a refractive index smaller than 0.15 or more with respect to the polyester film is directly laminated on the polyester film only through the easy adhesion layer, simply providing the easy adhesion layer, New problems such as a decrease in anti-reflection property and occurrence of uneven reflection color have occurred.

  Therefore, an object of the present invention is to provide a low-cost antireflection film in which the adhesion of the antireflection film is good, the reflectance is low, and the reflection color unevenness is suppressed.

The above object of the present invention has been achieved by the following invention.
1) a polyester film having a refractive index of 1.6 to 1.7;
An easy-adhesion layer directly laminated on the polyester film;
On the surface opposite to the polyester film side of the easy-adhesion layer, a thin film layer directly laminated by a vapor deposition method,
The refractive index of the thin film layer is 0.15 or more smaller than the refractive index of the polyester film,
And the said anti-adhesion layer satisfies the following condition 1, condition 2, or (condition 1 and condition 2), the antireflection film.
Condition 1: The absolute value of the difference between the refractive index of the easy adhesion layer and the refractive index of the polyester film is 0.05 or less.
Condition 2: The thickness of the easy adhesion layer is 5 nm or more and less than 50 nm.
2) The antireflection film of 1) above, wherein the thickness of the thin film layer is in the range of 50 to 150 nm.
3) The antireflection film according to 1) or 2), wherein the refractive index of the thin film layer is in the range of 1.2 to 1.5.
4) The antireflection film according to any one of 1) to 3), wherein the thin film layer contains a metal fluoride.
5) The antireflection film according to 4), wherein the metal fluoride is magnesium fluoride.

  According to the present invention, it is possible to provide an antireflection film in which the adhesion and antireflection properties of the antireflection film are good and the reflection color unevenness is suppressed. In addition, according to the present invention, an antireflection property can be obtained simply by directly laminating a thin film layer (antireflection film) having a relatively low refractive index on a polyester film having a relatively high refractive index through only an easy adhesion layer. Since a good antireflection film can be obtained, the cost of the antireflection film can be reduced.

  The antireflection film according to the present invention is directly laminated by a vapor deposition method on a polyester film, an easy-adhesion layer directly laminated on the polyester film, and a surface opposite to the polyester film side of the easy-adhesion layer. A thin film layer. That is, a thin film layer is laminated on a polyester film by a vapor deposition method only through an easy adhesion layer.

  The refractive index of the polyester film according to the present invention is 1.6 to 1.7, and it is important that the refractive index of the thin layer film is 0.15 or more smaller than the refractive index of the polyester film.

  The present invention uses a relatively large refractive index (refractive index of 1.6 to 1.7) of a polyester film, and a thin film layer having a refractive index smaller than that of the polyester film by 0.15 or more is simply laminated on the polyester film. Focusing on the fact that an antireflection film having a low reflectance is obtained, the present invention solves the problems in realizing such an antireflection film.

  That is, the present invention solves the problem of adhesion between the polyester film and the thin film layer by interposing an easy adhesion layer, and a new problem due to the interposition of the easy adhesion layer, that is, the reflectance increases. Or problems such as occurrence of uneven reflection color.

The said subject is solved by providing the easily bonding layer of specific conditions. Here, the easy-adhesion layer under specific conditions is an easy-adhesion layer that satisfies the following condition 1, condition 2, or (condition 1 and condition 2).
Condition 1: The absolute value of the difference between the refractive index of the easy adhesion layer and the refractive index of the polyester film is 0.05 or less.
Condition 2: The thickness of the easy adhesion layer is 5 nm or more and less than 50 nm.

  When the easy-adhesion layer is outside the above condition 1, that is, when the absolute value of the difference in refractive index between the easy-adhesion layer and the polyester film is greater than 0.05, the reflectance of the antireflection film increases or the reflection color unevenness This causes inconvenience such as occurrence. From the viewpoint of suppressing such inconvenience, among the conditions 1, the absolute value of the refractive index difference between the easy-adhesive layer and the polyester film is preferably 0.04 or less, more preferably 0.03 or less, and particularly preferably 0. 02 or less is preferable.

  If the easy-adhesion layer is outside the above condition 2, that is, if the thickness of the easy-adhesion layer is 50 nm or more, the reflectance of the antireflection film becomes high, or the reflection color unevenness occurs. If the thickness of the easy adhesion layer is less than 5 nm, the adhesion of the thin film layer is lowered. From the viewpoint of suppressing such inconvenience, among the conditions 2, the thickness of the easy adhesion layer is preferably less than 40 nm, more preferably less than 30 nm, while the lower limit thickness of the easy adhesion layer is preferably 10 nm or more.

(Polyester film)
The polyester film according to the present invention is a general term for a film made of a polymer compound having an ester bond as a main bond chain, and examples thereof include ethylene terephthalate, ethylene-2,6-naphthalate, and butylene terephthalate. And a film having at least one selected from ethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate as a main constituent. Among these films, a polyethylene terephthalate film is particularly preferable from a comprehensive viewpoint such as quality and economy.

  The refractive index of the polyester film according to the present invention is in the range of 1.6 to 1.7. From the viewpoint of obtaining an antireflection film having a low reflectance, the refractive index of the polyester film is preferably larger in the above range, specifically 1.61 or more, more preferably 1.62 or more, and further 1. 63 or more is preferable, and 1.64 or more is particularly preferable. On the other hand, the easy-adhesion layer laminated on the polyester film preferably contains a resin as described later. From the viewpoint of easy adjustment of the refractive index of the easy-adhesion layer containing the resin (condition 1 of the easy-adhesion layer is relatively easy). From the viewpoint of satisfying the above, it is preferable that the refractive index of the polyester film is not so large. Specifically, the upper limit refractive index of the polyester film is preferably 1.69 or less, more preferably 1.68 or less.

  The thickness of the polyester film is suitably in the range of 30 to 300 μm, preferably in the range of 40 to 200 μm, and more preferably in the range of 50 to 150 μm.

(Thin film layer)
The thin film layer according to the present invention is formed by a vapor deposition method. Examples of the vapor deposition method include a vacuum deposition method, a reactive deposition method, an ion beam assisted deposition method, a sputtering method, an ion plating method, a plasma CVD method, etc., and these methods can be used alone or in combination. it can. Among these, a vacuum vapor deposition method, a sputtering method, and a plasma CVD method are preferably used.

  The refractive index of the thin layer film needs to be 0.15 or more smaller than the refractive index of the polyester film. From the viewpoint of obtaining an antireflection film having a low reflectance, the refractive index of the thin film layer is preferably 0.20 or more smaller than the refractive index of the polyester film, and more preferably 0.25 or smaller. The lower limit of the refractive index of the thin film layer is about 0.4 smaller than the refractive index of the polyester film.

  Specifically, the refractive index of the thin film layer is preferably 1.5 or less, more preferably 1.45 or less, and particularly preferably 1.4 or less. The lower limit refractive index of the thin film layer is preferably 1.2 or more, more preferably 1.25 or more, and particularly preferably 1.3 or more.

Examples of the material constituting the thin film layer having a relatively low refractive index as described above include metal oxides and metal fluorides. Examples of the metal oxide include silicon oxide. Examples of the metal fluoride include magnesium fluoride (MgF ₂ ), aluminum fluoride (AlF ₃ ), calcium fluoride (CaF ₂ ), and barium fluoride (BaF _2). ), Strontium fluoride (SrF ₂ ), cryolite (Na ₃ AlF ₆ ), thiolite (Na ₅ Al ₃ F1 ₄ ), sodium fluoride (NaF) and the like.

  Among the substances constituting the thin film layer, a metal fluoride is preferable, and among the metal fluorides, magnesium fluoride is particularly preferable.

  Metal fluoride has a relatively low refractive index, and a thin film layer containing metal fluoride is laminated on a polyester film having a refractive index of 1.6 to 1.7 only through the specific easy-adhesion layer of the present invention. An antireflection film having a low reflectance can be obtained.

  On the other hand, the metal fluoride thin film layer has a problem that it is difficult to obtain adhesion to the polyester film as compared with a thin film layer such as silicon oxide. Therefore, the antireflection film of the present invention is suitable when the thin film layer is formed of a metal fluoride, and particularly suitable when the thin film layer is formed of magnesium fluoride.

  The thickness of the thin film layer is preferably in the range of 50 to 150 nm, more preferably in the range of 80 to 120 nm, and particularly preferably in the range of 90 to 110 nm. If the thickness of the thin film layer is out of the above range, the reflectance tends to increase, which is not preferable.

(Easily adhesive layer)
The easy-adhesion layer according to the present invention needs to satisfy the following condition 1, condition 2, or (condition 1 and condition 2).
Condition 1: The absolute value of the difference between the refractive index of the easy adhesion layer and the refractive index of the polyester film is 0.05 or less.
Condition 2: The thickness of the easy adhesion layer is 5 nm or more and less than 50 nm.

  Hereinafter, the easy adhesion layer of Condition 1 will be described in detail. Such an easy-adhesion layer has an absolute value of the difference in refractive index with the polyester film of 0.05 or less, preferably an absolute value of the difference in refractive index of 0.04 or less, more preferably an absolute value of the difference in refractive index. The absolute value of the difference in refractive index is particularly preferably 0.02 or less.

  The easy-adhesion layer of Condition 1 is an easy-adhesion layer having a relatively high refractive index, and such an easy-adhesion layer can be obtained by containing a high refractive index material such as a resin or metal oxide fine particles having a relatively high refractive index. it can.

  Although it is known to provide an easy-adhesion layer on a polyester film, these easy-adhesion layers are mainly composed of a resin such as a polyester resin, an acrylic resin, or a urethane resin, and the refractive index is usually 1.45 to 1. .54, which is relatively small.

  One embodiment of the easy-adhesion layer of Condition 1 according to the present invention is a resin having a high refractive index by introducing an aromatic ring, a sulfur atom, a bromine atom, or the like into a resin such as a polyester resin, an acrylic resin, or a urethane resin. Is an embodiment using The content of the resin having a high refractive index is preferably 50% by mass or more, more preferably 60% by mass or more, particularly 70% by mass with respect to 100% by mass of the solid content of the easy-adhesion layer. % Or more is preferable. The upper limit content is about 98% by mass.

  As the resin having a high refractive index, a polyester resin having an aromatic ring in the molecule is preferable, and a polyester resin having a condensed aromatic ring in the molecule is more preferable. Examples of the condensed aromatic ring include a naphthalene ring and a fluorene ring.

  The polyester resin is generally obtained by polycondensation from a carboxylic acid component and a glycol component. The polyester resin having a naphthalene ring in the molecule can be synthesized by using a dicarboxylic acid having a naphthalene ring such as 1,4-naphthalenedicarboxylic acid or 2,6-naphthalenedicarboxylic acid as a carboxylic acid component. . The refractive index of the polyester resin having a naphthalene ring in the molecule can be controlled by adjusting the ratio of the dicarboxylic acid having a naphthalene ring in the total carboxylic acid component.

  The polyester resin having a fluorene ring in the molecule can be synthesized by using a compound having a fluorene ring as the carboxylic acid component and / or glycol component. The refractive index of the polyester resin can be controlled by adjusting the content of the compound having a fluorene ring. The polyester resin which has a fluorene ring in a molecule | numerator is described in detail in the international publication number WO2009 / 145075, for example, It can synthesize | combine with reference to it.

  The polyester resin is preferably water-soluble or water-dispersible. A water-soluble or water-dispersible polyester resin can be synthesized by including a trivalent or higher polyvalent carboxylic acid or a dicarboxylic acid having a sulfo group in the carboxylic acid component used for the synthesis of the polyester resin. .

  Another aspect of the easy-adhesion layer under Condition 1 according to the present invention is an aspect in which metal oxide fine particles are contained. The easy adhesion layer of this embodiment is a layer in which metal oxide fine particles are dispersed in a resin. Examples of the resin include an acrylic resin (preferably an acrylic resin having an OH group such as an acrylic resin polyol), a polyester resin (preferably Polyester resin having an OH group such as polyester resin polyol), epoxy resin, urethane resin, styrene-maleic acid graft polyester resin, acrylic graft polyester resin, silicone resin and the like can be used.

As metal oxide fine particles, titanium oxide, zirconium oxide, zinc oxide, tin oxide, antimony oxide, cerium oxide, iron oxide, zinc antimonate, tin oxide-doped indium oxide (ITO), antimony-doped tin oxide (ATO), phosphorus-doped Tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, or the like can be used.
The content ratio of the resin and the metal oxide fine particles is suitably in the range of 100: 10 to 100: 400 by mass ratio, preferably in the range of 100: 20 to 100: 300, particularly 100: 30 to 100: 200. The range of is preferable.

  The thickness of the easy-adhesion layer of Condition 1 according to the present invention is not particularly limited, but is preferably less than 200 nm, more preferably less than 150 nm, further preferably less than 100 nm, and particularly preferably less than 50 nm. The lower limit thickness is 5 nm or more, and preferably 10 nm or more.

  Next, the easy adhesion layer of the condition 2 concerning this invention is demonstrated. The easy adhesion layer has a thickness in the range of 5 nm or more and less than 50 nm. The thickness of the easy-adhesion layer is preferably smaller even within the above thickness range, specifically, less than 40 nm, and more preferably less than 30 nm. The lower limit thickness of the easy adhesion layer is preferably 10 nm or more.

  Although the refractive index of the easy-adhesion layer of Condition 2 is not particularly limited, a range of 1.45 or more and less than 1.60 is preferable, a range of 1.47 to 1.59 is more preferable, and a range of 1.48 to 1.58 is particularly preferable. A range is preferred.

  The easy adhesion layer of Condition 2 is preferably a layer containing a resin such as a polyester resin, an acrylic resin, or a urethane resin as a main component. That is, the resin is preferably contained in an amount of 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more with respect to 100% by mass of the total solid content of the easy-adhesion layer. The upper limit is about 98% by mass.

  The easy-adhesion layer of the present invention is particularly preferably an easy-adhesion layer that satisfies the conditions 1 and 2 at the same time.

  Next, contents common to the easy-adhesion layers of Condition 1 and Condition 2 will be described.

  As described above, the easy-adhesion layer of the present invention preferably contains at least a resin. Although the easy-adhesion layer containing resin is mentioned later in detail, an easy-adhesion layer can be laminated | stacked in-line within the manufacturing process of a polyester film, and it is useful at the point of productivity. The content of the resin in the easy adhesion layer is preferably 20% by mass or more, more preferably 30% by mass or more, and particularly preferably 50% by mass or more with respect to 100% by mass of the solid content of the easy adhesion layer. Preferably there is. The upper limit is about 98% by mass.

  It is preferable that the easily bonding layer of this invention contains a crosslinking agent. Examples of such crosslinking agents include melamine crosslinking agents, oxazoline crosslinking agents, carbodiimide crosslinking agents, isocyanate crosslinking agents, aziridine crosslinking agents, epoxy crosslinking agents, methylolated or alkylolized urea crosslinking agents, and acrylamides. Crosslinking agents, polyamide resins, amide epoxy compounds, various silane coupling agents, various titanate coupling agents, and the like can be used.

  The easy-adhesion layer of the present invention preferably further contains particles. It is preferable for the easy-adhesion layer to contain particles because the slipperiness and blocking resistance are improved. Such particles are not particularly limited, but inorganic particles such as colloidal silica, titanium oxide, aluminum oxide, zirconium oxide, calcium carbonate, carbon black, zeolite particles, acrylic particles, silicone particles, polyimide particles, Teflon (registered trademark) particles. , Organic particles such as crosslinked polyester particles, crosslinked polystyrene particles, crosslinked polymer particles, and core-shell particles.

  The easy-adhesion layer of the present invention is preferably laminated on the polyester film by a wet coating method, and a so-called in-line coating method in which the easy-adhesion layer is further laminated in the production process of the polyester film is preferred. Examples of the wet coating method include a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, and a die coating method.

  When applying the easy-adhesion layer of the present invention on a polyester film, the polyester film surface should be subjected to corona discharge treatment, flame treatment, plasma treatment, etc. as a preliminary treatment for improving coatability and adhesion. Is preferred.

  About the above-mentioned in-line coating method, although the aspect using the polyethylene terephthalate (henceforth PET) film as a polyester film is demonstrated below, this invention is not limited to this.

  PET pellets with an intrinsic viscosity of 0.5 to 0.8 dl / g, which is a raw material for PET film, are vacuum-dried, then supplied to an extruder, melted at 260 to 300 ° C, extruded into a sheet form from a T-shaped die, An unstretched PET film is produced by winding it around a mirror-casting drum having a surface temperature of 10 to 60 ° C. by using an electric application casting method and cooling and solidifying the drum. This unstretched PET film is stretched 2.5 to 5 times in the longitudinal direction (referring to the traveling direction of the film and also referred to as “longitudinal direction”) between rolls heated to 70 to 100 ° C. At least one surface of the uniaxially stretched PET film obtained by this stretching is subjected to corona discharge treatment in air, the wetting tension of the surface is set to 47 mN / m or more, and the coating solution for the easy adhesion layer of the present invention is applied to the treated surface. To do.

  Next, the uniaxially stretched PET film coated with the coating solution is gripped with a clip, guided to a drying zone, dried at a temperature lower than Tg of the uniaxially stretched PET film, raised to a temperature equal to or higher than Tg, and again at a temperature near Tg. And then continuously stretched in the heating zone at 70 to 150 ° C. in the transverse direction (referred to as the direction perpendicular to the film traveling direction, also referred to as “width direction”) 2.5 to 5 times, and subsequently 180 to Heat treatment is performed in a heating zone at 240 ° C. for 5 to 40 seconds to obtain a polyester film in which an easy-adhesion layer is laminated on a PET film in which crystal orientation is completed. In addition, you may perform a 3-12% relaxation process as needed during the said heat processing. Biaxial stretching may be longitudinal, transverse sequential stretching, or simultaneous biaxial stretching, and may be re-stretched in either the longitudinal or transverse direction after longitudinal and transverse stretching.

(Antireflection film)
The antireflection film of the present invention is obtained by laminating a polyester film, an easy-adhesion layer, and a thin film layer in this order without interposing other layers. The easy adhesion layer and the thin film layer may be provided only on one side of the polyester film or on both sides. Further, another layer can be laminated on the thin film layer (on the surface opposite to the polyester film side of the thin film layer) or on the surface opposite to the side on which the thin film layer of the polyester film is laminated.

  The other layer that can be laminated on the thin film layer is preferably a layer that does not affect optical characteristics such as luminous reflectance and reflected color. Examples of such a layer include a layer for reinforcing the film physical properties of the thin film layer, and examples thereof include a fluorine-containing silicone film and a silicon oxide film. The thickness of these layers is preferably 1 to 20 nm.

  Examples of other layers that can be laminated on the side opposite to the side on which the thin film layer of the polyester film is laminated include a near-infrared shielding layer, a color tone adjusting layer, an electromagnetic wave shielding layer, an antiglare layer, and an adhesive layer. .

  According to the present invention, an antireflection film having good antireflection properties at low cost can be obtained. The antireflection property can be expressed in terms of luminous reflectance, but the antireflection film of the present invention preferably has a luminous reflectance of 1.0% or less. Such an antireflection film is formed on a polyester film by vapor phase film formation only through the easy adhesion layer of the present invention (condition 1, condition 2, or an easy adhesion layer satisfying (conditions 1 and 2)). It is obtained by laminating thin film layers such as magnesium fluoride by the method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples. In addition, the measuring method and evaluation method in a present Example are shown below.

(1) Measurement of refractive index of polyester film It was measured with an Abbe refractometer according to JIS K7105 (1999), and the average value of the refractive index in the longitudinal direction and the width direction was taken as the refractive index of the polyester film.

(2) Thickness of easy-adhesion layer A cross-section of the polyester film on which the easy-adhesion layer is laminated is cut into ultrathin sections, and stained with ultrathin sections by RuO4 staining, OsO4 staining, or double staining of both, to obtain a TEM The cross-sectional structure is observed under the following conditions with an electron microscope), and the thickness of the easy-adhesion layer is measured from the cross-sectional photograph.
Measurement device: Transmission electron microscope (H-7100FA type, manufactured by Hitachi, Ltd.)
・ Measurement conditions: Acceleration voltage 100kV
-Sample preparation: frozen ultrathin section method-Magnification: 300,000 times.

(3) Measurement of the refractive index of the easy-adhesion layer In the state where the easy-adhesion layer (thickness of about 100 nm) is laminated on the polyester film having a known refractive index, the reflectance on the easy-adhesion layer side and the thickness of the easy-adhesion layer are determined. The measurement is performed by the method (2) above. The refractive index of the easy adhesion layer is calculated from the reflectance of the easy adhesion layer thus obtained, the thickness of the easy adhesion layer, and the refractive index of the polyester film.
The reflectance is determined by applying a black paint (black magic ink (registered trademark)) after uniformly scratching the polyester film surface opposite to the easy-adhesive layer with # 320-400 water-resistant sandpaper. The reflectance at 550 nm is measured using a spectrophotometer UV-3150 manufactured by Shimadzu Corporation in a state where reflection from the surface opposite to the easy adhesion layer is completely eliminated.

(4) Measurement of the thickness of the thin film layer A cross section of the sample was cut into ultrathin sections, and observed with a transmission electron microscope (H-7100FA type manufactured by Hitachi) at an acceleration voltage of 100 kV (observed at a magnification of 100,000 times). The thickness of the thin film layer is measured from the cross-sectional photograph.

(5) Measurement of refractive index of thin film layer In a state where a thin film layer (thickness of about 100 nm) is laminated on a polyester film having a known refractive index, the reflectance on the thin film layer side and the thickness of the thin film layer are the above (4). Measure with this method. The refractive index of the thin film layer is calculated from the reflectance on the thin film layer side thus obtained, the thickness of the thin film layer, and the refractive index of the polyester film.
The above-mentioned reflectance is obtained by applying a black paint (black magic ink (registered trademark)) after uniformly scratching the surface of the polyester film opposite to the thin film layer with a # 320 to 400 water resistant sandpaper. The reflectance at 550 nm is measured using a spectrophotometer UV-3150 manufactured by Shimadzu Corporation with the reflection from the surface opposite to the thin film layer completely eliminated.

(6) Measurement of luminous reflectance of antireflection film <Preparation of sample for evaluation>
The surface opposite to the side where the thin film layer of the sample is laminated is attached to the glass plate with an adhesive, and black tape is applied to the opposite surface of the glass plate (the surface opposite to the surface where the antireflection film sample is attached). (Nitto Denko No. 21 Toku (BC)) is pasted to prepare a sample for evaluation.
<Measurement>
Using a spectrophotometer (manufactured by Shimadzu Corporation, UV3150PC), the reflectance (single-sided reflection) is calculated in the wavelength range of 380 to 780 nm at an incident angle of 5 degrees from the measurement surface, and the luminous reflectance (in JIS Z8701-1999). The prescribed reflex stimulation value Y) was determined. The spectral solid angle is measured with a spectrophotometer, and the reflectance (single-sided light reflection) is calculated according to JIS Z8701-1999. The calculation formula is as follows.
・ T = K ・ ∫S (λ) · y (λ) · R (λ) · dλ (however, the integration interval is 380 to 780 nm)
T: Single-sided light reflectance S (λ): Standard light distribution used for color display y (λ): Color matching function in XYZ display system R (λ): Spectral solid angle reflectance.

(6) Visual evaluation of uneven reflection color Each sample was cut out to 150 mm x 150 mm, and black adhesive tape ("Vinyl tape No.21 Tokuhaba black" manufactured by Nitto Denko) on the opposite side of the polyester film from the thin film layer. Is attached to prepare a sample for evaluation. This sample was visually observed under a three-wavelength fluorescent lamp in a dark room for uneven reflection color on the surface of the thin film, and evaluated according to the following criteria.
○: Almost no occurrence of uneven reflection color is observed.
X: Generation of uneven reflection color is recognized.

(7) Adhesion After each sample was left in an atmosphere of 60 ° C.-90% RH for 500 hours, 100 pieces of 1 mm ² crosscuts were put on the thin film layer surface of each sample, and cellophane tape manufactured by Nichiban Co., Ltd. The film was peeled rapidly in the direction of 90 ° after being strongly pressed with a finger, and the adhesion was evaluated according to the following criteria based on the remaining number.
○: 90/100 (remaining number / measured number) or more x: less than 90/100 (remaining number / measured number).

(Resin for forming an easy-adhesion layer)
<Polyester resins 1, 2>
By adjusting the content of the fluorene ring in the polyester resin, a water-dispersible polyester resin 1 having a refractive index of 1.64 and a water-dispersible polyester resin 2 having a refractive index of 1.62 were prepared.
<Polyester resin 3>
By adjusting the content of the naphthalene ring in the polyester resin, a water dispersible polyester resin 3 having a refractive index of 1.58 was prepared.
Was prepared.
<Acrylic resin>
A water dispersible acrylic resin having a refractive index of 1.52 was prepared.

[Production Example 1]
The following easy-adhesion layer A was laminated on one surface of a polyethylene terephthalate film (PET film) having a refractive index of 1.65 and a thickness of 100 μm to obtain a PET film with an easy-adhesion layer. .
The thickness of the easy adhesion layer of the PET film with the easy adhesion layer obtained above was 80 nm, and the refractive index of the easy adhesion layer was 1.64.
<Easily adhesive layer A>
100 parts by mass of polyester resin 1 having a refractive index of 1.64, 5 parts by mass of melamine-based crosslinking agent, and 1 part by mass of colloidal silica are contained.
As the melamine-based crosslinking agent, a methylol-type melamine-based crosslinking agent (“Nicarac MW12LF” manufactured by Sanwa Chemical Co., Ltd.) and as the colloidal silica (“Snowtex OL” manufactured by Nissan Chemical Industries, Ltd.) were used. . In the following Examples and Comparative Examples, the melamine-based crosslinking agent and colloidal silica refer to the above compounds.

[Production Example 2]
A PET film with an easy adhesion layer was obtained in the same manner as in Production Example 1, except that the thickness of the easy adhesion layer A of Production Example 1 was changed to 20 nm.
The thickness of the easy adhesion layer of the PET film with the easy adhesion layer obtained above was 20 nm, and the refractive index of the easy adhesion layer was 1.64.

[Production Example 3]
The following easy-adhesion layer B was laminated on one surface of a polyethylene terephthalate film (PET film) having a refractive index of 1.65 and a thickness of 100 μm to obtain a PET film with an easy-adhesion layer. .
The thickness of the easy adhesion layer of the PET film with the easy adhesion layer obtained above was 20 nm, and the refractive index of the easy adhesion layer was 1.62.
<Easily adhesive layer B>
100 parts by mass of the polyester resin 2 having a refractive index of 1.62 is contained, 5 parts by mass of the melamine-based crosslinking agent, and 1 part by mass of colloidal silica.

[Production Example 4]
The following easy-adhesion layer C was laminated on one surface of a polyethylene terephthalate film (PET film) having a refractive index of 1.65 and a thickness of 100 μm to obtain a PET film with an easy-adhesion layer. .
The thickness of the easy adhesion layer of the PET film with the easy adhesion layer obtained above was 80 nm, and the refractive index of the easy adhesion layer was 1.58.
<Easily adhesive layer C>
100 parts by mass of the polyester resin 3 having a refractive index of 1.58, 5 parts by mass of the melamine-based crosslinking agent, and 1 part by mass of colloidal silica are contained.

[Production Example 5]
A PET film with an easy adhesion layer was obtained in the same manner as in Production Example 4 except that the thickness of the easy adhesion layer C of Production Example 4 was changed to 35 nm.
The thickness of the easy adhesion layer of the PET film with the easy adhesion layer obtained above was 35 nm, and the refractive index of the easy adhesion layer was 1.58.

[Production Example 6]
A PET film with an easy adhesion layer was obtained in the same manner as in Production Example 4 except that the thickness of the easy adhesion layer C of Production Example 4 was changed to 20 nm.
The thickness of the easy adhesion layer of the PET film with the easy adhesion layer obtained above was 20 nm, and the refractive index of the easy adhesion layer was 1.58.

[Production Example 7]
The following easy-adhesion layer D was laminated on one surface of a polyethylene terephthalate film (PET film) having a refractive index of 1.65 and a thickness of 100 μm to obtain a PET film with an easy-adhesion layer. .
The thickness of the easy adhesion layer of the PET film with the easy adhesion layer obtained above was 80 nm, and the refractive index of the easy adhesion layer was 1.52.
<Easily adhesive layer D>
It contains 100 parts by mass of an acrylic resin having a refractive index of 1.52, 5 parts by mass of a melamine-based crosslinking agent, and 1 part by mass of colloidal silica.

[Production Example 8]
A PET film with an easy adhesion layer was obtained in the same manner as in Production Example 7, except that the thickness of the easy adhesion layer D of Production Example 7 was changed to 20 nm.
The thickness of the easy adhesion layer of the PET film with the easy adhesion layer obtained above was 20 nm, and the refractive index of the easy adhesion layer was 1.52.

[Production Example 9]
A PET film with an easy adhesion layer was obtained in the same manner as in Production Example 7, except that the thickness of the easy adhesion layer D of Production Example 7 was changed to 0.5 μm (500 nm).
The thickness of the easy adhesion layer of the PET film with the easy adhesion layer obtained above was 0.5 μm, and the refractive index of the easy adhesion layer was 1.52.

[Production Example 10]
A PET film (refractive index: 1.65, thickness: 100 μm) without an easy adhesion layer was prepared.

[Production Example 11]
On the easy-adhesion layer of the PET film with an easy-adhesion layer obtained in Production Example 1, the following hard coat layer (refractive index 1.54) was laminated so as to have a thickness of 5 μm. Manufactured.
<Hard coat layer>
50 parts by mass of dipentaerythritol hexaacrylate, 20 parts by mass of polyester acrylate, 10 parts by mass of 2-hydroxypropyl acrylate, 20 parts by mass of antimony-doped tin oxide (ATO), photopolymerization initiator (manufactured by Ciba Specialty Chemicals, Inc. 3 parts by mass of Irgacure (registered trademark) 184 ") and 0.5 parts by mass of a silicone leveling agent (" Granol 440 "manufactured by Kyoeisha Chemical Co., Ltd.) in terms of solid content.

[Examples 1-6 and Comparative Examples 1-5]
A thin film layer made of magnesium fluoride (MgF ₂ ) was vacuum-deposited under the following conditions on the easy-adhesion layer of the PET film with an easy-adhesion layer obtained in Production Examples 1 to 9 so as to have a thickness of 100 nm. Laminated to produce an antireflection film. The thin film layer made of magnesium fluoride thus obtained had a refractive index of 1.38 and a thickness of 100 nm.

  Moreover, the antireflection film was manufactured by laminating a thin film layer made of magnesium fluoride in the same manner as described above on one surface of the PET film on which the easy adhesion layer prepared in Production Example 10 was not laminated.

  Furthermore, the thin film layer which consists of magnesium fluoride was laminated | stacked on the hard-coat layer of the PET film with a hard-coat layer obtained by manufacture example 11 similarly to the above, and the antireflection film was manufactured.

  Table 1 shows the relationship between Examples 1 to 6 and Comparative Examples 1 to 5 and Production Examples 1 to 11.

<Conditions for vacuum deposition>
Magnesium fluoride was vapor-deposited on the outermost layer of the long PET film obtained in Production Examples 1 to 11 using a take-up vacuum vapor deposition apparatus equipped with an electron beam evaporation source. After setting the PET film in the vacuum deposition apparatus, the film was evacuated to 5 × 10 ⁻³ Pa or less. The PET film was conveyed at a speed of 1.0 m / min while applying a tension of 130 N / m. The evaporation rate of magnesium fluoride was monitored using a quartz vibrator type film thickness meter. By adjusting the electron beam current of the electron beam evaporation source and controlling the evaporation rate of magnesium fluoride so that the film thickness of the magnesium fluoride vapor-deposited thin film layer obtained on the outermost layer of the PET film is 100 nm, A magnesium thin film layer was obtained.

<Evaluation of antireflection film>
About the antireflection film of the Example obtained by the above and the comparative example, luminous reflectance, reflective color nonuniformity, and adhesiveness were evaluated. These results are shown in Table 1.

  Example 1 of the present invention satisfies condition 1 of the easy-adhesion layer of the present invention, Examples 2 and 3 satisfy conditions 1 and 2 of the easy-adhesion layer of the present invention, and Examples 4 to 6 represent the present invention. Condition 1 of the easy adhesion layer is satisfied. Therefore, Examples 1 to 6 of the present invention have low luminous reflectance, no occurrence of uneven reflection color, and good adhesion.

  On the other hand, in Comparative Examples 1 to 3, the absolute value of the difference in refractive index between the easy adhesion layer and the polyester film (PET film) exceeds 0.05, and the thickness of the easy adhesion layer is 50 nm or more. Neither condition 1 nor condition 2 of the easy-adhesive layer is satisfied. Therefore, Comparative Examples 1 to 3 have high luminous reflectance and inferior antireflection properties. In particular, since the easy adhesion layer of Comparative Example 3 had a large thickness of 500 nm, uneven reflection color occurred.

  Since the comparative example 4 uses the polyester film (PET film) in which the easily bonding layer is not laminated | stacked, adhesiveness was inferior.

  Comparative Example 5 is an example in which a thin film layer was laminated via a hard coat layer, but the luminous reflectance was high, uneven reflection color was generated, and adhesion was inferior.

Claims (5)

A polyester film having a refractive index of 1.6 to 1.7;
An easy adhesion layer directly laminated on the polyester film;
The easy-adhesion layer has a thin film layer directly laminated on the surface opposite to the polyester film side by a vapor deposition method,
The refractive index of the thin film layer is 0.15 or more smaller than the refractive index of the polyester film,
And the said anti-adhesion layer satisfies the following condition 1, condition 2, or (condition 1 and condition 2), the antireflection film.
Condition 1: The absolute value of the difference between the refractive index of the easy adhesion layer and the refractive index of the polyester film is 0.05 or less.
Condition 2: The easy-adhesion layer has a thickness of 5 nm or more and less than 50 nm.   The antireflection film according to claim 1, wherein the thickness of the thin film layer is in the range of 50 to 150 nm.   The antireflection film according to claim 1 or 2, wherein the refractive index of the thin film layer is in the range of 1.2 to 1.5.   The antireflection film according to claim 1, wherein the thin film layer contains a metal fluoride.   The antireflection film according to claim 4, wherein the metal fluoride is magnesium fluoride.